178 lines
3.5 KiB
C
178 lines
3.5 KiB
C
/*
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* Copyright (C) 2010, Lars-Peter Clausen <lars@metafoo.de>
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* JZ4740 platform PWM support
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 675 Mass Ave, Cambridge, MA 02139, USA.
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*
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*/
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#include <linux/kernel.h>
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#include <linux/clk.h>
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#include <linux/err.h>
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#include <linux/pwm.h>
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#include <linux/gpio.h>
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#include <asm/mach-jz4740/gpio.h>
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#include "timer.h"
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static struct clk *jz4740_pwm_clk;
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DEFINE_MUTEX(jz4740_pwm_mutex);
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struct pwm_device {
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unsigned int id;
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unsigned int gpio;
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bool used;
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};
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static struct pwm_device jz4740_pwm_list[] = {
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{ 2, JZ_GPIO_PWM2, false },
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{ 3, JZ_GPIO_PWM3, false },
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{ 4, JZ_GPIO_PWM4, false },
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{ 5, JZ_GPIO_PWM5, false },
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{ 6, JZ_GPIO_PWM6, false },
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{ 7, JZ_GPIO_PWM7, false },
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};
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struct pwm_device *pwm_request(int id, const char *label)
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{
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int ret = 0;
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struct pwm_device *pwm;
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if (id < 2 || id > 7 || !jz4740_pwm_clk)
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return ERR_PTR(-ENODEV);
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mutex_lock(&jz4740_pwm_mutex);
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pwm = &jz4740_pwm_list[id - 2];
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if (pwm->used)
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ret = -EBUSY;
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else
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pwm->used = true;
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mutex_unlock(&jz4740_pwm_mutex);
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if (ret)
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return ERR_PTR(ret);
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ret = gpio_request(pwm->gpio, label);
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if (ret) {
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printk(KERN_ERR "Failed to request pwm gpio: %d\n", ret);
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pwm->used = false;
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return ERR_PTR(ret);
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}
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jz_gpio_set_function(pwm->gpio, JZ_GPIO_FUNC_PWM);
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jz4740_timer_start(id);
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return pwm;
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}
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void pwm_free(struct pwm_device *pwm)
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{
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pwm_disable(pwm);
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jz4740_timer_set_ctrl(pwm->id, 0);
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jz_gpio_set_function(pwm->gpio, JZ_GPIO_FUNC_NONE);
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gpio_free(pwm->gpio);
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jz4740_timer_stop(pwm->id);
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pwm->used = false;
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}
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int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
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{
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unsigned long long tmp;
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unsigned long period, duty;
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unsigned int prescaler = 0;
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unsigned int id = pwm->id;
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uint16_t ctrl;
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bool is_enabled;
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if (duty_ns < 0 || duty_ns > period_ns)
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return -EINVAL;
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tmp = (unsigned long long)clk_get_rate(jz4740_pwm_clk) * period_ns;
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do_div(tmp, 1000000000);
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period = tmp;
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while (period > 0xffff && prescaler < 6) {
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period >>= 2;
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++prescaler;
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}
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if (prescaler == 6)
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return -EINVAL;
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tmp = (unsigned long long)period * duty_ns;
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do_div(tmp, period_ns);
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duty = period - tmp;
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if (duty >= period)
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duty = period - 1;
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is_enabled = jz4740_timer_is_enabled(id);
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if (is_enabled)
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pwm_disable(pwm);
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jz4740_timer_set_count(id, 0);
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jz4740_timer_set_duty(id, duty);
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jz4740_timer_set_period(id, period);
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ctrl = JZ_TIMER_CTRL_PRESCALER(prescaler) | JZ_TIMER_CTRL_SRC_EXT |
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JZ_TIMER_CTRL_PWM_ABBRUPT_SHUTDOWN;
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jz4740_timer_set_ctrl(id, ctrl);
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if (is_enabled)
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pwm_enable(pwm);
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return 0;
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}
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int pwm_enable(struct pwm_device *pwm)
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{
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uint32_t ctrl = jz4740_timer_get_ctrl(pwm->id);
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ctrl |= JZ_TIMER_CTRL_PWM_ENABLE;
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jz4740_timer_set_ctrl(pwm->id, ctrl);
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jz4740_timer_enable(pwm->id);
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return 0;
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}
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void pwm_disable(struct pwm_device *pwm)
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{
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uint32_t ctrl = jz4740_timer_get_ctrl(pwm->id);
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ctrl &= ~JZ_TIMER_CTRL_PWM_ENABLE;
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jz4740_timer_disable(pwm->id);
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jz4740_timer_set_ctrl(pwm->id, ctrl);
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}
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static int __init jz4740_pwm_init(void)
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{
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int ret = 0;
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jz4740_pwm_clk = clk_get(NULL, "ext");
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if (IS_ERR(jz4740_pwm_clk)) {
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ret = PTR_ERR(jz4740_pwm_clk);
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jz4740_pwm_clk = NULL;
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}
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return ret;
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}
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subsys_initcall(jz4740_pwm_init);
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