Initial import

1 files changed, 325 insertions, 0 deletions

diff --git a/drivers/power/reset/ltc2952-poweroff.c b/drivers/power/reset/ltc2952-poweroff.c
new file mode 100644
index 000000000..1e0819555
--- /dev/null
+++ b/drivers/power/reset/ltc2952-poweroff.c
@@ -0,0 +1,325 @@
+/*
+ * LTC2952 (PowerPath) driver
+ *
+ * Copyright (C) 2014, Xsens Technologies BV <info@xsens.com>
+ * Maintainer: René Moll <linux@r-moll.nl>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * ----------------------------------------
+ * - Description
+ * ----------------------------------------
+ *
+ * This driver is to be used with an external PowerPath Controller (LTC2952).
+ * Its function is to determine when a external shut down is triggered
+ * and react by properly shutting down the system.
+ *
+ * This driver expects a device tree with a ltc2952 entry for pin mapping.
+ *
+ * ----------------------------------------
+ * - GPIO
+ * ----------------------------------------
+ *
+ * The following GPIOs are used:
+ * - trigger (input)
+ *     A level change indicates the shut-down trigger. If it's state reverts
+ *     within the time-out defined by trigger_delay, the shut down is not
+ *     executed. If no pin is assigned to this input, the driver will start the
+ *     watchdog toggle immediately. The chip will only power off the system if
+ *     it is requested to do so through the kill line.
+ *
+ * - watchdog (output)
+ *     Once a shut down is triggered, the driver will toggle this signal,
+ *     with an internal (wde_interval) to stall the hardware shut down.
+ *
+ * - kill (output)
+ *     The last action during shut down is triggering this signalling, such
+ *     that the PowerPath Control will power down the hardware.
+ *
+ * ----------------------------------------
+ * - Interrupts
+ * ----------------------------------------
+ *
+ * The driver requires a non-shared, edge-triggered interrupt on the trigger
+ * GPIO.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/device.h>
+#include <linux/platform_device.h>
+#include <linux/ktime.h>
+#include <linux/slab.h>
+#include <linux/kmod.h>
+#include <linux/module.h>
+#include <linux/gpio/consumer.h>
+#include <linux/reboot.h>
+
+struct ltc2952_poweroff {
+	struct hrtimer timer_trigger;
+	struct hrtimer timer_wde;
+
+	ktime_t trigger_delay;
+	ktime_t wde_interval;
+
+	struct device *dev;
+
+	struct gpio_desc *gpio_trigger;
+	struct gpio_desc *gpio_watchdog;
+	struct gpio_desc *gpio_kill;
+
+	bool kernel_panic;
+	struct notifier_block panic_notifier;
+};
+
+#define to_ltc2952(p, m) container_of(p, struct ltc2952_poweroff, m)
+
+/*
+ * This global variable is only needed for pm_power_off. We should
+ * remove it entirely once we don't need the global state anymore.
+ */
+static struct ltc2952_poweroff *ltc2952_data;
+
+/**
+ * ltc2952_poweroff_timer_wde - Timer callback
+ * Toggles the watchdog reset signal each wde_interval
+ *
+ * @timer: corresponding timer
+ *
+ * Returns HRTIMER_RESTART for an infinite loop which will only stop when the
+ * machine actually shuts down
+ */
+static enum hrtimer_restart ltc2952_poweroff_timer_wde(struct hrtimer *timer)
+{
+	ktime_t now;
+	int state;
+	unsigned long overruns;
+	struct ltc2952_poweroff *data = to_ltc2952(timer, timer_wde);
+
+	if (data->kernel_panic)
+		return HRTIMER_NORESTART;
+
+	state = gpiod_get_value(data->gpio_watchdog);
+	gpiod_set_value(data->gpio_watchdog, !state);
+
+	now = hrtimer_cb_get_time(timer);
+	overruns = hrtimer_forward(timer, now, data->wde_interval);
+
+	return HRTIMER_RESTART;
+}
+
+static void ltc2952_poweroff_start_wde(struct ltc2952_poweroff *data)
+{
+	hrtimer_start(&data->timer_wde, data->wde_interval, HRTIMER_MODE_REL);
+}
+
+static enum hrtimer_restart
+ltc2952_poweroff_timer_trigger(struct hrtimer *timer)
+{
+	struct ltc2952_poweroff *data = to_ltc2952(timer, timer_trigger);
+
+	ltc2952_poweroff_start_wde(data);
+	dev_info(data->dev, "executing shutdown\n");
+	orderly_poweroff(true);
+
+	return HRTIMER_NORESTART;
+}
+
+/**
+ * ltc2952_poweroff_handler - Interrupt handler
+ * Triggered each time the trigger signal changes state and (de)activates a
+ * time-out (timer_trigger). Once the time-out is actually reached the shut
+ * down is executed.
