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From:   Rayagonda Kokatanur <rayagonda.kokatanur@broadcom.com>
Date:   Mon, 27 May 2019 08:58:45 +0530
Message-ID: <CAHO=5PFTenqnyrP0xBJ95cq0XUukzAgwF4g=xi8Rwj6HxFZD=g@mail.gmail.com>
Subject: Re: [PATCH 1/1] i2c: iproc: Add multi byte read-write support for
 slave mode
To:     Ray Jui <ray.jui@broadcom.com>, Wolfram Sang <wsa@the-dreams.de>,
        Rob Herring <robh+dt@kernel.org>, linux-i2c@vger.kernel.org
Cc:     Mark Rutland <mark.rutland@arm.com>,
        BCM Kernel Feedback <bcm-kernel-feedback-list@broadcom.com>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        Michael Cheng <ccheng@broadcom.com>,
        Srinath Mannam <srinath.mannam@broadcom.com>
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Sender: linux-kernel-owner@vger.kernel.org
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Hi All,

Please review the patch and let me know your review comments if any.

Best regards,
Rayagonda


On Wed, May 15, 2019 at 9:58 PM Rayagonda Kokatanur
<rayagonda.kokatanur@broadcom.com> wrote:
>
> No change,  it's just duplicate, please ignore first patch and review
> second patch.
>
> Best regards
> Rayagonda
>
>
>
> On Thu, May 9, 2019 at 9:58 PM Ray Jui <ray.jui@broadcom.com> wrote:
> >
> > Why is the email sent twice? What has changed?
> >
> > On 5/8/2019 9:21 PM, Rayagonda Kokatanur wrote:
> > > Add multiple byte read-write support for slave mode.
> > >
> > > Signed-off-by: Rayagonda Kokatanur <rayagonda.kokatanur@broadcom.com>
> > > Signed-off-by: Srinath Mannam <srinath.mannam@broadcom.com>
> > > ---
> > >  drivers/i2c/busses/i2c-bcm-iproc.c | 117 +++++++++++++++++--------------------
> > >  1 file changed, 53 insertions(+), 64 deletions(-)
> > >
> > > diff --git a/drivers/i2c/busses/i2c-bcm-iproc.c b/drivers/i2c/busses/i2c-bcm-iproc.c
> > > index a845b8d..2c7f145 100644
> > > --- a/drivers/i2c/busses/i2c-bcm-iproc.c
> > > +++ b/drivers/i2c/busses/i2c-bcm-iproc.c
> > > @@ -165,12 +165,6 @@ enum i2c_slave_read_status {
> > >       I2C_SLAVE_RX_END,
> > >  };
> > >
> > > -enum i2c_slave_xfer_dir {
> > > -     I2C_SLAVE_DIR_READ = 0,
> > > -     I2C_SLAVE_DIR_WRITE,
> > > -     I2C_SLAVE_DIR_NONE,
> > > -};
> > > -
> > >  enum bus_speed_index {
> > >       I2C_SPD_100K = 0,
> > >       I2C_SPD_400K,
> > > @@ -203,7 +197,6 @@ struct bcm_iproc_i2c_dev {
> > >       struct i2c_msg *msg;
> > >
> > >       struct i2c_client *slave;
> > > -     enum i2c_slave_xfer_dir xfer_dir;
> > >
> > >       /* bytes that have been transferred */
> > >       unsigned int tx_bytes;
> > > @@ -219,7 +212,8 @@ struct bcm_iproc_i2c_dev {
> > >               | BIT(IS_M_RX_THLD_SHIFT))
> > >
> > >  #define ISR_MASK_SLAVE (BIT(IS_S_START_BUSY_SHIFT)\
> > > -             | BIT(IS_S_RX_EVENT_SHIFT) | BIT(IS_S_RD_EVENT_SHIFT))
> > > +             | BIT(IS_S_RX_EVENT_SHIFT) | BIT(IS_S_RD_EVENT_SHIFT)\
> > > +             | BIT(IS_S_TX_UNDERRUN_SHIFT))
> > >
> > >  static int bcm_iproc_i2c_reg_slave(struct i2c_client *slave);
> > >  static int bcm_iproc_i2c_unreg_slave(struct i2c_client *slave);
> > > @@ -297,15 +291,11 @@ static void bcm_iproc_i2c_slave_init(
> > >       /* clear all pending slave interrupts */
> > >       iproc_i2c_wr_reg(iproc_i2c, IS_OFFSET, ISR_MASK_SLAVE);
> > >
> > > -     /* Enable interrupt register for any READ event */
> > > -     val = BIT(IE_S_RD_EVENT_SHIFT);
> > >       /* Enable interrupt register to indicate a valid byte in receive fifo */
> > > -     val |= BIT(IE_S_RX_EVENT_SHIFT);
> > > +     val = BIT(IE_S_RX_EVENT_SHIFT);
