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(gpio->fw, RPI_FIRMWARE_GET_GPIO_CONFIG,
65 &get, 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(gpio->fw, RPI_FIRMWARE_SET_GPIO_CONFIG,
94 &set_in, 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(gpio->fw, RPI_FIRMWARE_SET_GPIO_CONFIG,
123 &set_out, 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(gpio->fw, RPI_FIRMWARE_GET_GPIO_CONFIG,
143 &get, 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 return !get.direction;
151}
152
153static int rpi_exp_gpio_get(struct gpio_chip *gc, unsigned int off)
154{
155 struct rpi_exp_gpio *gpio;
156 struct gpio_get_set_state get;
157 int ret;
158
159 gpio = gpiochip_get_data(gc);
160
161 get.gpio = off + RPI_EXP_GPIO_BASE; /* GPIO to update */
162 get.state = 0; /* storage for returned value */
163
164 ret = rpi_firmware_property(gpio->fw, RPI_FIRMWARE_GET_GPIO_STATE,
165 &get, sizeof(get));
166 if (ret || get.gpio != 0) {
167 dev_err(gc->parent,
168 "Failed to get GPIO %u state (%d %x)\n", off, ret,
169 get.gpio);
170 return ret ? ret : -EIO;
171 }
172 return !!get.state;
173}
174
175static void rpi_exp_gpio_set(struct gpio_chip *gc, unsigned int off, int val)
176{
177 struct rpi_exp_gpio *gpio;
178 struct gpio_get_set_state set;
179 int ret;
180
181 gpio = gpiochip_get_data(gc);
182
183 set.gpio = off + RPI_EXP_GPIO_BASE; /* GPIO to update */
184 set.state = val; /* Output state */
185
186 ret = rpi_firmware_property(gpio->fw, RPI_FIRMWARE_SET_GPIO_STATE,
187 &set, sizeof(set));
188 if (ret || set.gpio != 0)
189 dev_err(gc->parent,
190 "Failed to set GPIO %u state (%d %x)\n", off, ret,
191 set.gpio);
192}
193
194static int rpi_exp_gpio_probe(struct platform_device *pdev)
195{
196 struct device *dev = &pdev->dev;
197 struct device_node *np = dev->of_node;
198 struct device_node *fw_node;
199 struct rpi_firmware *fw;
200 struct rpi_exp_gpio *rpi_gpio;
201
202 fw_node = of_get_parent(np);
203 if (!fw_node) {
204 dev_err(dev, "Missing firmware node\n");
205 return -ENOENT;
206 }
207
208 fw = rpi_firmware_get(fw_node);
209 of_node_put(fw_node);
210 if (!fw)
211 return -EPROBE_DEFER;
212
213 rpi_gpio = devm_kzalloc(dev, sizeof(*rpi_gpio), GFP_KERNEL);
214 if (!rpi_gpio)
215 return -ENOMEM;
216
217 rpi_gpio->fw = fw;
218 rpi_gpio->gc.parent = dev;
219 rpi_gpio->gc.label = MODULE_NAME;
220 rpi_gpio->gc.owner = THIS_MODULE;
221 rpi_gpio->gc.of_node = np;
222 rpi_gpio->gc.base = -1;
223 rpi_gpio->gc.ngpio = NUM_GPIO;
224
225 rpi_gpio->gc.direction_input = rpi_exp_gpio_dir_in;
226 rpi_gpio->gc.direction_output = rpi_exp_gpio_dir_out;
227 rpi_gpio->gc.get_direction = rpi_exp_gpio_get_direction;
228 rpi_gpio->gc.get = rpi_exp_gpio_get;
229 rpi_gpio->gc.set = rpi_exp_gpio_set;
230 rpi_gpio->gc.can_sleep = true;
231
232 return devm_gpiochip_add_data(dev, &rpi_gpio->gc, rpi_gpio);
233}
234
235static const struct of_device_id rpi_exp_gpio_ids[] = {
236 { .compatible = "raspberrypi,firmware-gpio" },
237 { }
238};
239MODULE_DEVICE_TABLE(of, rpi_exp_gpio_ids);
240
241static struct platform_driver rpi_exp_gpio_driver = {
242 .driver = {
243 .name = MODULE_NAME,
244 .of_match_table = of_match_ptr(rpi_exp_gpio_ids),
245 },
246 .probe = rpi_exp_gpio_probe,
247};
248module_platform_driver(rpi_exp_gpio_driver);
249
250MODULE_LICENSE("GPL");
251MODULE_AUTHOR("Dave Stevenson <dave.stevenson@raspberrypi.org>");
252MODULE_DESCRIPTION("Raspberry Pi 3 expander GPIO driver");
253MODULE_ALIAS("platform:rpi-exp-gpio");
254