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