+ *
+ * @irq: IRQ number
+ * @dev_id: pointer to the main data structure
+ */
+static irqreturn_t ltc2952_poweroff_handler(int irq, void *dev_id)
+{
+	struct ltc2952_poweroff *data = dev_id;
+
+	if (data->kernel_panic || hrtimer_active(&data->timer_wde)) {
+		/* shutdown is already triggered, nothing to do any more */
+		return IRQ_HANDLED;
+	}
+
+	if (gpiod_get_value(data->gpio_trigger)) {
+		hrtimer_start(&data->timer_trigger, data->trigger_delay,
+			      HRTIMER_MODE_REL);
+	} else {
+		hrtimer_cancel(&data->timer_trigger);
+		/* omitting return value check, timer should have been valid */
+	}
+	return IRQ_HANDLED;
+}
+
+static void ltc2952_poweroff_kill(void)
+{
+	gpiod_set_value(ltc2952_data->gpio_kill, 1);
+}
+
+static void ltc2952_poweroff_default(struct ltc2952_poweroff *data)
+{
+	data->wde_interval = ktime_set(0, 300L*1E6L);
+	data->trigger_delay = ktime_set(2, 500L*1E6L);
+
+	hrtimer_init(&data->timer_trigger, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+	data->timer_trigger.function = ltc2952_poweroff_timer_trigger;
+
+	hrtimer_init(&data->timer_wde, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+	data->timer_wde.function = ltc2952_poweroff_timer_wde;
+}
+
+static int ltc2952_poweroff_init(struct platform_device *pdev)
+{
+	int ret;
+	struct ltc2952_poweroff *data = platform_get_drvdata(pdev);
+
+	ltc2952_poweroff_default(data);
+
+	data->gpio_watchdog = devm_gpiod_get(&pdev->dev, "watchdog",
+					     GPIOD_OUT_LOW);
+	if (IS_ERR(data->gpio_watchdog)) {
+		ret = PTR_ERR(data->gpio_watchdog);
+		dev_err(&pdev->dev, "unable to claim gpio \"watchdog\"\n");
+		return ret;
+	}
+
+	data->gpio_kill = devm_gpiod_get(&pdev->dev, "kill", GPIOD_OUT_LOW);
+	if (IS_ERR(data->gpio_kill)) {
+		ret = PTR_ERR(data->gpio_kill);
+		dev_err(&pdev->dev, "unable to claim gpio \"kill\"\n");
+		return ret;
+	}
+
+	data->gpio_trigger = devm_gpiod_get(&pdev->dev, "trigger", GPIOD_IN);
+	if (IS_ERR(data->gpio_trigger)) {
+		/*
+		 * It's not a problem if the trigger gpio isn't available, but
+		 * it is worth a warning if its use was defined in the device
+		 * tree.
+		 */
+		if (PTR_ERR(data->gpio_trigger) != -ENOENT)
+			dev_err(&pdev->dev,
+				"unable to claim gpio \"trigger\"\n");
+		data->gpio_trigger = NULL;
+	}
+
+	if (devm_request_irq(&pdev->dev, gpiod_to_irq(data->gpio_trigger),
+			     ltc2952_poweroff_handler,
+			     (IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING),
+			     "ltc2952-poweroff",
+			     data)) {
+		/*
+		 * Some things may have happened:
+		 * - No trigger input was defined
+		 * - Claiming the GPIO failed
+		 * - We could not map to an IRQ
+		 * - We couldn't register an interrupt handler
+		 *
+		 * None of these really are problems, but all of them
+		 * disqualify the push button from controlling the power.
+		 *
+		 * It is therefore important to note that if the ltc2952
+		 * detects a button press for long enough, it will still start
+		 * its own powerdown window and cut the power on us if we don't
+		 * start the watchdog trigger.
+		 */
+		if (data->gpio_trigger) {
+			dev_warn(&pdev->dev,
+				 "unable to configure the trigger interrupt\n");
+			devm_gpiod_put(&pdev->dev, data->gpio_trigger);
+			data->gpio_trigger = NULL;
+		}
+		dev_info(&pdev->dev,
+			 "power down trigger input will not be used\n");
+		ltc2952_poweroff_start_wde(data);
+	}
+
+	return 0;
+}
+
+static int ltc2952_poweroff_notify_panic(struct notifier_block *nb,
+					 unsigned long code, void *unused)
+{
+	struct ltc2952_poweroff *data = to_ltc2952(nb, panic_notifier);
+
+	data->kernel_panic = true;
+	return NOTIFY_DONE;
+}
+
+static int ltc2952_poweroff_probe(struct platform_device *pdev)
+{
+	int ret;
+	struct ltc2952_poweroff *data;
+
+	if (pm_power_off) {
+		dev_err(&pdev->dev, "pm_power_off already registered");
+		return -EBUSY;
+	}
+
+	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->dev = &pdev->dev;
+	platform_set_drvdata(pdev, data);
+
+	ret = ltc2952_poweroff_init(pdev);
+	if (ret)
+		return ret;
+
+	/* TODO: remove ltc2952_data */
+	ltc2952_data = data;
+	pm_power_off = ltc2952_poweroff_kill;
+
+	data->panic_notifier.notifier_call = ltc2952_poweroff_notify_panic;
+	atomic_notifier_chain_register(&panic_notifier_list,
+				       &data->panic_notifier);
+	dev_info(&pdev->dev, "probe successful\n");
+
+	return 0;
+}
+
+static int ltc2952_poweroff_remove(struct platform_device *pdev)
+{
+	struct ltc2952_poweroff *data = platform_get_drvdata(pdev);
+
+	pm_power_off = NULL;
+	hrtimer_cancel(&data->timer_trigger);
+	hrtimer_cancel(&data->timer_wde);
+	atomic_notifier_chain_unregister(&panic_notifier_list,
+					 &data->panic_notifier);
+	return 0;
+}
+
+static const struct of_device_id of_ltc2952_poweroff_match[] = {
+	{ .compatible = "lltc,ltc2952"},
+	{},
+};
+MODULE_DEVICE_TABLE(of, of_ltc2952_poweroff_match);
+
+static struct platform_driver ltc2952_poweroff_driver = {
+	.probe = ltc2952_poweroff_probe,
+	.remove = ltc2952_poweroff_remove,
+	.driver = {
+		.name = "ltc2952-poweroff",
+		.of_match_table = of_ltc2952_poweroff_match,
+	},
+};
+
+module_platform_driver(ltc2952_poweroff_driver);
+
+MODULE_AUTHOR("René Moll <rene.moll@xsens.com>");
+MODULE_DESCRIPTION("LTC PowerPath power-off driver");
+MODULE_LICENSE("GPL v2");