// SPDX-License-Identifier: GPL-2.0
/*
 * GPIO Greybus driver.
 *
 * Copyright 2014 Google Inc.
 * Copyright 2014 Linaro Ltd.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/irq.h>
#include <linux/irqdomain.h>
#include <linux/gpio/driver.h>
#include <linux/mutex.h>
#include <linux/greybus.h>

#include "gbphy.h"

struct gb_gpio_line {
        /* The following has to be an array of line_max entries */
        /* --> make them just a flags field */
        u8                      active:    1,
                                direction: 1,   /* 0 = output, 1 = input */
                                value:     1;   /* 0 = low, 1 = high */
        u16                     debounce_usec;

        u8                      irq_type;
        bool                    irq_type_pending;
        bool                    masked;
        bool                    masked_pending;
};

struct gb_gpio_controller {
        struct gbphy_device     *gbphy_dev;
        struct gb_connection    *connection;
        u8                      line_max;       /* max line number */
        struct gb_gpio_line     *lines;

        struct gpio_chip        chip;
        struct irq_chip         irqc;
        struct mutex            irq_lock;
};

static struct gpio_chip *irq_data_to_gpio_chip(struct irq_data *d)
{
        return d->domain->host_data;
}

static int gb_gpio_line_count_operation(struct gb_gpio_controller *ggc)
{
        struct gb_gpio_line_count_response response;
        int ret;

        ret = gb_operation_sync(ggc->connection, GB_GPIO_TYPE_LINE_COUNT,
                                NULL, 0, &response, sizeof(response));
        if (!ret)
                ggc->line_max = response.count;
        return ret;
}

static int gb_gpio_activate_operation(struct gb_gpio_controller *ggc, u8 which)
{
        struct gb_gpio_activate_request request;
        struct gbphy_device *gbphy_dev = ggc->gbphy_dev;
        int ret;

        ret = gbphy_runtime_get_sync(gbphy_dev);
        if (ret)
                return ret;

        request.which = which;
        ret = gb_operation_sync(ggc->connection, GB_GPIO_TYPE_ACTIVATE,
                                &request, sizeof(request), NULL, 0);
        if (ret) {
                gbphy_runtime_put_autosuspend(gbphy_dev);
                return ret;
        }

        ggc->lines[which].active = true;

        return 0;
}

static void gb_gpio_deactivate_operation(struct gb_gpio_controller *ggc,
                                         u8 which)
{
        struct gbphy_device *gbphy_dev = ggc->gbphy_dev;
        struct device *dev = &gbphy_dev->dev;
        struct gb_gpio_deactivate_request request;
        int ret;

        request.which = which;
        ret = gb_operation_sync(ggc->connection, GB_GPIO_TYPE_DEACTIVATE,
                                &request, sizeof(request), NULL, 0);
        if (ret) {
                dev_err(dev, "failed to deactivate gpio %u\n", which);
                goto out_pm_put;
        }

        ggc->lines[which].active = false;

out_pm_put:
        gbphy_runtime_put_autosuspend(gbphy_dev);
}

static int gb_gpio_get_direction_operation(struct gb_gpio_controller *ggc,
                                           u8 which)
{
        struct device *dev = &ggc->gbphy_dev->dev;
        struct gb_gpio_get_direction_request request;
        struct gb_gpio_get_direction_response response;
        int ret;
        u8 direction;

        request.which = which;
        ret = gb_operation_sync(ggc->connection, GB_GPIO_TYPE_GET_DIRECTION,
                                &request, sizeof(request),
                                &response, sizeof(response));
        if (ret)
                return ret;

        direction = response.direction;
        if (direction && direction != 1) {
                dev_warn(dev, "gpio %u direction was %u (should be 0 or 1)\n",
                         which, direction);
        }
        ggc->lines[which].direction = direction ? 1 : 0;
        return 0;
}

static int gb_gpio_direction_in_operation(struct gb_gpio_controller *ggc,
                                          u8 which)
{
        struct gb_gpio_direction_in_request request;
        int ret;

