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

/*
 * This is the interface to the Chrome OS EC. It provides keyboard functions,
 * power control and battery management. Quite a few other functions are
 * provided to enable the EC software to be updated, talk to the EC's I2C bus
 * and store a small amount of data in a memory which persists while the EC
 * is not reset.
 */

#include <common.h>
#include <command.h>
#include <dm.h>
#include <i2c.h>
#include <cros_ec.h>
#include <fdtdec.h>
#include <malloc.h>
#include <spi.h>
#include <linux/errno.h>
#include <asm/io.h>
#include <asm-generic/gpio.h>
#include <dm/device-internal.h>
#include <dm/of_extra.h>
#include <dm/uclass-internal.h>

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

enum {
        /* Timeout waiting for a flash erase command to complete */
        CROS_EC_CMD_TIMEOUT_MS  = 5000,
        /* Timeout waiting for a synchronous hash to be recomputed */
        CROS_EC_CMD_HASH_TIMEOUT_MS = 2000,
};

DECLARE_GLOBAL_DATA_PTR;

void cros_ec_dump_data(const char *name, int cmd, const uint8_t *data, int len)
{
#ifdef DEBUG
        int i;

        printf("%s: ", name);
        if (cmd != -1)
                printf("cmd=%#x: ", cmd);
        for (i = 0; i < len; i++)
                printf("%02x ", data[i]);
        printf("\n");
#endif
}

/*
 * Calculate a simple 8-bit checksum of a data block
 *
 * @param data  Data block to checksum
 * @param size  Size of data block in bytes
 * @return checksum value (0 to 255)
 */
int cros_ec_calc_checksum(const uint8_t *data, int size)
{
        int csum, i;

        for (i = csum = 0; i < size; i++)
                csum += data[i];
        return csum & 0xff;
}

/**
 * Create a request packet for protocol version 3.
 *
 * The packet is stored in the device's internal output buffer.
 *
 * @param dev           CROS-EC device
 * @param cmd           Command to send (EC_CMD_...)
 * @param cmd_version   Version of command to send (EC_VER_...)
 * @param dout          Output data (may be NULL If dout_len=0)
 * @param dout_len      Size of output data in bytes
 * @return packet size in bytes, or <0 if error.
 */
static int create_proto3_request(struct cros_ec_dev *dev,
                                 int cmd, int cmd_version,
                                 const void *dout, int dout_len)
{
        struct ec_host_request *rq = (struct ec_host_request *)dev->dout;
        int out_bytes = dout_len + sizeof(*rq);

        /* Fail if output size is too big */
        if (out_bytes > (int)sizeof(dev->dout)) {
                debug("%s: Cannot send %d bytes\n", __func__, dout_len);
                return -EC_RES_REQUEST_TRUNCATED;
        }

        /* Fill in request packet */
        rq->struct_version = EC_HOST_REQUEST_VERSION;
        rq->checksum = 0;
        rq->command = cmd;
        rq->command_version = cmd_version;
        rq->reserved = 0;
        rq->data_len = dout_len;

        /* Copy data after header */
        memcpy(rq + 1, dout, dout_len);

        /* Write checksum field so the entire packet sums to 0 */
        rq->checksum = (uint8_t)(-cros_ec_calc_checksum(dev->dout, out_bytes));

        cros_ec_dump_data("out", cmd, dev->dout, out_bytes);

        /* Return size of request packet */
        return out_bytes;
}

/**
 * Prepare the device to receive a protocol version 3 response.
 *
 * @param dev           CROS-EC device
 * @param din_len       Maximum size of response in bytes
 * @return maximum expected number of bytes in response, or <0 if error.
 */
static int prepare_proto3_response_buffer(struct cros_ec_dev *dev, int din_len)
{
        int in_bytes = din_len + sizeof(struct ec_host_response);

        /* Fail if input size is too big */
        if (in_bytes > (int)sizeof(dev->din)) {
                debug("%s: Cannot receive %d bytes\n", __func__, din_len);
                return -EC_RES_RESPONSE_TOO_BIG;
        }

        /* Return expected size of response packet */
        return in_bytes;
}

/**
 * Handle a protocol version 3 response packet.
 *
 * The packet must already be stored in the device's internal input buffer.
 *
 * @param dev           CROS-EC device
 * @param dinp          Returns pointer to response data
 * @param din_len       Maximum size of response in bytes
 * @return number of bytes of response data, or <0 if error. Note that error
 * codes can be from errno.h or -ve EC_RES_INVALID_CHECKSUM values (and they
 * overlap!)
 */
static int handle_proto3_response(struct cros_ec_dev *dev,
                                  uint8_t **dinp, int din_len)
{
        struct ec_host_response *rs = (struct ec_host_response *)dev->din;
        int in_bytes;
        int csum;

        cros_ec_dump_data("in-header", -1, dev->din, sizeof(*rs));

