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    Subject[RESEND PATCH 7/8] mfd: cros_ec: add proto v3 skeleton
    Date
    From: Stephen Barber <smbarber@chromium.org>

    Add support in cros_ec.c to handle EC host command protocol v3.
    For v3+, probe for maximum shared protocol version and max
    request, response, and passthrough sizes. For now, this will
    always fall back to v2, since there is no bus-specific code
    for handling proto v3 packets.

    Signed-off-by: Stephen Barber <smbarber@chromium.org>
    Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
    ---
    drivers/mfd/cros_ec.c | 363 +++++++++++++++++++++++++++++-----
    drivers/mfd/cros_ec_i2c.c | 4 +
    drivers/mfd/cros_ec_spi.c | 7 +-
    drivers/platform/chrome/cros_ec_lpc.c | 4 +
    include/linux/mfd/cros_ec.h | 20 +-
    5 files changed, 347 insertions(+), 51 deletions(-)

    diff --git a/drivers/mfd/cros_ec.c b/drivers/mfd/cros_ec.c
    index 70f6e55a096e..0972a7d36199 100644
    --- a/drivers/mfd/cros_ec.c
    +++ b/drivers/mfd/cros_ec.c
    @@ -30,11 +30,281 @@

    static int dev_id;

    +static int prepare_packet(struct cros_ec_device *ec_dev,
    + struct cros_ec_command *msg)
    +{
    + struct ec_host_request *request;
    + u8 *out;
    + int i;
    + u8 csum = 0;
    +
    + BUG_ON(ec_dev->proto_version != EC_HOST_REQUEST_VERSION);
    + BUG_ON(msg->outsize + sizeof(*request) > ec_dev->dout_size);
    +
    + out = ec_dev->dout;
    + request = (struct ec_host_request *)out;
    + request->struct_version = EC_HOST_REQUEST_VERSION;
    + request->checksum = 0;
    + request->command = msg->command;
    + request->command_version = msg->version;
    + request->reserved = 0;
    + request->data_len = msg->outsize;
    +
    + for (i = 0; i < sizeof(*request); i++)
    + csum += out[i];
    +
    + /* Copy data and update checksum */
    + memcpy(out + sizeof(*request), msg->data, msg->outsize);
    + for (i = 0; i < msg->outsize; i++)
    + csum += msg->data[i];
    +
    + request->checksum = -csum;
    +
    + return sizeof(*request) + msg->outsize;
    +}
    +
    +static int send_command(struct cros_ec_device *ec_dev,
    + struct cros_ec_command *msg)
    +{
    + int ret;
    +
    + if (ec_dev->proto_version > 2)
    + ret = ec_dev->pkt_xfer(ec_dev, msg);
    + else
    + ret = ec_dev->cmd_xfer(ec_dev, msg);
    +
    + if (msg->result == EC_RES_IN_PROGRESS) {
    + int i;
    + struct cros_ec_command *status_msg;
    + struct ec_response_get_comms_status *status;
    +
    + status_msg = kzalloc(sizeof(*status_msg) + sizeof(*status),
    + GFP_KERNEL);
    + if (!status_msg)
    + return -ENOMEM;
    +
    + status_msg->command = EC_CMD_GET_COMMS_STATUS;
    + status_msg->insize = sizeof(*status);
    +
    + /*
    + * Query the EC's status until it's no longer busy or
    + * we encounter an error.
    + */
    + for (i = 0; i < EC_COMMAND_RETRIES; i++) {
    + usleep_range(10000, 11000);
    +
    + ret = ec_dev->cmd_xfer(ec_dev, status_msg);
    + if (ret < 0)
