Hi Wolfram,
Did you get a chance to review this patch.
Best regards,
Rayagonda
On Mon, Sep 30, 2019 at 12:19 PM Rayagonda Kokatanur
<rayagonda.kokatanur@xxxxxxxxxxxx> wrote:
>
> From: Lori Hikichi <lori.hikichi@xxxxxxxxxxxx>
>
> Enable handling of i2c repeated start. The current code
> handles a multi msg i2c transfer as separate i2c bus
> transactions. This change will now handle this case
> using the i2c repeated start protocol. The number of msgs
> in a transfer is limited to two, and must be a write
> followed by a read.
>
> Signed-off-by: Lori Hikichi <lori.hikichi@xxxxxxxxxxxx>
> Signed-off-by: Rayagonda Kokatanur <rayagonda.kokatanur@xxxxxxxxxxxx>
> Signed-off-by: Icarus Chau <icarus.chau@xxxxxxxxxxxx>
> Signed-off-by: Ray Jui <ray.jui@xxxxxxxxxxxx>
> Signed-off-by: Shivaraj Shetty <sshetty1@xxxxxxxxxxxx>
> ---
> changes from v1:
> - Address following review comments from Wolfarm Sang,
> Use i2c_8bit_addr_from_msg() api instead of decoding i2c_msg struct and
> remove check against number of i2c message as it will be taken care
> by core using quirks flags.
>
> drivers/i2c/busses/i2c-bcm-iproc.c | 63 ++++++++++++++++++++++++++++++--------
> 1 file changed, 50 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-bcm-iproc.c b/drivers/i2c/busses/i2c-bcm-iproc.c
> index d7fd76b..e478db7 100644
> --- a/drivers/i2c/busses/i2c-bcm-iproc.c
> +++ b/drivers/i2c/busses/i2c-bcm-iproc.c
> @@ -81,6 +81,7 @@
> #define M_CMD_PROTOCOL_MASK 0xf
> #define M_CMD_PROTOCOL_BLK_WR 0x7
> #define M_CMD_PROTOCOL_BLK_RD 0x8
> +#define M_CMD_PROTOCOL_PROCESS 0xa
> #define M_CMD_PEC_SHIFT 8
> #define M_CMD_RD_CNT_SHIFT 0
> #define M_CMD_RD_CNT_MASK 0xff
> @@ -675,13 +676,20 @@ static int bcm_iproc_i2c_xfer_wait(struct bcm_iproc_i2c_dev *iproc_i2c,
> return 0;
> }
>
> -static int bcm_iproc_i2c_xfer_single_msg(struct bcm_iproc_i2c_dev *iproc_i2c,
> - struct i2c_msg *msg)
> +/*
> + * If 'process_call' is true, then this is a multi-msg transfer that requires
> + * a repeated start between the messages.
> + * More specifically, it must be a write (reg) followed by a read (data).
> + * The i2c quirks are set to enforce this rule.
> + */
> +static int bcm_iproc_i2c_xfer_internal(struct bcm_iproc_i2c_dev *iproc_i2c,
> + struct i2c_msg *msgs, bool process_call)
> {
> int i;
> u8 addr;
> u32 val, tmp, val_intr_en;
> unsigned int tx_bytes;
> + struct i2c_msg *msg = &msgs[0];
>
> /* check if bus is busy */
> if (!!(iproc_i2c_rd_reg(iproc_i2c,
> @@ -707,14 +715,29 @@ static int bcm_iproc_i2c_xfer_single_msg(struct bcm_iproc_i2c_dev *iproc_i2c,
> val = msg->buf[i];
>
> /* mark the last byte */
> - if (i == msg->len - 1)
> - val |= BIT(M_TX_WR_STATUS_SHIFT);
> + if (!process_call && (i == msg->len - 1))
> + val |= 1 << M_TX_WR_STATUS_SHIFT;
>
> iproc_i2c_wr_reg(iproc_i2c, M_TX_OFFSET, val);
> }
> iproc_i2c->tx_bytes = tx_bytes;
> }
>
> + /* Process the read message if this is process call */
