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// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (C) 2015 Broadcom Corporation
*
*/
#include <linux/clk.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/pm.h>
#include <linux/watchdog.h>
#define WDT_START_1 0xff00
#define WDT_START_2 0x00ff
#define WDT_STOP_1 0xee00
#define WDT_STOP_2 0x00ee
#define WDT_TIMEOUT_REG 0x0
#define WDT_CMD_REG 0x4
#define WDT_MIN_TIMEOUT 1 /* seconds */
#define WDT_DEFAULT_TIMEOUT 30 /* seconds */
#define WDT_DEFAULT_RATE 27000000
struct bcm7038_watchdog {
void __iomem *base;
struct watchdog_device wdd;
u32 rate;
struct clk *clk;
};
static bool nowayout = WATCHDOG_NOWAYOUT;
static void bcm7038_wdt_set_timeout_reg(struct watchdog_device *wdog)
{
struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
u32 timeout;
timeout = wdt->rate * wdog->timeout;
writel(timeout, wdt->base + WDT_TIMEOUT_REG);
}
static int bcm7038_wdt_ping(struct watchdog_device *wdog)
{
struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
writel(WDT_START_1, wdt->base + WDT_CMD_REG);
writel(WDT_START_2, wdt->base + WDT_CMD_REG);
return 0;
}
static int bcm7038_wdt_start(struct watchdog_device *wdog)
{
bcm7038_wdt_set_timeout_reg(wdog);
bcm7038_wdt_ping(wdog);
return 0;
}
static int bcm7038_wdt_stop(struct watchdog_device *wdog)
{
struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
writel(WDT_STOP_1, wdt->base + WDT_CMD_REG);
writel(WDT_STOP_2, wdt->base + WDT_CMD_REG);
return 0;
}
static int bcm7038_wdt_set_timeout(struct watchdog_device *wdog,
unsigned int t)
{
/* Can't modify timeout value if watchdog timer is running */
bcm7038_wdt_stop(wdog);
wdog->timeout = t;
bcm7038_wdt_start(wdog);
return 0;
}
static unsigned int bcm7038_wdt_get_timeleft(struct watchdog_device *wdog)
{
struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
u32 time_left;
time_left = readl(wdt->base + WDT_CMD_REG);
return time_left / wdt->rate;
}
static const struct watchdog_info bcm7038_wdt_info = {
.identity = "Broadcom BCM7038 Watchdog Timer",
.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
WDIOF_MAGICCLOSE
};
static const struct watchdog_ops bcm7038_wdt_ops = {
.owner = THIS_MODULE,
.start = bcm7038_wdt_start,
.stop = bcm7038_wdt_stop,
.set_timeout = bcm7038_wdt_set_timeout,
.get_timeleft = bcm7038_wdt_get_timeleft,
};
static void bcm7038_clk_disable_unprepare(void *data)
{
clk_disable_unprepare(data);
}
static int bcm7038_wdt_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct bcm7038_watchdog *wdt;
int err;
wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
if (!wdt)
return -ENOMEM;
platform_set_drvdata(pdev, wdt);
wdt->base = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(wdt->base))
return PTR_ERR(wdt->base);
wdt->clk = devm_clk_get(dev, NULL);
/* If unable to get clock, use default frequency */
if (!IS_ERR(wdt->clk)) {
err = clk_prepare_enable(wdt->clk);
if (err)
return err;
err = devm_add_action_or_reset(dev,
bcm7038_clk_disable_unprepare,
wdt->clk);
if (err)
return err;
wdt->rate = clk_get_rate(wdt->clk);
/* Prevent divide-by-zero exception */
if (!wdt->rate)
wdt->rate = WDT_DEFAULT_RATE;
} else {
wdt->rate = WDT_DEFAULT_RATE;
wdt->clk = NULL;
}
wdt->wdd.info = &bcm7038_wdt_info;
wdt->wdd.ops = &bcm7038_wdt_ops;
wdt->wdd.min_timeout = WDT_MIN_TIMEOUT;
wdt->wdd.timeout = WDT_DEFAULT_TIMEOUT;
wdt->wdd.max_timeout = 0xffffffff / wdt->rate;
wdt->wdd.parent = dev;
watchdog_set_drvdata(&wdt->wdd, wdt);
watchdog_stop_on_reboot(&wdt->wdd);
watchdog_stop_on_unregister(&wdt->wdd);
err = devm_watchdog_register_device(dev, &wdt->wdd);
if (err) {
dev_err(dev, "Failed to register watchdog device\n");
return err;
}
dev_info(dev, "Registered BCM7038 Watchdog\n");
return 0;
}
#ifdef CONFIG_PM_SLEEP
static int bcm7038_wdt_suspend(struct device *dev)
{
struct bcm7038_watchdog *wdt = dev_get_drvdata(dev);
if (watchdog_active(&wdt->wdd))
return bcm7038_wdt_stop(&wdt->wdd);
return 0;
}
static int bcm7038_wdt_resume(struct device *dev)
{
struct bcm7038_watchdog *wdt = dev_get_drvdata(dev);
if (watchdog_active(&wdt->wdd))
return bcm7038_wdt_start(&wdt->wdd);
return 0;
}
#endif
static SIMPLE_DEV_PM_OPS(bcm7038_wdt_pm_ops, bcm7038_wdt_suspend,
bcm7038_wdt_resume);
static const struct of_device_id bcm7038_wdt_match[] = {
{ .compatible = "brcm,bcm7038-wdt" },
{},
};
MODULE_DEVICE_TABLE(of, bcm7038_wdt_match);
static struct platform_driver bcm7038_wdt_driver = {
.probe = bcm7038_wdt_probe,
.driver = {
.name = "bcm7038-wdt",
.of_match_table = bcm7038_wdt_match,
.pm = &bcm7038_wdt_pm_ops,
}
};
module_platform_driver(bcm7038_wdt_driver);
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Driver for Broadcom 7038 SoCs Watchdog");
MODULE_AUTHOR("Justin Chen");
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