// SPDX-License-Identifier: GPL-2.0
// I2C interface for ChromeOS Embedded Controller
//
// Copyright (C) 2012 Google, Inc

#include <linux/acpi.h>
#include <linux/delay.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/platform_data/cros_ec_commands.h>
#include <linux/platform_data/cros_ec_proto.h>
#include <linux/platform_device.h>
#include <linux/slab.h>

#include "cros_ec.h"

/*
 * Request format for protocol v3
 * byte 0       0xda (EC_COMMAND_PROTOCOL_3)
 * byte 1-8     struct ec_host_request
 * byte 10-     response data
 */
struct ec_host_request_i2c {
        /* Always 0xda to backward compatible with v2 struct */
        uint8_t  command_protocol;
        struct ec_host_request ec_request;
} __packed;


/*
 * Response format for protocol v3
 * byte 0       result code
 * byte 1       packet_length
 * byte 2-9     struct ec_host_response
 * byte 10-     response data
 */
struct ec_host_response_i2c {
        uint8_t result;
        uint8_t packet_length;
        struct ec_host_response ec_response;
} __packed;

static inline struct cros_ec_device *to_ec_dev(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);

        return i2c_get_clientdata(client);
}

static int cros_ec_pkt_xfer_i2c(struct cros_ec_device *ec_dev,
                                struct cros_ec_command *msg)
{
        struct i2c_client *client = ec_dev->priv;
        int ret = -ENOMEM;
        int i;
        int packet_len;
        u8 *out_buf = NULL;
        u8 *in_buf = NULL;
        u8 sum;
        struct i2c_msg i2c_msg[2];
        struct ec_host_response *ec_response;
        struct ec_host_request_i2c *ec_request_i2c;
        struct ec_host_response_i2c *ec_response_i2c;
        int request_header_size = sizeof(struct ec_host_request_i2c);
        int response_header_size = sizeof(struct ec_host_response_i2c);

        i2c_msg[0].addr = client->addr;
        i2c_msg[0].flags = 0;
        i2c_msg[1].addr = client->addr;
        i2c_msg[1].flags = I2C_M_RD;

        packet_len = msg->insize + response_header_size;
        if (packet_len > ec_dev->din_size) {
                ret = -EINVAL;
                goto done;
        }
        in_buf = ec_dev->din;
        i2c_msg[1].len = packet_len;
        i2c_msg[1].buf = (char *) in_buf;

        packet_len = msg->outsize + request_header_size;
        if (packet_len > ec_dev->dout_size) {
                ret = -EINVAL;
                goto done;
        }
        out_buf = ec_dev->dout;
        i2c_msg[0].len = packet_len;
        i2c_msg[0].buf = (char *) out_buf;

        /* create request data */
        ec_request_i2c = (struct ec_host_request_i2c *) out_buf;
        ec_request_i2c->command_protocol = EC_COMMAND_PROTOCOL_3;

        ec_dev->dout++;
        ret = cros_ec_prepare_tx(ec_dev, msg);
        if (ret < 0)
                goto done;
        ec_dev->dout--;

        /* send command to EC and read answer */
        ret = i2c_transfer(client->adapter, i2c_msg, 2);
        if (ret < 0) {
                dev_dbg(ec_dev->dev, "i2c transfer failed: %d\n", ret);
                goto done;
        } else if (ret != 2) {
                dev_err(ec_dev->dev, "failed to get response: %d\n", ret);
                ret = -EIO;
                goto done;
        }

        ec_response_i2c = (struct ec_host_response_i2c *) in_buf;
        msg->result = ec_response_i2c->result;
        ec_response = &ec_response_i2c->ec_response;

        switch (msg->result) {
        case EC_RES_SUCCESS:
                break;
        case EC_RES_IN_PROGRESS:
                ret = -EAGAIN;
                dev_dbg(ec_dev->dev, "command 0x%02x in progress\n",
                        msg->command);
                goto done;

