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 };
  40
  41 static inline struct ep93xx_pwm *to_ep93xx_pwm(struct pwm_chip *chip)
  42 {
  43         return pwmchip_get_drvdata(chip);
  44 }
  45
  46 static int ep93xx_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
  47 {
  48         struct platform_device *pdev = to_platform_device(pwmchip_parent(chip));
  49
  50         return ep93xx_pwm_acquire_gpio(pdev);
  51 }
  52
  53 static void ep93xx_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
  54 {
  55         struct platform_device *pdev = to_platform_device(pwmchip_parent(chip));
  56
  57         ep93xx_pwm_release_gpio(pdev);
  58 }
  59
  60 static int ep93xx_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
  61                             const struct pwm_state *state)
  62 {
  63         int ret;
  64         struct ep93xx_pwm *ep93xx_pwm = to_ep93xx_pwm(chip);
  65         bool enabled = state->enabled;
  66         void __iomem *base = ep93xx_pwm->base;
  67         unsigned long long c;
  68         unsigned long period_cycles;
  69         unsigned long duty_cycles;
  70         unsigned long term;
  71
  72         if (state->polarity != pwm->state.polarity) {
  73                 if (enabled) {
  74                         writew(0x0, ep93xx_pwm->base + EP93XX_PWMx_ENABLE);
  75                         clk_disable_unprepare(ep93xx_pwm->clk);
  76                         enabled = false;
  77                 }
  78
  79                 /*
  80                  * The clock needs to be enabled to access the PWM registers.
  81                  * Polarity can only be changed when the PWM is disabled.
  82                  */
  83                 ret = clk_prepare_enable(ep93xx_pwm->clk);
  84                 if (ret)
  85                         return ret;
  86
  87                 if (state->polarity == PWM_POLARITY_INVERSED)
  88                         writew(0x1, ep93xx_pwm->base + EP93XX_PWMx_INVERT);
  89                 else
  90                         writew(0x0, ep93xx_pwm->base + EP93XX_PWMx_INVERT);
  91
  92                 clk_disable_unprepare(ep93xx_pwm->clk);
  93         }
  94
  95         if (!state->enabled) {
  96                 if (enabled) {
  97                         writew(0x0, ep93xx_pwm->base + EP93XX_PWMx_ENABLE);
  98                         clk_disable_unprepare(ep93xx_pwm->clk);
  99                 }
 100
 101                 return 0;
 102         }
 103
 104         /*
 105          * The clock needs to be enabled to access the PWM registers.
 106          * Configuration can be changed at any time.
 107          */
 108         if (!pwm_is_enabled(pwm)) {
 109                 ret = clk_prepare_enable(ep93xx_pwm->clk);
 110                 if (ret)
 111                         return ret;
 112         }
 113
 114         c = clk_get_rate(ep93xx_pwm->clk);
 115         c *= state->period;
 116         do_div(c, 1000000000);
 117         period_cycles = c;
 118
 119         c = period_cycles;
 120         c *= state->duty_cycle;
 121         do_div(c, state->period);
 122         duty_cycles = c;
 123
 124         if (period_cycles < 0x10000 && duty_cycles < 0x10000) {
 125                 term = readw(base + EP93XX_PWMx_TERM_COUNT);
 126
 127                 /* Order is important if PWM is running */
 128                 if (period_cycles > term) {
 129                         writew(period_cycles, base + EP93XX_PWMx_TERM_COUNT);
 130                         writew(duty_cycles, base + EP93XX_PWMx_DUTY_CYCLE);
 131                 } else {
 132                         writew(duty_cycles, base + EP93XX_PWMx_DUTY_CYCLE);
 133                         writew(period_cycles, base + EP93XX_PWMx_TERM_COUNT);
 134                 }
 135                 ret = 0;
 136         } else {
 137                 ret = -EINVAL;
 138         }
 139
 140         if (!pwm_is_enabled(pwm))
 141                 clk_disable_unprepare(ep93xx_pwm->clk);
 142
 143         if (ret)
 144                 return ret;
 145
 146         if (!enabled) {
 147                 ret = clk_prepare_enable(ep93xx_pwm->clk);
 148                 if (ret)
 149                         return ret;
 150
 151                 writew(0x1, ep93xx_pwm->base + EP93XX_PWMx_ENABLE);
 152         }
 153
 154         return 0;
 155 }
 156
 157 static const struct pwm_ops ep93xx_pwm_ops = {
 158         .request = ep93xx_pwm_request,
 159         .free = ep93xx_pwm_free,
 160         .apply = ep93xx_pwm_apply,
 161 };
 162
 163 static int ep93xx_pwm_probe(struct platform_device *pdev)
 164 {
 165         struct pwm_chip *chip;
 166         struct ep93xx_pwm *ep93xx_pwm;
 167         int ret;
 168
 169         chip = devm_pwmchip_alloc(&pdev->dev, 1, sizeof(*ep93xx_pwm));
 170         if (IS_ERR(chip))
 171                 return PTR_ERR(chip);
 172         ep93xx_pwm = to_ep93xx_pwm(chip);
 173
 174         ep93xx_pwm->base = devm_platform_ioremap_resource(pdev, 0);
 175         if (IS_ERR(ep93xx_pwm->base))
 176                 return PTR_ERR(ep93xx_pwm->base);
 177
 178         ep93xx_pwm->clk = devm_clk_get(&pdev->dev, "pwm_clk");
 179         if (IS_ERR(ep93xx_pwm->clk))
 180                 return PTR_ERR(ep93xx_pwm->clk);
 181
 182         chip->ops = &ep93xx_pwm_ops;
 183
 184         ret = devm_pwmchip_add(&pdev->dev, chip);
 185         if (ret < 0)
 186                 return ret;
 187
 188         return 0;
 189 }
 190
 191 static struct platform_driver ep93xx_pwm_driver = {
 192         .driver = {
 193                 .name = "ep93xx-pwm",
 194         },
 195         .probe = ep93xx_pwm_probe,
 196 };
 197 module_platform_driver(ep93xx_pwm_driver);
 198
 199 MODULE_DESCRIPTION("Cirrus Logic EP93xx PWM driver");
 200 MODULE_AUTHOR("Matthieu Crapet <mcrapet@gmail.com>");
 201 MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");
 202 MODULE_ALIAS("platform:ep93xx-pwm");
 203 MODULE_LICENSE("GPL");