target/linux/xburst/patches-2.6.35/011-pwm.patch

   1 From 5cd5a44b94b451ecaf593bb49919cfbb51ccb622 Mon Sep 17 00:00:00 2001
   2 From: Lars-Peter Clausen <lars@metafoo.de>
   3 Date: Sat, 17 Jul 2010 11:12:20 +0000
   4 Subject: [PATCH] MIPS: JZ4740: Add PWM support
   5
   6 Add support for the PWM part of the timer unit on a JZ4740 SoC.
   7
   8 Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
   9 Cc: linux-mips@linux-mips.org
  10 Cc: linux-kernel@vger.kernel.org
  11 Patchwork: https://patchwork.linux-mips.org/patch/1468/
  12 Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
  13 ---
  14  arch/mips/jz4740/pwm.c |  177 ++++++++++++++++++++++++++++++++++++++++++++++++
  15  1 files changed, 177 insertions(+), 0 deletions(-)
  16  create mode 100644 arch/mips/jz4740/pwm.c
  17
  18 --- /dev/null
  19 +++ b/arch/mips/jz4740/pwm.c
  20 @@ -0,0 +1,177 @@
  21 +/*
  22 + *  Copyright (C) 2010, Lars-Peter Clausen <lars@metafoo.de>
  23 + *  JZ4740 platform PWM support
  24 + *
  25 + *  This program is free software; you can redistribute it and/or modify it
  26 + *  under  the terms of the GNU General  Public License as published by the
  27 + *  Free Software Foundation;  either version 2 of the License, or (at your
  28 + *  option) any later version.
  29 + *
  30 + *  You should have received a copy of the GNU General Public License along
  31 + *  with this program; if not, write to the Free Software Foundation, Inc.,
  32 + *  675 Mass Ave, Cambridge, MA 02139, USA.
  33 + *
  34 + */
  35 +
  36 +#include <linux/kernel.h>
  37 +
  38 +#include <linux/clk.h>
  39 +#include <linux/err.h>
  40 +#include <linux/pwm.h>
  41 +#include <linux/gpio.h>
  42 +
  43 +#include <asm/mach-jz4740/gpio.h>
  44 +#include "timer.h"
  45 +
  46 +static struct clk *jz4740_pwm_clk;
  47 +
  48 +DEFINE_MUTEX(jz4740_pwm_mutex);
  49 +
  50 +struct pwm_device {
  51 +       unsigned int id;
  52 +       unsigned int gpio;
  53 +       bool used;
  54 +};
  55 +
  56 +static struct pwm_device jz4740_pwm_list[] = {
  57 +       { 2, JZ_GPIO_PWM2, false },
  58 +       { 3, JZ_GPIO_PWM3, false },
  59 +       { 4, JZ_GPIO_PWM4, false },
  60 +       { 5, JZ_GPIO_PWM5, false },
  61 +       { 6, JZ_GPIO_PWM6, false },
  62 +       { 7, JZ_GPIO_PWM7, false },
  63 +};
  64 +
  65 +struct pwm_device *pwm_request(int id, const char *label)
  66 +{
  67 +       int ret = 0;
  68 +       struct pwm_device *pwm;
  69 +
  70 +       if (id < 2 || id > 7 || !jz4740_pwm_clk)
  71 +               return ERR_PTR(-ENODEV);
  72 +
  73 +       mutex_lock(&jz4740_pwm_mutex);
  74 +
  75 +       pwm = &jz4740_pwm_list[id - 2];
  76 +       if (pwm->used)
  77 +               ret = -EBUSY;
  78 +       else
  79 +               pwm->used = true;
  80 +
  81 +       mutex_unlock(&jz4740_pwm_mutex);
  82 +
  83 +       if (ret)
  84 +               return ERR_PTR(ret);
  85 +
  86 +       ret = gpio_request(pwm->gpio, label);
  87 +
  88 +       if (ret) {
  89 +               printk(KERN_ERR "Failed to request pwm gpio: %d\n", ret);
  90 +               pwm->used = false;