        /* Check input data */
        if (rs->struct_version != EC_HOST_RESPONSE_VERSION) {
                debug("%s: EC response version mismatch\n", __func__);
                return -EC_RES_INVALID_RESPONSE;
        }

        if (rs->reserved) {
                debug("%s: EC response reserved != 0\n", __func__);
                return -EC_RES_INVALID_RESPONSE;
        }

        if (rs->data_len > din_len) {
                debug("%s: EC returned too much data\n", __func__);
                return -EC_RES_RESPONSE_TOO_BIG;
        }

        cros_ec_dump_data("in-data", -1, dev->din + sizeof(*rs), rs->data_len);

        /* Update in_bytes to actual data size */
        in_bytes = sizeof(*rs) + rs->data_len;

        /* Verify checksum */
        csum = cros_ec_calc_checksum(dev->din, in_bytes);
        if (csum) {
                debug("%s: EC response checksum invalid: 0x%02x\n", __func__,
                      csum);
                return -EC_RES_INVALID_CHECKSUM;
        }

        /* Return error result, if any */
        if (rs->result)
                return -(int)rs->result;

        /* If we're still here, set response data pointer and return length */
        *dinp = (uint8_t *)(rs + 1);

        return rs->data_len;
}

static int send_command_proto3(struct cros_ec_dev *dev,
                               int cmd, int cmd_version,
                               const void *dout, int dout_len,
                               uint8_t **dinp, int din_len)
{
        struct dm_cros_ec_ops *ops;
        int out_bytes, in_bytes;
        int rv;

        /* Create request packet */
        out_bytes = create_proto3_request(dev, cmd, cmd_version,
                                          dout, dout_len);
        if (out_bytes < 0)
                return out_bytes;

        /* Prepare response buffer */
        in_bytes = prepare_proto3_response_buffer(dev, din_len);
        if (in_bytes < 0)
                return in_bytes;

        ops = dm_cros_ec_get_ops(dev->dev);
        rv = ops->packet ? ops->packet(dev->dev, out_bytes, in_bytes) : -ENOSYS;
        if (rv < 0)
                return rv;

        /* Process the response */
        return handle_proto3_response(dev, dinp, din_len);
}

static int send_command(struct cros_ec_dev *dev, uint8_t cmd, int cmd_version,
                        const void *dout, int dout_len,
                        uint8_t **dinp, int din_len)
{
        struct dm_cros_ec_ops *ops;
        int ret = -1;

        /* Handle protocol version 3 support */
        if (dev->protocol_version == 3) {
                return send_command_proto3(dev, cmd, cmd_version,
                                           dout, dout_len, dinp, din_len);
        }

        ops = dm_cros_ec_get_ops(dev->dev);
        ret = ops->command(dev->dev, cmd, cmd_version,
                           (const uint8_t *)dout, dout_len, dinp, din_len);

        return ret;
}

/**
 * Send a command to the CROS-EC device and return the reply.
 *
 * The device's internal input/output buffers are used.
 *
 * @param dev           CROS-EC device
 * @param cmd           Command to send (EC_CMD_...)
 * @param cmd_version   Version of command to send (EC_VER_...)
 * @param dout          Output data (may be NULL If dout_len=0)
 * @param dout_len      Size of output data in bytes
 * @param dinp          Response data (may be NULL If din_len=0).
 *                      If not NULL, it will be updated to point to the data
 *                      and will always be double word aligned (64-bits)
 * @param din_len       Maximum size of response in bytes
 * @return number of bytes in response, or -ve on error
 */
static int ec_command_inptr(struct cros_ec_dev *dev, uint8_t cmd,
                int cmd_version, const void *dout, int dout_len, uint8_t **dinp,
                int din_len)
{
        uint8_t *din = NULL;
        int len;

        len = send_command(dev, cmd, cmd_version, dout, dout_len,
                                &din, din_len);

        /* If the command doesn't complete, wait a while */
        if (len == -EC_RES_IN_PROGRESS) {
                struct ec_response_get_comms_status *resp = NULL;
                ulong start;

                /* Wait for command to complete */
                start = get_timer(0);
                do {
                        int ret;

                        mdelay(50);     /* Insert some reasonable delay */
                        ret = send_command(dev, EC_CMD_GET_COMMS_STATUS, 0,
                                        NULL, 0,
                                        (uint8_t **)&resp, sizeof(*resp));
                        if (ret < 0)
                                return ret;

