drivers/w1/masters/w1-gpio.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * w1-gpio - GPIO w1 bus master driver
   4  *
   5  * Copyright (C) 2007 Ville Syrjala <syrjala@sci.fi>
   6  */
   7
   8 #include <linux/init.h>
   9 #include <linux/module.h>
  10 #include <linux/platform_device.h>
  11 #include <linux/slab.h>
  12 #include <linux/w1-gpio.h>
  13 #include <linux/gpio/consumer.h>
  14 #include <linux/of_platform.h>
  15 #include <linux/err.h>
  16 #include <linux/of.h>
  17 #include <linux/delay.h>
  18
  19 #include <linux/w1.h>
  20
  21 static u8 w1_gpio_set_pullup(void *data, int delay)
  22 {
  23         struct w1_gpio_platform_data *pdata = data;
  24
  25         if (delay) {
  26                 pdata->pullup_duration = delay;
  27         } else {
  28                 if (pdata->pullup_duration) {
  29                         /*
  30                          * This will OVERRIDE open drain emulation and force-pull
  31                          * the line high for some time.
  32                          */
  33                         gpiod_set_raw_value(pdata->gpiod, 1);
  34                         msleep(pdata->pullup_duration);
  35                         /*
  36                          * This will simply set the line as input since we are doing
  37                          * open drain emulation in the GPIO library.
  38                          */
  39                         gpiod_set_value(pdata->gpiod, 1);
  40                 }
  41                 pdata->pullup_duration = 0;
  42         }
  43
  44         return 0;
  45 }
  46
  47 static void w1_gpio_write_bit(void *data, u8 bit)
  48 {
  49         struct w1_gpio_platform_data *pdata = data;
  50
  51         gpiod_set_value(pdata->gpiod, bit);
  52 }
  53
  54 static u8 w1_gpio_read_bit(void *data)
  55 {
  56         struct w1_gpio_platform_data *pdata = data;
  57
  58         return gpiod_get_value(pdata->gpiod) ? 1 : 0;
  59 }
  60
  61 #if defined(CONFIG_OF)
  62 static const struct of_device_id w1_gpio_dt_ids[] = {
  63         { .compatible = "w1-gpio" },
  64         {}
  65 };
  66 MODULE_DEVICE_TABLE(of, w1_gpio_dt_ids);
  67 #endif
  68
  69 static int w1_gpio_probe(struct platform_device *pdev)
  70 {
  71         struct w1_bus_master *master;
  72         struct w1_gpio_platform_data *pdata;
  73         struct device *dev = &pdev->dev;
  74         struct device_node *np = dev->of_node;
  75         /* Enforce open drain mode by default */
  76         enum gpiod_flags gflags = GPIOD_OUT_LOW_OPEN_DRAIN;
  77         int err;
  78
  79         if (of_have_populated_dt()) {
  80                 pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
  81                 if (!pdata)
  82                         return -ENOMEM;
  83
  84                 /*
  85                  * This parameter means that something else than the gpiolib has
  86                  * already set the line into open drain mode, so we should just
  87                  * driver it high/low like we are in full control of the line and
  88                  * open drain will happen transparently.
  89                  */
  90                 if (of_get_property(np, "linux,open-drain", NULL))
  91                         gflags = GPIOD_OUT_LOW;
  92
  93                 pdev->dev.platform_data = pdata;
  94         }
  95         pdata = dev_get_platdata(dev);
  96
  97         if (!pdata) {
  98                 dev_err(dev, "No configuration data\n");
  99                 return -ENXIO;
 100         }
 101
 102         master = devm_kzalloc(dev, sizeof(struct w1_bus_master),
 103                         GFP_KERNEL);
 104         if (!master) {
 105                 dev_err(dev, "Out of memory\n");
 106                 return -ENOMEM;
 107         }
 108
 109         pdata->gpiod = devm_gpiod_get_index(dev, NULL, 0, gflags);
 110         if (IS_ERR(pdata->gpiod)) {
 111                 dev_err(dev, "gpio_request (pin) failed\n");
 112                 return PTR_ERR(pdata->gpiod);
 113         }
 114
 115         pdata->pullup_gpiod =
 116                 devm_gpiod_get_index_optional(dev, NULL, 1, GPIOD_OUT_LOW);
 117         if (IS_ERR(pdata->pullup_gpiod)) {
 118                 dev_err(dev, "gpio_request_one "
 119                         "(ext_pullup_enable_pin) failed\n");
 120                 return PTR_ERR(pdata->pullup_gpiod);
 121         }
 122
 123         master->data = pdata;
 124         master->read_bit = w1_gpio_read_bit;
 125         gpiod_direction_output(pdata->gpiod, 1);
 126         master->write_bit = w1_gpio_write_bit;
 127
 128         /*
 129          * If we are using open drain emulation from the GPIO library,
 130          * we need to use this pullup function that hammers the line
 131          * high using a raw accessor to provide pull-up for the w1
 132          * line.
 133          */
 134         if (gflags == GPIOD_OUT_LOW_OPEN_DRAIN)
 135                 master->set_pullup = w1_gpio_set_pullup;
 136
 137         err = w1_add_master_device(master);
 138         if (err) {
 139                 dev_err(dev, "w1_add_master device failed\n");
 140                 return err;
 141         }
 142
 143         if (pdata->enable_external_pullup)
 144                 pdata->enable_external_pullup(1);
 145
 146         if (pdata->pullup_gpiod)
 147                 gpiod_set_value(pdata->pullup_gpiod, 1);
 148
 149         platform_set_drvdata(pdev, master);
 150
 151         return 0;
 152 }
 153
 154 static int w1_gpio_remove(struct platform_device *pdev)
 155 {
 156         struct w1_bus_master *master = platform_get_drvdata(pdev);
 157         struct w1_gpio_platform_data *pdata = dev_get_platdata(&pdev->dev);
 158
 159         if (pdata->enable_external_pullup)
 160                 pdata->enable_external_pullup(0);
 161
 162         if (pdata->pullup_gpiod)
 163                 gpiod_set_value(pdata->pullup_gpiod, 0);
 164
 165         w1_remove_master_device(master);
 166
 167         return 0;
 168 }
 169
 170 static int __maybe_unused w1_gpio_suspend(struct device *dev)
 171 {
 172         struct w1_gpio_platform_data *pdata = dev_get_platdata(dev);
 173
 174         if (pdata->enable_external_pullup)
 175                 pdata->enable_external_pullup(0);
 176
 177         return 0;
 178 }
 179
 180 static int __maybe_unused w1_gpio_resume(struct device *dev)
 181 {
 182         struct w1_gpio_platform_data *pdata = dev_get_platdata(dev);
 183
 184         if (pdata->enable_external_pullup)
 185                 pdata->enable_external_pullup(1);
 186
 187         return 0;
 188 }
 189
 190 static SIMPLE_DEV_PM_OPS(w1_gpio_pm_ops, w1_gpio_suspend, w1_gpio_resume);
 191
 192 static struct platform_driver w1_gpio_driver = {
 193         .driver = {
 194                 .name   = "w1-gpio",
 195                 .pm     = &w1_gpio_pm_ops,
 196                 .of_match_table = of_match_ptr(w1_gpio_dt_ids),
 197         },
 198         .probe = w1_gpio_probe,
 199         .remove = w1_gpio_remove,
 200 };
 201
 202 module_platform_driver(w1_gpio_driver);
 203
 204 MODULE_DESCRIPTION("GPIO w1 bus master driver");
 205 MODULE_AUTHOR("Ville Syrjala <syrjala@sci.fi>");
 206 MODULE_LICENSE("GPL");