Introduce a new transport procotol between EC and host.
Acked-by: Enric Balletbo i Serra enric.balletbo@collabora.com Acked-by: Benson Leung bleung@chromium.org Reviewed-by: Fabien Lahoudere fabien.lahoudere@collabora.com Signed-off-by: Gwendal Grignou gwendal@chromium.org --- include/linux/mfd/cros_ec_commands.h | 143 ++++++++++++++++++++++++++- 1 file changed, 141 insertions(+), 2 deletions(-)
diff --git a/include/linux/mfd/cros_ec_commands.h b/include/linux/mfd/cros_ec_commands.h index 76943e64998a..40a8069a58e8 100644 --- a/include/linux/mfd/cros_ec_commands.h +++ b/include/linux/mfd/cros_ec_commands.h @@ -455,7 +455,10 @@ #define EC_LPC_STATUS_BUSY_MASK \ (EC_LPC_STATUS_FROM_HOST | EC_LPC_STATUS_PROCESSING)
-/* Host command response codes */ +/* + * Host command response codes (16-bit). Note that response codes should be + * stored in a uint16_t rather than directly in a value of this type. + */ enum ec_status { EC_RES_SUCCESS = 0, EC_RES_INVALID_COMMAND = 1, @@ -471,7 +474,13 @@ enum ec_status { EC_RES_OVERFLOW = 11, /* Table / data overflow */ EC_RES_INVALID_HEADER = 12, /* Header contains invalid data */ EC_RES_REQUEST_TRUNCATED = 13, /* Didn't get the entire request */ - EC_RES_RESPONSE_TOO_BIG = 14 /* Response was too big to handle */ + EC_RES_RESPONSE_TOO_BIG = 14, /* Response was too big to handle */ + EC_RES_BUS_ERROR = 15, /* Communications bus error */ + EC_RES_BUSY = 16, /* Up but too busy. Should retry */ + EC_RES_INVALID_HEADER_VERSION = 17, /* Header version invalid */ + EC_RES_INVALID_HEADER_CRC = 18, /* Header CRC invalid */ + EC_RES_INVALID_DATA_CRC = 19, /* Data CRC invalid */ + EC_RES_DUP_UNAVAILABLE = 20, /* Can't resend response */ };
/* @@ -744,6 +753,136 @@ struct ec_host_response { uint16_t reserved; } __ec_align4;
+/*****************************************************************************/ + +/* + * Host command protocol V4. + * + * Packets always start with a request or response header. They are followed + * by data_len bytes of data. If the data_crc_present flag is set, the data + * bytes are followed by a CRC-8 of that data, using using x^8 + x^2 + x + 1 + * polynomial. + * + * Host algorithm when sending a request q: + * + * 101) tries_left=(some value, e.g. 3); + * 102) q.seq_num++ + * 103) q.seq_dup=0 + * 104) Calculate q.header_crc. + * 105) Send request q to EC. + * 106) Wait for response r. Go to 201 if received or 301 if timeout. + * + * 201) If r.struct_version != 4, go to 301. + * 202) If r.header_crc mismatches calculated CRC for r header, go to 301. + * 203) If r.data_crc_present and r.data_crc mismatches, go to 301. + * 204) If r.seq_num != q.seq_num, go to 301. + * 205) If r.seq_dup == q.seq_dup, return success. + * 207) If r.seq_dup == 1, go to 301. + * 208) Return error. + * + * 301) If --tries_left <= 0, return error. + * 302) If q.seq_dup == 1, go to 105. + * 303) q.seq_dup = 1 + * 304) Go to 104. + * + * EC algorithm when receiving a request q. + * EC has response buffer r, error buffer e. + * + * 101) If q.struct_version != 4, set e.result = EC_RES_INVALID_HEADER_VERSION + * and go to 301 + * 102) If q.header_crc mismatches calculated CRC, set e.result = + * EC_RES_INVALID_HEADER_CRC and go to 301 + * 103) If q.data_crc_present, calculate data CRC. If that mismatches the CRC + * byte at the end of the packet, set e.result = EC_RES_INVALID_DATA_CRC + * and go to 301. + * 104) If q.seq_dup == 0, go to 201. + * 105) If q.seq_num != r.seq_num, go to 201. + * 106) If q.seq_dup == r.seq_dup, go to 205, else go to 203. + * + * 201) Process request q into response r. + * 202) r.seq_num = q.seq_num + * 203) r.seq_dup = q.seq_dup + * 204) Calculate r.header_crc + * 205) If r.data_len > 0 and data is no longer available, set e.result = + * EC_RES_DUP_UNAVAILABLE and go to 301. + * 206) Send response r. + * + * 301) e.seq_num = q.seq_num + * 302) e.seq_dup = q.seq_dup + * 303) Calculate e.header_crc. + * 304) Send error response e. + */ + +/* Version 4 request from host */ +struct ec_host_request4 { + /* + * bits 0-3: struct_version: Structure version (=4) + * bit 4: is_response: Is response (=0) + * bits 5-6: seq_num: Sequence number + * bit 7: seq_dup: Sequence duplicate flag + */ + uint8_t fields0; + + /* + * bits 0-4: command_version: Command version + * bits 5-6: Reserved (set 0, ignore on read) + * bit 7: data_crc_present: Is data CRC present after data + */ + uint8_t fields1; + + /* Command code (EC_CMD_*) */ + uint16_t command; + + /* Length of data which follows this header (not including data CRC) */ + uint16_t data_len; + + /* Reserved (set 0, ignore on read) */ + uint8_t reserved; + + /* CRC-8 of above fields, using x^8 + x^2 + x + 1 polynomial */ + uint8_t header_crc; +} __ec_align4; + +/* Version 4 response from EC */ +struct ec_host_response4 { + /* + * bits 0-3: struct_version: Structure version (=4) + * bit 4: is_response: Is response (=1) + * bits 5-6: seq_num: Sequence number + * bit 7: seq_dup: Sequence duplicate flag + */ + uint8_t fields0; + + /* + * bits 0-6: Reserved (set 0, ignore on read) + * bit 7: data_crc_present: Is data CRC present after data + */ + uint8_t fields1; + + /* Result code (EC_RES_*) */ + uint16_t result; + + /* Length of data which follows this header (not including data CRC) */ + uint16_t data_len; + + /* Reserved (set 0, ignore on read) */ + uint8_t reserved; + + /* CRC-8 of above fields, using x^8 + x^2 + x + 1 polynomial */ + uint8_t header_crc; +} __ec_align4; + +/* Fields in fields0 byte */ +#define EC_PACKET4_0_STRUCT_VERSION_MASK 0x0f +#define EC_PACKET4_0_IS_RESPONSE_MASK 0x10 +#define EC_PACKET4_0_SEQ_NUM_SHIFT 5 +#define EC_PACKET4_0_SEQ_NUM_MASK 0x60 +#define EC_PACKET4_0_SEQ_DUP_MASK 0x80 + +/* Fields in fields1 byte */ +#define EC_PACKET4_1_COMMAND_VERSION_MASK 0x1f /* (request only) */ +#define EC_PACKET4_1_DATA_CRC_PRESENT_MASK 0x80 + /*****************************************************************************/ /* * Notes on commands: