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linux-sg2042/drivers/pwm/pwm-samsung.c

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/* drivers/pwm/pwm-samsung.c
*
* Copyright (c) 2007 Ben Dooks
* Copyright (c) 2008 Simtec Electronics
* Ben Dooks <ben@simtec.co.uk>, <ben-linux@fluff.org>
*
* S3C series PWM device core
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License.
*/
#define pr_fmt(fmt) "pwm-samsung: " fmt
#include <linux/export.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/map.h>
#include <plat/regs-timer.h>
struct s3c_chip {
struct platform_device *pdev;
struct clk *clk_div;
struct clk *clk;
const char *label;
unsigned int period_ns;
unsigned int duty_ns;
unsigned char tcon_base;
unsigned char pwm_id;
struct pwm_chip chip;
};
#define to_s3c_chip(chip) container_of(chip, struct s3c_chip, chip)
#define pwm_dbg(_pwm, msg...) dev_dbg(&(_pwm)->pdev->dev, msg)
static struct clk *clk_scaler[2];
static inline int pwm_is_tdiv(struct s3c_chip *chip)
{
return clk_get_parent(chip->clk) == chip->clk_div;
}
#define pwm_tcon_start(pwm) (1 << (pwm->tcon_base + 0))
#define pwm_tcon_invert(pwm) (1 << (pwm->tcon_base + 2))
#define pwm_tcon_autoreload(pwm) (1 << (pwm->tcon_base + 3))
#define pwm_tcon_manulupdate(pwm) (1 << (pwm->tcon_base + 1))
static int s3c_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct s3c_chip *s3c = to_s3c_chip(chip);
unsigned long flags;
unsigned long tcon;
local_irq_save(flags);
tcon = __raw_readl(S3C2410_TCON);
tcon |= pwm_tcon_start(s3c);
__raw_writel(tcon, S3C2410_TCON);
local_irq_restore(flags);
return 0;
}
static void s3c_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct s3c_chip *s3c = to_s3c_chip(chip);
unsigned long flags;
unsigned long tcon;
local_irq_save(flags);
tcon = __raw_readl(S3C2410_TCON);
tcon &= ~pwm_tcon_start(s3c);
__raw_writel(tcon, S3C2410_TCON);
local_irq_restore(flags);
}
static unsigned long pwm_calc_tin(struct s3c_chip *s3c, unsigned long freq)
{
unsigned long tin_parent_rate;
unsigned int div;
tin_parent_rate = clk_get_rate(clk_get_parent(s3c->clk_div));
pwm_dbg(s3c, "tin parent at %lu\n", tin_parent_rate);
for (div = 2; div <= 16; div *= 2) {
if ((tin_parent_rate / (div << 16)) < freq)
return tin_parent_rate / div;
}
return tin_parent_rate / 16;
}
#define NS_IN_HZ (1000000000UL)
static int s3c_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
int duty_ns, int period_ns)
{
struct s3c_chip *s3c = to_s3c_chip(chip);
unsigned long tin_rate;
unsigned long tin_ns;
unsigned long period;
unsigned long flags;
unsigned long tcon;
unsigned long tcnt;
long tcmp;
/* We currently avoid using 64bit arithmetic by using the
* fact that anything faster than 1Hz is easily representable
* by 32bits. */
if (period_ns > NS_IN_HZ || duty_ns > NS_IN_HZ)
return -ERANGE;
if (period_ns == s3c->period_ns &&
duty_ns == s3c->duty_ns)
return 0;
/* The TCMP and TCNT can be read without a lock, they're not
* shared between the timers. */
tcmp = __raw_readl(S3C2410_TCMPB(s3c->pwm_id));
tcnt = __raw_readl(S3C2410_TCNTB(s3c->pwm_id));
period = NS_IN_HZ / period_ns;
pwm_dbg(s3c, "duty_ns=%d, period_ns=%d (%lu)\n",
duty_ns, period_ns, period);
/* Check to see if we are changing the clock rate of the PWM */
if (s3c->period_ns != period_ns) {
if (pwm_is_tdiv(s3c)) {
tin_rate = pwm_calc_tin(s3c, period);
clk_set_rate(s3c->clk_div, tin_rate);
} else
tin_rate = clk_get_rate(s3c->clk);
s3c->period_ns = period_ns;
pwm_dbg(s3c, "tin_rate=%lu\n", tin_rate);
tin_ns = NS_IN_HZ / tin_rate;
tcnt = period_ns / tin_ns;
} else
tin_ns = NS_IN_HZ / clk_get_rate(s3c->clk);
/* Note, counters count down */
tcmp = duty_ns / tin_ns;
tcmp = tcnt - tcmp;
/* the pwm hw only checks the compare register after a decrement,
so the pin never toggles if tcmp = tcnt */
if (tcmp == tcnt)
