diff options
Diffstat (limited to 'drivers/watchdog/s32g_wdt.c')
| -rw-r--r-- | drivers/watchdog/s32g_wdt.c | 315 |
1 files changed, 315 insertions, 0 deletions
diff --git a/drivers/watchdog/s32g_wdt.c b/drivers/watchdog/s32g_wdt.c new file mode 100644 index 000000000000..ad55063060af --- /dev/null +++ b/drivers/watchdog/s32g_wdt.c @@ -0,0 +1,315 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Watchdog driver for S32G SoC + * + * Copyright 2017-2019, 2021-2025 NXP. + * + */ +#include <linux/clk.h> +#include <linux/debugfs.h> +#include <linux/io.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/moduleparam.h> +#include <linux/of.h> +#include <linux/platform_device.h> +#include <linux/watchdog.h> + +#define DRIVER_NAME "s32g-swt" + +#define S32G_SWT_CR(__base) ((__base) + 0x00) /* Control Register offset */ +#define S32G_SWT_CR_SM (BIT(9) | BIT(10)) /* -> Service Mode */ +#define S32G_SWT_CR_STP BIT(2) /* -> Stop Mode Control */ +#define S32G_SWT_CR_FRZ BIT(1) /* -> Debug Mode Control */ +#define S32G_SWT_CR_WEN BIT(0) /* -> Watchdog Enable */ + +#define S32G_SWT_TO(__base) ((__base) + 0x08) /* Timeout Register offset */ + +#define S32G_SWT_SR(__base) ((__base) + 0x10) /* Service Register offset */ +#define S32G_WDT_SEQ1 0xA602 /* -> service sequence number 1 */ +#define S32G_WDT_SEQ2 0xB480 /* -> service sequence number 2 */ + +#define S32G_SWT_CO(__base) ((__base) + 0x14) /* Counter output register */ + +#define S32G_WDT_DEFAULT_TIMEOUT 30 + +struct s32g_wdt_device { + int rate; + void __iomem *base; + struct watchdog_device wdog; +}; + +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 unsigned int timeout_param = S32G_WDT_DEFAULT_TIMEOUT; +module_param(timeout_param, uint, 0); +MODULE_PARM_DESC(timeout_param, "Watchdog timeout in seconds (default=" + __MODULE_STRING(S32G_WDT_DEFAULT_TIMEOUT) ")"); + +static bool early_enable; +module_param(early_enable, bool, 0); +MODULE_PARM_DESC(early_enable, + "Watchdog is started on module insertion (default=false)"); + +static const struct watchdog_info s32g_wdt_info = { + .identity = "s32g watchdog", + .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | + WDIOC_GETTIMEOUT | WDIOC_GETTIMELEFT, +}; + +static struct s32g_wdt_device *wdd_to_s32g_wdt(struct watchdog_device *wdd) +{ + return container_of(wdd, struct s32g_wdt_device, wdog); +} + +static unsigned int wdog_sec_to_count(struct s32g_wdt_device *wdev, unsigned int timeout) +{ + return wdev->rate * timeout; +} + +static int s32g_wdt_ping(struct watchdog_device *wdog) +{ + struct s32g_wdt_device *wdev = wdd_to_s32g_wdt(wdog); + + writel(S32G_WDT_SEQ1, S32G_SWT_SR(wdev->base)); + writel(S32G_WDT_SEQ2, S32G_SWT_SR(wdev->base)); + + return 0; +} + +static int s32g_wdt_start(struct watchdog_device *wdog) +{ + struct s32g_wdt_device *wdev = wdd_to_s32g_wdt(wdog); + unsigned long val; + + val = readl(S32G_SWT_CR(wdev->base)); + + val |= S32G_SWT_CR_WEN; + + writel(val, S32G_SWT_CR(wdev->base)); + + return 0; +} + +static int s32g_wdt_stop(struct watchdog_device *wdog) +{ + struct s32g_wdt_device *wdev = wdd_to_s32g_wdt(wdog); + unsigned long val; + + val = readl(S32G_SWT_CR(wdev->base)); + + val &= ~S32G_SWT_CR_WEN; + + writel(val, S32G_SWT_CR(wdev->base)); + + return 0; +} + +static int s32g_wdt_set_timeout(struct watchdog_device *wdog, unsigned int timeout) +{ + struct s32g_wdt_device *wdev = wdd_to_s32g_wdt(wdog); + + writel(wdog_sec_to_count(wdev, timeout), S32G_SWT_TO(wdev->base)); + + wdog->timeout = timeout; + + /* + * Conforming to the documentation, the timeout counter is + * loaded when servicing is operated (aka ping) or when the + * counter is enabled. In case the watchdog is already started + * it must be stopped and started again to update the timeout + * register or a ping can be sent to refresh the counter. Here + * we choose to send a ping to the watchdog which is harmless + * if the watchdog is stopped. + */ + return s32g_wdt_ping(wdog); +} + +static unsigned int s32g_wdt_get_timeleft(struct watchdog_device *wdog) +{ + struct s32g_wdt_device *wdev = wdd_to_s32g_wdt(wdog); + unsigned long counter; + bool is_running; + + /* + * The counter output can be read only if the SWT is + * disabled. Given the latency between the internal counter + * and the counter output update, there can be very small + * difference. However, we can accept this matter of fact + * given the resolution is a second based