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/mod_devicetable.h>
  21 #include <linux/platform_device.h>
  22 #include <linux/slab.h>
  23 #include <linux/clk.h>
  24 #include <linux/err.h>
  25 #include <linux/io.h>
  26 #include <linux/pwm.h>
  27
  28 #include <asm/div64.h>
  29
  30 #define EP93XX_PWMx_TERM_COUNT  0x00
  31 #define EP93XX_PWMx_DUTY_CYCLE  0x04
  32 #define EP93XX_PWMx_ENABLE      0x08
  33 #define EP93XX_PWMx_INVERT      0x0c
  34
  35 struct ep93xx_pwm {
  36         void __iomem *base;
  37         struct clk *clk;
  38 };
  39
  40 static inline struct ep93xx_pwm *to_ep93xx_pwm(struct pwm_chip *chip)
  41 {
  42         return pwmchip_get_drvdata(chip);
  43 }
  44
  45 static int ep93xx_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
  46                             const struct pwm_state *state)
  47 {
  48         int ret;
  49         struct ep93xx_pwm *ep93xx_pwm = to_ep93xx_pwm(chip);
  50         bool enabled = state->enabled;
  51         void __iomem *base = ep93xx_pwm->base;
  52         unsigned long long c;
  53         unsigned long period_cycles;
  54         unsigned long duty_cycles;
  55         unsigned long term;
  56
  57         if (state->polarity != pwm->state.polarity) {
  58                 if (enabled) {
  59                         writew(0x0, ep93xx_pwm->base + EP93XX_PWMx_ENABLE);
  60                         clk_disable_unprepare(ep93xx_pwm->clk);
  61                         enabled = false;
  62                 }
  63
  64                 /*
  65                  * The clock needs to be enabled to access the PWM registers.
  66                  * Polarity can only be changed when the PWM is disabled.
  67                  */
  68                 ret = clk_prepare_enable(ep93xx_pwm->clk);
  69                 if (ret)
  70                         return ret;
  71
  72                 if (state->polarity == PWM_POLARITY_INVERSED)
  73                         writew(0x1, ep93xx_pwm->base + EP93XX_PWMx_INVERT);
  74                 else
  75                         writew(0x0, ep93xx_pwm->base + EP93XX_PWMx_INVERT);
  76
  77                 clk_disable_unprepare(ep93xx_pwm->clk);
  78         }
  79
  80         if (!state->enabled) {
  81                 if (enabled) {
  82                         writew(0x0, ep93xx_pwm->base + EP93XX_PWMx_ENABLE);
  83                         clk_disable_unprepare(ep93xx_pwm->clk);
  84                 }
  85
  86                 return 0;
  87         }
  88
  89         /*
  90          * The clock needs to be enabled to access the PWM registers.
  91          * Configuration can be changed at any time.
  92          */
  93         if (!pwm_is_enabled(pwm)) {
  94                 ret = clk_prepare_enable(ep93xx_pwm->clk);
  95                 if (ret)
  96                         return ret;
  97         }
  98
  99         c = clk_get_rate(ep93xx_pwm->clk);
 100         c *= state->period;
 101         do_div(c, 1000000000);
 102         period_cycles = c;
 103
 104         c = period_cycles;
 105         c *= state->duty_cycle;
 106         do_div(c, state->period);
 107         duty_cycles = c;
 108
 109         if (period_cycles < 0x10000 && duty_cycles < 0x10000) {
 110                 term = readw(base + EP93XX_PWMx_TERM_COUNT);
 111
 112                 /* Order is important if PWM is running */
 113                 if (period_cycles > term) {
 114                         writew(period_cycles, base + EP93XX_PWMx_TERM_COUNT);
 115                         writew(duty_cycles, base + EP93XX_PWMx_DUTY_CYCLE);
 116                 } else {
 117                         writew(duty_cycles, base + EP93XX_PWMx_DUTY_CYCLE);
 118                         writew(period_cycles, base + EP93XX_PWMx_TERM_COUNT);
 119                 }
 120                 ret = 0;
 121         } else {
 122                 ret = -EINVAL;
 123         }
 124
 125         if (!pwm_is_enabled(pwm))
 126                 clk_disable_unprepare(ep93xx_pwm->clk);
 127
 128         if (ret)
 129                 return ret;
 130
 131         if (!enabled) {
 132                 ret = clk_prepare_enable(ep93xx_pwm->clk);
 133                 if (ret)
 134                         return ret;
 135
 136                 writew(0x1, ep93xx_pwm->base + EP93XX_PWMx_ENABLE);
 137         }
 138
 139         return 0;
 140 }
 141
 142 static const struct pwm_ops ep93xx_pwm_ops = {
 143         .apply = ep93xx_pwm_apply,
 144 };
 145
 146 static int ep93xx_pwm_probe(struct platform_device *pdev)
 147 {
 148         struct pwm_chip *chip;
 149         struct ep93xx_pwm *ep93xx_pwm;
 150         int ret;
 151
 152         chip = devm_pwmchip_alloc(&pdev->dev, 1, sizeof(*ep93xx_pwm));
 153         if (IS_ERR(chip))
 154                 return PTR_ERR(chip);
 155         ep93xx_pwm = to_ep93xx_pwm(chip);
 156
 157         ep93xx_pwm->base = devm_platform_ioremap_resource(pdev, 0);
 158         if (IS_ERR(ep93xx_pwm->base))
 159                 return PTR_ERR(ep93xx_pwm->base);
 160
 161         ep93xx_pwm->clk = devm_clk_get(&pdev->dev, "pwm_clk");
 162         if (IS_ERR(ep93xx_pwm->clk))
 163                 return PTR_ERR(ep93xx_pwm->clk);
 164
 165         chip->ops = &ep93xx_pwm_ops;
 166
 167         ret = devm_pwmchip_add(&pdev->dev, chip);
 168         if (ret < 0)
 169                 return ret;
 170
 171         return 0;
 172 }
 173
 174 static const struct of_device_id ep93xx_pwm_of_ids[] = {
 175         { .compatible = "cirrus,ep9301-pwm" },
 176         { /* sentinel */}
 177 };
 178 MODULE_DEVICE_TABLE(of, ep93xx_pwm_of_ids);
 179
 180 static struct platform_driver ep93xx_pwm_driver = {
 181         .driver = {
 182                 .name = "ep93xx-pwm",
 183                 .of_match_table = ep93xx_pwm_of_ids,
 184         },
 185         .probe = ep93xx_pwm_probe,
 186 };
 187 module_platform_driver(ep93xx_pwm_driver);
 188
 189 MODULE_DESCRIPTION("Cirrus Logic EP93xx PWM driver");
 190 MODULE_AUTHOR("Matthieu Crapet <mcrapet@gmail.com>");
 191 MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");
 192 MODULE_ALIAS("platform:ep93xx-pwm");
 193 MODULE_LICENSE("GPL");