[v6,2/7] slimbus: Add messaging APIs to slimbus framework

Message ID 20171006155136.4682-3-srinivas.kandagatla@linaro.org
State New
Headers show
Series
  • Untitled series #4730
Related show

Commit Message

Srinivas Kandagatla Oct. 6, 2017, 3:51 p.m.
From: Sagar Dharia <sdharia@codeaurora.org>


Slimbus devices use value-element, and information elements to
control device parameters (e.g. value element is used to represent
gain for codec, information element is used to represent interrupt
status for codec when codec interrupt fires).
Messaging APIs are used to set/get these value and information
elements. Slimbus specification uses 8-bit "transaction IDs" for
messages where a read-value is anticipated. Framework uses a table
of pointers to store those TIDs and responds back to the caller in
O(1).
Caller can opt to do synchronous, or asynchronous reads/writes. For
asynchronous operations, the callback will be called from atomic
context.
TX and RX circular rings are used to allow queuing of multiple
transfers per controller. Controller can choose size of these rings
based of controller HW implementation. The buffers are coerently
mapped so that controller can utilize DMA operations for the
transactions without remapping every transaction buffer.
Statically allocated rings help to improve performance by avoiding
overhead of dynamically allocating transactions on need basis.

Signed-off-by: Sagar Dharia <sdharia@codeaurora.org>

Tested-by: Naveen Kaje <nkaje@codeaurora.org>

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>

---
 drivers/slimbus/Makefile         |   2 +-
 drivers/slimbus/slim-core.c      |  15 ++
 drivers/slimbus/slim-messaging.c | 471 +++++++++++++++++++++++++++++++++++++++
 include/linux/slimbus.h          | 161 +++++++++++++
 4 files changed, 648 insertions(+), 1 deletion(-)
 create mode 100644 drivers/slimbus/slim-messaging.c

-- 
2.9.3

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Comments

Jonathan Neuschäfer Oct. 7, 2017, 6:42 a.m. | #1
Hi,

On Fri, Oct 06, 2017 at 05:51:31PM +0200, srinivas.kandagatla@linaro.org wrote:
> From: Sagar Dharia <sdharia@codeaurora.org>

> 

> Slimbus devices use value-element, and information elements to

> control device parameters (e.g. value element is used to represent

> gain for codec, information element is used to represent interrupt

> status for codec when codec interrupt fires).

> Messaging APIs are used to set/get these value and information

> elements. Slimbus specification uses 8-bit "transaction IDs" for

> messages where a read-value is anticipated. Framework uses a table

> of pointers to store those TIDs and responds back to the caller in

> O(1).

> Caller can opt to do synchronous, or asynchronous reads/writes. For

> asynchronous operations, the callback will be called from atomic

> context.

> TX and RX circular rings are used to allow queuing of multiple

> transfers per controller. Controller can choose size of these rings

> based of controller HW implementation. The buffers are coerently


s/based of/based on/
s/coerently/coherently/

> mapped so that controller can utilize DMA operations for the

> transactions without remapping every transaction buffer.

> Statically allocated rings help to improve performance by avoiding

> overhead of dynamically allocating transactions on need basis.

> 

> Signed-off-by: Sagar Dharia <sdharia@codeaurora.org>

> Tested-by: Naveen Kaje <nkaje@codeaurora.org>

> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>

> ---

[...]
> +static u16 slim_slicecodefromsize(u16 req)

> +{

> +	static const u8 codetosize[8] = {1, 2, 3, 4, 6, 8, 12, 16};

> +

> +	if (req >= ARRAY_SIZE(codetosize))

> +		return 0;

> +	else

> +		return codetosize[req];

> +}

> +

> +static u16 slim_slicesize(int code)

> +{

> +	static const u8 sizetocode[16] = {

> +		0, 1, 2, 3, 3, 4, 4, 5, 5, 5, 5, 6, 6, 6, 6, 7

> +	};

> +

> +	clamp(code, 1, (int)ARRAY_SIZE(sizetocode));

> +	return sizetocode[code - 1];

> +}

> +

> +int slim_xfer_msg(struct slim_controller *ctrl,

> +			struct slim_device *sbdev, struct slim_val_inf *msg,

> +			u8 mc)

> +{

> +	DEFINE_SLIM_LDEST_TXN(txn_stack, mc, 6, sbdev->laddr, msg);

> +	struct slim_msg_txn *txn = &txn_stack;

> +	int ret;

> +	u16 sl, cur;

> +

> +	ret = slim_val_inf_sanity(ctrl, msg, mc);

> +	if (ret)

> +		return ret;

> +

> +	sl = slim_slicesize(msg->num_bytes);

> +

> +	dev_dbg(&ctrl->dev, "SB xfer msg:os:%x, len:%d, MC:%x, sl:%x\n",

> +		msg->start_offset, msg->num_bytes, mc, sl);

> +

> +	cur = slim_slicecodefromsize(sl);

> +	txn->ec = ((sl | (1 << 3)) | ((msg->start_offset & 0xFFF) << 4));


Shouldn't this be (cur | (1 << 3)?
(Also, what does cur mean? Cursor? Current?)

> +

> +	switch (mc) {

> +	case SLIM_MSG_MC_REQUEST_CHANGE_VALUE:

> +	case SLIM_MSG_MC_CHANGE_VALUE:

> +	case SLIM_MSG_MC_REQUEST_CLEAR_INFORMATION:

> +	case SLIM_MSG_MC_CLEAR_INFORMATION:

> +		txn->rl += msg->num_bytes;

> +	default:

> +		break;

> +	}

> +

> +	if (slim_tid_txn(txn->mt, txn->mc))

> +		txn->rl++;

> +

> +	return slim_processtxn(ctrl, txn);

> +}

> +EXPORT_SYMBOL_GPL(slim_xfer_msg);

[...]
> +/*

> + * slim_request_val_element: change and request a given value element

> + * @sb: client handle requesting elemental message reads, writes.

> + * @msg: Input structure for start-offset, number of bytes to write.

> + * context: can sleep

> + * Returns:

> + * -EINVAL: Invalid parameters

> + * -ETIMEDOUT: If transmission of this message timed out (e.g. due to bus lines

> + *	not being clocked or driven by controller)

> + * -ENOTCONN: If the transmitted message was not ACKed by destination device.


Does rbuf contain the old value after this function finishes?

> + */

> +int slim_request_change_val_element(struct slim_device *sb,

> +					struct slim_val_inf *msg)

> +{

> +	struct slim_controller *ctrl = sb->ctrl;

> +

> +	if (!ctrl)

> +		return -EINVAL;

> +

> +	return slim_xfer_msg(ctrl, sb, msg, SLIM_MSG_MC_REQUEST_CHANGE_VALUE);

> +}

> +EXPORT_SYMBOL_GPL(slim_request_change_val_element);

[...]
> +/**

> + * struct slim_pending: context of pending transfers

> + * @cb: callback for this transfer

> + * @ctx: contex for the callback function


s/contex/context/

> + * @need_tid: True if this transfer need Transaction ID

> + */

> +struct slim_pending {

> +	void (*cb)(void *ctx, int err);

> +	void *ctx;

> +	bool need_tid;

> +};



Thanks,
Jonathan Neuschäfer
Srinivas Kandagatla Oct. 7, 2017, 10:24 a.m. | #2
Thanks for the comments.

On 07/10/17 07:42, Jonathan Neuschäfer wrote:
> Hi,

> 

> On Fri, Oct 06, 2017 at 05:51:31PM +0200, srinivas.kandagatla@linaro.org wrote:

>> From: Sagar Dharia <sdharia@codeaurora.org>

>>

>> Slimbus devices use value-element, and information elements to

>> control device parameters (e.g. value element is used to represent

>> gain for codec, information element is used to represent interrupt

>> status for codec when codec interrupt fires).

>> Messaging APIs are used to set/get these value and information

>> elements. Slimbus specification uses 8-bit "transaction IDs" for

>> messages where a read-value is anticipated. Framework uses a table

>> of pointers to store those TIDs and responds back to the caller in

>> O(1).

>> Caller can opt to do synchronous, or asynchronous reads/writes. For

>> asynchronous operations, the callback will be called from atomic

>> context.

>> TX and RX circular rings are used to allow queuing of multiple

>> transfers per controller. Controller can choose size of these rings

>> based of controller HW implementation. The buffers are coerently

> 

> s/based of/based on/

> s/coerently/coherently/

Yep.. will fix this in next version.
> 

>> mapped so that controller can utilize DMA operations for the

>> transactions without remapping every transaction buffer.

>> Statically allocated rings help to improve performance by avoiding

>> overhead of dynamically allocating transactions on need basis.

>>

>> Signed-off-by: Sagar Dharia <sdharia@codeaurora.org>

>> Tested-by: Naveen Kaje <nkaje@codeaurora.org>

>> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>

>> ---

> [...]

>> +int slim_xfer_msg(struct slim_controller *ctrl,

>> +			struct slim_device *sbdev, struct slim_val_inf *msg,

>> +			u8 mc)

>> +{

>> +	DEFINE_SLIM_LDEST_TXN(txn_stack, mc, 6, sbdev->laddr, msg);

>> +	struct slim_msg_txn *txn = &txn_stack;

>> +	int ret;

>> +	u16 sl, cur;

>> +

>> +	ret = slim_val_inf_sanity(ctrl, msg, mc);

>> +	if (ret)

>> +		return ret;

>> +

>> +	sl = slim_slicesize(msg->num_bytes);

>> +

>> +	dev_dbg(&ctrl->dev, "SB xfer msg:os:%x, len:%d, MC:%x, sl:%x\n",

>> +		msg->start_offset, msg->num_bytes, mc, sl);

>> +

>> +	cur = slim_slicecodefromsize(sl);

>> +	txn->ec = ((sl | (1 << 3)) | ((msg->start_offset & 0xFFF) << 4));

> 

> Shouldn't this be (cur | (1 << 3)?

cur seems to be redundant TBH, the only difference between cur and sl is 
that the slim_slicesize() can give slice size to program for any lengths 
between 1-16 bytes. However the slim_slicecodefromsize() can only 
handle 1,2,3,4, 6,8,12,16 byte sizes.

