/*
 * cros_ec_lpc - LPC access to the Chrome OS Embedded Controller
 *
 * Copyright (C) 2012-2015 Google, Inc
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * This driver uses the Chrome OS EC byte-level message-based protocol for
 * communicating the keyboard state (which keys are pressed) from a keyboard EC
 * to the AP over some bus (such as i2c, lpc, spi).  The EC does debouncing,
 * but everything else (including deghosting) is done here.  The main
 * motivation for this is to keep the EC firmware as simple as possible, since
 * it cannot be easily upgraded and EC flash/IRAM space is relatively
 * expensive.
 */

#include <linux/acpi.h>
#include <linux/dmi.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/mfd/cros_ec.h>
#include <linux/mfd/cros_ec_commands.h>
#include <linux/mfd/cros_ec_lpc_reg.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/printk.h>

#define DRV_NAME "cros_ec_lpcs"
#define ACPI_DRV_NAME "GOOG0004"

static int ec_response_timed_out(void)
{
        unsigned long one_second = jiffies + HZ;
        u8 data;

        usleep_range(200, 300);
        do {
                if (!(cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_CMD, 1, &data) &
                    EC_LPC_STATUS_BUSY_MASK))
                        return 0;
                usleep_range(100, 200);
        } while (time_before(jiffies, one_second));

        return 1;
}

static int cros_ec_pkt_xfer_lpc(struct cros_ec_device *ec,
                                struct cros_ec_command *msg)
{
        struct ec_host_request *request;
        struct ec_host_response response;
        u8 sum;
        int ret = 0;
        u8 *dout;

        ret = cros_ec_prepare_tx(ec, msg);

        /* Write buffer */
        cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_PACKET, ret, ec->dout);

        request = (struct ec_host_request *)ec->dout;

        /* Here we go */
        sum = EC_COMMAND_PROTOCOL_3;
        cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_CMD, 1, &sum);

        if (ec_response_timed_out()) {
                dev_warn(ec->dev, "EC responsed timed out\n");
                ret = -EIO;
                goto done;
        }

        /* Check result */
        msg->result = cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_DATA, 1, &sum);
        ret = cros_ec_check_result(ec, msg);
        if (ret)
                goto done;

        /* Read back response */
        dout = (u8 *)&response;
        sum = cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_PACKET, sizeof(response),
                                     dout);

        msg->result = response.result;

        if (response.data_len > msg->insize) {
                dev_err(ec->dev,
                        "packet too long (%d bytes, expected %d)",
                        response.data_len, msg->insize);
                ret = -EMSGSIZE;
                goto done;
        }

        /* Read response and process checksum */
        sum += cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_PACKET +
                                      sizeof(response), response.data_len,
                                      msg->data);

        if (sum) {
                dev_err(ec->dev,
                        "bad packet checksum %02x\n",
                        response.checksum);
                ret = -EBADMSG;
                goto done;
        }

        /* Return actual amount of data received */
        ret = response.data_len;
done:
        return ret;
}

static int cros_ec_cmd_xfer_lpc(struct cros_ec_device *ec,
                                struct cros_ec_command *msg)
{
        struct ec_lpc_host_args args;
        u8 sum;
        int ret = 0;

        if (msg->outsize > EC_PROTO2_MAX_PARAM_SIZE ||
            msg->insize > EC_PROTO2_MAX_PARAM_SIZE) {
                dev_err(ec->dev,
                        "invalid buffer sizes (out %d, in %d)\n",
                        msg->outsize, msg->insize);
                return -EINVAL;
        }

        /* Now actually send the command to the EC and get the result */
        args.flags = EC_HOST_ARGS_FLAG_FROM_HOST;
        args.command_version = msg->version;
        args.data_size = msg->outsize;

        /* Initialize checksum */
        sum = msg->command + args.flags + args.command_version + args.data_size;

        /* Copy data and update checksum */
        sum += cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_PARAM, msg->outsize,
                                       msg->data);

        /* Finalize checksum and write args */
        args.checksum = sum;
        cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_ARGS, sizeof(args),
                                (u8 *)&args);

