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SubjectRe: [PATCH v2 1/8] i2c: iproc: I2C read up to 255 bytes support
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Hi Rayagonda,

On 1/16/2019 1:44 AM, Rayagonda Kokatanur wrote:
> From: Shreesha Rajashekar <shreesha@broadcom.com>
>
> Add support to allow I2C RX transfer up to 255 bytes.
>
> Signed-off-by: Rayagonda Kokatanur <rayagonda.kokatanur@broadcom.com>
> Signed-off-by: Shreesha Rajashekar <shreesha@broadcom.com>
> ---
> drivers/i2c/busses/i2c-bcm-iproc.c | 99 +++++++++++++++++++++++++++++---------
> 1 file changed, 77 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-bcm-iproc.c b/drivers/i2c/busses/i2c-bcm-iproc.c
> index 4c8c3bc4669c..f32a5e038314 100644
> --- a/drivers/i2c/busses/i2c-bcm-iproc.c
> +++ b/drivers/i2c/busses/i2c-bcm-iproc.c
> @@ -80,6 +80,10 @@
>
> #define I2C_TIMEOUT_MSEC 50000
> #define M_TX_RX_FIFO_SIZE 64
> +#define M_RX_FIFO_MAX_THLD_VALUE 63

probably make more sense to use:

#define M_RX_FIFO_MAX_THLD_VALUE (M_TX_RX_FIFO_SIZE - 1)
> +
> +#define M_RX_MAX_READ_LEN 255
> +#define M_RX_FIFO_THLD_VALUE 50
>
> enum bus_speed_index {
> I2C_SPD_100K = 0,
> @@ -102,17 +106,41 @@ struct bcm_iproc_i2c_dev {
>
> /* bytes that have been transferred */
> unsigned int tx_bytes;
> + /* bytes that have been read */
> + unsigned int rx_bytes;
> + unsigned int thld_bytes;
> };
>
> /*
> * Can be expanded in the future if more interrupt status bits are utilized
> */
> -#define ISR_MASK (BIT(IS_M_START_BUSY_SHIFT) | BIT(IS_M_TX_UNDERRUN_SHIFT))
> +#define ISR_MASK (BIT(IS_M_START_BUSY_SHIFT) | BIT(IS_M_TX_UNDERRUN_SHIFT)\
> + | BIT(IS_M_RX_THLD_SHIFT))
> +
> +static void bcm_iproc_i2c_read_valid_bytes(struct bcm_iproc_i2c_dev *iproc_i2c)
> +{
> + struct i2c_msg *msg = iproc_i2c->msg;
> +
> + /* Read valid data from RX FIFO */
> + while (iproc_i2c->rx_bytes < msg->len) {
> + if (!((readl(iproc_i2c->base +
> + M_FIFO_CTRL_OFFSET) >>
> + M_FIFO_RX_CNT_SHIFT) &
> + M_FIFO_RX_CNT_MASK))
> + break;
> +
> + msg->buf[iproc_i2c->rx_bytes] =
> + (readl(iproc_i2c->base + M_RX_OFFSET) >>
> + M_RX_DATA_SHIFT) & M_RX_DATA_MASK;
> + iproc_i2c->rx_bytes++;
> + }
> +}
>
> static irqreturn_t bcm_iproc_i2c_isr(int irq, void *data)
> {
> struct bcm_iproc_i2c_dev *iproc_i2c = data;
> u32 status = readl(iproc_i2c->base + IS_OFFSET);
> + u32 tmp;
>
> status &= ISR_MASK;
>
> @@ -136,8 +164,6 @@ static irqreturn_t bcm_iproc_i2c_isr(int irq, void *data)
>
> /* mark the last byte */
> if (idx == msg->len - 1) {
> - u32 tmp;
> -
> val |= BIT(M_TX_WR_STATUS_SHIFT);
>
> /*
> @@ -156,6 +182,33 @@ static irqreturn_t bcm_iproc_i2c_isr(int irq, void *data)
> iproc_i2c->tx_bytes += tx_bytes;
> }
>
> + if (status & BIT(IS_M_RX_THLD_SHIFT)) {
> + struct i2c_msg *msg = iproc_i2c->msg;
> + u32 bytes_left;
> +
> + bcm_iproc_i2c_read_valid_bytes(iproc_i2c);
> + bytes_left = msg->len - iproc_i2c->rx_bytes;
> + if (bytes_left == 0) {
> + /* finished reading all data, disable rx thld event */
> + tmp = readl(iproc_i2c->base + IE_OFFSET);
> + tmp &= ~BIT(IS_M_RX_THLD_SHIFT);
> + writel(tmp, iproc_i2c->base + IE_OFFSET);
> + } else if (bytes_left < iproc_i2c->thld_bytes) {
> + /* set bytes left as threshold */
> + tmp = readl(iproc_i2c->base + M_FIFO_CTRL_OFFSET);
> + tmp &= ~(M_FIFO_RX_THLD_MASK << M_FIFO_RX_THLD_SHIFT);
> + tmp |= (bytes_left << M_FIFO_RX_THLD_SHIFT);
> + writel(tmp, iproc_i2c->base + M_FIFO_CTRL_OFFSET);
> + iproc_i2c->thld_bytes = bytes_left;
> + } else {
> + /*
> + * bytes_left >= iproc_i2c->thld_bytes,
> + * hence no need to change the THRESHOLD SET.
> + * It will remain as iproc_i2c->thld_bytes itself
> + */

