307 lines
6.8 KiB
C
307 lines
6.8 KiB
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.
|
|
*
|
|
* Derived from pxa PWM driver by eric miao <eric.miao@marvell.com>
|
|
*/
|
|
|
|
#include <linux/module.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/platform_device.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/err.h>
|
|
#include <linux/clk.h>
|
|
#include <linux/io.h>
|
|
#include <linux/pwm.h>
|
|
#include <mach/hardware.h>
|
|
|
|
|
|
/* i.MX1 and i.MX21 share the same PWM function block: */
|
|
|
|
#define MX1_PWMC 0x00 /* PWM Control Register */
|
|
#define MX1_PWMS 0x04 /* PWM Sample Register */
|
|
#define MX1_PWMP 0x08 /* PWM Period Register */
|
|
|
|
|
|
/* i.MX27, i.MX31, i.MX35 share the same PWM function block: */
|
|
|
|
#define MX3_PWMCR 0x00 /* PWM Control Register */
|
|
#define MX3_PWMSAR 0x0C /* PWM Sample Register */
|
|
#define MX3_PWMPR 0x10 /* PWM Period Register */
|
|
#define MX3_PWMCR_PRESCALER(x) (((x - 1) & 0xFFF) << 4)
|
|
#define MX3_PWMCR_DOZEEN (1 << 24)
|
|
#define MX3_PWMCR_WAITEN (1 << 23)
|
|
#define MX3_PWMCR_DBGEN (1 << 22)
|
|
#define MX3_PWMCR_CLKSRC_IPG_HIGH (2 << 16)
|
|
#define MX3_PWMCR_CLKSRC_IPG (1 << 16)
|
|
#define MX3_PWMCR_EN (1 << 0)
|
|
|
|
|
|
|
|
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;
|
|
};
|
|
|
|
int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
|
|
{
|
|
if (pwm == NULL || period_ns == 0 || duty_ns > period_ns)
|
|
return -EINVAL;
|
|
|
|
if (!(cpu_is_mx1() || cpu_is_mx21())) {
|
|
unsigned long long c;
|
|
unsigned long period_cycles, duty_cycles, prescale;
|
|
u32 cr;
|
|
|
|
c = clk_get_rate(pwm->clk);
|
|
c = c * period_ns;
|
|
do_div(c, 1000000000);
|
|
period_cycles = c;
|
|
|
|
prescale = period_cycles / 0x10000 + 1;
|
|
|
|
period_cycles /= prescale;
|
|
c = (unsigned long long)period_cycles * duty_ns;
|
|
do_div(c, period_ns);
|
|
duty_cycles = c;
|
|
|
|
/*
|
|
* according to imx pwm RM, the real period value should be
|
|
* PERIOD value in PWMPR plus 2.
|
|
*/
|
|
if (period_cycles > 2)
|
|
period_cycles -= 2;
|
|
else
|
|
period_cycles = 0;
|
|
|
|
writel(duty_cycles, pwm->mmio_base + MX3_PWMSAR);
|
|
writel(period_cycles, pwm->mmio_base + MX3_PWMPR);
|
|
|
|
cr = MX3_PWMCR_PRESCALER(prescale) |
|
|
MX3_PWMCR_DOZEEN | MX3_PWMCR_WAITEN |
|
|
MX3_PWMCR_DBGEN | MX3_PWMCR_EN;
|
|
|
|
if (cpu_is_mx25())
|
|
cr |= MX3_PWMCR_CLKSRC_IPG;
|
|
else
|
|
cr |= MX3_PWMCR_CLKSRC_IPG_HIGH;
|
|
|
|
writel(cr, pwm->mmio_base + MX3_PWMCR);
|
|
} else if (cpu_is_mx1() || cpu_is_mx21()) {
|
|
/* The PWM subsystem allows for exact frequencies. However,
|
|
* I cannot connect a scope on my device to the PWM line and
|
|
* thus cannot provide the program the PWM controller
|
|
* exactly. Instead, I'm relying on the fact that the
|
|
* Bootloader (u-boot or WinCE+haret) has programmed the PWM
|
|
* function group already. So I'll just modify the PWM sample
|
|
* register to follow the ratio of duty_ns vs. period_ns
|
|
* accordingly.