        request.which = which;
        ret = gb_operation_sync(ggc->connection, GB_GPIO_TYPE_DIRECTION_IN,
                                &request, sizeof(request), NULL, 0);
        if (!ret)
                ggc->lines[which].direction = 1;
        return ret;
}

static int gb_gpio_direction_out_operation(struct gb_gpio_controller *ggc,
                                           u8 which, bool value_high)
{
        struct gb_gpio_direction_out_request request;
        int ret;

        request.which = which;
        request.value = value_high ? 1 : 0;
        ret = gb_operation_sync(ggc->connection, GB_GPIO_TYPE_DIRECTION_OUT,
                                &request, sizeof(request), NULL, 0);
        if (!ret)
                ggc->lines[which].direction = 0;
        return ret;
}

static int gb_gpio_get_value_operation(struct gb_gpio_controller *ggc,
                                       u8 which)
{
        struct device *dev = &ggc->gbphy_dev->dev;
        struct gb_gpio_get_value_request request;
        struct gb_gpio_get_value_response response;
        int ret;
        u8 value;

        request.which = which;
        ret = gb_operation_sync(ggc->connection, GB_GPIO_TYPE_GET_VALUE,
                                &request, sizeof(request),
                                &response, sizeof(response));
        if (ret) {
                dev_err(dev, "failed to get value of gpio %u\n", which);
                return ret;
        }

        value = response.value;
        if (value && value != 1) {
                dev_warn(dev, "gpio %u value was %u (should be 0 or 1)\n",
                         which, value);
        }
        ggc->lines[which].value = value ? 1 : 0;
        return 0;
}

static int gb_gpio_set_value_operation(struct gb_gpio_controller *ggc,
                                       u8 which, bool value_high)
{
        struct device *dev = &ggc->gbphy_dev->dev;
        struct gb_gpio_set_value_request request;
        int ret;

        request.which = which;
        request.value = value_high ? 1 : 0;
        ret = gb_operation_sync(ggc->connection, GB_GPIO_TYPE_SET_VALUE,
                                &request, sizeof(request), NULL, 0);
        if (ret) {
                dev_err(dev, "failed to set value of gpio %u\n", which);
                return ret;
        }

        ggc->lines[which].value = request.value;

        return 0;
}

static int gb_gpio_set_debounce_operation(struct gb_gpio_controller *ggc,
                                          u8 which, u16 debounce_usec)
{
        struct gb_gpio_set_debounce_request request;
        int ret;

        request.which = which;
        request.usec = cpu_to_le16(debounce_usec);
        ret = gb_operation_sync(ggc->connection, GB_GPIO_TYPE_SET_DEBOUNCE,
                                &request, sizeof(request), NULL, 0);
        if (!ret)
                ggc->lines[which].debounce_usec = debounce_usec;
        return ret;
}

static void _gb_gpio_irq_mask(struct gb_gpio_controller *ggc, u8 hwirq)
{
        struct device *dev = &ggc->gbphy_dev->dev;
        struct gb_gpio_irq_mask_request request;
        int ret;

        request.which = hwirq;
        ret = gb_operation_sync(ggc->connection,
                                GB_GPIO_TYPE_IRQ_MASK,
                                &request, sizeof(request), NULL, 0);
        if (ret)
                dev_err(dev, "failed to mask irq: %d\n", ret);
}

static void _gb_gpio_irq_unmask(struct gb_gpio_controller *ggc, u8 hwirq)
{
        struct device *dev = &ggc->gbphy_dev->dev;
        struct gb_gpio_irq_unmask_request request;
        int ret;

        request.which = hwirq;
        ret = gb_operation_sync(ggc->connection,
                                GB_GPIO_TYPE_IRQ_UNMASK,
                                &request, sizeof(request), NULL, 0);
        if (ret)
                dev_err(dev, "failed to unmask irq: %d\n", ret);
}

static void _gb_gpio_irq_set_type(struct gb_gpio_controller *ggc,
                                  u8 hwirq, u8 type)
{
        struct device *dev = &ggc->gbphy_dev->dev;
        struct gb_gpio_irq_type_request request;
        int ret;

        request.which = hwirq;
        request.type = type;

