// 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;
        }
        if (get.direction)
                return GPIO_LINE_DIRECTION_OUT;

        return GPIO_LINE_DIRECTION_IN;
}

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 int 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);
                return ret ? ret : -EIO;
        }

        return 0;
}

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 = devm_rpi_firmware_get(&pdev->dev, 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.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 = 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");