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[V2,0/2] Implement Shutdown callback for i2c

Message ID 20200820103522.26242-1-rojay@codeaurora.org
Headers show
Series Implement Shutdown callback for i2c | expand

Message

Roja Rani Yarubandi Aug. 20, 2020, 10:35 a.m. UTC 
Store DMA mapping data in geni_i2c_dev struct.
Implement Shutdown callback for geni i2c driver.

Changes in V2:
 - Changed commit text.
 - As per Stephen's comments added separate function for stop transfer.

Roja Rani Yarubandi (2):
  i2c: i2c-qcom-geni: Store DMA mapping data in geni_i2c_dev struct
  i2c: i2c-qcom-geni: Add shutdown callback for i2c

 drivers/i2c/busses/i2c-qcom-geni.c | 50 ++++++++++++++++++++++++++++++
 include/linux/qcom-geni-se.h       |  5 +++
 2 files changed, 55 insertions(+)

Comments

Stephen Boyd Aug. 21, 2020, 12:22 a.m. UTC | #1 
Quoting Roja Rani Yarubandi (2020-08-20 03:35:22)
> If the hardware is still accessing memory after SMMU translation
> is disabled (as part of smmu shutdown callback), then the
> IOVAs (I/O virtual address) which it was using will go on the bus
> as the physical addresses which will result in unknown crashes
> like NoC/interconnect errors.
> 
> So, implement shutdown callback to i2c driver to unmap DMA mappings
> during system "reboot" or "shutdown".
> 
> Signed-off-by: Roja Rani Yarubandi <rojay@codeaurora.org>
> ---

I'd still put a Fixes tag because it's fixing the driver when someone
runs shutdown.

> Changes in V2:
>  - As per Stephen's comments added seperate function for stop transfer,
>    fixed minor nitpicks.
> 
>  drivers/i2c/busses/i2c-qcom-geni.c | 43 ++++++++++++++++++++++++++++++
>  include/linux/qcom-geni-se.h       |  5 ++++
>  2 files changed, 48 insertions(+)
> 
> diff --git a/drivers/i2c/busses/i2c-qcom-geni.c b/drivers/i2c/busses/i2c-qcom-geni.c
> index 1fda5c7c2cfc..d07f2f33bb75 100644
> --- a/drivers/i2c/busses/i2c-qcom-geni.c
> +++ b/drivers/i2c/busses/i2c-qcom-geni.c
> @@ -486,6 +486,28 @@ static int geni_i2c_xfer(struct i2c_adapter *adap,
>         return ret;
>  }
>  
> +static void geni_i2c_stop_xfer(struct geni_i2c_dev *gi2c)
> +{
> +       u32 val;
> +       struct geni_se *se = &gi2c->se;
> +
> +       val = readl_relaxed(gi2c->se.base + SE_DMA_DEBUG_REG0);
> +       if (val & DMA_TX_ACTIVE) {
> +               geni_i2c_abort_xfer(gi2c);
> +               gi2c->cur_wr = 0;
> +               if (gi2c->err)
> +                       geni_i2c_tx_fsm_rst(gi2c);
> +               geni_se_tx_dma_unprep(se, gi2c->tx_dma, gi2c->xfer_len);
> +       }
> +       if (val & DMA_RX_ACTIVE) {
> +               geni_i2c_abort_xfer(gi2c);
> +               gi2c->cur_rd = 0;
> +               if (gi2c->err)
> +                       geni_i2c_rx_fsm_rst(gi2c);
> +               geni_se_rx_dma_unprep(se, gi2c->rx_dma, gi2c->xfer_len);
> +       }
> +}
> +
>  static u32 geni_i2c_func(struct i2c_adapter *adap)
>  {
>         return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK);
> @@ -617,6 +639,26 @@ static int geni_i2c_remove(struct platform_device *pdev)
>         return 0;
>  }
>  
> +static void geni_i2c_shutdown(struct platform_device *pdev)
> +{
> +       int ret;
> +       u32 dma;
> +       struct geni_i2c_dev *gi2c = platform_get_drvdata(pdev);
> +       struct geni_se *se = &gi2c->se;
> +
> +       ret = pm_runtime_get_sync(gi2c->se.dev);
> +       if (ret < 0) {
> +               dev_err(gi2c->se.dev, "Failed to resume device: %d\n", ret);
> +               return;
> +       }
> +
> +       dma = readl_relaxed(se->base + SE_GENI_DMA_MODE_EN);
> +       if (dma)
> +               geni_i2c_stop_xfer(gi2c);

