drivers/misc/ab8500-pwm.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 pwm_device {
  28         struct device *dev;
  29         struct list_head node;
  30         const char *label;
  31         unsigned int pwm_id;
  32 };
  33
  34 static LIST_HEAD(pwm_list);
  35
  36 int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
  37 {
  38         int ret = 0;
  39         unsigned int higher_val, lower_val;
  40         u8 reg;
  41
  42         /*
  43          * get the first 8 bits that are be written to
  44          * AB8500_PWM_OUT_CTRL1_REG[0:7]
  45          */
  46         lower_val = duty_ns & 0x00FF;
  47         /*
  48          * get bits [9:10] that are to be written to
  49          * AB8500_PWM_OUT_CTRL2_REG[0:1]
  50          */
  51         higher_val = ((duty_ns & 0x0300) >> 8);
  52
  53         reg = AB8500_PWM_OUT_CTRL1_REG + ((pwm->pwm_id - 1) * 2);
  54
  55         ret = abx500_set_register_interruptible(pwm->dev, AB8500_MISC,
  56                         reg, (u8)lower_val);
  57         if (ret < 0)
  58                 return ret;
  59         ret = abx500_set_register_interruptible(pwm->dev, AB8500_MISC,
  60                         (reg + 1), (u8)higher_val);
  61
  62         return ret;
  63 }
  64 EXPORT_SYMBOL(pwm_config);
  65
  66 int pwm_enable(struct pwm_device *pwm)
  67 {
  68         int ret;
  69
  70         ret = abx500_mask_and_set_register_interruptible(pwm->dev,
  71                                 AB8500_MISC, AB8500_PWM_OUT_CTRL7_REG,
  72                                 1 << (pwm->pwm_id-1), ENABLE_PWM);
  73         if (ret < 0)
  74                 dev_err(pwm->dev, "%s: Failed to disable PWM, Error %d\n",
  75                                                         pwm->label, ret);
  76         return ret;
  77 }
  78 EXPORT_SYMBOL(pwm_enable);
  79
  80 void pwm_disable(struct pwm_device *pwm)
  81 {
  82         int ret;
  83
  84         ret = abx500_mask_and_set_register_interruptible(pwm->dev,
  85                                 AB8500_MISC, AB8500_PWM_OUT_CTRL7_REG,
  86                                 1 << (pwm->pwm_id-1), DISABLE_PWM);
  87         if (ret < 0)
  88                 dev_err(pwm->dev, "%s: Failed to disable PWM, Error %d\n",
  89                                                         pwm->label, ret);
  90         return;
  91 }
  92 EXPORT_SYMBOL(pwm_disable);
  93
  94 struct pwm_device *pwm_request(int pwm_id, const char *label)
  95 {
  96         struct pwm_device *pwm;
  97
  98         list_for_each_entry(pwm, &pwm_list, node) {
  99                 if (pwm->pwm_id == pwm_id) {
 100                         pwm->label = label;
 101                         pwm->pwm_id = pwm_id;
 102                         return pwm;
 103                 }
 104         }
 105
 106         return ERR_PTR(-ENOENT);
 107 }
 108 EXPORT_SYMBOL(pwm_request);
 109
 110 void pwm_free(struct pwm_device *pwm)
 111 {
 112         pwm_disable(pwm);
 113 }
 114 EXPORT_SYMBOL(pwm_free);
 115
 116 static int __devinit ab8500_pwm_probe(struct platform_device *pdev)
 117 {
 118         struct pwm_device *pwm;
 119         /*
 120          * Nothing to be done in probe, this is required to get the
 121          * device which is required for ab8500 read and write
 122          */
 123         pwm = kzalloc(sizeof(struct pwm_device), GFP_KERNEL);
 124         if (pwm == NULL) {
 125                 dev_err(&pdev->dev, "failed to allocate memory\n");
 126                 return -ENOMEM;
 127         }
 128         pwm->dev = &pdev->dev;
 129         pwm->pwm_id = pdev->id;
 130         list_add_tail(&pwm->node, &pwm_list);
 131         platform_set_drvdata(pdev, pwm);
 132         dev_dbg(pwm->dev, "pwm probe successful\n");
 133         return 0;
 134 }
 135
 136 static int __devexit ab8500_pwm_remove(struct platform_device *pdev)
 137 {
 138         struct pwm_device *pwm = platform_get_drvdata(pdev);
 139         list_del(&pwm->node);
 140         dev_dbg(&pdev->dev, "pwm driver removed\n");
 141         kfree(pwm);
 142         return 0;
 143 }
 144
 145 static const struct of_device_id ab8500_pwm_match[] = {
 146         { .compatible = "stericsson,ab8500-pwm", },
 147         {}
 148 };
 149
 150 static struct platform_driver ab8500_pwm_driver = {
 151         .driver = {
 152                 .name = "ab8500-pwm",
 153                 .owner = THIS_MODULE,
 154                 .of_match_table = ab8500_pwm_match,
 155         },
 156         .probe = ab8500_pwm_probe,
 157         .remove = __devexit_p(ab8500_pwm_remove),
 158 };
 159
 160 static int __init ab8500_pwm_init(void)
 161 {
 162         return platform_driver_register(&ab8500_pwm_driver);
 163 }
 164
 165 static void __exit ab8500_pwm_exit(void)
 166 {
 167         platform_driver_unregister(&ab8500_pwm_driver);
 168 }
 169
 170 subsys_initcall(ab8500_pwm_init);
 171 module_exit(ab8500_pwm_exit);
 172 MODULE_AUTHOR("Arun MURTHY <arun.murthy@stericsson.com>");
 173 MODULE_DESCRIPTION("AB8500 Pulse Width Modulation Driver");
 174 MODULE_ALIAS("platform:ab8500-pwm");
 175 MODULE_LICENSE("GPL v2");