[v6,1/3] i2c: Add Qualcomm CCI I2C driver

This commit adds I2C bus support for the Camera Control Interface
(CCI) I2C controller found on the Qualcomm SoC processors. This I2C
controller supports two masters and they are registered to the core.

CCI versions supported in the driver are msm8916, msm8996 and sdm845.

This is a rework of the patch posted by Vinod:
https://patchwork.kernel.org/patch/10569961/

With additional fixes + most of the comments addressed.

Signed-off-by: Todor Tomov <todor.tomov@linaro.org>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
Tested-by: Robert Foss <robert.foss@linaro.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
---
 v2: Remove clock rates config from driver (done via assigned clock)
     Added CCI timeout recovery from Ricardo's patch:
        https://www.spinics.net/lists/linux-i2c/msg36973.html
 v3: add sdm845 support
     rework cci_init function
 v4: fix checkpatch issue (double semi-colo
 v5: address Bjorn's comment
        Kconfig/Makefile order
        probe/interrupt rework
 v6: Fix exit path (disable_clocks)

 drivers/i2c/busses/Kconfig        |  10 +
 drivers/i2c/busses/Makefile       |   1 +
 drivers/i2c/busses/i2c-qcom-cci.c | 792 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 803 insertions(+)
 create mode 100644 drivers/i2c/busses/i2c-qcom-cci.c

Hi Wolfram,

Thanks for your review, I'm going to send a new version.
See inline comments.

