i2c: of-prober: Add simple helpers for regulator support

Add helpers to do regulator management 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.
GPIOs will be handled in the next 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 set of helpers supports at most one regulator supply. The user
must specify the node from which the supply is retrieved. The supply
name and the amount of time to wait after the supply is enabled are
also given by the user.

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>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

1 files changed, 44 insertions, 0 deletions

diff --git a/include/linux/i2c-of-prober.h b/include/linux/i2c-of-prober.h
index e7e052ac9e48..df95aa6ad90e 100644
--- a/include/linux/i2c-of-prober.h
+++ b/include/linux/i2c-of-prober.h
@@ -70,6 +70,50 @@ struct i2c_of_probe_cfg {
 
 int i2c_of_probe_component(struct device *dev, const struct i2c_of_probe_cfg *cfg, void *ctx);
 
+/**
+ * DOC: I2C OF component prober simple helpers
+ *
+ * Components such as trackpads are commonly connected to a devices baseboard
+ * with a 6-pin ribbon cable. That gives at most one voltage supply and one
+ * GPIO (commonly a "enable" or "reset" line) besides the I2C bus, interrupt
+ * pin, and common ground. Touchscreens, while integrated into the display
+ * panel's connection, typically have the same set of connections.
+ *
+ * A simple set of helpers are provided here for use with the I2C OF component
+ * prober. This implementation targets such components, allowing for at most
+ * one regulator supply.
+ *
+ * The following helpers are provided:
+ * * i2c_of_probe_simple_enable()
+ * * i2c_of_probe_simple_cleanup()
+ */
+
+/**
+ * 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.
+ * @post_power_on_delay_ms: Delay after regulators are powered on. Passed to msleep().
+ */
+struct i2c_of_probe_simple_opts {
+	const char *res_node_compatible;
+	const char *supply_name;
+	unsigned int post_power_on_delay_ms;
+};
+
+struct regulator;
+
+struct i2c_of_probe_simple_ctx {
+	/* public: provided by user before helpers are used. */
+	const struct i2c_of_probe_simple_opts *opts;
+	/* private: internal fields for helpers. */
+	struct regulator *supply;
+};
+
+int i2c_of_probe_simple_enable(struct device *dev, struct device_node *bus_node, void *data);
+void i2c_of_probe_simple_cleanup(struct device *dev, void *data);
+
+extern struct i2c_of_probe_ops i2c_of_probe_simple_ops;
+
 #endif /* IS_ENABLED(CONFIG_OF_DYNAMIC) */
 
 #endif /* _LINUX_I2C_OF_PROBER_H */