Hi,
>From: Naveen Kaje <nkaje@xxxxxxxxxxxxxx>
>
>I2C QUP driver relies on SMBus emulation support from the framework.
>To handle SMBus block reads, the driver should check I2C_M_RECV_LEN
>flag and should read the first byte received as the message length.
>
>The driver configures the QUP hardware to read one byte. Once the
>message length is known from this byte, the QUP hardware is configured
>to read the rest.
>
>Signed-off-by: Naveen Kaje <nkaje@xxxxxxxxxxxxxx>
>Signed-off-by: Austin Christ <austinwc@xxxxxxxxxxxxxx>
>---
> drivers/i2c/busses/i2c-qup.c | 68 ++++++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 65 insertions(+), 3 deletions(-)
>
>Changes:
>- v3:
> - clean up redundant checks
> - use constant instead of variable for smbus length field
>- v2:
> - rework the smbus block read and break into separate function
>
>diff --git a/drivers/i2c/busses/i2c-qup.c b/drivers/i2c/busses/i2c-qup.c
>index ea6ca5f..9fbed83 100644
>--- a/drivers/i2c/busses/i2c-qup.c
>+++ b/drivers/i2c/busses/i2c-qup.c
>@@ -517,6 +517,33 @@ static int qup_i2c_get_data_len(struct qup_i2c_dev *qup)
> return data_len;
> }
>
>+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;
>+
>+ if (msg->len > 1) {
>+ tags[len++] = QUP_TAG_V2_DATARD_STOP;
>+ tags[len++] = qup_i2c_get_data_len(qup) - 1;
>+ } else {
>+ 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;
>+ /* Read 1 byte indicating the length of the SMBus message */
>+ tags[len++] = 1;
>+ }
>+ return len;
>+}
>+
> static int qup_i2c_set_tags(u8 *tags, struct qup_i2c_dev *qup,
> struct i2c_msg *msg, int is_dma)
> {
>@@ -526,6 +553,10 @@ 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 +1096,17 @@ 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 +1126,8 @@ 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;
>+ qup->pos++;
> }
> }
>
>@@ -1128,6 +1167,24 @@ 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);
>+ ret = qup_i2c_issue_xfer_v2(qup, msg);
>+ if (ret)
>+ goto err;
>+ ret = qup_i2c_wait_for_complete(qup, msg);
>+ if (ret)
>+ goto err;
>+ qup_i2c_set_blk_data(qup, msg);
>+ }
> } while (qup->blk.pos < qup->blk.count);
>
> err:
>@@ -1210,6 +1267,11 @@ static int qup_i2c_xfer(struct i2c_adapter *adap,
> goto out;
> }
>
>+ if (qup_i2c_check_msg_len(&msgs[idx])) {
>+ ret = -EOPNOTSUPP;
>+ goto out;
>+ }
>+
> if (msgs[idx].flags & I2C_M_RD)
> ret = qup_i2c_read_one(qup, &msgs[idx]);
> else
Reviewed-by: sricharan@xxxxxxxxxxxxxx
Regards,
Sricharan
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