10.02.2022 18:36, Akhil R пишет:
> Emulate SMBus block read using ContinueXfer to read the length byte
>
> Signed-off-by: Akhil R <akhilrajeev@xxxxxxxxxx>
> ---
> drivers/i2c/busses/i2c-tegra.c | 18 ++++++++++++++++--
> 1 file changed, 16 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
> index 03cea102ab76..2941e42aa6a0 100644
> --- a/drivers/i2c/busses/i2c-tegra.c
> +++ b/drivers/i2c/busses/i2c-tegra.c
> @@ -1233,6 +1233,11 @@ static int tegra_i2c_xfer_msg(struct tegra_i2c_dev *i2c_dev,
> return err;
>
> i2c_dev->msg_buf = msg->buf;
> +
> + /* The condition true implies smbus block read and len is already read */
> + if (msg->flags & I2C_M_RECV_LEN && end_state != MSG_END_CONTINUE)
> + i2c_dev->msg_buf = msg->buf + 1;
> +
> i2c_dev->msg_buf_remaining = msg->len;
> i2c_dev->msg_err = I2C_ERR_NONE;
> i2c_dev->msg_read = !!(msg->flags & I2C_M_RD);
> @@ -1389,6 +1394,15 @@ static int tegra_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
> else
> end_type = MSG_END_REPEAT_START;
> }
> + /* If M_RECV_LEN use ContinueXfer to read the first byte */
> + if (msgs[i].flags & I2C_M_RECV_LEN) {
> + ret = tegra_i2c_xfer_msg(i2c_dev, &msgs[i], MSG_END_CONTINUE);
> + if (ret)
> + break;
> + /* Set the read byte as msg len */
> + msgs[i].len = msgs[i].buf[0];
> + dev_dbg(i2c_dev->dev, "reading %d bytes\n", msgs[i].len);
> + }
> ret = tegra_i2c_xfer_msg(i2c_dev, &msgs[i], end_type);
> if (ret)
> break;
> @@ -1416,10 +1430,10 @@ static u32 tegra_i2c_func(struct i2c_adapter *adap)
> {
> struct tegra_i2c_dev *i2c_dev = i2c_get_adapdata(adap);
> u32 ret = I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK) |
> - I2C_FUNC_10BIT_ADDR | I2C_FUNC_PROTOCOL_MANGLING;
> + I2C_FUNC_10BIT_ADDR | I2C_FUNC_PROTOCOL_MANGLING;
>
> if (i2c_dev->hw->has_continue_xfer_support)
> - ret |= I2C_FUNC_NOSTART;
> + ret |= I2C_FUNC_NOSTART | I2C_FUNC_SMBUS_READ_BLOCK_DATA;
>
> return ret;
> }
Please describe how this was tested.