                        if (get_timer(start) > CROS_EC_CMD_TIMEOUT_MS) {
                                debug("%s: Command %#02x timeout\n",
                                      __func__, cmd);
                                return -EC_RES_TIMEOUT;
                        }
                } while (resp->flags & EC_COMMS_STATUS_PROCESSING);

                /* OK it completed, so read the status response */
                /* not sure why it was 0 for the last argument */
                len = send_command(dev, EC_CMD_RESEND_RESPONSE, 0,
                                NULL, 0, &din, din_len);
        }

        debug("%s: len=%d, din=%p\n", __func__, len, din);
        if (dinp) {
                /* If we have any data to return, it must be 64bit-aligned */
                assert(len <= 0 || !((uintptr_t)din & 7));
                *dinp = din;
        }

        return len;
}

/**
 * Send a command to the CROS-EC device and return the reply.
 *
 * The device's internal input/output buffers are used.
 *
 * @param dev           CROS-EC device
 * @param cmd           Command to send (EC_CMD_...)
 * @param cmd_version   Version of command to send (EC_VER_...)
 * @param dout          Output data (may be NULL If dout_len=0)
 * @param dout_len      Size of output data in bytes
 * @param din           Response data (may be NULL If din_len=0).
 *                      It not NULL, it is a place for ec_command() to copy the
 *      data to.
 * @param din_len       Maximum size of response in bytes
 * @return number of bytes in response, or -ve on error
 */
static int ec_command(struct cros_ec_dev *dev, uint8_t cmd, int cmd_version,
                      const void *dout, int dout_len,
                      void *din, int din_len)
{
        uint8_t *in_buffer;
        int len;

        assert((din_len == 0) || din);
        len = ec_command_inptr(dev, cmd, cmd_version, dout, dout_len,
                        &in_buffer, din_len);
        if (len > 0) {
                /*
                 * If we were asked to put it somewhere, do so, otherwise just
                 * disregard the result.
                 */
                if (din && in_buffer) {
                        assert(len <= din_len);
                        memmove(din, in_buffer, len);
                }
        }
        return len;
}

int cros_ec_scan_keyboard(struct udevice *dev, struct mbkp_keyscan *scan)
{
        struct cros_ec_dev *cdev = dev_get_uclass_priv(dev);

        if (ec_command(cdev, EC_CMD_MKBP_STATE, 0, NULL, 0, scan,
                       sizeof(scan->data)) != sizeof(scan->data))
                return -1;

        return 0;
}

int cros_ec_read_id(struct cros_ec_dev *dev, char *id, int maxlen)
{
        struct ec_response_get_version *r;

        if (ec_command_inptr(dev, EC_CMD_GET_VERSION, 0, NULL, 0,
                        (uint8_t **)&r, sizeof(*r)) != sizeof(*r))
                return -1;

        if (maxlen > (int)sizeof(r->version_string_ro))
                maxlen = sizeof(r->version_string_ro);

        switch (r->current_image) {
        case EC_IMAGE_RO:
                memcpy(id, r->version_string_ro, maxlen);
                break;
        case EC_IMAGE_RW:
                memcpy(id, r->version_string_rw, maxlen);
                break;
        default:
                return -1;
        }

        id[maxlen - 1] = '\0';
        return 0;
}

int cros_ec_read_version(struct cros_ec_dev *dev,
                       struct ec_response_get_version **versionp)
{
        if (ec_command_inptr(dev, EC_CMD_GET_VERSION, 0, NULL, 0,
                        (uint8_t **)versionp, sizeof(**versionp))
                        != sizeof(**versionp))
                return -1;

        return 0;
}

int cros_ec_read_build_info(struct cros_ec_dev *dev, char **strp)
{
        if (ec_command_inptr(dev, EC_CMD_GET_BUILD_INFO, 0, NULL, 0,
                        (uint8_t **)strp, EC_PROTO2_MAX_PARAM_SIZE) < 0)
                return -1;

        return 0;
}

int cros_ec_read_current_image(struct cros_ec_dev *dev,
                enum ec_current_image *image)
{
        struct ec_response_get_version *r;

        if (ec_command_inptr(dev, EC_CMD_GET_VERSION, 0, NULL, 0,
                        (uint8_t **)&r, sizeof(*r)) != sizeof(*r))
                return -1;

