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