mfd: cros_ec: add proto v3 skeleton

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>
Reviewed-by: Gwendal Grignou <gwendal@chromium.org>
Tested-by: Gwendal Grignou <gwendal@chromium.org>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Acked-by: Lee Jones <lee.jones@linaro.org>
Acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

2 files changed, 307 insertions, 36 deletions

diff --git a/drivers/platform/chrome/cros_ec_lpc.c b/drivers/platform/chrome/cros_ec_lpc.c
index 4c7f0df33bf8..05aeb559275f 100644
--- a/drivers/platform/chrome/cros_ec_lpc.c
+++ b/drivers/platform/chrome/cros_ec_lpc.c
@@ -215,7 +215,11 @@ 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/drivers/platform/chrome/cros_ec_proto.c b/drivers/platform/chrome/cros_ec_proto.c
index 58e98a24fd08..990308ca384f 100644
--- a/drivers/platform/chrome/cros_ec_proto.c
+++ b/drivers/platform/chrome/cros_ec_proto.c
@@ -22,11 +22,100 @@
 
 #define EC_COMMAND_RETRIES      50
 
+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 = kmalloc(sizeof(*status_msg) + sizeof(*status),
+                                     GFP_KERNEL);
+                if (!status_msg)
+                        return -ENOMEM;
+
+                status_msg->version = 0;
+                status_msg->command = EC_CMD_GET_COMMS_STATUS;
+                status_msg->insize = sizeof(*status);
+                status_msg->outsize = 0;
+
+                /*
+                 * 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;
+}
+
 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;
@@ -36,7 +125,7 @@ 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;
 }
@@ -60,54 +149,232 @@ int cros_ec_check_result(struct cros_ec_device *ec_dev,
 }
 EXPORT_SYMBOL(cros_ec_check_result);
 
-int cros_ec_cmd_xfer(struct cros_ec_device *ec_dev,
-                     struct cros_ec_command *msg)
+static int cros_ec_host_command_proto_query(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;
 
-        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;
+        if (!ec_dev->pkt_xfer)
+                return -EPROTONOSUPPORT;
 
-                status_msg = kmalloc(sizeof(*status_msg) + sizeof(*status),
-                                     GFP_KERNEL);
-                if (!status_msg) {
-                        ret = -ENOMEM;
-                        goto exit;
-                }
+        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);
 
-                status_msg->version = 0;
-                status_msg->command = EC_CMD_GET_COMMS_STATUS;
-                status_msg->insize = sizeof(*status);
-                status_msg->outsize = 0;
+        ret = send_command(ec_dev, msg);
+
+        if (ret < 0) {
+                dev_dbg(ec_dev->dev,
+                        "failed to check 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_query_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 = kmalloc(sizeof(*msg) + len, GFP_KERNEL);
+        if (!msg)
+                return -ENOMEM;
+
+        msg->version = 0;
+        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;
+}
+
+int cros_ec_query_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_query(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;
 
                 /*
-                 * Query the EC's status until it's no longer busy or
-                 * we encounter an error.
+                 * Check for PD
                  */
-                for (i = 0; i < EC_COMMAND_RETRIES; i++) {
-                        usleep_range(10000, 11000);
+                ret = cros_ec_host_command_proto_query(ec_dev, 1, proto_msg);
 
-                        ret = ec_dev->cmd_xfer(ec_dev, status_msg);
-                        if (ret < 0)
-                                break;
+                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 querying with a v2 hello message. */
+                ec_dev->proto_version = 2;
+                ret = cros_ec_host_command_proto_query_v2(ec_dev);
 
-                        msg->result = status_msg->result;
-                        if (status_msg->result != EC_RES_SUCCESS)
-                                break;
+                if (ret == 0) {
+                        /* V2 hello succeeded. */
+                        dev_dbg(ec_dev->dev, "falling back to proto v2\n");
 
-                        status = (struct ec_response_get_comms_status *)
-                                 status_msg->data;
-                        if (!(status->flags & EC_COMMS_STATUS_PROCESSING))
-                                break;
+                        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 test to occur too early when
+                         * the EC isn't listening. If this happens, we'll
+                         * test later when the first command is run.
+                         */
+                        ec_dev->proto_version = EC_PROTO_VERSION_UNKNOWN;
+                        dev_dbg(ec_dev->dev, "EC query failed: %d\n", ret);
+                        goto exit;
                 }
+        }
 
-                kfree(status_msg);
+        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;
+}
+EXPORT_SYMBOL(cros_ec_query_all);
+
+int cros_ec_cmd_xfer(struct cros_ec_device *ec_dev,
+                     struct cros_ec_command *msg)
+{
+        int ret;
+
+        mutex_lock(&ec_dev->lock);
+        if (ec_dev->proto_version == EC_PROTO_VERSION_UNKNOWN) {
+                ret = cros_ec_query_all(ec_dev);
+                if (ret) {
+                        dev_err(ec_dev->dev,
+                                "EC version unknown and query failed; aborting command\n");
+                        mutex_unlock(&ec_dev->lock);
+                        return ret;
+                }
+        }
+
+        if (msg->insize > ec_dev->max_response) {
+                dev_dbg(ec_dev->dev, "clamping message receive buffer\n");
+                msg->insize = ec_dev->max_response;
+        }
+
+        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;
+                }
+        }
+        ret = send_command(ec_dev, msg);
         mutex_unlock(&ec_dev->lock);
 
         return ret;