Any reason the if (dma) check isn't inside geni_i2c_stop_xfer()?
Checking for dma and then bailing out early should work and keep the
logic in one function. Then the pm_runtime_sync() call could go in there
too and if (!dma) goto out. This assumes that we're going to call
geni_i2c_stop_xfer() from somewhere else, like if a transfer times out
or something?

> +
> +       pm_runtime_put_sync_suspend(gi2c->se.dev);
> +}
> +
>  static int __maybe_unused geni_i2c_runtime_suspend(struct device *dev)
>  {
>         int ret;
Roja Rani Yarubandi Aug. 28, 2020, 11:46 a.m. UTC | #2 
On 2020-08-21 05:52, Stephen Boyd wrote:
> Quoting Roja Rani Yarubandi (2020-08-20 03:35:22)
>> If the hardware is still accessing memory after SMMU translation
>> is disabled (as part of smmu shutdown callback), then the
>> IOVAs (I/O virtual address) which it was using will go on the bus
>> as the physical addresses which will result in unknown crashes
>> like NoC/interconnect errors.
>> 
>> So, implement shutdown callback to i2c driver to unmap DMA mappings
>> during system "reboot" or "shutdown".
>> 
>> Signed-off-by: Roja Rani Yarubandi <rojay@codeaurora.org>
>> ---
> 
> I'd still put a Fixes tag because it's fixing the driver when someone
> runs shutdown.
> 

Okay, will add fixes tag.

>> Changes in V2:
>>  - As per Stephen's comments added seperate function for stop 
>> transfer,
>>    fixed minor nitpicks.
>> 
>>  drivers/i2c/busses/i2c-qcom-geni.c | 43 
>> ++++++++++++++++++++++++++++++
>>  include/linux/qcom-geni-se.h       |  5 ++++
>>  2 files changed, 48 insertions(+)
>> 
>> diff --git a/drivers/i2c/busses/i2c-qcom-geni.c 
>> b/drivers/i2c/busses/i2c-qcom-geni.c
>> index 1fda5c7c2cfc..d07f2f33bb75 100644
>> --- a/drivers/i2c/busses/i2c-qcom-geni.c
>> +++ b/drivers/i2c/busses/i2c-qcom-geni.c
>> @@ -486,6 +486,28 @@ static int geni_i2c_xfer(struct i2c_adapter 
>> *adap,
>>         return ret;
>>  }
>> 
>> +static void geni_i2c_stop_xfer(struct geni_i2c_dev *gi2c)
>> +{
>> +       u32 val;
>> +       struct geni_se *se = &gi2c->se;
>> +
>> +       val = readl_relaxed(gi2c->se.base + SE_DMA_DEBUG_REG0);
>> +       if (val & DMA_TX_ACTIVE) {
>> +               geni_i2c_abort_xfer(gi2c);
>> +               gi2c->cur_wr = 0;
>> +               if (gi2c->err)
>> +                       geni_i2c_tx_fsm_rst(gi2c);
>> +               geni_se_tx_dma_unprep(se, gi2c->tx_dma, 
>> gi2c->xfer_len);
>> +       }
>> +       if (val & DMA_RX_ACTIVE) {
>> +               geni_i2c_abort_xfer(gi2c);
>> +               gi2c->cur_rd = 0;
>> +               if (gi2c->err)
>> +                       geni_i2c_rx_fsm_rst(gi2c);
>> +               geni_se_rx_dma_unprep(se, gi2c->rx_dma, 
>> gi2c->xfer_len);
>> +       }
>> +}
>> +
>>  static u32 geni_i2c_func(struct i2c_adapter *adap)
>>  {
>>         return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & 
>> ~I2C_FUNC_SMBUS_QUICK);
>> @@ -617,6 +639,26 @@ static int geni_i2c_remove(struct platform_device 
>> *pdev)
>>         return 0;
>>  }
>> 
>> +static void geni_i2c_shutdown(struct platform_device *pdev)
>> +{
>> +       int ret;
>> +       u32 dma;
>> +       struct geni_i2c_dev *gi2c = platform_get_drvdata(pdev);
>> +       struct geni_se *se = &gi2c->se;
>> +
>> +       ret = pm_runtime_get_sync(gi2c->se.dev);
>> +       if (ret < 0) {
>> +               dev_err(gi2c->se.dev, "Failed to resume device: %d\n", 
>> ret);
>> +               return;
>> +       }
>> +
>> +       dma = readl_relaxed(se->base + SE_GENI_DMA_MODE_EN);
>> +       if (dma)
>> +               geni_i2c_stop_xfer(gi2c);
> 
> Any reason the if (dma) check isn't inside geni_i2c_stop_xfer()?
> Checking for dma and then bailing out early should work and keep the
> logic in one function. Then the pm_runtime_sync() call could go in 
> there
> too and if (!dma) goto out. This assumes that we're going to call
> geni_i2c_stop_xfer() from somewhere else, like if a transfer times out
> or something?
> 