        *image = r->current_image;
        return 0;
}

static int cros_ec_wait_on_hash_done(struct cros_ec_dev *dev,
                                  struct ec_response_vboot_hash *hash)
{
        struct ec_params_vboot_hash p;
        ulong start;

        start = get_timer(0);
        while (hash->status == EC_VBOOT_HASH_STATUS_BUSY) {
                mdelay(50);     /* Insert some reasonable delay */

                p.cmd = EC_VBOOT_HASH_GET;
                if (ec_command(dev, EC_CMD_VBOOT_HASH, 0, &p, sizeof(p),
                       hash, sizeof(*hash)) < 0)
                        return -1;

                if (get_timer(start) > CROS_EC_CMD_HASH_TIMEOUT_MS) {
                        debug("%s: EC_VBOOT_HASH_GET timeout\n", __func__);
                        return -EC_RES_TIMEOUT;
                }
        }
        return 0;
}


int cros_ec_read_hash(struct cros_ec_dev *dev,
                struct ec_response_vboot_hash *hash)
{
        struct ec_params_vboot_hash p;
        int rv;

        p.cmd = EC_VBOOT_HASH_GET;
        if (ec_command(dev, EC_CMD_VBOOT_HASH, 0, &p, sizeof(p),
                       hash, sizeof(*hash)) < 0)
                return -1;

        /* If the EC is busy calculating the hash, fidget until it's done. */
        rv = cros_ec_wait_on_hash_done(dev, hash);
        if (rv)
                return rv;

        /* If the hash is valid, we're done. Otherwise, we have to kick it off
         * again and wait for it to complete. Note that we explicitly assume
         * that hashing zero bytes is always wrong, even though that would
         * produce a valid hash value. */
        if (hash->status == EC_VBOOT_HASH_STATUS_DONE && hash->size)
                return 0;

        debug("%s: No valid hash (status=%d size=%d). Compute one...\n",
              __func__, hash->status, hash->size);

        p.cmd = EC_VBOOT_HASH_START;
        p.hash_type = EC_VBOOT_HASH_TYPE_SHA256;
        p.nonce_size = 0;
        p.offset = EC_VBOOT_HASH_OFFSET_RW;

        if (ec_command(dev, EC_CMD_VBOOT_HASH, 0, &p, sizeof(p),
                       hash, sizeof(*hash)) < 0)
                return -1;

        rv = cros_ec_wait_on_hash_done(dev, hash);
        if (rv)
                return rv;

        debug("%s: hash done\n", __func__);

        return 0;
}

static int cros_ec_invalidate_hash(struct cros_ec_dev *dev)
{
        struct ec_params_vboot_hash p;
        struct ec_response_vboot_hash *hash;

        /* We don't have an explict command for the EC to discard its current
         * hash value, so we'll just tell it to calculate one that we know is
         * wrong (we claim that hashing zero bytes is always invalid).
         */
        p.cmd = EC_VBOOT_HASH_RECALC;
        p.hash_type = EC_VBOOT_HASH_TYPE_SHA256;
        p.nonce_size = 0;
        p.offset = 0;
        p.size = 0;

        debug("%s:\n", __func__);

        if (ec_command_inptr(dev, EC_CMD_VBOOT_HASH, 0, &p, sizeof(p),
                       (uint8_t **)&hash, sizeof(*hash)) < 0)
                return -1;

        /* No need to wait for it to finish */
        return 0;
}

int cros_ec_reboot(struct cros_ec_dev *dev, enum ec_reboot_cmd cmd,
                uint8_t flags)
{
        struct ec_params_reboot_ec p;

        p.cmd = cmd;
        p.flags = flags;

        if (ec_command_inptr(dev, EC_CMD_REBOOT_EC, 0, &p, sizeof(p), NULL, 0)
                        < 0)
                return -1;

        if (!(flags & EC_REBOOT_FLAG_ON_AP_SHUTDOWN)) {
                /*
                 * EC reboot will take place immediately so delay to allow it
                 * to complete.  Note that some reboot types (EC_REBOOT_COLD)
                 * will reboot the AP as well, in which case we won't actually
                 * get to this point.
                 */
                /*
                 * TODO(rspangler@chromium.org): Would be nice if we had a
                 * better way to determine when the reboot is complete.  Could
                 * we poll a memory-mapped LPC value?
                 */
                udelay(50000);
        }

        return 0;
}

int cros_ec_interrupt_pending(struct udevice *dev)
{
        struct cros_ec_dev *cdev = dev_get_uclass_priv(dev);

        /* no interrupt support : always poll */
        if (!dm_gpio_is_valid(&cdev->ec_int))
                return -ENOENT;

        return dm_gpio_get_value(&cdev->ec_int);
}

int cros_ec_info(struct cros_ec_dev *dev, struct ec_response_mkbp_info *info)
{
        if (ec_command(dev, EC_CMD_MKBP_INFO, 0, NULL, 0, info,
                       sizeof(*info)) != sizeof(*info))
                return -1;

        return 0;
}

int cros_ec_get_host_events(struct cros_ec_dev *dev, uint32_t *events_ptr)
{
        struct ec_response_host_event_mask *resp;

