drivers/w1/masters/w1-gpio.c

   1 /*
   2  * w1-gpio - GPIO w1 bus master driver
   3  *
   4  * Copyright (C) 2007 Ville Syrjala <syrjala@sci.fi>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2
   8  * as published by the Free Software Foundation.
   9  */
  10
  11 #include <linux/init.h>
  12 #include <linux/module.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/w1-gpio.h>
  15
  16 #include "../w1.h"
  17 #include "../w1_int.h"
  18
  19 #include <asm/gpio.h>
  20
  21 static void w1_gpio_write_bit_dir(void *data, u8 bit)
  22 {
  23         struct w1_gpio_platform_data *pdata = data;
  24
  25         if (bit)
  26                 gpio_direction_input(pdata->pin);
  27         else
  28                 gpio_direction_output(pdata->pin, 0);
  29 }
  30
  31 static void w1_gpio_write_bit_val(void *data, u8 bit)
  32 {
  33         struct w1_gpio_platform_data *pdata = data;
  34
  35         gpio_set_value(pdata->pin, bit);
  36 }
  37
  38 static u8 w1_gpio_read_bit(void *data)
  39 {
  40         struct w1_gpio_platform_data *pdata = data;
  41
  42         return gpio_get_value(pdata->pin);
  43 }
  44
  45 static int __init w1_gpio_probe(struct platform_device *pdev)
  46 {
  47         struct w1_bus_master *master;
  48         struct w1_gpio_platform_data *pdata = pdev->dev.platform_data;
  49         int err;
  50
  51         if (!pdata)
  52                 return -ENXIO;
  53
  54         master = kzalloc(sizeof(struct w1_bus_master), GFP_KERNEL);
  55         if (!master)
  56                 return -ENOMEM;
  57
  58         err = gpio_request(pdata->pin, "w1");
  59         if (err)
  60                 goto free_master;
  61
  62         master->data = pdata;
  63         master->read_bit = w1_gpio_read_bit;
  64
  65         if (pdata->is_open_drain) {
  66                 gpio_direction_output(pdata->pin, 1);
  67                 master->write_bit = w1_gpio_write_bit_val;
  68         } else {
  69                 gpio_direction_input(pdata->pin);
  70                 master->write_bit = w1_gpio_write_bit_dir;
  71         }
  72
  73         err = w1_add_master_device(master);
  74         if (err)
  75                 goto free_gpio;
  76
  77         platform_set_drvdata(pdev, master);
  78
  79         return 0;
  80
  81  free_gpio:
  82         gpio_free(pdata->pin);
  83  free_master:
  84         kfree(master);
  85
  86         return err;
  87 }
  88
  89 static int __exit w1_gpio_remove(struct platform_device *pdev)
  90 {
  91         struct w1_bus_master *master = platform_get_drvdata(pdev);
  92         struct w1_gpio_platform_data *pdata = pdev->dev.platform_data;
  93
  94         w1_remove_master_device(master);
  95         gpio_free(pdata->pin);
  96         kfree(master);
  97
  98         return 0;
  99 }
 100
 101 static struct platform_driver w1_gpio_driver = {
 102         .driver = {
 103                 .name   = "w1-gpio",
 104                 .owner  = THIS_MODULE,
 105         },
 106         .remove = __exit_p(w1_gpio_remove),
 107 };
 108
 109 static int __init w1_gpio_init(void)
 110 {
 111         return platform_driver_probe(&w1_gpio_driver, w1_gpio_probe);
 112 }
 113
 114 static void __exit w1_gpio_exit(void)
 115 {
 116         platform_driver_unregister(&w1_gpio_driver);
 117 }
 118
 119 module_init(w1_gpio_init);
 120 module_exit(w1_gpio_exit);
 121
 122 MODULE_DESCRIPTION("GPIO w1 bus master driver");
 123 MODULE_AUTHOR("Ville Syrjala <syrjala@sci.fi>");
 124 MODULE_LICENSE("GPL");