watchdog: atlas7: add watchdog driver of CSRatlas7

This patch adds watchdog driver for CSRatlas7 platform.
On CSRatlas7, the 6th timer can act as a watchdog timer
when the Watchdog mode is enabled.

Signed-off-by: Guo Zeng <Guo.Zeng@csr.com>
Signed-off-by: William Wang <William.Wang@csr.com>
Signed-off-by: Barry Song <Baohua.Song@csr.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

3 files changed, 253 insertions, 0 deletions

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 71e47dde7d4a..2116e088fd25 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -585,6 +585,16 @@ config LPC18XX_WATCHDOG
           To compile this driver as a module, choose M here: the
           module will be called lpc18xx_wdt.
 
+config ATLAS7_WATCHDOG
+        tristate "CSRatlas7 watchdog"
+        depends on ARCH_ATLAS7
+        help
+          Say Y here to include Watchdog timer support for the watchdog
+          existing on the CSRatlas7 series platforms.
+
+          To compile this driver as a module, choose M here: the
+          module will be called atlas7_wdt.
+
 # AVR32 Architecture
 
 config AT32AP700X_WDT
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 53d4827ddfe1..e2bc52c79aa7 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -69,6 +69,7 @@ obj-$(CONFIG_MEDIATEK_WATCHDOG) += mtk_wdt.o
 obj-$(CONFIG_DIGICOLOR_WATCHDOG) += digicolor_wdt.o
 obj-$(CONFIG_LPC18XX_WATCHDOG) += lpc18xx_wdt.o
 obj-$(CONFIG_BCM7038_WDT) += bcm7038_wdt.o
+obj-$(CONFIG_ATLAS7_WATCHDOG) += atlas7_wdt.o
 