        ret = gb_operation_sync(ggc->connection,
                                GB_GPIO_TYPE_IRQ_TYPE,
                                &request, sizeof(request), NULL, 0);
        if (ret)
                dev_err(dev, "failed to set irq type: %d\n", ret);
}

static void gb_gpio_irq_mask(struct irq_data *d)
{
        struct gpio_chip *chip = irq_data_to_gpio_chip(d);
        struct gb_gpio_controller *ggc = gpiochip_get_data(chip);
        struct gb_gpio_line *line = &ggc->lines[d->hwirq];

        line->masked = true;
        line->masked_pending = true;
}

static void gb_gpio_irq_unmask(struct irq_data *d)
{
        struct gpio_chip *chip = irq_data_to_gpio_chip(d);
        struct gb_gpio_controller *ggc = gpiochip_get_data(chip);
        struct gb_gpio_line *line = &ggc->lines[d->hwirq];

        line->masked = false;
        line->masked_pending = true;
}

static int gb_gpio_irq_set_type(struct irq_data *d, unsigned int type)
{
        struct gpio_chip *chip = irq_data_to_gpio_chip(d);
        struct gb_gpio_controller *ggc = gpiochip_get_data(chip);
        struct gb_gpio_line *line = &ggc->lines[d->hwirq];
        struct device *dev = &ggc->gbphy_dev->dev;
        u8 irq_type;

        switch (type) {
        case IRQ_TYPE_NONE:
                irq_type = GB_GPIO_IRQ_TYPE_NONE;
                break;
        case IRQ_TYPE_EDGE_RISING:
                irq_type = GB_GPIO_IRQ_TYPE_EDGE_RISING;
                break;
        case IRQ_TYPE_EDGE_FALLING:
                irq_type = GB_GPIO_IRQ_TYPE_EDGE_FALLING;
                break;
        case IRQ_TYPE_EDGE_BOTH:
                irq_type = GB_GPIO_IRQ_TYPE_EDGE_BOTH;
                break;
        case IRQ_TYPE_LEVEL_LOW:
                irq_type = GB_GPIO_IRQ_TYPE_LEVEL_LOW;
                break;
        case IRQ_TYPE_LEVEL_HIGH:
                irq_type = GB_GPIO_IRQ_TYPE_LEVEL_HIGH;
                break;
        default:
                dev_err(dev, "unsupported irq type: %u\n", type);
                return -EINVAL;
        }

        line->irq_type = irq_type;
        line->irq_type_pending = true;

        return 0;
}

static void gb_gpio_irq_bus_lock(struct irq_data *d)
{
        struct gpio_chip *chip = irq_data_to_gpio_chip(d);
        struct gb_gpio_controller *ggc = gpiochip_get_data(chip);

        mutex_lock(&ggc->irq_lock);
}

static void gb_gpio_irq_bus_sync_unlock(struct irq_data *d)
{
        struct gpio_chip *chip = irq_data_to_gpio_chip(d);
        struct gb_gpio_controller *ggc = gpiochip_get_data(chip);
        struct gb_gpio_line *line = &ggc->lines[d->hwirq];

        if (line->irq_type_pending) {
                _gb_gpio_irq_set_type(ggc, d->hwirq, line->irq_type);
                line->irq_type_pending = false;
        }

        if (line->masked_pending) {
                if (line->masked)
                        _gb_gpio_irq_mask(ggc, d->hwirq);
                else
                        _gb_gpio_irq_unmask(ggc, d->hwirq);
                line->masked_pending = false;
        }

        mutex_unlock(&ggc->irq_lock);
}

static int gb_gpio_request_handler(struct gb_operation *op)
{
        struct gb_connection *connection = op->connection;
        struct gb_gpio_controller *ggc = gb_connection_get_data(connection);
        struct device *dev = &ggc->gbphy_dev->dev;
        struct gb_message *request;
        struct gb_gpio_irq_event_request *event;
        u8 type = op->type;
        int irq, ret;

        if (type != GB_GPIO_TYPE_IRQ_EVENT) {
                dev_err(dev, "unsupported unsolicited request: %u\n", type);
                return -EINVAL;
        }

        request = op->request;

