pwm: vt8500: Update vt8500 PWM driver support

This patch updates pwm-vt8500.c to support devicetree probing and
make use of the common clock subsystem.

A binding document describing the PWM controller found on
arch-vt8500 is also included.

Signed-off-by: Tony Prisk <linux@prisktech.co.nz>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>

1 files changed, 63 insertions, 23 deletions

diff --git a/drivers/pwm/pwm-vt8500.c b/drivers/pwm/pwm-vt8500.c
index ad14389b714..970b0c6e268 100644
--- a/drivers/pwm/pwm-vt8500.c
+++ b/drivers/pwm/pwm-vt8500.c
@@ -1,7 +1,8 @@
 /*
  * drivers/pwm/pwm-vt8500.c
  *
- *  Copyright (C) 2010 Alexey Charkov <alchark@gmail.com>
+ * Copyright (C) 2012 Tony Prisk <linux@prisktech.co.nz>
+ * Copyright (C) 2010 Alexey Charkov <alchark@gmail.com>
  *
  * This software is licensed under the terms of the GNU General Public
  * License version 2, as published by the Free Software Foundation, and
@@ -21,14 +22,24 @@
 #include <linux/io.h>
 #include <linux/pwm.h>
 #include <linux/delay.h>
+#include <linux/clk.h>
 
 #include <asm/div64.h>
 
-#define VT8500_NR_PWMS 4
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/of_address.h>
+
+/*
+ * SoC architecture allocates register space for 4 PWMs but only
+ * 2 are currently implemented.
+ */
+#define VT8500_NR_PWMS  2
 
 struct vt8500_chip {
         struct pwm_chip chip;
         void __iomem *base;
+        struct clk *clk;
 };
 
 #define to_vt8500_chip(chip)    container_of(chip, struct vt8500_chip, chip)
@@ -52,7 +63,7 @@ static int vt8500_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
         unsigned long long c;
         unsigned long period_cycles, prescale, pv, dc;
 
-        c = 25000000/2; /* wild guess --- need to implement clocks */
+        c = clk_get_rate(vt8500->clk);
         c = c * period_ns;
         do_div(c, 1000000000);
         period_cycles = c;
@@ -85,8 +96,15 @@ static int vt8500_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 
 static int vt8500_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 {
+        int err;
         struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
 
+        err = clk_enable(vt8500->clk);
+        if (err < 0)
+                dev_err(chip->dev, "failed to enable clock\n");
+                return err;
+        };
+
         pwm_busy_wait(vt8500->base + 0x40 + pwm->hwpwm, (1 << 0));
         writel(5, vt8500->base + (pwm->hwpwm << 4));
         return 0;
@@ -98,6 +116,8 @@ static void vt8500_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 
         pwm_busy_wait(vt8500->base + 0x40 + pwm->hwpwm, (1 << 0));
         writel(0, vt8500->base + (pwm->hwpwm << 4));
+
+        clk_disable(vt8500->clk);
 }
 
 static struct pwm_ops vt8500_pwm_ops = {
@@ -107,12 +127,24 @@ static struct pwm_ops vt8500_pwm_ops = {
         .owner = THIS_MODULE,
 };
 
-static int __devinit pwm_probe(struct platform_device *pdev)
+static const struct of_device_id vt8500_pwm_dt_ids[] = {
+        { .compatible = "via,vt8500-pwm", },
+        { /* Sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, vt8500_pwm_dt_ids);
+
+static int vt8500_pwm_probe(struct platform_device *pdev)
 {
         struct vt8500_chip *chip;
         struct resource *r;
+        struct device_node *np = pdev->dev.of_node;
         int ret;
 
+        if (!np) {
+                dev_err(&pdev->dev, "invalid devicetree node\n");
+                return -EINVAL;
+        }
+
         chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
         if (chip == NULL) {
                 dev_err(&pdev->dev, "failed to allocate memory\n");
@@ -124,6 +156,12 @@ static int __devinit pwm_probe(struct platform_device *pdev)
         chip->chip.base = -1;
         chip->chip.npwm = VT8500_NR_PWMS;
 
+        chip->clk = devm_clk_get(&pdev->dev, NULL);
+        if (IS_ERR(chip->clk)) {
+                dev_err(&pdev->dev, "clock source not specified\n");
+                return PTR_ERR(chip->clk);
+        }
+
         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
         if (r == NULL) {
                 dev_err(&pdev->dev, "no memory resource defined\n");
@@ -131,18 +169,26 @@ static int __devinit pwm_probe(struct platform_device *pdev)
         }
 
         chip->base = devm_request_and_ioremap(&pdev->dev, r);
-        if (chip->base == NULL)
+        if (!chip->base)
                 return -EADDRNOTAVAIL;
 
+        ret = clk_prepare(chip->clk);
+        if (ret < 0) {
+                dev_err(&pdev->dev, "failed to prepare clock\n");
+                return ret;
+        }
+
         ret = pwmchip_add(&chip->chip);
-        if (ret < 0)
+        if (ret < 0) {
+                dev_err(&pdev->dev, "failed to add PWM chip\n");
                 return ret;
+        }
 
         platform_set_drvdata(pdev, chip);
         return ret;
 }
 
-static int __devexit pwm_remove(struct platform_device *pdev)
+static int vt8500_pwm_remove(struct platform_device *pdev)
 {
         struct vt8500_chip *chip;
 
@@ -150,28 +196,22 @@ static int __devexit pwm_remove(struct platform_device *pdev)
         if (chip == NULL)
                 return -ENODEV;
 
+        clk_unprepare(chip->clk);
+
         return pwmchip_remove(&chip->chip);
 }
 
-static struct platform_driver pwm_driver = {
+static struct platform_driver vt8500_pwm_driver = {
+        .probe          = vt8500_pwm_probe,
+        .remove         = vt8500_pwm_remove,
         .driver         = {
                 .name   = "vt8500-pwm",
                 .owner  = THIS_MODULE,
+                .of_match_table = vt8500_pwm_dt_ids,
         },
-        .probe          = pwm_probe,
-        .remove         = __devexit_p(pwm_remove),
 };
+module_platform_driver(vt8500_pwm_driver);
 
-static int __init pwm_init(void)
-{
-        return platform_driver_register(&pwm_driver);
-}
-arch_initcall(pwm_init);
-
-static void __exit pwm_exit(void)
-{
-        platform_driver_unregister(&pwm_driver);
-}
-module_exit(pwm_exit);
-
-MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("VT8500 PWM Driver");
+MODULE_AUTHOR("Tony Prisk <linux@prisktech.co.nz>");
+MODULE_LICENSE("GPL v2");