/*
* linux/arch/arm/mach-pxa/pwm.c
*
* simple driver for PWM (Pulse Width Modulator) controller
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* 2008-02-13 initial version
* eric miao <eric.miao@marvell.com>
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/pwm.h>
#include <asm/div64.h>
/* PWM registers and bits definitions */
#define PWMCR (0x00)
#define PWMDCR (0x04)
#define PWMPCR (0x08)
#define PWMCR_SD (1 << 6)
#define PWMDCR_FD (1 << 10)
struct pwm_device {
struct list_head node;
struct platform_device *pdev;
const char *label;
struct clk *clk;
int clk_enabled;
void __iomem *mmio_base;
unsigned int use_count;
unsigned int pwm_id;
};
/*
* period_ns = 10^9 * (PRESCALE + 1) * (PV + 1) / PWM_CLK_RATE
* duty_ns = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
*/
int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
{
unsigned long long c;
unsigned long period_cycles, prescale, pv, dc;
if (pwm == NULL || period_ns == 0 || duty_ns > period_ns)
return -EINVAL;
c = clk_get_rate(pwm->clk);
c = c * period_ns;
do_div(c, 1000000000);
period_cycles = c;
if (period_cycles < 1)
period_cycles = 1;
prescale = (period_cycles - 1) / 1024;
pv = period_cycles / (prescale + 1) - 1;
if (prescale > 63)
return -EINVAL;
if (duty_ns == period_ns)
dc = PWMDCR_FD;
else
dc = (pv + 1) * duty_ns / period_ns;
/* NOTE: the clock to PWM has to be enabled first
* before writing to the registers
*/
clk_enable(pwm->clk);
__raw_writel(prescale, pwm->mmio_base + PWMCR);
__raw_writel(dc, pwm->mmio_base + PWMDCR);
__raw_writel(pv, pwm->mmio_base + PWMPCR);
clk_disable(pwm->clk);
return 0;
}
EXPORT_SYMBOL(pwm_config);
int pwm_enable(struct pwm_device *pwm)
{
int rc = 0;
if (!pwm->clk_enabled) {
rc = clk_enable(pwm->clk);
if (!rc)
pwm->clk_enabled = 1;
}
return rc;
}
EXPORT_SYMBOL(pwm_enable);
void pwm_disable(struct pwm_device *pwm)
{
if (pwm->clk_enabled) {
clk_disable(pwm->clk);
pwm->clk_enabled = 0;
}
}
EXPORT_SYMBOL(pwm_disable);
static DEFINE_MUTEX(pwm_lock);
static LIST_HEAD(pwm_list);
struct pwm_device *pwm_request(int pwm_id, const char *label)
{
struct pwm_device *pwm;
int found = 0;
mutex_lock(&pwm_lock);
list_for_each_entry(pwm, &pwm_list, node) {
if (pwm->pwm_id == pwm_id) {
found = 1;
break;
}
}
if (found) {
if (pwm->use_count == 0) {
pwm->use_count++;
pwm->label = label;
} else
pwm = ERR_PTR(-EBUSY);
} else
pwm = ERR_PTR(-ENOENT);
mutex_unlock(&pwm_lock);
return pwm;
}
EXPORT_SYMBOL(pwm_request);
void pwm_free(struct pwm_device *pwm)
{
mutex_lock(&pwm_lock);
if (pwm->use_count) {
pwm->use_count--;
pwm->label = NULL;
} else
pr_warning("PWM device already freed\n");
mutex_unlock(&pwm_lock);
}
EXPORT_SYMBOL(pwm_free);
static inline void __add_pwm(struct pwm_device *pwm)
{
mutex_lock(&pwm_lock);
list_add_tail(&pwm->node, &pwm_list);
mutex_unlock(&pwm_lock);
}
static struct pwm_device *pwm_probe(struct platform_device *pdev,
unsigned int pwm_id, struct pwm_device *parent_pwm)
{
struct pwm_device *pwm;
