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Date: Mon, 27 May 2019 09:26:38 -0700
From: Ray Jui <ray.jui@...adcom.com>
To: Rayagonda Kokatanur <rayagonda.kokatanur@...adcom.com>,
Wolfram Sang <wsa@...-dreams.de>,
Rob Herring <robh+dt@...nel.org>,
Mark Rutland <mark.rutland@....com>
Cc: linux-i2c@...r.kernel.org, bcm-kernel-feedback-list@...adcom.com,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
Michael Cheng <ccheng@...adcom.com>,
Srinath Mannam <srinath.mannam@...adcom.com>
Subject: Re: [PATCH 1/1] i2c: iproc: Add multi byte read-write support for
slave mode
Hi Rayagonda,
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@...adcom.com>
> Signed-off-by: Srinath Mannam <srinath.mannam@...adcom.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 */
>
This was already reviewed internally. I just reviewed it again and it
looks fine to me. Thanks.
Reviewed-by: Ray Jui <ray.jui@...adcom.com>
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