i2c: xlp9xx: Handle I2C_M_RECV_LEN in msg->flags

The driver needs to handle the flag I2C_M_RECV_LEN during receive to
support SMBus emulation.

Update receive logic to handle the case where the length is received
as the first byte of a transaction.

Also update the code to handle I2C_CLIENT_PEC, which is set when the
client sends a packet error checking code byte.

Signed-off-by: Jayachandran C <jnair@caviumnetworks.com>
Signed-off-by: Kamlakant Patel <kamlakant.patel@cavium.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

diff --git a/drivers/i2c/busses/i2c-xlp9xx.c b/drivers/i2c/busses/i2c-xlp9xx.c
index f0bef2d..b970bf8 100644 (file)
--- a/drivers/i2c/busses/i2c-xlp9xx.c
+++ b/drivers/i2c/busses/i2c-xlp9xx.c
@@ -82,6 +82,8 @@ struct xlp9xx_i2c_dev {
        struct completion msg_complete;
        int irq;
        bool msg_read;
+       bool len_recv;
+       bool client_pec;
        u32 __iomem *base;
        u32 msg_buf_remaining;
        u32 msg_len;
@@ -143,10 +145,25 @@ static void xlp9xx_i2c_fill_tx_fifo(struct xlp9xx_i2c_dev *priv)
 static void xlp9xx_i2c_drain_rx_fifo(struct xlp9xx_i2c_dev *priv)
 {
        u32 len, i;
-       u8 *buf = priv->msg_buf;
+       u8 rlen, *buf = priv->msg_buf;
 
        len = xlp9xx_read_i2c_reg(priv, XLP9XX_I2C_FIFOWCNT) &
                                  XLP9XX_I2C_FIFO_WCNT_MASK;
+       if (!len)
+               return;
+       if (priv->len_recv) {
+               /* read length byte */
+               rlen = xlp9xx_read_i2c_reg(priv, XLP9XX_I2C_MRXFIFO);
+               *buf++ = rlen;
+               len--;
+               if (priv->client_pec)
+                       ++rlen;
+               /* update remaining bytes and message length */
+               priv->msg_buf_remaining = rlen;
+               priv->msg_len = rlen + 1;
+               priv->len_recv = false;
+       }
+
        len = min(priv->msg_buf_remaining, len);
        for (i = 0; i < len; i++, buf++)
                *buf = xlp9xx_read_i2c_reg(priv, XLP9XX_I2C_MRXFIFO);
@@ -230,7 +247,7 @@ static int xlp9xx_i2c_xfer_msg(struct xlp9xx_i2c_dev *priv, struct i2c_msg *msg,
                               int last_msg)
 {
        unsigned long timeleft;
-       u32 intr_mask, cmd, val;
+       u32 intr_mask, cmd, val, len;
 
        priv->msg_buf = msg->buf;
        priv->msg_buf_remaining = priv->msg_len = msg->len;
@@ -263,9 +280,13 @@ static int xlp9xx_i2c_xfer_msg(struct xlp9xx_i2c_dev *priv, struct i2c_msg *msg,
        else
                val &= ~XLP9XX_I2C_CTRL_ADDMODE;
 
+       priv->len_recv = msg->flags & I2C_M_RECV_LEN;
+       len = priv->len_recv ? XLP9XX_I2C_FIFO_SIZE : msg->len;
+       priv->client_pec = msg->flags & I2C_CLIENT_PEC;
+
        /* set data length to be transferred */
        val = (val & ~XLP9XX_I2C_CTRL_MCTLEN_MASK) |
-             (msg->len << XLP9XX_I2C_CTRL_MCTLEN_SHIFT);
+             (len << XLP9XX_I2C_CTRL_MCTLEN_SHIFT);
        xlp9xx_write_i2c_reg(priv, XLP9XX_I2C_CTRL, val);
 
        /* fill fifo during tx */
@@ -312,6 +333,9 @@ static int xlp9xx_i2c_xfer_msg(struct xlp9xx_i2c_dev *priv, struct i2c_msg *msg,
                return -ETIMEDOUT;
        }
 
+       /* update msg->len with actual received length */
+       if (msg->flags & I2C_M_RECV_LEN)
+               msg->len = priv->msg_len;
        return 0;
 }