    + break;
    +
    + msg->result = status_msg->result;
    + if (status_msg->result != EC_RES_SUCCESS)
    + break;
    +
    + status = (struct ec_response_get_comms_status *)
    + status_msg->data;
    + if (!(status->flags & EC_COMMS_STATUS_PROCESSING))
    + break;
    + }
    +
    + kfree(status_msg);
    + }
    +
    + return ret;
    +}
    +
    +static int cros_ec_host_command_proto_probe(struct cros_ec_device *ec_dev,
    + int devidx,
    + struct cros_ec_command *msg)
    +{
    + /*
    + * Try using v3+ to query for supported protocols. If this
    + * command fails, fall back to v2. Returns the highest protocol
    + * supported by the EC.
    + * Also sets the max request/response/passthru size.
    + */
    + int ret;
    +
    + if (!ec_dev->pkt_xfer)
    + return -EPROTONOSUPPORT;
    +
    + memset(msg, 0, sizeof(*msg));
    + msg->command = EC_CMD_PASSTHRU_OFFSET(devidx) | EC_CMD_GET_PROTOCOL_INFO;
    + msg->insize = sizeof(struct ec_response_get_protocol_info);
    +
    + ret = send_command(ec_dev, msg);
    +
    + if (ret < 0) {
    + dev_dbg(ec_dev->dev,
    + "failed to probe for EC[%d] protocol version: %d\n",
    + devidx, ret);
    + return ret;
    + }
    +
    + if (devidx > 0 && msg->result == EC_RES_INVALID_COMMAND)
    + return -ENODEV;
    + else if (msg->result != EC_RES_SUCCESS)
    + return msg->result;
    +
    + return 0;
    +}
    +
    +static int cros_ec_host_command_proto_probe_v2(struct cros_ec_device *ec_dev)
    +{
    + struct cros_ec_command *msg;
    + struct ec_params_hello *hello_params;
    + struct ec_response_hello *hello_response;
    + int ret;
    + int len = max(sizeof(*hello_params), sizeof(*hello_response));
    +
    + msg = kzalloc(sizeof(*msg) + len, GFP_KERNEL);
    + if (!msg)
    + return -ENOMEM;
    +
    + msg->command = EC_CMD_HELLO;
    + hello_params = (struct ec_params_hello *)msg->data;
    + msg->outsize = sizeof(*hello_params);
    + hello_response = (struct ec_response_hello *)msg->data;
    + msg->insize = sizeof(*hello_response);
    +
    + hello_params->in_data = 0xa0b0c0d0;
    +
    + ret = send_command(ec_dev, msg);
    +
    + if (ret < 0) {
    + dev_dbg(ec_dev->dev,
    + "EC failed to respond to v2 hello: %d\n",
    + ret);
    + goto exit;
    + } else if (msg->result != EC_RES_SUCCESS) {
    + dev_err(ec_dev->dev,
    + "EC responded to v2 hello with error: %d\n",
    + msg->result);
    + ret = msg->result;
    + goto exit;
    + } else if (hello_response->out_data != 0xa1b2c3d4) {
    + dev_err(ec_dev->dev,
    + "EC responded to v2 hello with bad result: %u\n",
    + hello_response->out_data);
    + ret = -EBADMSG;
    + goto exit;
    + }
    +
    + ret = 0;
    +
    +exit:
    + kfree(msg);
    + return ret;
    +}
    +
    +static int cros_ec_probe_all(struct cros_ec_device *ec_dev)
    +{
    + struct device *dev = ec_dev->dev;
    + struct cros_ec_command *proto_msg;
    + struct ec_response_get_protocol_info *proto_info;
    + int ret;
    +
    + proto_msg = kzalloc(sizeof(*proto_msg) + sizeof(*proto_info),
