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 | #include <linux/gpio/consumer.h> |
17 | #include <linux/of_platform.h> |
18 | #include <linux/err.h> |
19 | #include <linux/of.h> |
20 | #include <linux/delay.h> |
21 | |
22 | #include <linux/w1.h> |
23 | |
24 | static u8 w1_gpio_set_pullup(void *data, int delay) |
25 | { |
26 | struct w1_gpio_platform_data *pdata = data; |
27 | |
28 | if (delay) { |
29 | pdata->pullup_duration = delay; |
30 | } else { |
31 | if (pdata->pullup_duration) { |
32 | /* |
33 | * This will OVERRIDE open drain emulation and force-pull |
34 | * the line high for some time. |
35 | */ |
36 | gpiod_set_raw_value(pdata->gpiod, 1); |
37 | msleep(pdata->pullup_duration); |
38 | /* |
39 | * This will simply set the line as input since we are doing |
40 | * open drain emulation in the GPIO library. |
41 | */ |
42 | gpiod_set_value(pdata->gpiod, 1); |
43 | } |
44 | pdata->pullup_duration = 0; |
45 | } |
46 | |
47 | return 0; |
48 | } |
49 | |
50 | static void w1_gpio_write_bit(void *data, u8 bit) |
51 | { |
52 | struct w1_gpio_platform_data *pdata = data; |
53 | |
54 | gpiod_set_value(pdata->gpiod, bit); |
55 | } |
56 | |
57 | static u8 w1_gpio_read_bit(void *data) |
58 | { |
59 | struct w1_gpio_platform_data *pdata = data; |
60 | |
61 | return gpiod_get_value(pdata->gpiod) ? 1 : 0; |
62 | } |
63 | |
64 | #if defined(CONFIG_OF) |
65 | static const struct of_device_id w1_gpio_dt_ids[] = { |
66 | { .compatible = "w1-gpio" }, |
67 | {} |
68 | }; |
69 | MODULE_DEVICE_TABLE(of, w1_gpio_dt_ids); |
70 | #endif |
71 | |
72 | static int w1_gpio_probe(struct platform_device *pdev) |
73 | { |
74 | struct w1_bus_master *master; |
75 | struct w1_gpio_platform_data *pdata; |
76 | struct device *dev = &pdev->dev; |
77 | struct device_node *np = dev->of_node; |
78 | /* Enforce open drain mode by default */ |
79 | enum gpiod_flags gflags = GPIOD_OUT_LOW_OPEN_DRAIN; |
80 | int err; |
81 | |
82 | if (of_have_populated_dt()) { |
83 | pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL); |
84 | if (!pdata) |
85 | return -ENOMEM; |
86 | |
87 | /* |
88 | * This parameter means that something else than the gpiolib has |
89 | * already set the line into open drain mode, so we should just |
90 | * driver it high/low like we are in full control of the line and |
91 | * open drain will happen transparently. |
92 | */ |
93 | if (of_get_property(np, "linux,open-drain" , NULL)) |
94 | gflags = GPIOD_OUT_LOW; |
95 | |
96 | pdev->dev.platform_data = pdata; |
97 | } |
98 | pdata = dev_get_platdata(dev); |
99 | |
100 | if (!pdata) { |
101 | dev_err(dev, "No configuration data\n" ); |
102 | return -ENXIO; |
103 | } |
104 | |
105 | master = devm_kzalloc(dev, sizeof(struct w1_bus_master), |
106 | GFP_KERNEL); |
107 | if (!master) { |
108 | dev_err(dev, "Out of memory\n" ); |
109 | return -ENOMEM; |
110 | } |
111 | |
112 | pdata->gpiod = devm_gpiod_get_index(dev, NULL, 0, gflags); |
113 | if (IS_ERR(pdata->gpiod)) { |
