Re: [PATCH] i2c: designware-platdrv: implement bus recovery

[Martinez Kristofer]

On Thu, Apr 14, 2016 at 10:39 PM, Mika Westerberg
<mika.westerberg@xxxxxxxxxxxxxxx> wrote:
> On Thu, Apr 14, 2016 at 10:04:56PM +0800, Jisheng Zhang wrote:
>> Implement bus recovery methods for i2c designware so we can recover
>> from situations where SCL/SDA are stuck low.
>>
>> The recovery method is similar as i2c-imx: "config the i2c pinctrl to
>> gpio mode by calling pinctrl sleep set function, and then use GPIO to
>> emulate the i2c protocol to send nine dummy clock to recover i2c
>> device. After recovery, set i2c pinctrl to default group setting.
>>
>> Signed-off-by: Jisheng Zhang <jszhang@xxxxxxxxxxx>
>> ---
>> depends on runtime pm patches
>> http://lists.infradead.org/pipermail/linux-arm-kernel/2016-April/422202.html
>>  .../devicetree/bindings/i2c/i2c-designware.txt     | 12 ++++++
>>  drivers/i2c/busses/i2c-designware-core.c           |  6 ++-
>>  drivers/i2c/busses/i2c-designware-core.h           |  4 ++
>>  drivers/i2c/busses/i2c-designware-platdrv.c        | 50 ++++++++++++++++++++++
>>  4 files changed, 71 insertions(+), 1 deletion(-)
>>
>> diff --git a/Documentation/devicetree/bindings/i2c/i2c-designware.txt b/Documentation/devicetree/bindings/i2c/i2c-designware.txt
>> index fee26dc..51a55c6 100644
>> --- a/Documentation/devicetree/bindings/i2c/i2c-designware.txt
>> +++ b/Documentation/devicetree/bindings/i2c/i2c-designware.txt
>> @@ -20,6 +20,13 @@ Optional properties :
>>   - i2c-sda-falling-time-ns : should contain the SDA falling time in nanoseconds.
>>     This value which is by default 300ns is used to compute the tHIGH period.
>>
>> + - scl-gpios: specify the gpio related to SCL pin
>> +
>> + - sda-gpios: specify the gpio related to SDA pin
>> +
>> + - pinctrl: add extra pinctrl to configure i2c pins to gpio function for i2c
>> +   bus recovery, call it "gpio" state
>> +
>>  Example :
>>
>>       i2c@f0000 {
>> @@ -42,4 +49,9 @@ Example :
>>               i2c-sda-hold-time-ns = <300>;
>>               i2c-sda-falling-time-ns = <300>;
>>               i2c-scl-falling-time-ns = <300>;
>> +             pinctrl-names = "default", "gpio";
>> +             pinctrl-0 = <&pinctrl_i2c1_default>;
>> +             pinctrl-1 = <&pinctrl_i2c1_gpio>;
>> +             scl-gpios = <&porta 26 GPIO_ACTIVE_HIGH>;
>> +             sda-gpios = <&porta 27 GPIO_ACTIVE_HIGH>;
>>       };
>> diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c
>> index 4255eaa..be40de1 100644
>> --- a/drivers/i2c/busses/i2c-designware-core.c
>> +++ b/drivers/i2c/busses/i2c-designware-core.c
>> @@ -399,7 +399,10 @@ static int i2c_dw_wait_bus_not_busy(struct dw_i2c_dev *dev)
>>       while (dw_readl(dev, DW_IC_STATUS) & DW_IC_STATUS_ACTIVITY) {
>>               if (timeout <= 0) {
>>                       dev_warn(dev->dev, "timeout waiting for bus ready\n");
>> -                     return -ETIMEDOUT;
>> +                     i2c_recover_bus(&dev->adapter);
>> +                     if (dw_readl(dev, DW_IC_STATUS)
>> +                                     & DW_IC_STATUS_ACTIVITY)
>> +                             return -ETIMEDOUT;
>>               }
>>               timeout--;
>>               usleep_range(1000, 1100);
>> @@ -665,6 +668,7 @@ i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
>>       /* wait for tx to complete */
>>       if (!wait_for_completion_timeout(&dev->cmd_complete, HZ)) {
>>               dev_err(dev->dev, "controller timed out\n");
>> +             i2c_recover_bus(&dev->adapter);
>>               /* i2c_dw_init implicitly disables the adapter */
>>               i2c_dw_init(dev);
>>               ret = -ETIMEDOUT;
>> diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
>> index cd409e7..26c84ee 100644
>> --- a/drivers/i2c/busses/i2c-designware-core.h
>> +++ b/drivers/i2c/busses/i2c-designware-core.h