|
|
*
|
|
* This is good enough for programming the brightness of
|
|
* the LCD backlight.
|
|
*
|
|
* The real implementation would divide PERCLK[0] first by
|
|
* both the prescaler (/1 .. /128) and then by CLKSEL
|
|
* (/2 .. /16).
|
|
*/
|
|
u32 max = readl(pwm->mmio_base + MX1_PWMP);
|
|
u32 p = max * duty_ns / period_ns;
|
|
writel(max - p, pwm->mmio_base + MX1_PWMS);
|
|
} else {
|
|
BUG();
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(pwm_config);
|
|
|
|
int pwm_enable(struct pwm_device *pwm)
|
|
{
|
|
int rc = 0;
|
|
|
|
if (!pwm->clk_enabled) {
|
|
rc = clk_prepare_enable(pwm->clk);
|
|
if (!rc)
|
|
pwm->clk_enabled = 1;
|
|
}
|
|
return rc;
|
|
}
|
|
EXPORT_SYMBOL(pwm_enable);
|
|
|
|
void pwm_disable(struct pwm_device *pwm)
|
|
{
|
|
writel(0, pwm->mmio_base + MX3_PWMCR);
|
|
|
|
if (pwm->clk_enabled) {
|
|
clk_disable_unprepare(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 int __devinit mxc_pwm_probe(struct platform_device *pdev)
|
|
{
|
|
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 -ENOMEM;
|
|
}
|
|
|
|
pwm->clk = clk_get(&pdev->dev, "pwm");
|
|
|
|
if (IS_ERR(pwm->clk)) {
|
|
ret = PTR_ERR(pwm->clk);
|
|
goto err_free;
|
|
}
|
|
|
|
pwm->clk_enabled = 0;
|
|
|
|
pwm->use_count = 0;
|
|
pwm->pwm_id = pdev->id;
|
|
pwm->pdev = pdev;
|
|
|
|
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, resource_size(r), 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, resource_size(r));
|
|
if (pwm->mmio_base == NULL) {
|
|
dev_err(&pdev->dev, "failed to ioremap() registers\n");
|
|
ret = -ENODEV;
|
|
goto err_free_mem;
|
|
}
|
|
|
|
mutex_lock(&pwm_lock);
|
|
list_add_tail(&pwm->node, &pwm_list);
|
|
mutex_unlock(&pwm_lock);
|
|
|
|
platform_set_drvdata(pdev, pwm);
|
|
return 0;
|
|
|
|
err_free_mem:
|
|
release_mem_region(r->start, resource_size(r));
|
|
err_free_clk:
|
|
clk_put(pwm->clk);
|
|
err_free:
|
|
kfree(pwm);
|
|
return ret;
|
|
}
|
|
|
|
static int __devexit mxc_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, resource_size(r));
|
|
|
|
clk_put(pwm->clk);
|
|
|
|
kfree(pwm);
|
|
return 0;
|
|
}
|
|
|
|
static struct platform_driver mxc_pwm_driver = {
|
|
.driver = {
|
|
.name = "mxc_pwm",
|
|
},
|
|
.probe = mxc_pwm_probe,
|
|
.remove = __devexit_p(mxc_pwm_remove),
|
|
};
|
|
|
|
static int __init mxc_pwm_init(void)
|
|
{
|
|
return platform_driver_register(&mxc_pwm_driver);
|
|
}
|
|
arch_initcall(mxc_pwm_init);
|
|
|
|
static void __exit mxc_pwm_exit(void)
|
|
{
|
|
platform_driver_unregister(&mxc_pwm_driver);
|
|
}
|
|
module_exit(mxc_pwm_exit);
|
|
|
|
MODULE_LICENSE("GPL v2");
|
|
MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>");
|