        /*
         * Use the B copy of the event flags, because the main copy is already
         * used by ACPI/SMI.
         */
        if (ec_command_inptr(dev, EC_CMD_HOST_EVENT_GET_B, 0, NULL, 0,
                       (uint8_t **)&resp, sizeof(*resp)) < (int)sizeof(*resp))
                return -1;

        if (resp->mask & EC_HOST_EVENT_MASK(EC_HOST_EVENT_INVALID))
                return -1;

        *events_ptr = resp->mask;
        return 0;
}

int cros_ec_clear_host_events(struct cros_ec_dev *dev, uint32_t events)
{
        struct ec_params_host_event_mask params;

        params.mask = events;

        /*
         * Use the B copy of the event flags, so it affects the data returned
         * by cros_ec_get_host_events().
         */
        if (ec_command_inptr(dev, EC_CMD_HOST_EVENT_CLEAR_B, 0,
                       &params, sizeof(params), NULL, 0) < 0)
                return -1;

        return 0;
}

int cros_ec_flash_protect(struct cros_ec_dev *dev,
                       uint32_t set_mask, uint32_t set_flags,
                       struct ec_response_flash_protect *resp)
{
        struct ec_params_flash_protect params;

        params.mask = set_mask;
        params.flags = set_flags;

        if (ec_command(dev, EC_CMD_FLASH_PROTECT, EC_VER_FLASH_PROTECT,
                       &params, sizeof(params),
                       resp, sizeof(*resp)) != sizeof(*resp))
                return -1;

        return 0;
}

static int cros_ec_check_version(struct cros_ec_dev *dev)
{
        struct ec_params_hello req;
        struct ec_response_hello *resp;

        struct dm_cros_ec_ops *ops;
        int ret;

        ops = dm_cros_ec_get_ops(dev->dev);
        if (ops->check_version) {
                ret = ops->check_version(dev->dev);
                if (ret)
                        return ret;
        }

        /*
         * TODO(sjg@chromium.org).
         * There is a strange oddity here with the EC. We could just ignore
         * the response, i.e. pass the last two parameters as NULL and 0.
         * In this case we won't read back very many bytes from the EC.
         * On the I2C bus the EC gets upset about this and will try to send
         * the bytes anyway. This means that we will have to wait for that
         * to complete before continuing with a new EC command.
         *
         * This problem is probably unique to the I2C bus.
         *
         * So for now, just read all the data anyway.
         */

        /* Try sending a version 3 packet */
        dev->protocol_version = 3;
        req.in_data = 0;
        if (ec_command_inptr(dev, EC_CMD_HELLO, 0, &req, sizeof(req),
                             (uint8_t **)&resp, sizeof(*resp)) > 0) {
                return 0;
        }

        /* Try sending a version 2 packet */
        dev->protocol_version = 2;
        if (ec_command_inptr(dev, EC_CMD_HELLO, 0, &req, sizeof(req),
                       (uint8_t **)&resp, sizeof(*resp)) > 0) {
                return 0;
        }

        /*
         * Fail if we're still here, since the EC doesn't understand any
         * protcol version we speak.  Version 1 interface without command
         * version is no longer supported, and we don't know about any new
         * protocol versions.
         */
        dev->protocol_version = 0;
        printf("%s: ERROR: old EC interface not supported\n", __func__);
        return -1;
}

int cros_ec_test(struct cros_ec_dev *dev)
{
        struct ec_params_hello req;
        struct ec_response_hello *resp;

        req.in_data = 0x12345678;
        if (ec_command_inptr(dev, EC_CMD_HELLO, 0, &req, sizeof(req),
                       (uint8_t **)&resp, sizeof(*resp)) < sizeof(*resp)) {
                printf("ec_command_inptr() returned error\n");
                return -1;
        }
        if (resp->out_data != req.in_data + 0x01020304) {
                printf("Received invalid handshake %x\n", resp->out_data);
                return -1;
        }

        return 0;
}

int cros_ec_flash_offset(struct cros_ec_dev *dev, enum ec_flash_region region,
                      uint32_t *offset, uint32_t *size)
{
        struct ec_params_flash_region_info p;
        struct ec_response_flash_region_info *r;
        int ret;

        p.region = region;
        ret = ec_command_inptr(dev, EC_CMD_FLASH_REGION_INFO,
                         EC_VER_FLASH_REGION_INFO,
                         &p, sizeof(p), (uint8_t **)&r, sizeof(*r));
        if (ret != sizeof(*r))
                return -1;

        if (offset)
                *offset = r->offset;
        if (size)
                *size = r->size;

        return 0;
}

int cros_ec_flash_erase(struct cros_ec_dev *dev, uint32_t offset, uint32_t size)
{
        struct ec_params_flash_erase p;

        p.offset = offset;
        p.size = size;
        return ec_command_inptr(dev, EC_CMD_FLASH_ERASE, 0, &p, sizeof(p),
                        NULL, 0);
}

