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SubjectRe: [PATCH 2/2] i2c: qup: support SMBus block read
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On 5/10/2016 1:13 AM, Sricharan wrote:
> +additional lists
>
>> 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@codeaurora.org>
>> ---
>> drivers/i2c/busses/i2c-qup.c | 95 ++++++++++++++++++++++++++++++-------
>> -------
>> 1 file changed, 66 insertions(+), 29 deletions(-)
>>
>> diff --git a/drivers/i2c/busses/i2c-qup.c b/drivers/i2c/busses/i2c-qup.c
> index
>> ef31b26..2658b67 100644
>> --- a/drivers/i2c/busses/i2c-qup.c
>> +++ b/drivers/i2c/busses/i2c-qup.c
>> @@ -526,38 +526,49 @@ 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);
>>
>> - if (qup->blk.pos == 0) {
>> - tags[len++] = QUP_TAG_V2_START;
>> - tags[len++] = addr & 0xff;
>> + /* Handle SMBus block data read */
>> + if ((msg->flags & I2C_M_RD) && (msg->flags & I2C_M_RECV_LEN)
>> &&
>> + (msg->len > 1)) {
>> + tags[len++] = QUP_TAG_V2_DATARD_STOP;
>> + data_len = qup_i2c_get_data_len(qup);
>> + tags[len++] = data_len - 1;
>> + } else {
>> + 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;
>> - }
>> + if (msg->flags & I2C_M_TEN)
>> + tags[len++] = addr >> 8;
>> + }
>>
>> - /* Send _STOP commands for the last block */
>> - if (last) {
>> - if (msg->flags & I2C_M_RD)
>> - tags[len++] = QUP_TAG_V2_DATARD_STOP;
>> - else
>> - tags[len++] = QUP_TAG_V2_DATAWR_STOP;
>> - } else {
>> - if (msg->flags & I2C_M_RD)
>> + /* Send _STOP commands for the last block */
>> + if ((msg->flags & I2C_M_RD)
>> + && (msg->flags & I2C_M_RECV_LEN)) {
>> tags[len++] = QUP_TAG_V2_DATARD;
>> - else
>> - tags[len++] = QUP_TAG_V2_DATAWR;
>> - }
>> + } else if (last) {
>> + if (msg->flags & I2C_M_RD)
>> + tags[len++] = QUP_TAG_V2_DATARD_STOP;
>> + else
>> + tags[len++] = QUP_TAG_V2_DATAWR_STOP;
>> + } else {
>> + if (msg->flags & I2C_M_RD)
>> + tags[len++] = QUP_TAG_V2_DATARD;
>> + else
>> + tags[len++] = QUP_TAG_V2_DATAWR;
>> + }
>>
>> - data_len = qup_i2c_get_data_len(qup);
>> + data_len = qup_i2c_get_data_len(qup);
>>
>> - /* 0 implies 256 bytes */
>> - if (data_len == QUP_READ_LIMIT)
>> - tags[len++] = 0;
>> - else
>> - tags[len++] = data_len;
>> + /* 0 implies 256 bytes */
>> + if (data_len == QUP_READ_LIMIT)
>> + tags[len++] = 0;
>> + else
>> + tags[len++] = data_len;
>>
>> - if ((msg->flags & I2C_M_RD) && last && is_dma) {
>> - tags[len++] = QUP_BAM_INPUT_EOT;
>> - tags[len++] = QUP_BAM_FLUSH_STOP;
>> + if ((msg->flags & I2C_M_RD) && last && is_dma) {
>> + tags[len++] = QUP_BAM_INPUT_EOT;
>> + tags[len++] = QUP_BAM_FLUSH_STOP;
>> + }
>> }
>>
> Will it look simpler if we add a qup_i2c_set_tags_smb instead and add an
> Comment ? Here it is not clear how this is different from a normal read.
Will rework this and send V2.
> <snip..>
>
>> +
>> + /* Handle SMBus block read length */
>> + if ((msg->flags & I2C_M_RECV_LEN) && (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;
>> + qup_i2c_set_blk_data(qup, msg);
>> + }
>> } while (qup->blk.pos < qup->blk.count);
>
> When v2 mode is not supported this should return an error,
> in qup_i2c_xfer for msg->flags & I2C_M_RECV_LEN
Will add a check in qup_i2c_xfer in the next version of the patch.
>
> Regards,
> Sricharan
>

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