diff options
Diffstat (limited to 'arch/mips/jz4740/pwm.c')
| -rw-r--r-- | arch/mips/jz4740/pwm.c | 177 |
1 files changed, 177 insertions, 0 deletions
diff --git a/arch/mips/jz4740/pwm.c b/arch/mips/jz4740/pwm.c new file mode 100644 index 0000000..a26a6fa --- /dev/null +++ b/arch/mips/jz4740/pwm.c @@ -0,0 +1,177 @@ +/* + * 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/kernel.h> + +#include <linux/clk.h> +#include <linux/err.h> +#include <linux/pwm.h> +#include <linux/gpio.h> + +#include <asm/mach-jz4740/gpio.h> +#include "timer.h" + +static struct clk *jz4740_pwm_clk; + +DEFINE_MUTEX(jz4740_pwm_mutex); + +struct pwm_device { + unsigned int id; + unsigned int gpio; + bool used; +}; + +static struct pwm_device jz4740_pwm_list[] = { + { 2, JZ_GPIO_PWM2, false }, + { 3, JZ_GPIO_PWM3, false }, + { 4, JZ_GPIO_PWM4, false }, + { 5, JZ_GPIO_PWM5, false }, + { 6, JZ_GPIO_PWM6, false }, + { 7, JZ_GPIO_PWM7, false }, +}; + +struct pwm_device *pwm_request(int id, const char *label) +{ + int ret = 0; + struct pwm_device *pwm; + + if (id < 2 || id > 7 || !jz4740_pwm_clk) + return ERR_PTR(-ENODEV); + + mutex_lock(&jz4740_pwm_mutex); + + pwm = &jz4740_pwm_list[id - 2]; + if (pwm->used) + ret = -EBUSY; + else + pwm->used = true; + + mutex_unlock(&jz4740_pwm_mutex); + + if (ret) + return ERR_PTR(ret); + + ret = gpio_request(pwm->gpio, label); + + if (ret) { + printk(KERN_ERR "Failed to request pwm gpio: %d\n", ret); + pwm->used = false; + return ERR_PTR(ret); + } + + jz_gpio_set_function(pwm->gpio, JZ_GPIO_FUNC_PWM); + + jz4740_timer_start(id); + + return pwm; +} + +void pwm_free(struct pwm_device *pwm) +{ + pwm_disable(pwm); + jz4740_timer_set_ctrl(pwm->id, 0); + + jz_gpio_set_function(pwm->gpio, JZ_GPIO_FUNC_NONE); + gpio_free(pwm->gpio); + + jz4740_timer_stop(pwm->id); + + pwm->used = false; +} + +int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns) +{ + unsigned long long tmp; + unsigned long period, duty; + unsigned int prescaler = 0; + unsigned int id = pwm->id; + uint16_t ctrl; + bool is_enabled; + + if (duty_ns < 0 || duty_ns > period_ns) + return -EINVAL; + + tmp = (unsigned long long)clk_get_rate(jz4740_pwm_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(id); + if (is_enabled) + pwm_disable(pwm); + + jz4740_timer_set_count(id, 0); + jz4740_timer_set_duty(id, duty); + jz4740_timer_set_period(id, period); + + ctrl = JZ_TIMER_CTRL_PRESCALER(prescaler) | JZ_TIMER_CTRL_SRC_EXT | + JZ_TIMER_CTRL_PWM_ABBRUPT_SHUTDOWN; + + jz4740_timer_set_ctrl(id, ctrl); + + if (is_enabled) + pwm_enable(pwm); + + return 0; +} + +int pwm_enable(struct pwm_device *pwm) +{ + uint32_t ctrl = jz4740_timer_get_ctrl(pwm->id); + + ctrl |= JZ_TIMER_CTRL_PWM_ENABLE; + jz4740_timer_set_ctrl(pwm->id, ctrl); + jz4740_timer_enable(pwm->id); + + return 0; +} + +void pwm_disable(struct pwm_device *pwm) +{ + uint32_t ctrl = jz4740_timer_get_ctrl(pwm->id); + + ctrl &= ~JZ_TIMER_CTRL_PWM_ENABLE; + jz4740_timer_disable(pwm->id); + jz4740_timer_set_ctrl(pwm->id, ctrl); +} + +static int __init jz4740_pwm_init(void) +{ + int ret = 0; + + jz4740_pwm_clk = clk_get(NULL, "ext"); + + if (IS_ERR(jz4740_pwm_clk)) { + ret = PTR_ERR(jz4740_pwm_clk); + jz4740_pwm_clk = NULL; + } + + return ret; +} +subsys_initcall(jz4740_pwm_init); |
