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>

diff --git a/Documentation/devicetree/bindings/pwm/vt8500-pwm.txt b/Documentation/devicetree/bindings/pwm/vt8500-pwm.txt
new file mode 100644 (file)
index 0000000..bcc6367
--- /dev/null
+++ b/Documentation/devicetree/bindings/pwm/vt8500-pwm.txt
@@ -0,0 +1,17 @@
+VIA/Wondermedia VT8500/WM8xxx series SoC PWM controller
+
+Required properties:
+- compatible: should be "via,vt8500-pwm"
+- reg: physical base address and length of the controller's registers
+- #pwm-cells: should be 2.  The first cell specifies the per-chip index
+  of the PWM to use and the second cell is the period in nanoseconds.
+- clocks: phandle to the PWM source clock
+
+Example:
+
+pwm1: pwm@d8220000 {
+       #pwm-cells = <2>;
+       compatible = "via,vt8500-pwm";
+       reg = <0xd8220000 0x1000>;
+       clocks = <&clkpwm>;
+};

diff --git a/drivers/pwm/pwm-vt8500.c b/drivers/pwm/pwm-vt8500.c
index ad14389b7144a29f142ed9b8e0c9d6df3b2793c0..970b0c6e268f7a1a715175bec805c7ecbbb13d54 100644 (file)
--- 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");