        if (request->payload_size < sizeof(*event)) {
                dev_err(dev, "short event received (%zu < %zu)\n",
                        request->payload_size, sizeof(*event));
                return -EINVAL;
        }

        event = request->payload;
        if (event->which > ggc->line_max) {
                dev_err(dev, "invalid hw irq: %d\n", event->which);
                return -EINVAL;
        }

        irq = irq_find_mapping(ggc->chip.irq.domain, event->which);
        if (!irq) {
                dev_err(dev, "failed to find IRQ\n");
                return -EINVAL;
        }

        ret = generic_handle_irq_safe(irq);
        if (ret)
                dev_err(dev, "failed to invoke irq handler\n");

        return ret;
}

static int gb_gpio_request(struct gpio_chip *chip, unsigned int offset)
{
        struct gb_gpio_controller *ggc = gpiochip_get_data(chip);

        return gb_gpio_activate_operation(ggc, (u8)offset);
}

static void gb_gpio_free(struct gpio_chip *chip, unsigned int offset)
{
        struct gb_gpio_controller *ggc = gpiochip_get_data(chip);

        gb_gpio_deactivate_operation(ggc, (u8)offset);
}

static int gb_gpio_get_direction(struct gpio_chip *chip, unsigned int offset)
{
        struct gb_gpio_controller *ggc = gpiochip_get_data(chip);
        u8 which;
        int ret;

        which = (u8)offset;
        ret = gb_gpio_get_direction_operation(ggc, which);
        if (ret)
                return ret;

        return ggc->lines[which].direction ? 1 : 0;
}

static int gb_gpio_direction_input(struct gpio_chip *chip, unsigned int offset)
{
        struct gb_gpio_controller *ggc = gpiochip_get_data(chip);

        return gb_gpio_direction_in_operation(ggc, (u8)offset);
}

static int gb_gpio_direction_output(struct gpio_chip *chip, unsigned int offset,
                                    int value)
{
        struct gb_gpio_controller *ggc = gpiochip_get_data(chip);

        return gb_gpio_direction_out_operation(ggc, (u8)offset, !!value);
}

static int gb_gpio_get(struct gpio_chip *chip, unsigned int offset)
{
        struct gb_gpio_controller *ggc = gpiochip_get_data(chip);
        u8 which;
        int ret;

        which = (u8)offset;
        ret = gb_gpio_get_value_operation(ggc, which);
        if (ret)
                return ret;

        return ggc->lines[which].value;
}

static int gb_gpio_set(struct gpio_chip *chip, unsigned int offset, int value)
{
        struct gb_gpio_controller *ggc = gpiochip_get_data(chip);

        return gb_gpio_set_value_operation(ggc, (u8)offset, !!value);
}

static int gb_gpio_set_config(struct gpio_chip *chip, unsigned int offset,
                              unsigned long config)
{
        struct gb_gpio_controller *ggc = gpiochip_get_data(chip);
        u32 debounce;

        if (pinconf_to_config_param(config) != PIN_CONFIG_INPUT_DEBOUNCE)
                return -ENOTSUPP;

        debounce = pinconf_to_config_argument(config);
        if (debounce > U16_MAX)
                return -EINVAL;

        return gb_gpio_set_debounce_operation(ggc, (u8)offset, (u16)debounce);
}

static int gb_gpio_controller_setup(struct gb_gpio_controller *ggc)
{
        int ret;

        /* Now find out how many lines there are */
        ret = gb_gpio_line_count_operation(ggc);
        if (ret)
                return ret;

        ggc->lines = kzalloc_objs(*ggc->lines, ggc->line_max + 1);
        if (!ggc->lines)
                return -ENOMEM;

        return ret;
}

static int gb_gpio_probe(struct gbphy_device *gbphy_dev,
                         const struct gbphy_device_id *id)
{
        struct gb_connection *connection;
        struct gb_gpio_controller *ggc;
        struct gpio_chip *gpio;
        struct gpio_irq_chip *girq;
        struct irq_chip *irqc;
        int ret;

        ggc = kzalloc_obj(*ggc);
        if (!ggc)
                return -ENOMEM;