        default:
                dev_dbg(ec_dev->dev, "command 0x%02x returned %d\n",
                        msg->command, msg->result);
                /*
                 * When we send v3 request to v2 ec, ec won't recognize the
                 * 0xda (EC_COMMAND_PROTOCOL_3) and will return with status
                 * EC_RES_INVALID_COMMAND with zero data length.
                 *
                 * In case of invalid command for v3 protocol the data length
                 * will be at least sizeof(struct ec_host_response)
                 */
                if (ec_response_i2c->result == EC_RES_INVALID_COMMAND &&
                    ec_response_i2c->packet_length == 0) {
                        ret = -EPROTONOSUPPORT;
                        goto done;
                }
        }

        if (ec_response_i2c->packet_length < sizeof(struct ec_host_response)) {
                dev_err(ec_dev->dev,
                        "response of %u bytes too short; not a full header\n",
                        ec_response_i2c->packet_length);
                ret = -EBADMSG;
                goto done;
        }

        if (msg->insize < ec_response->data_len) {
                dev_err(ec_dev->dev,
                        "response data size is too large: expected %u, got %u\n",
                        msg->insize,
                        ec_response->data_len);
                ret = -EMSGSIZE;
                goto done;
        }

        /* copy response packet payload and compute checksum */
        sum = 0;
        for (i = 0; i < sizeof(struct ec_host_response); i++)
                sum += ((u8 *)ec_response)[i];

        memcpy(msg->data,
               in_buf + response_header_size,
               ec_response->data_len);
        for (i = 0; i < ec_response->data_len; i++)
                sum += msg->data[i];

        /* All bytes should sum to zero */
        if (sum) {
                dev_err(ec_dev->dev, "bad packet checksum\n");
                ret = -EBADMSG;
                goto done;
        }

        ret = ec_response->data_len;

done:
        if (msg->command == EC_CMD_REBOOT_EC)
                msleep(EC_REBOOT_DELAY_MS);

        return ret;
}

static int cros_ec_cmd_xfer_i2c(struct cros_ec_device *ec_dev,
                                struct cros_ec_command *msg)
{
        struct i2c_client *client = ec_dev->priv;
        int ret = -ENOMEM;
        int i;
        int len;
        int packet_len;
        u8 *out_buf = NULL;
        u8 *in_buf = NULL;
        u8 sum;
        struct i2c_msg i2c_msg[2];

        i2c_msg[0].addr = client->addr;
        i2c_msg[0].flags = 0;
        i2c_msg[1].addr = client->addr;
        i2c_msg[1].flags = I2C_M_RD;

        /*
         * allocate larger packet (one byte for checksum, one byte for
         * length, and one for result code)
         */
        packet_len = msg->insize + 3;
        in_buf = kzalloc(packet_len, GFP_KERNEL);
        if (!in_buf)
                goto done;
        i2c_msg[1].len = packet_len;
        i2c_msg[1].buf = (char *)in_buf;

        /*
         * allocate larger packet (one byte for checksum, one for
         * command code, one for length, and one for command version)
         */
        packet_len = msg->outsize + 4;
        out_buf = kzalloc(packet_len, GFP_KERNEL);
        if (!out_buf)
                goto done;
        i2c_msg[0].len = packet_len;
        i2c_msg[0].buf = (char *)out_buf;

        out_buf[0] = EC_CMD_VERSION0 + msg->version;
        out_buf[1] = msg->command;
        out_buf[2] = msg->outsize;

        /* copy message payload and compute checksum */
        sum = out_buf[0] + out_buf[1] + out_buf[2];
        for (i = 0; i < msg->outsize; i++) {
                out_buf[3 + i] = msg->data[i];
                sum += out_buf[3 + i];
        }
        out_buf[3 + msg->outsize] = sum;

        /* send command to EC and read answer */
        ret = i2c_transfer(client->adapter, i2c_msg, 2);
        if (ret < 0) {
                dev_err(ec_dev->dev, "i2c transfer failed: %d\n", ret);
                goto done;
        } else if (ret != 2) {
                dev_err(ec_dev->dev, "failed to get response: %d\n", ret);
                ret = -EIO;
                goto done;
        }

