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Message-ID: <CAA7nrtgAh6EDJO_qTgMawE=tpZe6F_Ae1G0OhuUME0QF4W5AJA@mail.gmail.com>
Date: Wed, 25 May 2016 15:01:29 +0530
From: rajeev kumar <rajeevkumar.linux@...il.com>
To: Austin Christ <austinwc@...eaurora.org>
Cc: nkaje@...eaurora.org, Wolfram Sang <wsa@...-dreams.de>,
linux-i2c@...r.kernel.org,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
linux-arm-msm@...r.kernel.org, rruigrok@...eaurora.org,
timur@...eaurora.org, cov@...eaurora.org,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v3 2/2] i2c: qup: support SMBus block read
On Fri, May 20, 2016 at 3:14 AM, Austin Christ <austinwc@...eaurora.org> wrote:
> From: Naveen Kaje <nkaje@...eaurora.org>
>
> 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@...eaurora.org>
> Signed-off-by: Austin Christ <austinwc@...eaurora.org>
> ---
> 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;
Could you please rethink on this return value ? It should not be "EOPNOTSUPP"
~Rajeev
> + goto out;
> + }
> +
> if (msgs[idx].flags & I2C_M_RD)
> ret = qup_i2c_read_one(qup, &msgs[idx]);
> else
> --
> Qualcomm Innovation Center, Inc.
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project.
>
> --
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