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
21static 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(desc: pdata->gpiod, value: 1);
34 msleep(msecs: 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(desc: pdata->gpiod, value: 1);
40 }
41 pdata->pullup_duration = 0;
42 }
43
44 return 0;
45}
46
47static void w1_gpio_write_bit(void *data, u8 bit)
48{
49 struct w1_gpio_platform_data *pdata = data;
50
51 gpiod_set_value(desc: pdata->gpiod, value: bit);
52}
53
54static u8 w1_gpio_read_bit(void *data)
55{
56 struct w1_gpio_platform_data *pdata = data;
57
58 return gpiod_get_value(desc: pdata->gpiod) ? 1 : 0;
59}
60
61#if defined(CONFIG_OF)
62static const struct of_device_id w1_gpio_dt_ids[] = {
63 { .compatible = "w1-gpio" },
64 {}
65};
66MODULE_DEVICE_TABLE(of, w1_gpio_dt_ids);
67#endif
68
69static 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(dev: &pdev->dev, size: 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_property_present(np, propname: "linux,open-drain"))
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, size: sizeof(struct w1_bus_master),
103 GFP_KERNEL);
104 if (!master)
105 return -ENOMEM;
106
107 pdata->gpiod = devm_gpiod_get_index(dev, NULL, idx: 0, flags: gflags);
108 if (IS_ERR(ptr: pdata->gpiod)) {
109 dev_err(dev, "gpio_request (pin) failed\n");
110 return PTR_ERR(ptr: pdata->gpiod);
111 }
112
113 pdata->pullup_gpiod =
114 devm_gpiod_get_index_optional(dev, NULL, index: 1, flags: GPIOD_OUT_LOW);
115 if (IS_ERR(ptr: pdata->pullup_gpiod)) {
116 dev_err(dev, "gpio_request_one "
117 "(ext_pullup_enable_pin) failed\n");
118 return PTR_ERR(ptr: pdata->pullup_gpiod);
119 }
120
121 master->data = pdata;
122 master->read_bit = w1_gpio_read_bit;
123 gpiod_direction_output(desc: pdata->gpiod, value: 1);
124 master->write_bit = w1_gpio_write_bit;
125
126 /*
127 * If we are using open drain emulation from the GPIO library,
128 * we need to use this pullup function that hammers the line
129 * high using a raw accessor to provide pull-up for the w1
130 * line.
131 */
132 if (gflags == GPIOD_OUT_LOW_OPEN_DRAIN)
133 master->set_pullup = w1_gpio_set_pullup;
134
135 err = w1_add_master_device(master);
136 if (err) {
137 dev_err(dev, "w1_add_master device failed\n");
138 return err;
139 }
140
141 if (pdata->enable_external_pullup)
142 pdata->enable_external_pullup(1);
143
144 if (pdata->pullup_gpiod)
145 gpiod_set_value(desc: pdata->pullup_gpiod, value: 1);
146
147 platform_set_drvdata(pdev, data: master);
148
149 return 0;
150}
151
152static int w1_gpio_remove(struct platform_device *pdev)
153{
154 struct w1_bus_master *master = platform_get_drvdata(pdev);
155 struct w1_gpio_platform_data *pdata = dev_get_platdata(dev: &pdev->dev);
156
157 if (pdata->enable_external_pullup)
158 pdata->enable_external_pullup(0);
159
160 if (pdata->pullup_gpiod)
161 gpiod_set_value(desc: pdata->pullup_gpiod, value: 0);
162
163 w1_remove_master_device(master);
164
165 return 0;
166}
167
168static int __maybe_unused w1_gpio_suspend(struct device *dev)
169{
170 struct w1_gpio_platform_data *pdata = dev_get_platdata(dev);
171
172 if (pdata->enable_external_pullup)
173 pdata->enable_external_pullup(0);
174
175 return 0;
176}
177
178static int __maybe_unused w1_gpio_resume(struct device *dev)
179{
180 struct w1_gpio_platform_data *pdata = dev_get_platdata(dev);
181
182 if (pdata->enable_external_pullup)
183 pdata->enable_external_pullup(1);
184
185 return 0;
186}
187
188static SIMPLE_DEV_PM_OPS(w1_gpio_pm_ops, w1_gpio_suspend, w1_gpio_resume);
189
190static struct platform_driver w1_gpio_driver = {
191 .driver = {
192 .name = "w1-gpio",
193 .pm = &w1_gpio_pm_ops,
194 .of_match_table = of_match_ptr(w1_gpio_dt_ids),
195 },
196 .probe = w1_gpio_probe,
197 .remove = w1_gpio_remove,
198};
199
200module_platform_driver(w1_gpio_driver);
201
202MODULE_DESCRIPTION("GPIO w1 bus master driver");
203MODULE_AUTHOR("Ville Syrjala <syrjala@sci.fi>");
204MODULE_LICENSE("GPL");
205

source code of linux/drivers/w1/masters/w1-gpio.c