So we can delete slim_slicecodefromsize() call and function together.
looks like it was a leftover from downstream.

> (Also, what does cur mean? Cursor? Current?)

No Idea!! :-) it is supposed to return slice size as per number of bytes.

> 

>> +

>> +	switch (mc) {

>> +	case SLIM_MSG_MC_REQUEST_CHANGE_VALUE:

>> +	case SLIM_MSG_MC_CHANGE_VALUE:

>> +	case SLIM_MSG_MC_REQUEST_CLEAR_INFORMATION:

>> +	case SLIM_MSG_MC_CLEAR_INFORMATION:

>> +		txn->rl += msg->num_bytes;

>> +	default:

>> +		break;

>> +	}

>> +

>> +	if (slim_tid_txn(txn->mt, txn->mc))

>> +		txn->rl++;

>> +

>> +	return slim_processtxn(ctrl, txn);

>> +}

>> +EXPORT_SYMBOL_GPL(slim_xfer_msg);

> [...]

>> +/*

>> + * slim_request_val_element: change and request a given value element


name should be fixed here..
>> + * @sb: client handle requesting elemental message reads, writes.

>> + * @msg: Input structure for start-offset, number of bytes to write.

>> + * context: can sleep

>> + * Returns:

>> + * -EINVAL: Invalid parameters

>> + * -ETIMEDOUT: If transmission of this message timed out (e.g. due to bus lines

>> + *	not being clocked or driven by controller)

>> + * -ENOTCONN: If the transmitted message was not ACKed by destination device.

> 

> Does rbuf contain the old value after this function finishes?

> 

Yep, device should send a reply value with the old value with matching tid.

>> + */

>> +int slim_request_change_val_element(struct slim_device *sb,

>> +					struct slim_val_inf *msg)

>> +{

>> +	struct slim_controller *ctrl = sb->ctrl;

>> +

>> +	if (!ctrl)

>> +		return -EINVAL;

>> +

>> +	return slim_xfer_msg(ctrl, sb, msg, SLIM_MSG_MC_REQUEST_CHANGE_VALUE);

>> +}

>> +EXPORT_SYMBOL_GPL(slim_request_change_val_element);

> [...]

>> +/**

>> + * struct slim_pending: context of pending transfers

>> + * @cb: callback for this transfer

>> + * @ctx: contex for the callback function

> 

> s/contex/context/

> 

Will fix all these instances.
>> + * @need_tid: True if this transfer need Transaction ID

>> + */

>> +struct slim_pending {

>> +	void (*cb)(void *ctx, int err);

>> +	void *ctx;

>> +	bool need_tid;

>> +};

> 

> 

> Thanks,

> Jonathan Neuschäfer

> 

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Charles Keepax Oct. 10, 2017, 12:19 p.m. | #3
On Fri, Oct 06, 2017 at 05:51:31PM +0200, srinivas.kandagatla@linaro.org wrote:
> From: Sagar Dharia <sdharia@codeaurora.org>

> 

> Slimbus devices use value-element, and information elements to

> control device parameters (e.g. value element is used to represent

> gain for codec, information element is used to represent interrupt

> status for codec when codec interrupt fires).

> Messaging APIs are used to set/get these value and information

> elements. Slimbus specification uses 8-bit "transaction IDs" for

> messages where a read-value is anticipated. Framework uses a table

> of pointers to store those TIDs and responds back to the caller in

> O(1).

> Caller can opt to do synchronous, or asynchronous reads/writes. For

> asynchronous operations, the callback will be called from atomic

> context.

> TX and RX circular rings are used to allow queuing of multiple

> transfers per controller. Controller can choose size of these rings

> based of controller HW implementation. The buffers are coerently

> mapped so that controller can utilize DMA operations for the

> transactions without remapping every transaction buffer.

> Statically allocated rings help to improve performance by avoiding

> overhead of dynamically allocating transactions on need basis.

> 

> Signed-off-by: Sagar Dharia <sdharia@codeaurora.org>

> Tested-by: Naveen Kaje <nkaje@codeaurora.org>

> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>

> ---

>  drivers/slimbus/Makefile         |   2 +-

>  drivers/slimbus/slim-core.c      |  15 ++

>  drivers/slimbus/slim-messaging.c | 471 +++++++++++++++++++++++++++++++++++++++

>  include/linux/slimbus.h          | 161 +++++++++++++

>  4 files changed, 648 insertions(+), 1 deletion(-)

>  create mode 100644 drivers/slimbus/slim-messaging.c

> 

> +/**

> + * slim_processtxn: Process a slimbus-messaging transaction

> + * @ctrl: Controller handle

> + * @txn: Transaction to be sent over SLIMbus

> + * Called by controller to transmit messaging transactions not dealing with

> + * Interface/Value elements. (e.g. transmittting a message to assign logical

> + * address to a slave device

> + * Returns:

> + * -ETIMEDOUT: If transmission of this message timed out (e.g. due to bus lines

> + *	not being clocked or driven by controller)

> + * -ENOTCONN: If the transmitted message was not ACKed by destination device.

> + */

> +int slim_processtxn(struct slim_controller *ctrl,

> +				struct slim_msg_txn *txn)


Can all go on one line.

> +{

> +	int ret, i = 0;

> +	unsigned long flags;

> +	u8 *buf;

> +	bool async = false;

> +	struct slim_cb_data cbd;

> +	DECLARE_COMPLETION_ONSTACK(done);

> +	bool need_tid = slim_tid_txn(txn->mt, txn->mc);

> +

> +	if (!txn->msg->comp_cb) {

> +		txn->msg->comp_cb = slim_sync_default_cb;

> +		cbd.comp = &done;

> +		txn->msg->ctx = &cbd;

> +	} else {

> +		async = true;

> +	}

> +

> +	buf = slim_get_tx(ctrl, txn, need_tid);

> +	if (!buf)

> +		return -ENOMEM;

> +

> +	if (need_tid) {

> +		spin_lock_irqsave(&ctrl->txn_lock, flags);

> +		for (i = 0; i < ctrl->last_tid; i++) {

> +			if (ctrl->tid_tbl[i] == NULL)

> +				break;

> +		}

> +		if (i >= ctrl->last_tid) {

> +			if (ctrl->last_tid == (SLIM_MAX_TIDS - 1)) {

> +				spin_unlock_irqrestore(&ctrl->txn_lock, flags);

> +				slim_return_tx(ctrl, -ENOMEM);

> +				return -ENOMEM;

> +			}

> +			ctrl->last_tid++;

> +		}

> +		ctrl->tid_tbl[i] = txn->msg;

> +		txn->tid = i;

> +		spin_unlock_irqrestore(&ctrl->txn_lock, flags);

> +	}

> +

> +	ret = ctrl->xfer_msg(ctrl, txn, buf);

> +

> +	if (!ret && !async) { /* sync transaction */

> +		/* Fine-tune calculation after bandwidth management */

> +		unsigned long ms = txn->rl + 100;

> +

> +		ret = wait_for_completion_timeout(&done,

> +						  msecs_to_jiffies(ms));

> +		if (!ret)

> +			slim_return_tx(ctrl, -ETIMEDOUT);

> +

> +		ret = cbd.ret;

> +	}

> +

> +	if (ret && need_tid) {

> +		spin_lock_irqsave(&ctrl->txn_lock, flags);

> +		/* Invalidate the transaction */

> +		ctrl->tid_tbl[txn->tid] = NULL;

> +		spin_unlock_irqrestore(&ctrl->txn_lock, flags);

> +	}

> +	if (ret)

> +		dev_err(&ctrl->dev, "Tx:MT:0x%x, MC:0x%x, LA:0x%x failed:%d\n",

> +			txn->mt, txn->mc, txn->la, ret);

> +	if (!async) {

> +		txn->msg->comp_cb = NULL;

> +		txn->msg->ctx = NULL;

> +	}


What is the intent of this if statement here? We set async
locally so this code only runs if we executed the else on the if
statement at the top. If its just clearing anything the user
might have put in these fields why not do it up there.

> +	return ret;

> +}

> +EXPORT_SYMBOL_GPL(slim_processtxn);

> +

> +int slim_xfer_msg(struct slim_controller *ctrl,

> +			struct slim_device *sbdev, struct slim_val_inf *msg,

> +			u8 mc)

> +{

> +	DEFINE_SLIM_LDEST_TXN(txn_stack, mc, 6, sbdev->laddr, msg);

> +	struct slim_msg_txn *txn = &txn_stack;

> +	int ret;

> +	u16 sl, cur;

> +

> +	ret = slim_val_inf_sanity(ctrl, msg, mc);

> +	if (ret)

> +		return ret;

> +

> +	sl = slim_slicesize(msg->num_bytes);

> +

> +	dev_dbg(&ctrl->dev, "SB xfer msg:os:%x, len:%d, MC:%x, sl:%x\n",

> +		msg->start_offset, msg->num_bytes, mc, sl);

> +

> +	cur = slim_slicecodefromsize(sl);


cur should probably be removed until it is needed.