> > >       /* Enable interrupt register for the Slave BUSY command */
> > >       val |= BIT(IE_S_START_BUSY_SHIFT);
> > >       iproc_i2c_wr_reg(iproc_i2c, IE_OFFSET, val);
> > > -
> > > -     iproc_i2c->xfer_dir = I2C_SLAVE_DIR_NONE;
> > >  }
> > >
> > >  static void bcm_iproc_i2c_check_slave_status(
> > > @@ -314,8 +304,11 @@ static void bcm_iproc_i2c_check_slave_status(
> > >       u32 val;
> > >
> > >       val = iproc_i2c_rd_reg(iproc_i2c, S_CMD_OFFSET);
> > > -     val = (val >> S_CMD_STATUS_SHIFT) & S_CMD_STATUS_MASK;
> > > +     /* status is valid only when START_BUSY is cleared after it was set */
> > > +     if (val & BIT(S_CMD_START_BUSY_SHIFT))
> > > +             return;
> > >
> > > +     val = (val >> S_CMD_STATUS_SHIFT) & S_CMD_STATUS_MASK;
> > >       if (val == S_CMD_STATUS_TIMEOUT) {
> > >               dev_err(iproc_i2c->device, "slave random stretch time timeout\n");
> > >
> > > @@ -327,70 +320,66 @@ static void bcm_iproc_i2c_check_slave_status(
> > >  }
> > >
> > >  static bool bcm_iproc_i2c_slave_isr(struct bcm_iproc_i2c_dev *iproc_i2c,
> > > -                             u32 status)
> > > +                                 u32 status)
> > >  {
> > > -     u8 value;
> > >       u32 val;
> > > -     u32 rd_status;
> > > -     u32 tmp;
> > > +     u8 value, rx_status;
> > >
> > > -     /* Start of transaction. check address and populate the direction */
> > > -     if (iproc_i2c->xfer_dir == I2C_SLAVE_DIR_NONE) {
> > > -             tmp = iproc_i2c_rd_reg(iproc_i2c, S_RX_OFFSET);
> > > -             rd_status = (tmp >> S_RX_STATUS_SHIFT) & S_RX_STATUS_MASK;
> > > -             /* This condition checks whether the request is a new request */
> > > -             if (((rd_status == I2C_SLAVE_RX_START) &&
> > > -                     (status & BIT(IS_S_RX_EVENT_SHIFT))) ||
> > > -                     ((rd_status == I2C_SLAVE_RX_END) &&
> > > -                     (status & BIT(IS_S_RD_EVENT_SHIFT)))) {
> > > -
> > > -                     /* Last bit is W/R bit.
> > > -                      * If 1 then its a read request(by master).
> > > -                      */
> > > -                     iproc_i2c->xfer_dir = tmp & SLAVE_READ_WRITE_BIT_MASK;
> > > -                     if (iproc_i2c->xfer_dir == I2C_SLAVE_DIR_WRITE)
> > > -                             i2c_slave_event(iproc_i2c->slave,
> > > -                                     I2C_SLAVE_READ_REQUESTED, &value);
> > > -                     else
> > > -                             i2c_slave_event(iproc_i2c->slave,
> > > +     /* Slave RX byte receive */
> > > +     if (status & BIT(IS_S_RX_EVENT_SHIFT)) {
> > > +             val = iproc_i2c_rd_reg(iproc_i2c, S_RX_OFFSET);
> > > +             rx_status = (val >> S_RX_STATUS_SHIFT) & S_RX_STATUS_MASK;
> > > +             if (rx_status == I2C_SLAVE_RX_START) {
> > > +                     /* Start of SMBUS for Master write */
> > > +                     i2c_slave_event(iproc_i2c->slave,
> > >                                       I2C_SLAVE_WRITE_REQUESTED, &value);
> > > -             }
> > > -     }
> > >
> > > -     /* read request from master */
> > > -     if ((status & BIT(IS_S_RD_EVENT_SHIFT)) &&
> > > -             (iproc_i2c->xfer_dir == I2C_SLAVE_DIR_WRITE)) {
> > > -             i2c_slave_event(iproc_i2c->slave,
> > > -                     I2C_SLAVE_READ_PROCESSED, &value);
> > > -             iproc_i2c_wr_reg(iproc_i2c, S_TX_OFFSET, value);
> > > +                     val = iproc_i2c_rd_reg(iproc_i2c, S_RX_OFFSET);
> > > +                     value = (u8)((val >> S_RX_DATA_SHIFT) & S_RX_DATA_MASK);
