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 <[email protected]> Cc: Douglas Gilbert <[email protected]> --- 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 [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
