// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2022-2024, Linaro Ltd
 * Authors:
 *    Bjorn Andersson
 *    Dmitry Baryshkov
 */
#include <linux/auxiliary_bus.h>
#include <linux/cleanup.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/irqreturn.h>
#include <linux/lockdep.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/notifier.h>
#include <linux/slab.h>
#include <linux/platform_data/lenovo-yoga-c630.h>

#define LENOVO_EC_RESPONSE_REG          0x01
#define LENOVO_EC_REQUEST_REG           0x02

#define LENOVO_EC_UCSI_WRITE            0x20
#define LENOVO_EC_UCSI_READ             0x21

#define LENOVO_EC_READ_REG              0xb0
#define LENOVO_EC_REQUEST_NEXT_EVENT    0x84

#define LENOVO_EC_UCSI_VERSION          0x20

struct yoga_c630_ec {
        struct i2c_client *client;
        struct mutex lock;
        struct blocking_notifier_head notifier_list;
};

static int yoga_c630_ec_request(struct yoga_c630_ec *ec, u8 *req, size_t req_len,
                                u8 *resp, size_t resp_len)
{
        int ret;

        lockdep_assert_held(&ec->lock);

        ret = i2c_smbus_write_i2c_block_data(ec->client, LENOVO_EC_REQUEST_REG,
                                             req_len, req);
        if (ret < 0)
                return ret;

        return i2c_smbus_read_i2c_block_data(ec->client, LENOVO_EC_RESPONSE_REG,
                                             resp_len, resp);
}

int yoga_c630_ec_read8(struct yoga_c630_ec *ec, u8 addr)
{
        u8 req[2] = { LENOVO_EC_READ_REG, };
        int ret;
        u8 val;

        guard(mutex)(&ec->lock);

        req[1] = addr;
        ret = yoga_c630_ec_request(ec, req, sizeof(req), &val, 1);
        if (ret < 0)
                return ret;

        return val;
}
EXPORT_SYMBOL_GPL(yoga_c630_ec_read8);

int yoga_c630_ec_read16(struct yoga_c630_ec *ec, u8 addr)
{
        u8 req[2] = { LENOVO_EC_READ_REG, };
        int ret;
        u8 msb;
        u8 lsb;

        /* don't overflow the address */
        if (addr == 0xff)
                return -EINVAL;

        guard(mutex)(&ec->lock);

        req[1] = addr;
        ret = yoga_c630_ec_request(ec, req, sizeof(req), &lsb, 1);
        if (ret < 0)
                return ret;

        req[1] = addr + 1;
        ret = yoga_c630_ec_request(ec, req, sizeof(req), &msb, 1);
        if (ret < 0)
                return ret;

        return msb << 8 | lsb;
}
EXPORT_SYMBOL_GPL(yoga_c630_ec_read16);

u16 yoga_c630_ec_ucsi_get_version(struct yoga_c630_ec *ec)
{
        u8 req[3] = { 0xb3, 0xf2, };
        int ret;
        u8 msb;
        u8 lsb;

        guard(mutex)(&ec->lock);

        req[2] = LENOVO_EC_UCSI_VERSION;
        ret = yoga_c630_ec_request(ec, req, sizeof(req), &lsb, 1);
        if (ret < 0)
                return ret;

        req[2] = LENOVO_EC_UCSI_VERSION + 1;
        ret = yoga_c630_ec_request(ec, req, sizeof(req), &msb, 1);
        if (ret < 0)
                return ret;

        return msb << 8 | lsb;
}
EXPORT_SYMBOL_GPL(yoga_c630_ec_ucsi_get_version);

int yoga_c630_ec_ucsi_write(struct yoga_c630_ec *ec,
                            const u8 req[YOGA_C630_UCSI_WRITE_SIZE])
{
        int ret;

        mutex_lock(&ec->lock);
        ret = i2c_smbus_write_i2c_block_data(ec->client, LENOVO_EC_UCSI_WRITE,
                                             YOGA_C630_UCSI_WRITE_SIZE, req);
        mutex_unlock(&ec->lock);

        return ret < 0 ? ret : 0;
}
EXPORT_SYMBOL_GPL(yoga_c630_ec_ucsi_write);

int yoga_c630_ec_ucsi_read(struct yoga_c630_ec *ec,
                           u8 resp[YOGA_C630_UCSI_READ_SIZE])
{
        int ret;

        mutex_lock(&ec->lock);
        ret = i2c_smbus_read_i2c_block_data(ec->client, LENOVO_EC_UCSI_READ,
                                            YOGA_C630_UCSI_READ_SIZE, resp);
        mutex_unlock(&ec->lock);

        return ret < 0 ? ret : 0;
}
EXPORT_SYMBOL_GPL(yoga_c630_ec_ucsi_read);

static irqreturn_t yoga_c630_ec_thread_intr(int irq, void *data)
{
        u8 req[] = { LENOVO_EC_REQUEST_NEXT_EVENT };
        struct yoga_c630_ec *ec = data;
        u8 event;
        int ret;

        mutex_lock(&ec->lock);
        ret = yoga_c630_ec_request(ec, req, sizeof(req), &event, 1);
        mutex_unlock(&ec->lock);
        if (ret < 0)
                return IRQ_HANDLED;

        blocking_notifier_call_chain(&ec->notifier_list, event, ec);

        return IRQ_HANDLED;
}

/**
 * yoga_c630_ec_register_notify - Register a notifier callback for EC events.
 * @ec: Yoga C630 EC
 * @nb: Notifier block pointer to register
 *
 * Return: 0 on success or negative error code.
 */
int yoga_c630_ec_register_notify(struct yoga_c630_ec *ec, struct notifier_block *nb)
{
        return blocking_notifier_chain_register(&ec->notifier_list, nb);
}
EXPORT_SYMBOL_GPL(yoga_c630_ec_register_notify);

/**
 * yoga_c630_ec_unregister_notify - Unregister notifier callback for EC events.
 * @ec: Yoga C630 EC
 * @nb: Notifier block pointer to unregister
 *
 * Unregister a notifier callback that was previously registered with
 * yoga_c630_ec_register_notify().
 */
void yoga_c630_ec_unregister_notify(struct yoga_c630_ec *ec, struct notifier_block *nb)
{
        blocking_notifier_chain_unregister(&ec->notifier_list, nb);
}
EXPORT_SYMBOL_GPL(yoga_c630_ec_unregister_notify);

static int yoga_c630_aux_init(struct device *parent, const char *name,
                              struct yoga_c630_ec *ec)
{
        struct auxiliary_device *adev;

        adev = devm_auxiliary_device_create(parent, name, ec);
        if (!adev)
                return -ENODEV;

        return 0;
}

static int yoga_c630_ec_probe(struct i2c_client *client)
{
        struct device *dev = &client->dev;
        struct yoga_c630_ec *ec;
        int ret;

        ec = devm_kzalloc(dev, sizeof(*ec), GFP_KERNEL);
        if (!ec)
                return -ENOMEM;

        mutex_init(&ec->lock);
        ec->client = client;
        BLOCKING_INIT_NOTIFIER_HEAD(&ec->notifier_list);

        ret = devm_request_threaded_irq(dev, client->irq,
                                        NULL, yoga_c630_ec_thread_intr,
                                        IRQF_ONESHOT, "yoga_c630_ec", ec);
        if (ret < 0)
                return dev_err_probe(dev, ret, "unable to request irq\n");

        ret = yoga_c630_aux_init(dev, YOGA_C630_DEV_PSY, ec);
        if (ret)
                return ret;

        return yoga_c630_aux_init(dev, YOGA_C630_DEV_UCSI, ec);
}


static const struct of_device_id yoga_c630_ec_of_match[] = {
        { .compatible = "lenovo,yoga-c630-ec" },
        {}
};
MODULE_DEVICE_TABLE(of, yoga_c630_ec_of_match);

static const struct i2c_device_id yoga_c630_ec_i2c_id_table[] = {
        { "yoga-c630-ec", },
        {}
};
MODULE_DEVICE_TABLE(i2c, yoga_c630_ec_i2c_id_table);

static struct i2c_driver yoga_c630_ec_i2c_driver = {
        .driver = {
                .name = "yoga-c630-ec",
                .of_match_table = yoga_c630_ec_of_match
        },
        .probe = yoga_c630_ec_probe,
        .id_table = yoga_c630_ec_i2c_id_table,
};
module_i2c_driver(yoga_c630_ec_i2c_driver);

MODULE_DESCRIPTION("Lenovo Yoga C630 Embedded Controller");
MODULE_LICENSE("GPL");