>> @@ -104,6 +104,10 @@ struct dw_i2c_dev {
>>       u16                     fs_lcnt;
>>       int                     (*acquire_lock)(struct dw_i2c_dev *dev);
>>       void                    (*release_lock)(struct dw_i2c_dev *dev);
>> +     struct i2c_bus_recovery_info rinfo;
>> +     struct pinctrl          *pinctrl;
>> +     struct pinctrl_state    *pinctrl_pins_default;
>> +     struct pinctrl_state    *pinctrl_pins_gpio;
>>       bool                    pm_runtime_disabled;
>>  };
>>
>> diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
>> index 1488cea..62bded9 100644
>> --- a/drivers/i2c/busses/i2c-designware-platdrv.c
>> +++ b/drivers/i2c/busses/i2c-designware-platdrv.c
>> @@ -33,6 +33,7 @@
>>  #include <linux/err.h>
>>  #include <linux/interrupt.h>
>>  #include <linux/of.h>
>> +#include <linux/of_gpio.h>
>>  #include <linux/platform_device.h>
>>  #include <linux/pm.h>
>>  #include <linux/pm_runtime.h>
>> @@ -148,6 +149,49 @@ static int i2c_dw_plat_prepare_clk(struct dw_i2c_dev *i_dev, bool prepare)
>>       return 0;
>>  }
>>
>> +static void i2c_dw_plat_prepare_recovery(struct i2c_adapter *adap)
>> +{
>> +     struct dw_i2c_dev *dev = i2c_get_adapdata(adap);
>> +
>> +     pinctrl_select_state(dev->pinctrl, dev->pinctrl_pins_gpio);
>> +}
>> +
>> +static void i2c_dw_plat_unprepare_recovery(struct i2c_adapter *adap)
>> +{
>> +     struct dw_i2c_dev *dev = i2c_get_adapdata(adap);
>> +
>> +     pinctrl_select_state(dev->pinctrl, dev->pinctrl_pins_default);
>> +}
>> +
>> +static void i2c_dw_plat_init_recovery_info(struct dw_i2c_dev *dev,
>> +                                        struct platform_device *pdev)
>> +{
>> +     struct i2c_bus_recovery_info *rinfo = &dev->rinfo;
>> +
>> +     dev->pinctrl_pins_default = pinctrl_lookup_state(dev->pinctrl,
>> +                     PINCTRL_STATE_DEFAULT);
>> +     dev->pinctrl_pins_gpio = pinctrl_lookup_state(dev->pinctrl,
>> +                     "gpio");
>> +     rinfo->sda_gpio = of_get_named_gpio(pdev->dev.of_node, "sda-gpios", 0);
>> +     rinfo->scl_gpio = of_get_named_gpio(pdev->dev.of_node, "scl-gpios", 0);
>> +
>> +     if (!gpio_is_valid(rinfo->sda_gpio) ||
>> +         !gpio_is_valid(rinfo->scl_gpio) ||
>> +         IS_ERR(dev->pinctrl_pins_default) ||
>> +         IS_ERR(dev->pinctrl_pins_gpio)) {
>> +             dev_dbg(&pdev->dev, "recovery information incomplete\n");
>> +             return;
>> +     }
>> +
>> +     dev_dbg(&pdev->dev, "using scl-gpio %d and sda-gpio %d for recovery\n",
>> +             rinfo->sda_gpio, rinfo->scl_gpio);
>> +
>> +     rinfo->prepare_recovery = i2c_dw_plat_prepare_recovery;
>> +     rinfo->unprepare_recovery = i2c_dw_plat_unprepare_recovery;
>> +     rinfo->recover_bus = i2c_generic_gpio_recovery;
>
> This whole thing is DT specific and I don't see how we can do the same
> for ACPI. Should it be enabled only when the controller was enumerated
> from DT?
>
For ACPI, probably result in the panic-alike function calling chain at
i2c_dw_init --> dev->get_clk_rate_khz(dev).
Mika, I think you need to take ACPI into account while not focus on DT only

KM

>> +     dev->adapter.bus_recovery_info = rinfo;
>> +}
>> +
>>  static int dw_i2c_plat_probe(struct platform_device *pdev)
>>  {
>>       struct dw_i2c_platform_data *pdata = dev_get_platdata(&pdev->dev);
>> @@ -165,6 +209,12 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
>>       if (!dev)
>>               return -ENOMEM;
>>
>> +     dev->pinctrl = devm_pinctrl_get(&pdev->dev);
>> +     if (IS_ERR(dev->pinctrl))
>> +             return PTR_ERR(dev->pinctrl);
>> +
>> +     i2c_dw_plat_init_recovery_info(dev, pdev);
>> +
>>       mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>>       dev->base = devm_ioremap_resource(&pdev->dev, mem);
>>       if (IS_ERR(dev->base))
>> --
>> 2.8.0.rc3
>
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