LXR linux/arch/mips/jz4740/pwm.c

   1/*
   2 *  Copyright (C) 2010, Lars-Peter Clausen <lars@metafoo.de>
   3 *  JZ4740 platform PWM support
   4 *
   5 *  This program is free software; you can redistribute it and/or modify it
   6 *  under  the terms of the GNU General  Public License as published by the
   7 *  Free Software Foundation;  either version 2 of the License, or (at your
   8 *  option) any later version.
   9 *
  10 *  You should have received a copy of the GNU General Public License along
  11 *  with this program; if not, write to the Free Software Foundation, Inc.,
  12 *  675 Mass Ave, Cambridge, MA 02139, USA.
  13 *
  14 */
  15
  16#include <linux/kernel.h>
  17
  18#include <linux/clk.h>
  19#include <linux/err.h>
  20#include <linux/pwm.h>
  21#include <linux/gpio.h>
  22
  23#include <asm/mach-jz4740/gpio.h>
  24#include "timer.h"
  25
  26static struct clk *jz4740_pwm_clk;
  27
  28DEFINE_MUTEX(jz4740_pwm_mutex);
  29
  30struct pwm_device {
  31        unsigned int id;
  32        unsigned int gpio;
  33        bool used;
  34};
  35
  36static struct pwm_device jz4740_pwm_list[] = {
  37        { 2, JZ_GPIO_PWM2, false },
  38        { 3, JZ_GPIO_PWM3, false },
  39        { 4, JZ_GPIO_PWM4, false },
  40        { 5, JZ_GPIO_PWM5, false },
  41        { 6, JZ_GPIO_PWM6, false },
  42        { 7, JZ_GPIO_PWM7, false },
  43};
  44
  45struct pwm_device *pwm_request(int id, const char *label)
  46{
  47        int ret = 0;
  48        struct pwm_device *pwm;
  49
  50        if (id < 2 || id > 7 || !jz4740_pwm_clk)
  51                return ERR_PTR(-ENODEV);
  52
  53        mutex_lock(&jz4740_pwm_mutex);
  54
  55        pwm = &jz4740_pwm_list[id - 2];
  56        if (pwm->used)
  57                ret = -EBUSY;
  58        else
  59                pwm->used = true;
  60
  61        mutex_unlock(&jz4740_pwm_mutex);
  62
  63        if (ret)
  64                return ERR_PTR(ret);
  65
  66        ret = gpio_request(pwm->gpio, label);
  67
  68        if (ret) {
  69                printk(KERN_ERR "Failed to request pwm gpio: %d\n", ret);
  70                pwm->used = false;
  71                return ERR_PTR(ret);
  72        }
  73
  74        jz_gpio_set_function(pwm->gpio, JZ_GPIO_FUNC_PWM);
  75
  76        jz4740_timer_start(id);
  77
  78        return pwm;
  79}
  80
  81void pwm_free(struct pwm_device *pwm)
  82{
  83        pwm_disable(pwm);
  84        jz4740_timer_set_ctrl(pwm->id, 0);
  85
  86        jz_gpio_set_function(pwm->gpio, JZ_GPIO_FUNC_NONE);
  87        gpio_free(pwm->gpio);
  88
  89        jz4740_timer_stop(pwm->id);
  90
  91        pwm->used = false;
  92}
  93
  94int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
  95{
  96        unsigned long long tmp;
  97        unsigned long period, duty;
  98        unsigned int prescaler = 0;
  99        unsigned int id = pwm->id;
 100        uint16_t ctrl;
 101        bool is_enabled;
 102
 103        if (duty_ns < 0 || duty_ns > period_ns)
 104                return -EINVAL;
 105
 106        tmp = (unsigned long long)clk_get_rate(jz4740_pwm_clk) * period_ns;
 107        do_div(tmp, 1000000000);
 108        period = tmp;
 109
 110        while (period > 0xffff && prescaler < 6) {
 111                period >>= 2;
 112                ++prescaler;
 113        }
 114
 115        if (prescaler == 6)
 116                return -EINVAL;
 117
 118        tmp = (unsigned long long)period * duty_ns;
 119        do_div(tmp, period_ns);
 120        duty = period - tmp;
 121
 122        if (duty >= period)
 123                duty = period - 1;
 124
 125        is_enabled = jz4740_timer_is_enabled(id);
 126        if (is_enabled)
 127                pwm_disable(pwm);
 128
 129        jz4740_timer_set_count(id, 0);
 130        jz4740_timer_set_duty(id, duty);
 131        jz4740_timer_set_period(id, period);
 132
 133        ctrl = JZ_TIMER_CTRL_PRESCALER(prescaler) | JZ_TIMER_CTRL_SRC_EXT |
 134                JZ_TIMER_CTRL_PWM_ABBRUPT_SHUTDOWN;
 135
 136        jz4740_timer_set_ctrl(id, ctrl);
 137
 138        if (is_enabled)
 139                pwm_enable(pwm);
 140
 141        return 0;
 142}
 143
 144int pwm_enable(struct pwm_device *pwm)
 145{
 146        uint32_t ctrl = jz4740_timer_get_ctrl(pwm->id);
 147
 148        ctrl |= JZ_TIMER_CTRL_PWM_ENABLE;
 149        jz4740_timer_set_ctrl(pwm->id, ctrl);
 150        jz4740_timer_enable(pwm->id);
 151
 152        return 0;
 153}
 154
 155void pwm_disable(struct pwm_device *pwm)
 156{
 157        uint32_t ctrl = jz4740_timer_get_ctrl(pwm->id);
 158
 159        ctrl &= ~JZ_TIMER_CTRL_PWM_ENABLE;
 160        jz4740_timer_disable(pwm->id);
 161        jz4740_timer_set_ctrl(pwm->id, ctrl);
 162}
 163
 164static int __init jz4740_pwm_init(void)
 165{
 166        int ret = 0;
 167
 168        jz4740_pwm_clk = clk_get(NULL, "ext");
 169
 170        if (IS_ERR(jz4740_pwm_clk)) {
 171                ret = PTR_ERR(jz4740_pwm_clk);
 172                jz4740_pwm_clk = NULL;
 173        }
 174
 175        return ret;
 176}
 177subsys_initcall(jz4740_pwm_init);
 178