watchdog: npcm: Enable clock if provided

On the Nuvoton WPCM450 SoC, with its upcoming clock driver, peripheral
clocks are individually gated and ungated. Therefore, the watchdog
driver must be able to ungate the watchdog clock.

Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20220610072141.347795-3-j.neuschaefer@gmx.net
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

diff --git a/drivers/watchdog/npcm_wdt.c b/drivers/watchdog/npcm_wdt.c
index 28a24caa2627c924416ef628cc548fa6383d2da2..a5dd1c2301374402ae4d28265798438ddd8cba34 100644 (file)
--- a/drivers/watchdog/npcm_wdt.c
+++ b/drivers/watchdog/npcm_wdt.c
@@ -3,6 +3,7 @@
 // Copyright (c) 2018 IBM Corp.
 
 #include <linux/bitops.h>
+#include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/interrupt.h>
 #include <linux/kernel.h>
@@ -43,6 +44,7 @@
 struct npcm_wdt {
        struct watchdog_device  wdd;
        void __iomem            *reg;
+       struct clk              *clk;
 };
 
 static inline struct npcm_wdt *to_npcm_wdt(struct watchdog_device *wdd)
@@ -66,6 +68,9 @@ static int npcm_wdt_start(struct watchdog_device *wdd)
        struct npcm_wdt *wdt = to_npcm_wdt(wdd);
        u32 val;
 
+       if (wdt->clk)
+               clk_prepare_enable(wdt->clk);
+
        if (wdd->timeout < 2)
                val = 0x800;
        else if (wdd->timeout < 3)
@@ -100,6 +105,9 @@ static int npcm_wdt_stop(struct watchdog_device *wdd)
 
        writel(0, wdt->reg);
 
+       if (wdt->clk)
+               clk_disable_unprepare(wdt->clk);
+
        return 0;
 }
 
@@ -147,6 +155,10 @@ static int npcm_wdt_restart(struct watchdog_device *wdd,
 {
        struct npcm_wdt *wdt = to_npcm_wdt(wdd);
 
+       /* For reset, we start the WDT clock and leave it running. */
+       if (wdt->clk)
+               clk_prepare_enable(wdt->clk);
+
        writel(NPCM_WTR | NPCM_WTRE | NPCM_WTE, wdt->reg);
        udelay(1000);
 
@@ -191,6 +203,10 @@ static int npcm_wdt_probe(struct platform_device *pdev)
        if (IS_ERR(wdt->reg))
                return PTR_ERR(wdt->reg);
 
+       wdt->clk = devm_clk_get_optional(&pdev->dev, NULL);
+       if (IS_ERR(wdt->clk))
+               return PTR_ERR(wdt->clk);
+
        irq = platform_get_irq(pdev, 0);
        if (irq < 0)
                return irq;