linux-kernel - Re: [PATCH v10 5/7] i2c: of-prober: Add GPIO support to simple helpers

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Message-ID: <ZypER5bqLAlH7VxK@skv.local>
Date: Tue, 5 Nov 2024 19:13:59 +0300
From: Andrey Skvortsov <andrej.skvortzov@...il.com>
To: Chen-Yu Tsai <wenst@...omium.org>
Cc: Rob Herring <robh@...nel.org>, Saravana Kannan <saravanak@...gle.com>,
	Matthias Brugger <matthias.bgg@...il.com>,
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
	Wolfram Sang <wsa@...nel.org>, Benson Leung <bleung@...omium.org>,
	Tzung-Bi Shih <tzungbi@...nel.org>, chrome-platform@...ts.linux.dev,
	devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Douglas Anderson <dianders@...omium.org>,
	Johan Hovold <johan@...nel.org>, Jiri Kosina <jikos@...nel.org>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	linux-i2c@...r.kernel.org
Subject: Re: [PATCH v10 5/7] i2c: of-prober: Add GPIO support to simple
 helpers

On 24-10-30 15:22, Chen-Yu Tsai wrote:
> Add GPIO support to the simple helpers for the I2C OF component prober.
> Components that the prober intends to probe likely require their
> regulator supplies be enabled, and GPIOs be toggled to enable them or
> bring them out of reset before they will respond to probe attempts.
> Regulator supplies were handled in the previous patch.
> 
> The assumption is that the same class of components to be probed are
> always connected in the same fashion with the same regulator supply
> and GPIO. The names may vary due to binding differences, but the
> physical layout does not change.
> 
> This supports at most one GPIO pin. The user must specify the GPIO name,
> the polarity, and the amount of time to wait after the GPIO is toggled.
> Devices with more than one GPIO pin likely require specific power
> sequencing beyond what generic code can easily support.
> 
> Signed-off-by: Chen-Yu Tsai <wenst@...omium.org>
> Reviewed-by: Douglas Anderson <dianders@...omium.org>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---

> diff --git a/include/linux/i2c-of-prober.h b/include/linux/i2c-of-prober.h
> index df95aa6ad90e..a232f3cbb252 100644
> --- a/include/linux/i2c-of-prober.h
> +++ b/include/linux/i2c-of-prober.h
> @@ -85,6 +85,7 @@ int i2c_of_probe_component(struct device *dev, const struct i2c_of_probe_cfg *cf
>   *
>   * The following helpers are provided:
>   * * i2c_of_probe_simple_enable()
> + * * i2c_of_probe_simple_cleanup_early()
>   * * i2c_of_probe_simple_cleanup()
>   */
>  
> @@ -92,14 +93,31 @@ int i2c_of_probe_component(struct device *dev, const struct i2c_of_probe_cfg *cf
>   * struct i2c_of_probe_simple_opts - Options for simple I2C component prober callbacks
>   * @res_node_compatible: Compatible string of device node to retrieve resources from.
>   * @supply_name: Name of regulator supply.
> + * @gpio_name: Name of GPIO. NULL if no GPIO line is used. Empty string ("") if GPIO
> + *	       line is unnamed.
>   * @post_power_on_delay_ms: Delay after regulators are powered on. Passed to msleep().
> + * @post_gpio_config_delay_ms: Delay after GPIO is configured. Passed to msleep().
> + * @gpio_assert_to_enable: %true if GPIO should be asserted, i.e. set to logical high,
> + *			   to enable the component.
> + *
> + * This describes power sequences common for the class of components supported by the
> + * simple component prober:
> + * * @gpio_name is configured to the non-active setting according to @gpio_assert_to_enable.
> + * * @supply_name regulator supply is enabled.
> + * * Wait for @post_power_on_delay_ms to pass.
> + * * @gpio_name is configured to the active setting according to @gpio_assert_to_enable.
> + * * Wait for @post_gpio_config_delay_ms to pass.
>   */
>  struct i2c_of_probe_simple_opts {
>  	const char *res_node_compatible;
>  	const char *supply_name;
> +	const char *gpio_name;
>  	unsigned int post_power_on_delay_ms;
> +	unsigned int post_gpio_config_delay_ms;
> +	bool gpio_assert_to_enable;

This header is missing '#include <linux/types.h>' for bool
type. Otherwise compilation may fail with following error:

```
./include/linux/i2c-of-prober.h:117:9: error: unknown type name ‘bool’
  117 |         bool gpio_assert_to_enable;
      |         ^~~~
./include/linux/i2c-of-prober.h:12:1: note: ‘bool’ is defined in header ‘<stdbool.h>’; this is probably fixable by adding ‘#include <stdbool.h>’
   11 | #include <linux/kconfig.h>
  +++ |+#include <stdbool.h>
   12 |
```

>  };
>  
> +struct gpio_desc;
>  struct regulator;
>  
>  struct i2c_of_probe_simple_ctx {
> @@ -107,9 +125,11 @@ struct i2c_of_probe_simple_ctx {
>  	const struct i2c_of_probe_simple_opts *opts;
>  	/* private: internal fields for helpers. */
>  	struct regulator *supply;
> +	struct gpio_desc *gpiod;
>  };
>  
>  int i2c_of_probe_simple_enable(struct device *dev, struct device_node *bus_node, void *data);
> +void i2c_of_probe_simple_cleanup_early(struct device *dev, void *data);
>  void i2c_of_probe_simple_cleanup(struct device *dev, void *data);
>  
>  extern struct i2c_of_probe_ops i2c_of_probe_simple_ops;
> -- 
> 2.47.0.163.g1226f6d8fa-goog
> 

-- 
Best regards,
Andrey Skvortsov