/**
 * Write a single block to the flash
 *
 * Write a block of data to the EC flash. The size must not exceed the flash
 * write block size which you can obtain from cros_ec_flash_write_burst_size().
 *
 * The offset starts at 0. You can obtain the region information from
 * cros_ec_flash_offset() to find out where to write for a particular region.
 *
 * Attempting to write to the region where the EC is currently running from
 * will result in an error.
 *
 * @param dev           CROS-EC device
 * @param data          Pointer to data buffer to write
 * @param offset        Offset within flash to write to.
 * @param size          Number of bytes to write
 * @return 0 if ok, -1 on error
 */
static int cros_ec_flash_write_block(struct cros_ec_dev *dev,
                const uint8_t *data, uint32_t offset, uint32_t size)
{
        struct ec_params_flash_write *p;
        int ret;

        p = malloc(sizeof(*p) + size);
        if (!p)
                return -ENOMEM;

        p->offset = offset;
        p->size = size;
        assert(data && p->size <= EC_FLASH_WRITE_VER0_SIZE);
        memcpy(p + 1, data, p->size);

        ret = ec_command_inptr(dev, EC_CMD_FLASH_WRITE, 0,
                          p, sizeof(*p) + size, NULL, 0) >= 0 ? 0 : -1;

        free(p);

        return ret;
}

/**
 * Return optimal flash write burst size
 */
static int cros_ec_flash_write_burst_size(struct cros_ec_dev *dev)
{
        return EC_FLASH_WRITE_VER0_SIZE;
}

/**
 * Check if a block of data is erased (all 0xff)
 *
 * This function is useful when dealing with flash, for checking whether a
 * data block is erased and thus does not need to be programmed.
 *
 * @param data          Pointer to data to check (must be word-aligned)
 * @param size          Number of bytes to check (must be word-aligned)
 * @return 0 if erased, non-zero if any word is not erased
 */
static int cros_ec_data_is_erased(const uint32_t *data, int size)
{
        assert(!(size & 3));
        size /= sizeof(uint32_t);
        for (; size > 0; size -= 4, data++)
                if (*data != -1U)
                        return 0;

        return 1;
}

/**
 * Read back flash parameters
 *
 * This function reads back parameters of the flash as reported by the EC
 *
 * @param dev  Pointer to device
 * @param info Pointer to output flash info struct
 */
int cros_ec_read_flashinfo(struct cros_ec_dev *dev,
                          struct ec_response_flash_info *info)
{
        int ret;

        ret = ec_command(dev, EC_CMD_FLASH_INFO, 0,
                         NULL, 0, info, sizeof(*info));
        if (ret < 0)
                return ret;

        return ret < sizeof(*info) ? -1 : 0;
}

int cros_ec_flash_write(struct cros_ec_dev *dev, const uint8_t *data,
                     uint32_t offset, uint32_t size)
{
        uint32_t burst = cros_ec_flash_write_burst_size(dev);
        uint32_t end, off;
        int ret;

        /*
         * TODO: round up to the nearest multiple of write size.  Can get away
         * without that on link right now because its write size is 4 bytes.
         */
        end = offset + size;
        for (off = offset; off < end; off += burst, data += burst) {
                uint32_t todo;

                /* If the data is empty, there is no point in programming it */
                todo = min(end - off, burst);
                if (dev->optimise_flash_write &&
                                cros_ec_data_is_erased((uint32_t *)data, todo))
                        continue;

                ret = cros_ec_flash_write_block(dev, data, off, todo);
                if (ret)
                        return ret;
        }

        return 0;
}

/**
 * Read a single block from the flash
 *
 * Read a block of data from the EC flash. The size must not exceed the flash
 * write block size which you can obtain from cros_ec_flash_write_burst_size().
 *
 * The offset starts at 0. You can obtain the region information from
 * cros_ec_flash_offset() to find out where to read for a particular region.
 *
 * @param dev           CROS-EC device
 * @param data          Pointer to data buffer to read into
 * @param offset        Offset within flash to read from
 * @param size          Number of bytes to read
 * @return 0 if ok, -1 on error
 */
static int cros_ec_flash_read_block(struct cros_ec_dev *dev, uint8_t *data,
                                 uint32_t offset, uint32_t size)
{
        struct ec_params_flash_read p;