> > > +                     i2c_slave_event(iproc_i2c->slave,
> > > +                                     I2C_SLAVE_WRITE_RECEIVED, &value);
> > > +             } else if (status & BIT(IS_S_RD_EVENT_SHIFT)) {
> > > +                     /* Start of SMBUS for Master Read */
> > > +                     i2c_slave_event(iproc_i2c->slave,
> > > +                                     I2C_SLAVE_READ_REQUESTED, &value);
> > > +                     iproc_i2c_wr_reg(iproc_i2c, S_TX_OFFSET, value);
> > >
> > > -             val = BIT(S_CMD_START_BUSY_SHIFT);
> > > -             iproc_i2c_wr_reg(iproc_i2c, S_CMD_OFFSET, val);
> > > -     }
> > > +                     val = BIT(S_CMD_START_BUSY_SHIFT);
> > > +                     iproc_i2c_wr_reg(iproc_i2c, S_CMD_OFFSET, val);
> > >
> > > -     /* write request from master */
> > > -     if ((status & BIT(IS_S_RX_EVENT_SHIFT)) &&
> > > -             (iproc_i2c->xfer_dir == I2C_SLAVE_DIR_READ)) {
> > > -             val = iproc_i2c_rd_reg(iproc_i2c, S_RX_OFFSET);
> > > -             /* Its a write request by Master to Slave.
> > > -              * We read data present in receive FIFO
> > > -              */
> > > -             value = (u8)((val >> S_RX_DATA_SHIFT) & S_RX_DATA_MASK);
> > > +                     /*
> > > +                      * Enable interrupt for TX FIFO becomes empty and
> > > +                      * less than PKT_LENGTH bytes were output on the SMBUS
> > > +                      */
> > > +                     val = iproc_i2c_rd_reg(iproc_i2c, IE_OFFSET);
> > > +                     val |= BIT(IE_S_TX_UNDERRUN_SHIFT);
> > > +                     iproc_i2c_wr_reg(iproc_i2c, IE_OFFSET, val);
> > > +             } else {
> > > +                     /* Master write other than start */
> > > +                     value = (u8)((val >> S_RX_DATA_SHIFT) & S_RX_DATA_MASK);
> > > +                     i2c_slave_event(iproc_i2c->slave,
> > > +                                     I2C_SLAVE_WRITE_RECEIVED, &value);
> > > +             }
> > > +     } else if (status & BIT(IS_S_TX_UNDERRUN_SHIFT)) {
> > > +             /* Master read other than start */
> > >               i2c_slave_event(iproc_i2c->slave,
> > > -                     I2C_SLAVE_WRITE_RECEIVED, &value);
> > > -
> > > -             /* check the status for the last byte of the transaction */
> > > -             rd_status = (val >> S_RX_STATUS_SHIFT) & S_RX_STATUS_MASK;
> > > -             if (rd_status == I2C_SLAVE_RX_END)
> > > -                     iproc_i2c->xfer_dir = I2C_SLAVE_DIR_NONE;
> > > +                             I2C_SLAVE_READ_PROCESSED, &value);
> > >
> > > -             dev_dbg(iproc_i2c->device, "\nread value = 0x%x\n", value);
> > > +             iproc_i2c_wr_reg(iproc_i2c, S_TX_OFFSET, value);
> > > +             val = BIT(S_CMD_START_BUSY_SHIFT);
> > > +             iproc_i2c_wr_reg(iproc_i2c, S_CMD_OFFSET, val);
> > >       }
> > >
> > >       /* Stop */
> > >       if (status & BIT(IS_S_START_BUSY_SHIFT)) {
> > >               i2c_slave_event(iproc_i2c->slave, I2C_SLAVE_STOP, &value);
> > > -             iproc_i2c->xfer_dir = I2C_SLAVE_DIR_NONE;
> > > +             /*
> > > +              * Enable interrupt for TX FIFO becomes empty and
> > > +              * less than PKT_LENGTH bytes were output on the SMBUS
> > > +              */
> > > +             val = iproc_i2c_rd_reg(iproc_i2c, IE_OFFSET);
> > > +             val &= ~BIT(IE_S_TX_UNDERRUN_SHIFT);
> > > +             iproc_i2c_wr_reg(iproc_i2c, IE_OFFSET, val);
> > >       }
> > >
> > >       /* clear interrupt status */
> > >