> +	txn->ec = ((sl | (1 << 3)) | ((msg->start_offset & 0xFFF) << 4));

> +

> +	switch (mc) {

> +	case SLIM_MSG_MC_REQUEST_CHANGE_VALUE:

> +	case SLIM_MSG_MC_CHANGE_VALUE:

> +	case SLIM_MSG_MC_REQUEST_CLEAR_INFORMATION:

> +	case SLIM_MSG_MC_CLEAR_INFORMATION:

> +		txn->rl += msg->num_bytes;

> +	default:

> +		break;

> +	}

> +

> +	if (slim_tid_txn(txn->mt, txn->mc))

> +		txn->rl++;

> +

> +	return slim_processtxn(ctrl, txn);

> +}

> +EXPORT_SYMBOL_GPL(slim_xfer_msg);

> +

> +/* Message APIs Unicast message APIs used by slimbus slave drivers */

> +

> +/*

> + * slim_request_val_element: request value element

> + * @sb: client handle requesting elemental message reads, writes.

> + * @msg: Input structure for start-offset, number of bytes to read.

> + * context: can sleep

> + * Returns:

> + * -EINVAL: Invalid parameters

> + * -ETIMEDOUT: If transmission of this message timed out (e.g. due to bus lines

> + *	not being clocked or driven by controller)

> + * -ENOTCONN: If the transmitted message was not ACKed by destination device.

> + */

> +int slim_request_val_element(struct slim_device *sb,

> +				struct slim_val_inf *msg)

> +{

> +	struct slim_controller *ctrl = sb->ctrl;

> +

> +	if (!ctrl)

> +		return -EINVAL;


You could put this check into slim_xfer_msg and save duplicating
it. Would also then cover cases that call that function directly,
also would let you make these functions either inlines or macros.

> +

> +	return slim_xfer_msg(ctrl, sb, msg, SLIM_MSG_MC_REQUEST_VALUE);

> +}

> +EXPORT_SYMBOL_GPL(slim_request_val_element);

> +

> +/* Functions to get/return TX, RX buffers for messaging. */

> +

> +/**

> + * slim_get_rx: To get RX buffers for messaging.

> + * @ctrl: Controller handle

> + * These functions are called by controller to process the RX buffers.

> + * RX buffer is requested by controller when data is received from HW, but is

> + * not processed (e.g. 'report-present message was sent by HW in ISR and SW

> + * needs more time to process the buffer to assign Logical Address)

> + * RX buffer is returned back to the pool when associated RX action

> + * is taken (e.g. Received message is decoded and client's

> + * response buffer is filled in.)

> + */

> +void *slim_get_rx(struct slim_controller *ctrl)

> +{

> +	unsigned long flags;

> +	int idx;

> +

> +	spin_lock_irqsave(&ctrl->rx.lock, flags);

> +	if ((ctrl->rx.tail + 1) % ctrl->rx.n == ctrl->rx.head) {

> +		spin_unlock_irqrestore(&ctrl->rx.lock, flags);

> +		dev_err(&ctrl->dev, "RX QUEUE full!");

> +		return NULL;

> +	}

> +	idx = ctrl->rx.tail;

> +	ctrl->rx.tail = (ctrl->rx.tail + 1) % ctrl->rx.n;

> +	spin_unlock_irqrestore(&ctrl->rx.lock, flags);

> +

> +	return ctrl->rx.base + (idx * ctrl->rx.sl_sz);

> +}

> +EXPORT_SYMBOL_GPL(slim_get_rx);

> +

> +int slim_return_rx(struct slim_controller *ctrl, void *buf)

> +{

> +	unsigned long flags;

> +

> +	spin_lock_irqsave(&ctrl->rx.lock, flags);

> +	if (ctrl->rx.tail == ctrl->rx.head) {

> +		spin_unlock_irqrestore(&ctrl->rx.lock, flags);

> +		return -ENODATA;

> +	}

> +	memcpy(buf, ctrl->rx.base + (ctrl->rx.head * ctrl->rx.sl_sz),

> +				ctrl->rx.sl_sz);

> +	ctrl->rx.head = (ctrl->rx.head + 1) % ctrl->rx.n;

> +	spin_unlock_irqrestore(&ctrl->rx.lock, flags);

> +

> +	return 0;

> +}

> +EXPORT_SYMBOL_GPL(slim_return_rx);


I find the combination of get/return a bit odd, would get/put
maybe more idiomatic? Also the return could use some kernel doc.

> +

> +void slim_return_tx(struct slim_controller *ctrl, int err)

> +{

> +	unsigned long flags;

> +	int idx;

> +	struct slim_pending cur;

> +

> +	spin_lock_irqsave(&ctrl->tx.lock, flags);

> +	idx = ctrl->tx.head;

> +	ctrl->tx.head = (ctrl->tx.head + 1) % ctrl->tx.n;

> +	cur = ctrl->pending_wr[idx];

> +	spin_unlock_irqrestore(&ctrl->tx.lock, flags);

> +

> +	if (!cur.cb)

> +		dev_err(&ctrl->dev, "NULL Transaction or completion");

> +	else

> +		cur.cb(cur.ctx, err);

> +

> +	up(&ctrl->tx_sem);

> +}

> +EXPORT_SYMBOL_GPL(slim_return_tx);

> +

> +/**

> + * slim_get_tx: To get TX buffers for messaging.

> + * @ctrl: Controller handle

> + * These functions are called by controller to process the TX buffers.

> + * TX buffer is requested by controller when it's filled-in and sent to the

> + * HW. When HW has finished processing this buffer, controller should return it

> + * back to the pool.

> + */

> +void *slim_get_tx(struct slim_controller *ctrl, struct slim_msg_txn *txn,

> +		bool need_tid)

> +{

> +	unsigned long flags;

> +	int ret, idx;

> +

> +	ret = down_interruptible(&ctrl->tx_sem);

> +	if (ret < 0) {

> +		dev_err(&ctrl->dev, "TX semaphore down returned:%d", ret);

> +		return NULL;

> +	}

> +	spin_lock_irqsave(&ctrl->tx.lock, flags);

> +

> +	if (((ctrl->tx.head + 1) % ctrl->tx.n) == ctrl->tx.tail) {

> +		spin_unlock_irqrestore(&ctrl->tx.lock, flags);

> +		dev_err(&ctrl->dev, "controller TX buf unavailable");

> +		up(&ctrl->tx_sem);

> +		return NULL;

> +	}

> +	idx = ctrl->tx.tail;

> +	ctrl->tx.tail = (ctrl->tx.tail + 1) % ctrl->tx.n;

> +	ctrl->pending_wr[idx].cb = txn->msg->comp_cb;

> +	ctrl->pending_wr[idx].ctx = txn->msg->ctx;

> +	ctrl->pending_wr[idx].need_tid = need_tid;

> +	spin_unlock_irqrestore(&ctrl->tx.lock, flags);

> +

> +	return ctrl->tx.base + (idx * ctrl->tx.sl_sz);

> +}

> +EXPORT_SYMBOL_GPL(slim_get_tx);


The rx calls seem ok that is basically the controller's job to
call those, but with these two calls it seems sometimes the
framework calls them sometimes the controller driver has to. Is
there anyway we can simplify that a bit? Or at least include some
documentation as to when the controller should call them.

> diff --git a/include/linux/slimbus.h b/include/linux/slimbus.h

> index b5064b6..080d86a 100644

> --- a/include/linux/slimbus.h

> +++ b/include/linux/slimbus.h

> @@ -15,6 +15,7 @@

>  #include <linux/module.h>

>  #include <linux/device.h>

>  #include <linux/mutex.h>

> +#include <linux/semaphore.h>

>  #include <linux/mod_devicetable.h>

>  

>  /**

> @@ -34,6 +35,9 @@ extern struct bus_type slimbus_type;

>  #define SLIM_FRM_SLOTS_PER_SUPERFRAME	16

>  #define SLIM_GDE_SLOTS_PER_SUPERFRAME	2

>  

> +/* MAX in-flight transactions neededing transaction ID (8-bit, per spec) */


s/neededing/needing/

> +

> +/* Frequently used message transaction structures */

> +#define DEFINE_SLIM_LDEST_TXN(name, mc, rl, la, msg) \

> +	struct slim_msg_txn name = { rl, 0, mc, SLIM_MSG_DEST_LOGICALADDR, 0,\

> +					0, la, msg, }

> +

> +#define DEFINE_SLIM_BCAST_TXN(name, mc, rl, la, msg) \

> +	struct slim_msg_txn name = { rl, 0, mc, SLIM_MSG_DEST_BROADCAST, 0,\

> +					0, la, msg, }


If the LA isn't used in broadcast messages wouldn't it be simpler
to set it to a fixed value in this macro?

> +

> +#define DEFINE_SLIM_EDEST_TXN(name, mc, rl, la, msg) \

> +	struct slim_msg_txn name = { rl, 0, mc, SLIM_MSG_DEST_ENUMADDR, 0,\

> +					0, la, msg, }

> +


Also one final overall comment this commit contains a lot of two
and three letter abreviations that are not always clear. I would
probably suggest expanding a few of the less standard ones out to
make the code a little easier to follow.

Thanks,
Charles
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Vinod Koul Oct. 11, 2017, 4:38 a.m. | #4
On Fri, Oct 06, 2017 at 05:51:31PM +0200, srinivas.kandagatla@linaro.org wrote:

>  	mutex_init(&ctrl->m_ctrl);

> +	spin_lock_init(&ctrl->tx.lock);

> +	spin_lock_init(&ctrl->rx.lock);


locks galore :) My assumption is that you want to optimize these? But given
that audio user is going to be serialized do we practically need two locks?

> +

> +	ctrl->pending_wr = kcalloc((ctrl->tx.n - 1),

> +				   sizeof(struct slim_pending),

> +				   GFP_KERNEL);

> +	if (!ctrl->pending_wr) {

> +		ret = -ENOMEM;

> +		goto wr_alloc_failed;

> +	}

> +

> +	sema_init(&ctrl->tx_sem, (ctrl->tx.n - 1));


i though v5 comment from Arnd was not to use semaphores..

> +/* Copyright (c) 2011-2016, The Linux Foundation. All rights reserved.


2017?

