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	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(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
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(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
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(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
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