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) ? 1 : 0;
  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         if (pdata->enable_external_pullup)
  78                 pdata->enable_external_pullup(1);
  79
  80         platform_set_drvdata(pdev, master);
  81
  82         return 0;
  83
  84  free_gpio:
  85         gpio_free(pdata->pin);
  86  free_master:
  87         kfree(master);
  88
  89         return err;
  90 }
  91
  92 static int __exit w1_gpio_remove(struct platform_device *pdev)
  93 {
  94         struct w1_bus_master *master = platform_get_drvdata(pdev);
  95         struct w1_gpio_platform_data *pdata = pdev->dev.platform_data;
  96
  97         if (pdata->enable_external_pullup)
  98                 pdata->enable_external_pullup(0);
  99
 100         w1_remove_master_device(master);
 101         gpio_free(pdata->pin);
 102         kfree(master);
 103
 104         return 0;
 105 }
 106
 107 #ifdef CONFIG_PM
 108
 109 static int w1_gpio_suspend(struct platform_device *pdev, pm_message_t state)
 110 {
 111         struct w1_gpio_platform_data *pdata = pdev->dev.platform_data;
 112
 113         if (pdata->enable_external_pullup)
 114                 pdata->enable_external_pullup(0);
 115
 116         return 0;
 117 }
 118
 119 static int w1_gpio_resume(struct platform_device *pdev)
 120 {
 121         struct w1_gpio_platform_data *pdata = pdev->dev.platform_data;
 122
 123         if (pdata->enable_external_pullup)
 124                 pdata->enable_external_pullup(1);
 125
 126         return 0;
 127 }
 128
 129 #else
 130 #define w1_gpio_suspend NULL
 131 #define w1_gpio_resume  NULL
 132 #endif
 133
 134 static struct platform_driver w1_gpio_driver = {
 135         .driver = {
 136                 .name   = "w1-gpio",
 137                 .owner  = THIS_MODULE,
 138         },
 139         .remove = __exit_p(w1_gpio_remove),
 140         .suspend = w1_gpio_suspend,
 141         .resume = w1_gpio_resume,
 142 };
 143
 144 static int __init w1_gpio_init(void)
 145 {
 146         return platform_driver_probe(&w1_gpio_driver, w1_gpio_probe);
 147 }
 148
 149 static void __exit w1_gpio_exit(void)
 150 {
 151         platform_driver_unregister(&w1_gpio_driver);
 152 }
 153
 154 module_init(w1_gpio_init);
 155 module_exit(w1_gpio_exit);
 156
 157 MODULE_DESCRIPTION("GPIO w1 bus master driver");
 158 MODULE_AUTHOR("Ville Syrjala <syrjala@sci.fi>");
 159 MODULE_LICENSE("GPL");