> + if (process_call) {
> + msg++;
> + iproc_i2c->msg = msg; /* point to second msg */
> +
> + /*
> + * The last byte to be sent out should be a slave
> + * address with read operation
> + */
> + addr = i2c_8bit_addr_from_msg(msg);
> + /* mark it the last byte out */
> + val = addr | (1 << M_TX_WR_STATUS_SHIFT);
> + iproc_i2c_wr_reg(iproc_i2c, M_TX_OFFSET, val);
> + }
> +
> /* mark as incomplete before starting the transaction */
> if (iproc_i2c->irq)
> reinit_completion(&iproc_i2c->done);
> @@ -733,7 +756,7 @@ static int bcm_iproc_i2c_xfer_single_msg(struct bcm_iproc_i2c_dev *iproc_i2c,
> * underrun interrupt, which will be triggerred when the TX FIFO is
> * empty. When that happens we can then pump more data into the FIFO
> */
> - if (!(msg->flags & I2C_M_RD) &&
> + if (!process_call && !(msg->flags & I2C_M_RD) &&
> msg->len > iproc_i2c->tx_bytes)
> val_intr_en |= BIT(IE_M_TX_UNDERRUN_SHIFT);
>
> @@ -743,6 +766,8 @@ static int bcm_iproc_i2c_xfer_single_msg(struct bcm_iproc_i2c_dev *iproc_i2c,
> */
> val = BIT(M_CMD_START_BUSY_SHIFT);
> if (msg->flags & I2C_M_RD) {
> + u32 protocol;
> +
> iproc_i2c->rx_bytes = 0;
> if (msg->len > M_RX_FIFO_MAX_THLD_VALUE)
> iproc_i2c->thld_bytes = M_RX_FIFO_THLD_VALUE;
> @@ -758,7 +783,10 @@ static int bcm_iproc_i2c_xfer_single_msg(struct bcm_iproc_i2c_dev *iproc_i2c,
> /* enable the RX threshold interrupt */
> val_intr_en |= BIT(IE_M_RX_THLD_SHIFT);
>
> - val |= (M_CMD_PROTOCOL_BLK_RD << M_CMD_PROTOCOL_SHIFT) |
> + protocol = process_call ?
> + M_CMD_PROTOCOL_PROCESS : M_CMD_PROTOCOL_BLK_RD;
> +
> + val |= (protocol << M_CMD_PROTOCOL_SHIFT) |
> (msg->len << M_CMD_RD_CNT_SHIFT);
> } else {
> val |= (M_CMD_PROTOCOL_BLK_WR << M_CMD_PROTOCOL_SHIFT);
> @@ -774,17 +802,24 @@ static int bcm_iproc_i2c_xfer(struct i2c_adapter *adapter,
> struct i2c_msg msgs[], int num)
> {
> struct bcm_iproc_i2c_dev *iproc_i2c = i2c_get_adapdata(adapter);
> - int ret, i;
> + bool process_call = false;
> + int ret;
>
> - /* go through all messages */
> - for (i = 0; i < num; i++) {
> - ret = bcm_iproc_i2c_xfer_single_msg(iproc_i2c, &msgs[i]);
> - if (ret) {
> - dev_dbg(iproc_i2c->device, "xfer failed\n");
> - return ret;
> + if (num == 2) {
> + /* Repeated start, use process call */
> + process_call = true;
> + if (msgs[1].flags & I2C_M_NOSTART) {
> + dev_err(iproc_i2c->device, "Invalid repeated start\n");
> + return -EOPNOTSUPP;
> }
> }
>
> + ret = bcm_iproc_i2c_xfer_internal(iproc_i2c, msgs, process_call);
> + if (ret) {
> + dev_dbg(iproc_i2c->device, "xfer failed\n");
> + return ret;
> + }
> +
> return num;
> }
>
> @@ -806,6 +841,8 @@ static uint32_t bcm_iproc_i2c_functionality(struct i2c_adapter *adap)
> };
>
> static struct i2c_adapter_quirks bcm_iproc_i2c_quirks = {
> + .flags = I2C_AQ_COMB_WRITE_THEN_READ,
> + .max_comb_1st_msg_len = M_TX_RX_FIFO_SIZE,
> .max_read_len = M_RX_MAX_READ_LEN,
> };
>
> --
> 1.9.1
>
