/*
 * Copyright © 2014 Broadcom Corporation
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * 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.
 */

#define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/stat.h>
#include <linux/device.h>
#include <linux/platform_device.h>
#include <linux/suspend.h>
#include <linux/err.h>
#include <linux/of.h>
#include <linux/pm.h>
#include <linux/io.h>
#include <linux/interrupt.h>
#include <linux/irqreturn.h>
#include <linux/pm_wakeup.h>
#include <linux/reboot.h>

#define DRV_NAME	"brcm-waketimer"

struct brcmstb_waketmr {
	struct device *dev;
	void __iomem *base;
	unsigned int irq;

	int wake_timeout;
	struct notifier_block reboot_notifier;
};

/* No timeout */
#define BRCMSTB_WKTMR_DEFAULT_TIMEOUT	(-1)

#define BRCMSTB_WKTMR_EVENT		0x00
#define BRCMSTB_WKTMR_COUNTER		0x04
#define BRCMSTB_WKTMR_ALARM		0x08
#define BRCMSTB_WKTMR_PRESCALER		0x0C
#define BRCMSTB_WKTMR_PRESACALER_VAL	0x10

static inline void brcmstb_waketmr_clear_alarm(struct brcmstb_waketmr *timer)
{
	writel_relaxed(1, timer->base + BRCMSTB_WKTMR_EVENT);
	(void)readl_relaxed(timer->base + BRCMSTB_WKTMR_EVENT);
}

static void brcmstb_waketmr_set_alarm(struct brcmstb_waketmr *timer,
		unsigned int secs)
{
	unsigned int t;

	brcmstb_waketmr_clear_alarm(timer);

	t = readl_relaxed(timer->base + BRCMSTB_WKTMR_COUNTER);
	writel_relaxed(t + secs + 1, timer->base + BRCMSTB_WKTMR_ALARM);
}

static irqreturn_t brcmstb_waketmr_irq(int irq, void *data)
{
	struct brcmstb_waketmr *timer = data;
	pm_wakeup_event(timer->dev, 0);
	return IRQ_HANDLED;
}

static ssize_t brcmstb_waketmr_timeout_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct brcmstb_waketmr *timer = dev_get_drvdata(dev);

	return snprintf(buf, PAGE_SIZE, "%d\n", timer->wake_timeout);
}

static ssize_t brcmstb_waketmr_timeout_store(struct device *dev,
		struct device_attribute *attr, const char *buf, size_t count)
{
	struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
	int timeout;
	int ret;

	ret = kstrtoint(buf, 0, &timeout);
	if (ret < 0)
		return ret;

	/* Allow -1 as "no timeout" */
	if (timeout < -1)
		return -EINVAL;

	timer->wake_timeout = timeout;

	return count;
}

static const DEVICE_ATTR(timeout, S_IRUGO | S_IWUSR,
		brcmstb_waketmr_timeout_show,
		brcmstb_waketmr_timeout_store);

static int brcmstb_waketmr_prepare_suspend(struct brcmstb_waketmr *timer)
{
	struct device *dev = timer->dev;
	int ret;

	if (device_may_wakeup(dev) && timer->wake_timeout >= 0) {
		ret = enable_irq_wake(timer->irq);
		if (ret) {
			dev_err(dev, "failed to enable wake-up interrupt\n");
			return ret;
		}

		brcmstb_waketmr_set_alarm(timer, timer->wake_timeout);
	}
	return 0;
}

/* If enabled as a wakeup-source, arm the timer when powering off */
static int brcmstb_waketmr_reboot(struct notifier_block *nb,
		unsigned long action, void *data)
{
	struct brcmstb_waketmr *timer;
	timer = container_of(nb, struct brcmstb_waketmr, reboot_notifier);

	/* Set timer for cold boot */
	if (action == SYS_POWER_OFF)
		brcmstb_waketmr_prepare_suspend(timer);

	return NOTIFY_DONE;
}

static int brcmstb_waketmr_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct brcmstb_waketmr *timer;
	struct resource *res;
	int ret;

	timer = devm_kzalloc(dev, sizeof(*timer), GFP_KERNEL);
	if (!timer)
		return -ENOMEM;
	platform_set_drvdata(pdev, timer);

	timer->dev = dev;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	timer->base = devm_ioremap_resource(dev, res);
	if (IS_ERR(timer->base))
		return PTR_ERR(timer->base);

	/*
	 * Set wakeup capability before requesting wakeup interrupt, so we can
	 * process boot-time "wakeups" (e.g., from S5 soft-off)
	 */
	device_set_wakeup_capable(dev, true);
	device_wakeup_enable(dev);

	timer->irq = platform_get_irq(pdev, 0);
	if ((int)timer->irq < 0)
		return -ENODEV;

	ret = devm_request_irq(dev, timer->irq, brcmstb_waketmr_irq, 0,
			                DRV_NAME, timer);
	if (ret < 0)
		return ret;

	timer->reboot_notifier.notifier_call = brcmstb_waketmr_reboot;
	register_reboot_notifier(&timer->reboot_notifier);

	timer->wake_timeout = BRCMSTB_WKTMR_DEFAULT_TIMEOUT;

	ret = device_create_file(dev, &dev_attr_timeout);
	if (ret)
		unregister_reboot_notifier(&timer->reboot_notifier);
	else
		dev_info(dev, "registered, with irq %d\n", timer->irq);
	return ret;
}

static int brcmstb_waketmr_remove(struct platform_device *pdev)
{
	struct brcmstb_waketmr *timer = dev_get_drvdata(&pdev->dev);

	device_remove_file(&pdev->dev, &dev_attr_timeout);
	unregister_reboot_notifier(&timer->reboot_notifier);

	return 0;
}

#ifdef CONFIG_PM_SLEEP
static int brcmstb_waketmr_suspend(struct device *dev)
{
	struct brcmstb_waketmr *timer = dev_get_drvdata(dev);

	return brcmstb_waketmr_prepare_suspend(timer);
}

static int brcmstb_waketmr_resume(struct device *dev)
{
	struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
	int ret;

	if (!device_may_wakeup(dev) || timer->wake_timeout < 0)
		return 0;

	ret = disable_irq_wake(timer->irq);

	brcmstb_waketmr_clear_alarm(timer);

	return ret;
}
#endif /* CONFIG_PM_SLEEP */

static SIMPLE_DEV_PM_OPS(brcmstb_waketmr_pm_ops, brcmstb_waketmr_suspend,
		brcmstb_waketmr_resume);

static const struct of_device_id brcmstb_waketmr_of_match[] = {
	{ .compatible = "brcm,brcmstb-waketimer" },
	{},
};

static struct platform_driver brcmstb_waketmr_driver = {
	.probe			= brcmstb_waketmr_probe,
	.remove			= brcmstb_waketmr_remove,
	.driver = {
		.name		= DRV_NAME,
		.owner		= THIS_MODULE,
		.pm		= &brcmstb_waketmr_pm_ops,
		.of_match_table	= of_match_ptr(brcmstb_waketmr_of_match),
	}
};
module_platform_driver(brcmstb_waketmr_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Broadcom Corporation");
MODULE_DESCRIPTION("Wake-up timer driver for STB chips");