> +int slim_processtxn(struct slim_controller *ctrl,


slim_process_txn seems more readable to me

> +				struct slim_msg_txn *txn)

> +{

> +	int ret, i = 0;

> +	unsigned long flags;

> +	u8 *buf;

> +	bool async = false;

> +	struct slim_cb_data cbd;

> +	DECLARE_COMPLETION_ONSTACK(done);

> +	bool need_tid = slim_tid_txn(txn->mt, txn->mc);

> +

> +	if (!txn->msg->comp_cb) {

> +		txn->msg->comp_cb = slim_sync_default_cb;

> +		cbd.comp = &done;

> +		txn->msg->ctx = &cbd;

> +	} else {

> +		async = true;

> +	}

> +

> +	buf = slim_get_tx(ctrl, txn, need_tid);

> +	if (!buf)

> +		return -ENOMEM;

> +

> +	if (need_tid) {

> +		spin_lock_irqsave(&ctrl->txn_lock, flags);

> +		for (i = 0; i < ctrl->last_tid; i++) {

> +			if (ctrl->tid_tbl[i] == NULL)

> +				break;

> +		}

> +		if (i >= ctrl->last_tid) {

> +			if (ctrl->last_tid == (SLIM_MAX_TIDS - 1)) {

> +				spin_unlock_irqrestore(&ctrl->txn_lock, flags);

> +				slim_return_tx(ctrl, -ENOMEM);

> +				return -ENOMEM;

> +			}

> +			ctrl->last_tid++;

> +		}

> +		ctrl->tid_tbl[i] = txn->msg;

> +		txn->tid = i;

> +		spin_unlock_irqrestore(&ctrl->txn_lock, flags);

> +	}

> +

> +	ret = ctrl->xfer_msg(ctrl, txn, buf);

> +

> +	if (!ret && !async) { /* sync transaction */

> +		/* Fine-tune calculation after bandwidth management */

> +		unsigned long ms = txn->rl + 100;

> +

> +		ret = wait_for_completion_timeout(&done,

> +						  msecs_to_jiffies(ms));

> +		if (!ret)

> +			slim_return_tx(ctrl, -ETIMEDOUT);

> +

> +		ret = cbd.ret;

> +	}

> +

> +	if (ret && need_tid) {

> +		spin_lock_irqsave(&ctrl->txn_lock, flags);

> +		/* Invalidate the transaction */

> +		ctrl->tid_tbl[txn->tid] = NULL;

> +		spin_unlock_irqrestore(&ctrl->txn_lock, flags);

> +	}

> +	if (ret)

> +		dev_err(&ctrl->dev, "Tx:MT:0x%x, MC:0x%x, LA:0x%x failed:%d\n",

> +			txn->mt, txn->mc, txn->la, ret);

> +	if (!async) {

> +		txn->msg->comp_cb = NULL;

> +		txn->msg->ctx = NULL;

> +	}

> +	return ret;

> +}

> +EXPORT_SYMBOL_GPL(slim_processtxn);


that is interesting, I was expecting this to be internal API. So users are
expected to use this which is not very convenient IMO. Can we hide the gory
details and give users simple tx/rx or read/write APIs. FWIW most of the
usage would be thru regmap where people would call regmap_read/write()

> +

> +static int slim_val_inf_sanity(struct slim_controller *ctrl,

> +			       struct slim_val_inf *msg, u8 mc)

> +{

> +	if (!msg || msg->num_bytes > 16 ||

> +	    (msg->start_offset + msg->num_bytes) > 0xC00)

> +		goto reterr;


line break here

> +	switch (mc) {

> +	case SLIM_MSG_MC_REQUEST_VALUE:

> +	case SLIM_MSG_MC_REQUEST_INFORMATION:


what does MC refer to?

> +		if (msg->rbuf != NULL)

> +			return 0;

> +		break;


after each break too

> +static u16 slim_slicecodefromsize(u16 req)


hmmm Linux code doesnt prefernamesnames like this :)

> +EXPORT_SYMBOL_GPL(slim_request_inf_element);

> +

> +


unnecessary double space

> +struct slim_val_inf {

> +	u16			start_offset;

> +	u8			num_bytes;

> +	u8			*rbuf;

> +	const u8		*wbuf;


can we do read and write, if not it can be a buf which maybe rbuf or wbug
based on type

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Arnd Bergmann Oct. 11, 2017, 7:53 a.m. | #5
On Wed, Oct 11, 2017 at 6:38 AM, Vinod Koul <vinod.koul@intel.com> wrote:
> On Fri, Oct 06, 2017 at 05:51:31PM +0200, srinivas.kandagatla@linaro.org wrote:

>> +     ctrl->pending_wr = kcalloc((ctrl->tx.n - 1),

>> +                                sizeof(struct slim_pending),

>> +                                GFP_KERNEL);

>> +     if (!ctrl->pending_wr) {

>> +             ret = -ENOMEM;

>> +             goto wr_alloc_failed;

>> +     }

>> +

>> +     sema_init(&ctrl->tx_sem, (ctrl->tx.n - 1));

>

> i though v5 comment from Arnd was not to use semaphores..


Right, these need to go away. Thanks for spotting it!

     Arnd
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Vinod Koul Oct. 11, 2017, 10:24 a.m. | #6
On Wed, Oct 11, 2017 at 10:42:28AM +0100, Srinivas Kandagatla wrote:
> On 11/10/17 05:38, Vinod Koul wrote:

> >On Fri, Oct 06, 2017 at 05:51:31PM +0200, srinivas.kandagatla@linaro.org wrote:

> >

> >>  	mutex_init(&ctrl->m_ctrl);

> >>+	spin_lock_init(&ctrl->tx.lock);

> >>+	spin_lock_init(&ctrl->rx.lock);

> >

> >locks galore :) My assumption is that you want to optimize these? But given

> >that audio user is going to be serialized do we practically need two locks?

> >

> If we remove the locking, It will be issue if we have multiple devices in a

> component, which is common atleast with the codec which am looking at.


can you explian what you mean by a "device" here?

> >>+	switch (mc) {

> >>+	case SLIM_MSG_MC_REQUEST_VALUE:

> >>+	case SLIM_MSG_MC_REQUEST_INFORMATION:

> >

> >what does MC refer to?

> 

> Message Code.


isnt SLIM_MSG enough :D I think we cna get rid of MC here..

> >>+struct slim_val_inf {

> >>+	u16			start_offset;

> >>+	u8			num_bytes;

> >>+	u8			*rbuf;

> >>+	const u8		*wbuf;

> >

> >can we do read and write, if not it can be a buf which maybe rbuf or wbug

> >based on type

> With REQUEST_CHANGE_VALUE single command we can read old value at the same

> time we can write new value.


so that is a read modify write, correct? Is that implemented in HW, if so we
need to provide only write value

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Bjorn Andersson Oct. 18, 2017, 6:15 a.m. | #7
On Fri 06 Oct 08:51 PDT 2017, srinivas.kandagatla@linaro.org wrote:

> From: Sagar Dharia <sdharia@codeaurora.org>

> 

> Slimbus devices use value-element, and information elements to

> control device parameters (e.g. value element is used to represent

> gain for codec, information element is used to represent interrupt

> status for codec when codec interrupt fires).

> Messaging APIs are used to set/get these value and information

> elements. Slimbus specification uses 8-bit "transaction IDs" for

> messages where a read-value is anticipated. Framework uses a table

> of pointers to store those TIDs and responds back to the caller in

> O(1).


I think we can implement this "optimization" with less complex code,
regardless I don't think we need to mention this in the commit
message...

[..]
> diff --git a/drivers/slimbus/slim-messaging.c b/drivers/slimbus/slim-messaging.c

[..]
> +/**

> + * slim_msg_response: Deliver Message response received from a device to the

> + *	framework.

> + * @ctrl: Controller handle

> + * @reply: Reply received from the device

> + * @len: Length of the reply

> + * @tid: Transaction ID received with which framework can associate reply.

> + * Called by controller to inform framework about the response received.

> + * This helps in making the API asynchronous, and controller-driver doesn't need

> + * to manage 1 more table other than the one managed by framework mapping TID

> + * with buffers

> + */

> +void slim_msg_response(struct slim_controller *ctrl, u8 *reply, u8 tid, u8 len)


Even if tid and len comes from the spec I recommend you making them int
and size_t.

> +{

> +	struct slim_val_inf *msg;

> +	unsigned long flags;

> +

> +	spin_lock_irqsave(&ctrl->txn_lock, flags);

> +	msg = ctrl->tid_tbl[tid];

> +	if (msg == NULL || msg->rbuf == NULL) {


if (!msg || !msg->rbuf)


When is it valid to add a transaction to tid_tbl with msg->rbuf = NULL?
Should we reject it earlier?

