Commit 209d27c3 authored by Jean Delvare's avatar Jean Delvare Committed by Jean Delvare
Browse files

i2c: Emulate SMBus block read over I2C 



Let the I2C bus drivers emulate the SMBus Block Read and Block Process
Call transactions if they wish. This requires to define a new message
flag, which i2c-core will use to let the underlying I2C bus driver
know that the first received byte will specify the length of the read
message.

Signed-off-by: default avatarJean Delvare <khali@linux-fr.org>
parent 1ecac07a

drivers/i2c/i2c-core.c

+26 −8
Original line number Diff line number Diff line
@@ -590,8 +590,9 @@ int i2c_transfer(struct i2c_adapter * adap, struct i2c_msg *msgs, int num) 
#ifdef DEBUG

		for (ret = 0; ret < num; ret++) {

			dev_dbg(&adap->dev, "master_xfer[%d] %c, addr=0x%02x, "

				"len=%d\n", ret, msgs[ret].flags & I2C_M_RD ?

				'R' : 'W', msgs[ret].addr, msgs[ret].len);

				"len=%d%s\n", ret, (msgs[ret].flags & I2C_M_RD)

				? 'R' : 'W', msgs[ret].addr, msgs[ret].len,

				(msgs[ret].flags & I2C_M_RECV_LEN) ? "+" : "");

		}

#endif
@@ -1050,9 +1051,9 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter * adapter, u16 addr, 
		break;

	case I2C_SMBUS_BLOCK_DATA:

		if (read_write == I2C_SMBUS_READ) {

			dev_err(&adapter->dev, "Block read not supported "

			       "under I2C emulation!\n");

			return -1;

			msg[1].flags |= I2C_M_RECV_LEN;

			msg[1].len = 1; /* block length will be added by

					   the underlying bus driver */

		} else {

			msg[0].len = data->block[0] + 2;

			if (msg[0].len > I2C_SMBUS_BLOCK_MAX + 2) {
@@ -1066,9 +1067,21 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter * adapter, u16 addr, 
		}

		break;

	case I2C_SMBUS_BLOCK_PROC_CALL:

		dev_dbg(&adapter->dev, "Block process call not supported "

		       "under I2C emulation!\n");

		num = 2; /* Another special case */

		read_write = I2C_SMBUS_READ;

		if (data->block[0] > I2C_SMBUS_BLOCK_MAX) {

			dev_err(&adapter->dev, "%s called with invalid "

				"block proc call size (%d)\n", __FUNCTION__,

				data->block[0]);

			return -1;

		}

		msg[0].len = data->block[0] + 2;

		for (i = 1; i < msg[0].len; i++)

			msgbuf0[i] = data->block[i-1];

		msg[1].flags |= I2C_M_RECV_LEN;

		msg[1].len = 1; /* block length will be added by

				   the underlying bus driver */

		break;

	case I2C_SMBUS_I2C_BLOCK_DATA:

		if (read_write == I2C_SMBUS_READ) {

			msg[1].len = I2C_SMBUS_BLOCK_MAX;
@@ -1132,6 +1145,11 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter * adapter, u16 addr, 
				for (i = 0; i < I2C_SMBUS_BLOCK_MAX; i++)

					data->block[i+1] = msgbuf1[i];

				break;

			case I2C_SMBUS_BLOCK_DATA:

			case I2C_SMBUS_BLOCK_PROC_CALL:

				for (i = 0; i < msgbuf1[0] + 1; i++)

					data->block[i] = msgbuf1[i];

				break;

		}

	return 0;

}

include/linux/i2c.h

+1 −0
Original line number Diff line number Diff line
@@ -366,6 +366,7 @@ struct i2c_msg { 
#define I2C_M_REV_DIR_ADDR	0x2000

#define I2C_M_IGNORE_NAK	0x1000

#define I2C_M_NO_RD_ACK		0x0800

#define I2C_M_RECV_LEN		0x0400 /* length will be first received byte */

	__u16 len;		/* msg length				*/

	__u8 *buf;		/* pointer to msg data			*/

};

CRA Git | Maintained and supported by SUSTech CRA and CCSE