On Sun, 5 Apr 2020 at 19:42, Wolfram Sang <wsa@the-dreams.de> wrote:
>
> Hi Loic,
>
> here are my first comments. Probably not all of them yet, but there are
> some high level questions I wanted to discuss before diving in too deep.
> One more general thing, I think the driver has too much dev_err in it.
> Please keep only the important ones, and turn supplementary ones into
> dev_dbg. Interested users can then enable them.
>
> Thank you for your patience and now for my comments:
>
> On Tue, Mar 10, 2020 at 09:46:59AM +0100, Loic Poulain wrote:
> > This commit adds I2C bus support for the Camera Control Interface
> > (CCI) I2C controller found on the Qualcomm SoC processors. This I2C
> > controller supports two masters and they are registered to the core.
> >
> > CCI versions supported in the driver are msm8916, msm8996 and sdm845.
> >
> > This is a rework of the patch posted by Vinod:
> > https://patchwork.kernel.org/patch/10569961/
> >
> > With additional fixes + most of the comments addressed.
> >
> > Signed-off-by: Todor Tomov <todor.tomov@linaro.org>
> > Signed-off-by: Vinod Koul <vkoul@kernel.org>
> > Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
> > Tested-by: Robert Foss <robert.foss@linaro.org>
> > Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
> > ---
> >  v2: Remove clock rates config from driver (done via assigned clock)
> >      Added CCI timeout recovery from Ricardo's patch:
> >         https://www.spinics.net/lists/linux-i2c/msg36973.html
> >  v3: add sdm845 support
> >      rework cci_init function
> >  v4: fix checkpatch issue (double semi-colo
> >  v5: address Bjorn's comment
> >         Kconfig/Makefile order
> >         probe/interrupt rework
> >  v6: Fix exit path (disable_clocks)
> >
> >  drivers/i2c/busses/Kconfig        |  10 +
> >  drivers/i2c/busses/Makefile       |   1 +
> >  drivers/i2c/busses/i2c-qcom-cci.c | 792 ++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 803 insertions(+)
> >  create mode 100644 drivers/i2c/busses/i2c-qcom-cci.c
> >
> > diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
> > index 6a0aa76..d962671 100644
> > --- a/drivers/i2c/busses/Kconfig
> > +++ b/drivers/i2c/busses/Kconfig
> > @@ -881,6 +881,16 @@ config I2C_PXA_SLAVE
> >         is necessary for systems where the PXA may be a target on the
> >         I2C bus.
> >
> > +config I2C_QCOM_CCI
> > +     tristate "Qualcomm Camera Control Interface"
> > +     depends on ARCH_QCOM || COMPILE_TEST
> > +     help
> > +       If you say yes to this option, support will be included for the
> > +       built-in camera control interface on the Qualcomm SoCs.
> > +
> > +       This driver can also be built as a module.  If so, the module
> > +       will be called i2c-qcom-cci.
> > +
> >  config I2C_QCOM_GENI
> >       tristate "Qualcomm Technologies Inc.'s GENI based I2C controller"
> >       depends on ARCH_QCOM || COMPILE_TEST
> > diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
> > index 3ab8aeb..d8b0788 100644
> > --- a/drivers/i2c/busses/Makefile
> > +++ b/drivers/i2c/busses/Makefile
> > @@ -91,6 +91,7 @@ obj-$(CONFIG_I2C_PNX)               += i2c-pnx.o
> >  obj-$(CONFIG_I2C_PUV3)               += i2c-puv3.o
> >  obj-$(CONFIG_I2C_PXA)                += i2c-pxa.o
> >  obj-$(CONFIG_I2C_PXA_PCI)    += i2c-pxa-pci.o
> > +obj-$(CONFIG_I2C_QCOM_CCI)   += i2c-qcom-cci.o
> >  obj-$(CONFIG_I2C_QCOM_GENI)  += i2c-qcom-geni.o
> >  obj-$(CONFIG_I2C_QUP)                += i2c-qup.o
> >  obj-$(CONFIG_I2C_RIIC)               += i2c-riic.o
> > diff --git a/drivers/i2c/busses/i2c-qcom-cci.c b/drivers/i2c/busses/i2c-qcom-cci.c
> > new file mode 100644
> > index 0000000..9378486
> > --- /dev/null
> > +++ b/drivers/i2c/busses/i2c-qcom-cci.c
> > @@ -0,0 +1,792 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +// Copyright (c) 2012-2016, The Linux Foundation. All rights reserved.
> > +// Copyright (c) 2017-19 Linaro Limited.
> > +
> > +#include <linux/clk.h>
> > +#include <linux/completion.h>
> > +#include <linux/i2c.h>
> > +#include <linux/io.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/pm_runtime.h>
> > +
> > +#define CCI_HW_VERSION                               0x0
> > +#define CCI_RESET_CMD                                0x004
> > +#define CCI_RESET_CMD_MASK                   0x0f73f3f7
> > +#define CCI_RESET_CMD_M0_MASK                        0x000003f1
> > +#define CCI_RESET_CMD_M1_MASK                        0x0003f001
> > +#define CCI_QUEUE_START                              0x008
> > +#define CCI_HALT_REQ                         0x034
> > +#define CCI_HALT_REQ_I2C_M0_Q0Q1             BIT(0)
> > +#define CCI_HALT_REQ_I2C_M1_Q0Q1             BIT(1)
> > +
> > +#define CCI_I2C_Mm_SCL_CTL(m)                        (0x100 + 0x100 * (m))
> > +#define CCI_I2C_Mm_SDA_CTL_0(m)                      (0x104 + 0x100 * (m))
> > +#define CCI_I2C_Mm_SDA_CTL_1(m)                      (0x108 + 0x100 * (m))
> > +#define CCI_I2C_Mm_SDA_CTL_2(m)                      (0x10c + 0x100 * (m))
> > +#define CCI_I2C_Mm_MISC_CTL(m)                       (0x110 + 0x100 * (m))
> > +
> > +#define CCI_I2C_Mm_READ_DATA(m)                      (0x118 + 0x100 * (m))
> > +#define CCI_I2C_Mm_READ_BUF_LEVEL(m)         (0x11c + 0x100 * (m))
> > +#define CCI_I2C_Mm_Qn_EXEC_WORD_CNT(m, n)    (0x300 + 0x200 * (m) + 0x100 * (n))
> > +#define CCI_I2C_Mm_Qn_CUR_WORD_CNT(m, n)     (0x304 + 0x200 * (m) + 0x100 * (n))
> > +#define CCI_I2C_Mm_Qn_CUR_CMD(m, n)          (0x308 + 0x200 * (m) + 0x100 * (n))
> > +#define CCI_I2C_Mm_Qn_REPORT_STATUS(m, n)    (0x30c + 0x200 * (m) + 0x100 * (n))
> > +#define CCI_I2C_Mm_Qn_LOAD_DATA(m, n)                (0x310 + 0x200 * (m) + 0x100 * (n))
> > +
