pwm-jz4740.c
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/*
* Copyright (C) 2010, Lars-Peter Clausen <lars@metafoo.de>
* JZ4740 platform PWM support
*
* 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, or (at your
* option) any later version.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 675 Mass Ave, Cambridge, MA 02139, USA.
*
*/
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/gpio.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>
#include <asm/mach-jz4740/timer.h>
#define NUM_PWM 8
struct jz4740_pwm_chip {
struct pwm_chip chip;
struct clk *clk;
};
static inline struct jz4740_pwm_chip *to_jz4740(struct pwm_chip *chip)
{
return container_of(chip, struct jz4740_pwm_chip, chip);
}
static int jz4740_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
{
/*
* Timers 0 and 1 are used for system tasks, so they are unavailable
* for use as PWMs.
*/
if (pwm->hwpwm < 2)
return -EBUSY;
jz4740_timer_start(pwm->hwpwm);
return 0;
}
static void jz4740_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
{
jz4740_timer_set_ctrl(pwm->hwpwm, 0);
jz4740_timer_stop(pwm->hwpwm);
}
static int jz4740_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
uint32_t ctrl = jz4740_timer_get_ctrl(pwm->pwm);
ctrl |= JZ_TIMER_CTRL_PWM_ENABLE;
jz4740_timer_set_ctrl(pwm->hwpwm, ctrl);
jz4740_timer_enable(pwm->hwpwm);
return 0;
}
static void jz4740_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
uint32_t ctrl = jz4740_timer_get_ctrl(pwm->hwpwm);
ctrl &= ~JZ_TIMER_CTRL_PWM_ENABLE;
jz4740_timer_disable(pwm->hwpwm);
jz4740_timer_set_ctrl(pwm->hwpwm, ctrl);
}
static int jz4740_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
int duty_ns, int period_ns)
{
struct jz4740_pwm_chip *jz4740 = to_jz4740(pwm->chip);
unsigned long long tmp;
unsigned long period, duty;
unsigned int prescaler = 0;
uint16_t ctrl;
bool is_enabled;
tmp = (unsigned long long)clk_get_rate(jz4740->clk) * period_ns;
do_div(tmp, 1000000000);
period = tmp;
while (period > 0xffff && prescaler < 6) {
period >>= 2;
++prescaler;
}
if (prescaler == 6)
return -EINVAL;
tmp = (unsigned long long)period * duty_ns;
do_div(tmp, period_ns);
duty = period - tmp;
if (duty >= period)
duty = period - 1;
is_enabled = jz4740_timer_is_enabled(pwm->hwpwm);
if (is_enabled)
jz4740_pwm_disable(chip, pwm);
jz4740_timer_set_count(pwm->hwpwm, 0);
jz4740_timer_set_duty(pwm->hwpwm, duty);
jz4740_timer_set_period(pwm->hwpwm, period);
ctrl = JZ_TIMER_CTRL_PRESCALER(prescaler) | JZ_TIMER_CTRL_SRC_EXT |
JZ_TIMER_CTRL_PWM_ABBRUPT_SHUTDOWN;
jz4740_timer_set_ctrl(pwm->hwpwm, ctrl);
if (is_enabled)
jz4740_pwm_enable(chip, pwm);
return 0;
}
static const struct pwm_ops jz4740_pwm_ops = {
.request = jz4740_pwm_request,
.free = jz4740_pwm_free,
.config = jz4740_pwm_config,
.enable = jz4740_pwm_enable,
.disable = jz4740_pwm_disable,
.owner = THIS_MODULE,
};
static int jz4740_pwm_probe(struct platform_device *pdev)
{
struct jz4740_pwm_chip *jz4740;
jz4740 = devm_kzalloc(&pdev->dev, sizeof(*jz4740), GFP_KERNEL);
if (!jz4740)
return -ENOMEM;
jz4740->clk = devm_clk_get(&pdev->dev, "ext");
if (IS_ERR(jz4740->clk))
return PTR_ERR(jz4740->clk);
jz4740->chip.dev = &pdev->dev;
jz4740->chip.ops = &jz4740_pwm_ops;
jz4740->chip.npwm = NUM_PWM;
jz4740->chip.base = -1;
platform_set_drvdata(pdev, jz4740);
return pwmchip_add(&jz4740->chip);
}
static int jz4740_pwm_remove(struct platform_device *pdev)
{
struct jz4740_pwm_chip *jz4740 = platform_get_drvdata(pdev);
return pwmchip_remove(&jz4740->chip);
}
static struct platform_driver jz4740_pwm_driver = {
.driver = {
.name = "jz4740-pwm",
},
.probe = jz4740_pwm_probe,
.remove = jz4740_pwm_remove,
};
module_platform_driver(jz4740_pwm_driver);
MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
MODULE_DESCRIPTION("Ingenic JZ4740 PWM driver");
MODULE_ALIAS("platform:jz4740-pwm");
MODULE_LICENSE("GPL");