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path: root/drivers/power/reset/gpio-poweroff.c
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-rw-r--r--drivers/power/reset/gpio-poweroff.c109
1 files changed, 109 insertions, 0 deletions
diff --git a/drivers/power/reset/gpio-poweroff.c b/drivers/power/reset/gpio-poweroff.c
new file mode 100644
index 000000000..1c5af2fef
--- /dev/null
+++ b/drivers/power/reset/gpio-poweroff.c
@@ -0,0 +1,109 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Toggles a GPIO pin to power down a device
+ *
+ * Jamie Lentin <jm@lentin.co.uk>
+ * Andrew Lunn <andrew@lunn.ch>
+ *
+ * Copyright (C) 2012 Jamie Lentin
+ */
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/platform_device.h>
+#include <linux/gpio/consumer.h>
+#include <linux/of_platform.h>
+#include <linux/module.h>
+
+#define DEFAULT_TIMEOUT_MS 3000
+/*
+ * Hold configuration here, cannot be more than one instance of the driver
+ * since pm_power_off itself is global.
+ */
+static struct gpio_desc *reset_gpio;
+static u32 timeout = DEFAULT_TIMEOUT_MS;
+static u32 active_delay = 100;
+static u32 inactive_delay = 100;
+
+static void gpio_poweroff_do_poweroff(void)
+{
+ BUG_ON(!reset_gpio);
+
+ /* drive it active, also inactive->active edge */
+ gpiod_direction_output(reset_gpio, 1);
+ mdelay(active_delay);
+
+ /* drive inactive, also active->inactive edge */
+ gpiod_set_value_cansleep(reset_gpio, 0);
+ mdelay(inactive_delay);
+
+ /* drive it active, also inactive->active edge */
+ gpiod_set_value_cansleep(reset_gpio, 1);
+
+ /* give it some time */
+ mdelay(timeout);
+
+ WARN_ON(1);
+}
+
+static int gpio_poweroff_probe(struct platform_device *pdev)
+{
+ bool input = false;
+ enum gpiod_flags flags;
+
+ /* If a pm_power_off function has already been added, leave it alone */
+ if (pm_power_off != NULL) {
+ dev_err(&pdev->dev,
+ "%s: pm_power_off function already registered\n",
+ __func__);
+ return -EBUSY;
+ }
+
+ input = device_property_read_bool(&pdev->dev, "input");
+ if (input)
+ flags = GPIOD_IN;
+ else
+ flags = GPIOD_OUT_LOW;
+
+ device_property_read_u32(&pdev->dev, "active-delay-ms", &active_delay);
+ device_property_read_u32(&pdev->dev, "inactive-delay-ms",
+ &inactive_delay);
+ device_property_read_u32(&pdev->dev, "timeout-ms", &timeout);
+
+ reset_gpio = devm_gpiod_get(&pdev->dev, NULL, flags);
+ if (IS_ERR(reset_gpio))
+ return PTR_ERR(reset_gpio);
+
+ pm_power_off = &gpio_poweroff_do_poweroff;
+ return 0;
+}
+
+static int gpio_poweroff_remove(struct platform_device *pdev)
+{
+ if (pm_power_off == &gpio_poweroff_do_poweroff)
+ pm_power_off = NULL;
+
+ return 0;
+}
+
+static const struct of_device_id of_gpio_poweroff_match[] = {
+ { .compatible = "gpio-poweroff", },
+ {},
+};
+MODULE_DEVICE_TABLE(of, of_gpio_poweroff_match);
+
+static struct platform_driver gpio_poweroff_driver = {
+ .probe = gpio_poweroff_probe,
+ .remove = gpio_poweroff_remove,
+ .driver = {
+ .name = "poweroff-gpio",
+ .of_match_table = of_gpio_poweroff_match,
+ },
+};
+
+module_platform_driver(gpio_poweroff_driver);
+
+MODULE_AUTHOR("Jamie Lentin <jm@lentin.co.uk>");
+MODULE_DESCRIPTION("GPIO poweroff driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:poweroff-gpio");