> > +#define CCI_IRQ_GLOBAL_CLEAR_CMD             0xc00
> > +#define CCI_IRQ_MASK_0                               0xc04
> > +#define CCI_IRQ_MASK_0_I2C_M0_RD_DONE                BIT(0)
> > +#define CCI_IRQ_MASK_0_I2C_M0_Q0_REPORT              BIT(4)
> > +#define CCI_IRQ_MASK_0_I2C_M0_Q1_REPORT              BIT(8)
> > +#define CCI_IRQ_MASK_0_I2C_M1_RD_DONE                BIT(12)
> > +#define CCI_IRQ_MASK_0_I2C_M1_Q0_REPORT              BIT(16)
> > +#define CCI_IRQ_MASK_0_I2C_M1_Q1_REPORT              BIT(20)
> > +#define CCI_IRQ_MASK_0_RST_DONE_ACK          BIT(24)
> > +#define CCI_IRQ_MASK_0_I2C_M0_Q0Q1_HALT_ACK  BIT(25)
> > +#define CCI_IRQ_MASK_0_I2C_M1_Q0Q1_HALT_ACK  BIT(26)
> > +#define CCI_IRQ_MASK_0_I2C_M0_ERROR          0x18000ee6
> > +#define CCI_IRQ_MASK_0_I2C_M1_ERROR          0x60ee6000
> > +#define CCI_IRQ_CLEAR_0                              0xc08
> > +#define CCI_IRQ_STATUS_0                     0xc0c
> > +#define CCI_IRQ_STATUS_0_I2C_M0_RD_DONE              BIT(0)
> > +#define CCI_IRQ_STATUS_0_I2C_M0_Q0_REPORT    BIT(4)
> > +#define CCI_IRQ_STATUS_0_I2C_M0_Q1_REPORT    BIT(8)
> > +#define CCI_IRQ_STATUS_0_I2C_M1_RD_DONE              BIT(12)
> > +#define CCI_IRQ_STATUS_0_I2C_M1_Q0_REPORT    BIT(16)
> > +#define CCI_IRQ_STATUS_0_I2C_M1_Q1_REPORT    BIT(20)
> > +#define CCI_IRQ_STATUS_0_RST_DONE_ACK                BIT(24)
> > +#define CCI_IRQ_STATUS_0_I2C_M0_Q0Q1_HALT_ACK        BIT(25)
> > +#define CCI_IRQ_STATUS_0_I2C_M1_Q0Q1_HALT_ACK        BIT(26)
> > +#define CCI_IRQ_STATUS_0_I2C_M0_ERROR                0x18000ee6
> > +#define CCI_IRQ_STATUS_0_I2C_M1_ERROR                0x60ee6000
> > +
> > +#define CCI_TIMEOUT  (msecs_to_jiffies(100))
> > +#define NUM_MASTERS  2
> > +#define NUM_QUEUES   2
> > +
> > +/* Max number of resources + 1 for a NULL terminator */
> > +#define CCI_RES_MAX  6
> > +
> > +#define CCI_I2C_SET_PARAM    1
> > +#define CCI_I2C_REPORT               8
> > +#define CCI_I2C_WRITE                9
> > +#define CCI_I2C_READ         10
> > +
> > +#define CCI_I2C_REPORT_IRQ_EN        BIT(8)
> > +
> > +enum {
> > +     I2C_MODE_STANDARD,
> > +     I2C_MODE_FAST,
> > +     I2C_MODE_FAST_PLUS,
> > +};
> > +
> > +enum cci_i2c_queue_t {
> > +     QUEUE_0,
> > +     QUEUE_1
> > +};
> > +
> > +struct hw_params {
> > +     u16 thigh; /* HIGH period of the SCL clock in clock ticks */
> > +     u16 tlow; /* LOW period of the SCL clock */
> > +     u16 tsu_sto; /* set-up time for STOP condition */
> > +     u16 tsu_sta; /* set-up time for a repeated START condition */
> > +     u16 thd_dat; /* data hold time */
> > +     u16 thd_sta; /* hold time (repeated) START condition */
> > +     u16 tbuf; /* bus free time between a STOP and START condition */
> > +     u8 scl_stretch_en;
> > +     u16 trdhld;
> > +     u16 tsp; /* pulse width of spikes suppressed by the input filter */
> > +};
> > +
> > +struct cci;
> > +
> > +struct cci_master {
> > +     struct i2c_adapter adap;
> > +     u16 master;
> > +     u8 mode;
> > +     int status;
> > +     struct completion irq_complete;
> > +     struct cci *cci;
> > +};
> > +
> > +struct cci_data {
> > +     unsigned int num_masters;
> > +     struct i2c_adapter_quirks quirks;
> > +     u16 queue_size[NUM_QUEUES];
> > +     unsigned long cci_clk_rate;
> > +     struct hw_params params[3];
> > +};
> > +
> > +struct cci {
> > +     struct device *dev;
> > +     void __iomem *base;
> > +     unsigned int irq;
> > +     const struct cci_data *data;
> > +     struct clk_bulk_data *clocks;
> > +     int nclocks;
> > +     struct cci_master master[NUM_MASTERS];
> > +};
> > +
> > +static irqreturn_t cci_isr(int irq, void *dev)
> > +{
> > +     struct cci *cci = dev;
> > +     u32 val, reset = 0;
> > +     int ret = IRQ_NONE;
> > +
> > +     val = readl(cci->base + CCI_IRQ_STATUS_0);
> > +     writel(val, cci->base + CCI_IRQ_CLEAR_0);
> > +     writel(0x1, cci->base + CCI_IRQ_GLOBAL_CLEAR_CMD);
> > +
> > +     if (val & CCI_IRQ_STATUS_0_RST_DONE_ACK) {
> > +             complete(&cci->master[0].irq_complete);
> > +             if (cci->master[1].master)
> > +                     complete(&cci->master[1].irq_complete);
> > +             ret = IRQ_HANDLED;
> > +     }
> > +
> > +     if (val & CCI_IRQ_STATUS_0_I2C_M0_RD_DONE ||
> > +                     val & CCI_IRQ_STATUS_0_I2C_M0_Q0_REPORT ||
> > +                     val & CCI_IRQ_STATUS_0_I2C_M0_Q1_REPORT) {
> > +             cci->master[0].status = 0;
> > +             complete(&cci->master[0].irq_complete);
> > +             ret = IRQ_HANDLED;
> > +     }
> > +
> > +     if (val & CCI_IRQ_STATUS_0_I2C_M1_RD_DONE ||
> > +                     val & CCI_IRQ_STATUS_0_I2C_M1_Q0_REPORT ||
> > +                     val & CCI_IRQ_STATUS_0_I2C_M1_Q1_REPORT) {
> > +             cci->master[1].status = 0;
> > +             complete(&cci->master[1].irq_complete);
> > +             ret = IRQ_HANDLED;
> > +     }
> > +
> > +     if (unlikely(val & CCI_IRQ_STATUS_0_I2C_M0_Q0Q1_HALT_ACK)) {
> > +             reset = CCI_RESET_CMD_M0_MASK;
> > +             ret = IRQ_HANDLED;
> > +     }
> > +
> > +     if (unlikely(val & CCI_IRQ_STATUS_0_I2C_M1_Q0Q1_HALT_ACK)) {
> > +             reset = CCI_RESET_CMD_M1_MASK;
> > +             ret = IRQ_HANDLED;
> > +     }
> > +
> > +     if (unlikely(reset))
> > +             writel(reset, cci->base + CCI_RESET_CMD);
> > +
> > +     if (unlikely(val & CCI_IRQ_STATUS_0_I2C_M0_ERROR)) {
> > +             dev_err_ratelimited(cci->dev, "Master 0 error 0x%08x\n", val);
>
> Hmm, using dev_* in an irq handler...
>
> > +             cci->master[0].status = -EIO;
>
> ... isn't it possible to decipher the error bits further and set
> 'status' according to Documentation/i2c/fault-codes.rst?