tcmp--;
pwm_dbg(s3c, "tin_ns=%lu, tcmp=%ld/%lu\n", tin_ns, tcmp, tcnt);
if (tcmp < 0)
tcmp = 0;
/* Update the PWM register block. */
local_irq_save(flags);
__raw_writel(tcmp, S3C2410_TCMPB(s3c->pwm_id));
__raw_writel(tcnt, S3C2410_TCNTB(s3c->pwm_id));
tcon = __raw_readl(S3C2410_TCON);
tcon |= pwm_tcon_manulupdate(s3c);
tcon |= pwm_tcon_autoreload(s3c);
__raw_writel(tcon, S3C2410_TCON);
tcon &= ~pwm_tcon_manulupdate(s3c);
__raw_writel(tcon, S3C2410_TCON);
local_irq_restore(flags);
return 0;
}
static struct pwm_ops s3c_pwm_ops = {
.enable = s3c_pwm_enable,
.disable = s3c_pwm_disable,
.config = s3c_pwm_config,
.owner = THIS_MODULE,
};
static int s3c_pwm_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct s3c_chip *s3c;
unsigned long flags;
unsigned long tcon;
unsigned int id = pdev->id;
int ret;
if (id == 4) {
dev_err(dev, "TIMER4 is currently not supported\n");
return -ENXIO;
}
s3c = devm_kzalloc(&pdev->dev, sizeof(*s3c), GFP_KERNEL);
if (s3c == NULL) {
dev_err(dev, "failed to allocate pwm_device\n");
return -ENOMEM;
}
/* calculate base of control bits in TCON */
s3c->tcon_base = id == 0 ? 0 : (id * 4) + 4;
s3c->pwm_id = id;
s3c->chip.dev = &pdev->dev;
s3c->chip.ops = &s3c_pwm_ops;
s3c->chip.base = -1;
s3c->chip.npwm = 1;
s3c->clk = devm_clk_get(dev, "pwm-tin");
if (IS_ERR(s3c->clk)) {
dev_err(dev, "failed to get pwm tin clk\n");
return PTR_ERR(s3c->clk);
}
s3c->clk_div = devm_clk_get(dev, "pwm-tdiv");
if (IS_ERR(s3c->clk_div)) {
dev_err(dev, "failed to get pwm tdiv clk\n");
return PTR_ERR(s3c->clk_div);
}
clk_enable(s3c->clk);
clk_enable(s3c->clk_div);
local_irq_save(flags);
tcon = __raw_readl(S3C2410_TCON);
tcon |= pwm_tcon_invert(s3c);
__raw_writel(tcon, S3C2410_TCON);
local_irq_restore(flags);
ret = pwmchip_add(&s3c->chip);
if (ret < 0) {
dev_err(dev, "failed to register pwm\n");
goto err_clk_tdiv;
}
pwm_dbg(s3c, "config bits %02x\n",
(__raw_readl(S3C2410_TCON) >> s3c->tcon_base) & 0x0f);
dev_info(dev, "tin at %lu, tdiv at %lu, tin=%sclk, base %d\n",
clk_get_rate(s3c->clk),
clk_get_rate(s3c->clk_div),
pwm_is_tdiv(s3c) ? "div" : "ext", s3c->tcon_base);
platform_set_drvdata(pdev, s3c);
return 0;
err_clk_tdiv:
clk_disable(s3c->clk_div);
clk_disable(s3c->clk);
return ret;
}
static int s3c_pwm_remove(struct platform_device *pdev)
{
struct s3c_chip *s3c = platform_get_drvdata(pdev);
int err;
err = pwmchip_remove(&s3c->chip);
if (err < 0)
return err;
clk_disable(s3c->clk_div);
clk_disable(s3c->clk);
return 0;
}
#ifdef CONFIG_PM
static int s3c_pwm_suspend(struct platform_device *pdev, pm_message_t state)
{
struct s3c_chip *s3c = platform_get_drvdata(pdev);
/* No one preserve these values during suspend so reset them
* Otherwise driver leaves PWM unconfigured if same values
* passed to pwm_config
*/
s3c->period_ns = 0;
s3c->duty_ns = 0;
return 0;
}
static int s3c_pwm_resume(struct platform_device *pdev)
{
struct s3c_chip *s3c = platform_get_drvdata(pdev);
unsigned long tcon;
/* Restore invertion */
tcon = __raw_readl(S3C2410_TCON);
tcon |= pwm_tcon_invert(s3c);
__raw_writel(tcon, S3C2410_TCON);
return 0;
}
#else
#define s3c_pwm_suspend NULL
#define s3c_pwm_resume NULL
#endif
static struct platform_driver s3c_pwm_driver = {
.driver = {
.name = "s3c24xx-pwm",
.owner = THIS_MODULE,
},
.probe = s3c_pwm_probe,
.remove = s3c_pwm_remove,
.suspend = s3c_pwm_suspend,
.resume = s3c_pwm_resume,
};
static int __init pwm_init(void)
{
int ret;
clk_scaler[0] = clk_get(NULL, "pwm-scaler0");
clk_scaler[1] = clk_get(NULL, "pwm-scaler1");
if (IS_ERR(clk_scaler[0]) || IS_ERR(clk_scaler[1])) {
pr_err("failed to get scaler clocks\n");
return -EINVAL;
}
ret = platform_driver_register(&s3c_pwm_driver);
if (ret)
pr_err("failed to add pwm driver\n");
return ret;
}
arch_initcall(pwm_init);
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