        connection =
                gb_connection_create(gbphy_dev->bundle,
                                     le16_to_cpu(gbphy_dev->cport_desc->id),
                                     gb_gpio_request_handler);
        if (IS_ERR(connection)) {
                ret = PTR_ERR(connection);
                goto exit_ggc_free;
        }

        ggc->connection = connection;
        gb_connection_set_data(connection, ggc);
        ggc->gbphy_dev = gbphy_dev;
        gb_gbphy_set_data(gbphy_dev, ggc);

        ret = gb_connection_enable_tx(connection);
        if (ret)
                goto exit_connection_destroy;

        ret = gb_gpio_controller_setup(ggc);
        if (ret)
                goto exit_connection_disable;

        irqc = &ggc->irqc;
        irqc->irq_mask = gb_gpio_irq_mask;
        irqc->irq_unmask = gb_gpio_irq_unmask;
        irqc->irq_set_type = gb_gpio_irq_set_type;
        irqc->irq_bus_lock = gb_gpio_irq_bus_lock;
        irqc->irq_bus_sync_unlock = gb_gpio_irq_bus_sync_unlock;
        irqc->name = "greybus_gpio";

        mutex_init(&ggc->irq_lock);

        gpio = &ggc->chip;

        gpio->label = "greybus_gpio";
        gpio->parent = &gbphy_dev->dev;
        gpio->owner = THIS_MODULE;

        gpio->request = gb_gpio_request;
        gpio->free = gb_gpio_free;
        gpio->get_direction = gb_gpio_get_direction;
        gpio->direction_input = gb_gpio_direction_input;
        gpio->direction_output = gb_gpio_direction_output;
        gpio->get = gb_gpio_get;
        gpio->set = gb_gpio_set;
        gpio->set_config = gb_gpio_set_config;
        gpio->base = -1;                /* Allocate base dynamically */
        gpio->ngpio = ggc->line_max + 1;
        gpio->can_sleep = true;

        girq = &gpio->irq;
        girq->chip = irqc;
        /* The event comes from the outside so no parent handler */
        girq->parent_handler = NULL;
        girq->num_parents = 0;
        girq->parents = NULL;
        girq->default_type = IRQ_TYPE_NONE;
        girq->handler = handle_level_irq;

        ret = gb_connection_enable(connection);
        if (ret)
                goto exit_line_free;

        ret = gpiochip_add_data(gpio, ggc);
        if (ret) {
                dev_err(&gbphy_dev->dev, "failed to add gpio chip: %d\n", ret);
                goto exit_line_free;
        }

        gbphy_runtime_put_autosuspend(gbphy_dev);
        return 0;

exit_line_free:
        kfree(ggc->lines);
exit_connection_disable:
        gb_connection_disable(connection);
exit_connection_destroy:
        gb_connection_destroy(connection);
exit_ggc_free:
        kfree(ggc);
        return ret;
}

static void gb_gpio_remove(struct gbphy_device *gbphy_dev)
{
        struct gb_gpio_controller *ggc = gb_gbphy_get_data(gbphy_dev);
        struct gb_connection *connection = ggc->connection;
        int ret;

        ret = gbphy_runtime_get_sync(gbphy_dev);
        if (ret)
                gbphy_runtime_get_noresume(gbphy_dev);

        gb_connection_disable_rx(connection);
        gpiochip_remove(&ggc->chip);
        gb_connection_disable(connection);
        gb_connection_destroy(connection);
        kfree(ggc->lines);
        kfree(ggc);
}

static const struct gbphy_device_id gb_gpio_id_table[] = {
        { GBPHY_PROTOCOL(GREYBUS_PROTOCOL_GPIO) },
        { },
};
MODULE_DEVICE_TABLE(gbphy, gb_gpio_id_table);

static struct gbphy_driver gpio_driver = {
        .name           = "gpio",
        .probe          = gb_gpio_probe,
        .remove         = gb_gpio_remove,
        .id_table       = gb_gpio_id_table,
};

module_gbphy_driver(gpio_driver);
MODULE_DESCRIPTION("GPIO Greybus driver");
MODULE_LICENSE("GPL v2");