Re: [PATCH v10 4/4] i2c: core: support bus regulator controlling in adapter

[Tomasz Figa <tfiga@chromium.org>]

On Thu, Jan 16, 2020 at 11:56 AM Bibby Hsieh <bibby.hsieh@mediatek.com> wrote:
>
> Although in the most platforms, the bus power of i2c
> are alway on, some platforms disable the i2c bus power
> in order to meet low power request.
>
> We get and enable bulk regulator in i2c adapter device.
>
> Signed-off-by: Bibby Hsieh <bibby.hsieh@mediatek.com>
> ---
>  drivers/i2c/i2c-core-base.c | 81 +++++++++++++++++++++++++++++++++++++
>  include/linux/i2c.h         |  3 ++
>  2 files changed, 84 insertions(+)
>

Hi Bibby,

Please see my comments inline.

Hi Wolfram,

Would you have some time to take a look and comment on the general
approach? Thanks.

> diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
> index 9333c865d4a9..9b9e96b094ca 100644
> --- a/drivers/i2c/i2c-core-base.c
> +++ b/drivers/i2c/i2c-core-base.c
> @@ -306,6 +306,7 @@ static int i2c_smbus_host_notify_to_irq(const struct i2c_client *client)
>  static int i2c_device_probe(struct device *dev)
>  {
>         struct i2c_client       *client = i2c_verify_client(dev);
> +       struct i2c_adapter      *adap = client->adapter;
>         struct i2c_driver       *driver;
>         int status;
>
> @@ -371,6 +372,12 @@ static int i2c_device_probe(struct device *dev)
>
>         dev_dbg(dev, "probe\n");
>
> +       status = regulator_enable(adap->bus_reg);
> +       if (status != 0) {
> +               dev_err(&adap->dev, "Failed to enable power regulator\n");
> +               goto err_clear_wakeup_irq;
> +       }
> +
>         status = of_clk_set_defaults(dev->of_node, false);
>         if (status < 0)
>                 goto err_clear_wakeup_irq;
> @@ -407,6 +414,7 @@ static int i2c_device_probe(struct device *dev)
>  static int i2c_device_remove(struct device *dev)
>  {
>         struct i2c_client       *client = i2c_verify_client(dev);
> +       struct i2c_adapter      *adap = client->adapter;
>         struct i2c_driver       *driver;
>         int status = 0;
>
> @@ -420,6 +428,8 @@ static int i2c_device_remove(struct device *dev)
>         }
>
>         dev_pm_domain_detach(&client->dev, true);
> +       if (!pm_runtime_status_suspended(&adap->dev))

Why adap->dev? We control the regulator in bus-level runtime PM
callbacks of the client->dev, right?

> +               regulator_disable(adap->bus_reg);
>
>         dev_pm_clear_wake_irq(&client->dev);
>         device_init_wakeup(&client->dev, false);
> @@ -431,6 +441,71 @@ static int i2c_device_remove(struct device *dev)
>         return status;
>  }
>
> +#ifdef CONFIG_PM_SLEEP
> +static int i2c_resume(struct device *dev)
> +{
> +       struct i2c_client *client = i2c_verify_client(dev);
> +       struct i2c_adapter *adap = client->adapter;
> +       int err;
> +
> +       if (pm_runtime_status_suspended(&adap->dev)) {

Ditto.

> +               err = regulator_enable(adap->bus_reg);
> +               if (err)
> +                       return err;
> +       }
> +
> +       return pm_generic_resume(dev);
> +}
> +
> +static int i2c_suspend(struct device *dev)
> +{
> +       struct i2c_client *client = i2c_verify_client(dev);
> +       struct i2c_adapter *adap = client->adapter;
> +       int err;
> +
> +       if (!pm_runtime_status_suspended(&adap->dev)) {

Ditto.

> +               err = regulator_disable(adap->bus_reg);
> +               if (err)
> +                       return err;
> +       }
> +
> +       return pm_generic_suspend(dev);
> +}
> +#endif
> +
> +#ifdef CONFIG_PM
> +static int i2c_runtime_resume(struct device *dev)
> +{
> +       struct i2c_client *client = i2c_verify_client(dev);
> +       struct i2c_adapter *adap = client->adapter;
> +       int err;
> +
> +       err = regulator_enable(adap->bus_reg);
> +       if (err)
> +               return err;
> +
> +       return pm_generic_runtime_resume(dev);
> +}
> +
> +static int i2c_runtime_suspend(struct device *dev)
> +{
> +       struct i2c_client *client = i2c_verify_client(dev);
> +       struct i2c_adapter *adap = client->adapter;
> +       int err;
> +
> +       err = pm_generic_runtime_suspend(dev);
> +       if (err)
> +               return err;
> +
> +       return regulator_disable(adap->bus_reg);
> +}
> +#endif
> +
> +static const struct dev_pm_ops i2c_device_pm = {
> +       SET_SYSTEM_SLEEP_PM_OPS(i2c_suspend, i2c_resume)
> +       SET_RUNTIME_PM_OPS(i2c_runtime_suspend, i2c_runtime_resume, NULL)
> +};
> +
>  static void i2c_device_shutdown(struct device *dev)
>  {
>         struct i2c_client *client = i2c_verify_client(dev);
> @@ -488,6 +563,7 @@ struct bus_type i2c_bus_type = {
>         .probe          = i2c_device_probe,
>         .remove         = i2c_device_remove,
>         .shutdown       = i2c_device_shutdown,
> +       .pm             = &i2c_device_pm,
>  };
>  EXPORT_SYMBOL_GPL(i2c_bus_type);
>
> @@ -1351,6 +1427,11 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
>                 goto out_reg;
>
>         dev_dbg(&adap->dev, "adapter [%s] registered\n", adap->name);
> +       adap->bus_reg = devm_regulator_get(&adap->dev, "bus");
> +       if (IS_ERR(adap->bus_reg)) {
> +               res = PTR_ERR(adap->bus_reg);
> +               goto out_reg;
> +       }
>
>         pm_runtime_no_callbacks(&adap->dev);
>         pm_suspend_ignore_children(&adap->dev, true);
> diff --git a/include/linux/i2c.h b/include/linux/i2c.h
> index d2f786706657..833b81a680da 100644
> --- a/include/linux/i2c.h
> +++ b/include/linux/i2c.h
> @@ -15,6 +15,7 @@
>  #include <linux/device.h>      /* for struct device */
>  #include <linux/sched.h>       /* for completion */
>  #include <linux/mutex.h>
> +#include <linux/regulator/consumer.h>
>  #include <linux/rtmutex.h>
>  #include <linux/irqdomain.h>           /* for Host Notify IRQ */
>  #include <linux/of.h>          /* for struct device_node */
> @@ -330,6 +331,7 @@ struct i2c_client {
>         int init_irq;                   /* irq set at initialization    */
>         int irq;                        /* irq issued by device         */
>         struct list_head detected;
> +

nit: Unnecessary change.

Best regards,
Tomasz