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_property_present(np, "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, sizeof(struct w1_bus_master),
103			GFP_KERNEL);
104	if (!master)
105		return -ENOMEM;
106
107	pdata->gpiod = devm_gpiod_get_index(dev, NULL, 0, gflags);
108	if (IS_ERR(pdata->gpiod)) {
109		dev_err(dev, "gpio_request (pin) failed\n");
110		return PTR_ERR(pdata->gpiod);
111	}
112
113	pdata->pullup_gpiod =
114		devm_gpiod_get_index_optional(dev, NULL, 1, GPIOD_OUT_LOW);
115	if (IS_ERR(pdata->pullup_gpiod)) {
116		dev_err(dev, "gpio_request_one "
117			"(ext_pullup_enable_pin) failed\n");
118		return PTR_ERR(pdata->pullup_gpiod);
119	}
120
121	master->data = pdata;
122	master->read_bit = w1_gpio_read_bit;
123	gpiod_direction_output(pdata->gpiod, 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(pdata->pullup_gpiod, 1);
146
147	platform_set_drvdata(pdev, 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(&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(pdata->pullup_gpiod, 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