Yes will do, I think we can determine if it's due to a nack.

>
> > +             writel(CCI_HALT_REQ_I2C_M0_Q0Q1, cci->base + CCI_HALT_REQ);
> > +             ret = IRQ_HANDLED;
> > +     }
> > +
> > +     if (unlikely(val & CCI_IRQ_STATUS_0_I2C_M1_ERROR)) {
> > +             dev_err_ratelimited(cci->dev, "Master 1 error 0x%08x\n", val);
> > +             cci->master[1].status = -EIO;
> > +             writel(CCI_HALT_REQ_I2C_M1_Q0Q1, cci->base + CCI_HALT_REQ);
> > +             ret = IRQ_HANDLED;
> > +     }
> > +
> > +     return ret;
> > +}
> > +
> > +static int cci_halt(struct cci *cci, u8 master_num)
> > +{
> > +     struct cci_master *master;
> > +     u32 val;
> > +
> > +     if (master_num > 1) {
>
> Is this hardcoded '1' correct? The loop calling this function iterates
> up to 'cci->data->num_masters'.

ack, will fix.

> > +             dev_err(cci->dev, "Unsupported master idx (%u)\n", master_num);
> > +             return -EINVAL;
> > +     }
> > +
> > +     val = BIT(master_num);
> > +     master = &cci->master[master_num];
> > +
> > +     reinit_completion(&master->irq_complete);
> > +     writel(val, cci->base + CCI_HALT_REQ);
> > +
> > +     if (!wait_for_completion_timeout(&master->irq_complete, CCI_TIMEOUT)) {
> > +             dev_err(cci->dev, "CCI halt timeout\n");
>
> Timeouts can happen on the bus. Please don't print if this is a bus
> timeout error.

Yes, this a controller timeout, not a bus one.

