// SPDX-License-Identifier: GPL-2.0+
/*
* Raspberry Pi 3 expander GPIO driver
*
* Uses the firmware mailbox service to communicate with the
* GPIO expander on the VPU.
*
* Copyright (C) 2017 Raspberry Pi Trading Ltd.
*/
#include <linux/err.h>
#include <linux/gpio/driver.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <soc/bcm2835/raspberrypi-firmware.h>
#define MODULE_NAME "raspberrypi-exp-gpio"
#define NUM_GPIO 8
#define RPI_EXP_GPIO_BASE 128
#define RPI_EXP_GPIO_DIR_IN 0
#define RPI_EXP_GPIO_DIR_OUT 1
struct rpi_exp_gpio {
struct gpio_chip gc;
struct rpi_firmware *fw;
};
/* VC4 firmware mailbox interface data structures */
struct gpio_set_config {
u32 gpio;
u32 direction;
u32 polarity;
u32 term_en;
u32 term_pull_up;
u32 state;
};
struct gpio_get_config {
u32 gpio;
u32 direction;
u32 polarity;
u32 term_en;
u32 term_pull_up;
};
struct gpio_get_set_state {
u32 gpio;
u32 state;
};
static int rpi_exp_gpio_get_polarity(struct gpio_chip *gc, unsigned int off)
{
struct rpi_exp_gpio *gpio;
struct gpio_get_config get;
int ret;
gpio = gpiochip_get_data(gc);
get.gpio = off + RPI_EXP_GPIO_BASE; /* GPIO to update */
ret = rpi_firmware_property(gpio->fw, RPI_FIRMWARE_GET_GPIO_CONFIG,
&get, sizeof(get));
if (ret || get.gpio != 0) {
dev_err(gc->parent, "Failed to get GPIO %u config (%d %x)\n",
off, ret, get.gpio);
return ret ? ret : -EIO;
}
return get.polarity;
}
static int rpi_exp_gpio_dir_in(struct gpio_chip *gc, unsigned int off)
{
struct rpi_exp_gpio *gpio;
struct gpio_set_config set_in;
int ret;
gpio = gpiochip_get_data(gc);
set_in.gpio = off + RPI_EXP_GPIO_BASE; /* GPIO to update */
set_in.direction = RPI_EXP_GPIO_DIR_IN;
set_in.term_en = 0; /* termination disabled */
set_in.term_pull_up = 0; /* n/a as termination disabled */
set_in.state = 0; /* n/a as configured as an input */
ret = rpi_exp_gpio_get_polarity(gc, off);
if (ret < 0)
return ret;
set_in.polarity = ret; /* Retain existing setting */
ret = rpi_firmware_property(gpio->fw, RPI_FIRMWARE_SET_GPIO_CONFIG,
&set_in, sizeof(set_in));
if (ret || set_in.gpio != 0) {
dev_err(gc->parent, "Failed to set GPIO %u to input (%d %x)\n",
off, ret, set_in.gpio);
return ret ? ret : -EIO;
}
return 0;
}
static int rpi_exp_gpio_dir_out(struct gpio_chip *gc, unsigned int off, int val)
{
struct rpi_exp_gpio *gpio;
struct gpio_set_config set_out;
int ret;
gpio = gpiochip_get_data(gc);
set_out.gpio = off + RPI_EXP_GPIO_BASE; /* GPIO to update */
set_out.direction = RPI_EXP_GPIO_DIR_OUT;
set_out.term_en = 0; /* n/a as an output */
set_out.term_pull_up = 0; /* n/a as termination disabled */
set_out.state = val; /* Output state */
ret = rpi_exp_gpio_get_polarity(gc, off);
if (ret < 0)
return ret;
set_out.polarity = ret; /* Retain existing setting */
ret = rpi_firmware_property(gpio->fw, RPI_FIRMWARE_SET_GPIO_CONFIG,
&set_out, sizeof(set_out));
if (ret || set_out.gpio != 0) {
dev_err(gc->parent, "Failed to set GPIO %u to output (%d %x)\n",
off, ret, set_out.gpio);
return ret ? ret : -EIO;
}
return 0;
}
