diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c index 0040981b6698..02e335a04f09 100644 --- a/drivers/i2c/i2c-core.c +++ b/drivers/i2c/i2c-core.c @@ -19,7 +19,8 @@ /* With some changes from Kyösti Mälkki . All SMBus-related things are written by Frodo Looijaard - SMBus 2.0 support by Mark Studebaker */ + SMBus 2.0 support by Mark Studebaker and + Jean Delvare */ #include #include @@ -830,101 +831,44 @@ crc8(u16 data) return (u8)(data >> 8); } -/* CRC over count bytes in the first array plus the bytes in the rest - array if it is non-null. rest[0] is the (length of rest) - 1 - and is included. */ -static u8 i2c_smbus_partial_pec(u8 crc, int count, u8 *first, u8 *rest) +/* Incremental CRC8 over count bytes in the array pointed to by p */ +static u8 i2c_smbus_pec(u8 crc, u8 *p, size_t count) { int i; for(i = 0; i < count; i++) - crc = crc8((crc ^ first[i]) << 8); - if(rest != NULL) - for(i = 0; i <= rest[0]; i++) - crc = crc8((crc ^ rest[i]) << 8); + crc = crc8((crc ^ p[i]) << 8); return crc; } -static u8 i2c_smbus_pec(int count, u8 *first, u8 *rest) +/* Assume a 7-bit address, which is reasonable for SMBus */ +static u8 i2c_smbus_msg_pec(u8 pec, struct i2c_msg *msg) { - return i2c_smbus_partial_pec(0, count, first, rest); + /* The address will be sent first */ + u8 addr = (msg->addr << 1) | !!(msg->flags & I2C_M_RD); + pec = i2c_smbus_pec(pec, &addr, 1); + + /* The data buffer follows */ + return i2c_smbus_pec(pec, msg->buf, msg->len); } -/* Returns new "size" (transaction type) - Note that we convert byte to byte_data and byte_data to word_data - rather than invent new xxx_PEC transactions. */ -static int i2c_smbus_add_pec(u16 addr, u8 command, int size, - union i2c_smbus_data *data) +/* Used for write only transactions */ +static inline void i2c_smbus_add_pec(struct i2c_msg *msg) { - u8 buf[3]; - - buf[0] = addr << 1; - buf[1] = command; - switch(size) { - case I2C_SMBUS_BYTE: - data->byte = i2c_smbus_pec(2, buf, NULL); - size = I2C_SMBUS_BYTE_DATA; - break; - case I2C_SMBUS_BYTE_DATA: - buf[2] = data->byte; - data->word = buf[2] | - (i2c_smbus_pec(3, buf, NULL) << 8); - size = I2C_SMBUS_WORD_DATA; - break; - case I2C_SMBUS_WORD_DATA: - /* unsupported */ - break; - case I2C_SMBUS_BLOCK_DATA: - data->block[data->block[0] + 1] = - i2c_smbus_pec(2, buf, data->block); - size = I2C_SMBUS_BLOCK_DATA_PEC; - break; - } - return size; + msg->buf[msg->len] = i2c_smbus_msg_pec(0, msg); + msg->len++; } -static int i2c_smbus_check_pec(u16 addr, u8 command, int size, u8 partial, - union i2c_smbus_data *data) +/* Return <0 on CRC error + If there was a write before this read (most cases) we need to take the + partial CRC from the write part into account. + Note that this function does modify the message (we need to decrease the + message length to hide the CRC byte from the caller). */ +static int i2c_smbus_check_pec(u8 cpec, struct i2c_msg *msg) { - u8 buf[3], rpec, cpec; + u8 rpec = msg->buf[--msg->len]; + cpec = i2c_smbus_msg_pec(cpec, msg); - buf[1] = command; - switch(size) { - case I2C_SMBUS_BYTE_DATA: - buf[0] = (addr << 1) | 1; - cpec = i2c_smbus_pec(2, buf, NULL); - rpec = data->byte; - break; - case I2C_SMBUS_WORD_DATA: - buf[0] = (addr << 1) | 1; - buf[2] = data->word & 0xff; - cpec = i2c_smbus_pec(3, buf, NULL); - rpec = data->word >> 8; - break; - case I2C_SMBUS_WORD_DATA_PEC: - /* unsupported */ - cpec = rpec = 0; - break; - case I2C_SMBUS_PROC_CALL_PEC: - /* unsupported */ - cpec = rpec = 0; - break; - case I2C_SMBUS_BLOCK_DATA_PEC: - buf[0] = (addr << 1); - buf[2] = (addr << 1) | 1; - cpec = i2c_smbus_pec(3, buf, data->block); - rpec = data->block[data->block[0] + 1]; - break; - case I2C_SMBUS_BLOCK_PROC_CALL_PEC: - buf[0] = (addr << 1) | 1; - rpec = i2c_smbus_partial_pec(partial, 1, - buf, data->block); - cpec = data->block[data->block[0] + 1]; - break; - default: - cpec = rpec = 0; - break; - } if (rpec != cpec) { pr_debug("i2c-core: Bad PEC 0x%02x vs. 0x%02x\n", rpec, cpec); @@ -951,9 +895,8 @@ s32 