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pwm: vt8500: Update vt8500 PWM driver support

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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>
This commit is contained in:
Tony Prisk 2012-10-27 14:49:57 +13:00 committed by Thierry Reding
parent 8f0d8163b5
commit 63e1ed2364
2 changed files with 81 additions and 24 deletions
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17
Documentation/devicetree/bindings/pwm/vt8500-pwm.txt Normal file
View file

@ -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>;
};

88
drivers/pwm/pwm-vt8500.c
View file

@ -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 = pwmchip_add(&chip->chip);
if (ret < 0)
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) {
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");