watchdog: renesas_wdt: support handover from bootloader

Support an already running watchdog by checking its enable bit and set
up the status accordingly before registering the device.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20200908095615.31376-1-wsa+renesas@sang-engineering.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

diff --git a/drivers/watchdog/renesas_wdt.c b/drivers/watchdog/renesas_wdt.c
index 00662a8e039ccd2ac67ab8bd5751ff5863756039..47fce4de01105556429ee1f15c592bc1aeb7c922 100644 (file)
--- a/drivers/watchdog/renesas_wdt.c
+++ b/drivers/watchdog/renesas_wdt.c
@@ -194,6 +194,7 @@ static int rwdt_probe(struct platform_device *pdev)
        struct clk *clk;
        unsigned long clks_per_sec;
        int ret, i;
+       u8 csra;
 
        if (rwdt_blacklisted(dev))
                return -ENODEV;
@@ -213,8 +214,8 @@ static int rwdt_probe(struct platform_device *pdev)
        pm_runtime_enable(dev);
        pm_runtime_get_sync(dev);
        priv->clk_rate = clk_get_rate(clk);
-       priv->wdev.bootstatus = (readb_relaxed(priv->base + RWTCSRA) &
-                               RWTCSRA_WOVF) ? WDIOF_CARDRESET : 0;
+       csra = readb_relaxed(priv->base + RWTCSRA);
+       priv->wdev.bootstatus = csra & RWTCSRA_WOVF ? WDIOF_CARDRESET : 0;
        pm_runtime_put(dev);
 
        if (!priv->clk_rate) {
@@ -252,6 +253,13 @@ static int rwdt_probe(struct platform_device *pdev)
        /* This overrides the default timeout only if DT configuration was found */
        watchdog_init_timeout(&priv->wdev, 0, dev);
 
+       /* Check if FW enabled the watchdog */
+       if (csra & RWTCSRA_TME) {
+               /* Ensure properly initialized dividers */
+               rwdt_start(&priv->wdev);
+               set_bit(WDOG_HW_RUNNING, &priv->wdev.status);
+       }
+
        ret = watchdog_register_device(&priv->wdev);
        if (ret < 0)
                goto out_pm_disable;