        p.offset = offset;
        p.size = size;

        return ec_command(dev, EC_CMD_FLASH_READ, 0,
                          &p, sizeof(p), data, size) >= 0 ? 0 : -1;
}

int cros_ec_flash_read(struct cros_ec_dev *dev, uint8_t *data, uint32_t offset,
                    uint32_t size)
{
        uint32_t burst = cros_ec_flash_write_burst_size(dev);
        uint32_t end, off;
        int ret;

        end = offset + size;
        for (off = offset; off < end; off += burst, data += burst) {
                ret = cros_ec_flash_read_block(dev, data, off,
                                            min(end - off, burst));
                if (ret)
                        return ret;
        }

        return 0;
}

int cros_ec_flash_update_rw(struct cros_ec_dev *dev,
                         const uint8_t *image, int image_size)
{
        uint32_t rw_offset, rw_size;
        int ret;

        if (cros_ec_flash_offset(dev, EC_FLASH_REGION_RW, &rw_offset, &rw_size))
                return -1;
        if (image_size > (int)rw_size)
                return -1;

        /* Invalidate the existing hash, just in case the AP reboots
         * unexpectedly during the update. If that happened, the EC RW firmware
         * would be invalid, but the EC would still have the original hash.
         */
        ret = cros_ec_invalidate_hash(dev);
        if (ret)
                return ret;

        /*
         * Erase the entire RW section, so that the EC doesn't see any garbage
         * past the new image if it's smaller than the current image.
         *
         * TODO: could optimize this to erase just the current image, since
         * presumably everything past that is 0xff's.  But would still need to
         * round up to the nearest multiple of erase size.
         */
        ret = cros_ec_flash_erase(dev, rw_offset, rw_size);
        if (ret)
                return ret;

        /* Write the image */
        ret = cros_ec_flash_write(dev, image, rw_offset, image_size);
        if (ret)
                return ret;

        return 0;
}

int cros_ec_read_vbnvcontext(struct cros_ec_dev *dev, uint8_t *block)
{
        struct ec_params_vbnvcontext p;
        int len;

        p.op = EC_VBNV_CONTEXT_OP_READ;

        len = ec_command(dev, EC_CMD_VBNV_CONTEXT, EC_VER_VBNV_CONTEXT,
                        &p, sizeof(p), block, EC_VBNV_BLOCK_SIZE);
        if (len < EC_VBNV_BLOCK_SIZE)
                return -1;

        return 0;
}

int cros_ec_write_vbnvcontext(struct cros_ec_dev *dev, const uint8_t *block)
{
        struct ec_params_vbnvcontext p;
        int len;

        p.op = EC_VBNV_CONTEXT_OP_WRITE;
        memcpy(p.block, block, sizeof(p.block));

        len = ec_command_inptr(dev, EC_CMD_VBNV_CONTEXT, EC_VER_VBNV_CONTEXT,
                        &p, sizeof(p), NULL, 0);
        if (len < 0)
                return -1;

        return 0;
}

int cros_ec_set_ldo(struct udevice *dev, uint8_t index, uint8_t state)
{
        struct cros_ec_dev *cdev = dev_get_uclass_priv(dev);
        struct ec_params_ldo_set params;

        params.index = index;
        params.state = state;

        if (ec_command_inptr(cdev, EC_CMD_LDO_SET, 0, &params, sizeof(params),
                             NULL, 0))
                return -1;

        return 0;
}

int cros_ec_get_ldo(struct udevice *dev, uint8_t index, uint8_t *state)
{
        struct cros_ec_dev *cdev = dev_get_uclass_priv(dev);
        struct ec_params_ldo_get params;
        struct ec_response_ldo_get *resp;

        params.index = index;

        if (ec_command_inptr(cdev, EC_CMD_LDO_GET, 0, &params, sizeof(params),
                             (uint8_t **)&resp, sizeof(*resp)) !=
                             sizeof(*resp))
                return -1;

        *state = resp->state;

        return 0;
}

int cros_ec_register(struct udevice *dev)
{
        struct cros_ec_dev *cdev = dev_get_uclass_priv(dev);
        char id[MSG_BYTES];

        cdev->dev = dev;
        gpio_request_by_name(dev, "ec-interrupt", 0, &cdev->ec_int,
                             GPIOD_IS_IN);
        cdev->optimise_flash_write = dev_read_bool(dev, "optimise-flash-write");

        if (cros_ec_check_version(cdev)) {
                debug("%s: Could not detect CROS-EC version\n", __func__);
                return -CROS_EC_ERR_CHECK_VERSION;
        }

        if (cros_ec_read_id(cdev, id, sizeof(id))) {
                debug("%s: Could not read KBC ID\n", __func__);
                return -CROS_EC_ERR_READ_ID;
        }

