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/of_device.h>
  22 #include <linux/platform_device.h>
  23 #include <linux/pwm.h>
  24
  25 #include <asm/mach-jz4740/timer.h>
  26
  27 #define NUM_PWM 8
  28
  29 struct jz4740_pwm_chip {
  30         struct pwm_chip chip;
  31         struct clk *clk;
  32 };
  33
  34 static inline struct jz4740_pwm_chip *to_jz4740(struct pwm_chip *chip)
  35 {
  36         return container_of(chip, struct jz4740_pwm_chip, chip);
  37 }
  38
  39 static int jz4740_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
  40 {
  41         /*
  42          * Timers 0 and 1 are used for system tasks, so they are unavailable
  43          * for use as PWMs.
  44          */
  45         if (pwm->hwpwm < 2)
  46                 return -EBUSY;
  47
  48         jz4740_timer_start(pwm->hwpwm);
  49
  50         return 0;
  51 }
  52
  53 static void jz4740_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
  54 {
  55         jz4740_timer_set_ctrl(pwm->hwpwm, 0);
  56
  57         jz4740_timer_stop(pwm->hwpwm);
  58 }
  59
  60 static int jz4740_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
  61 {
  62         uint32_t ctrl = jz4740_timer_get_ctrl(pwm->pwm);
  63
  64         ctrl |= JZ_TIMER_CTRL_PWM_ENABLE;
  65         jz4740_timer_set_ctrl(pwm->hwpwm, ctrl);
  66         jz4740_timer_enable(pwm->hwpwm);
  67
  68         return 0;
  69 }
  70
  71 static void jz4740_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
  72 {
  73         uint32_t ctrl = jz4740_timer_get_ctrl(pwm->hwpwm);
  74
  75         /* Disable PWM output.
  76          * In TCU2 mode (channel 1/2 on JZ4750+), this must be done before the
  77          * counter is stopped, while in TCU1 mode the order does not matter.
  78          */
  79         ctrl &= ~JZ_TIMER_CTRL_PWM_ENABLE;
  80         jz4740_timer_set_ctrl(pwm->hwpwm, ctrl);
  81
  82         /* Stop counter */
  83         jz4740_timer_disable(pwm->hwpwm);
  84 }
  85
  86 static int jz4740_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
  87                              int duty_ns, int period_ns)
  88 {
  89         struct jz4740_pwm_chip *jz4740 = to_jz4740(pwm->chip);
  90         unsigned long long tmp;
  91         unsigned long period, duty;
  92         unsigned int prescaler = 0;
  93         uint16_t ctrl;
  94         bool is_enabled;
  95
  96         tmp = (unsigned long long)clk_get_rate(jz4740->clk) * period_ns;
  97         do_div(tmp, 1000000000);
  98         period = tmp;
  99
 100         while (period > 0xffff && prescaler < 6) {
 101                 period >>= 2;
 102                 ++prescaler;
 103         }
 104
 105         if (prescaler == 6)
 106                 return -EINVAL;
 107
 108         tmp = (unsigned long long)period * duty_ns;
 109         do_div(tmp, period_ns);
 110         duty = period - tmp;
 111
 112         if (duty >= period)
 113                 duty = period - 1;
 114
 115         is_enabled = jz4740_timer_is_enabled(pwm->hwpwm);
 116         if (is_enabled)
 117                 jz4740_pwm_disable(chip, pwm);
 118
 119         jz4740_timer_set_count(pwm->hwpwm, 0);
 120         jz4740_timer_set_duty(pwm->hwpwm, duty);
