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 #include <linux/gpio.h>
  17 #include <linux/of_platform.h>
  18 #include <linux/of_gpio.h>
  19 #include <linux/err.h>
  20 #include <linux/of.h>
  21 #include <linux/delay.h>
  22
  23 #include "../w1.h"
  24 #include "../w1_int.h"
  25
  26 static u8 w1_gpio_set_pullup(void *data, int delay)
  27 {
  28         struct w1_gpio_platform_data *pdata = data;
  29
  30         if (delay) {
  31                 pdata->pullup_duration = delay;
  32         } else {
  33                 if (pdata->pullup_duration) {
  34                         gpio_direction_output(pdata->pin, 1);
  35
  36                         msleep(pdata->pullup_duration);
  37
  38                         gpio_direction_input(pdata->pin);
  39                 }
  40                 pdata->pullup_duration = 0;
  41         }
  42
  43         return 0;
  44 }
  45
  46 static void w1_gpio_write_bit_dir(void *data, u8 bit)
  47 {
  48         struct w1_gpio_platform_data *pdata = data;
  49
  50         if (bit)
  51                 gpio_direction_input(pdata->pin);
  52         else
  53                 gpio_direction_output(pdata->pin, 0);
  54 }
  55
  56 static void w1_gpio_write_bit_val(void *data, u8 bit)
  57 {
  58         struct w1_gpio_platform_data *pdata = data;
  59
  60         gpio_set_value(pdata->pin, bit);
  61 }
  62
  63 static u8 w1_gpio_read_bit(void *data)
  64 {
  65         struct w1_gpio_platform_data *pdata = data;
  66
  67         return gpio_get_value(pdata->pin) ? 1 : 0;
  68 }
  69
  70 #if defined(CONFIG_OF)
  71 static struct of_device_id w1_gpio_dt_ids[] = {
  72         { .compatible = "w1-gpio" },
  73         {}
  74 };
  75 MODULE_DEVICE_TABLE(of, w1_gpio_dt_ids);
  76 #endif
  77
  78 static int w1_gpio_probe_dt(struct platform_device *pdev)
  79 {
  80         struct w1_gpio_platform_data *pdata = dev_get_platdata(&pdev->dev);
  81         struct device_node *np = pdev->dev.of_node;
  82         int gpio;
  83
  84         pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
  85         if (!pdata)
  86                 return -ENOMEM;
  87
  88         if (of_get_property(np, "linux,open-drain", NULL))
  89                 pdata->is_open_drain = 1;
  90
  91         gpio = of_get_gpio(np, 0);
  92         if (gpio < 0) {
  93                 if (gpio != -EPROBE_DEFER)
  94                         dev_err(&pdev->dev,
  95                                         "Failed to parse gpio property for data pin (%d)\n",
  96                                         gpio);
  97
  98                 return gpio;
  99         }
 100         pdata->pin = gpio;
 101
 102         gpio = of_get_gpio(np, 1);
 103         if (gpio == -EPROBE_DEFER)
 104                 return gpio;
 105         /* ignore other errors as the pullup gpio is optional */
 106         pdata->ext_pullup_enable_pin = gpio;
 107
 108         pdev->dev.platform_data = pdata;
 109
 110         return 0;
 111 }
 112
 113 static int w1_gpio_probe(struct platform_device *pdev)
 114 {
 115         struct w1_bus_master *master;
 116         struct w1_gpio_platform_data *pdata;
 117         int err;
 118
 119         if (of_have_populated_dt()) {
 120                 err = w1_gpio_probe_dt(pdev);
 121                 if (err < 0)
 122                         return err;
 123         }
 124
 125         pdata = dev_get_platdata(&pdev->dev);
 126
 127         if (!pdata) {
 128                 dev_err(&pdev->dev, "No configuration data\n");
 129                 return -ENXIO;
 130         }
 131
 132         master = devm_kzalloc(&pdev->dev, sizeof(struct w1_bus_master),
 133                         GFP_KERNEL);
 134         if (!master) {
