i2c: of-prober: Add GPIO support to simple helpers

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@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Andrey Skvortsov <andrej.skvortzov@gmail.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

1 files changed, 21 insertions, 0 deletions

diff --git a/include/linux/i2c-of-prober.h b/include/linux/i2c-of-prober.h
index df95aa6ad90e..bb6d47f50ee5 100644
--- a/include/linux/i2c-of-prober.h
+++ b/include/linux/i2c-of-prober.h
@@ -9,6 +9,7 @@
 #define _LINUX_I2C_OF_PROBER_H
 
 #include <linux/kconfig.h>
+#include <linux/types.h>
 
 struct device;
 struct device_node;
@@ -85,6 +86,7 @@ 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 +94,31 @@ 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;
 };
 
+struct gpio_desc;
 struct regulator;
 
 struct i2c_of_probe_simple_ctx {
@@ -107,9 +126,11 @@ 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;