summaryrefslogtreecommitdiff
path: root/drivers/i2c/i2c-core.c
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/i2c/i2c-core.c')
-rw-r--r--drivers/i2c/i2c-core.c162
1 files changed, 48 insertions, 114 deletions
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 0040981..02e335a 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -19,7 +19,8 @@
/* With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi>.
All SMBus-related things are written by Frodo Looijaard <frodol@dds.nl>
- SMBus 2.0 support by Mark Studebaker <mdsxyz123@yahoo.com> */
+ SMBus 2.0 support by Mark Studebaker <mdsxyz123@yahoo.com> and
+ Jean Delvare <khali@linux-fr.org> */
#include <linux/module.h>
#include <linux/kernel.h>
@@ -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;
}
generated by cgit v0.10.2 at 2024-11-10 13:17:03 (GMT)