drivers/pwm/pwm-ep93xx.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * PWM framework driver for Cirrus Logic EP93xx
   4  *
   5  * Copyright (c) 2009        Matthieu Crapet <mcrapet@gmail.com>
   6  * Copyright (c) 2009, 2013  H Hartley Sweeten <hsweeten@visionengravers.com>
   7  *
   8  * EP9301/02 have only one channel:
   9  *   platform device ep93xx-pwm.1 - PWMOUT1 (EGPIO14)
  10  *
  11  * EP9307 has only one channel:
  12  *   platform device ep93xx-pwm.0 - PWMOUT
  13  *
  14  * EP9312/15 have two channels:
  15  *   platform device ep93xx-pwm.0 - PWMOUT
  16  *   platform device ep93xx-pwm.1 - PWMOUT1 (EGPIO14)
  17  */
  18
  19 #include <linux/module.h>
  20 #include <linux/platform_device.h>
  21 #include <linux/slab.h>
  22 #include <linux/clk.h>
  23 #include <linux/err.h>
  24 #include <linux/io.h>
  25 #include <linux/pwm.h>
  26
  27 #include <asm/div64.h>
  28
  29 #include <linux/soc/cirrus/ep93xx.h>    /* for ep93xx_pwm_{acquire,release}_gpio() */
  30
  31 #define EP93XX_PWMx_TERM_COUNT  0x00
  32 #define EP93XX_PWMx_DUTY_CYCLE  0x04
  33 #define EP93XX_PWMx_ENABLE      0x08
  34 #define EP93XX_PWMx_INVERT      0x0c
  35
  36 struct ep93xx_pwm {
  37         void __iomem *base;
  38         struct clk *clk;
  39         struct pwm_chip chip;
  40 };
  41
  42 static inline struct ep93xx_pwm *to_ep93xx_pwm(struct pwm_chip *chip)
  43 {
  44         return container_of(chip, struct ep93xx_pwm, chip);
  45 }
  46
  47 static int ep93xx_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
  48 {
  49         struct platform_device *pdev = to_platform_device(chip->dev);
  50
  51         return ep93xx_pwm_acquire_gpio(pdev);
  52 }
  53
  54 static void ep93xx_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
  55 {
  56         struct platform_device *pdev = to_platform_device(chip->dev);
  57
  58         ep93xx_pwm_release_gpio(pdev);
  59 }
  60
  61 static int ep93xx_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
  62                             const struct pwm_state *state)
  63 {
  64         int ret;
  65         struct ep93xx_pwm *ep93xx_pwm = to_ep93xx_pwm(chip);
  66         bool enabled = state->enabled;
  67
  68         if (state->polarity != pwm->state.polarity) {
  69                 if (enabled) {
  70                         writew(0x0, ep93xx_pwm->base + EP93XX_PWMx_ENABLE);
  71                         clk_disable_unprepare(ep93xx_pwm->clk);
  72                         enabled = false;
  73                 }
  74
  75                 /*
  76                  * The clock needs to be enabled to access the PWM registers.
  77                  * Polarity can only be changed when the PWM is disabled.
  78                  */
  79                 ret = clk_prepare_enable(ep93xx_pwm->clk);
  80                 if (ret)
  81                         return ret;
  82
  83                 if (state->polarity == PWM_POLARITY_INVERSED)
  84                         writew(0x1, ep93xx_pwm->base + EP93XX_PWMx_INVERT);
  85                 else
  86                         writew(0x0, ep93xx_pwm->base + EP93XX_PWMx_INVERT);
  87
  88                 clk_disable_unprepare(ep93xx_pwm->clk);
  89         }
  90
  91         if (!state->enabled) {
  92                 if (enabled) {
  93                         writew(0x0, ep93xx_pwm->base + EP93XX_PWMx_ENABLE);
  94                         clk_disable_unprepare(ep93xx_pwm->clk);
  95                 }
  96
  97                 return 0;
  98         }
  99
 100         if (state->period != pwm->state.period ||
 101             state->duty_cycle != pwm->state.duty_cycle) {
 102                 struct ep93xx_pwm *ep93xx_pwm = to_ep93xx_pwm(chip);
 103                 void __iomem *base = ep93xx_pwm->base;
 104                 unsigned long long c;
 105                 unsigned long period_cycles;
 106                 unsigned long duty_cycles;
 107                 unsigned long term;
 108
 109                 /*
 110                  * The clock needs to be enabled to access the PWM registers.
 111                  * Configuration can be changed at any time.