    + GFP_KERNEL);
    + if (!proto_msg)
    + return -ENOMEM;
    +
    + /* First try sending with proto v3. */
    + ec_dev->proto_version = 3;
    + ret = cros_ec_host_command_proto_probe(ec_dev, 0, proto_msg);
    +
    + if (ret == 0) {
    + proto_info = (struct ec_response_get_protocol_info *)
    + proto_msg->data;
    + ec_dev->max_request = proto_info->max_request_packet_size -
    + sizeof(struct ec_host_request);
    + ec_dev->max_response = proto_info->max_response_packet_size -
    + sizeof(struct ec_host_response);
    + ec_dev->proto_version =
    + min(EC_HOST_REQUEST_VERSION,
    + fls(proto_info->protocol_versions) - 1);
    + dev_dbg(ec_dev->dev,
    + "using proto v%u\n",
    + ec_dev->proto_version);
    +
    + ec_dev->din_size = ec_dev->max_response +
    + sizeof(struct ec_host_response) +
    + EC_MAX_RESPONSE_OVERHEAD;
    + ec_dev->dout_size = ec_dev->max_request +
    + sizeof(struct ec_host_request) +
    + EC_MAX_REQUEST_OVERHEAD;
    +
    + /*
    + * Check for PD
    + */
    + ret = cros_ec_host_command_proto_probe(ec_dev, 1, proto_msg);
    +
    + if (ret) {
    + dev_dbg(ec_dev->dev, "no PD chip found: %d\n", ret);
    + ec_dev->max_passthru = 0;
    + } else {
    + dev_dbg(ec_dev->dev, "found PD chip\n");
    + ec_dev->max_passthru =
    + proto_info->max_request_packet_size -
    + sizeof(struct ec_host_request);
    + }
    + } else {
    + /* Try probing with a v2 hello message. */
    + ec_dev->proto_version = 2;
    + ret = cros_ec_host_command_proto_probe_v2(ec_dev);
    +
    + if (ret == 0) {
    + /* V2 hello succeeded. */
    + dev_dbg(ec_dev->dev, "falling back to proto v2\n");
    +
    + ec_dev->max_request = EC_PROTO2_MAX_PARAM_SIZE;
    + ec_dev->max_response = EC_PROTO2_MAX_PARAM_SIZE;
    + ec_dev->max_passthru = 0;
    + ec_dev->pkt_xfer = NULL;
    + ec_dev->din_size = EC_MSG_BYTES;
    + ec_dev->dout_size = EC_MSG_BYTES;
    + } else {
    + /*
    + * It's possible for a probe to occur too early when
    + * the EC isn't listening. If this happens, we'll
    + * probe later when the first command is run.
    + */
    + ec_dev->proto_version = EC_PROTO_VERSION_UNKNOWN;
    + dev_dbg(ec_dev->dev, "EC probe failed: %d\n", ret);
    + goto exit;
    + }
    + }
    +
    + devm_kfree(dev, ec_dev->din);
    + devm_kfree(dev, ec_dev->dout);
    +
    + ec_dev->din = devm_kzalloc(dev, ec_dev->din_size, GFP_KERNEL);
    + if (!ec_dev->din) {
    + ret = -ENOMEM;
    + goto exit;
    + }
    +
    + ec_dev->dout = devm_kzalloc(dev, ec_dev->dout_size, GFP_KERNEL);
    + if (!ec_dev->dout) {
    + devm_kfree(dev, ec_dev->din);
    + ret = -ENOMEM;
    + goto exit;
    + }
    +
    +exit:
    + kfree(proto_msg);
    + return ret;
    +}
    +
    int cros_ec_prepare_tx(struct cros_ec_device *ec_dev,
    struct cros_ec_command *msg)
    {
    - uint8_t *out;
    - int csum, i;
    + u8 *out;
    + u8 csum;
    + int i;
    +
    + if (ec_dev->proto_version > 2)
    + return prepare_packet(ec_dev, msg);