> > +             return -ETIMEDOUT;
> > +     }
> > +
> > +     return 0;
> > +}
> > +
> > +static int cci_reset(struct cci *cci)
> > +{
> > +     /*
> > +      * we reset the whole controller, here and for implicity use
> > +      * master[0].xxx for waiting on it.
> > +      */
> > +     reinit_completion(&cci->master[0].irq_complete);
> > +     writel(CCI_RESET_CMD_MASK, cci->base + CCI_RESET_CMD);
> > +
> > +     if (!wait_for_completion_timeout(&cci->master[0].irq_complete,
> > +                                      CCI_TIMEOUT)) {
> > +             dev_err(cci->dev, "CCI reset timeout\n");
> > +             return -ETIMEDOUT;
> > +     }
> > +
> > +     return 0;
> > +}
> > +
> > +static int cci_init(struct cci *cci)
> > +{
> > +     u32 val = CCI_IRQ_MASK_0_I2C_M0_RD_DONE |
> > +                     CCI_IRQ_MASK_0_I2C_M0_Q0_REPORT |
> > +                     CCI_IRQ_MASK_0_I2C_M0_Q1_REPORT |
> > +                     CCI_IRQ_MASK_0_I2C_M1_RD_DONE |
> > +                     CCI_IRQ_MASK_0_I2C_M1_Q0_REPORT |
> > +                     CCI_IRQ_MASK_0_I2C_M1_Q1_REPORT |
> > +                     CCI_IRQ_MASK_0_RST_DONE_ACK |
> > +                     CCI_IRQ_MASK_0_I2C_M0_Q0Q1_HALT_ACK |
> > +                     CCI_IRQ_MASK_0_I2C_M1_Q0Q1_HALT_ACK |
> > +                     CCI_IRQ_MASK_0_I2C_M0_ERROR |
> > +                     CCI_IRQ_MASK_0_I2C_M1_ERROR;
> > +     int i;
> > +
> > +     writel(val, cci->base + CCI_IRQ_MASK_0);
> > +
> > +     for (i = 0; i < cci->data->num_masters; i++) {
> > +             int mode = cci->master[i].mode;
> > +             const struct hw_params *hw;
> > +
> > +             if (!cci->master[i].cci)
> > +                     continue;
> > +
> > +             hw = &cci->data->params[mode];
> > +
> > +             val = hw->thigh << 16 | hw->tlow;
> > +             writel(val, cci->base + CCI_I2C_Mm_SCL_CTL(i));
> > +
> > +             val = hw->tsu_sto << 16 | hw->tsu_sta;
> > +             writel(val, cci->base + CCI_I2C_Mm_SDA_CTL_0(i));
> > +
> > +             val = hw->thd_dat << 16 | hw->thd_sta;
> > +             writel(val, cci->base + CCI_I2C_Mm_SDA_CTL_1(i));
> > +
> > +             val = hw->tbuf;
> > +             writel(val, cci->base + CCI_I2C_Mm_SDA_CTL_2(i));
> > +
> > +             val = hw->scl_stretch_en << 8 | hw->trdhld << 4 | hw->tsp;
> > +             writel(val, cci->base + CCI_I2C_Mm_MISC_CTL(i));
> > +     }
> > +
> > +     return 0;
> > +}
> > +
> > +static int cci_run_queue(struct cci *cci, u8 master, u8 queue)
> > +{
> > +     u32 val;
> > +     int ret;
> > +
> > +     val = readl(cci->base + CCI_I2C_Mm_Qn_CUR_WORD_CNT(master, queue));
> > +     writel(val, cci->base + CCI_I2C_Mm_Qn_EXEC_WORD_CNT(master, queue));
> > +
> > +     reinit_completion(&cci->master[master].irq_complete);
> > +     val = BIT(master * 2 + queue);
> > +     writel(val, cci->base + CCI_QUEUE_START);
> > +
> > +     if (!wait_for_completion_timeout(&cci->master[master].irq_complete,
> > +                                      CCI_TIMEOUT)) {
> > +             dev_err(cci->dev, "master %d queue %d timeout\n",
> > +                     master, queue);
> > +             cci_reset(cci);
> > +             cci_init(cci);
> > +             return -ETIMEDOUT;
> > +     }
> > +
> > +     ret = cci->master[master].status;
> > +     if (ret < 0)
> > +             dev_err(cci->dev, "master %d queue %d error %d\n",
> > +                     master, queue, ret);
> > +
> > +     return ret;
> > +}
> > +
> > +static int cci_validate_queue(struct cci *cci, u8 master, u8 queue)
> > +{
> > +     u32 val;
> > +
> > +     val = readl(cci->base + CCI_I2C_Mm_Qn_CUR_WORD_CNT(master, queue));
> > +     if (val == cci->data->queue_size[queue])
> > +             return -EINVAL;
> > +
> > +     if (!val)
> > +             return 0;
> > +
> > +     val = CCI_I2C_REPORT | CCI_I2C_REPORT_IRQ_EN;
> > +     writel(val, cci->base + CCI_I2C_Mm_Qn_LOAD_DATA(master, queue));
> > +
> > +     return cci_run_queue(cci, master, queue);
> > +}
> > +
> > +static int cci_i2c_read(struct cci *cci, u16 master,
> > +                     u16 addr, u8 *buf, u16 len)
> > +{
> > +     u32 val, words_read, words_exp;
> > +     u8 queue = QUEUE_1;
> > +     int i, index = 0, ret;
> > +     bool first = true;
> > +
> > +     /*
> > +      * Call validate queue to make sure queue is empty before starting.
> > +      * This is to avoid overflow / underflow of queue.
> > +      */
> > +     ret = cci_validate_queue(cci, master, queue);
> > +     if (ret < 0)
> > +             return ret;
> > +
> > +     val = CCI_I2C_SET_PARAM | (addr & 0x7f) << 4;
> > +     writel(val, cci->base + CCI_I2C_Mm_Qn_LOAD_DATA(master, queue));
> > +
> > +     val = CCI_I2C_READ | len << 4;
> > +     writel(val, cci->base + CCI_I2C_Mm_Qn_LOAD_DATA(master, queue));
> > +
> > +     ret = cci_run_queue(cci, master, queue);
> > +     if (ret < 0)
> > +             return ret;
> > +
> > +     words_read = readl(cci->base + CCI_I2C_Mm_READ_BUF_LEVEL(master));
> > +     words_exp = len / 4 + 1;
> > +     if (words_read != words_exp) {
> > +             dev_err(cci->dev, "words read = %d, words expected = %d\n",
> > +                     words_read, words_exp);
> > +             return -EIO;
> > +     }
> > +
> > +     do {
> > +             val = readl(cci->base + CCI_I2C_Mm_READ_DATA(master));
> > +
> > +             for (i = 0; i < 4 && index < len; i++) {
> > +                     if (first) {
> > +                             /* The LS byte of this register represents the
> > +                              * first byte read from the slave during a read
> > +                              * access.
> > +                              */
> > +                             first = false;
> > +                             continue;
> > +                     }
> > +                     buf[index++] = (val >> (i * 8)) & 0xff;
> > +             }
> > +     } while (--words_read);
> > +
> > +     return 0;
> > +}
> > +
> > +static int cci_i2c_write(struct cci *cci, u16 master,
> > +                      u16 addr, u8 *buf, u16 len)
> > +{
> > +     u8 queue = QUEUE_0;
> > +     u8 load[12] = { 0 };
> > +     int i = 0, j, ret;
> > +     u32 val;
> > +
> > +     /*
> > +      * Call validate queue to make sure queue is empty before starting.
> > +      * This is to avoid overflow / underflow of queue.
> > +      */
> > +     ret = cci_validate_queue(cci, master, queue);
> > +     if (ret < 0)
> > +             return ret;
> > +
> > +     val = CCI_I2C_SET_PARAM | (addr & 0x7f) << 4;
> > +     writel(val, cci->base + CCI_I2C_Mm_Qn_LOAD_DATA(master, queue));
> > +
> > +     load[i++] = CCI_I2C_WRITE | len << 4;
> > +
> > +     for (j = 0; j < len; j++)
> > +             load[i++] = buf[j];
> > +
> > +     for (j = 0; j < i; j += 4) {
> > +             val = load[j];
> > +             val |= load[j + 1] << 8;
> > +             val |= load[j + 2] << 16;
> > +             val |= load[j + 3] << 24;
> > +             writel(val, cci->base + CCI_I2C_Mm_Qn_LOAD_DATA(master, queue));
> > +     }
> > +
> > +     val = CCI_I2C_REPORT | CCI_I2C_REPORT_IRQ_EN;
> > +     writel(val, cci->base + CCI_I2C_Mm_Qn_LOAD_DATA(master, queue));
> > +
> > +     return cci_run_queue(cci, master, queue);
> > +}
> > +
> > +static int cci_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
> > +{
> > +     struct cci_master *cci_master = i2c_get_adapdata(adap);
> > +     struct cci *cci = cci_master->cci;
> > +     int i, ret;
> > +
> > +     ret = pm_runtime_get_sync(cci->dev);
> > +     if (ret < 0)
> > +             goto err;
> > +
> > +     for (i = 0; i < num; i++) {
> > +             if (msgs[i].flags & I2C_M_RD)
> > +                     ret = cci_i2c_read(cci, cci_master->master,
> > +                                        msgs[i].addr, msgs[i].buf,
> > +                                        msgs[i].len);
> > +             else
> > +                     ret = cci_i2c_write(cci, cci_master->master,
> > +                                         msgs[i].addr, msgs[i].buf,
> > +                                         msgs[i].len);
> > +
> > +             if (ret < 0)
> > +                     break;
> > +     }
> > +
> > +     if (!ret)
> > +             ret = num;
> > +
> > +err:
> > +     pm_runtime_mark_last_busy(cci->dev);
> > +     pm_runtime_put_autosuspend(cci->dev);
> > +
> > +     return ret;
> > +}
> > +
> > +static u32 cci_func(struct i2c_adapter *adap)
> > +{
> > +     return I2C_FUNC_I2C;
> > +}
>
> Even with the quirks, I think this HW is able to support
> I2C_FUNC_SMBUS_BYTE | I2C_FUNC_SMBUS_BYTE_DATA |
> I2C_FUNC_SMBUS_WORD_DATA via the I2C core SMBus emulation code.

