drivers/pwm/pwm-ep93xx.c

   1 /*
   2  * PWM framework driver for Cirrus Logic EP93xx
   3  *
   4  * Copyright (c) 2009        Matthieu Crapet <mcrapet@gmail.com>
   5  * Copyright (c) 2009, 2013  H Hartley Sweeten <hsweeten@visionengravers.com>
   6  *
   7  * EP9301/02 have only one channel:
   8  *   platform device ep93xx-pwm.1 - PWMOUT1 (EGPIO14)
   9  *
  10  * EP9307 has only one channel:
  11  *   platform device ep93xx-pwm.0 - PWMOUT
  12  *
  13  * EP9312/15 have two channels:
  14  *   platform device ep93xx-pwm.0 - PWMOUT
  15  *   platform device ep93xx-pwm.1 - PWMOUT1 (EGPIO14)
  16  *
  17  * This program is free software; you can redistribute it and/or
  18  * modify it under the terms of the GNU General Public License
  19  * as published by the Free Software Foundation; either version
  20  * 2 of the License, or (at your option) any later version.
  21  *
  22  * This program is distributed in the hope that it will be useful,
  23  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  24  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  25  * GNU General Public License for more details.
  26  */
  27
  28 #include <linux/module.h>
  29 #include <linux/platform_device.h>
  30 #include <linux/slab.h>
  31 #include <linux/clk.h>
  32 #include <linux/err.h>
  33 #include <linux/io.h>
  34 #include <linux/pwm.h>
  35
  36 #include <asm/div64.h>
  37
  38 #include <mach/platform.h>      /* for ep93xx_pwm_{acquire,release}_gpio() */
  39
  40 #define EP93XX_PWMx_TERM_COUNT  0x00
  41 #define EP93XX_PWMx_DUTY_CYCLE  0x04
  42 #define EP93XX_PWMx_ENABLE      0x08
  43 #define EP93XX_PWMx_INVERT      0x0c
  44
  45 struct ep93xx_pwm {
  46         void __iomem *base;
  47         struct clk *clk;
  48         struct pwm_chip chip;
  49 };
  50
  51 static inline struct ep93xx_pwm *to_ep93xx_pwm(struct pwm_chip *chip)
  52 {
  53         return container_of(chip, struct ep93xx_pwm, chip);
  54 }
  55
  56 static int ep93xx_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
  57 {
  58         struct platform_device *pdev = to_platform_device(chip->dev);
  59
  60         return ep93xx_pwm_acquire_gpio(pdev);
  61 }
  62
  63 static void ep93xx_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
  64 {
  65         struct platform_device *pdev = to_platform_device(chip->dev);
  66
  67         ep93xx_pwm_release_gpio(pdev);
  68 }
  69
  70 static int ep93xx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
  71                              int duty_ns, int period_ns)
  72 {
  73         struct ep93xx_pwm *ep93xx_pwm = to_ep93xx_pwm(chip);
  74         void __iomem *base = ep93xx_pwm->base;
  75         unsigned long long c;
  76         unsigned long period_cycles;
  77         unsigned long duty_cycles;
  78         unsigned long term;
  79         int ret = 0;
  80
  81         /*
  82          * The clock needs to be enabled to access the PWM registers.
  83          * Configuration can be changed at any time.
  84          */
  85         if (!test_bit(PWMF_ENABLED, &pwm->flags)) {
  86                 ret = clk_enable(ep93xx_pwm->clk);
  87                 if (ret)
  88                         return ret;
  89         }
  90
  91         c = clk_get_rate(ep93xx_pwm->clk);
  92         c *= period_ns;
  93         do_div(c, 1000000000);
  94         period_cycles = c;
  95
  96         c = period_cycles;
  97         c *= duty_ns;
  98         do_div(c, period_ns);
  99         duty_cycles = c;
 100
 101         if (period_cycles < 0x10000 && duty_cycles < 0x10000) {
 102                 term = readw(base + EP93XX_PWMx_TERM_COUNT);
 103
 104                 /* Order is important if PWM is running */
 105                 if (period_cycles > term) {
 106                         writew(period_cycles, base + EP93XX_PWMx_TERM_COUNT);
 107                         writew(duty_cycles, base + EP93XX_PWMx_DUTY_CYCLE);
 108                 } else {
 109                         writew(duty_cycles, base + EP93XX_PWMx_DUTY_CYCLE);
 110                         writew(period_cycles, base + EP93XX_PWMx_TERM_COUNT);
 111                 }
 112         } else {
 113                 ret = -EINVAL;
 114         }
 115
 116         if (!test_bit(PWMF_ENABLED, &pwm->flags))
 117                 clk_disable(ep93xx_pwm->clk);
 118
 119         return ret;
 120 }
 121
 122 static int ep93xx_pwm_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
 123                                enum pwm_polarity polarity)
 124 {
 125         struct ep93xx_pwm *ep93xx_pwm = to_ep93xx_pwm(chip);
 126         int ret;
 127
 128         /*
 129          * The clock needs to be enabled to access the PWM registers.