i2c_smbus_read_byte(struct i2c_client *client) s32 i2c_smbus_write_byte(struct i2c_client *client, u8 value) { - union i2c_smbus_data data; /* only for PEC */ return i2c_smbus_xfer(client->adapter,client->addr,client->flags, - I2C_SMBUS_WRITE,value, I2C_SMBUS_BYTE,&data); + I2C_SMBUS_WRITE, value, I2C_SMBUS_BYTE, NULL); } s32 i2c_smbus_read_byte_data(struct i2c_client *client, u8 command) @@ -1043,6 +986,7 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter * adapter, u16 addr, { addr, flags | I2C_M_RD, 0, msgbuf1 } }; int i; + u8 partial_pec = 0; msgbuf0[0] = command; switch(size) { @@ -1085,7 +1029,6 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter * adapter, u16 addr, msgbuf0[2] = (data->word >> 8) & 0xff; break; case I2C_SMBUS_BLOCK_DATA: - case I2C_SMBUS_BLOCK_DATA_PEC: if (read_write == I2C_SMBUS_READ) { dev_err(&adapter->dev, "Block read not supported " "under I2C emulation!\n"); @@ -1098,14 +1041,11 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter * adapter, u16 addr, data->block[0]); return -1; } - if(size == I2C_SMBUS_BLOCK_DATA_PEC) - (msg[0].len)++; for (i = 1; i < msg[0].len; i++) msgbuf0[i] = data->block[i-1]; } break; case I2C_SMBUS_BLOCK_PROC_CALL: - case I2C_SMBUS_BLOCK_PROC_CALL_PEC: dev_dbg(&adapter->dev, "Block process call not supported " "under I2C emulation!\n"); return -1; @@ -1130,9 +1070,30 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter * adapter, u16 addr, return -1; } + i = ((flags & I2C_CLIENT_PEC) && size != I2C_SMBUS_QUICK + && size != I2C_SMBUS_I2C_BLOCK_DATA); + if (i) { + /* Compute PEC if first message is a write */ + if (!(msg[0].flags & I2C_M_RD)) { + if (num == 1) /* Write only */ + i2c_smbus_add_pec(&msg[0]); + else /* Write followed by read */ + partial_pec = i2c_smbus_msg_pec(0, &msg[0]); + } + /* Ask for PEC if last message is a read */ + if (msg[num-1].flags & I2C_M_RD) + msg[num-1].len++; + } + if (i2c_transfer(adapter, msg, num) < 0) return -1; + /* Check PEC if last message is a read */ + if (i && (msg[num-1].flags & I2C_M_RD)) { + if (i2c_smbus_check_pec(partial_pec, &msg[num-1]) < 0) + return -1; + } + if (read_write == I2C_SMBUS_READ) switch(size) { case I2C_SMBUS_BYTE: @@ -1161,28 +1122,8 @@ s32 i2c_smbus_xfer(struct i2c_adapter * adapter, u16 addr, unsigned short flags, union i2c_smbus_data * data) { s32 res; - int swpec = 0; - u8 partial = 0; flags &= I2C_M_TEN | I2C_CLIENT_PEC; - if((flags & I2C_CLIENT_PEC) && - !(i2c_check_functionality(adapter, I2C_FUNC_SMBUS_HWPEC_CALC))) { - swpec = 1; - if(read_write == I2C_SMBUS_READ && - size == I2C_SMBUS_BLOCK_DATA) - size = I2C_SMBUS_BLOCK_DATA_PEC; - else if(size == I2C_SMBUS_PROC_CALL) - size = I2C_SMBUS_PROC_CALL_PEC; - else if(size == I2C_SMBUS_BLOCK_PROC_CALL) { - i2c_smbus_add_pec(addr, command, - I2C_SMBUS_BLOCK_DATA, data); - partial = data->block[data->block[0] + 1]; - size = I2C_SMBUS_BLOCK_PROC_CALL_PEC; - } else if(read_write == I2C_SMBUS_WRITE && - size != I2C_SMBUS_QUICK && - size != I2C_SMBUS_I2C_BLOCK_DATA) - size = i2c_smbus_add_pec(addr, command, size, data); - } if (adapter->algo->smbus_xfer) { down(&adapter->bus_lock); @@ -1193,13 +1134,6 @@ s32 i2c_smbus_xfer(struct i2c_adapter * adapter, u16 addr, unsigned short flags, res = i2c_smbus_xfer_emulated(adapter,addr,flags,read_write, command,size,data); - if(res >= 0 && swpec && - size != I2C_SMBUS_QUICK && size != I2C_SMBUS_I2C_BLOCK_DATA && - (read_write == I2C_SMBUS_READ || size == I2C_SMBUS_PROC_CALL_PEC || - size == I2C_SMBUS_BLOCK_PROC_CALL_PEC)) { - if(i2c_smbus_check_pec(addr, command, size, partial, data)) - return -1; - } return res; } diff --git a/include/linux/i2c.h b/include/linux/i2c.h index bcd4bb1b450c..78c64f7b3105 100644 --- a/include/linux/i2c.h +++ b/include/linux/i2c.h @@ -434,7 +434,7 @@ union i2c_smbus_data { __u8 byte; __u16 word; __u8 block[I2C_SMBUS_BLOCK_MAX + 2]; /* block[0] is used for length */ - /* and one more for PEC */ + /* and one more for user-space compatibility */ }; /* smbus_access read or write markers */