// SPDX-License-Identifier: GPL-2.0-only
/*
 * Intel La Jolla Cove Adapter USB-GPIO driver
 *
 * Copyright (c) 2023, Intel Corporation.
 */

#include <linux/acpi.h>
#include <linux/auxiliary_bus.h>
#include <linux/bitfield.h>
#include <linux/bitops.h>
#include <linux/dev_printk.h>
#include <linux/gpio/driver.h>
#include <linux/irq.h>
#include <linux/kernel.h>
#include <linux/kref.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/usb/ljca.h>

/* GPIO commands */
#define LJCA_GPIO_CONFIG                1
#define LJCA_GPIO_READ                  2
#define LJCA_GPIO_WRITE                 3
#define LJCA_GPIO_INT_EVENT             4
#define LJCA_GPIO_INT_MASK              5
#define LJCA_GPIO_INT_UNMASK            6

#define LJCA_GPIO_CONF_DISABLE          BIT(0)
#define LJCA_GPIO_CONF_INPUT            BIT(1)
#define LJCA_GPIO_CONF_OUTPUT           BIT(2)
#define LJCA_GPIO_CONF_PULLUP           BIT(3)
#define LJCA_GPIO_CONF_PULLDOWN         BIT(4)
#define LJCA_GPIO_CONF_DEFAULT          BIT(5)
#define LJCA_GPIO_CONF_INTERRUPT        BIT(6)
#define LJCA_GPIO_INT_TYPE              BIT(7)

#define LJCA_GPIO_CONF_EDGE             FIELD_PREP(LJCA_GPIO_INT_TYPE, 1)
#define LJCA_GPIO_CONF_LEVEL            FIELD_PREP(LJCA_GPIO_INT_TYPE, 0)

/* Intentional overlap with PULLUP / PULLDOWN */
#define LJCA_GPIO_CONF_SET              BIT(3)
#define LJCA_GPIO_CONF_CLR              BIT(4)

#define LJCA_GPIO_BUF_SIZE              60u

struct ljca_gpio_op {
        u8 index;
        u8 value;
} __packed;

struct ljca_gpio_packet {
        u8 num;
        struct ljca_gpio_op item[] __counted_by(num);
} __packed;

struct ljca_gpio_dev {
        struct ljca_client *ljca;
        struct gpio_chip gc;
        struct ljca_gpio_info *gpio_info;
        DECLARE_BITMAP(unmasked_irqs, LJCA_MAX_GPIO_NUM);
        DECLARE_BITMAP(enabled_irqs, LJCA_MAX_GPIO_NUM);
        DECLARE_BITMAP(reenable_irqs, LJCA_MAX_GPIO_NUM);
        DECLARE_BITMAP(output_enabled, LJCA_MAX_GPIO_NUM);
        u8 *connect_mode;
        /* protect irq bus */
        struct mutex irq_lock;
        struct work_struct work;
        /* protect package transfer to hardware */
        struct mutex trans_lock;

        u8 obuf[LJCA_GPIO_BUF_SIZE];
        u8 ibuf[LJCA_GPIO_BUF_SIZE];
};

static int ljca_gpio_config(struct ljca_gpio_dev *ljca_gpio, u8 gpio_id,
                            u8 config)
{
        struct ljca_gpio_packet *packet =
                                (struct ljca_gpio_packet *)ljca_gpio->obuf;
        int ret;

        mutex_lock(&ljca_gpio->trans_lock);
        packet->num = 1;
        packet->item[0].index = gpio_id;
        packet->item[0].value = config | ljca_gpio->connect_mode[gpio_id];

        ret = ljca_transfer(ljca_gpio->ljca, LJCA_GPIO_CONFIG, (u8 *)packet,
                            struct_size(packet, item, packet->num), NULL, 0);
        mutex_unlock(&ljca_gpio->trans_lock);

        return ret < 0 ? ret : 0;
}

static int ljca_gpio_read(struct ljca_gpio_dev *ljca_gpio, u8 gpio_id)
{
        struct ljca_gpio_packet *ack_packet =
                                (struct ljca_gpio_packet *)ljca_gpio->ibuf;
        struct ljca_gpio_packet *packet =
                                (struct ljca_gpio_packet *)ljca_gpio->obuf;
        int ret;

        mutex_lock(&ljca_gpio->trans_lock);
        packet->num = 1;
        packet->item[0].index = gpio_id;
        ret = ljca_transfer(ljca_gpio->ljca, LJCA_GPIO_READ, (u8 *)packet,
                            struct_size(packet, item, packet->num),
                            ljca_gpio->ibuf, LJCA_GPIO_BUF_SIZE);

        if (ret <= 0 || ack_packet->num != packet->num) {
                dev_err(&ljca_gpio->ljca->auxdev.dev,
                        "read package error, gpio_id: %u num: %u ret: %d\n",
                        gpio_id, ack_packet->num, ret);
                ret = ret < 0 ? ret : -EIO;
        }
        mutex_unlock(&ljca_gpio->trans_lock);

        return ret < 0 ? ret : ack_packet->item[0].value > 0;
}

static int ljca_gpio_write(struct ljca_gpio_dev *ljca_gpio, u8 gpio_id, int value)
{
        struct ljca_gpio_packet *packet =
                        (struct ljca_gpio_packet *)ljca_gpio->obuf;
        int ret;

        mutex_lock(&ljca_gpio->trans_lock);
        packet->num = 1;
        packet->item[0].index = gpio_id;
        packet->item[0].value = value & 1;

        ret = ljca_transfer(ljca_gpio->ljca, LJCA_GPIO_WRITE, (u8 *)packet,
                            struct_size(packet, item, packet->num), NULL, 0);
        mutex_unlock(&ljca_gpio->trans_lock);

        return ret < 0 ? ret : 0;
}

static int ljca_gpio_get_value(struct gpio_chip *chip, unsigned int offset)
{
        struct ljca_gpio_dev *ljca_gpio = gpiochip_get_data(chip);

        return ljca_gpio_read(ljca_gpio, offset);
}

static int ljca_gpio_set_value(struct gpio_chip *chip, unsigned int offset,
                               int val)
{
        struct ljca_gpio_dev *ljca_gpio = gpiochip_get_data(chip);
        int ret;

        ret = ljca_gpio_write(ljca_gpio, offset, val);
        if (ret)
                dev_err(chip->parent,
                        "set value failed offset: %u val: %d ret: %d\n",
                        offset, val, ret);

        return ret;
}

static int ljca_gpio_direction_input(struct gpio_chip *chip, unsigned int offset)
{
        struct ljca_gpio_dev *ljca_gpio = gpiochip_get_data(chip);
        u8 config = LJCA_GPIO_CONF_INPUT | LJCA_GPIO_CONF_CLR;
        int ret;

        ret = ljca_gpio_config(ljca_gpio, offset, config);
        if (ret)
                return ret;

        clear_bit(offset, ljca_gpio->output_enabled);

        return 0;
}

static int ljca_gpio_direction_output(struct gpio_chip *chip,
                                      unsigned int offset, int val)
{
        struct ljca_gpio_dev *ljca_gpio = gpiochip_get_data(chip);
        u8 config = LJCA_GPIO_CONF_OUTPUT | LJCA_GPIO_CONF_CLR;
        int ret;

        ret = ljca_gpio_config(ljca_gpio, offset, config);
        if (ret)
                return ret;

        ret = ljca_gpio_set_value(chip, offset, val);
        if (ret)
                return ret;

        set_bit(offset, ljca_gpio->output_enabled);

        return 0;
}

static int ljca_gpio_get_direction(struct gpio_chip *chip, unsigned int offset)
{
        struct ljca_gpio_dev *ljca_gpio = gpiochip_get_data(chip);

        if (test_bit(offset, ljca_gpio->output_enabled))
                return GPIO_LINE_DIRECTION_OUT;

        return GPIO_LINE_DIRECTION_IN;
}

static int ljca_gpio_set_config(struct gpio_chip *chip, unsigned int offset,
                                unsigned long config)
{
        struct ljca_gpio_dev *ljca_gpio = gpiochip_get_data(chip);

        ljca_gpio->connect_mode[offset] = 0;
        switch (pinconf_to_config_param(config)) {
        case PIN_CONFIG_BIAS_PULL_UP:
                ljca_gpio->connect_mode[offset] |= LJCA_GPIO_CONF_PULLUP;
                break;
        case PIN_CONFIG_BIAS_PULL_DOWN:
                ljca_gpio->connect_mode[offset] |= LJCA_GPIO_CONF_PULLDOWN;
                break;
        case PIN_CONFIG_DRIVE_PUSH_PULL:
        case PIN_CONFIG_PERSIST_STATE:
                break;
        default:
                return -ENOTSUPP;
        }

        return 0;
}

static int ljca_gpio_init_valid_mask(struct gpio_chip *chip,
                                     unsigned long *valid_mask,
                                     unsigned int ngpios)
{
        struct ljca_gpio_dev *ljca_gpio = gpiochip_get_data(chip);

        WARN_ON_ONCE(ngpios != ljca_gpio->gpio_info->num);
        bitmap_copy(valid_mask, ljca_gpio->gpio_info->valid_pin_map, ngpios);

        return 0;
}

static void ljca_gpio_irq_init_valid_mask(struct gpio_chip *chip,
                                          unsigned long *valid_mask,
                                          unsigned int ngpios)
{
        ljca_gpio_init_valid_mask(chip, valid_mask, ngpios);
}

static int ljca_enable_irq(struct ljca_gpio_dev *ljca_gpio, int gpio_id,
                           bool enable)
{
        struct ljca_gpio_packet *packet =
                        (struct ljca_gpio_packet *)ljca_gpio->obuf;
        int ret;

        mutex_lock(&ljca_gpio->trans_lock);
        packet->num = 1;
        packet->item[0].index = gpio_id;
        packet->item[0].value = 0;

        ret = ljca_transfer(ljca_gpio->ljca,
                            enable ? LJCA_GPIO_INT_UNMASK : LJCA_GPIO_INT_MASK,
                            (u8 *)packet, struct_size(packet, item, packet->num),
                            NULL, 0);
        mutex_unlock(&ljca_gpio->trans_lock);

        return ret < 0 ? ret : 0;
}

static void ljca_gpio_async(struct work_struct *work)
{
        struct ljca_gpio_dev *ljca_gpio =
                        container_of(work, struct ljca_gpio_dev, work);
        int gpio_id, unmasked;

        for_each_set_bit(gpio_id, ljca_gpio->reenable_irqs, ljca_gpio->gc.ngpio) {
                clear_bit(gpio_id, ljca_gpio->reenable_irqs);
                unmasked = test_bit(gpio_id, ljca_gpio->unmasked_irqs);
                if (unmasked)
                        ljca_enable_irq(ljca_gpio, gpio_id, true);
        }
}

static void ljca_gpio_event_cb(void *context, u8 cmd, const void *evt_data,
                               int len)
{
        const struct ljca_gpio_packet *packet = evt_data;
        struct ljca_gpio_dev *ljca_gpio = context;
        int i;

        if (cmd != LJCA_GPIO_INT_EVENT)
                return;

        for (i = 0; i < packet->num; i++) {
                generic_handle_domain_irq(ljca_gpio->gc.irq.domain,
                                        packet->item[i].index);
                set_bit(packet->item[i].index, ljca_gpio->reenable_irqs);
        }

        schedule_work(&ljca_gpio->work);
}

static void ljca_irq_unmask(struct irq_data *irqd)
{
        struct gpio_chip *gc = irq_data_get_irq_chip_data(irqd);
        struct ljca_gpio_dev *ljca_gpio = gpiochip_get_data(gc);
        int gpio_id = irqd_to_hwirq(irqd);

        gpiochip_enable_irq(gc, gpio_id);
        set_bit(gpio_id, ljca_gpio->unmasked_irqs);
}

static void ljca_irq_mask(struct irq_data *irqd)
{
        struct gpio_chip *gc = irq_data_get_irq_chip_data(irqd);
        struct ljca_gpio_dev *ljca_gpio = gpiochip_get_data(gc);
        int gpio_id = irqd_to_hwirq(irqd);

