// SPDX-License-Identifier: GPL-2.0-only /* * NXP LPC18xx Watchdog Timer (WDT) * * Copyright (c) 2015 Ariel D'Alessandro <ariel@vanguardiasur.com> * * Notes * ----- * The Watchdog consists of a fixed divide-by-4 clock pre-scaler and a 24-bit * counter which decrements on every clock cycle. */ #include <linux/clk.h> #include <linux/io.h> #include <linux/module.h> #include <linux/of.h> #include <linux/platform_device.h> #include <linux/watchdog.h> /* Registers */ #define LPC18XX_WDT_MOD 0x00 #define LPC18XX_WDT_MOD_WDEN BIT(0) #define LPC18XX_WDT_MOD_WDRESET BIT(1) #define LPC18XX_WDT_TC 0x04 #define LPC18XX_WDT_TC_MIN 0xff #define LPC18XX_WDT_TC_MAX 0xffffff #define LPC18XX_WDT_FEED 0x08 #define LPC18XX_WDT_FEED_MAGIC1 0xaa #define LPC18XX_WDT_FEED_MAGIC2 0x55 #define LPC18XX_WDT_TV 0x0c /* Clock pre-scaler */ #define LPC18XX_WDT_CLK_DIV 4 /* Timeout values in seconds */ #define LPC18XX_WDT_DEF_TIMEOUT 30U static int heartbeat; module_param(heartbeat, int, 0); MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds (default=" __MODULE_STRING(LPC18XX_WDT_DEF_TIMEOUT) ")"); 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) ")"); struct lpc18xx_wdt_dev { struct watchdog_device wdt_dev; struct clk *reg_clk; struct clk *wdt_clk; unsigned long clk_rate; void __iomem *base; struct timer_list timer; spinlock_t lock; }; static int lpc18xx_wdt_feed(struct watchdog_device *wdt_dev) { struct lpc18xx_wdt_dev *lpc18xx_wdt = watchdog_get_drvdata(wdt_dev); unsigned long flags; /* * An abort condition will occur if an interrupt happens during the feed * sequence. */ spin_lock_irqsave(&lpc18xx_wdt->lock, flags); writel(LPC18XX_WDT_FEED_MAGIC1, lpc18xx_wdt->base + LPC18XX_WDT_FEED); writel(LPC18XX_WDT_FEED_MAGIC2, lpc18xx_wdt->base + LPC18XX_WDT_FEED); spin_unlock_irqrestore(&lpc18xx_wdt->lock, flags); return 0; } static void lpc18xx_wdt_timer_feed(struct timer_list *t) { struct lpc18xx_wdt_dev *lpc18xx_wdt = from_timer(lpc18xx_wdt, t, timer); struct watchdog_device *wdt_dev = &lpc18xx_wdt->wdt_dev; lpc18xx_wdt_feed(wdt_dev); /* Use safe value (1/2 of real timeout) */ mod_timer(&lpc18xx_wdt->timer, jiffies + msecs_to_jiffies((wdt_dev->timeout * MSEC_PER_SEC) / 2)); } /* * Since LPC18xx Watchdog cannot be disabled in hardware, we must keep feeding * it with a timer until userspace watchdog software takes over. */ static int lpc18xx_wdt_stop(struct watchdog_device *wdt_dev) { struct lpc18xx_wdt_dev *lpc18xx_wdt = watchdog_get_drvdata(wdt_dev); lpc18xx_wdt_timer_feed(&lpc18xx_wdt->timer); return 0; } static void __lpc18xx_wdt_set_timeout(struct lpc18xx_wdt_dev *lpc18xx_wdt) { unsigned int val; val = DIV_ROUND_UP(lpc18xx_wdt->wdt_dev.timeout * lpc18xx_wdt->clk_rate, LPC18XX_WDT_CLK_DIV); writel(val, lpc18xx_wdt->base + LPC18XX_WDT_TC); } static int lpc18xx_wdt_set_timeout(struct