Re: [PATCH v2 2/2] i2c: qup: support SMBus block read

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Hi Sricharan,


On 5/18/2016 1:06 AM, Sricharan wrote:
Hi,

<snip..>

+static bool qup_i2c_check_msg_len(struct i2c_msg *msg) {
+	return ((msg->flags & I2C_M_RD) && (msg->flags &
I2C_M_RECV_LEN)); }
+
+static int qup_i2c_set_tags_smb(u16 addr, u8 *tags, struct qup_i2c_dev
*qup,
+			struct i2c_msg *msg)
+{
+	int len = 0;
+	int data_len = qup_i2c_get_data_len(qup);
+
+	if (msg->len > 1) {
+		tags[len++] = QUP_TAG_V2_DATARD_STOP;
+		tags[len++] = data_len - 1;
+	} else {
     So we hit this else part for msg->len = 1 and this case blk.pos = 0
     will always be true right ?
Yes, will fix that in V3.

+		if (qup->blk.pos == 0) {
+			tags[len++] = QUP_TAG_V2_START;
+			tags[len++] = addr & 0xff;
+
+			if (msg->flags & I2C_M_TEN)
+				tags[len++] = addr >> 8;
+		}
+
+		tags[len++] = QUP_TAG_V2_DATARD;
+		/* 0 implies 256 bytes */
+		if (data_len == QUP_READ_LIMIT)
+			tags[len++] = 0;
+		else
+			tags[len++] = data_len;
+	}
        Even data_len will always be '1' right ?
Yes, but here preferably we use a variable than a number without a context.
+	return len;
+}
+
  static int qup_i2c_set_tags(u8 *tags, struct qup_i2c_dev *qup,
  			    struct i2c_msg *msg,  int is_dma)  { @@ -526,6
+559,10 @@ static int qup_i2c_set_tags(u8 *tags, struct qup_i2c_dev *qup,

  	int last = (qup->blk.pos == (qup->blk.count - 1)) && (qup->is_last);

+	/* Handle tags for SMBus block read */
+	if (qup_i2c_check_msg_len(msg))
+		return qup_i2c_set_tags_smb(addr, tags, qup, msg);
+
  	if (qup->blk.pos == 0) {
  		tags[len++] = QUP_TAG_V2_START;
  		tags[len++] = addr & 0xff;
@@ -1065,9 +1102,17 @@ static int qup_i2c_read_fifo_v2(struct
qup_i2c_dev *qup,
  				struct i2c_msg *msg)
  {
  	u32 val;
-	int idx, pos = 0, ret = 0, total;
+	int idx, pos = 0, ret = 0, total, msg_offset = 0;

+	/*
+	 * If the message length is already read in
+	 * the first byte of the buffer, account for
+	 * that by setting the offset
+	 */
+	if (qup_i2c_check_msg_len(msg) && (msg->len > 1))
+		msg_offset = 1;
  	total = qup_i2c_get_data_len(qup);
+	total -= msg_offset;

  	/* 2 extra bytes for read tags */
  	while (pos < (total + 2)) {
@@ -1087,8 +1132,8 @@ static int qup_i2c_read_fifo_v2(struct
qup_i2c_dev *qup,

  			if (pos >= (total + 2))
  				goto out;
-
-			msg->buf[qup->pos++] = val & 0xff;
+			msg->buf[qup->pos+msg_offset] = val & 0xff;
	A space around '+' ?
Thanks, will fix that.

+			qup->pos++;
  		}
  	}

@@ -1128,6 +1173,22 @@ static int qup_i2c_read_one_v2(struct
qup_i2c_dev *qup, struct i2c_msg *msg)
  			goto err;

  		qup->blk.pos++;
+
+		/* Handle SMBus block read length */
+		if (qup_i2c_check_msg_len(msg) && (msg->len == 1)) {
+			if (msg->buf[0] > I2C_SMBUS_BLOCK_MAX) {
+				ret = -EPROTO;
+				goto err;
+			}
+			msg->len += msg->buf[0];
+			qup->pos = 0;
+			qup_i2c_set_read_mode_v2(qup, msg->len);
+			qup_i2c_issue_xfer_v2(qup, msg);
+			ret = qup_i2c_wait_for_complete(qup, msg);
+			if (ret)
+				goto err;
		Is the issue_xfer_v2 needed inside this here ?
No, qup_i2c_issue_xfer_v2 is needed so that we read rest of the data that is indicated by the length we read earlier.

+			qup_i2c_set_blk_data(qup, msg);
+		}
  	} while (qup->blk.pos < qup->blk.count);
    Regards,
      Sricharan

Thanks,
Naveen


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