        /* check response error code */
        msg->result = i2c_msg[1].buf[0];
        ret = cros_ec_check_result(ec_dev, msg);
        if (ret)
                goto done;

        len = in_buf[1];
        if (len > msg->insize) {
                dev_err(ec_dev->dev, "packet too long (%d bytes, expected %d)",
                        len, msg->insize);
                ret = -ENOSPC;
                goto done;
        }

        /* copy response packet payload and compute checksum */
        sum = in_buf[0] + in_buf[1];
        for (i = 0; i < len; i++) {
                msg->data[i] = in_buf[2 + i];
                sum += in_buf[2 + i];
        }
        dev_dbg(ec_dev->dev, "packet: %*ph, sum = %02x\n",
                i2c_msg[1].len, in_buf, sum);
        if (sum != in_buf[2 + len]) {
                dev_err(ec_dev->dev, "bad packet checksum\n");
                ret = -EBADMSG;
                goto done;
        }

        ret = len;
done:
        kfree(in_buf);
        kfree(out_buf);
        if (msg->command == EC_CMD_REBOOT_EC)
                msleep(EC_REBOOT_DELAY_MS);

        return ret;
}

static int cros_ec_i2c_probe(struct i2c_client *client)
{
        struct device *dev = &client->dev;
        struct cros_ec_device *ec_dev;
        int err;

        ec_dev = cros_ec_device_alloc(dev);
        if (!ec_dev)
                return -ENOMEM;

        i2c_set_clientdata(client, ec_dev);
        ec_dev->priv = client;
        ec_dev->irq = client->irq;
        ec_dev->cmd_xfer = cros_ec_cmd_xfer_i2c;
        ec_dev->pkt_xfer = cros_ec_pkt_xfer_i2c;
        ec_dev->phys_name = client->adapter->name;

        err = cros_ec_register(ec_dev);
        if (err) {
                dev_err(dev, "cannot register EC\n");
                return err;
        }

        return 0;
}

static void cros_ec_i2c_remove(struct i2c_client *client)
{
        struct cros_ec_device *ec_dev = i2c_get_clientdata(client);

        cros_ec_unregister(ec_dev);
}

#ifdef CONFIG_PM_SLEEP
static int cros_ec_i2c_suspend(struct device *dev)
{
        struct cros_ec_device *ec_dev = to_ec_dev(dev);

        return cros_ec_suspend(ec_dev);
}

static int cros_ec_i2c_resume(struct device *dev)
{
        struct cros_ec_device *ec_dev = to_ec_dev(dev);

        return cros_ec_resume(ec_dev);
}
#endif

static const struct dev_pm_ops cros_ec_i2c_pm_ops = {
        SET_LATE_SYSTEM_SLEEP_PM_OPS(cros_ec_i2c_suspend, cros_ec_i2c_resume)
};

#ifdef CONFIG_OF
static const struct of_device_id cros_ec_i2c_of_match[] = {
        { .compatible = "google,cros-ec-i2c", },
        { /* sentinel */ },
};
MODULE_DEVICE_TABLE(of, cros_ec_i2c_of_match);
#endif

static const struct i2c_device_id cros_ec_i2c_id[] = {
        { "cros-ec-i2c" },
        { }
};
MODULE_DEVICE_TABLE(i2c, cros_ec_i2c_id);

#ifdef CONFIG_ACPI
static const struct acpi_device_id cros_ec_i2c_acpi_id[] = {
        { "GOOG0008", 0 },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(acpi, cros_ec_i2c_acpi_id);
#endif

static struct i2c_driver cros_ec_driver = {
        .driver = {
                .name   = "cros-ec-i2c",
                .acpi_match_table = ACPI_PTR(cros_ec_i2c_acpi_id),
                .of_match_table = of_match_ptr(cros_ec_i2c_of_match),
                .pm     = &cros_ec_i2c_pm_ops,
        },
        .probe          = cros_ec_i2c_probe,
        .remove         = cros_ec_i2c_remove,
        .id_table       = cros_ec_i2c_id,
};

module_i2c_driver(cros_ec_driver);

MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("I2C interface for ChromeOS Embedded Controller");