  91 +               return ERR_PTR(ret);
  92 +       }
  93 +
  94 +       jz_gpio_set_function(pwm->gpio, JZ_GPIO_FUNC_PWM);
  95 +
  96 +       jz4740_timer_start(id);
  97 +
  98 +       return pwm;
  99 +}
 100 +
 101 +void pwm_free(struct pwm_device *pwm)
 102 +{
 103 +       pwm_disable(pwm);
 104 +       jz4740_timer_set_ctrl(pwm->id, 0);
 105 +
 106 +       jz_gpio_set_function(pwm->gpio, JZ_GPIO_FUNC_NONE);
 107 +       gpio_free(pwm->gpio);
 108 +
 109 +       jz4740_timer_stop(pwm->id);
 110 +
 111 +       pwm->used = false;
 112 +}
 113 +
 114 +int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
 115 +{
 116 +       unsigned long long tmp;
 117 +       unsigned long period, duty;
 118 +       unsigned int prescaler = 0;
 119 +       unsigned int id = pwm->id;
 120 +       uint16_t ctrl;
 121 +       bool is_enabled;
 122 +
 123 +       if (duty_ns < 0 || duty_ns > period_ns)
 124 +               return -EINVAL;
 125 +
 126 +       tmp = (unsigned long long)clk_get_rate(jz4740_pwm_clk) * period_ns;
 127 +       do_div(tmp, 1000000000);
 128 +       period = tmp;
 129 +
 130 +       while (period > 0xffff && prescaler < 6) {
 131 +               period >>= 2;
 132 +               ++prescaler;
 133 +       }
 134 +
 135 +       if (prescaler == 6)
 136 +               return -EINVAL;
 137 +
 138 +       tmp = (unsigned long long)period * duty_ns;
 139 +       do_div(tmp, period_ns);
 140 +       duty = period - tmp;
 141 +
 142 +       if (duty >= period)
 143 +               duty = period - 1;
 144 +
 145 +       is_enabled = jz4740_timer_is_enabled(id);
 146 +       if (is_enabled)
 147 +               pwm_disable(pwm);
 148 +
 149 +       jz4740_timer_set_count(id, 0);
 150 +       jz4740_timer_set_duty(id, duty);
 151 +       jz4740_timer_set_period(id, period);
 152 +
 153 +       ctrl = JZ_TIMER_CTRL_PRESCALER(prescaler) | JZ_TIMER_CTRL_SRC_EXT |
 154 +               JZ_TIMER_CTRL_PWM_ABBRUPT_SHUTDOWN;
 155 +
 156 +       jz4740_timer_set_ctrl(id, ctrl);
 157 +
 158 +       if (is_enabled)
 159 +               pwm_enable(pwm);
 160 +
 161 +       return 0;
 162 +}
 163 +
 164 +int pwm_enable(struct pwm_device *pwm)
 165 +{
 166 +       uint32_t ctrl = jz4740_timer_get_ctrl(pwm->id);
 167 +
 168 +       ctrl |= JZ_TIMER_CTRL_PWM_ENABLE;
 169 +       jz4740_timer_set_ctrl(pwm->id, ctrl);
 170 +       jz4740_timer_enable(pwm->id);
 171 +
 172 +       return 0;
 173 +}
 174 +
 175 +void pwm_disable(struct pwm_device *pwm)
 176 +{
 177 +       uint32_t ctrl = jz4740_timer_get_ctrl(pwm->id);
 178 +
 179 +       ctrl &= ~JZ_TIMER_CTRL_PWM_ENABLE;
 180 +       jz4740_timer_disable(pwm->id);
 181 +       jz4740_timer_set_ctrl(pwm->id, ctrl);
 182 +}
 183 +
 184 +static int __init jz4740_pwm_init(void)
 185 +{
 186 +       int ret = 0;
 187 +
 188 +       jz4740_pwm_clk = clk_get(NULL, "ext");
 189 +
 190 +       if (IS_ERR(jz4740_pwm_clk)) {
 191 +               ret = PTR_ERR(jz4740_pwm_clk);
 192 +               jz4740_pwm_clk = NULL;
 193 +       }
 194 +
 195 +       return ret;
 196 +}
 197 +subsys_initcall(jz4740_pwm_init);