--- /dev/null
+/*
+ * ST's LPC Watchdog
+ *
+ * Copyright (C) 2014 STMicroelectronics -- All Rights Reserved
+ *
+ * Author: David Paris <david.paris@st.com> for STMicroelectronics
+ * Lee Jones <lee.jones@linaro.org> for STMicroelectronics
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#include <linux/clk.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/watchdog.h>
+
+#include <dt-bindings/mfd/st-lpc.h>
+
+/* Low Power Alarm */
+#define LPC_LPA_LSB_OFF 0x410
+#define LPC_LPA_START_OFF 0x418
+
+/* LPC as WDT */
+#define LPC_WDT_OFF 0x510
+
+static struct watchdog_device st_wdog_dev;
+
+struct st_wdog_syscfg {
+ unsigned int reset_type_reg;
+ unsigned int reset_type_mask;
+ unsigned int enable_reg;
+ unsigned int enable_mask;
+};
+
+struct st_wdog {
+ void __iomem *base;
+ struct device *dev;
+ struct regmap *regmap;
+ struct st_wdog_syscfg *syscfg;
+ struct clk *clk;
+ unsigned long clkrate;
+ bool warm_reset;
+};
+
+static struct st_wdog_syscfg stid127_syscfg = {
+ .reset_type_reg = 0x004,
+ .reset_type_mask = BIT(2),
+ .enable_reg = 0x000,
+ .enable_mask = BIT(2),
+};
+
+static struct st_wdog_syscfg stih415_syscfg = {
+ .reset_type_reg = 0x0B8,
+ .reset_type_mask = BIT(6),
+ .enable_reg = 0x0B4,
+ .enable_mask = BIT(7),
+};
+
+static struct st_wdog_syscfg stih416_syscfg = {
+ .reset_type_reg = 0x88C,
+ .reset_type_mask = BIT(6),
+ .enable_reg = 0x888,
+ .enable_mask = BIT(7),
+};
+
+static struct st_wdog_syscfg stih407_syscfg = {
+ .enable_reg = 0x204,
+ .enable_mask = BIT(19),
+};
+
+static const struct of_device_id st_wdog_match[] = {
+ {
+ .compatible = "st,stih407-lpc",
+ .data = &stih407_syscfg,
+ },
+ {
+ .compatible = "st,stih416-lpc",
+ .data = &stih416_syscfg,
+ },
+ {
+ .compatible = "st,stih415-lpc",
+ .data = &stih415_syscfg,
+ },
+ {
+ .compatible = "st,stid127-lpc",
+ .data = &stid127_syscfg,
+ },
+ {},
+};
+MODULE_DEVICE_TABLE(of, st_wdog_match);
+
+static void st_wdog_setup(struct st_wdog *st_wdog, bool enable)
+{
+ /* Type of watchdog reset - 0: Cold 1: Warm */
+ if (st_wdog->syscfg->reset_type_reg)
+ regmap_update_bits(st_wdog->regmap,
+ st_wdog->syscfg->reset_type_reg,
+ st_wdog->syscfg->reset_type_mask,
+ st_wdog->warm_reset);
+
+ /* Mask/unmask watchdog reset */
+ regmap_update_bits(st_wdog->regmap,
+ st_wdog->syscfg->enable_reg,
+ st_wdog->syscfg->enable_mask,
+ enable ? 0 : st_wdog->syscfg->enable_mask);
+}
+
+static void st_wdog_load_timer(struct st_wdog *st_wdog, unsigned int timeout)
+{
+ unsigned long clkrate = st_wdog->clkrate;
+
+ writel_relaxed(timeout * clkrate, st_wdog->base + LPC_LPA_LSB_OFF);
+ writel_relaxed(1, st_wdog->base + LPC_LPA_START_OFF);
+}
+
+static int st_wdog_start(struct watchdog_device *wdd)
+{
+ struct st_wdog *st_wdog = watchdog_get_drvdata(wdd);
+
+ writel_relaxed(1, st_wdog->base + LPC_WDT_OFF);
+
+ return 0;
+}
+
+static int st_wdog_stop(struct watchdog_device *wdd)
+{
+ struct st_wdog *st_wdog = watchdog_get_drvdata(wdd);
+
+ writel_relaxed(0, st_wdog->base + LPC_WDT_OFF);
+
+ return 0;
+}
+
+static int st_wdog_set_timeout(struct watchdog_device *wdd,
+ unsigned int timeout)
+{
+ struct st_wdog *st_wdog = watchdog_get_drvdata(wdd);
+
+ wdd->timeout = timeout;
+ st_wdog_load_timer(st_wdog, timeout);
+
+ return 0;
+}
+
+static int st_wdog_keepalive(struct watchdog_device *wdd)
+{
+ struct st_wdog *st_wdog = watchdog_get_drvdata(wdd);
+
+ st_wdog_load_timer(st_wdog, wdd->timeout);
+
+ return 0;
+}
+
+static const struct watchdog_info st_wdog_info = {
+ .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
+ .identity = "ST LPC WDT",
+};
+
+static const struct watchdog_ops st_wdog_ops = {
+ .owner = THIS_MODULE,
+ .start = st_wdog_start,
+ .stop = st_wdog_stop,
+ .ping = st_wdog_keepalive,
+ .set_timeout = st_wdog_set_timeout,
+};
+
+static struct watchdog_device st_wdog_dev = {
+ .info = &st_wdog_info,
+ .ops = &st_wdog_ops,
+};
+
+static int st_wdog_probe(struct platform_device *pdev)
+{
+ const struct of_device_id *match;
