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 = devm_rpi_firmware_get(&pdev->dev, 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.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 
237 static const struct of_device_id rpi_exp_gpio_ids[] = {
238 	{ .compatible = "raspberrypi,firmware-gpio" },
239 	{ }
240 };
241 MODULE_DEVICE_TABLE(of, rpi_exp_gpio_ids);
242 
243 static 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 };
250 module_platform_driver(rpi_exp_gpio_driver);
251 
252 MODULE_LICENSE("GPL");
253 MODULE_AUTHOR("Dave Stevenson <dave.stevenson@raspberrypi.org>");
254 MODULE_DESCRIPTION("Raspberry Pi 3 expander GPIO driver");
255 MODULE_ALIAS("platform:rpi-exp-gpio");
256