release/src-rt-6.x.4708/linux/linux-2.6.36/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
  26 static struct clk *jz4740_pwm_clk;
  27
  28 DEFINE_MUTEX(jz4740_pwm_mutex);
  29
  30 struct pwm_device {
  31         unsigned int id;
  32         unsigned int gpio;
  33         bool used;
  34 };
  35
  36 static 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
  45 struct 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
  81 void 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
  94 int 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
 144 int 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
 155 void 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
 164 static 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 }
 177 subsys_initcall(jz4740_pwm_init);