1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * Raspberry Pi 3 expander GPIO driver
4 *
5 * Uses the firmware mailbox service to communicate with the
6 * GPIO expander on the VPU.
7 *
8 * Copyright (C) 2017 Raspberry Pi Trading Ltd.
9 */
10
11#include <linux/err.h>
12#include <linux/gpio/driver.h>
13#include <linux/module.h>
14#include <linux/platform_device.h>
15#include <soc/bcm2835/raspberrypi-firmware.h>
16
17#define MODULE_NAME "raspberrypi-exp-gpio"
18#define NUM_GPIO 8
19
20#define RPI_EXP_GPIO_BASE 128
21
22#define RPI_EXP_GPIO_DIR_IN 0
23#define RPI_EXP_GPIO_DIR_OUT 1
24
25struct rpi_exp_gpio {
26 struct gpio_chip gc;
27 struct rpi_firmware *fw;
28};
29
30/* VC4 firmware mailbox interface data structures */
31
32struct gpio_set_config {
33 u32 gpio;
34 u32 direction;
35 u32 polarity;
36 u32 term_en;
37 u32 term_pull_up;
38 u32 state;
39};
40
41struct gpio_get_config {
42 u32 gpio;
43 u32 direction;
44 u32 polarity;
45 u32 term_en;
46 u32 term_pull_up;
47};
48
49struct gpio_get_set_state {
50 u32 gpio;
51 u32 state;
52};
53
54static int rpi_exp_gpio_get_polarity(struct gpio_chip *gc, unsigned int off)
55{
56 struct rpi_exp_gpio *gpio;
57 struct gpio_get_config get;
58 int ret;
59
60 gpio = gpiochip_get_data(gc);
61
62 get.gpio = off + RPI_EXP_GPIO_BASE; /* GPIO to update */
63
64 ret = rpi_firmware_property(fw: gpio->fw, tag: RPI_FIRMWARE_GET_GPIO_CONFIG,
65 data: &get, len: sizeof(get));
66 if (ret || get.gpio != 0) {
67 dev_err(gc->parent, "Failed to get GPIO %u config (%d %x)\n",
68 off, ret, get.gpio);
69 return ret ? ret : -EIO;
70 }
71 return get.polarity;
72}
73
74static int rpi_exp_gpio_dir_in(struct gpio_chip *gc, unsigned int off)
75{
76 struct rpi_exp_gpio *gpio;
77 struct gpio_set_config set_in;
78 int ret;
79
80 gpio = gpiochip_get_data(gc);
81
82 set_in.gpio = off + RPI_EXP_GPIO_BASE; /* GPIO to update */
83 set_in.direction = RPI_EXP_GPIO_DIR_IN;
84 set_in.term_en = 0; /* termination disabled */
85 set_in.term_pull_up = 0; /* n/a as termination disabled */
86 set_in.state = 0; /* n/a as configured as an input */
87
88 ret = rpi_exp_gpio_get_polarity(gc, off);
89 if (ret < 0)
90 return ret;
91 set_in.polarity = ret; /* Retain existing setting */
92
93 ret = rpi_firmware_property(fw: gpio->fw, tag: RPI_FIRMWARE_SET_GPIO_CONFIG,
94 data: &set_in, len: sizeof(set_in));
95 if (ret || set_in.gpio != 0) {
96 dev_err(gc->parent, "Failed to set GPIO %u to input (%d %x)\n",
97 off, ret, set_in.gpio);
98 return ret ? ret : -EIO;
99 }
100 return 0;
101}
102
103static int rpi_exp_gpio_dir_out(struct gpio_chip *gc, unsigned int off, int val)
104{
105 struct rpi_exp_gpio *gpio;
106 struct gpio_set_config set_out;
107 int ret;
108
109 gpio = gpiochip_get_data(gc);
110
111 set_out.gpio = off + RPI_EXP_GPIO_BASE; /* GPIO to update */
112 set_out.direction = RPI_EXP_GPIO_DIR_OUT;
113 set_out.term_en = 0; /* n/a as an output */
114 set_out.term_pull_up = 0; /* n/a as termination disabled */
115 set_out.state = val; /* Output state */
116
117 ret = rpi_exp_gpio_get_polarity(gc, off);
118 if (ret < 0)
119 return ret;
120 set_out.polarity = ret; /* Retain existing setting */
121
122 ret = rpi_firmware_property(fw: gpio->fw, tag: RPI_FIRMWARE_SET_GPIO_CONFIG,
123 data: &set_out, len: sizeof(set_out));
124 if (ret || set_out.gpio != 0) {
125 dev_err(gc->parent, "Failed to set GPIO %u to output (%d %x)\n",
126 off, ret, set_out.gpio);
127 return ret ? ret : -EIO;
128 }
129 return 0;
130}
131
132static int rpi_exp_gpio_get_direction(struct gpio_chip *gc, unsigned int off)
133{
134 struct rpi_exp_gpio *gpio;