watchdog_device *wdt_dev, unsigned int new_timeout) { struct lpc18xx_wdt_dev *lpc18xx_wdt = watchdog_get_drvdata(wdt_dev); lpc18xx_wdt->wdt_dev.timeout = new_timeout; __lpc18xx_wdt_set_timeout(lpc18xx_wdt); return 0; } static unsigned int lpc18xx_wdt_get_timeleft(struct watchdog_device *wdt_dev) { struct lpc18xx_wdt_dev *lpc18xx_wdt = watchdog_get_drvdata(wdt_dev); unsigned int val; val = readl(lpc18xx_wdt->base + LPC18XX_WDT_TV); return (val * LPC18XX_WDT_CLK_DIV) / lpc18xx_wdt->clk_rate; } static int lpc18xx_wdt_start(struct watchdog_device *wdt_dev) { struct lpc18xx_wdt_dev *lpc18xx_wdt = watchdog_get_drvdata(wdt_dev); unsigned int val; if (timer_pending(&lpc18xx_wdt->timer)) del_timer(&lpc18xx_wdt->timer); val = readl(lpc18xx_wdt->base + LPC18XX_WDT_MOD); val |= LPC18XX_WDT_MOD_WDEN; val |= LPC18XX_WDT_MOD_WDRESET; writel(val, lpc18xx_wdt->base + LPC18XX_WDT_MOD); /* * Setting the WDEN bit in the WDMOD register is not sufficient to * enable the Watchdog. A valid feed sequence must be completed after * setting WDEN before the Watchdog is capable of generating a reset. */ lpc18xx_wdt_feed(wdt_dev); return 0; } static int lpc18xx_wdt_restart(struct watchdog_device *wdt_dev, unsigned long action, void *data) { struct lpc18xx_wdt_dev *lpc18xx_wdt = watchdog_get_drvdata(wdt_dev); unsigned long flags; int val; /* * Incorrect feed sequence causes immediate watchdog reset if enabled. */ spin_lock_irqsave(&lpc18xx_wdt->lock, flags); val = readl(lpc18xx_wdt->base + LPC18XX_WDT_MOD); val |= LPC18XX_WDT_MOD_WDEN; val |= LPC18XX_WDT_MOD_WDRESET; writel(val, lpc18xx_wdt->base + LPC18XX_WDT_MOD); writel(LPC18XX_WDT_FEED_MAGIC1, lpc18xx_wdt->base + LPC18XX_WDT_FEED); writel(LPC18XX_WDT_FEED_MAGIC2, lpc18xx_wdt->base + LPC18XX_WDT_FEED); writel(LPC18XX_WDT_FEED_MAGIC1, lpc18xx_wdt->base + LPC18XX_WDT_FEED); writel(LPC18XX_WDT_FEED_MAGIC1, lpc18xx_wdt->base + LPC18XX_WDT_FEED); spin_unlock_irqrestore(&lpc18xx_wdt->lock, flags); return 0; } static const struct watchdog_info lpc18xx_wdt_info = { .identity = "NXP LPC18xx Watchdog", .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE, }; static const struct watchdog_ops lpc18xx_wdt_ops = { .owner = THIS_MODULE, .start = lpc18xx_wdt_start, .stop = lpc18xx_wdt_stop, .ping = lpc18xx_wdt_feed, .set_timeout = lpc18xx_wdt_set_timeout, .get_timeleft = lpc18xx_wdt_get_timeleft, .restart = lpc18xx_wdt_restart, }; static void lpc18xx_clk_disable_unprepare(void *data) { clk_disable_unprepare(data); } static int lpc18xx_wdt_probe(struct platform_device *pdev) { struct lpc18xx_wdt_dev *lpc18xx_wdt; struct device *dev = &pdev->dev; int ret; lpc18xx_wdt = devm_kzalloc(dev, sizeof(*lpc18xx_wdt), GFP_KERNEL); if (!lpc18xx_wdt) return -ENOMEM; lpc18xx_wdt->base = devm_platform_ioremap_resource(pdev, 0); if (IS_ERR(lpc18xx_wdt->base)) return