--- /dev/null
+/*
+ * NXP LPC18xx Watchdog Timer (WDT)
+ *
+ * Copyright (c) 2015 Ariel D'Alessandro <ariel@vanguardiasur.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * 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/reboot.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;
+ struct notifier_block restart_handler;
+ 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(unsigned long data)
+{
+ struct watchdog_device *wdt_dev = (struct watchdog_device *)data;
+ struct lpc18xx_wdt_dev *lpc18xx_wdt = watchdog_get_drvdata(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)
+{
+ lpc18xx_wdt_timer_feed((unsigned long)wdt_dev);
+
+ 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 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,
+};
+
+static int lpc18xx_wdt_restart(struct notifier_block *this, unsigned long mode,
+ void *cmd)
+{
+ struct lpc18xx_wdt_dev *lpc18xx_wdt = container_of(this,
+ struct lpc18xx_wdt_dev, restart_handler);
+ 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 NOTIFY_OK;
+}
+
+static int lpc18xx_wdt_probe(struct platform_device *pdev)
+{
+ struct lpc18xx_wdt_dev *lpc18xx_wdt;
+ struct device *dev = &pdev->dev;
+ struct resource *res;
+ int ret;
+
+ lpc18xx_wdt = devm_kzalloc(dev, sizeof(*lpc18xx_wdt), GFP_KERNEL);
+ if (!lpc18xx_wdt)
+ return -ENOMEM;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ lpc18xx_wdt->base = devm_ioremap_resource(dev, res);
+ 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 = clk_prepare_enable(lpc18xx_wdt->wdt_clk);
+ if (ret) {
+ dev_err(dev, "could not prepare or enable wdt clock\n");
+ goto disable_reg_clk;
+ }
+
+ /* 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");
+ ret = -EINVAL;
+ goto disable_wdt_clk;
+ }
+
+ 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);
+
+ ret = watchdog_init_timeout(&lpc18xx_wdt->wdt_dev, heartbeat, dev);
+
+ __lpc18xx_wdt_set_timeout(lpc18xx_wdt);
+
+ setup_timer(&lpc18xx_wdt->timer, lpc18xx_wdt_timer_feed,
+ (unsigned long)&lpc18xx_wdt->wdt_dev);
+
+ watchdog_set_nowayout(&lpc18xx_wdt->wdt_dev, nowayout);
+
+ platform_set_drvdata(pdev, lpc18xx_wdt);
+
+ ret = watchdog_register_device(&lpc18xx_wdt->wdt_dev);
+ if (ret)
+ goto disable_wdt_clk;
+
+ lpc18xx_wdt->restart_handler.notifier_call = lpc18xx_wdt_restart;
+ lpc18xx_wdt->restart_handler.priority = 128;
+ ret = register_restart_handler(&lpc18xx_wdt->restart_handler);
+ if (ret)
+ dev_warn(dev, "failed to register restart handler: %d\n", ret);
+
+ return 0;
+
+disable_wdt_clk:
+ clk_disable_unprepare(lpc18xx_wdt->wdt_clk);
+disable_reg_clk:
+ clk_disable_unprepare(lpc18xx_wdt->reg_clk);
+ return ret;
+}
+
+static void lpc18xx_wdt_shutdown(struct platform_device *pdev)
+{
+ struct lpc18xx_wdt_dev *lpc18xx_wdt = platform_get_drvdata(pdev);
+
+ lpc18xx_wdt_stop(&lpc18xx_wdt->wdt_dev);
+}
+
+static int lpc18xx_wdt_remove(struct platform_device *pdev)
+{
+ struct lpc18xx_wdt_dev *lpc18xx_wdt = platform_get_drvdata(pdev);
+
+ unregister_restart_handler(&lpc18xx_wdt->restart_handler);
+
+ dev_warn(&pdev->dev, "I quit now, hardware will probably reboot!\n");
+ del_timer(&lpc18xx_wdt->timer);
+
+ watchdog_unregister_device(&lpc18xx_wdt->wdt_dev);
+ clk_disable_unprepare(lpc18xx_wdt->wdt_clk);
+ clk_disable_unprepare(lpc18xx_wdt->reg_clk);
+
+ 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,
+ .shutdown = lpc18xx_wdt_shutdown,
+};
+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");
Code Review / kvmfornfv.git / blobdiff