static int rpi_exp_gpio_get_direction(struct gpio_chip *gc, unsigned int off)
{
struct rpi_exp_gpio *gpio;
struct gpio_get_config get;
int ret;
gpio = gpiochip_get_data(gc);
get.gpio = off + RPI_EXP_GPIO_BASE; /* GPIO to update */
ret = rpi_firmware_property(gpio->fw, RPI_FIRMWARE_GET_GPIO_CONFIG,
&get, sizeof(get));
if (ret || get.gpio != 0) {
dev_err(gc->parent,
"Failed to get GPIO %u config (%d %x)\n", off, ret,
get.gpio);
return ret ? ret : -EIO;
}
return !get.direction;
}
static int rpi_exp_gpio_get(struct gpio_chip *gc, unsigned int off)
{
struct rpi_exp_gpio *gpio;
struct gpio_get_set_state get;
int ret;
gpio = gpiochip_get_data(gc);
get.gpio = off + RPI_EXP_GPIO_BASE; /* GPIO to update */
get.state = 0; /* storage for returned value */
ret = rpi_firmware_property(gpio->fw, RPI_FIRMWARE_GET_GPIO_STATE,
&get, sizeof(get));
if (ret || get.gpio != 0) {
dev_err(gc->parent,
"Failed to get GPIO %u state (%d %x)\n", off, ret,
get.gpio);
return ret ? ret : -EIO;
}
return !!get.state;
}
static void rpi_exp_gpio_set(struct gpio_chip *gc, unsigned int off, int val)
{
struct rpi_exp_gpio *gpio;
struct gpio_get_set_state set;
int ret;
gpio = gpiochip_get_data(gc);
set.gpio = off + RPI_EXP_GPIO_BASE; /* GPIO to update */
set.state = val; /* Output state */
ret = rpi_firmware_property(gpio->fw, RPI_FIRMWARE_SET_GPIO_STATE,
&set, sizeof(set));
if (ret || set.gpio != 0)
dev_err(gc->parent,
"Failed to set GPIO %u state (%d %x)\n", off, ret,
set.gpio);
}
static int rpi_exp_gpio_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct device_node *np = dev->of_node;
struct device_node *fw_node;
struct rpi_firmware *fw;
struct rpi_exp_gpio *rpi_gpio;
fw_node = of_get_parent(np);
if (!fw_node) {
dev_err(dev, "Missing firmware node\n");
return -ENOENT;
}
fw = rpi_firmware_get(fw_node);
of_node_put(fw_node);
if (!fw)
return -EPROBE_DEFER;
rpi_gpio = devm_kzalloc(dev, sizeof(*rpi_gpio), GFP_KERNEL);
if (!rpi_gpio)
return -ENOMEM;
rpi_gpio->fw = fw;
rpi_gpio->gc.parent = dev;
rpi_gpio->gc.label = MODULE_NAME;
rpi_gpio->gc.owner = THIS_MODULE;
rpi_gpio->gc.of_node = np;
rpi_gpio->gc.base = -1;
rpi_gpio->gc.ngpio = NUM_GPIO;
rpi_gpio->gc.direction_input = rpi_exp_gpio_dir_in;
rpi_gpio->gc.direction_output = rpi_exp_gpio_dir_out;
rpi_gpio->gc.get_direction = rpi_exp_gpio_get_direction;
rpi_gpio->gc.get = rpi_exp_gpio_get;
rpi_gpio->gc.set = rpi_exp_gpio_set;
rpi_gpio->gc.can_sleep = true;
return devm_gpiochip_add_data(dev, &rpi_gpio->gc, rpi_gpio);
}
static const struct of_device_id rpi_exp_gpio_ids[] = {
{ .compatible = "raspberrypi,firmware-gpio" },
{ }
};
MODULE_DEVICE_TABLE(of, rpi_exp_gpio_ids);
static struct platform_driver rpi_exp_gpio_driver = {
.driver = {
.name = MODULE_NAME,
.of_match_table = of_match_ptr(rpi_exp_gpio_ids),
},
.probe = rpi_exp_gpio_probe,
};
module_platform_driver(rpi_exp_gpio_driver);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Dave Stevenson <dave.stevenson@raspberrypi.org>");
MODULE_DESCRIPTION("Raspberry Pi 3 expander GPIO driver");
MODULE_ALIAS("platform:rpi-exp-gpio");