+ struct device_node *np = pdev->dev.of_node;
+ struct st_wdog *st_wdog;
+ struct regmap *regmap;
+ struct resource *res;
+ struct clk *clk;
+ void __iomem *base;
+ uint32_t mode;
+ int ret;
+
+ ret = of_property_read_u32(np, "st,lpc-mode", &mode);
+ if (ret) {
+ dev_err(&pdev->dev, "An LPC mode must be provided\n");
+ return -EINVAL;
+ }
+
+ /* LPC can either run in RTC or WDT mode */
+ if (mode != ST_LPC_MODE_WDT)
+ return -ENODEV;
+
+ st_wdog = devm_kzalloc(&pdev->dev, sizeof(*st_wdog), GFP_KERNEL);
+ if (!st_wdog)
+ return -ENOMEM;
+
+ match = of_match_device(st_wdog_match, &pdev->dev);
+ if (!match) {
+ dev_err(&pdev->dev, "Couldn't match device\n");
+ return -ENODEV;
+ }
+ st_wdog->syscfg = (struct st_wdog_syscfg *)match->data;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ base = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(base))
+ return PTR_ERR(base);
+
+ regmap = syscon_regmap_lookup_by_phandle(np, "st,syscfg");
+ if (IS_ERR(regmap)) {
+ dev_err(&pdev->dev, "No syscfg phandle specified\n");
+ return PTR_ERR(regmap);
+ }
+
+ clk = devm_clk_get(&pdev->dev, NULL);
+ if (IS_ERR(clk)) {
+ dev_err(&pdev->dev, "Unable to request clock\n");
+ return PTR_ERR(clk);
+ }
+
+ st_wdog->dev = &pdev->dev;
+ st_wdog->base = base;
+ st_wdog->clk = clk;
+ st_wdog->regmap = regmap;
+ st_wdog->warm_reset = of_property_read_bool(np, "st,warm_reset");
+ st_wdog->clkrate = clk_get_rate(st_wdog->clk);
+
+ if (!st_wdog->clkrate) {
+ dev_err(&pdev->dev, "Unable to fetch clock rate\n");
+ return -EINVAL;
+ }
+ st_wdog_dev.max_timeout = 0xFFFFFFFF / st_wdog->clkrate;
+
+ ret = clk_prepare_enable(clk);
+ if (ret) {
+ dev_err(&pdev->dev, "Unable to enable clock\n");
+ return ret;
+ }
+
+ watchdog_set_drvdata(&st_wdog_dev, st_wdog);
+ watchdog_set_nowayout(&st_wdog_dev, WATCHDOG_NOWAYOUT);
+
+ /* Init Watchdog timeout with value in DT */
+ ret = watchdog_init_timeout(&st_wdog_dev, 0, &pdev->dev);
+ if (ret) {
+ dev_err(&pdev->dev, "Unable to initialise watchdog timeout\n");
+ clk_disable_unprepare(clk);
+ return ret;
+ }
+
+ ret = watchdog_register_device(&st_wdog_dev);
+ if (ret) {
+ dev_err(&pdev->dev, "Unable to register watchdog\n");
+ clk_disable_unprepare(clk);
+ return ret;
+ }
+
+ st_wdog_setup(st_wdog, true);
+
+ dev_info(&pdev->dev, "LPC Watchdog driver registered, reset type is %s",
+ st_wdog->warm_reset ? "warm" : "cold");
+
+ return ret;
+}
+
+static int st_wdog_remove(struct platform_device *pdev)
+{
+ struct st_wdog *st_wdog = watchdog_get_drvdata(&st_wdog_dev);
+
+ st_wdog_setup(st_wdog, false);
+ watchdog_unregister_device(&st_wdog_dev);
+ clk_disable_unprepare(st_wdog->clk);
+
+ return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int st_wdog_suspend(struct device *dev)
+{
+ struct st_wdog *st_wdog = watchdog_get_drvdata(&st_wdog_dev);
+
+ if (watchdog_active(&st_wdog_dev))
+ st_wdog_stop(&st_wdog_dev);
+
+ st_wdog_setup(st_wdog, false);
+
+ clk_disable(st_wdog->clk);
+
+ return 0;
+}
+
+static int st_wdog_resume(struct device *dev)
+{
+ struct st_wdog *st_wdog = watchdog_get_drvdata(&st_wdog_dev);
+ int ret;
+
+ ret = clk_enable(st_wdog->clk);
+ if (ret) {
+ dev_err(dev, "Unable to re-enable clock\n");
+ watchdog_unregister_device(&st_wdog_dev);
+ clk_unprepare(st_wdog->clk);
+ return ret;
+ }
+
+ st_wdog_setup(st_wdog, true);
+
+ if (watchdog_active(&st_wdog_dev)) {
+ st_wdog_load_timer(st_wdog, st_wdog_dev.timeout);
+ st_wdog_start(&st_wdog_dev);
+ }
+
+ return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(st_wdog_pm_ops,
+ st_wdog_suspend,
+ st_wdog_resume);
+
+static struct platform_driver st_wdog_driver = {
+ .driver = {
+ .name = "st-lpc-wdt",
+ .pm = &st_wdog_pm_ops,
+ .of_match_table = st_wdog_match,
+ },
+ .probe = st_wdog_probe,
+ .remove = st_wdog_remove,
+};
+module_platform_driver(st_wdog_driver);
+
+MODULE_AUTHOR("David Paris <david.paris@st.com>");
+MODULE_DESCRIPTION("ST LPC Watchdog Driver");
+MODULE_LICENSE("GPL");
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