--- /dev/null
+/*
+ * watchdog driver for ZTE's zx2967 family
+ *
+ * Copyright (C) 2017 ZTE Ltd.
+ *
+ * Author: Baoyou Xie <baoyou.xie@linaro.org>
+ *
+ * License terms: GNU General Public License (GPL) version 2
+ */
+
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/reset.h>
+#include <linux/watchdog.h>
+
+#define ZX2967_WDT_CFG_REG 0x4
+#define ZX2967_WDT_LOAD_REG 0x8
+#define ZX2967_WDT_REFRESH_REG 0x18
+#define ZX2967_WDT_START_REG 0x1c
+
+#define ZX2967_WDT_REFRESH_MASK GENMASK(5, 0)
+
+#define ZX2967_WDT_CFG_DIV(n) ((((n) & 0xff) - 1) << 8)
+#define ZX2967_WDT_START_EN 0x1
+
+/*
+ * Hardware magic number.
+ * When watchdog reg is written, the lowest 16 bits are valid, but
+ * the highest 16 bits should be always this number.
+ */
+#define ZX2967_WDT_WRITEKEY (0x1234 << 16)
+#define ZX2967_WDT_VAL_MASK GENMASK(15, 0)
+
+#define ZX2967_WDT_DIV_DEFAULT 16
+#define ZX2967_WDT_DEFAULT_TIMEOUT 32
+#define ZX2967_WDT_MIN_TIMEOUT 1
+#define ZX2967_WDT_MAX_TIMEOUT 524
+#define ZX2967_WDT_MAX_COUNT 0xffff
+
+#define ZX2967_WDT_CLK_FREQ 0x8000
+
+#define ZX2967_WDT_FLAG_REBOOT_MON BIT(0)
+
+struct zx2967_wdt {
+ struct watchdog_device wdt_device;
+ void __iomem *reg_base;
+ struct clk *clock;
+};
+
+static inline u32 zx2967_wdt_readl(struct zx2967_wdt *wdt, u16 reg)
+{
+ return readl_relaxed(wdt->reg_base + reg);
+}
+
+static inline void zx2967_wdt_writel(struct zx2967_wdt *wdt, u16 reg, u32 val)
+{
+ writel_relaxed(val | ZX2967_WDT_WRITEKEY, wdt->reg_base + reg);
+}
+
+static void zx2967_wdt_refresh(struct zx2967_wdt *wdt)
+{
+ u32 val;
+
+ val = zx2967_wdt_readl(wdt, ZX2967_WDT_REFRESH_REG);
+ /*
+ * Bit 4-5, 1 and 2: refresh config info
+ * Bit 2-3, 1 and 2: refresh counter
+ * Bit 0-1, 1 and 2: refresh int-value
+ * we shift each group value between 1 and 2 to refresh all data.
+ */
+ val ^= ZX2967_WDT_REFRESH_MASK;
+ zx2967_wdt_writel(wdt, ZX2967_WDT_REFRESH_REG,
+ val & ZX2967_WDT_VAL_MASK);
+}
+
+static int
+zx2967_wdt_set_timeout(struct watchdog_device *wdd, unsigned int timeout)
+{
+ struct zx2967_wdt *wdt = watchdog_get_drvdata(wdd);
+ unsigned int divisor = ZX2967_WDT_DIV_DEFAULT;
+ u32 count;
+
+ count = timeout * ZX2967_WDT_CLK_FREQ;
+ if (count > divisor * ZX2967_WDT_MAX_COUNT)
+ divisor = DIV_ROUND_UP(count, ZX2967_WDT_MAX_COUNT);
+ count = DIV_ROUND_UP(count, divisor);
+ zx2967_wdt_writel(wdt, ZX2967_WDT_CFG_REG,
+ ZX2967_WDT_CFG_DIV(divisor) & ZX2967_WDT_VAL_MASK);
+ zx2967_wdt_writel(wdt, ZX2967_WDT_LOAD_REG,
+ count & ZX2967_WDT_VAL_MASK);
+ zx2967_wdt_refresh(wdt);
+ wdd->timeout = (count * divisor) / ZX2967_WDT_CLK_FREQ;
+
+ return 0;
+}
+
+static void __zx2967_wdt_start(struct zx2967_wdt *wdt)
+{
+ u32 val;
+
+ val = zx2967_wdt_readl(wdt, ZX2967_WDT_START_REG);
+ val |= ZX2967_WDT_START_EN;
+ zx2967_wdt_writel(wdt, ZX2967_WDT_START_REG,
+ val & ZX2967_WDT_VAL_MASK);
+}
+
+static void __zx2967_wdt_stop(struct zx2967_wdt *wdt)
+{
+ u32 val;
+
+ val = zx2967_wdt_readl(wdt, ZX2967_WDT_START_REG);
+ val &= ~ZX2967_WDT_START_EN;
+ zx2967_wdt_writel(wdt, ZX2967_WDT_START_REG,
+ val & ZX2967_WDT_VAL_MASK);
+}
+
+static int zx2967_wdt_start(struct watchdog_device *wdd)
+{
+ struct zx2967_wdt *wdt = watchdog_get_drvdata(wdd);
+
+ zx2967_wdt_set_timeout(wdd, wdd->timeout);
+ __zx2967_wdt_start(wdt);
+
+ return 0;
+}
+
+static int zx2967_wdt_stop(struct watchdog_device *wdd)
+{
+ struct zx2967_wdt *wdt = watchdog_get_drvdata(wdd);
+
+ __zx2967_wdt_stop(wdt);
+
+ return 0;
+}
+
+static int zx2967_wdt_keepalive(struct watchdog_device *wdd)
+{
+ struct zx2967_wdt *wdt = watchdog_get_drvdata(wdd);
+
+ zx2967_wdt_refresh(wdt);
+
+ return 0;
+}
+
+#define ZX2967_WDT_OPTIONS \