    BUG_ON(msg->outsize > EC_PROTO2_MAX_PARAM_SIZE);
    out = ec_dev->dout;
    @@ -44,7 +314,7 @@ int cros_ec_prepare_tx(struct cros_ec_device *ec_dev,
    csum = out[0] + out[1] + out[2];
    for (i = 0; i < msg->outsize; i++)
    csum += out[EC_MSG_TX_HEADER_BYTES + i] = msg->data[i];
    - out[EC_MSG_TX_HEADER_BYTES + msg->outsize] = (uint8_t)(csum & 0xff);
    + out[EC_MSG_TX_HEADER_BYTES + msg->outsize] = csum;

    return EC_MSG_TX_PROTO_BYTES + msg->outsize;
    }
    @@ -74,46 +344,43 @@ int cros_ec_cmd_xfer(struct cros_ec_device *ec_dev,
    int ret;

    mutex_lock(&ec_dev->lock);
    - ret = ec_dev->cmd_xfer(ec_dev, msg);
    - if (msg->result == EC_RES_IN_PROGRESS) {
    - int i;
    - struct cros_ec_command *status_msg;
    - struct ec_response_get_comms_status *status;

    - status_msg = kzalloc(sizeof(*status_msg) + sizeof(*status),
    - GFP_KERNEL);
    - if (!status_msg) {
    - ret = -ENOMEM;
    - goto exit;
    + if (ec_dev->proto_version == EC_PROTO_VERSION_UNKNOWN) {
    + ret = cros_ec_probe_all(ec_dev);
    + if (ret) {
    + dev_err(ec_dev->dev,
    + "EC version unknown and probe failed; aborting command\n");
    + mutex_unlock(&ec_dev->lock);
    + return ret;
    }
    + }

    - status_msg->command = EC_CMD_GET_COMMS_STATUS;
    - status_msg->insize = sizeof(*status);
    -
    - /*
    - * Query the EC's status until it's no longer busy or
    - * we encounter an error.
    - */
    - for (i = 0; i < EC_COMMAND_RETRIES; i++) {
    - usleep_range(10000, 11000);
    -
    - ret = ec_dev->cmd_xfer(ec_dev, status_msg);
    - if (ret < 0)
    - break;
    -
    - msg->result = status_msg->result;
    - if (status_msg->result != EC_RES_SUCCESS)
    - break;
    + if (msg->insize > ec_dev->max_response) {
    + dev_dbg(ec_dev->dev, "clamping message receive buffer\n");
    + msg->insize = ec_dev->max_response;
    + }

    - status = (struct ec_response_get_comms_status *)
    - status_msg->data;
    - if (!(status->flags & EC_COMMS_STATUS_PROCESSING))
    - break;
    + if (msg->command < EC_CMD_PASSTHRU_OFFSET(1)) {
    + if (msg->outsize > ec_dev->max_request) {
    + dev_err(ec_dev->dev,
    + "request of size %u is too big (max: %u)\n",
    + msg->outsize,
    + ec_dev->max_request);
    + mutex_unlock(&ec_dev->lock);
    + return -EMSGSIZE;
    + }
    + } else {
    + if (msg->outsize > ec_dev->max_passthru) {
    + dev_err(ec_dev->dev,
    + "passthru rq of size %u is too big (max: %u)\n",
    + msg->outsize,
    + ec_dev->max_passthru);
    + mutex_unlock(&ec_dev->lock);
    + return -EMSGSIZE;
    }
    -
    - kfree(status_msg);
    }
    -exit:
    +
    + ret = send_command(ec_dev, msg);
    mutex_unlock(&ec_dev->lock);

    return ret;
    @@ -132,21 +399,23 @@ int cros_ec_register(struct cros_ec_device *ec_dev)
    struct device *dev = ec_dev->dev;
    int err = 0;

    + ec_dev->max_request = sizeof(struct ec_params_hello);
    + ec_dev->max_response = sizeof(struct ec_response_get_protocol_info);
    + ec_dev->max_passthru = 0;
    ec_dev->id = dev_id;

    - if (ec_dev->din_size) {
    - ec_dev->din = devm_kzalloc(dev, ec_dev->din_size, GFP_KERNEL);
    - if (!ec_dev->din)
    - return -ENOMEM;
    - }
    - if (ec_dev->dout_size) {
    - ec_dev->dout = devm_kzalloc(dev, ec_dev->dout_size, GFP_KERNEL);
    - if (!ec_dev->dout)
    - return -ENOMEM;
    - }
    + ec_dev->din = devm_kzalloc(dev, ec_dev->din_size, GFP_KERNEL);
    + if (!ec_dev->din)
    + return -ENOMEM;
    +
    + ec_dev->dout = devm_kzalloc(dev, ec_dev->dout_size, GFP_KERNEL);
    + if (!ec_dev->dout)
    + return -ENOMEM;

    mutex_init(&ec_dev->lock);

    + cros_ec_probe_all(ec_dev);
    +
    err = mfd_add_devices(dev, ec_dev->id, cros_devs,
    ARRAY_SIZE(cros_devs),
    NULL, ec_dev->irq, NULL);
    diff --git a/drivers/mfd/cros_ec_i2c.c b/drivers/mfd/cros_ec_i2c.c
    index fbf7819f5de5..b400bfa2772a 100644
    --- a/drivers/mfd/cros_ec_i2c.c
    +++ b/drivers/mfd/cros_ec_i2c.c
    @@ -143,8 +143,12 @@ static int cros_ec_i2c_probe(struct i2c_client *client,
    ec_dev->priv = client;
    ec_dev->irq = client->irq;
    ec_dev->cmd_xfer = cros_ec_cmd_xfer_i2c;
    + ec_dev->pkt_xfer = NULL;
    ec_dev->ec_name = client->name;
    ec_dev->phys_name = client->adapter->name;
    + 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);