> +		spin_unlock_irqrestore(&ctrl->txn_lock, flags);

> +		dev_err(&ctrl->dev, "Got response to invalid TID:%d, len:%d\n",

> +				tid, len);

> +		return;

> +	}

> +	ctrl->tid_tbl[tid] = NULL;

> +	spin_unlock_irqrestore(&ctrl->txn_lock, flags);

> +

> +	memcpy(msg->rbuf, reply, len);

> +	if (msg->comp_cb)

> +		msg->comp_cb(msg->ctx, 0);

> +}

> +EXPORT_SYMBOL_GPL(slim_msg_response);

[..]
> +int slim_processtxn(struct slim_controller *ctrl,

> +				struct slim_msg_txn *txn)

> +{

> +	int ret, i = 0;

> +	unsigned long flags;

> +	u8 *buf;

> +	bool async = false;

> +	struct slim_cb_data cbd;

> +	DECLARE_COMPLETION_ONSTACK(done);

> +	bool need_tid = slim_tid_txn(txn->mt, txn->mc);

> +

> +	if (!txn->msg->comp_cb) {

> +		txn->msg->comp_cb = slim_sync_default_cb;

> +		cbd.comp = &done;

> +		txn->msg->ctx = &cbd;

> +	} else {

> +		async = true;

> +	}

> +

> +	buf = slim_get_tx(ctrl, txn, need_tid);

> +	if (!buf)

> +		return -ENOMEM;

> +

> +	if (need_tid) {

> +		spin_lock_irqsave(&ctrl->txn_lock, flags);

> +		for (i = 0; i < ctrl->last_tid; i++) {

> +			if (ctrl->tid_tbl[i] == NULL)

> +				break;

> +		}

> +		if (i >= ctrl->last_tid) {

> +			if (ctrl->last_tid == (SLIM_MAX_TIDS - 1)) {

> +				spin_unlock_irqrestore(&ctrl->txn_lock, flags);

> +				slim_return_tx(ctrl, -ENOMEM);

> +				return -ENOMEM;

> +			}

> +			ctrl->last_tid++;

> +		}

> +		ctrl->tid_tbl[i] = txn->msg;

> +		txn->tid = i;

> +		spin_unlock_irqrestore(&ctrl->txn_lock, flags);

> +	}

> +

> +	ret = ctrl->xfer_msg(ctrl, txn, buf);

> +

> +	if (!ret && !async) { /* sync transaction */

> +		/* Fine-tune calculation after bandwidth management */

> +		unsigned long ms = txn->rl + 100;

> +

> +		ret = wait_for_completion_timeout(&done,

> +						  msecs_to_jiffies(ms));

> +		if (!ret)

> +			slim_return_tx(ctrl, -ETIMEDOUT);

> +

> +		ret = cbd.ret;

> +	}

> +

> +	if (ret && need_tid) {

> +		spin_lock_irqsave(&ctrl->txn_lock, flags);

> +		/* Invalidate the transaction */

> +		ctrl->tid_tbl[txn->tid] = NULL;

> +		spin_unlock_irqrestore(&ctrl->txn_lock, flags);

> +	}

> +	if (ret)

> +		dev_err(&ctrl->dev, "Tx:MT:0x%x, MC:0x%x, LA:0x%x failed:%d\n",

> +			txn->mt, txn->mc, txn->la, ret);


if (ret) {
	if (need_tid)
		drop();
	
	dev_err();
}

Would probably make this a little bit cleaner...

> +	if (!async) {

> +		txn->msg->comp_cb = NULL;

> +		txn->msg->ctx = NULL;


I believe txn->msg is always required, so you don't need to do this
contidionally.

> +	}

> +	return ret;

> +}

> +EXPORT_SYMBOL_GPL(slim_processtxn);

[..]
> +int slim_request_val_element(struct slim_device *sb,

> +				struct slim_val_inf *msg)

> +{

> +	struct slim_controller *ctrl = sb->ctrl;

> +

> +	if (!ctrl)

> +		return -EINVAL;


From patch 1 I believe it's invalid for sb->ctrl to be NULL, so there
shouldn't be a need to check this.

> +

> +	return slim_xfer_msg(ctrl, sb, msg, SLIM_MSG_MC_REQUEST_VALUE);

> +}

> +EXPORT_SYMBOL_GPL(slim_request_val_element);

[..]
> +int slim_return_rx(struct slim_controller *ctrl, void *buf)

> +{

> +	unsigned long flags;

> +

> +	spin_lock_irqsave(&ctrl->rx.lock, flags);

> +	if (ctrl->rx.tail == ctrl->rx.head) {

> +		spin_unlock_irqrestore(&ctrl->rx.lock, flags);

> +		return -ENODATA;

> +	}

> +	memcpy(buf, ctrl->rx.base + (ctrl->rx.head * ctrl->rx.sl_sz),

> +				ctrl->rx.sl_sz);

> +	ctrl->rx.head = (ctrl->rx.head + 1) % ctrl->rx.n;

> +	spin_unlock_irqrestore(&ctrl->rx.lock, flags);

> +

> +	return 0;

> +}

> +EXPORT_SYMBOL_GPL(slim_return_rx);

> +


Please provide kerneldoc for exported symbols.

> +void slim_return_tx(struct slim_controller *ctrl, int err)

> +{

> +	unsigned long flags;

> +	int idx;

> +	struct slim_pending cur;

> +

> +	spin_lock_irqsave(&ctrl->tx.lock, flags);

> +	idx = ctrl->tx.head;

> +	ctrl->tx.head = (ctrl->tx.head + 1) % ctrl->tx.n;

> +	cur = ctrl->pending_wr[idx];


Why is this doing struct copy?

> +	spin_unlock_irqrestore(&ctrl->tx.lock, flags);

> +

> +	if (!cur.cb)

> +		dev_err(&ctrl->dev, "NULL Transaction or completion");

> +	else

> +		cur.cb(cur.ctx, err);

> +

> +	up(&ctrl->tx_sem);

> +}

> +EXPORT_SYMBOL_GPL(slim_return_tx);

[..]
>  /**

> + * struct slim_val_inf: Slimbus value or information element

> + * @start_offset: Specifies starting offset in information/value element map

> + * @num_bytes: upto 16. This ensures that the message will fit the slicesize

> + *		per slimbus spec

> + * @comp_cb: Callback if this read/write is asynchronous

> + * @ctx: Argument for comp_cb

> + */

> +struct slim_val_inf {

> +	u16			start_offset;

> +	u8			num_bytes;

> +	u8			*rbuf;


This is not mentioned in the kerneldoc. Use void * for data buffers.

> +	const u8		*wbuf;


Can a message ever be read and write? Otherwise it should be sufficient
to only have one data pointer.

> +	void			(*comp_cb)(void *ctx, int err);

> +	void			*ctx;

> +};

> +

[..]
> +/**

> + * struct slim_ctrl_buf: circular buffer used by contoller for TX, RX

> + * @base: virtual base address for this buffer

> + * @phy: physical address for this buffer (this is useful if controller can

> + *	  DMA the buffers for TX and RX to/from controller hardware

> + * @lock: lock protecting head and tail

> + * @head: index where buffer is returned back

> + * @tail: index from where buffer is consumed

> + * @sl_sz: byte-size of each slot in this buffer

> + * @n:	  number of elements in this circular ring, note that this needs to be

> + *	1 more than actual buffers to allow for one open slot

> + */


Is this ringbuffer mechanism defined in the slimbus specification? Looks
like something specific to the Qualcomm controller, rather than
something that should be enforced in the framework.

> +struct slim_ctrl_buf {

> +	void		*base;

> +	phys_addr_t	phy;

> +	spinlock_t	lock;

> +	int		head;

> +	int		tail;

> +	int		sl_sz;

> +	int		n;

> +};

[..]
> +/**

>   * struct slim_controller: Controls every instance of SLIMbus

>   *				(similar to 'master' on SPI)

>   *	'Manager device' is responsible for  device management, bandwidth

> @@ -139,6 +246,16 @@ struct slim_addrt {

>   * @addrt: Logical address table

>   * @num_dev: Number of active slimbus slaves on this bus

>   * @wq: Workqueue per controller used to notify devices when they report present

> + * @tid_tbl: Table of transactions having transaction ID

> + * @txn_lock: Lock to protect table of transactions

> + * @rx: RX buffers used by controller to receive messages. Ctrl may receive more

> + *	than 1 message (e.g. multiple report-present messages or messages from

> + *	multiple slaves).

> + * @tx: TX buffers used by controller to transmit messages. Ctrl may have

> + *	ability to send/queue multiple messages to HW at once.

> + * @pending_wr: Pending write transactions to be acknowledged by controller


This is out list of pending write requests, yet it's implemented as an
array used in a complex ring buffer fashion. Wouldn't it be easier to
just have this as a linked list of slim_pending struct?

> + * @tx_sem: Semaphore for available TX buffers for this controller

> + * @last_tid: Last used entry for TID transactions

>   * @xfer_msg: Transfer a message on this controller (this can be a broadcast

>   *	control/status message like data channel setup, or a unicast message

>   *	like value element read/write.

> @@ -161,6 +278,15 @@ struct slim_controller {

>  	struct slim_addrt	*addrt;

>  	u8			num_dev;

>  	struct workqueue_struct *wq;

> +	struct slim_val_inf	*tid_tbl[SLIM_MAX_TIDS];

> +	u8			last_tid;


I suggest that you replace these two with an idr, rather than having a
fixed size array and then last_tid as an optimization to limit how far
you linear search for an empty space.

> +	spinlock_t		txn_lock;

> +	struct slim_ctrl_buf	tx;

> +	struct slim_ctrl_buf	rx;

> +	struct slim_pending	*pending_wr;

> +	struct semaphore	tx_sem;


Please don't use semaphores. If you keep pending_wr as a list you can
use list_empty() instead...

> +	int			(*xfer_msg)(struct slim_controller *ctrl,

> +					    struct slim_msg_txn *tx, void *buf);


I believe buf has fixed size, so please document this.

