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From: Stefan Eichenberger <eichest@gmail.com>
To: nick@shmanahar.org,
	dmitry.torokhov@gmail.com,
	robh+dt@kernel.org,
	krzysztof.kozlowski+dt@linaro.org,
	conor+dt@kernel.org,
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	francesco.dolcini@toradex.com
Cc: linux-input@vger.kernel.org,
	devicetree@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	Stefan Eichenberger <stefan.eichenberger@toradex.com>
Subject: [PATCH v2 2/2] Input: atmel_mxt_ts - support poweroff in suspend
Date: Fri, 22 Dec 2023 10:52:58 +0100
Message-Id: <20231222095258.33369-3-eichest@gmail.com>
In-Reply-To: <20231222095258.33369-1-eichest@gmail.com>
References: <20231222095258.33369-1-eichest@gmail.com>
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From: Stefan Eichenberger <stefan.eichenberger@toradex.com>

Add a new device tree property to indicate that the device should be
powered off in suspend mode. We have a shared regulator that powers the
display, a USB hub and some other peripherals. The maXTouch controller
doesn't normally disable the regulator in suspend mode, so our extra
peripherals stay powered on. This is not desirable as it consumes more
power. With this patch we add the option to disable the regulator in
suspend mode for the maXTouch and accept the longer initialisation time.

Signed-off-by: Stefan Eichenberger <stefan.eichenberger@toradex.com>
---
 drivers/input/touchscreen/atmel_mxt_ts.c | 72 ++++++++++++++++++------
 1 file changed, 55 insertions(+), 17 deletions(-)

diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
index 20094b9899f0..3f7f58f1c930 100644
--- a/drivers/input/touchscreen/atmel_mxt_ts.c
+++ b/drivers/input/touchscreen/atmel_mxt_ts.c
@@ -317,6 +317,7 @@ struct mxt_data {
 	struct gpio_desc *reset_gpio;
 	struct gpio_desc *wake_gpio;
 	bool use_retrigen_workaround;
+	bool poweroff_sleep;
 
 	/* Cached parameters from object table */
 	u16 T5_address;
@@ -2799,15 +2800,18 @@ static int mxt_configure_objects(struct mxt_data *data,
 			dev_warn(dev, "Error %d updating config\n", error);
 	}
 
-	if (data->multitouch) {
-		error = mxt_initialize_input_device(data);
-		if (error)
-			return error;
-	} else {
-		dev_warn(dev, "No touch object detected\n");
-	}
+	/* If input device is not already registered */
+	if (!data->input_dev) {
+		if (data->multitouch) {
+			error = mxt_initialize_input_device(data);
+			if (error)
+				return error;
+		} else {
+			dev_warn(dev, "No touch object detected\n");
+		}
 
-	mxt_debug_init(data);
+		mxt_debug_init(data);
+	}
 
 	return 0;
 }
@@ -3328,6 +3332,8 @@ static int mxt_probe(struct i2c_client *client)
 		msleep(MXT_RESET_INVALID_CHG);
 	}
 
+	data->poweroff_sleep = device_property_read_bool(&client->dev,
+							 "atmel,poweroff-sleep");
 	/*
 	 * Controllers like mXT1386 have a dedicated WAKE line that could be
 	 * connected to a GPIO or to I2C SCL pin, or permanently asserted low.
@@ -3390,12 +3396,21 @@ static int mxt_suspend(struct device *dev)
 	if (!input_dev)
 		return 0;
 
-	mutex_lock(&input_dev->mutex);
+	if (!device_may_wakeup(dev) && data->poweroff_sleep) {
+		if (data->reset_gpio)
+			gpiod_set_value(data->reset_gpio, 1);
 
-	if (input_device_enabled(input_dev))
-		mxt_stop(data);
+		regulator_bulk_disable(ARRAY_SIZE(data->regulators),
+				data->regulators);
+		data->T44_address = 0;
+	} else {
+		mutex_lock(&input_dev->mutex);
+
+		if (input_device_enabled(input_dev))
+			mxt_stop(data);
 
-	mutex_unlock(&input_dev->mutex);
+		mutex_unlock(&input_dev->mutex);
+	}
 
 	disable_irq(data->irq);
 
@@ -3411,14 +3426,37 @@ static int mxt_resume(struct device *dev)
 	if (!input_dev)
 		return 0;
 
-	enable_irq(data->irq);
+	if (!device_may_wakeup(dev) && data->poweroff_sleep) {
+		int ret;
 
-	mutex_lock(&input_dev->mutex);
+		ret = regulator_bulk_enable(ARRAY_SIZE(data->regulators),
+				data->regulators);
+		if (ret) {
+			dev_err(dev, "failed to enable regulators: %d\n",
+					ret);
+			return ret;
+		}
+		msleep(MXT_BACKUP_TIME);
 
-	if (input_device_enabled(input_dev))
-		mxt_start(data);
+		if (data->reset_gpio) {
+			/* Wait a while and then de-assert the RESET GPIO line */
+			msleep(MXT_RESET_GPIO_TIME);
+			gpiod_set_value(data->reset_gpio, 0);
+			msleep(MXT_RESET_INVALID_CHG);
+		}
 
-	mutex_unlock(&input_dev->mutex);
+		/* This also enables the irq again */
+		mxt_initialize(data);
+	} else {
+		enable_irq(data->irq);
+
+		mutex_lock(&input_dev->mutex);
+
+		if (input_device_enabled(input_dev))
+			mxt_start(data);
+
+		mutex_unlock(&input_dev->mutex);
+	}
 
 	return 0;
 }
-- 
2.40.1