+ (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE)
+static const struct watchdog_info zx2967_wdt_ident = {
+ .options = ZX2967_WDT_OPTIONS,
+ .identity = "zx2967 watchdog",
+};
+
+static struct watchdog_ops zx2967_wdt_ops = {
+ .owner = THIS_MODULE,
+ .start = zx2967_wdt_start,
+ .stop = zx2967_wdt_stop,
+ .ping = zx2967_wdt_keepalive,
+ .set_timeout = zx2967_wdt_set_timeout,
+};
+
+static void zx2967_wdt_reset_sysctrl(struct device *dev)
+{
+ int ret;
+ void __iomem *regmap;
+ unsigned int offset, mask, config;
+ struct of_phandle_args out_args;
+
+ ret = of_parse_phandle_with_fixed_args(dev->of_node,
+ "zte,wdt-reset-sysctrl", 3, 0, &out_args);
+ if (ret)
+ return;
+
+ offset = out_args.args[0];
+ config = out_args.args[1];
+ mask = out_args.args[2];
+
+ regmap = syscon_node_to_regmap(out_args.np);
+ if (IS_ERR(regmap)) {
+ of_node_put(out_args.np);
+ return;
+ }
+
+ regmap_update_bits(regmap, offset, mask, config);
+ of_node_put(out_args.np);
+}
+
+static int zx2967_wdt_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct zx2967_wdt *wdt;
+ struct resource *base;
+ int ret;
+ struct reset_control *rstc;
+
+ wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
+ if (!wdt)
+ return -ENOMEM;
+
+ platform_set_drvdata(pdev, wdt);
+
+ wdt->wdt_device.info = &zx2967_wdt_ident;
+ wdt->wdt_device.ops = &zx2967_wdt_ops;
+ wdt->wdt_device.timeout = ZX2967_WDT_DEFAULT_TIMEOUT;
+ wdt->wdt_device.max_timeout = ZX2967_WDT_MAX_TIMEOUT;
+ wdt->wdt_device.min_timeout = ZX2967_WDT_MIN_TIMEOUT;
+ wdt->wdt_device.parent = &pdev->dev;
+
+ base = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ wdt->reg_base = devm_ioremap_resource(dev, base);
+ if (IS_ERR(wdt->reg_base)) {
+ dev_err(dev, "ioremap failed\n");
+ return PTR_ERR(wdt->reg_base);
+ }
+
+ zx2967_wdt_reset_sysctrl(dev);
+
+ wdt->clock = devm_clk_get(dev, NULL);
+ if (IS_ERR(wdt->clock)) {
+ dev_err(dev, "failed to find watchdog clock source\n");
+ return PTR_ERR(wdt->clock);
+ }
+
+ ret = clk_prepare_enable(wdt->clock);
+ if (ret < 0) {
+ dev_err(dev, "failed to enable clock\n");
+ return ret;
+ }
+ clk_set_rate(wdt->clock, ZX2967_WDT_CLK_FREQ);
+
+ rstc = devm_reset_control_get(dev, NULL);
+ if (IS_ERR(rstc)) {
+ dev_err(dev, "failed to get rstc");
+ ret = PTR_ERR(rstc);
+ goto err;
+ }
+
+ reset_control_assert(rstc);
+ reset_control_deassert(rstc);
+
+ watchdog_set_drvdata(&wdt->wdt_device, wdt);
+ watchdog_init_timeout(&wdt->wdt_device,
+ ZX2967_WDT_DEFAULT_TIMEOUT, dev);
+ watchdog_set_nowayout(&wdt->wdt_device, WATCHDOG_NOWAYOUT);
+
+ ret = watchdog_register_device(&wdt->wdt_device);
+ if (ret)
+ goto err;
+
+ dev_info(dev, "watchdog enabled (timeout=%d sec, nowayout=%d)",
+ wdt->wdt_device.timeout, WATCHDOG_NOWAYOUT);
+
+ return 0;
+
+err:
+ clk_disable_unprepare(wdt->clock);
+ return ret;
+}
+
+static int zx2967_wdt_remove(struct platform_device *pdev)
+{
+ struct zx2967_wdt *wdt = platform_get_drvdata(pdev);
+
+ watchdog_unregister_device(&wdt->wdt_device);
+ clk_disable_unprepare(wdt->clock);
+
+ return 0;
+}
+
+static const struct of_device_id zx2967_wdt_match[] = {
+ { .compatible = "zte,zx296718-wdt", },
+ {}
+};
+MODULE_DEVICE_TABLE(of, zx2967_wdt_match);
+
+static struct platform_driver zx2967_wdt_driver = {
+ .probe = zx2967_wdt_probe,
+ .remove = zx2967_wdt_remove,
+ .driver = {
+ .name = "zx2967-wdt",
+ .of_match_table = of_match_ptr(zx2967_wdt_match),
+ },
+};
+module_platform_driver(zx2967_wdt_driver);
+
+MODULE_AUTHOR("Baoyou Xie <baoyou.xie@linaro.org>");
+MODULE_DESCRIPTION("ZTE zx2967 Watchdog Device Driver");
+MODULE_LICENSE("GPL v2");
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