As the bus driver side implementation of I2C_M_RECV_LEN is heavily
tied to SMBus, we can't support received length over 32 bytes, but
let's at least support that.
In practice, the caller will have to setup a buffer large enough to
cover the case where received length byte has value 32, so minimum
32 + 1 = 33 bytes, possibly more if there is a fixed number of bytes
added for the specific slave (for example a checksum.)
Signed-off-by: Jean Delvare <khali@xxxxxxxxxxxx>
Cc: Douglas Gilbert <dgilbert@xxxxxxxxxxxx>
---
This is an alternative to Doug's implementation. Doug, I sent this to
you one week ago, did you have the time to give it a try, do you have
any comment? Again I can't test this myself so someone else will have
to do it.
drivers/i2c/i2c-dev.c | 19 +++++++++++++++----
1 file changed, 15 insertions(+), 4 deletions(-)
--- linux-3.3-rc7.orig/drivers/i2c/i2c-dev.c 2012-03-15 18:00:02.502988008 +0100
+++ linux-3.3-rc7/drivers/i2c/i2c-dev.c 2012-03-15 18:04:46.394992216 +0100
@@ -265,19 +265,30 @@ static noinline int i2cdev_ioctl_rdrw(st
res = 0;
for (i = 0; i < rdwr_arg.nmsgs; i++) {
- /* Limit the size of the message to a sane amount;
- * and don't let length change either. */
- if ((rdwr_pa[i].len > 8192) ||
- (rdwr_pa[i].flags & I2C_M_RECV_LEN)) {
+ /* Limit the size of the message to a sane amount */
+ if (rdwr_pa[i].len > 8192) {
res = -EINVAL;
break;
}
+
+ /* Use the same RECV_LEN semantics as SMBus */
+ if (rdwr_pa[i].flags & I2C_M_RECV_LEN) {
+ if (rdwr_pa[i].len < I2C_SMBUS_BLOCK_MAX + 1) {
+ res = -EINVAL;
+ break;
+ }
+ }
+
data_ptrs[i] = (u8 __user *)rdwr_pa[i].buf;
rdwr_pa[i].buf = memdup_user(data_ptrs[i], rdwr_pa[i].len);
if (IS_ERR(rdwr_pa[i].buf)) {
res = PTR_ERR(rdwr_pa[i].buf);
break;
}
+
+ /* Bus driver will add the value of the first byte received */
+ if (rdwr_pa[i].flags & I2C_M_RECV_LEN)
+ rdwr_pa[i].len -= I2C_SMBUS_BLOCK_MAX;
}
if (res < 0) {
int j;
--
Jean Delvare
--
To unsubscribe from this list: send the line "unsubscribe linux-i2c" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