struct resource *r;
int ret = 0;
pwm = kzalloc(sizeof(struct pwm_device), GFP_KERNEL);
if (pwm == NULL) {
dev_err(&pdev->dev, "failed to allocate memory\n");
return ERR_PTR(-ENOMEM);
}
pwm->clk = clk_get(&pdev->dev, NULL);
if (IS_ERR(pwm->clk)) {
ret = PTR_ERR(pwm->clk);
goto err_free;
}
pwm->clk_enabled = 0;
pwm->use_count = 0;
pwm->pwm_id = pwm_id;
pwm->pdev = pdev;
if (parent_pwm != NULL) {
/* registers for the second PWM has offset of 0x10 */
pwm->mmio_base = parent_pwm->mmio_base + 0x10;
__add_pwm(pwm);
return pwm;
}
r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (r == NULL) {
dev_err(&pdev->dev, "no memory resource defined\n");
ret = -ENODEV;
goto err_free_clk;
}
r = request_mem_region(r->start, r->end - r->start + 1, pdev->name);
if (r == NULL) {
dev_err(&pdev->dev, "failed to request memory resource\n");
ret = -EBUSY;
goto err_free_clk;
}
pwm->mmio_base = ioremap(r->start, r->end - r->start + 1);
if (pwm->mmio_base == NULL) {
dev_err(&pdev->dev, "failed to ioremap() registers\n");
ret = -ENODEV;
goto err_free_mem;
}
__add_pwm(pwm);
platform_set_drvdata(pdev, pwm);
return pwm;
err_free_mem:
release_mem_region(r->start, r->end - r->start + 1);
err_free_clk:
clk_put(pwm->clk);
err_free:
kfree(pwm);
return ERR_PTR(ret);
}
static int __devinit pxa25x_pwm_probe(struct platform_device *pdev)
{
struct pwm_device *pwm = pwm_probe(pdev, pdev->id, NULL);
if (IS_ERR(pwm))
return PTR_ERR(pwm);
return 0;
}
static int __devinit pxa27x_pwm_probe(struct platform_device *pdev)
{
struct pwm_device *pwm;
pwm = pwm_probe(pdev, pdev->id, NULL);
if (IS_ERR(pwm))
return PTR_ERR(pwm);
pwm = pwm_probe(pdev, pdev->id + 2, pwm);
if (IS_ERR(pwm))
return PTR_ERR(pwm);
return 0;
}
static int __devexit pwm_remove(struct platform_device *pdev)
{
struct pwm_device *pwm;
struct resource *r;
pwm = platform_get_drvdata(pdev);
if (pwm == NULL)
return -ENODEV;
mutex_lock(&pwm_lock);
list_del(&pwm->node);
mutex_unlock(&pwm_lock);
iounmap(pwm->mmio_base);
r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
release_mem_region(r->start, r->end - r->start + 1);
clk_put(pwm->clk);
kfree(pwm);
return 0;
}
static struct platform_driver pxa25x_pwm_driver = {
.driver = {
.name = "pxa25x-pwm",
},
.probe = pxa25x_pwm_probe,
.remove = __devexit_p(pwm_remove),
};
static struct platform_driver pxa27x_pwm_driver = {
.driver = {
.name = "pxa27x-pwm",
},
.probe = pxa27x_pwm_probe,
.remove = __devexit_p(pwm_remove),
};
static int __init pwm_init(void)
{
int ret = 0;
ret = platform_driver_register(&pxa25x_pwm_driver);
if (ret) {
printk(KERN_ERR "failed to register pxa25x_pwm_driver\n");
return ret;
}
ret = platform_driver_register(&pxa27x_pwm_driver);
if (ret) {
printk(KERN_ERR "failed to register pxa27x_pwm_driver\n");
return ret;
}
return ret;
}
arch_initcall(pwm_init);
static void __exit pwm_exit(void)
{
platform_driver_unregister(&pxa25x_pwm_driver);
platform_driver_unregister(&pxa27x_pwm_driver);
}
module_exit(pwm_exit);
MODULE_LICENSE("GPL v2");
