linux-kernel - [PATCH 2/2] HID: i2c-hid: Add the ability to control a reset GPIO

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Message-Id: <20201014164203.2.Ied4ce10d229cd7c69abf13a0361ba0b8d82eb9c4@changeid>
Date:   Wed, 14 Oct 2020 16:42:21 -0700
From:   Douglas Anderson <dianders@...omium.org>
To:     jkosina@...e.cz, benjamin.tissoires@...hat.com,
        gregkh@...uxfoundation.org
Cc:     kai.heng.feng@...onical.com, linux-input@...r.kernel.org,
        hdegoede@...hat.com, andrea@...gia.bo.it, swboyd@...omium.org,
        Douglas Anderson <dianders@...omium.org>,
        Aaron Ma <aaron.ma@...onical.com>,
        Jiri Kosina <jikos@...nel.org>, Pavel Balan <admin@...ma.net>,
        You-Sheng Yang <vicamo.yang@...onical.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] HID: i2c-hid: Add the ability to control a reset GPIO

Apparently some devices connected via i2c-hid have timing requirements
around when a reset GPIO should be asserted to them.  The diagram I
have seen, which I believe is from a Goodix device, looked like this:

         +----------------------------------
         |
AVDD ----+
               +------------------------------
         | (a) |
RESET ---------+
                     +-------------
               | (b) |
I2C comm OK ---------+

Where (a) is 10 ms and (b) is 120 ms.

Let's add the ability to support this into the i2c-hid driver.

Signed-off-by: Douglas Anderson <dianders@...omium.org>
---

 drivers/hid/i2c-hid/i2c-hid-core.c    | 18 ++++++++++++++++++
 include/linux/platform_data/i2c-hid.h |  5 +++++
 2 files changed, 23 insertions(+)

diff --git a/drivers/hid/i2c-hid/i2c-hid-core.c b/drivers/hid/i2c-hid/i2c-hid-core.c
index 786e3e9af1c9..807b344b697b 100644
--- a/drivers/hid/i2c-hid/i2c-hid-core.c
+++ b/drivers/hid/i2c-hid/i2c-hid-core.c
@@ -1005,6 +1005,9 @@ static void i2c_hid_fwnode_probe(struct i2c_client *client,
 	if (!device_property_read_u32(&client->dev, "post-power-on-delay-ms",
 				      &val))
 		pdata->post_power_delay_ms = val;
+	if (!device_property_read_u32(&client->dev, "post-gpio-reset-delay-ms",
+				      &val))
+		pdata->post_gpio_reset_delay_ms = val;
 }
 
 static int i2c_hid_probe(struct i2c_client *client,
@@ -1053,6 +1056,12 @@ static int i2c_hid_probe(struct i2c_client *client,
 	ihid->pdata.supplies[0].supply = "vdd";
 	ihid->pdata.supplies[1].supply = "vddl";
 
+	/* Start out with reset asserted */
+	ihid->pdata.reset_gpio =
+		devm_gpiod_get_optional(&client->dev, "reset", GPIOD_OUT_HIGH);
+	if (IS_ERR(ihid->pdata.reset_gpio))
+		return PTR_ERR(ihid->pdata.reset_gpio);
+
 	ret = devm_regulator_bulk_get(&client->dev,
 				      ARRAY_SIZE(ihid->pdata.supplies),
 				      ihid->pdata.supplies);
@@ -1067,6 +1076,10 @@ static int i2c_hid_probe(struct i2c_client *client,
 	if (ihid->pdata.post_power_delay_ms)
 		msleep(ihid->pdata.post_power_delay_ms);
 
+	gpiod_set_value_cansleep(ihid->pdata.reset_gpio, 0);
+	if (ihid->pdata.post_gpio_reset_delay_ms)
+		msleep(ihid->pdata.post_gpio_reset_delay_ms);
+
 	i2c_set_clientdata(client, ihid);
 
 	ihid->client = client;
@@ -1163,6 +1176,7 @@ static int i2c_hid_remove(struct i2c_client *client)
 	if (ihid->bufsize)
 		i2c_hid_free_buffers(ihid);
 
+	gpiod_set_value_cansleep(ihid->pdata.reset_gpio, 1);
 	regulator_bulk_disable(ARRAY_SIZE(ihid->pdata.supplies),
 			       ihid->pdata.supplies);
 
@@ -1228,6 +1242,10 @@ static int i2c_hid_resume(struct device *dev)
 
 		if (ihid->pdata.post_power_delay_ms)
 			msleep(ihid->pdata.post_power_delay_ms);
+
+		gpiod_set_value_cansleep(ihid->pdata.reset_gpio, 0);
+		if (ihid->pdata.post_gpio_reset_delay_ms)
+			msleep(ihid->pdata.post_gpio_reset_delay_ms);
 	} else if (ihid->irq_wake_enabled) {
 		wake_status = disable_irq_wake(client->irq);
 		if (!wake_status)
diff --git a/include/linux/platform_data/i2c-hid.h b/include/linux/platform_data/i2c-hid.h
index c628bb5e1061..b2150223ffa6 100644
--- a/include/linux/platform_data/i2c-hid.h
+++ b/include/linux/platform_data/i2c-hid.h
@@ -12,6 +12,7 @@
 #ifndef __LINUX_I2C_HID_H
 #define __LINUX_I2C_HID_H
 
+#include <linux/gpio/consumer.h>
 #include <linux/regulator/consumer.h>
 #include <linux/types.h>
 
@@ -20,6 +21,8 @@
  * @hid_descriptor_address: i2c register where the HID descriptor is stored.
  * @supplies: regulators for powering on the device.
  * @post_power_delay_ms: delay after powering on before device is usable.
+ * @post_gpio_reset_delay_ms: delay after reset via GPIO.
+ * @reset_gpio: optional gpio to de-assert after post_power_delay_ms.
  *
  * Note that it is the responsibility of the platform driver (or the acpi 5.0
  * driver, or the flattened device tree) to setup the irq related to the gpio in
@@ -36,6 +39,8 @@ struct i2c_hid_platform_data {
 	u16 hid_descriptor_address;
 	struct regulator_bulk_data supplies[2];
 	int post_power_delay_ms;
+	int post_gpio_reset_delay_ms;
+	struct gpio_desc *reset_gpio;
 };
 
 #endif /* __LINUX_I2C_HID_H */
-- 
2.28.0.1011.ga647a8990f-goog