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// SPDX-License-Identifier: GPL-2.0-only
/*
* sl28cpld watchdog driver
*
* Copyright 2020 Kontron Europe GmbH
*/
#include <linux/kernel.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/regmap.h>
#include <linux/watchdog.h>
/*
* Watchdog timer block registers.
*/
#define WDT_CTRL 0x00
#define WDT_CTRL_EN BIT(0)
#define WDT_CTRL_LOCK BIT(2)
#define WDT_CTRL_ASSERT_SYS_RESET BIT(6)
#define WDT_CTRL_ASSERT_WDT_TIMEOUT BIT(7)
#define WDT_TIMEOUT 0x01
#define WDT_KICK 0x02
#define WDT_KICK_VALUE 0x6b
#define WDT_COUNT 0x03
#define WDT_DEFAULT_TIMEOUT 10
static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
static int timeout;
module_param(timeout, int, 0);
MODULE_PARM_DESC(timeout, "Initial watchdog timeout in seconds");
struct sl28cpld_wdt {
struct watchdog_device wdd;
struct regmap *regmap;
u32 offset;
bool assert_wdt_timeout;
};
static int sl28cpld_wdt_ping(struct watchdog_device *wdd)
{
struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);
return regmap_write(wdt->regmap, wdt->offset + WDT_KICK,
WDT_KICK_VALUE);
}
static int sl28cpld_wdt_start(struct watchdog_device *wdd)
{
struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);
unsigned int val;
val = WDT_CTRL_EN | WDT_CTRL_ASSERT_SYS_RESET;
if (wdt->assert_wdt_timeout)
val |= WDT_CTRL_ASSERT_WDT_TIMEOUT;
if (nowayout)
val |= WDT_CTRL_LOCK;
return regmap_update_bits(wdt->regmap, wdt->offset + WDT_CTRL,
val, val);
}
static int sl28cpld_wdt_stop(struct watchdog_device *wdd)
{
struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);
return regmap_update_bits(wdt->regmap, wdt->offset + WDT_CTRL,
WDT_CTRL_EN, 0);
}
static unsigned int sl28cpld_wdt_get_timeleft(struct watchdog_device *wdd)
{
struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);
unsigned int val;
int ret;
ret = regmap_read(wdt->regmap, wdt->offset + WDT_COUNT, &val);
if (ret)
return 0;
return val;
}
static int sl28cpld_wdt_set_timeout(struct watchdog_device *wdd,
unsigned int timeout)
{
struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);
int ret;
ret = regmap_write(wdt->regmap, wdt->offset + WDT_TIMEOUT, timeout);
if (ret)
return ret;
wdd->timeout = timeout;
return 0;
}
static const struct watchdog_info sl28cpld_wdt_info = {
.options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
.identity = "sl28cpld watchdog",
};
static struct watchdog_ops sl28cpld_wdt_ops = {
.owner = THIS_MODULE,
.start = sl28cpld_wdt_start,
.stop = sl28cpld_wdt_stop,
.ping = sl28cpld_wdt_ping,
.set_timeout = sl28cpld_wdt_set_timeout,
.get_timeleft = sl28cpld_wdt_get_timeleft,
};
static int sl28cpld_wdt_probe(struct platform_device *pdev)
{
struct watchdog_device *wdd;
struct sl28cpld_wdt *wdt;
unsigned int status;
unsigned int val;
int ret;
if (!pdev->dev.parent)
return -ENODEV;
wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
if (!wdt)
return -ENOMEM;
wdt->regmap = dev_get_regmap(pdev->dev.parent, NULL);
if (!wdt->regmap)
return -ENODEV;
ret = device_property_read_u32(&pdev->dev, "reg", &wdt->offset);
if (ret)
return -EINVAL;
wdt->assert_wdt_timeout = device_property_read_bool(&pdev->dev,
"kontron,assert-wdt-timeout-pin");
/* initialize struct watchdog_device */
wdd = &wdt->wdd;
wdd->parent = &pdev->dev;
wdd->info = &sl28cpld_wdt_info;
wdd->ops = &sl28cpld_wdt_ops;
wdd->min_timeout = 1;
wdd->max_timeout = 255;
watchdog_set_drvdata(wdd, wdt);
watchdog_stop_on_reboot(wdd);
/*
* Read the status early, in case of an error, we haven't modified the
* hardware.
*/
ret = regmap_read(wdt->regmap, wdt->offset + WDT_CTRL, &status);
if (ret)
return ret;
/*
* Initial timeout value, may be overwritten by device tree or module
* parameter in watchdog_init_timeout().
*
* Reading a zero here means that either the hardware has a default
* value of zero (which is very unlikely and definitely a hardware
* bug) or the bootloader set it to zero. In any case, we handle
* this case gracefully and set out own timeout.
*/
ret = regmap_read(wdt->regmap, wdt->offset + WDT_TIMEOUT, &val);
if (ret)
return ret;
if (val)
wdd->timeout = val;
else
wdd->timeout = WDT_DEFAULT_TIMEOUT;
watchdog_init_timeout(wdd, timeout, &pdev->dev);
sl28cpld_wdt_set_timeout(wdd, wdd->timeout);
/* if the watchdog is locked, we set nowayout */
if (status & WDT_CTRL_LOCK)
nowayout = true;
watchdog_set_nowayout(wdd, nowayout);
/*
* If watchdog is already running, keep it enabled, but make
* sure its mode is set correctly.
*/
if (status & WDT_CTRL_EN) {
sl28cpld_wdt_start(wdd);
set_bit(WDOG_HW_RUNNING, &wdd->status);
}
ret = devm_watchdog_register_device(&pdev->dev, wdd);
if (ret < 0) {
dev_err(&pdev->dev, "failed to register watchdog device\n");
return ret;
}
dev_info(&pdev->dev, "initial timeout %d sec%s\n",
wdd->timeout, nowayout ? ", nowayout" : "");
return 0;
}
static const struct of_device_id sl28cpld_wdt_of_match[] = {
{ .compatible = "kontron,sl28cpld-wdt" },
{}
};
MODULE_DEVICE_TABLE(of, sl28cpld_wdt_of_match);
static struct platform_driver sl28cpld_wdt_driver = {
.probe = sl28cpld_wdt_probe,
.driver = {
.name = "sl28cpld-wdt",
.of_match_table = sl28cpld_wdt_of_match,
},
};
module_platform_driver(sl28cpld_wdt_driver);
MODULE_DESCRIPTION("sl28cpld Watchdog Driver");
MODULE_AUTHOR("Michael Walle <michael@walle.cc>");
MODULE_LICENSE("GPL");
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