PTR_ERR(lpc18xx_wdt->base); lpc18xx_wdt->reg_clk = devm_clk_get(dev, "reg"); if (IS_ERR(lpc18xx_wdt->reg_clk)) { dev_err(dev, "failed to get the reg clock\n"); return PTR_ERR(lpc18xx_wdt->reg_clk); } lpc18xx_wdt->wdt_clk = devm_clk_get(dev, "wdtclk"); if (IS_ERR(lpc18xx_wdt->wdt_clk)) { dev_err(dev, "failed to get the wdt clock\n"); return PTR_ERR(lpc18xx_wdt->wdt_clk); } ret = clk_prepare_enable(lpc18xx_wdt->reg_clk); if (ret) { dev_err(dev, "could not prepare or enable sys clock\n"); return ret; } ret = devm_add_action_or_reset(dev, lpc18xx_clk_disable_unprepare, lpc18xx_wdt->reg_clk); if (ret) return ret; ret = clk_prepare_enable(lpc18xx_wdt->wdt_clk); if (ret) { dev_err(dev, "could not prepare or enable wdt clock\n"); return ret; } ret = devm_add_action_or_reset(dev, lpc18xx_clk_disable_unprepare, lpc18xx_wdt->wdt_clk); if (ret) return ret; /* We use the clock rate to calculate timeouts */ lpc18xx_wdt->clk_rate = clk_get_rate(lpc18xx_wdt->wdt_clk); if (lpc18xx_wdt->clk_rate == 0) { dev_err(dev, "failed to get clock rate\n"); return -EINVAL; } lpc18xx_wdt->wdt_dev.info = &lpc18xx_wdt_info; lpc18xx_wdt->wdt_dev.ops = &lpc18xx_wdt_ops; lpc18xx_wdt->wdt_dev.min_timeout = DIV_ROUND_UP(LPC18XX_WDT_TC_MIN * LPC18XX_WDT_CLK_DIV, lpc18xx_wdt->clk_rate); lpc18xx_wdt->wdt_dev.max_timeout = (LPC18XX_WDT_TC_MAX * LPC18XX_WDT_CLK_DIV) / lpc18xx_wdt->clk_rate; lpc18xx_wdt->wdt_dev.timeout = min(lpc18xx_wdt->wdt_dev.max_timeout, LPC18XX_WDT_DEF_TIMEOUT); spin_lock_init(&lpc18xx_wdt->lock); lpc18xx_wdt->wdt_dev.parent = dev; watchdog_set_drvdata(&lpc18xx_wdt->wdt_dev, lpc18xx_wdt); watchdog_init_timeout(&lpc18xx_wdt->wdt_dev, heartbeat, dev); __lpc18xx_wdt_set_timeout(lpc18xx_wdt); timer_setup(&lpc18xx_wdt->timer, lpc18xx_wdt_timer_feed, 0); watchdog_set_nowayout(&lpc18xx_wdt->wdt_dev, nowayout); watchdog_set_restart_priority(&lpc18xx_wdt->wdt_dev, 128); platform_set_drvdata(pdev, lpc18xx_wdt); watchdog_stop_on_reboot(&lpc18xx_wdt->wdt_dev); return devm_watchdog_register_device(dev, &lpc18xx_wdt->wdt_dev); } static int lpc18xx_wdt_remove(struct platform_device *pdev) { struct lpc18xx_wdt_dev *lpc18xx_wdt = platform_get_drvdata(pdev); dev_warn(&pdev->dev, "I quit now, hardware will probably reboot!\n"); del_timer(&lpc18xx_wdt->timer); return 0; } static const struct of_device_id lpc18xx_wdt_match[] = { { .compatible = "nxp,lpc1850-wwdt" }, {} }; MODULE_DEVICE_TABLE(of, lpc18xx_wdt_match); static struct platform_driver lpc18xx_wdt_driver = { .driver = { .name = "lpc18xx-wdt", .of_match_table = lpc18xx_wdt_match, }, .probe = lpc18xx_wdt_probe, .remove = lpc18xx_wdt_remove, }; module_platform_driver(lpc18xx_wdt_driver); MODULE_AUTHOR("Ariel D'Alessandro <ariel@vanguardiasur.com.ar>"); MODULE_DESCRIPTION("NXP LPC18xx Watchdog Timer Driver"); MODULE_LICENSE("GPL v2");