drivers/pwm/pwm-ab8500.c

   1 /*
   2  * Copyright (C) ST-Ericsson SA 2010
   3  *
   4  * Author: Arun R Murthy <arun.murthy@stericsson.com>
   5  * License terms: GNU General Public License (GPL) version 2
   6  */
   7 #include <linux/err.h>
   8 #include <linux/platform_device.h>
   9 #include <linux/slab.h>
  10 #include <linux/pwm.h>
  11 #include <linux/mfd/abx500.h>
  12 #include <linux/mfd/abx500/ab8500.h>
  13 #include <linux/module.h>
  14
  15 /*
  16  * PWM Out generators
  17  * Bank: 0x10
  18  */
  19 #define AB8500_PWM_OUT_CTRL1_REG        0x60
  20 #define AB8500_PWM_OUT_CTRL2_REG        0x61
  21 #define AB8500_PWM_OUT_CTRL7_REG        0x66
  22
  23 /* backlight driver constants */
  24 #define ENABLE_PWM                      1
  25 #define DISABLE_PWM                     0
  26
  27 struct ab8500_pwm_chip {
  28         struct pwm_chip chip;
  29 };
  30
  31 static int ab8500_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
  32                              int duty_ns, int period_ns)
  33 {
  34         int ret = 0;
  35         unsigned int higher_val, lower_val;
  36         u8 reg;
  37
  38         /*
  39          * get the first 8 bits that are be written to
  40          * AB8500_PWM_OUT_CTRL1_REG[0:7]
  41          */
  42         lower_val = duty_ns & 0x00FF;
  43         /*
  44          * get bits [9:10] that are to be written to
  45          * AB8500_PWM_OUT_CTRL2_REG[0:1]
  46          */
  47         higher_val = ((duty_ns & 0x0300) >> 8);
  48
  49         reg = AB8500_PWM_OUT_CTRL1_REG + ((chip->base - 1) * 2);
  50
  51         ret = abx500_set_register_interruptible(chip->dev, AB8500_MISC,
  52                         reg, (u8)lower_val);
  53         if (ret < 0)
  54                 return ret;
  55         ret = abx500_set_register_interruptible(chip->dev, AB8500_MISC,
  56                         (reg + 1), (u8)higher_val);
  57
  58         return ret;
  59 }
  60
  61 static int ab8500_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
  62 {
  63         int ret;
  64
  65         ret = abx500_mask_and_set_register_interruptible(chip->dev,
  66                                 AB8500_MISC, AB8500_PWM_OUT_CTRL7_REG,
  67                                 1 << (chip->base - 1), ENABLE_PWM);
  68         if (ret < 0)
  69                 dev_err(chip->dev, "%s: Failed to enable PWM, Error %d\n",
  70                                                         pwm->label, ret);
  71         return ret;
  72 }
  73
  74 static void ab8500_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
  75 {
  76         int ret;
  77
  78         ret = abx500_mask_and_set_register_interruptible(chip->dev,
  79                                 AB8500_MISC, AB8500_PWM_OUT_CTRL7_REG,
  80                                 1 << (chip->base - 1), DISABLE_PWM);
  81         if (ret < 0)
  82                 dev_err(chip->dev, "%s: Failed to disable PWM, Error %d\n",
  83                                                         pwm->label, ret);
  84         return;
  85 }
  86
  87 static const struct pwm_ops ab8500_pwm_ops = {
  88         .config = ab8500_pwm_config,
  89         .enable = ab8500_pwm_enable,
  90         .disable = ab8500_pwm_disable,
  91         .owner = THIS_MODULE,
  92 };
  93
  94 static int ab8500_pwm_probe(struct platform_device *pdev)
  95 {
  96         struct ab8500_pwm_chip *ab8500;
  97         int err;
  98
  99         /*
 100          * Nothing to be done in probe, this is required to get the
 101          * device which is required for ab8500 read and write
 102          */
 103         ab8500 = devm_kzalloc(&pdev->dev, sizeof(*ab8500), GFP_KERNEL);
 104         if (ab8500 == NULL) {
 105                 dev_err(&pdev->dev, "failed to allocate memory\n");
 106                 return -ENOMEM;
 107         }
 108
 109         ab8500->chip.dev = &pdev->dev;
 110         ab8500->chip.ops = &ab8500_pwm_ops;
 111         ab8500->chip.base = pdev->id;
 112         ab8500->chip.npwm = 1;
 113
 114         err = pwmchip_add(&ab8500->chip);
 115         if (err < 0)
 116                 return err;
 117
 118         dev_dbg(&pdev->dev, "pwm probe successful\n");
 119         platform_set_drvdata(pdev, ab8500);
 120
 121         return 0;
 122 }
 123
 124 static int ab8500_pwm_remove(struct platform_device *pdev)
 125 {
 126         struct ab8500_pwm_chip *ab8500 = platform_get_drvdata(pdev);
 127         int err;
 128
 129         err = pwmchip_remove(&ab8500->chip);
 130         if (err < 0)
 131                 return err;
 132
 133         dev_dbg(&pdev->dev, "pwm driver removed\n");
 134
 135         return 0;
 136 }
 137
 138 static struct platform_driver ab8500_pwm_driver = {
 139         .driver = {
 140                 .name = "ab8500-pwm",
 141                 .owner = THIS_MODULE,
 142         },
 143         .probe = ab8500_pwm_probe,
 144         .remove = ab8500_pwm_remove,
 145 };
 146 module_platform_driver(ab8500_pwm_driver);
 147
 148 MODULE_AUTHOR("Arun MURTHY <arun.murthy@stericsson.com>");
 149 MODULE_DESCRIPTION("AB8500 Pulse Width Modulation Driver");
 150 MODULE_ALIAS("platform:ab8500-pwm");
 151 MODULE_LICENSE("GPL v2");