    err = cros_ec_register(ec_dev);
    if (err) {
    diff --git a/drivers/mfd/cros_ec_spi.c b/drivers/mfd/cros_ec_spi.c
    index 573730fec947..04da2f288ef8 100644
    --- a/drivers/mfd/cros_ec_spi.c
    +++ b/drivers/mfd/cros_ec_spi.c
    @@ -361,10 +361,13 @@ static int cros_ec_spi_probe(struct spi_device *spi)
    ec_dev->priv = ec_spi;
    ec_dev->irq = spi->irq;
    ec_dev->cmd_xfer = cros_ec_cmd_xfer_spi;
    + ec_dev->pkt_xfer = NULL;
    ec_dev->ec_name = ec_spi->spi->modalias;
    ec_dev->phys_name = dev_name(&ec_spi->spi->dev);
    - ec_dev->din_size = EC_MSG_BYTES + EC_MSG_PREAMBLE_COUNT;
    - ec_dev->dout_size = EC_MSG_BYTES;
    + ec_dev->din_size = EC_MSG_PREAMBLE_COUNT +
    + sizeof(struct ec_host_response) +
    + sizeof(struct ec_response_get_protocol_info);
    + ec_dev->dout_size = sizeof(struct ec_host_request);

    err = cros_ec_register(ec_dev);
    if (err) {
    diff --git a/drivers/platform/chrome/cros_ec_lpc.c b/drivers/platform/chrome/cros_ec_lpc.c
    index 32b1df29fc58..d56dfb9dd463 100644
    --- a/drivers/platform/chrome/cros_ec_lpc.c
    +++ b/drivers/platform/chrome/cros_ec_lpc.c
    @@ -205,7 +205,11 @@ static int cros_ec_lpc_probe(struct platform_device *pdev)
    ec_dev->ec_name = pdev->name;
    ec_dev->phys_name = dev_name(dev);
    ec_dev->cmd_xfer = cros_ec_cmd_xfer_lpc;
    + ec_dev->pkt_xfer = NULL;
    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) {
    diff --git a/include/linux/mfd/cros_ec.h b/include/linux/mfd/cros_ec.h
    index 2bee6ac74ffb..f27ce4b7736b 100644
    --- a/include/linux/mfd/cros_ec.h
    +++ b/include/linux/mfd/cros_ec.h
    @@ -22,6 +22,15 @@
    #include <linux/mutex.h>

    /*
    + * Max bus-specific overhead incurred by request/responses.
    + * I2C requires 1 additional byte for requests.
    + * I2C requires 2 additional bytes for responses.
    + * */
    +#define EC_PROTO_VERSION_UNKNOWN 0
    +#define EC_MAX_REQUEST_OVERHEAD 1
    +#define EC_MAX_RESPONSE_OVERHEAD 2
    +
    +/*
    * Command interface between EC and AP, for LPC, I2C and SPI interfaces.
    */
    enum {
    @@ -89,6 +98,7 @@ struct cros_ec_command {
    * Returns the number of bytes received if the communication succeeded, but
    * that doesn't mean the EC was happy with the command. The caller
    * should check msg.result for the EC's result code.
    + * @pkt_xfer: send packet to EC and get response
    * @lock: one transaction at a time
    */
    struct cros_ec_device {
    @@ -105,16 +115,22 @@ struct cros_ec_device {
    unsigned int bytes, void *dest);

    /* These are used to implement the platform-specific interface */
    + u16 max_request;
    + u16 max_response;
    + u16 max_passthru;
    + u16 proto_version;
    void *priv;
    int irq;
    int id;
    - uint8_t *din;
    - uint8_t *dout;
    + u8 *din;
    + u8 *dout;
    int din_size;
    int dout_size;
    bool wake_enabled;
    int (*cmd_xfer)(struct cros_ec_device *ec,
    struct cros_ec_command *msg);
    + int (*pkt_xfer)(struct cros_ec_device *ec,
    + struct cros_ec_command *msg);
    struct mutex lock;
    };

    --
    2.1.4


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