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
25 struct rpi_exp_gpio {
26 struct gpio_chip gc;
27 struct rpi_firmware *fw;
28 };
29
30 /* VC4 firmware mailbox interface data structures */
31
32 struct 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
41 struct gpio_get_config {
42 u32 gpio;
43 u32 direction;
44 u32 polarity;
45 u32 term_en;
46 u32 term_pull_up;
47 };
48
49 struct gpio_get_set_state {
50 u32 gpio;
51 u32 state;
52 };
53
rpi_exp_gpio_get_polarity(struct gpio_chip * gc,unsigned int off)54 static 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
rpi_exp_gpio_dir_in(struct gpio_chip * gc,unsigned int off)74 static 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
rpi_exp_gpio_dir_out(struct gpio_chip * gc,unsigned int off,int val)103 static 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
rpi_exp_gpio_get_direction(struct gpio_chip * gc,unsigned int off)132 static 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 if (get.direction)
151 return GPIO_LINE_DIRECTION_OUT;
152
153 return GPIO_LINE_DIRECTION_IN;
154 }
155
rpi_exp_gpio_get(struct gpio_chip * gc,unsigned int off)156 static 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(gpio->fw, RPI_FIRMWARE_GET_GPIO_STATE,
168 &get, 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
rpi_exp_gpio_set(struct gpio_chip * gc,unsigned int off,int val)178 static 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(gpio->fw, RPI_FIRMWARE_SET_GPIO_STATE,
190 &set, 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
rpi_exp_gpio_probe(struct platform_device * pdev)197 static 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(np);
206 if (!fw_node) {
207 dev_err(dev, "Missing firmware node\n");
208 return -ENOENT;
209 }
210
211 fw = rpi_firmware_get(fw_node);
212 of_node_put(fw_node);
213 if (!fw)
214 return -EPROBE_DEFER;
215
216 rpi_gpio = devm_kzalloc(dev, 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.of_node = np;
225 rpi_gpio->gc.base = -1;
226 rpi_gpio->gc.ngpio = NUM_GPIO;
227
228 rpi_gpio->gc.direction_input = rpi_exp_gpio_dir_in;
229 rpi_gpio->gc.direction_output = rpi_exp_gpio_dir_out;
230 rpi_gpio->gc.get_direction = rpi_exp_gpio_get_direction;
231 rpi_gpio->gc.get = rpi_exp_gpio_get;
232 rpi_gpio->gc.set = rpi_exp_gpio_set;
233 rpi_gpio->gc.can_sleep = true;
234
235 return devm_gpiochip_add_data(dev, &rpi_gpio->gc, rpi_gpio);
236 }
237
238 static const struct of_device_id rpi_exp_gpio_ids[] = {
239 { .compatible = "raspberrypi,firmware-gpio" },
240 { }
241 };
242 MODULE_DEVICE_TABLE(of, rpi_exp_gpio_ids);
243
244 static struct platform_driver rpi_exp_gpio_driver = {
245 .driver = {
246 .name = MODULE_NAME,
247 .of_match_table = of_match_ptr(rpi_exp_gpio_ids),
248 },
249 .probe = rpi_exp_gpio_probe,
250 };
251 module_platform_driver(rpi_exp_gpio_driver);
252
253 MODULE_LICENSE("GPL");
254 MODULE_AUTHOR("Dave Stevenson <dave.stevenson@raspberrypi.org>");
255 MODULE_DESCRIPTION("Raspberry Pi 3 expander GPIO driver");
256 MODULE_ALIAS("platform:rpi-exp-gpio");
257