>  	int			(*set_laddr)(struct slim_controller *ctrl,

>  					     struct slim_eaddr *ea, u8 laddr);

>  	int			(*get_laddr)(struct slim_controller *ctrl,

> @@ -295,5 +421,40 @@ static inline void slim_set_devicedata(struct slim_device *dev, void *data)

>  {

>  	dev_set_drvdata(&dev->dev, data);

>  }


Regards,
Bjorn
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Patch

diff --git a/drivers/slimbus/Makefile b/drivers/slimbus/Makefile
index f580704..bd1d35e 100644
--- a/drivers/slimbus/Makefile
+++ b/drivers/slimbus/Makefile
@@ -2,4 +2,4 @@ 
 # Makefile for kernel slimbus framework.
 #
 obj-$(CONFIG_SLIMBUS)			+= slimbus.o
-slimbus-y				:= slim-core.o
+slimbus-y				:= slim-core.o slim-messaging.o
diff --git a/drivers/slimbus/slim-core.c b/drivers/slimbus/slim-core.c
index de3ef79..5b1da28 100644
--- a/drivers/slimbus/slim-core.c
+++ b/drivers/slimbus/slim-core.c
@@ -362,6 +362,19 @@  int slim_register_controller(struct slim_controller *ctrl)
 		ctrl->max_cg = SLIM_MAX_CLK_GEAR;
 