unit for the output. + */ + is_running = watchdog_hw_running(wdog); + + if (is_running) + s32g_wdt_stop(wdog); + + counter = readl(S32G_SWT_CO(wdev->base)); + + if (is_running) + s32g_wdt_start(wdog); + + return counter / wdev->rate; +} + +static const struct watchdog_ops s32g_wdt_ops = { + .owner = THIS_MODULE, + .start = s32g_wdt_start, + .stop = s32g_wdt_stop, + .ping = s32g_wdt_ping, + .set_timeout = s32g_wdt_set_timeout, + .get_timeleft = s32g_wdt_get_timeleft, +}; + +static void s32g_wdt_init(struct s32g_wdt_device *wdev) +{ + unsigned long val; + + /* Set the watchdog's Time-Out value */ + val = wdog_sec_to_count(wdev, wdev->wdog.timeout); + + writel(val, S32G_SWT_TO(wdev->base)); + + /* + * Get the control register content. We are at init time, the + * watchdog should not be started. + */ + val = readl(S32G_SWT_CR(wdev->base)); + + /* + * We want to allow the watchdog timer to be stopped when + * device enters debug mode. + */ + val |= S32G_SWT_CR_FRZ; + + /* + * However, when the CPU is in WFI or suspend mode, the + * watchdog must continue. The documentation refers it as the + * stopped mode. + */ + val &= ~S32G_SWT_CR_STP; + + /* + * Use Fixed Service Sequence to ping the watchdog which is + * 0x00 configuration value for the service mode. It should be + * already set because it is the default value but we reset it + * in case. + */ + val &= ~S32G_SWT_CR_SM; + + writel(val, S32G_SWT_CR(wdev->base)); + + /* + * When the 'early_enable' option is set, we start the + * watchdog from the kernel. + */ + if (early_enable) { + s32g_wdt_start(&wdev->wdog); + set_bit(WDOG_HW_RUNNING, &wdev->wdog.status); + } +} + +static int s32g_wdt_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct resource *res; + struct clk *clk; + struct s32g_wdt_device *wdev; + struct watchdog_device *wdog; + int ret; + + wdev = devm_kzalloc(dev, sizeof(*wdev), GFP_KERNEL); + if (!wdev) + return -ENOMEM; + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + wdev->base = devm_ioremap_resource(dev, res); + if (IS_ERR(wdev->base)) + return dev_err_probe(&pdev->dev, PTR_ERR(wdev->base), "Can not get resource\n"); + + clk = devm_clk_get_enabled(dev, "counter"); + if (IS_ERR(clk)) + return dev_err_probe(dev, PTR_ERR(clk), "Can't get Watchdog clock\n"); + + wdev->rate = clk_get_rate(clk); + if (!wdev->rate) { + dev_err(dev, "Input clock rate is not valid\n"); + return -EINVAL; + } + + wdog = &wdev->wdog; + wdog->info = &s32g_wdt_info; + wdog->ops = &s32g_wdt_ops; + + /* + * The code converts the timeout into a counter a value, if + * the value is less than 0x100, then it is clamped by the SWT + * module, so it is safe to specify a zero value as the + * minimum timeout. + */ + wdog->min_timeout = 0; + + /* + * The counter register is a 32 bits long, so the maximum + * counter value is UINT_MAX and the timeout in second is the + * value divided by the rate. + * + * For instance, a rate of 51MHz lead to 84 seconds maximum + * timeout. + */ + wdog->max_timeout = UINT_MAX / wdev->rate; + + /* + * The module param and the DT 'timeout-sec' property will + * override the default value if they are specified. + */ + ret = watchdog_init_timeout(wdog, timeout_param, dev); + if (ret) + return ret; + + /* + * As soon as the watchdog is started, there is no way to stop + * it if the 'nowayout' option is set at boot time + */ + watchdog_set_nowayout(wdog, nowayout); + + /* + * The devm_ version of the watchdog_register_device() + * function will call watchdog_unregister_device() when the + * device is removed. + */ + watchdog_stop_on_unregister(wdog); + + s32g_wdt_init(wdev); + + ret = devm_watchdog_register_device(dev, wdog); + if (ret) + return dev_err_probe(dev, ret, "Cannot register watchdog device\n"); + + dev_info(dev, "S32G Watchdog Timer Registered, timeout=%ds, nowayout=%d, early_enable=%d\n", + wdog->timeout, nowayout, early_enable); + + return 0; +} + +static const struct of_device_id s32g_wdt_dt_ids[] = { + { .compatible = "nxp,s32g2-swt" }, + { /* sentinel */ } +}; +MODULE_DEVICE_TABLE(of, s32g_wdt_dt_ids); + +static struct platform_driver s32g_wdt_driver = { + .probe = s32g_wdt_probe, + .driver = { + .name = DRIVER_NAME, + .of_match_table = s32g_wdt_dt_ids, + }, +}; + +module_platform_driver(s32g_wdt_driver); + +MODULE_AUTHOR("Daniel Lezcano <daniel.lezcano@linaro.org>"); +MODULE_DESCRIPTION("Watchdog driver for S32G SoC"); +MODULE_LICENSE("GPL"); |