Can be achieved by reporting I2C_FUNC_SMBUS_EMUL, right?

> > +
> > +static const struct i2c_algorithm cci_algo = {
> > +     .master_xfer    = cci_xfer,
> > +     .functionality  = cci_func,
> > +};
> > +
> > +static int cci_enable_clocks(struct cci *cci)
> > +{
> > +     return clk_bulk_prepare_enable(cci->nclocks, cci->clocks);
> > +}
> > +
> > +static void cci_disable_clocks(struct cci *cci)
> > +{
> > +     clk_bulk_disable_unprepare(cci->nclocks, cci->clocks);
> > +}
> > +
> > +static int __maybe_unused cci_suspend_runtime(struct device *dev)
> > +{
> > +     struct cci *cci = dev_get_drvdata(dev);
> > +
> > +     dev_dbg(dev, "Supend invoked\n");
>
> This and the next dev_dbg should go, the PM cores should have printouts
> for that.

ack.

> > +     cci_disable_clocks(cci);
> > +     return 0;
> > +}
> > +
> > +static int __maybe_unused cci_resume_runtime(struct device *dev)
> > +{
> > +     struct cci *cci = dev_get_drvdata(dev);
> > +     int ret;
> > +
> > +     dev_dbg(dev, "Resume invoked\n");
> > +     ret = cci_enable_clocks(cci);
> > +     if (ret)
> > +             return ret;
> > +
> > +     cci_init(cci);
> > +     return 0;
> > +}
> > +
> > +static int __maybe_unused cci_suspend(struct device *dev)
> > +{
> > +     if (!pm_runtime_suspended(dev))
> > +             return cci_suspend_runtime(dev);
> > +
> > +     return 0;
> > +}
> > +
> > +static int __maybe_unused cci_resume(struct device *dev)
> > +{
> > +     cci_resume_runtime(dev);
> > +     pm_runtime_mark_last_busy(dev);
> > +     pm_request_autosuspend(dev);
> > +
> > +     return 0;
> > +}
> > +
> > +static const struct dev_pm_ops qcom_cci_pm = {
> > +     SET_SYSTEM_SLEEP_PM_OPS(cci_suspend, cci_resume)
> > +     SET_RUNTIME_PM_OPS(cci_suspend_runtime, cci_resume_runtime, NULL)
> > +};
> > +
> > +static int cci_probe(struct platform_device *pdev)
> > +{
> > +     struct device *dev = &pdev->dev;
> > +     unsigned long cci_clk_rate = 0;
> > +     struct device_node *child;
> > +     struct resource *r;
> > +     struct cci *cci;
> > +     int ret, i;
> > +     u32 val;
> > +
> > +     cci = devm_kzalloc(dev, sizeof(*cci), GFP_KERNEL);
> > +     if (!cci)
> > +             return -ENOMEM;
> > +
> > +     cci->dev = dev;
> > +     platform_set_drvdata(pdev, cci);
> > +     cci->data = device_get_match_data(dev);
> > +     if (!cci->data) {
> > +             dev_err(dev, "Driver data is null, abort\n");
> > +             return -EIO;
>
> Minor nit: I think this happens only during development, so I'd think
> returning something like -ENOENT is distinguishable enough to drop the
> error message.

ack.

