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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * w1-gpio - GPIO w1 bus master driver4 *5 * Copyright (C) 2007 Ville Syrjala <syrjala@sci.fi>6 */7 8#include <linux/delay.h>9#include <linux/device.h>10#include <linux/err.h>11#include <linux/gpio/consumer.h>12#include <linux/mod_devicetable.h>13#include <linux/module.h>14#include <linux/platform_device.h>15#include <linux/property.h>16#include <linux/types.h>17 18#include <linux/w1.h>19 20struct w1_gpio_ddata {21 struct gpio_desc *gpiod;22 struct gpio_desc *pullup_gpiod;23 unsigned int pullup_duration;24};25 26static u8 w1_gpio_set_pullup(void *data, int delay)27{28 struct w1_gpio_ddata *ddata = data;29 30 if (delay) {31 ddata->pullup_duration = delay;32 } else {33 if (ddata->pullup_duration) {34 /*35 * This will OVERRIDE open drain emulation and force-pull36 * the line high for some time.37 */38 gpiod_set_raw_value(ddata->gpiod, 1);39 msleep(ddata->pullup_duration);40 /*41 * This will simply set the line as input since we are doing42 * open drain emulation in the GPIO library.43 */44 gpiod_set_value(ddata->gpiod, 1);45 }46 ddata->pullup_duration = 0;47 }48 49 return 0;50}51 52static void w1_gpio_write_bit(void *data, u8 bit)53{54 struct w1_gpio_ddata *ddata = data;55 56 gpiod_set_value(ddata->gpiod, bit);57}58 59static u8 w1_gpio_read_bit(void *data)60{61 struct w1_gpio_ddata *ddata = data;62 63 return gpiod_get_value(ddata->gpiod) ? 1 : 0;64}65 66static int w1_gpio_probe(struct platform_device *pdev)67{68 struct w1_bus_master *master;69 struct w1_gpio_ddata *ddata;70 struct device *dev = &pdev->dev;71 /* Enforce open drain mode by default */72 enum gpiod_flags gflags = GPIOD_OUT_LOW_OPEN_DRAIN;73 int err;74 75 ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL);76 if (!ddata)77 return -ENOMEM;78 79 /*80 * This parameter means that something else than the gpiolib has81 * already set the line into open drain mode, so we should just82 * driver it high/low like we are in full control of the line and83 * open drain will happen transparently.84 */85 if (device_property_present(dev, "linux,open-drain"))86 gflags = GPIOD_OUT_LOW;87 88 master = devm_kzalloc(dev, sizeof(*master), GFP_KERNEL);89 if (!master)90 return -ENOMEM;91 92 ddata->gpiod = devm_gpiod_get_index(dev, NULL, 0, gflags);93 if (IS_ERR(ddata->gpiod))94 return dev_err_probe(dev, PTR_ERR(ddata->gpiod), "gpio_request (pin) failed\n");95 96 ddata->pullup_gpiod =97 devm_gpiod_get_index_optional(dev, NULL, 1, GPIOD_OUT_LOW);98 if (IS_ERR(ddata->pullup_gpiod))99 return dev_err_probe(dev, PTR_ERR(ddata->pullup_gpiod),100 "gpio_request (ext_pullup_enable_pin) failed\n");101 102 master->data = ddata;103 master->read_bit = w1_gpio_read_bit;104 gpiod_direction_output(ddata->gpiod, 1);105 master->write_bit = w1_gpio_write_bit;106 107 /*108 * If we are using open drain emulation from the GPIO library,109 * we need to use this pullup function that hammers the line110 * high using a raw accessor to provide pull-up for the w1111 * line.112 */113 if (gflags == GPIOD_OUT_LOW_OPEN_DRAIN)114 master->set_pullup = w1_gpio_set_pullup;115 116 err = w1_add_master_device(master);117 if (err)118 return dev_err_probe(dev, err, "w1_add_master device failed\n");119 120 gpiod_set_value(ddata->pullup_gpiod, 1);121 122 platform_set_drvdata(pdev, master);123 124 return 0;125}126 127static void w1_gpio_remove(struct platform_device *pdev)128{129 struct w1_bus_master *master = platform_get_drvdata(pdev);130 struct w1_gpio_ddata *ddata = master->data;131 132 gpiod_set_value(ddata->pullup_gpiod, 0);133 134 w1_remove_master_device(master);135}136 137static const struct of_device_id w1_gpio_dt_ids[] = {138 { .compatible = "w1-gpio" },139 {}140};141MODULE_DEVICE_TABLE(of, w1_gpio_dt_ids);142 143static struct platform_driver w1_gpio_driver = {144 .driver = {145 .name = "w1-gpio",146 .of_match_table = w1_gpio_dt_ids,147 },148 .probe = w1_gpio_probe,149 .remove_new = w1_gpio_remove,150};151 152module_platform_driver(w1_gpio_driver);153 154MODULE_DESCRIPTION("GPIO w1 bus master driver");155MODULE_AUTHOR("Ville Syrjala <syrjala@sci.fi>");156MODULE_LICENSE("GPL");157