        clear_bit(gpio_id, ljca_gpio->unmasked_irqs);
        gpiochip_disable_irq(gc, gpio_id);
}

static int ljca_irq_set_type(struct irq_data *irqd, unsigned int type)
{
        struct gpio_chip *gc = irq_data_get_irq_chip_data(irqd);
        struct ljca_gpio_dev *ljca_gpio = gpiochip_get_data(gc);
        int gpio_id = irqd_to_hwirq(irqd);

        ljca_gpio->connect_mode[gpio_id] = LJCA_GPIO_CONF_INTERRUPT;
        switch (type) {
        case IRQ_TYPE_LEVEL_HIGH:
                ljca_gpio->connect_mode[gpio_id] |=
                        (LJCA_GPIO_CONF_LEVEL | LJCA_GPIO_CONF_PULLUP);
                break;
        case IRQ_TYPE_LEVEL_LOW:
                ljca_gpio->connect_mode[gpio_id] |=
                        (LJCA_GPIO_CONF_LEVEL | LJCA_GPIO_CONF_PULLDOWN);
                break;
        case IRQ_TYPE_EDGE_BOTH:
                break;
        case IRQ_TYPE_EDGE_RISING:
                ljca_gpio->connect_mode[gpio_id] |=
                        (LJCA_GPIO_CONF_EDGE | LJCA_GPIO_CONF_PULLUP);
                break;
        case IRQ_TYPE_EDGE_FALLING:
                ljca_gpio->connect_mode[gpio_id] |=
                        (LJCA_GPIO_CONF_EDGE | LJCA_GPIO_CONF_PULLDOWN);
                break;
        default:
                return -EINVAL;
        }

        return 0;
}

static void ljca_irq_bus_lock(struct irq_data *irqd)
{
        struct gpio_chip *gc = irq_data_get_irq_chip_data(irqd);
        struct ljca_gpio_dev *ljca_gpio = gpiochip_get_data(gc);

        mutex_lock(&ljca_gpio->irq_lock);
}

static void ljca_irq_bus_unlock(struct irq_data *irqd)
{
        struct gpio_chip *gc = irq_data_get_irq_chip_data(irqd);
        struct ljca_gpio_dev *ljca_gpio = gpiochip_get_data(gc);
        int gpio_id = irqd_to_hwirq(irqd);
        int enabled, unmasked;

        enabled = test_bit(gpio_id, ljca_gpio->enabled_irqs);
        unmasked = test_bit(gpio_id, ljca_gpio->unmasked_irqs);

        if (enabled != unmasked) {
                if (unmasked) {
                        ljca_gpio_config(ljca_gpio, gpio_id, 0);
                        ljca_enable_irq(ljca_gpio, gpio_id, true);
                        set_bit(gpio_id, ljca_gpio->enabled_irqs);
                } else {
                        ljca_enable_irq(ljca_gpio, gpio_id, false);
                        clear_bit(gpio_id, ljca_gpio->enabled_irqs);
                }
        }

        mutex_unlock(&ljca_gpio->irq_lock);
}

static const struct irq_chip ljca_gpio_irqchip = {
        .name = "ljca-irq",
        .irq_mask = ljca_irq_mask,
        .irq_unmask = ljca_irq_unmask,
        .irq_set_type = ljca_irq_set_type,
        .irq_bus_lock = ljca_irq_bus_lock,
        .irq_bus_sync_unlock = ljca_irq_bus_unlock,
        .flags = IRQCHIP_IMMUTABLE,
        GPIOCHIP_IRQ_RESOURCE_HELPERS,
};

static int ljca_gpio_probe(struct auxiliary_device *auxdev,
                           const struct auxiliary_device_id *aux_dev_id)
{
        struct ljca_client *ljca = auxiliary_dev_to_ljca_client(auxdev);
        struct ljca_gpio_dev *ljca_gpio;
        struct gpio_irq_chip *girq;
        int ret;

