watchdog: at91sam9: get and use slow clock

Commit dca1a4b5ff6e ("clk: at91: keep slow clk enabled to prevent system
hang") added a workaround for the slow clock as it is not properly handled
by its users.

Get and use the slow clock as it is necessary for the at91sam9 watchdog.

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

diff --git a/drivers/watchdog/at91sam9_wdt.c b/drivers/watchdog/at91sam9_wdt.c
index e4698f7..7e6acaf 100644 (file)
--- a/drivers/watchdog/at91sam9_wdt.c
+++ b/drivers/watchdog/at91sam9_wdt.c
@@ -17,6 +17,7 @@
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
+#include <linux/clk.h>
 #include <linux/errno.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
@@ -90,6 +91,7 @@ struct at91wdt {
        unsigned long heartbeat;        /* WDT heartbeat in jiffies */
        bool nowayout;
        unsigned int irq;
+       struct clk *sclk;
 };
 
 /* ......................................................................... */
@@ -352,15 +354,25 @@ static int __init at91wdt_probe(struct platform_device *pdev)
        if (IS_ERR(wdt->base))
                return PTR_ERR(wdt->base);
 
+       wdt->sclk = devm_clk_get(&pdev->dev, NULL);
+       if (IS_ERR(wdt->sclk))
+               return PTR_ERR(wdt->sclk);
+
+       err = clk_prepare_enable(wdt->sclk);
+       if (err) {
+               dev_err(&pdev->dev, "Could not enable slow clock\n");
+               return err;
+       }
+
        if (pdev->dev.of_node) {
                err = of_at91wdt_init(pdev->dev.of_node, wdt);
                if (err)
-                       return err;
+                       goto err_clk;
        }
 
        err = at91_wdt_init(pdev, wdt);
        if (err)
-               return err;
+               goto err_clk;
 
        platform_set_drvdata(pdev, wdt);
 
@@ -368,6 +380,11 @@ static int __init at91wdt_probe(struct platform_device *pdev)
                wdt->wdd.timeout, wdt->nowayout);
 
        return 0;
+
+err_clk:
+       clk_disable_unprepare(wdt->sclk);
+
+       return err;
 }
 
 static int __exit at91wdt_remove(struct platform_device *pdev)
@@ -377,6 +394,7 @@ static int __exit at91wdt_remove(struct platform_device *pdev)
 
        pr_warn("I quit now, hardware will probably reboot!\n");
        del_timer(&wdt->timer);
+       clk_disable_unprepare(wdt->sclk);
 
        return 0;
 }