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 = 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
238static const struct of_device_id rpi_exp_gpio_ids[] = {
239	{ .compatible = "raspberrypi,firmware-gpio" },
240	{ }
241};
242MODULE_DEVICE_TABLE(of, rpi_exp_gpio_ids);
243
244static 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};
251module_platform_driver(rpi_exp_gpio_driver);
252
253MODULE_LICENSE("GPL");
254MODULE_AUTHOR("Dave Stevenson <dave.stevenson@raspberrypi.org>");
255MODULE_DESCRIPTION("Raspberry Pi 3 expander GPIO driver");
256MODULE_ALIAS("platform:rpi-exp-gpio");