 # AVR32 Architecture
 obj-$(CONFIG_AT32AP700X_WDT) += at32ap700x_wdt.o
diff --git a/drivers/watchdog/atlas7_wdt.c b/drivers/watchdog/atlas7_wdt.c
new file mode 100644
index 000000000000..df6d9242a319
--- /dev/null
+++ b/drivers/watchdog/atlas7_wdt.c
@@ -0,0 +1,242 @@
+/*
+ * Watchdog driver for CSR Atlas7
+ *
+ * Copyright (c) 2015 Cambridge Silicon Radio Limited, a CSR plc group company.
+ *
+ * Licensed under GPLv2.
+ */
+
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/watchdog.h>
+
+#define ATLAS7_TIMER_WDT_INDEX          5
+#define ATLAS7_WDT_DEFAULT_TIMEOUT      20
+
+#define ATLAS7_WDT_CNT_CTRL     (0 + 4 * ATLAS7_TIMER_WDT_INDEX)
+#define ATLAS7_WDT_CNT_MATCH    (0x18 + 4 * ATLAS7_TIMER_WDT_INDEX)
+#define ATLAS7_WDT_CNT          (0x48 +  4 * ATLAS7_TIMER_WDT_INDEX)
+#define ATLAS7_WDT_CNT_EN       (BIT(0) | BIT(1))
+#define ATLAS7_WDT_EN           0x64
+
+static unsigned int timeout = ATLAS7_WDT_DEFAULT_TIMEOUT;
+static bool nowayout = WATCHDOG_NOWAYOUT;
+
+module_param(timeout, uint, 0);
+module_param(nowayout, bool, 0);
+
+MODULE_PARM_DESC(timeout, "Default watchdog timeout (in seconds)");
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
+                        __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+struct atlas7_wdog {
+        struct device *dev;
+        void __iomem *base;
+        unsigned long tick_rate;
+        struct clk *clk;
+};
+
+static unsigned int atlas7_wdt_gettimeleft(struct watchdog_device *wdd)
+{
+        struct atlas7_wdog *wdt = watchdog_get_drvdata(wdd);
+        u32 counter, match, delta;
+
+        counter = readl(wdt->base + ATLAS7_WDT_CNT);
+        match = readl(wdt->base + ATLAS7_WDT_CNT_MATCH);
+        delta = match - counter;
+
+        return  delta / wdt->tick_rate;
+}
+
+static int atlas7_wdt_ping(struct watchdog_device *wdd)
+{
+        struct atlas7_wdog *wdt = watchdog_get_drvdata(wdd);
+        u32 counter, match, delta;
+
+        counter = readl(wdt->base + ATLAS7_WDT_CNT);
+        delta = wdd->timeout * wdt->tick_rate;
+        match = counter + delta;
+
+        writel(match, wdt->base + ATLAS7_WDT_CNT_MATCH);
+
+        return 0;
+}
+
+static int atlas7_wdt_enable(struct watchdog_device *wdd)
+{
+        struct atlas7_wdog *wdt = watchdog_get_drvdata(wdd);
+
+        atlas7_wdt_ping(wdd);
+
+        writel(readl(wdt->base + ATLAS7_WDT_CNT_CTRL) | ATLAS7_WDT_CNT_EN,
+              wdt->base + ATLAS7_WDT_CNT_CTRL);
+        writel(1, wdt->base + ATLAS7_WDT_EN);
+
+        return 0;
+}
+
+static int atlas7_wdt_disable(struct watchdog_device *wdd)
+{
+        struct atlas7_wdog *wdt = watchdog_get_drvdata(wdd);
+
+        writel(0, wdt->base + ATLAS7_WDT_EN);
+        writel(readl(wdt->base + ATLAS7_WDT_CNT_CTRL) & ~ATLAS7_WDT_CNT_EN,
+              wdt->base + ATLAS7_WDT_CNT_CTRL);
+
+        return 0;
+}
+
+static int atlas7_wdt_settimeout(struct watchdog_device *wdd, unsigned int to)
+{
+        wdd->timeout = to;
+
+        return 0;
+}
+
+#define OPTIONS (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE)
+
+static const struct watchdog_info atlas7_wdt_ident = {
+        .options = OPTIONS,
+        .firmware_version = 0,
+        .identity = "atlas7 Watchdog",
+};
+
+static struct watchdog_ops atlas7_wdt_ops = {
+        .owner = THIS_MODULE,
+        .start = atlas7_wdt_enable,
+        .stop = atlas7_wdt_disable,
+        .get_timeleft = atlas7_wdt_gettimeleft,
+        .ping = atlas7_wdt_ping,
+        .set_timeout = atlas7_wdt_settimeout,
+};
+
+static struct watchdog_device atlas7_wdd = {
+        .info = &atlas7_wdt_ident,
+        .ops = &atlas7_wdt_ops,
+        .timeout = ATLAS7_WDT_DEFAULT_TIMEOUT,
+};
+
+static const struct of_device_id atlas7_wdt_ids[] = {
+        { .compatible = "sirf,atlas7-tick"},
+        {}
+};
+
+static int atlas7_wdt_probe(struct platform_device *pdev)
+{
+        struct device_node *np = pdev->dev.of_node;
+        struct atlas7_wdog *wdt;
+        struct resource *res;
+        struct clk *clk;
+        int ret;
+
+        wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
+        if (!wdt)
+                return -ENOMEM;
+        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+        wdt->base = devm_ioremap_resource(&pdev->dev, res);
+        if (IS_ERR(wdt->base))
+                return PTR_ERR(wdt->base);
+
+        clk = of_clk_get(np, 0);
+        if (IS_ERR(clk))
+                return PTR_ERR(clk);
+        ret = clk_prepare_enable(clk);
+        if (ret) {
+                dev_err(&pdev->dev, "clk enable failed\n");
+                goto err;
+        }
+
+        /* disable watchdog hardware */
+        writel(0, wdt->base + ATLAS7_WDT_CNT_CTRL);
+
+        wdt->tick_rate = clk_get_rate(clk);
+        wdt->clk = clk;
+        atlas7_wdd.min_timeout = 1;
+        atlas7_wdd.max_timeout = UINT_MAX / wdt->tick_rate;
+
+        watchdog_init_timeout(&atlas7_wdd, 0, &pdev->dev);
+        watchdog_set_nowayout(&atlas7_wdd, nowayout);
+
+        watchdog_set_drvdata(&atlas7_wdd, wdt);
+        platform_set_drvdata(pdev, &atlas7_wdd);
+
+        ret = watchdog_register_device(&atlas7_wdd);
+        if (ret)
+                goto err1;
+
+        return 0;
+
+err1:
+        clk_disable_unprepare(clk);
+err:
+        clk_put(clk);
+        return ret;
+}
+
+static void atlas7_wdt_shutdown(struct platform_device *pdev)
+{
+        struct watchdog_device *wdd = platform_get_drvdata(pdev);
+        struct atlas7_wdog *wdt = watchdog_get_drvdata(wdd);
+
+        atlas7_wdt_disable(wdd);
+        clk_disable_unprepare(wdt->clk);
+}
+
+static int atlas7_wdt_remove(struct platform_device *pdev)
+{
+        struct watchdog_device *wdd = platform_get_drvdata(pdev);
+        struct atlas7_wdog *wdt = watchdog_get_drvdata(wdd);
+
+        atlas7_wdt_shutdown(pdev);
+        clk_put(wdt->clk);
+        return 0;
+}
+
+static int __maybe_unused atlas7_wdt_suspend(struct device *dev)
+{
+        /*
+         * NOTE:timer controller registers settings are saved
+         * and restored back by the timer-atlas7.c
+         */
+        return 0;
+}
+
+static int __maybe_unused atlas7_wdt_resume(struct device *dev)
+{
+        struct watchdog_device *wdd = dev_get_drvdata(dev);
+
+        /*
+         * NOTE: Since timer controller registers settings are saved
+         * and restored back by the timer-atlas7.c, so we need not
+         * update WD settings except refreshing timeout.
+         */
+        atlas7_wdt_ping(wdd);
+
+        return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(atlas7_wdt_pm_ops,
+                atlas7_wdt_suspend, atlas7_wdt_resume);
+
+MODULE_DEVICE_TABLE(of, atlas7_wdt_ids);
+
+static struct platform_driver atlas7_wdt_driver = {
+        .driver = {
+                .name = "atlas7-wdt",
+                .pm = &atlas7_wdt_pm_ops,
+                .of_match_table = atlas7_wdt_ids,
+        },
+        .probe = atlas7_wdt_probe,
+        .remove = atlas7_wdt_remove,
+        .shutdown = atlas7_wdt_shutdown,
+};
+module_platform_driver(atlas7_wdt_driver);
+
+MODULE_DESCRIPTION("CSRatlas7 watchdog driver");
+MODULE_AUTHOR("Guo Zeng <Guo.Zeng@csr.com>");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:atlas7-wdt");