        /* Remember this device for use by the cros_ec command */
        debug("Google Chrome EC v%d CROS-EC driver ready, id '%s'\n",
              cdev->protocol_version, id);

        return 0;
}

int cros_ec_decode_ec_flash(struct udevice *dev, struct fdt_cros_ec *config)
{
        ofnode flash_node, node;

        flash_node = dev_read_subnode(dev, "flash");
        if (!ofnode_valid(flash_node)) {
                debug("Failed to find flash node\n");
                return -1;
        }

        if (of_read_fmap_entry(flash_node, "flash", &config->flash)) {
                debug("Failed to decode flash node in chrome-ec\n");
                return -1;
        }

        config->flash_erase_value = ofnode_read_s32_default(flash_node,
                                                            "erase-value", -1);
        ofnode_for_each_subnode(node, flash_node) {
                const char *name = ofnode_get_name(node);
                enum ec_flash_region region;

                if (0 == strcmp(name, "ro")) {
                        region = EC_FLASH_REGION_RO;
                } else if (0 == strcmp(name, "rw")) {
                        region = EC_FLASH_REGION_RW;
                } else if (0 == strcmp(name, "wp-ro")) {
                        region = EC_FLASH_REGION_WP_RO;
                } else {
                        debug("Unknown EC flash region name '%s'\n", name);
                        return -1;
                }

                if (of_read_fmap_entry(node, "reg", &config->region[region])) {
                        debug("Failed to decode flash region in chrome-ec'\n");
                        return -1;
                }
        }

        return 0;
}

int cros_ec_i2c_tunnel(struct udevice *dev, int port, struct i2c_msg *in,
                       int nmsgs)
{
        struct cros_ec_dev *cdev = dev_get_uclass_priv(dev);
        union {
                struct ec_params_i2c_passthru p;
                uint8_t outbuf[EC_PROTO2_MAX_PARAM_SIZE];
        } params;
        union {
                struct ec_response_i2c_passthru r;
                uint8_t inbuf[EC_PROTO2_MAX_PARAM_SIZE];
        } response;
        struct ec_params_i2c_passthru *p = &params.p;
        struct ec_response_i2c_passthru *r = &response.r;
        struct ec_params_i2c_passthru_msg *msg;
        uint8_t *pdata, *read_ptr = NULL;
        int read_len;
        int size;
        int rv;
        int i;

        p->port = port;

        p->num_msgs = nmsgs;
        size = sizeof(*p) + p->num_msgs * sizeof(*msg);

        /* Create a message to write the register address and optional data */
        pdata = (uint8_t *)p + size;

        read_len = 0;
        for (i = 0, msg = p->msg; i < nmsgs; i++, msg++, in++) {
                bool is_read = in->flags & I2C_M_RD;

                msg->addr_flags = in->addr;
                msg->len = in->len;
                if (is_read) {
                        msg->addr_flags |= EC_I2C_FLAG_READ;
                        read_len += in->len;
                        read_ptr = in->buf;
                        if (sizeof(*r) + read_len > sizeof(response)) {
                                puts("Read length too big for buffer\n");
                                return -1;
                        }
                } else {
                        if (pdata - (uint8_t *)p + in->len > sizeof(params)) {
                                puts("Params too large for buffer\n");
                                return -1;
                        }
                        memcpy(pdata, in->buf, in->len);
                        pdata += in->len;
                }
        }

        rv = ec_command(cdev, EC_CMD_I2C_PASSTHRU, 0, p, pdata - (uint8_t *)p,
                        r, sizeof(*r) + read_len);
        if (rv < 0)
                return rv;

        /* Parse response */
        if (r->i2c_status & EC_I2C_STATUS_ERROR) {
                printf("Transfer failed with status=0x%x\n", r->i2c_status);
                return -1;
        }

        if (rv < sizeof(*r) + read_len) {
                puts("Truncated read response\n");
                return -1;
        }

        /* We only support a single read message for each transfer */
        if (read_len)
                memcpy(read_ptr, r->data, read_len);

        return 0;
}

UCLASS_DRIVER(cros_ec) = {
        .id             = UCLASS_CROS_EC,
        .name           = "cros_ec",
        .per_device_auto_alloc_size = sizeof(struct cros_ec_dev),
        .post_bind      = dm_scan_fdt_dev,
};