diff options
Diffstat (limited to 'drivers/watchdog/sl28cpld_wdt.c')
| -rw-r--r-- | drivers/watchdog/sl28cpld_wdt.c | 229 |
1 files changed, 229 insertions, 0 deletions
diff --git a/drivers/watchdog/sl28cpld_wdt.c b/drivers/watchdog/sl28cpld_wdt.c new file mode 100644 index 000000000..9ce456f09 --- /dev/null +++ b/drivers/watchdog/sl28cpld_wdt.c @@ -0,0 +1,229 @@ +// 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 const 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"); |