        /* Here we go */
        sum = msg->command;
        cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_CMD, 1, &sum);

        if (ec_response_timed_out()) {
                dev_warn(ec->dev, "EC responsed timed out\n");
                ret = -EIO;
                goto done;
        }

        /* Check result */
        msg->result = cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_DATA, 1, &sum);
        ret = cros_ec_check_result(ec, msg);
        if (ret)
                goto done;

        /* Read back args */
        cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_ARGS, sizeof(args),
                               (u8 *)&args);

        if (args.data_size > msg->insize) {
                dev_err(ec->dev,
                        "packet too long (%d bytes, expected %d)",
                        args.data_size, msg->insize);
                ret = -ENOSPC;
                goto done;
        }

        /* Start calculating response checksum */
        sum = msg->command + args.flags + args.command_version + args.data_size;

        /* Read response and update checksum */
        sum += cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_PARAM, args.data_size,
                                      msg->data);

        /* Verify checksum */
        if (args.checksum != sum) {
                dev_err(ec->dev,
                        "bad packet checksum, expected %02x, got %02x\n",
                        args.checksum, sum);
                ret = -EBADMSG;
                goto done;
        }

        /* Return actual amount of data received */
        ret = args.data_size;
done:
        return ret;
}

/* Returns num bytes read, or negative on error. Doesn't need locking. */
static int cros_ec_lpc_readmem(struct cros_ec_device *ec, unsigned int offset,
                               unsigned int bytes, void *dest)
{
        int i = offset;
        char *s = dest;
        int cnt = 0;

        if (offset >= EC_MEMMAP_SIZE - bytes)
                return -EINVAL;

        /* fixed length */
        if (bytes) {
                cros_ec_lpc_read_bytes(EC_LPC_ADDR_MEMMAP + offset, bytes, s);
                return bytes;
        }

        /* string */
        for (; i < EC_MEMMAP_SIZE; i++, s++) {
                cros_ec_lpc_read_bytes(EC_LPC_ADDR_MEMMAP + i, 1, s);
                cnt++;
                if (!*s)
                        break;
        }

        return cnt;
}

static void cros_ec_lpc_acpi_notify(acpi_handle device, u32 value, void *data)
{
        struct cros_ec_device *ec_dev = data;

        if (ec_dev->mkbp_event_supported &&
            cros_ec_get_next_event(ec_dev, NULL) > 0)
                blocking_notifier_call_chain(&ec_dev->event_notifier, 0,
                                             ec_dev);
}

static int cros_ec_lpc_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct acpi_device *adev;
        acpi_status status;
        struct cros_ec_device *ec_dev;
        u8 buf[2];
        int ret;

        if (!devm_request_region(dev, EC_LPC_ADDR_MEMMAP, EC_MEMMAP_SIZE,
                                 dev_name(dev))) {
                dev_err(dev, "couldn't reserve memmap region\n");
                return -EBUSY;
        }

        cros_ec_lpc_read_bytes(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID, 2, buf);
        if (buf[0] != 'E' || buf[1] != 'C') {
                dev_err(dev, "EC ID not detected\n");
                return -ENODEV;
        }

        if (!devm_request_region(dev, EC_HOST_CMD_REGION0,
                                 EC_HOST_CMD_REGION_SIZE, dev_name(dev))) {
                dev_err(dev, "couldn't reserve region0\n");
                return -EBUSY;
        }
        if (!devm_request_region(dev, EC_HOST_CMD_REGION1,
                                 EC_HOST_CMD_REGION_SIZE, dev_name(dev))) {
                dev_err(dev, "couldn't reserve region1\n");
                return -EBUSY;
        }

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

        platform_set_drvdata(pdev, ec_dev);
        ec_dev->dev = dev;
        ec_dev->phys_name = dev_name(dev);
        ec_dev->cmd_xfer = cros_ec_cmd_xfer_lpc;
        ec_dev->pkt_xfer = cros_ec_pkt_xfer_lpc;
        ec_dev->cmd_readmem = cros_ec_lpc_readmem;
        ec_dev->din_size = sizeof(struct ec_host_response) +
                           sizeof(struct ec_response_get_protocol_info);
        ec_dev->dout_size = sizeof(struct ec_host_request);

        ret = cros_ec_register(ec_dev);
        if (ret) {
                dev_err(dev, "couldn't register ec_dev (%d)\n", ret);
                return ret;
        }

