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

[Naveen Kaje]

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