i2c: tegra: Add SMBus block read function

Emulate SMBus block read using ContinueXfer to read the length byte

Signed-off-by: Akhil R <akhilrajeev@nvidia.com>
Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
index 03cea10..2941e42 100644 (file)
--- 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;
 }