>
> > +     }
> > +
> > +     for_each_available_child_of_node(dev->of_node, child) {
> > +             u32 idx;
> > +
> > +             ret = of_property_read_u32(child, "reg", &idx);
> > +             if (ret) {
> > +                     dev_err(dev, "%pOF invalid 'reg' property", child);
> > +                     continue;
> > +             }
> > +
> > +             if (idx >= cci->data->num_masters) {
> > +                     dev_err(dev, "%pOF invalid 'reg' value: %u (max is %u)",
> > +                             child, idx, cci->data->num_masters - 1);
> > +                     continue;
> > +             }
> > +
> > +             cci->master[idx].adap.quirks = &cci->data->quirks;
> > +             cci->master[idx].adap.algo = &cci_algo;
> > +             cci->master[idx].adap.dev.parent = dev;
> > +             cci->master[idx].adap.dev.of_node = child;
> > +             cci->master[idx].master = idx;
> > +             cci->master[idx].cci = cci;
> > +
> > +             i2c_set_adapdata(&cci->master[idx].adap, &cci->master[idx]);
> > +             snprintf(cci->master[idx].adap.name,
> > +                      sizeof(cci->master[idx].adap.name),
> > +                      "Qualcomm Camera Control Interface: %d", idx);
>
> With I2C_NAME_SIZE being 20, I don't think this will work. Did you
> verify?

i2c_adapter name is a 48-byte string, but I agree that this quite a
long name, will change that.

