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/slab.h>
  15 #include <linux/w1-gpio.h>
  16
  17 #include "../w1.h"
  18 #include "../w1_int.h"
  19
  20 #include <asm/gpio.h>
  21
  22 static void w1_gpio_write_bit_dir(void *data, u8 bit)
  23 {
  24         struct w1_gpio_platform_data *pdata = data;
  25
  26         if (bit)
  27                 gpio_direction_input(pdata->pin);
  28         else
  29                 gpio_direction_output(pdata->pin, 0);
  30 }
  31
  32 static void w1_gpio_write_bit_val(void *data, u8 bit)
  33 {
  34         struct w1_gpio_platform_data *pdata = data;
  35
  36         gpio_set_value(pdata->pin, bit);
  37 }
  38
  39 static u8 w1_gpio_read_bit(void *data)
  40 {
  41         struct w1_gpio_platform_data *pdata = data;
  42
  43         return gpio_get_value(pdata->pin) ? 1 : 0;
  44 }
  45
  46 static int __init w1_gpio_probe(struct platform_device *pdev)
  47 {
  48         struct w1_bus_master *master;
  49         struct w1_gpio_platform_data *pdata = pdev->dev.platform_data;
  50         int err;
  51
  52         if (!pdata)
  53                 return -ENXIO;
  54
  55         master = kzalloc(sizeof(struct w1_bus_master), GFP_KERNEL);
  56         if (!master)
  57                 return -ENOMEM;
  58
  59         err = gpio_request(pdata->pin, "w1");
  60         if (err)
  61                 goto free_master;
  62
  63         master->data = pdata;
  64         master->read_bit = w1_gpio_read_bit;
  65
  66         if (pdata->is_open_drain) {
  67                 gpio_direction_output(pdata->pin, 1);
  68                 master->write_bit = w1_gpio_write_bit_val;
  69         } else {
  70                 gpio_direction_input(pdata->pin);
  71                 master->write_bit = w1_gpio_write_bit_dir;
  72         }
  73
  74         err = w1_add_master_device(master);
  75         if (err)
  76                 goto free_gpio;
  77
  78         if (pdata->enable_external_pullup)
  79                 pdata->enable_external_pullup(1);
  80
  81         platform_set_drvdata(pdev, master);
  82
  83         return 0;
  84
  85  free_gpio:
  86         gpio_free(pdata->pin);
  87  free_master:
  88         kfree(master);
  89
  90         return err;
  91 }
  92
  93 static int __exit w1_gpio_remove(struct platform_device *pdev)
  94 {
  95         struct w1_bus_master *master = platform_get_drvdata(pdev);
  96         struct w1_gpio_platform_data *pdata = pdev->dev.platform_data;
  97
  98         if (pdata->enable_external_pullup)
  99                 pdata->enable_external_pullup(0);
 100
 101         w1_remove_master_device(master);
 102         gpio_free(pdata->pin);
 103         kfree(master);
 104
 105         return 0;
 106 }
 107
 108 #ifdef CONFIG_PM
 109
 110 static int w1_gpio_suspend(struct platform_device *pdev, pm_message_t state)
 111 {
 112         struct w1_gpio_platform_data *pdata = pdev->dev.platform_data;
 113
 114         if (pdata->enable_external_pullup)
 115                 pdata->enable_external_pullup(0);
 116
 117         return 0;
 118 }
 119
 120 static int w1_gpio_resume(struct platform_device *pdev)
 121 {
 122         struct w1_gpio_platform_data *pdata = pdev->dev.platform_data;
 123
 124         if (pdata->enable_external_pullup)
 125                 pdata->enable_external_pullup(1);
 126
 127         return 0;
 128 }
 129
 130 #else
 131 #define w1_gpio_suspend NULL
 132 #define w1_gpio_resume  NULL
 133 #endif
 134
 135 static struct platform_driver w1_gpio_driver = {
 136         .driver = {
 137                 .name   = "w1-gpio",
 138                 .owner  = THIS_MODULE,
 139         },
 140         .remove = __exit_p(w1_gpio_remove),
 141         .suspend = w1_gpio_suspend,
 142         .resume = w1_gpio_resume,
 143 };
 144
 145 static int __init w1_gpio_init(void)
 146 {
 147         return platform_driver_probe(&w1_gpio_driver, w1_gpio_probe);
 148 }
 149
 150 static void __exit w1_gpio_exit(void)
 151 {
 152         platform_driver_unregister(&w1_gpio_driver);
 153 }
 154
 155 module_init(w1_gpio_init);
 156 module_exit(w1_gpio_exit);
 157
 158 MODULE_DESCRIPTION("GPIO w1 bus master driver");
 159 MODULE_AUTHOR("Ville Syrjala <syrjala@sci.fi>");
 160 MODULE_LICENSE("GPL");