 121         jz4740_timer_set_period(pwm->hwpwm, period);
 122
 123         ctrl = JZ_TIMER_CTRL_PRESCALER(prescaler) | JZ_TIMER_CTRL_SRC_EXT |
 124                 JZ_TIMER_CTRL_PWM_ABBRUPT_SHUTDOWN;
 125
 126         jz4740_timer_set_ctrl(pwm->hwpwm, ctrl);
 127
 128         if (is_enabled)
 129                 jz4740_pwm_enable(chip, pwm);
 130
 131         return 0;
 132 }
 133
 134 static int jz4740_pwm_set_polarity(struct pwm_chip *chip,
 135                 struct pwm_device *pwm, enum pwm_polarity polarity)
 136 {
 137         uint32_t ctrl = jz4740_timer_get_ctrl(pwm->pwm);
 138
 139         switch (polarity) {
 140         case PWM_POLARITY_NORMAL:
 141                 ctrl &= ~JZ_TIMER_CTRL_PWM_ACTIVE_LOW;
 142                 break;
 143         case PWM_POLARITY_INVERSED:
 144                 ctrl |= JZ_TIMER_CTRL_PWM_ACTIVE_LOW;
 145                 break;
 146         }
 147
 148         jz4740_timer_set_ctrl(pwm->hwpwm, ctrl);
 149         return 0;
 150 }
 151
 152 static const struct pwm_ops jz4740_pwm_ops = {
 153         .request = jz4740_pwm_request,
 154         .free = jz4740_pwm_free,
 155         .config = jz4740_pwm_config,
 156         .set_polarity = jz4740_pwm_set_polarity,
 157         .enable = jz4740_pwm_enable,
 158         .disable = jz4740_pwm_disable,
 159         .owner = THIS_MODULE,
 160 };
 161
 162 static int jz4740_pwm_probe(struct platform_device *pdev)
 163 {
 164         struct jz4740_pwm_chip *jz4740;
 165
 166         jz4740 = devm_kzalloc(&pdev->dev, sizeof(*jz4740), GFP_KERNEL);
 167         if (!jz4740)
 168                 return -ENOMEM;
 169
 170         jz4740->clk = devm_clk_get(&pdev->dev, "ext");
 171         if (IS_ERR(jz4740->clk))
 172                 return PTR_ERR(jz4740->clk);
 173
 174         jz4740->chip.dev = &pdev->dev;
 175         jz4740->chip.ops = &jz4740_pwm_ops;
 176         jz4740->chip.npwm = NUM_PWM;
 177         jz4740->chip.base = -1;
 178         jz4740->chip.of_xlate = of_pwm_xlate_with_flags;
 179         jz4740->chip.of_pwm_n_cells = 3;
 180
 181         platform_set_drvdata(pdev, jz4740);
 182
 183         return pwmchip_add(&jz4740->chip);
 184 }
 185
 186 static int jz4740_pwm_remove(struct platform_device *pdev)
 187 {
 188         struct jz4740_pwm_chip *jz4740 = platform_get_drvdata(pdev);
 189
 190         return pwmchip_remove(&jz4740->chip);
 191 }
 192
 193 #ifdef CONFIG_OF
 194 static const struct of_device_id jz4740_pwm_dt_ids[] = {
 195         { .compatible = "ingenic,jz4740-pwm", },
 196         { .compatible = "ingenic,jz4770-pwm", },
 197         { .compatible = "ingenic,jz4780-pwm", },
 198         {},
 199 };
 200 MODULE_DEVICE_TABLE(of, jz4740_pwm_dt_ids);
 201 #endif
 202
 203 static struct platform_driver jz4740_pwm_driver = {
 204         .driver = {
 205                 .name = "jz4740-pwm",
 206                 .of_match_table = of_match_ptr(jz4740_pwm_dt_ids),
 207         },
 208         .probe = jz4740_pwm_probe,
 209         .remove = jz4740_pwm_remove,
 210 };
 211 module_platform_driver(jz4740_pwm_driver);
 212
 213 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
 214 MODULE_DESCRIPTION("Ingenic JZ4740 PWM driver");
 215 MODULE_ALIAS("platform:jz4740-pwm");
 216 MODULE_LICENSE("GPL");