linux-kernel - [PATCH 1/1] Input: rmi_i2c: introduce reset GPIO handling

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Message-ID: <20250210050220.634497-2-felix@kaechele.ca>
Date: Mon, 10 Feb 2025 00:02:09 -0500
From: Felix Kaechele <felix@...chele.ca>
To: Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc: Barnabás Czémán <barnabas.czeman@...nlining.org>,
	linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 1/1] Input: rmi_i2c: introduce reset GPIO handling

Implement reset GPIO handling logic for the rmi_i2c driver. This logic
is required for some mobile devices to successfully initialize the touch
controller.

The timings for the assertion of the reset GPIO were derived from the
GPLv2+ licensed synaptics-dsx-v2.1 vendor driver release and research I
conducted into downstream device tree sources. Values of 10ms to 20ms
are commonly found.

Tested-On: Motorola Moto G5 Plus (XT1685 "potter")

Signed-off-by: Felix Kaechele <felix@...chele.ca>
---
 drivers/input/rmi4/rmi_driver.c |  1 -
 drivers/input/rmi4/rmi_driver.h |  2 ++
 drivers/input/rmi4/rmi_i2c.c    | 23 +++++++++++++++++++++++
 3 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/drivers/input/rmi4/rmi_driver.c b/drivers/input/rmi4/rmi_driver.c
index 2168b6cd7167..ff6aed6a11c1 100644
--- a/drivers/input/rmi4/rmi_driver.c
+++ b/drivers/input/rmi4/rmi_driver.c
@@ -30,7 +30,6 @@
 #define RMI4_PAGE_MASK 0xFF00
 
 #define RMI_DEVICE_RESET_CMD	0x01
-#define DEFAULT_RESET_DELAY_MS	100
 
 void rmi_free_function_list(struct rmi_device *rmi_dev)
 {
diff --git a/drivers/input/rmi4/rmi_driver.h b/drivers/input/rmi4/rmi_driver.h
index 3bfe9013043e..e01453bd680f 100644
--- a/drivers/input/rmi4/rmi_driver.h
+++ b/drivers/input/rmi4/rmi_driver.h
@@ -16,6 +16,8 @@
 #define SYNAPTICS_INPUT_DEVICE_NAME "Synaptics RMI4 Touch Sensor"
 #define SYNAPTICS_VENDOR_ID 0x06cb
 
+#define DEFAULT_RESET_DELAY_MS	100
+
 #define GROUP(_attrs) { \
 	.attrs = _attrs,  \
 }
diff --git a/drivers/input/rmi4/rmi_i2c.c b/drivers/input/rmi4/rmi_i2c.c
index 3c0c5fd44702..beff566ca2c8 100644
--- a/drivers/input/rmi4/rmi_i2c.c
+++ b/drivers/input/rmi4/rmi_i2c.c
@@ -4,6 +4,7 @@
  * Copyright (c) 2011 Unixphere
  */
 
+#include <linux/gpio/consumer.h>
 #include <linux/i2c.h>
 #include <linux/rmi.h>
 #include <linux/of.h>
@@ -26,7 +27,9 @@
  * @tx_buf_size: Size of the buffer
  *
  * @supplies: Array of voltage regulators
+ * @reset_gpio: Reference to the reset GPIO
  * @startup_delay: Milliseconds to pause after powering up the regulators
+ * @reset_delay: Milliseconds to pause after resetting the device
  */
 struct rmi_i2c_xport {
 	struct rmi_transport_dev xport;
@@ -39,7 +42,9 @@ struct rmi_i2c_xport {
 	size_t tx_buf_size;
 
 	struct regulator_bulk_data supplies[2];
+	struct gpio_desc *reset_gpio;
 	u32 startup_delay;
+	u32 reset_delay;
 };
 
 #define RMI_PAGE_SELECT_REGISTER 0xff
@@ -227,6 +232,15 @@ static int rmi_i2c_probe(struct i2c_client *client)
 		return -ENODEV;
 	}
 
+	rmi_i2c->reset_gpio = devm_gpiod_get_optional(&client->dev, "reset",
+						      GPIOD_OUT_HIGH);
+	if (IS_ERR(rmi_i2c->reset_gpio)) {
+		error = PTR_ERR(rmi_i2c->reset_gpio);
+		dev_err(&client->dev, "failed to get reset GPIO: %d\n", error);
+		return error;
+	}
+	gpiod_set_consumer_name(rmi_i2c->reset_gpio, "rmi4 reset");
+
 	rmi_i2c->supplies[0].supply = "vdd";
 	rmi_i2c->supplies[1].supply = "vio";
 	error = devm_regulator_bulk_get(&client->dev,
@@ -251,6 +265,15 @@ static int rmi_i2c_probe(struct i2c_client *client)
 
 	msleep(rmi_i2c->startup_delay);
 
+	if (rmi_i2c->reset_gpio) {
+		of_property_read_u32(client->dev.of_node, "syna,reset-delay-ms",
+				     &rmi_i2c->reset_delay);
+		gpiod_set_value_cansleep(rmi_i2c->reset_gpio, 1);
+		usleep_range(10000, 20000);
+		gpiod_set_value_cansleep(rmi_i2c->reset_gpio, 0);
+		msleep(rmi_i2c->reset_delay ?: DEFAULT_RESET_DELAY_MS);
+	}
+
 	rmi_i2c->client = client;
 	mutex_init(&rmi_i2c->page_mutex);
 
-- 
2.48.1