drivers/pwm/pwm-jz4740.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/clk.h>
  17 #include <linux/err.h>
  18 #include <linux/gpio.h>
  19 #include <linux/kernel.h>
  20 #include <linux/module.h>
  21 #include <linux/platform_device.h>
  22 #include <linux/pwm.h>
  23
  24 #include <asm/mach-jz4740/gpio.h>
  25 #include <asm/mach-jz4740/timer.h>
  26
  27 #define NUM_PWM 8
  28
  29 static const unsigned int jz4740_pwm_gpio_list[NUM_PWM] = {
  30         JZ_GPIO_PWM0,
  31         JZ_GPIO_PWM1,
  32         JZ_GPIO_PWM2,
  33         JZ_GPIO_PWM3,
  34         JZ_GPIO_PWM4,
  35         JZ_GPIO_PWM5,
  36         JZ_GPIO_PWM6,
  37         JZ_GPIO_PWM7,
  38 };
  39
  40 struct jz4740_pwm_chip {
  41         struct pwm_chip chip;
  42         struct clk *clk;
  43 };
  44
  45 static inline struct jz4740_pwm_chip *to_jz4740(struct pwm_chip *chip)
  46 {
  47         return container_of(chip, struct jz4740_pwm_chip, chip);
  48 }
  49
  50 static int jz4740_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
  51 {
  52         unsigned int gpio = jz4740_pwm_gpio_list[pwm->hwpwm];
  53         int ret;
  54
  55         /*
  56          * Timers 0 and 1 are used for system tasks, so they are unavailable
  57          * for use as PWMs.
  58          */
  59         if (pwm->hwpwm < 2)
  60                 return -EBUSY;
  61
  62         ret = gpio_request(gpio, pwm->label);
  63         if (ret) {
  64                 dev_err(chip->dev, "Failed to request GPIO#%u for PWM: %d\n",
  65                         gpio, ret);
  66                 return ret;
  67         }
  68
  69         jz_gpio_set_function(gpio, JZ_GPIO_FUNC_PWM);
  70
  71         jz4740_timer_start(pwm->hwpwm);
  72
  73         return 0;
  74 }
  75
  76 static void jz4740_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
  77 {
  78         unsigned int gpio = jz4740_pwm_gpio_list[pwm->hwpwm];
  79
  80         jz4740_timer_set_ctrl(pwm->hwpwm, 0);
  81
  82         jz_gpio_set_function(gpio, JZ_GPIO_FUNC_NONE);
  83         gpio_free(gpio);
  84
  85         jz4740_timer_stop(pwm->hwpwm);
  86 }
  87
  88 static int jz4740_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
  89 {
  90         uint32_t ctrl = jz4740_timer_get_ctrl(pwm->pwm);
  91
  92         ctrl |= JZ_TIMER_CTRL_PWM_ENABLE;
  93         jz4740_timer_set_ctrl(pwm->hwpwm, ctrl);
  94         jz4740_timer_enable(pwm->hwpwm);
  95
  96         return 0;
  97 }
  98
  99 static void jz4740_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 100 {
 101         uint32_t ctrl = jz4740_timer_get_ctrl(pwm->hwpwm);
 102
 103         ctrl &= ~JZ_TIMER_CTRL_PWM_ENABLE;
 104         jz4740_timer_disable(pwm->hwpwm);
 105         jz4740_timer_set_ctrl(pwm->hwpwm, ctrl);
 106 }
 107
 108 static int jz4740_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 109                              int duty_ns, int period_ns)
 110 {
 111         struct jz4740_pwm_chip *jz4740 = to_jz4740(pwm->chip);
 112         unsigned long long tmp;
 113         unsigned long period, duty;
 114         unsigned int prescaler = 0;
 115         uint16_t ctrl;
 116         bool is_enabled;
 117
 118         tmp = (unsigned long long)clk_get_rate(jz4740->clk) * period_ns;
 119         do_div(tmp, 1000000000);
 120         period = tmp;
 121
 122         while (period > 0xffff && prescaler < 6) {
 123                 period >>= 2;
 124                 ++prescaler;
 125         }
 126
 127         if (prescaler == 6)
 128                 return -EINVAL;
 129
 130         tmp = (unsigned long long)period * duty_ns;
 131         do_div(tmp, period_ns);
 132         duty = period - tmp;
 133
 134         if (duty >= period)
 135                 duty = period - 1;
 136
 137         is_enabled = jz4740_timer_is_enabled(pwm->hwpwm);
 138         if (is_enabled)
 139                 jz4740_pwm_disable(chip, pwm);
 140
 141         jz4740_timer_set_count(pwm->hwpwm, 0);
 142         jz4740_timer_set_duty(pwm->hwpwm, duty);
 143         jz4740_timer_set_period(pwm->hwpwm, period);
 144
 145         ctrl = JZ_TIMER_CTRL_PRESCALER(prescaler) | JZ_TIMER_CTRL_SRC_EXT |
 146                 JZ_TIMER_CTRL_PWM_ABBRUPT_SHUTDOWN;
 147
 148         jz4740_timer_set_ctrl(pwm->hwpwm, ctrl);
 149
 150         if (is_enabled)
 151                 jz4740_pwm_enable(chip, pwm);
 152
 153         return 0;
 154 }
 155
 156 static const struct pwm_ops jz4740_pwm_ops = {
 157         .request = jz4740_pwm_request,
 158         .free = jz4740_pwm_free,
 159         .config = jz4740_pwm_config,
 160         .enable = jz4740_pwm_enable,
 161         .disable = jz4740_pwm_disable,
 162         .owner = THIS_MODULE,
 163 };
 164
 165 static int jz4740_pwm_probe(struct platform_device *pdev)
 166 {
 167         struct jz4740_pwm_chip *jz4740;
 168
 169         jz4740 = devm_kzalloc(&pdev->dev, sizeof(*jz4740), GFP_KERNEL);
 170         if (!jz4740)
 171                 return -ENOMEM;
 172
 173         jz4740->clk = devm_clk_get(&pdev->dev, "ext");
 174         if (IS_ERR(jz4740->clk))
 175                 return PTR_ERR(jz4740->clk);
 176
 177         jz4740->chip.dev = &pdev->dev;
 178         jz4740->chip.ops = &jz4740_pwm_ops;
 179         jz4740->chip.npwm = NUM_PWM;
 180         jz4740->chip.base = -1;
 181
 182         platform_set_drvdata(pdev, jz4740);
 183
 184         return pwmchip_add(&jz4740->chip);
 185 }
 186
 187 static int jz4740_pwm_remove(struct platform_device *pdev)
 188 {
 189         struct jz4740_pwm_chip *jz4740 = platform_get_drvdata(pdev);
 190
 191         return pwmchip_remove(&jz4740->chip);
 192 }
 193
 194 static struct platform_driver jz4740_pwm_driver = {
 195         .driver = {
 196                 .name = "jz4740-pwm",
 197                 .owner = THIS_MODULE,
 198         },
 199         .probe = jz4740_pwm_probe,
 200         .remove = jz4740_pwm_remove,
 201 };
 202 module_platform_driver(jz4740_pwm_driver);
 203
 204 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
 205 MODULE_DESCRIPTION("Ingenic JZ4740 PWM driver");
 206 MODULE_ALIAS("platform:jz4740-pwm");
 207 MODULE_LICENSE("GPL");