114 | dev_err(dev, "gpio_request (pin) failed\n" ); |
115 | return PTR_ERR(pdata->gpiod); |
116 | } |
117 | |
118 | pdata->pullup_gpiod = |
119 | devm_gpiod_get_index_optional(dev, NULL, 1, GPIOD_OUT_LOW); |
120 | if (IS_ERR(pdata->pullup_gpiod)) { |
121 | dev_err(dev, "gpio_request_one " |
122 | "(ext_pullup_enable_pin) failed\n" ); |
123 | return PTR_ERR(pdata->pullup_gpiod); |
124 | } |
125 | |
126 | master->data = pdata; |
127 | master->read_bit = w1_gpio_read_bit; |
128 | gpiod_direction_output(pdata->gpiod, 1); |
129 | master->write_bit = w1_gpio_write_bit; |
130 | |
131 | /* |
132 | * If we are using open drain emulation from the GPIO library, |
133 | * we need to use this pullup function that hammers the line |
134 | * high using a raw accessor to provide pull-up for the w1 |
135 | * line. |
136 | */ |
137 | if (gflags == GPIOD_OUT_LOW_OPEN_DRAIN) |
138 | master->set_pullup = w1_gpio_set_pullup; |
139 | |
140 | err = w1_add_master_device(master); |
141 | if (err) { |
142 | dev_err(dev, "w1_add_master device failed\n" ); |
143 | return err; |
144 | } |
145 | |
146 | if (pdata->enable_external_pullup) |
147 | pdata->enable_external_pullup(1); |
148 | |
149 | if (pdata->pullup_gpiod) |
150 | gpiod_set_value(pdata->pullup_gpiod, 1); |
151 | |
152 | platform_set_drvdata(pdev, master); |
153 | |
154 | return 0; |
155 | } |
156 | |
157 | static int w1_gpio_remove(struct platform_device *pdev) |
158 | { |
159 | struct w1_bus_master *master = platform_get_drvdata(pdev); |
160 | struct w1_gpio_platform_data *pdata = dev_get_platdata(&pdev->dev); |
161 | |
162 | if (pdata->enable_external_pullup) |
163 | pdata->enable_external_pullup(0); |
164 | |
165 | if (pdata->pullup_gpiod) |
166 | gpiod_set_value(pdata->pullup_gpiod, 0); |
167 | |
168 | w1_remove_master_device(master); |
169 | |
170 | return 0; |
171 | } |
172 | |
173 | static int __maybe_unused w1_gpio_suspend(struct device *dev) |
174 | { |
175 | struct w1_gpio_platform_data *pdata = dev_get_platdata(dev); |
176 | |
177 | if (pdata->enable_external_pullup) |
178 | pdata->enable_external_pullup(0); |
179 | |
180 | return 0; |
181 | } |
182 | |
183 | static int __maybe_unused w1_gpio_resume(struct device *dev) |
184 | { |
185 | struct w1_gpio_platform_data *pdata = dev_get_platdata(dev); |
186 | |
187 | if (pdata->enable_external_pullup) |
188 | pdata->enable_external_pullup(1); |
189 | |
190 | return 0; |
191 | } |
192 | |
193 | static SIMPLE_DEV_PM_OPS(w1_gpio_pm_ops, w1_gpio_suspend, w1_gpio_resume); |
194 | |
195 | static struct platform_driver w1_gpio_driver = { |
196 | .driver = { |
197 | .name = "w1-gpio" , |
198 | .pm = &w1_gpio_pm_ops, |
199 | .of_match_table = of_match_ptr(w1_gpio_dt_ids), |
200 | }, |
201 | .probe = w1_gpio_probe, |
202 | .remove = w1_gpio_remove, |
203 | }; |
204 | |
205 | module_platform_driver(w1_gpio_driver); |
206 | |
207 | MODULE_DESCRIPTION("GPIO w1 bus master driver" ); |
208 | MODULE_AUTHOR("Ville Syrjala <syrjala@sci.fi>" ); |
209 | MODULE_LICENSE("GPL" ); |
210 | |