 	mutex_init(&ctrl->m_ctrl);
+	spin_lock_init(&ctrl->tx.lock);
+	spin_lock_init(&ctrl->rx.lock);
+
+	ctrl->pending_wr = kcalloc((ctrl->tx.n - 1),
+				   sizeof(struct slim_pending),
+				   GFP_KERNEL);
+	if (!ctrl->pending_wr) {
+		ret = -ENOMEM;
+		goto wr_alloc_failed;
+	}
+
+	sema_init(&ctrl->tx_sem, (ctrl->tx.n - 1));
+
 	ret = device_register(&ctrl->dev);
 	if (ret)
 		goto dev_reg_failed;
@@ -380,6 +393,8 @@  int slim_register_controller(struct slim_controller *ctrl)
 err_workq_failed:
 	device_unregister(&ctrl->dev);
 dev_reg_failed:
+	kfree(ctrl->pending_wr);
+wr_alloc_failed:
 	mutex_lock(&slim_lock);
 	idr_remove(&ctrl_idr, ctrl->nr);
 	mutex_unlock(&slim_lock);
diff --git a/drivers/slimbus/slim-messaging.c b/drivers/slimbus/slim-messaging.c
new file mode 100644
index 0000000..adcba67
--- /dev/null
+++ b/drivers/slimbus/slim-messaging.c
@@ -0,0 +1,471 @@ 
+/* Copyright (c) 2011-2016, The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+#include <linux/slab.h>
+#include <linux/slimbus.h>
+
+/**
+ * slim_msg_response: Deliver Message response received from a device to the
+ *	framework.
+ * @ctrl: Controller handle
+ * @reply: Reply received from the device
+ * @len: Length of the reply
+ * @tid: Transaction ID received with which framework can associate reply.
+ * Called by controller to inform framework about the response received.
+ * This helps in making the API asynchronous, and controller-driver doesn't need
+ * to manage 1 more table other than the one managed by framework mapping TID
+ * with buffers
+ */
+void slim_msg_response(struct slim_controller *ctrl, u8 *reply, u8 tid, u8 len)
+{
+	struct slim_val_inf *msg;
+	unsigned long flags;
+
+	spin_lock_irqsave(&ctrl->txn_lock, flags);
+	msg = ctrl->tid_tbl[tid];
+	if (msg == NULL || msg->rbuf == NULL) {
+		spin_unlock_irqrestore(&ctrl->txn_lock, flags);
+		dev_err(&ctrl->dev, "Got response to invalid TID:%d, len:%d\n",
+				tid, len);
+		return;
+	}
+	ctrl->tid_tbl[tid] = NULL;
+	spin_unlock_irqrestore(&ctrl->txn_lock, flags);
+
+	memcpy(msg->rbuf, reply, len);
+	if (msg->comp_cb)
+		msg->comp_cb(msg->ctx, 0);
+}
+EXPORT_SYMBOL_GPL(slim_msg_response);
+
+struct slim_cb_data {
+	struct completion *comp;
+	int ret;
+};
+
+static void slim_sync_default_cb(void *ctx, int err)
+{
+	struct slim_cb_data *cbd = ctx;
+
+	cbd->ret = err;
+	complete(cbd->comp);
+}
+
+/**
+ * slim_processtxn: Process a slimbus-messaging transaction
+ * @ctrl: Controller handle
+ * @txn: Transaction to be sent over SLIMbus
+ * Called by controller to transmit messaging transactions not dealing with
+ * Interface/Value elements. (e.g. transmittting a message to assign logical
+ * address to a slave device
+ * Returns:
+ * -ETIMEDOUT: If transmission of this message timed out (e.g. due to bus lines
+ *	not being clocked or driven by controller)
+ * -ENOTCONN: If the transmitted message was not ACKed by destination device.
+ */
+int slim_processtxn(struct slim_controller *ctrl,
+				struct slim_msg_txn *txn)
+{
+	int ret, i = 0;
+	unsigned long flags;
+	u8 *buf;
+	bool async = false;
+	struct slim_cb_data cbd;
+	DECLARE_COMPLETION_ONSTACK(done);
+	bool need_tid = slim_tid_txn(txn->mt, txn->mc);
+
+	if (!txn->msg->comp_cb) {
+		txn->msg->comp_cb = slim_sync_default_cb;
+		cbd.comp = &done;
+		txn->msg->ctx = &cbd;
+	} else {
+		async = true;
+	}
+
+	buf = slim_get_tx(ctrl, txn, need_tid);
+	if (!buf)
+		return -ENOMEM;
+
+	if (need_tid) {
+		spin_lock_irqsave(&ctrl->txn_lock, flags);
+		for (i = 0; i < ctrl->last_tid; i++) {
+			if (ctrl->tid_tbl[i] == NULL)
+				break;
+		}
+		if (i >= ctrl->last_tid) {
+			if (ctrl->last_tid == (SLIM_MAX_TIDS - 1)) {
+				spin_unlock_irqrestore(&ctrl->txn_lock, flags);
+				slim_return_tx(ctrl, -ENOMEM);
+				return -ENOMEM;
+			}
+			ctrl->last_tid++;
+		}
+		ctrl->tid_tbl[i] = txn->msg;
+		txn->tid = i;
+		spin_unlock_irqrestore(&ctrl->txn_lock, flags);
+	}
+
+	ret = ctrl->xfer_msg(ctrl, txn, buf);
+
+	if (!ret && !async) { /* sync transaction */
+		/* Fine-tune calculation after bandwidth management */
+		unsigned long ms = txn->rl + 100;
+
+		ret = wait_for_completion_timeout(&done,
+						  msecs_to_jiffies(ms));
+		if (!ret)
+			slim_return_tx(ctrl, -ETIMEDOUT);
+
+		ret = cbd.ret;
+	}
+
+	if (ret && need_tid) {
+		spin_lock_irqsave(&ctrl->txn_lock, flags);
+		/* Invalidate the transaction */
+		ctrl->tid_tbl[txn->tid] = NULL;
+		spin_unlock_irqrestore(&ctrl->txn_lock, flags);
+	}
+	if (ret)
+		dev_err(&ctrl->dev, "Tx:MT:0x%x, MC:0x%x, LA:0x%x failed:%d\n",
+			txn->mt, txn->mc, txn->la, ret);
+	if (!async) {
+		txn->msg->comp_cb = NULL;
+		txn->msg->ctx = NULL;
+	}
+	return ret;
+}
+EXPORT_SYMBOL_GPL(slim_processtxn);
+
+static int slim_val_inf_sanity(struct slim_controller *ctrl,
+			       struct slim_val_inf *msg, u8 mc)
+{
+	if (!msg || msg->num_bytes > 16 ||
+	    (msg->start_offset + msg->num_bytes) > 0xC00)
+		goto reterr;
+	switch (mc) {
+	case SLIM_MSG_MC_REQUEST_VALUE:
+	case SLIM_MSG_MC_REQUEST_INFORMATION:
+		if (msg->rbuf != NULL)
+			return 0;
+		break;
+	case SLIM_MSG_MC_CHANGE_VALUE:
+	case SLIM_MSG_MC_CLEAR_INFORMATION:
+		if (msg->wbuf != NULL)
+			return 0;
+		break;
+	case SLIM_MSG_MC_REQUEST_CHANGE_VALUE:
+	case SLIM_MSG_MC_REQUEST_CLEAR_INFORMATION:
+		if (msg->rbuf != NULL && msg->wbuf != NULL)
+			return 0;
+		break;
+	default:
+		break;
+	}
+reterr:
+	dev_err(&ctrl->dev, "Sanity check failed:msg:offset:0x%x, mc:%d\n",
+		msg->start_offset, mc);
+	return -EINVAL;
+}
+
+static u16 slim_slicecodefromsize(u16 req)
+{
+	static const u8 codetosize[8] = {1, 2, 3, 4, 6, 8, 12, 16};
+
+	if (req >= ARRAY_SIZE(codetosize))
+		return 0;
+	else
+		return codetosize[req];
+}
+
+static u16 slim_slicesize(int code)
+{
+	static const u8 sizetocode[16] = {
+		0, 1, 2, 3, 3, 4, 4, 5, 5, 5, 5, 6, 6, 6, 6, 7
+	};
+
+	clamp(code, 1, (int)ARRAY_SIZE(sizetocode));
+	return sizetocode[code - 1];
+}
+
+int slim_xfer_msg(struct slim_controller *ctrl,
+			struct slim_device *sbdev, struct slim_val_inf *msg,
+			u8 mc)
+{
+	DEFINE_SLIM_LDEST_TXN(txn_stack, mc, 6, sbdev->laddr, msg);
+	struct slim_msg_txn *txn = &txn_stack;
+	int ret;
+	u16 sl, cur;
+
+	ret = slim_val_inf_sanity(ctrl, msg, mc);
+	if (ret)
+		return ret;
+
+	sl = slim_slicesize(msg->num_bytes);
+
+	dev_dbg(&ctrl->dev, "SB xfer msg:os:%x, len:%d, MC:%x, sl:%x\n",
+		msg->start_offset, msg->num_bytes, mc, sl);
+
+	cur = slim_slicecodefromsize(sl);
+	txn->ec = ((sl | (1 << 3)) | ((msg->start_offset & 0xFFF) << 4));
+
+	switch (mc) {
+	case SLIM_MSG_MC_REQUEST_CHANGE_VALUE:
+	case SLIM_MSG_MC_CHANGE_VALUE:
+	case SLIM_MSG_MC_REQUEST_CLEAR_INFORMATION:
+	case SLIM_MSG_MC_CLEAR_INFORMATION:
+		txn->rl += msg->num_bytes;
+	default:
+		break;
+	}
+
+	if (slim_tid_txn(txn->mt, txn->mc))
+		txn->rl++;
+
+	return slim_processtxn(ctrl, txn);
+}
+EXPORT_SYMBOL_GPL(slim_xfer_msg);
+
+/* Message APIs Unicast message APIs used by slimbus slave drivers */
+
+/*
+ * slim_request_val_element: request value element
+ * @sb: client handle requesting elemental message reads, writes.
+ * @msg: Input structure for start-offset, number of bytes to read.
+ * context: can sleep
+ * Returns:
+ * -EINVAL: Invalid parameters
+ * -ETIMEDOUT: If transmission of this message timed out (e.g. due to bus lines
+ *	not being clocked or driven by controller)
+ * -ENOTCONN: If the transmitted message was not ACKed by destination device.
+ */
+int slim_request_val_element(struct slim_device *sb,
+				struct slim_val_inf *msg)
+{
+	struct slim_controller *ctrl = sb->ctrl;
+
+	if (!ctrl)
+		return -EINVAL;
+
+	return slim_xfer_msg(ctrl, sb, msg, SLIM_MSG_MC_REQUEST_VALUE);
+}
+EXPORT_SYMBOL_GPL(slim_request_val_element);
+
+/**
+ * slim_request_inf_element: Request a info element
+ * @sb: client handle requesting elemental message reads.
+ * @msg: Input structure for start-offset, number of bytes to read
+ *	wbuf will contain information element(s) bit masks to be cleared.
+ *	rbuf will return what the information element value was
+ */
+int slim_request_inf_element(struct slim_device *sb,
+				struct slim_val_inf *msg)
+{
+	struct slim_controller *ctrl = sb->ctrl;
+
+	if (!ctrl)
+		return -EINVAL;
+
+	return slim_xfer_msg(ctrl, sb, msg, SLIM_MSG_MC_REQUEST_INFORMATION);
+}
+EXPORT_SYMBOL_GPL(slim_request_inf_element);
+
+
+/*
+ * slim_change_val_element: change a given value element
+ * @sb: client handle requesting elemental message reads, writes.
+ * @msg: Input structure for start-offset, number of bytes to write.
+ * context: can sleep
+ * Returns:
+ * -EINVAL: Invalid parameters
+ * -ETIMEDOUT: If transmission of this message timed out (e.g. due to bus lines
+ *	not being clocked or driven by controller)
+ * -ENOTCONN: If the transmitted message was not ACKed by destination device.
+ */
+int slim_change_val_element(struct slim_device *sb, struct slim_val_inf *msg)
+{
+	struct slim_controller *ctrl = sb->ctrl;
+
+	if (!ctrl)
+		return -EINVAL;
+
+	return slim_xfer_msg(ctrl, sb, msg, SLIM_MSG_MC_CHANGE_VALUE);
+}
+EXPORT_SYMBOL_GPL(slim_change_val_element);
+
+/**
+ * slim_clear_inf_element: Clear info element
+ * @sb: client handle requesting elemental message reads, writes.
+ * @msg: Input structure for start-offset, number of bytes to read
+ *	wbuf will contain information element(s) bit masks to be cleared.
+ *	rbuf will return what the information element value was
+ */
+int slim_clear_inf_element(struct slim_device *sb, struct slim_val_inf *msg)
+{
+	struct slim_controller *ctrl = sb->ctrl;
+
+	if (!ctrl)
+		return -EINVAL;
+
+	return slim_xfer_msg(ctrl, sb, msg, SLIM_MSG_MC_CLEAR_INFORMATION);
+}
+EXPORT_SYMBOL_GPL(slim_clear_inf_element);
+
+/*
+ * slim_request_val_element: change and request a given value element
+ * @sb: client handle requesting elemental message reads, writes.
+ * @msg: Input structure for start-offset, number of bytes to write.
+ * context: can sleep
+ * Returns:
+ * -EINVAL: Invalid parameters
+ * -ETIMEDOUT: If transmission of this message timed out (e.g. due to bus lines
+ *	not being clocked or driven by controller)
+ * -ENOTCONN: If the transmitted message was not ACKed by destination device.
+ */
+int slim_request_change_val_element(struct slim_device *sb,
+					struct slim_val_inf *msg)
+{
+	struct slim_controller *ctrl = sb->ctrl;
+
+	if (!ctrl)
+		return -EINVAL;
+
+	return slim_xfer_msg(ctrl, sb, msg, SLIM_MSG_MC_REQUEST_CHANGE_VALUE);
+}
+EXPORT_SYMBOL_GPL(slim_request_change_val_element);
+
+/**
+ * slim_request_clear_inf_element: Clear and request info element
+ * @sb: client handle requesting elemental message reads, writes.
+ * @msg: Input structure for start-offset, number of bytes to read
+ *	wbuf will contain information element(s) bit masks to be cleared.
+ *	rbuf will return what the information element value was
+ */
+int slim_request_clear_inf_element(struct slim_device *sb,
+					struct slim_val_inf *msg)
+{
+	struct slim_controller *ctrl = sb->ctrl;
+
+	if (!ctrl)
+		return -EINVAL;
+
+	return slim_xfer_msg(ctrl, sb, msg,
+					SLIM_MSG_MC_REQUEST_CLEAR_INFORMATION);
+}
+EXPORT_SYMBOL_GPL(slim_request_clear_inf_element);
+
+/* Functions to get/return TX, RX buffers for messaging. */
+
+/**
+ * slim_get_rx: To get RX buffers for messaging.
+ * @ctrl: Controller handle
+ * These functions are called by controller to process the RX buffers.
+ * RX buffer is requested by controller when data is received from HW, but is
+ * not processed (e.g. 'report-present message was sent by HW in ISR and SW
+ * needs more time to process the buffer to assign Logical Address)
+ * RX buffer is returned back to the pool when associated RX action
+ * is taken (e.g. Received message is decoded and client's
+ * response buffer is filled in.)
+ */
+void *slim_get_rx(struct slim_controller *ctrl)
+{
+	unsigned long flags;
+	int idx;
+
+	spin_lock_irqsave(&ctrl->rx.lock, flags);
+	if ((ctrl->rx.tail + 1) % ctrl->rx.n == ctrl->rx.head) {
+		spin_unlock_irqrestore(&ctrl->rx.lock, flags);
+		dev_err(&ctrl->dev, "RX QUEUE full!");
+		return NULL;
+	}
+	idx = ctrl->rx.tail;
+	ctrl->rx.tail = (ctrl->rx.tail + 1) % ctrl->rx.n;
+	spin_unlock_irqrestore(&ctrl->rx.lock, flags);
+
+	return ctrl->rx.base + (idx * ctrl->rx.sl_sz);
+}
+EXPORT_SYMBOL_GPL(slim_get_rx);
+
+int slim_return_rx(struct slim_controller *ctrl, void *buf)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&ctrl->rx.lock, flags);
+	if (ctrl->rx.tail == ctrl->rx.head) {
+		spin_unlock_irqrestore(&ctrl->rx.lock, flags);
+		return -ENODATA;
+	}
+	memcpy(buf, ctrl->rx.base + (ctrl->rx.head * ctrl->rx.sl_sz),
+				ctrl->rx.sl_sz);
+	ctrl->rx.head = (ctrl->rx.head + 1) % ctrl->rx.n;
+	spin_unlock_irqrestore(&ctrl->rx.lock, flags);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(slim_return_rx);
+
+void slim_return_tx(struct slim_controller *ctrl, int err)
+{
+	unsigned long flags;
+	int idx;
+	struct slim_pending cur;
+
+	spin_lock_irqsave(&ctrl->tx.lock, flags);
+	idx = ctrl->tx.head;
+	ctrl->tx.head = (ctrl->tx.head + 1) % ctrl->tx.n;
+	cur = ctrl->pending_wr[idx];
+	spin_unlock_irqrestore(&ctrl->tx.lock, flags);
+
+	if (!cur.cb)
+		dev_err(&ctrl->dev, "NULL Transaction or completion");
+	else
+		cur.cb(cur.ctx, err);
+
+	up(&ctrl->tx_sem);
+}
+EXPORT_SYMBOL_GPL(slim_return_tx);
+
+/**
+ * slim_get_tx: To get TX buffers for messaging.
+ * @ctrl: Controller handle
+ * These functions are called by controller to process the TX buffers.
+ * TX buffer is requested by controller when it's filled-in and sent to the
+ * HW. When HW has finished processing this buffer, controller should return it
+ * back to the pool.
+ */
+void *slim_get_tx(struct slim_controller *ctrl, struct slim_msg_txn *txn,
+		bool need_tid)
+{
+	unsigned long flags;
+	int ret, idx;
+
+	ret = down_interruptible(&ctrl->tx_sem);
+	if (ret < 0) {
+		dev_err(&ctrl->dev, "TX semaphore down returned:%d", ret);
+		return NULL;
+	}
+	spin_lock_irqsave(&ctrl->tx.lock, flags);
+
+	if (((ctrl->tx.head + 1) % ctrl->tx.n) == ctrl->tx.tail) {
+		spin_unlock_irqrestore(&ctrl->tx.lock, flags);
+		dev_err(&ctrl->dev, "controller TX buf unavailable");
+		up(&ctrl->tx_sem);
+		return NULL;
+	}
+	idx = ctrl->tx.tail;
+	ctrl->tx.tail = (ctrl->tx.tail + 1) % ctrl->tx.n;
+	ctrl->pending_wr[idx].cb = txn->msg->comp_cb;
+	ctrl->pending_wr[idx].ctx = txn->msg->ctx;
+	ctrl->pending_wr[idx].need_tid = need_tid;
+	spin_unlock_irqrestore(&ctrl->tx.lock, flags);
+
+	return ctrl->tx.base + (idx * ctrl->tx.sl_sz);
+}
+EXPORT_SYMBOL_GPL(slim_get_tx);
diff --git a/include/linux/slimbus.h b/include/linux/slimbus.h
index b5064b6..080d86a 100644
--- a/include/linux/slimbus.h
+++ b/include/linux/slimbus.h
@@ -15,6 +15,7 @@ 
 #include <linux/module.h>
 #include <linux/device.h>
 #include <linux/mutex.h>
+#include <linux/semaphore.h>
 #include <linux/mod_devicetable.h>
 