>> > +
> > +             cci->master[idx].mode = I2C_MODE_STANDARD;
> > +             ret = of_property_read_u32(child, "clock-frequency", &val);
> > +             if (!ret) {
> > +                     if (val == 400000)
> > +                             cci->master[idx].mode = I2C_MODE_FAST;
> > +                     else if (val == 1000000)
> > +                             cci->master[idx].mode = I2C_MODE_FAST_PLUS;
> > +             }
> > +
> > +             init_completion(&cci->master[idx].irq_complete);
> > +     }
> > +
> > +     /* Memory */
> > +
> > +     r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > +     cci->base = devm_ioremap_resource(dev, r);
> > +     if (IS_ERR(cci->base))
> > +             return PTR_ERR(cci->base);
> > +
> > +     /* Clocks */
> > +
> > +     ret = devm_clk_bulk_get_all(dev, &cci->clocks);
> > +     if (ret < 1) {
> > +             dev_err(dev, "failed to get clocks %d\n", ret);
> > +             return ret;
> > +     }
> > +     cci->nclocks = ret;
> > +
> > +     /* Retrieve CCI clock rate */
> > +     for (i = 0; i < cci->nclocks; i++) {
> > +             if (!strcmp(cci->clocks[i].id, "cci")) {
> > +                     cci_clk_rate = clk_get_rate(cci->clocks[i].clk);
> > +                     break;
> > +             }
> > +     }
> > +
> > +     if (cci_clk_rate != cci->data->cci_clk_rate) {
> > +             /* cci clock set by the bootloader or via assigned clock rate
> > +              * in DT.
> > +              */
> > +             dev_warn(dev, "Found %lu cci clk rate while %lu was expected\n",
> > +                      cci_clk_rate, cci->data->cci_clk_rate);
> > +     }
> > +
> > +     ret = cci_enable_clocks(cci);
> > +     if (ret < 0)
> > +             return ret;
> > +
> > +     /* Interrupt */
> > +
> > +     ret = platform_get_irq(pdev, 0);
> > +     if (ret < 0) {
> > +             dev_err(dev, "missing IRQ: %d\n", ret);
> > +             goto disable_clocks;
> > +     }
> > +     cci->irq = ret;
> > +
> > +     ret = devm_request_irq(dev, cci->irq, cci_isr, 0, dev_name(dev), cci);
> > +     if (ret < 0) {
> > +             dev_err(dev, "request_irq failed, ret: %d\n", ret);
> > +             goto disable_clocks;
> > +     }
> > +
> > +     val = readl(cci->base + CCI_HW_VERSION);
> > +     dev_dbg(dev, "CCI HW version = 0x%08x", val);
> > +
> > +     ret = cci_reset(cci);
> > +     if (ret < 0)
> > +             goto error;
> > +
> > +     ret = cci_init(cci);
> > +     if (ret < 0)
> > +             goto error;
> > +
> > +     for (i = 0; i < cci->data->num_masters; i++) {
> > +             if (!cci->master[i].cci)
> > +                     continue;
> > +
> > +             ret = i2c_add_adapter(&cci->master[i].adap);
> > +             if (ret < 0)
> > +                     goto error_i2c;
> > +     }
> > +
> > +     pm_runtime_set_autosuspend_delay(dev, MSEC_PER_SEC);
> > +     pm_runtime_use_autosuspend(dev);
> > +     pm_runtime_set_active(dev);
> > +     pm_runtime_enable(dev);
> > +
> > +     return 0;
> > +
> > +error_i2c:
> > +     for (; i >= 0; i--) {
> > +             if (cci->master[i].cci)
> > +                     i2c_del_adapter(&cci->master[i].adap);
> > +     }
> > +error:
> > +     disable_irq(cci->irq);
> > +disable_clocks:
> > +     cci_disable_clocks(cci);
> > +
> > +     return ret;
> > +}
> > +
> > +static int cci_remove(struct platform_device *pdev)
> > +{
> > +     struct cci *cci = platform_get_drvdata(pdev);
> > +     int i;
> > +
> > +     for (i = 0; i < cci->data->num_masters; i++) {
> > +             if (cci->master[i].cci)
> > +                     i2c_del_adapter(&cci->master[i].adap);
> > +             cci_halt(cci, i);
> > +     }
> > +
> > +     disable_irq(cci->irq);
> > +     pm_runtime_disable(&pdev->dev);
> > +     pm_runtime_set_suspended(&pdev->dev);
> > +
> > +     return 0;
> > +}
> > +
> > +static const struct cci_data cci_v1_data = {
> > +     .num_masters = 1,
> > +     .queue_size = { 64, 16 },
> > +     .quirks = {
> > +             .max_write_len = 10,
> > +             .max_read_len = 12,
> > +     },
> > +     .cci_clk_rate =  19200000,
> > +     .params[I2C_MODE_STANDARD] = {
> > +             .thigh = 78,
> > +             .tlow = 114,
> > +             .tsu_sto = 28,
> > +             .tsu_sta = 28,
> > +             .thd_dat = 10,
> > +             .thd_sta = 77,
> > +             .tbuf = 118,
> > +             .scl_stretch_en = 0,
> > +             .trdhld = 6,
> > +             .tsp = 1
> > +     },
> > +     .params[I2C_MODE_FAST] = {
> > +             .thigh = 20,
> > +             .tlow = 28,
> > +             .tsu_sto = 21,
> > +             .tsu_sta = 21,
> > +             .thd_dat = 13,
> > +             .thd_sta = 18,
> > +             .tbuf = 32,
> > +             .scl_stretch_en = 0,
> > +             .trdhld = 6,
> > +             .tsp = 3
> > +     },
> > +};
> > +
> > +static const struct cci_data cci_v2_data = {
> > +     .num_masters = 2,
> > +     .queue_size = { 64, 16 },
> > +     .quirks = {
> > +             .max_write_len = 11,
> > +             .max_read_len = 12,
> > +     },
> > +     .cci_clk_rate =  37500000,
> > +     .params[I2C_MODE_STANDARD] = {
> > +             .thigh = 201,
> > +             .tlow = 174,
> > +             .tsu_sto = 204,
> > +             .tsu_sta = 231,
> > +             .thd_dat = 22,
> > +             .thd_sta = 162,
> > +             .tbuf = 227,
> > +             .scl_stretch_en = 0,
> > +             .trdhld = 6,
> > +             .tsp = 3
> > +     },
> > +     .params[I2C_MODE_FAST] = {
> > +             .thigh = 38,
> > +             .tlow = 56,
> > +             .tsu_sto = 40,
> > +             .tsu_sta = 40,
> > +             .thd_dat = 22,
> > +             .thd_sta = 35,
> > +             .tbuf = 62,
> > +             .scl_stretch_en = 0,
> > +             .trdhld = 6,
> > +             .tsp = 3
> > +     },
> > +     .params[I2C_MODE_FAST_PLUS] = {
> > +             .thigh = 16,
> > +             .tlow = 22,
> > +             .tsu_sto = 17,
> > +             .tsu_sta = 18,
> > +             .thd_dat = 16,
> > +             .thd_sta = 15,
> > +             .tbuf = 24,
> > +             .scl_stretch_en = 0,
> > +             .trdhld = 3,
> > +             .tsp = 3
> > +     },
> > +};
>
> These params, can't they be calculated to allow for other frequencies
> than 100kHz, 400kHz,...?

Well, it should be possible, but not sure the calculation would be
straightforward, these values have been fine-tuned (retrieved from the
downstream driver). This is not something I can test and validate
right now.

> > +
> > +static const struct of_device_id cci_dt_match[] = {
> > +     { .compatible = "qcom,msm8916-cci", .data = &cci_v1_data},
> > +     { .compatible = "qcom,msm8996-cci", .data = &cci_v2_data},
> > +     { .compatible = "qcom,sdm845-cci", .data = &cci_v2_data},
> > +     {}
> > +};
> > +MODULE_DEVICE_TABLE(of, cci_dt_match);
> > +
> > +static struct platform_driver qcom_cci_driver = {
> > +     .probe  = cci_probe,
> > +     .remove = cci_remove,
> > +     .driver = {
> > +             .name = "i2c-qcom-cci",
> > +             .of_match_table = cci_dt_match,
> > +             .pm = &qcom_cci_pm,
> > +     },
> > +};
> > +
> > +module_platform_driver(qcom_cci_driver);
> > +
> > +MODULE_DESCRIPTION("Qualcomm Camera Control Interface driver");
> > +MODULE_AUTHOR("Todor Tomov <todor.tomov@linaro.org>");
> > +MODULE_AUTHOR("Loic Poulain <loic.poulain@linaro.org>");
> > +MODULE_LICENSE("GPL v2");
> > --
> > 2.7.4
> >