Okay, will do the changes.

>> +
>> +       pm_runtime_put_sync_suspend(gi2c->se.dev);
>> +}
>> +
>>  static int __maybe_unused geni_i2c_runtime_suspend(struct device 
>> *dev)
>>  {
>>         int ret;
Roja Rani Yarubandi Sept. 7, 2020, 12:53 p.m. UTC | #3 
On 2020-08-26 17:26, Akash Asthana wrote:
> Hi Roja,
> 
> On 8/20/2020 4:05 PM, Roja Rani Yarubandi wrote:
>> If the hardware is still accessing memory after SMMU translation
>> is disabled (as part of smmu shutdown callback), then the
>> IOVAs (I/O virtual address) which it was using will go on the bus
>> as the physical addresses which will result in unknown crashes
>> like NoC/interconnect errors.
>> 
>> So, implement shutdown callback to i2c driver to unmap DMA mappings
>> during system "reboot" or "shutdown".
>> 
>> Signed-off-by: Roja Rani Yarubandi <rojay@codeaurora.org>
>> ---
>> Changes in V2:
>>   - As per Stephen's comments added seperate function for stop 
>> transfer,
>>     fixed minor nitpicks.
>> 
>>   drivers/i2c/busses/i2c-qcom-geni.c | 43 
>> ++++++++++++++++++++++++++++++
>>   include/linux/qcom-geni-se.h       |  5 ++++
>>   2 files changed, 48 insertions(+)
>> 
>> diff --git a/drivers/i2c/busses/i2c-qcom-geni.c 
>> b/drivers/i2c/busses/i2c-qcom-geni.c
>> index 1fda5c7c2cfc..d07f2f33bb75 100644
>> --- a/drivers/i2c/busses/i2c-qcom-geni.c
>> +++ b/drivers/i2c/busses/i2c-qcom-geni.c
>> @@ -486,6 +486,28 @@ static int geni_i2c_xfer(struct i2c_adapter 
>> *adap,
>>   	return ret;
>>   }
>>   +static void geni_i2c_stop_xfer(struct geni_i2c_dev *gi2c)
>> +{
>> +	u32 val;
>> +	struct geni_se *se = &gi2c->se;
>> +
>> +	val = readl_relaxed(gi2c->se.base + SE_DMA_DEBUG_REG0);
>> +	if (val & DMA_TX_ACTIVE) {
>> +		geni_i2c_abort_xfer(gi2c);
>> +		gi2c->cur_wr = 0;
>> +		if (gi2c->err)
>> +			geni_i2c_tx_fsm_rst(gi2c);
>> +		geni_se_tx_dma_unprep(se, gi2c->tx_dma, gi2c->xfer_len);
>> +	}
> should be 'else if', because TX and RX can't happen parallel.
>> +	if (val & DMA_RX_ACTIVE) {
>> +		geni_i2c_abort_xfer(gi2c);
>> +		gi2c->cur_rd = 0;
>> +		if (gi2c->err)
>> +			geni_i2c_rx_fsm_rst(gi2c);
>> +		geni_se_rx_dma_unprep(se, gi2c->rx_dma, gi2c->xfer_len);
>> +	}
>> +}
>> +
>>   static u32 geni_i2c_func(struct i2c_adapter *adap)
>>   {
>>   	return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & 
>> ~I2C_FUNC_SMBUS_QUICK);
>> @@ -617,6 +639,26 @@ static int geni_i2c_remove(struct platform_device 
>> *pdev)
>>   	return 0;
>>   }
>>   +static void geni_i2c_shutdown(struct platform_device *pdev)
>> +{
>> +	int ret;
>> +	u32 dma;
>> +	struct geni_i2c_dev *gi2c = platform_get_drvdata(pdev);
>> +	struct geni_se *se = &gi2c->se;
>> +
>> +	ret = pm_runtime_get_sync(gi2c->se.dev);
>> +	if (ret < 0) {
>> +		dev_err(gi2c->se.dev, "Failed to resume device: %d\n", ret);
>> +		return;
>> +	}
>> +
>> +	dma = readl_relaxed(se->base + SE_GENI_DMA_MODE_EN);
> 
> Wrt to current issue context it may be suffice to stop just DMA mode
> transfers but why not stop all mode of active transfer during shutdown
> in a generic way.
> 
> Regards,
> 
> Akash
> 