 130          * Polarity can only be changed when the PWM is disabled.
 131          */
 132         ret = clk_enable(ep93xx_pwm->clk);
 133         if (ret)
 134                 return ret;
 135
 136         if (polarity == PWM_POLARITY_INVERSED)
 137                 writew(0x1, ep93xx_pwm->base + EP93XX_PWMx_INVERT);
 138         else
 139                 writew(0x0, ep93xx_pwm->base + EP93XX_PWMx_INVERT);
 140
 141         clk_disable(ep93xx_pwm->clk);
 142
 143         return 0;
 144 }
 145
 146 static int ep93xx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 147 {
 148         struct ep93xx_pwm *ep93xx_pwm = to_ep93xx_pwm(chip);
 149         int ret;
 150
 151         ret = clk_enable(ep93xx_pwm->clk);
 152         if (ret)
 153                 return ret;
 154
 155         writew(0x1, ep93xx_pwm->base + EP93XX_PWMx_ENABLE);
 156
 157         return 0;
 158 }
 159
 160 static void ep93xx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 161 {
 162         struct ep93xx_pwm *ep93xx_pwm = to_ep93xx_pwm(chip);
 163
 164         writew(0x0, ep93xx_pwm->base + EP93XX_PWMx_ENABLE);
 165         clk_disable(ep93xx_pwm->clk);
 166 }
 167
 168 static const struct pwm_ops ep93xx_pwm_ops = {
 169         .request = ep93xx_pwm_request,
 170         .free = ep93xx_pwm_free,
 171         .config = ep93xx_pwm_config,
 172         .set_polarity = ep93xx_pwm_polarity,
 173         .enable = ep93xx_pwm_enable,
 174         .disable = ep93xx_pwm_disable,
 175         .owner = THIS_MODULE,
 176 };
 177
 178 static int ep93xx_pwm_probe(struct platform_device *pdev)
 179 {
 180         struct ep93xx_pwm *ep93xx_pwm;
 181         struct resource *res;
 182         int ret;
 183
 184         ep93xx_pwm = devm_kzalloc(&pdev->dev, sizeof(*ep93xx_pwm), GFP_KERNEL);
 185         if (!ep93xx_pwm)
 186                 return -ENOMEM;
 187
 188         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 189         ep93xx_pwm->base = devm_ioremap_resource(&pdev->dev, res);
 190         if (IS_ERR(ep93xx_pwm->base))
 191                 return PTR_ERR(ep93xx_pwm->base);
 192
 193         ep93xx_pwm->clk = devm_clk_get(&pdev->dev, "pwm_clk");
 194         if (IS_ERR(ep93xx_pwm->clk))
 195                 return PTR_ERR(ep93xx_pwm->clk);
 196
 197         ep93xx_pwm->chip.dev = &pdev->dev;
 198         ep93xx_pwm->chip.ops = &ep93xx_pwm_ops;
 199         ep93xx_pwm->chip.base = -1;
 200         ep93xx_pwm->chip.npwm = 1;
 201
 202         ret = pwmchip_add(&ep93xx_pwm->chip);
 203         if (ret < 0)
 204                 return ret;
 205
 206         platform_set_drvdata(pdev, ep93xx_pwm);
 207         return 0;
 208 }
 209
 210 static int ep93xx_pwm_remove(struct platform_device *pdev)
 211 {
 212         struct ep93xx_pwm *ep93xx_pwm = platform_get_drvdata(pdev);
 213
 214         return pwmchip_remove(&ep93xx_pwm->chip);
 215 }
 216
 217 static struct platform_driver ep93xx_pwm_driver = {
 218         .driver = {
 219                 .name = "ep93xx-pwm",
 220         },
 221         .probe = ep93xx_pwm_probe,
 222         .remove = ep93xx_pwm_remove,
 223 };
 224 module_platform_driver(ep93xx_pwm_driver);
 225
 226 MODULE_DESCRIPTION("Cirrus Logic EP93xx PWM driver");
 227 MODULE_AUTHOR("Matthieu Crapet <mcrapet@gmail.com>, "
 228               "H Hartley Sweeten <hsweeten@visionengravers.com>");
 229 MODULE_ALIAS("platform:ep93xx-pwm");
 230 MODULE_LICENSE("GPL");