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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(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
47static 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
54static 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)
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(&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
154static 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
170static 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
180static 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
190static SIMPLE_DEV_PM_OPS(w1_gpio_pm_ops, w1_gpio_suspend, w1_gpio_resume);
191
192static 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
202module_platform_driver(w1_gpio_driver);
203
204MODULE_DESCRIPTION("GPIO w1 bus master driver");
205MODULE_AUTHOR("Ville Syrjala <syrjala@sci.fi>");
206MODULE_LICENSE("GPL");
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
22static 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
32static 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
39static 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
46static 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
93static 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
110static 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
120static 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
135static 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
145static int __init w1_gpio_init(void)
146{
147 return platform_driver_probe(&w1_gpio_driver, w1_gpio_probe);
148}
149
150static void __exit w1_gpio_exit(void)
151{
152 platform_driver_unregister(&w1_gpio_driver);
153}
154
155module_init(w1_gpio_init);
156module_exit(w1_gpio_exit);
157
158MODULE_DESCRIPTION("GPIO w1 bus master driver");
159MODULE_AUTHOR("Ville Syrjala <syrjala@sci.fi>");
160MODULE_LICENSE("GPL");