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i2c: dev: Handle 255 byte blocks for i2c ioctl

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I2C_SMBUS is limited to 32 bytes due to compatibility with the
32 byte i2c_smbus_data.block

I2C_RDWR allows larger transfers if sufficient sized buffers are passed.

Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Matt Johnston 2021-11-15 10:49:22 +08:00 • committed by David S. Miller
parent 13cae4a104
commit 84a107e68b
3 changed files with 83 additions and 14 deletions
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2
include/uapi/linux/i2c-dev.h
View file

@ -39,12 +39,14 @@
/* This is the structure as used in the I2C_SMBUS ioctl call */
#ifndef __KERNEL__
struct i2c_smbus_ioctl_data {
__u8 read_write;
__u8 command;
__u32 size;
union i2c_smbus_data __user *data;
};
#endif
/* This is the structure as used in the I2C_RDWR ioctl call */
struct i2c_rdwr_ioctl_data {

2
include/uapi/linux/i2c.h
View file

@ -109,6 +109,8 @@ struct i2c_msg {
#define I2C_FUNC_SMBUS_WRITE_I2C_BLOCK 0x08000000 /* w/ 1-byte reg. addr. */
#define I2C_FUNC_SMBUS_HOST_NOTIFY 0x10000000 /* SMBus 2.0 or later */
#define I2C_FUNC_SMBUS_V3_BLOCK 0x20000000 /* Device supports 255 byte block */
/* Note that I2C_SMBUS ioctl only */
/* supports a 32 byte block */
#define I2C_FUNC_SMBUS_BYTE (I2C_FUNC_SMBUS_READ_BYTE | \
I2C_FUNC_SMBUS_WRITE_BYTE)