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Linux/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");
152 

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