linux-kernel - [PATCH 2/4] watchdog: coh901327_wdt: Keep clock enabled after loading driver

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Date:   Tue,  3 Jan 2017 19:25:41 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Linus Walleij <linus.walleij@...aro.org>
Cc:     Wim Van Sebroeck <wim@...ana.be>,
        linux-arm-kernel@...ts.infradead.org,
        linux-watchdog@...r.kernel.org, linux-kernel@...r.kernel.org,
        Guenter Roeck <linux@...ck-us.net>
Subject: [PATCH 2/4] watchdog: coh901327_wdt: Keep clock enabled after loading driver

Enabling the clock before accessing chip registers and disabling it
afterwards does not really make sense and only adds complexity to
the driver. In addition to that, a comment int the driver suggests
that it does not serve a useful purpose either.

"The watchdog block is of course always clocked, the
 clk_enable()/clk_disable() calls are mainly for performing reference
 counting higher up in the clock hierarchy."

Just keep the clock enabled instead.

Signed-off-by: Guenter Roeck <linux@...ck-us.net>
---
 drivers/watchdog/coh901327_wdt.c | 21 +--------------------
 1 file changed, 1 insertion(+), 20 deletions(-)

diff --git a/drivers/watchdog/coh901327_wdt.c b/drivers/watchdog/coh901327_wdt.c
index dc97b2fd6c49..1385a920df4f 100644
--- a/drivers/watchdog/coh901327_wdt.c
+++ b/drivers/watchdog/coh901327_wdt.c
@@ -74,11 +74,6 @@ static int irq;
 static void __iomem *virtbase;
 static struct device *parent;
 
-/*
- * The watchdog block is of course always clocked, the
- * clk_enable()/clk_disable() calls are mainly for performing reference
- * counting higher up in the clock hierarchy.
- */
 static struct clk *clk;
 
 /*
@@ -90,7 +85,6 @@ static void coh901327_enable(u16 timeout)
 	unsigned long freq;
 	unsigned long delay_ns;
 
-	clk_enable(clk);
 	/* Restart timer if it is disabled */
 	val = readw(virtbase + U300_WDOG_D2R);
 	if (val == U300_WDOG_D2R_DISABLE_STATUS_DISABLED)
@@ -118,7 +112,6 @@ static void coh901327_enable(u16 timeout)
 	 */
 	(void) readw(virtbase + U300_WDOG_CR);
 	val = readw(virtbase + U300_WDOG_D2R);
-	clk_disable(clk);
 	if (val != U300_WDOG_D2R_DISABLE_STATUS_ENABLED)
 		dev_err(parent,
 			"%s(): watchdog not enabled! D2R value %04x\n",
@@ -129,7 +122,6 @@ static void coh901327_disable(void)
 {
 	u16 val;
 
-	clk_enable(clk);
 	/* Disable the watchdog interrupt if it is active */
 	writew(0x0000U, virtbase + U300_WDOG_IMR);
 	/* If the watchdog is currently enabled, attempt to disable it */
@@ -144,7 +136,6 @@ static void coh901327_disable(void)
 		       virtbase + U300_WDOG_D2R);
 	}
 	val = readw(virtbase + U300_WDOG_D2R);
-	clk_disable(clk);
 	if (val != U300_WDOG_D2R_DISABLE_STATUS_DISABLED)
 		dev_err(parent,
 			"%s(): watchdog not disabled! D2R value %04x\n",
@@ -165,11 +156,9 @@ static int coh901327_stop(struct watchdog_device *wdt_dev)
 
 static int coh901327_ping(struct watchdog_device *wdd)
 {
-	clk_enable(clk);
 	/* Feed the watchdog */
 	writew(U300_WDOG_FR_FEED_RESTART_TIMER,
 	       virtbase + U300_WDOG_FR);
-	clk_disable(clk);
 	return 0;
 }
 
@@ -177,13 +166,11 @@ static int coh901327_settimeout(struct watchdog_device *wdt_dev,
 				unsigned int time)
 {
 	wdt_dev->timeout = time;
-	clk_enable(clk);
 	/* Set new timeout value */
 	writew(time * 100, virtbase + U300_WDOG_TR);
 	/* Feed the dog */
 	writew(U300_WDOG_FR_FEED_RESTART_TIMER,
 	       virtbase + U300_WDOG_FR);
-	clk_disable(clk);
 	return 0;
 }
 
@@ -191,13 +178,11 @@ static unsigned int coh901327_gettimeleft(struct watchdog_device *wdt_dev)
 {
 	u16 val;
 
-	clk_enable(clk);
 	/* Read repeatedly until the value is stable! */
 	val = readw(virtbase + U300_WDOG_CR);
 	while (val & U300_WDOG_CR_VALID_IND)
 		val = readw(virtbase + U300_WDOG_CR);
 	val &= U300_WDOG_CR_COUNT_VALUE_MASK;
-	clk_disable(clk);
 	if (val != 0)
 		val /= 100;
 
@@ -221,13 +206,11 @@ static irqreturn_t coh901327_interrupt(int irq, void *data)
 	 * to prevent a watchdog reset by feeding the watchdog at this
 	 * point.
 	 */
-	clk_enable(clk);
 	val = readw(virtbase + U300_WDOG_IER);
 	if (val == U300_WDOG_IER_WILL_BARK_IRQ_EVENT_IND)
 		writew(U300_WDOG_IER_WILL_BARK_IRQ_ACK_ENABLE,
 		       virtbase + U300_WDOG_IER);
 	writew(0x0000U, virtbase + U300_WDOG_IMR);
-	clk_disable(clk);
 	dev_crit(parent, "watchdog is barking!\n");
 	return IRQ_HANDLED;
 }
@@ -263,7 +246,7 @@ static int __exit coh901327_remove(struct platform_device *pdev)
 	watchdog_unregister_device(&coh901327_wdt);
 	coh901327_disable();
 	free_irq(irq, pdev);
-	clk_unprepare(clk);
+	clk_disable_unprepare(clk);
 	clk_put(clk);
 	iounmap(virtbase);
 	release_mem_region(phybase, physize);
@@ -352,8 +335,6 @@ static int __init coh901327_probe(struct platform_device *pdev)
 		goto out_no_irq;
 	}
 
-	clk_disable(clk);
-
 	ret = watchdog_init_timeout(&coh901327_wdt, margin, &pdev->dev);
 	if (ret < 0)
 		coh901327_wdt.timeout = 60;
-- 
2.7.4