        ljca_gpio = devm_kzalloc(&auxdev->dev, sizeof(*ljca_gpio), GFP_KERNEL);
        if (!ljca_gpio)
                return -ENOMEM;

        ljca_gpio->ljca = ljca;
        ljca_gpio->gpio_info = dev_get_platdata(&auxdev->dev);
        ljca_gpio->connect_mode = devm_kcalloc(&auxdev->dev,
                                               ljca_gpio->gpio_info->num,
                                               sizeof(*ljca_gpio->connect_mode),
                                               GFP_KERNEL);
        if (!ljca_gpio->connect_mode)
                return -ENOMEM;

        ret = devm_mutex_init(&auxdev->dev, &ljca_gpio->irq_lock);
        if (ret)
                return ret;

        ret = devm_mutex_init(&auxdev->dev, &ljca_gpio->trans_lock);
        if (ret)
                return ret;

        ljca_gpio->gc.direction_input = ljca_gpio_direction_input;
        ljca_gpio->gc.direction_output = ljca_gpio_direction_output;
        ljca_gpio->gc.get_direction = ljca_gpio_get_direction;
        ljca_gpio->gc.get = ljca_gpio_get_value;
        ljca_gpio->gc.set = ljca_gpio_set_value;
        ljca_gpio->gc.set_config = ljca_gpio_set_config;
        ljca_gpio->gc.init_valid_mask = ljca_gpio_init_valid_mask;
        ljca_gpio->gc.can_sleep = true;
        ljca_gpio->gc.parent = &auxdev->dev;

        ljca_gpio->gc.base = -1;
        ljca_gpio->gc.ngpio = ljca_gpio->gpio_info->num;
        ljca_gpio->gc.label = ACPI_COMPANION(&auxdev->dev) ?
                              acpi_dev_name(ACPI_COMPANION(&auxdev->dev)) :
                              dev_name(&auxdev->dev);
        ljca_gpio->gc.owner = THIS_MODULE;

        auxiliary_set_drvdata(auxdev, ljca_gpio);
        ljca_register_event_cb(ljca, ljca_gpio_event_cb, ljca_gpio);

        girq = &ljca_gpio->gc.irq;
        gpio_irq_chip_set_chip(girq, &ljca_gpio_irqchip);
        girq->parent_handler = NULL;
        girq->num_parents = 0;
        girq->parents = NULL;
        girq->default_type = IRQ_TYPE_NONE;
        girq->handler = handle_simple_irq;
        girq->init_valid_mask = ljca_gpio_irq_init_valid_mask;

        INIT_WORK(&ljca_gpio->work, ljca_gpio_async);
        ret = gpiochip_add_data(&ljca_gpio->gc, ljca_gpio);
        if (ret)
                ljca_unregister_event_cb(ljca);

        return ret;
}

static void ljca_gpio_remove(struct auxiliary_device *auxdev)
{
        struct ljca_gpio_dev *ljca_gpio = auxiliary_get_drvdata(auxdev);

        gpiochip_remove(&ljca_gpio->gc);
        ljca_unregister_event_cb(ljca_gpio->ljca);
        cancel_work_sync(&ljca_gpio->work);
}

static const struct auxiliary_device_id ljca_gpio_id_table[] = {
        { "usb_ljca.ljca-gpio", 0 },
        { /* sentinel */ },
};
MODULE_DEVICE_TABLE(auxiliary, ljca_gpio_id_table);

static struct auxiliary_driver ljca_gpio_driver = {
        .probe = ljca_gpio_probe,
        .remove = ljca_gpio_remove,
        .id_table = ljca_gpio_id_table,
};
module_auxiliary_driver(ljca_gpio_driver);

MODULE_AUTHOR("Wentong Wu <wentong.wu@intel.com>");
MODULE_AUTHOR("Zhifeng Wang <zhifeng.wang@intel.com>");
MODULE_AUTHOR("Lixu Zhang <lixu.zhang@intel.com>");
MODULE_DESCRIPTION("Intel La Jolla Cove Adapter USB-GPIO driver");
MODULE_LICENSE("GPL");
MODULE_IMPORT_NS("LJCA");