        /*
         * Connect a notify handler to process MKBP messages if we have a
         * companion ACPI device.
         */
        adev = ACPI_COMPANION(dev);
        if (adev) {
                status = acpi_install_notify_handler(adev->handle,
                                                     ACPI_ALL_NOTIFY,
                                                     cros_ec_lpc_acpi_notify,
                                                     ec_dev);
                if (ACPI_FAILURE(status))
                        dev_warn(dev, "Failed to register notifier %08x\n",
                                 status);
        }

        return 0;
}

static int cros_ec_lpc_remove(struct platform_device *pdev)
{
        struct cros_ec_device *ec_dev;
        struct acpi_device *adev;

        adev = ACPI_COMPANION(&pdev->dev);
        if (adev)
                acpi_remove_notify_handler(adev->handle, ACPI_ALL_NOTIFY,
                                           cros_ec_lpc_acpi_notify);

        ec_dev = platform_get_drvdata(pdev);
        cros_ec_remove(ec_dev);

        return 0;
}

static const struct acpi_device_id cros_ec_lpc_acpi_device_ids[] = {
        { ACPI_DRV_NAME, 0 },
        { }
};
MODULE_DEVICE_TABLE(acpi, cros_ec_lpc_acpi_device_ids);

static const struct dmi_system_id cros_ec_lpc_dmi_table[] __initconst = {
        {
                /*
                 * Today all Chromebooks/boxes ship with Google_* as version and
                 * coreboot as bios vendor. No other systems with this
                 * combination are known to date.
                 */
                .matches = {
                        DMI_MATCH(DMI_BIOS_VENDOR, "coreboot"),
                        DMI_MATCH(DMI_BIOS_VERSION, "Google_"),
                },
        },
        {
                /* x86-link, the Chromebook Pixel. */
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
                        DMI_MATCH(DMI_PRODUCT_NAME, "Link"),
                },
        },
        {
                /* x86-samus, the Chromebook Pixel 2. */
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
                        DMI_MATCH(DMI_PRODUCT_NAME, "Samus"),
                },
        },
        {
                /* x86-peppy, the Acer C720 Chromebook. */
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
                        DMI_MATCH(DMI_PRODUCT_NAME, "Peppy"),
                },
        },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(dmi, cros_ec_lpc_dmi_table);

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

        return cros_ec_suspend(ec_dev);
}

static int cros_ec_lpc_resume(struct device *dev)
{
        struct cros_ec_device *ec_dev = dev_get_drvdata(dev);

        return cros_ec_resume(ec_dev);
}
#endif

const struct dev_pm_ops cros_ec_lpc_pm_ops = {
        SET_LATE_SYSTEM_SLEEP_PM_OPS(cros_ec_lpc_suspend, cros_ec_lpc_resume)
};

static struct platform_driver cros_ec_lpc_driver = {
        .driver = {
                .name = DRV_NAME,
                .acpi_match_table = cros_ec_lpc_acpi_device_ids,
                .pm = &cros_ec_lpc_pm_ops,
        },
        .probe = cros_ec_lpc_probe,
        .remove = cros_ec_lpc_remove,
};

static int __init cros_ec_lpc_init(void)
{
        int ret;

        if (!dmi_check_system(cros_ec_lpc_dmi_table)) {
                pr_err(DRV_NAME ": unsupported system.\n");
                return -ENODEV;
        }

        cros_ec_lpc_reg_init();

        /* Register the driver */
        ret = platform_driver_register(&cros_ec_lpc_driver);
        if (ret) {
                pr_err(DRV_NAME ": can't register driver: %d\n", ret);
                cros_ec_lpc_reg_destroy();
                return ret;
        }

        return 0;
}

static void __exit cros_ec_lpc_exit(void)
{
        platform_driver_unregister(&cros_ec_lpc_driver);
        cros_ec_lpc_reg_destroy();
}

module_init(cros_ec_lpc_init);
module_exit(cros_ec_lpc_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("ChromeOS EC LPC driver");