 112                  */
 113                 if (!pwm_is_enabled(pwm)) {
 114                         ret = clk_prepare_enable(ep93xx_pwm->clk);
 115                         if (ret)
 116                                 return ret;
 117                 }
 118
 119                 c = clk_get_rate(ep93xx_pwm->clk);
 120                 c *= state->period;
 121                 do_div(c, 1000000000);
 122                 period_cycles = c;
 123
 124                 c = period_cycles;
 125                 c *= state->duty_cycle;
 126                 do_div(c, state->period);
 127                 duty_cycles = c;
 128
 129                 if (period_cycles < 0x10000 && duty_cycles < 0x10000) {
 130                         term = readw(base + EP93XX_PWMx_TERM_COUNT);
 131
 132                         /* Order is important if PWM is running */
 133                         if (period_cycles > term) {
 134                                 writew(period_cycles, base + EP93XX_PWMx_TERM_COUNT);
 135                                 writew(duty_cycles, base + EP93XX_PWMx_DUTY_CYCLE);
 136                         } else {
 137                                 writew(duty_cycles, base + EP93XX_PWMx_DUTY_CYCLE);
 138                                 writew(period_cycles, base + EP93XX_PWMx_TERM_COUNT);
 139                         }
 140                         ret = 0;
 141                 } else {
 142                         ret = -EINVAL;
 143                 }
 144
 145                 if (!pwm_is_enabled(pwm))
 146                         clk_disable_unprepare(ep93xx_pwm->clk);
 147
 148                 if (ret)
 149                         return ret;
 150         }
 151
 152         if (!enabled) {
 153                 ret = clk_prepare_enable(ep93xx_pwm->clk);
 154                 if (ret)
 155                         return ret;
 156
 157                 writew(0x1, ep93xx_pwm->base + EP93XX_PWMx_ENABLE);
 158         }
 159
 160         return 0;
 161 }
 162
 163 static const struct pwm_ops ep93xx_pwm_ops = {
 164         .request = ep93xx_pwm_request,
 165         .free = ep93xx_pwm_free,
 166         .apply = ep93xx_pwm_apply,
 167         .owner = THIS_MODULE,
 168 };
 169
 170 static int ep93xx_pwm_probe(struct platform_device *pdev)
 171 {
 172         struct ep93xx_pwm *ep93xx_pwm;
 173         int ret;
 174
 175         ep93xx_pwm = devm_kzalloc(&pdev->dev, sizeof(*ep93xx_pwm), GFP_KERNEL);
 176         if (!ep93xx_pwm)
 177                 return -ENOMEM;
 178
 179         ep93xx_pwm->base = devm_platform_ioremap_resource(pdev, 0);
 180         if (IS_ERR(ep93xx_pwm->base))
 181                 return PTR_ERR(ep93xx_pwm->base);
 182
 183         ep93xx_pwm->clk = devm_clk_get(&pdev->dev, "pwm_clk");
 184         if (IS_ERR(ep93xx_pwm->clk))
 185                 return PTR_ERR(ep93xx_pwm->clk);
 186
 187         ep93xx_pwm->chip.dev = &pdev->dev;
 188         ep93xx_pwm->chip.ops = &ep93xx_pwm_ops;
 189         ep93xx_pwm->chip.npwm = 1;
 190
 191         ret = pwmchip_add(&ep93xx_pwm->chip);
 192         if (ret < 0)
 193                 return ret;
 194
 195         platform_set_drvdata(pdev, ep93xx_pwm);
 196         return 0;
 197 }
 198
 199 static int ep93xx_pwm_remove(struct platform_device *pdev)
 200 {
 201         struct ep93xx_pwm *ep93xx_pwm = platform_get_drvdata(pdev);
 202
 203         return pwmchip_remove(&ep93xx_pwm->chip);
 204 }
 205
 206 static struct platform_driver ep93xx_pwm_driver = {
 207         .driver = {
 208                 .name = "ep93xx-pwm",
 209         },
 210         .probe = ep93xx_pwm_probe,
 211         .remove = ep93xx_pwm_remove,
 212 };
 213 module_platform_driver(ep93xx_pwm_driver);
 214
 215 MODULE_DESCRIPTION("Cirrus Logic EP93xx PWM driver");
 216 MODULE_AUTHOR("Matthieu Crapet <mcrapet@gmail.com>");
 217 MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");
 218 MODULE_ALIAS("platform:ep93xx-pwm");
 219 MODULE_LICENSE("GPL");