linux-kernel - [PATCH 1/6] unicore32: pwm: Properly remap memory-mapped registers

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Date:	Sun,  2 Sep 2012 12:21:08 +0200
From:	Thierry Reding <thierry.reding@...onic-design.de>
To:	Guan Xuetao <gxt@...c.pku.edu.cn>
Cc:	Mike Turquette <mturquette@...aro.org>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 1/6] unicore32: pwm: Properly remap memory-mapped registers

Instead of writing to the timer controller registers by dereferencing a
pointer to the memory location, properly remap the memory region with a
call to ioremap_nocache() and access the registers using writel().

Signed-off-by: Thierry Reding <thierry.reding@...onic-design.de>
---
 arch/unicore32/kernel/pwm.c | 25 ++++++++++++++++++++++---
 1 file changed, 22 insertions(+), 3 deletions(-)

diff --git a/arch/unicore32/kernel/pwm.c b/arch/unicore32/kernel/pwm.c
index 4615d51..410b786 100644
--- a/arch/unicore32/kernel/pwm.c
+++ b/arch/unicore32/kernel/pwm.c
@@ -23,10 +23,16 @@
 #include <asm/div64.h>
 #include <mach/hardware.h>
 
+#define PWCR 0x00
+#define DCCR 0x04
+#define PCR  0x08
+
 struct pwm_device {
 	struct list_head	node;
 	struct platform_device *pdev;
 
+	void __iomem	*base;
+
 	const char	*label;
 	struct clk	*clk;
 	int		clk_enabled;
@@ -69,9 +75,11 @@ int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
 	 * before writing to the registers
 	 */
 	clk_enable(pwm->clk);
-	OST_PWMPWCR = prescale;
-	OST_PWMDCCR = pv - dc;
-	OST_PWMPCR  = pv;
+
+	writel(prescale, pwm->base + PWCR);
+	writel(pv - dc, pwm->base + DCCR);
+	writel(pv, pwm->base + PCR);
+
 	clk_disable(pwm->clk);
 
 	return 0;
@@ -190,10 +198,19 @@ static struct pwm_device *pwm_probe(struct platform_device *pdev,
 		goto err_free_clk;
 	}
 
+	pwm->base = ioremap_nocache(r->start, resource_size(r));
+	if (pwm->base == NULL) {
+		dev_err(&pdev->dev, "failed to remap memory resource\n");
+		ret = -EADDRNOTAVAIL;
+		goto err_release_mem;
+	}
+
 	__add_pwm(pwm);
 	platform_set_drvdata(pdev, pwm);
 	return pwm;
 
+err_release_mem:
+	release_mem_region(r->start, resource_size(r));
 err_free_clk:
 	clk_put(pwm->clk);
 err_free:
@@ -224,6 +241,8 @@ static int __devexit pwm_remove(struct platform_device *pdev)
 	list_del(&pwm->node);
 	mutex_unlock(&pwm_lock);
 
+	iounmap(pwm->base);
+
 	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	release_mem_region(r->start, resource_size(r));
 
-- 
1.7.12

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