 135                 dev_err(&pdev->dev, "Out of memory\n");
 136                 return -ENOMEM;
 137         }
 138
 139         err = devm_gpio_request(&pdev->dev, pdata->pin, "w1");
 140         if (err) {
 141                 dev_err(&pdev->dev, "gpio_request (pin) failed\n");
 142                 return err;
 143         }
 144
 145         if (gpio_is_valid(pdata->ext_pullup_enable_pin)) {
 146                 err = devm_gpio_request_one(&pdev->dev,
 147                                 pdata->ext_pullup_enable_pin, GPIOF_INIT_LOW,
 148                                 "w1 pullup");
 149                 if (err < 0) {
 150                         dev_err(&pdev->dev, "gpio_request_one "
 151                                         "(ext_pullup_enable_pin) failed\n");
 152                         return err;
 153                 }
 154         }
 155
 156         master->data = pdata;
 157         master->read_bit = w1_gpio_read_bit;
 158
 159         if (pdata->is_open_drain) {
 160                 gpio_direction_output(pdata->pin, 1);
 161                 master->write_bit = w1_gpio_write_bit_val;
 162         } else {
 163                 gpio_direction_input(pdata->pin);
 164                 master->write_bit = w1_gpio_write_bit_dir;
 165                 master->set_pullup = w1_gpio_set_pullup;
 166         }
 167
 168         err = w1_add_master_device(master);
 169         if (err) {
 170                 dev_err(&pdev->dev, "w1_add_master device failed\n");
 171                 return err;
 172         }
 173
 174         if (pdata->enable_external_pullup)
 175                 pdata->enable_external_pullup(1);
 176
 177         if (gpio_is_valid(pdata->ext_pullup_enable_pin))
 178                 gpio_set_value(pdata->ext_pullup_enable_pin, 1);
 179
 180         platform_set_drvdata(pdev, master);
 181
 182         return 0;
 183 }
 184
 185 static int w1_gpio_remove(struct platform_device *pdev)
 186 {
 187         struct w1_bus_master *master = platform_get_drvdata(pdev);
 188         struct w1_gpio_platform_data *pdata = dev_get_platdata(&pdev->dev);
 189
 190         if (pdata->enable_external_pullup)
 191                 pdata->enable_external_pullup(0);
 192
 193         if (gpio_is_valid(pdata->ext_pullup_enable_pin))
 194                 gpio_set_value(pdata->ext_pullup_enable_pin, 0);
 195
 196         w1_remove_master_device(master);
 197
 198         return 0;
 199 }
 200
 201 #ifdef CONFIG_PM
 202
 203 static int w1_gpio_suspend(struct platform_device *pdev, pm_message_t state)
 204 {
 205         struct w1_gpio_platform_data *pdata = dev_get_platdata(&pdev->dev);
 206
 207         if (pdata->enable_external_pullup)
 208                 pdata->enable_external_pullup(0);
 209
 210         return 0;
 211 }
 212
 213 static int w1_gpio_resume(struct platform_device *pdev)
 214 {
 215         struct w1_gpio_platform_data *pdata = dev_get_platdata(&pdev->dev);
 216
 217         if (pdata->enable_external_pullup)
 218                 pdata->enable_external_pullup(1);
 219
 220         return 0;
 221 }
 222
 223 #else
 224 #define w1_gpio_suspend NULL
 225 #define w1_gpio_resume  NULL
 226 #endif
 227
 228 static struct platform_driver w1_gpio_driver = {
 229         .driver = {
 230                 .name   = "w1-gpio",
 231                 .owner  = THIS_MODULE,
 232                 .of_match_table = of_match_ptr(w1_gpio_dt_ids),
 233         },
 234         .probe = w1_gpio_probe,
 235         .remove = w1_gpio_remove,
 236         .suspend = w1_gpio_suspend,
 237         .resume = w1_gpio_resume,
 238 };
 239
 240 module_platform_driver(w1_gpio_driver);
 241
 242 MODULE_DESCRIPTION("GPIO w1 bus master driver");
 243 MODULE_AUTHOR("Ville Syrjala <syrjala@sci.fi>");
 244 MODULE_LICENSE("GPL");