/*
 * Chromium OS cros_ec driver - LPC interface
 *
 * Copyright (c) 2012 The Chromium OS Authors.
 *
 * SPDX-License-Identifier:     GPL-2.0+
 */

/*
 * The Matrix Keyboard Protocol driver handles talking to the keyboard
 * controller chip. Mostly this is for keyboard functions, but some other
 * things have slipped in, so we provide generic services to talk to the
 * KBC.
 */

#include <common.h>
#include <dm.h>
#include <command.h>
#include <cros_ec.h>
#include <asm/io.h>

#ifdef DEBUG_TRACE
#define debug_trace(fmt, b...)  debug(fmt, ##b)
#else
#define debug_trace(fmt, b...)
#endif

static int wait_for_sync(struct cros_ec_dev *dev)
{
        unsigned long start;

        start = get_timer(0);
        while (inb(EC_LPC_ADDR_HOST_CMD) & EC_LPC_STATUS_BUSY_MASK) {
                if (get_timer(start) > 1000) {
                        debug("%s: Timeout waiting for CROS_EC sync\n",
                              __func__);
                        return -1;
                }
        }

        return 0;
}

int cros_ec_lpc_command(struct udevice *udev, uint8_t cmd, int cmd_version,
                     const uint8_t *dout, int dout_len,
                     uint8_t **dinp, int din_len)
{
        struct cros_ec_dev *dev = dev_get_uclass_priv(udev);
        const int cmd_addr = EC_LPC_ADDR_HOST_CMD;
        const int data_addr = EC_LPC_ADDR_HOST_DATA;
        const int args_addr = EC_LPC_ADDR_HOST_ARGS;
        const int param_addr = EC_LPC_ADDR_HOST_PARAM;

        struct ec_lpc_host_args args;
        uint8_t *d;
        int csum;
        int i;

        if (dout_len > EC_PROTO2_MAX_PARAM_SIZE) {
                debug("%s: Cannot send %d bytes\n", __func__, dout_len);
                return -1;
        }

        /* Fill in args */
        args.flags = EC_HOST_ARGS_FLAG_FROM_HOST;
        args.command_version = cmd_version;
        args.data_size = dout_len;

        /* Calculate checksum */
        csum = cmd + args.flags + args.command_version + args.data_size;
        for (i = 0, d = (uint8_t *)dout; i < dout_len; i++, d++)
                csum += *d;

        args.checksum = (uint8_t)csum;

        if (wait_for_sync(dev)) {
                debug("%s: Timeout waiting ready\n", __func__);
                return -1;
        }

        /* Write args */
        for (i = 0, d = (uint8_t *)&args; i < sizeof(args); i++, d++)
                outb(*d, args_addr + i);

        /* Write data, if any */
        debug_trace("cmd: %02x, ver: %02x", cmd, cmd_version);
        for (i = 0, d = (uint8_t *)dout; i < dout_len; i++, d++) {
                outb(*d, param_addr + i);
                debug_trace("%02x ", *d);
        }

        outb(cmd, cmd_addr);
        debug_trace("\n");

        if (wait_for_sync(dev)) {
                debug("%s: Timeout waiting for response\n", __func__);
                return -1;
        }

        /* Check result */
        i = inb(data_addr);
        if (i) {
                debug("%s: CROS_EC result code %d\n", __func__, i);
                return -i;
        }

        /* Read back args */
        for (i = 0, d = (uint8_t *)&args; i < sizeof(args); i++, d++)
                *d = inb(args_addr + i);

        /*
         * If EC didn't modify args flags, then somehow we sent a new-style
         * command to an old EC, which means it would have read its params
         * from the wrong place.
         */
        if (!(args.flags & EC_HOST_ARGS_FLAG_TO_HOST)) {
                debug("%s: CROS_EC protocol mismatch\n", __func__);
                return -EC_RES_INVALID_RESPONSE;
        }

        if (args.data_size > din_len) {
                debug("%s: CROS_EC returned too much data %d > %d\n",
                      __func__, args.data_size, din_len);
                return -EC_RES_INVALID_RESPONSE;
        }

        /* Read data, if any */
        for (i = 0, d = (uint8_t *)dev->din; i < args.data_size; i++, d++) {
                *d = inb(param_addr + i);
                debug_trace("%02x ", *d);
        }
        debug_trace("\n");

        /* Verify checksum */
        csum = cmd + args.flags + args.command_version + args.data_size;
        for (i = 0, d = (uint8_t *)dev->din; i < args.data_size; i++, d++)
                csum += *d;

        if (args.checksum != (uint8_t)csum) {
                debug("%s: CROS_EC response has invalid checksum\n", __func__);
                return -EC_RES_INVALID_CHECKSUM;
        }
        *dinp = dev->din;

        /* Return actual amount of data received */
        return args.data_size;
}

/**
 * Initialize LPC protocol.
 *
 * @param dev           CROS_EC device
 * @param blob          Device tree blob
 * @return 0 if ok, -1 on error
 */
int cros_ec_lpc_init(struct cros_ec_dev *dev, const void *blob)
{
        int byte, i;

        /* See if we can find an EC at the other end */
        byte = 0xff;
        byte &= inb(EC_LPC_ADDR_HOST_CMD);
        byte &= inb(EC_LPC_ADDR_HOST_DATA);
        for (i = 0; i < EC_PROTO2_MAX_PARAM_SIZE && (byte == 0xff); i++)
                byte &= inb(EC_LPC_ADDR_HOST_PARAM + i);
        if (byte == 0xff) {
                debug("%s: CROS_EC device not found on LPC bus\n",
                        __func__);
                return -1;
        }

        return 0;
}

/*
 * Test if LPC command args are supported.
 *
 * The cheapest way to do this is by looking for the memory-mapped
 * flag.  This is faster than sending a new-style 'hello' command and
 * seeing whether the EC sets the EC_HOST_ARGS_FLAG_FROM_HOST flag
 * in args when it responds.
 */
static int cros_ec_lpc_check_version(struct udevice *dev)
{
        if (inb(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID) == 'E' &&
                        inb(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID + 1)
                                == 'C' &&
                        (inb(EC_LPC_ADDR_MEMMAP +
                                EC_MEMMAP_HOST_CMD_FLAGS) &
                                EC_HOST_CMD_FLAG_LPC_ARGS_SUPPORTED)) {
                return 0;
        }

        printf("%s: ERROR: old EC interface not supported\n", __func__);
        return -1;
}

static int cros_ec_probe(struct udevice *dev)
{
        return cros_ec_register(dev);
}

static struct dm_cros_ec_ops cros_ec_ops = {
        .command = cros_ec_lpc_command,
        .check_version = cros_ec_lpc_check_version,
};

static const struct udevice_id cros_ec_ids[] = {
        { .compatible = "google,cros-ec-lpc" },
        { }
};

U_BOOT_DRIVER(cros_ec_lpc) = {
        .name           = "cros_ec_lpc",
        .id             = UCLASS_CROS_EC,
        .of_match       = cros_ec_ids,
        .probe          = cros_ec_probe,
        .ops            = &cros_ec_ops,
};