Okay, I will include FIFO transfer case also in stop_xfer

>> +	if (dma)
>> +		geni_i2c_stop_xfer(gi2c);
>> +
>> +	pm_runtime_put_sync_suspend(gi2c->se.dev);
>> +}
>> +
>>   static int __maybe_unused geni_i2c_runtime_suspend(struct device 
>> *dev)
>>   {
>>   	int ret;
>> @@ -677,6 +719,7 @@ MODULE_DEVICE_TABLE(of, geni_i2c_dt_match);
>>   static struct platform_driver geni_i2c_driver = {
>>   	.probe  = geni_i2c_probe,
>>   	.remove = geni_i2c_remove,
>> +	.shutdown = geni_i2c_shutdown,
>>   	.driver = {
>>   		.name = "geni_i2c",
>>   		.pm = &geni_i2c_pm_ops,
>> diff --git a/include/linux/qcom-geni-se.h 
>> b/include/linux/qcom-geni-se.h
>> index dd464943f717..c3c016496d98 100644
>> --- a/include/linux/qcom-geni-se.h
>> +++ b/include/linux/qcom-geni-se.h
>> @@ -77,6 +77,7 @@ struct geni_se {
>>   #define SE_DMA_RX_FSM_RST		0xd58
>>   #define SE_HW_PARAM_0			0xe24
>>   #define SE_HW_PARAM_1			0xe28
>> +#define SE_DMA_DEBUG_REG0		0xe40
>>     /* GENI_FORCE_DEFAULT_REG fields */
>>   #define FORCE_DEFAULT	BIT(0)
>> @@ -207,6 +208,10 @@ struct geni_se {
>>   #define RX_GENI_CANCEL_IRQ		BIT(11)
>>   #define RX_GENI_GP_IRQ_EXT		GENMASK(13, 12)
>>   +/* SE_DMA_DEBUG_REG0 Register fields */
>> +#define DMA_TX_ACTIVE			BIT(0)
>> +#define DMA_RX_ACTIVE			BIT(1)
>> +
>>   /* SE_HW_PARAM_0 fields */
>>   #define TX_FIFO_WIDTH_MSK		GENMASK(29, 24)
>>   #define TX_FIFO_WIDTH_SHFT		24