135 struct gpio_get_config get;
136 int ret;
137
138 gpio = gpiochip_get_data(gc);
139
140 get.gpio = off + RPI_EXP_GPIO_BASE; /* GPIO to update */
141
142 ret = rpi_firmware_property(fw: gpio->fw, tag: RPI_FIRMWARE_GET_GPIO_CONFIG,
143 data: &get, len: sizeof(get));
144 if (ret || get.gpio != 0) {
145 dev_err(gc->parent,
146 "Failed to get GPIO %u config (%d %x)\n", off, ret,
147 get.gpio);
148 return ret ? ret : -EIO;
149 }
150 if (get.direction)
151 return GPIO_LINE_DIRECTION_OUT;
152
153 return GPIO_LINE_DIRECTION_IN;
154}
155
156static int rpi_exp_gpio_get(struct gpio_chip *gc, unsigned int off)
157{
158 struct rpi_exp_gpio *gpio;
159 struct gpio_get_set_state get;
160 int ret;
161
162 gpio = gpiochip_get_data(gc);
163
164 get.gpio = off + RPI_EXP_GPIO_BASE; /* GPIO to update */
165 get.state = 0; /* storage for returned value */
166
167 ret = rpi_firmware_property(fw: gpio->fw, tag: RPI_FIRMWARE_GET_GPIO_STATE,
168 data: &get, len: sizeof(get));
169 if (ret || get.gpio != 0) {
170 dev_err(gc->parent,
171 "Failed to get GPIO %u state (%d %x)\n", off, ret,
172 get.gpio);
173 return ret ? ret : -EIO;
174 }
175 return !!get.state;
176}
177
178static void rpi_exp_gpio_set(struct gpio_chip *gc, unsigned int off, int val)
179{
180 struct rpi_exp_gpio *gpio;
181 struct gpio_get_set_state set;
182 int ret;
183
184 gpio = gpiochip_get_data(gc);
185
186 set.gpio = off + RPI_EXP_GPIO_BASE; /* GPIO to update */
187 set.state = val; /* Output state */
188
189 ret = rpi_firmware_property(fw: gpio->fw, tag: RPI_FIRMWARE_SET_GPIO_STATE,
190 data: &set, len: sizeof(set));
191 if (ret || set.gpio != 0)
192 dev_err(gc->parent,
193 "Failed to set GPIO %u state (%d %x)\n", off, ret,
194 set.gpio);
195}
196
197static int rpi_exp_gpio_probe(struct platform_device *pdev)
198{
199 struct device *dev = &pdev->dev;
200 struct device_node *np = dev->of_node;
201 struct device_node *fw_node;
202 struct rpi_firmware *fw;
203 struct rpi_exp_gpio *rpi_gpio;
204
205 fw_node = of_get_parent(node: np);
206 if (!fw_node) {
207 dev_err(dev, "Missing firmware node\n");
208 return -ENOENT;
209 }
210
211 fw = devm_rpi_firmware_get(dev: &pdev->dev, firmware_node: fw_node);
212 of_node_put(node: fw_node);
213 if (!fw)
214 return -EPROBE_DEFER;
215
216 rpi_gpio = devm_kzalloc(dev, size: sizeof(*rpi_gpio), GFP_KERNEL);
217 if (!rpi_gpio)
218 return -ENOMEM;
219
220 rpi_gpio->fw = fw;
221 rpi_gpio->gc.parent = dev;
222 rpi_gpio->gc.label = MODULE_NAME;
223 rpi_gpio->gc.owner = THIS_MODULE;
224 rpi_gpio->gc.base = -1;
225 rpi_gpio->gc.ngpio = NUM_GPIO;
226
227 rpi_gpio->gc.direction_input = rpi_exp_gpio_dir_in;
228 rpi_gpio->gc.direction_output = rpi_exp_gpio_dir_out;
229 rpi_gpio->gc.get_direction = rpi_exp_gpio_get_direction;
230 rpi_gpio->gc.get = rpi_exp_gpio_get;
231 rpi_gpio->gc.set = rpi_exp_gpio_set;
232 rpi_gpio->gc.can_sleep = true;
233
234 return devm_gpiochip_add_data(dev, &rpi_gpio->gc, rpi_gpio);
235}
236
237static const struct of_device_id rpi_exp_gpio_ids[] = {
238 { .compatible = "raspberrypi,firmware-gpio" },
239 { }
240};
241MODULE_DEVICE_TABLE(of, rpi_exp_gpio_ids);
242
243static struct platform_driver rpi_exp_gpio_driver = {
244 .driver = {
245 .name = MODULE_NAME,
246 .of_match_table = rpi_exp_gpio_ids,
247 },
248 .probe = rpi_exp_gpio_probe,
249};
250module_platform_driver(rpi_exp_gpio_driver);
251
252MODULE_LICENSE("GPL");
253MODULE_AUTHOR("Dave Stevenson <dave.stevenson@raspberrypi.org>");
254MODULE_DESCRIPTION("Raspberry Pi 3 expander GPIO driver");
255MODULE_ALIAS("platform:rpi-exp-gpio");
256

source code of linux/drivers/gpio/gpio-raspberrypi-exp.c