 /**
@@ -34,6 +35,9 @@  extern struct bus_type slimbus_type;
 #define SLIM_FRM_SLOTS_PER_SUPERFRAME	16
 #define SLIM_GDE_SLOTS_PER_SUPERFRAME	2
 
+/* MAX in-flight transactions neededing transaction ID (8-bit, per spec) */
+#define SLIM_MAX_TIDS			256
+
 struct slim_controller;
 struct slim_device;
 
@@ -100,12 +104,115 @@  struct slim_addrt {
 #define SLIM_MSG_MC_ASSIGN_LOGICAL_ADDRESS       0x2
 #define SLIM_MSG_MC_REPORT_ABSENT                0xF
 
+/* Information Element management messages */
+#define SLIM_MSG_MC_REQUEST_INFORMATION          0x20
+#define SLIM_MSG_MC_REQUEST_CLEAR_INFORMATION    0x21
+#define SLIM_MSG_MC_REPLY_INFORMATION            0x24
+#define SLIM_MSG_MC_CLEAR_INFORMATION            0x28
+#define SLIM_MSG_MC_REPORT_INFORMATION           0x29
+
+/* Value Element management messages */
+#define SLIM_MSG_MC_REQUEST_VALUE                0x60
+#define SLIM_MSG_MC_REQUEST_CHANGE_VALUE         0x61
+#define SLIM_MSG_MC_REPLY_VALUE                  0x64
+#define SLIM_MSG_MC_CHANGE_VALUE                 0x68
+
 /* Destination type Values */
 #define SLIM_MSG_DEST_LOGICALADDR	0
 #define SLIM_MSG_DEST_ENUMADDR		1
 #define	SLIM_MSG_DEST_BROADCAST		3
 
 /**
+ * struct slim_val_inf: Slimbus value or information element
+ * @start_offset: Specifies starting offset in information/value element map
+ * @num_bytes: upto 16. This ensures that the message will fit the slicesize
+ *		per slimbus spec
+ * @comp_cb: Callback if this read/write is asynchronous
+ * @ctx: Argument for comp_cb
+ */
+struct slim_val_inf {
+	u16			start_offset;
+	u8			num_bytes;
+	u8			*rbuf;
+	const u8		*wbuf;
+	void			(*comp_cb)(void *ctx, int err);
+	void			*ctx;
+};
+
+/**
+ * struct slim_msg_txn: Message to be sent by the controller.
+ * This structure has packet header, payload and buffer to be filled (if any)
+ * @rl: Header field. remaining length.
+ * @mt: Header field. Message type.
+ * @mc: Header field. LSB is message code for type mt.
+ * @dt: Header field. Destination type.
+ * @ec: Element code. Used for elemental access APIs.
+ * @len: Length of payload. (excludes ec)
+ * @tid: Transaction ID. Used for messages expecting response.
+ *	(relevant for message-codes involving read operation)
+ * @la: Logical address of the device this message is going to.
+ *	(Not used when destination type is broadcast.)
+ * @msg: Elemental access message to be read/written
+ */
+struct slim_msg_txn {
+	u8			rl;
+	u8			mt;
+	u8			mc;
+	u8			dt;
+	u16			ec;
+	u8			tid;
+	u8			la;
+	struct slim_val_inf	*msg;
+};
+
+/* Frequently used message transaction structures */
+#define DEFINE_SLIM_LDEST_TXN(name, mc, rl, la, msg) \
+	struct slim_msg_txn name = { rl, 0, mc, SLIM_MSG_DEST_LOGICALADDR, 0,\
+					0, la, msg, }
+
+#define DEFINE_SLIM_BCAST_TXN(name, mc, rl, la, msg) \
+	struct slim_msg_txn name = { rl, 0, mc, SLIM_MSG_DEST_BROADCAST, 0,\
+					0, la, msg, }
+
+#define DEFINE_SLIM_EDEST_TXN(name, mc, rl, la, msg) \
+	struct slim_msg_txn name = { rl, 0, mc, SLIM_MSG_DEST_ENUMADDR, 0,\
+					0, la, msg, }
+
+/**
+ * struct slim_ctrl_buf: circular buffer used by contoller for TX, RX
+ * @base: virtual base address for this buffer
+ * @phy: physical address for this buffer (this is useful if controller can
+ *	  DMA the buffers for TX and RX to/from controller hardware
+ * @lock: lock protecting head and tail
+ * @head: index where buffer is returned back
+ * @tail: index from where buffer is consumed
+ * @sl_sz: byte-size of each slot in this buffer
+ * @n:	  number of elements in this circular ring, note that this needs to be
+ *	1 more than actual buffers to allow for one open slot
+ */
+struct slim_ctrl_buf {
+	void		*base;
+	phys_addr_t	phy;
+	spinlock_t	lock;
+	int		head;
+	int		tail;
+	int		sl_sz;
+	int		n;
+};
+
+/**
+ * struct slim_pending: context of pending transfers
+ * @cb: callback for this transfer
+ * @ctx: contex for the callback function
+ * @need_tid: True if this transfer need Transaction ID
+ */
+struct slim_pending {
+	void (*cb)(void *ctx, int err);
+	void *ctx;
+	bool need_tid;
+};
+
+/**
  * struct slim_controller: Controls every instance of SLIMbus
  *				(similar to 'master' on SPI)
  *	'Manager device' is responsible for  device management, bandwidth
@@ -139,6 +246,16 @@  struct slim_addrt {
  * @addrt: Logical address table
  * @num_dev: Number of active slimbus slaves on this bus
  * @wq: Workqueue per controller used to notify devices when they report present
+ * @tid_tbl: Table of transactions having transaction ID
+ * @txn_lock: Lock to protect table of transactions
+ * @rx: RX buffers used by controller to receive messages. Ctrl may receive more
+ *	than 1 message (e.g. multiple report-present messages or messages from
+ *	multiple slaves).
+ * @tx: TX buffers used by controller to transmit messages. Ctrl may have
+ *	ability to send/queue multiple messages to HW at once.
+ * @pending_wr: Pending write transactions to be acknowledged by controller
+ * @tx_sem: Semaphore for available TX buffers for this controller
+ * @last_tid: Last used entry for TID transactions
  * @xfer_msg: Transfer a message on this controller (this can be a broadcast
  *	control/status message like data channel setup, or a unicast message
  *	like value element read/write.
@@ -161,6 +278,15 @@  struct slim_controller {
 	struct slim_addrt	*addrt;
 	u8			num_dev;
 	struct workqueue_struct *wq;
+	struct slim_val_inf	*tid_tbl[SLIM_MAX_TIDS];
+	u8			last_tid;
+	spinlock_t		txn_lock;
+	struct slim_ctrl_buf	tx;
+	struct slim_ctrl_buf	rx;
+	struct slim_pending	*pending_wr;
+	struct semaphore	tx_sem;
+	int			(*xfer_msg)(struct slim_controller *ctrl,
+					    struct slim_msg_txn *tx, void *buf);
 	int			(*set_laddr)(struct slim_controller *ctrl,
 					     struct slim_eaddr *ea, u8 laddr);
 	int			(*get_laddr)(struct slim_controller *ctrl,
@@ -295,5 +421,40 @@  static inline void slim_set_devicedata(struct slim_device *dev, void *data)
 {
 	dev_set_drvdata(&dev->dev, data);
 }
+int slim_request_val_element(struct slim_device *sb,
+					struct slim_val_inf *msg);
+int slim_change_val_element(struct slim_device *sb,
+					struct slim_val_inf *msg);
+int slim_request_change_val_element(struct slim_device *sb,
+					struct slim_val_inf *msg);
+
+
+
+int slim_request_inf_element(struct slim_device *sb,
+					struct slim_val_inf *msg);
+int slim_clear_inf_element(struct slim_device *sb,
+					struct slim_val_inf *msg);
+int slim_request_clear_inf_element(struct slim_device *sb,
+					struct slim_val_inf *msg);
+void slim_msg_response(struct slim_controller *ctrl, u8 *reply, u8 tid,
+				u8 len);
+
+int slim_processtxn(struct slim_controller *ctrl, struct slim_msg_txn *txn);
+
+void *slim_get_rx(struct slim_controller *ctrl);
+int slim_return_rx(struct slim_controller *ctrl, void *buf);
+void *slim_get_tx(struct slim_controller *ctrl, struct slim_msg_txn *txn,
+		  bool need_tid);
+void slim_return_tx(struct slim_controller *ctrl, int err);
+
+static inline bool slim_tid_txn(u8 mt, u8 mc)
+{
+	return (mt == SLIM_MSG_MT_CORE &&
+		(mc == SLIM_MSG_MC_REQUEST_INFORMATION ||
+		 mc == SLIM_MSG_MC_REQUEST_CLEAR_INFORMATION ||
+		 mc == SLIM_MSG_MC_REQUEST_VALUE ||
+		 mc == SLIM_MSG_MC_REQUEST_CLEAR_INFORMATION));
+}
+/* end of message apis */
 
 #endif /* _LINUX_SLIMBUS_H */