You can remove the else {} here but just leave the comment

> + }
> + }
> +
> if (status & BIT(IS_M_START_BUSY_SHIFT)) {
> iproc_i2c->xfer_is_done = 1;
> complete(&iproc_i2c->done);
> @@ -253,7 +306,7 @@ static int bcm_iproc_i2c_xfer_single_msg(struct bcm_iproc_i2c_dev *iproc_i2c,
> {
> int ret, i;
> u8 addr;
> - u32 val;
> + u32 val, tmp, val_intr_en;
> unsigned int tx_bytes;
> unsigned long time_left = msecs_to_jiffies(I2C_TIMEOUT_MSEC);
>
> @@ -298,7 +351,7 @@ static int bcm_iproc_i2c_xfer_single_msg(struct bcm_iproc_i2c_dev *iproc_i2c,
> * transaction is done, i.e., the internal start_busy bit, transitions
> * from 1 to 0.
> */
> - val = BIT(IE_M_START_BUSY_SHIFT);
> + val_intr_en = BIT(IE_M_START_BUSY_SHIFT);
>
> /*
> * If TX data size is larger than the TX FIFO, need to enable TX
> @@ -307,9 +360,7 @@ static int bcm_iproc_i2c_xfer_single_msg(struct bcm_iproc_i2c_dev *iproc_i2c,
> */
> if (!(msg->flags & I2C_M_RD) &&
> msg->len > iproc_i2c->tx_bytes)
> - val |= BIT(IE_M_TX_UNDERRUN_SHIFT);
> -
> - writel(val, iproc_i2c->base + IE_OFFSET);
> + val_intr_en |= BIT(IE_M_TX_UNDERRUN_SHIFT);
>
> /*
> * Now we can activate the transfer. For a read operation, specify the
> @@ -317,11 +368,27 @@ 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) {
> + iproc_i2c->rx_bytes = 0;
> + if (msg->len > M_RX_FIFO_MAX_THLD_VALUE)
> + iproc_i2c->thld_bytes = M_RX_FIFO_THLD_VALUE;
> + else
> + iproc_i2c->thld_bytes = msg->len;
> +
> + /* set threshold value */
> + tmp = readl(iproc_i2c->base + M_FIFO_CTRL_OFFSET);
> + tmp &= ~(M_FIFO_RX_THLD_MASK << M_FIFO_RX_THLD_SHIFT);
> + tmp |= iproc_i2c->thld_bytes << M_FIFO_RX_THLD_SHIFT;
> + writel(tmp, iproc_i2c->base + M_FIFO_CTRL_OFFSET);
> +
> + /* enable the RX threshold interrupt */
> + val_intr_en |= BIT(IE_M_RX_THLD_SHIFT);
> +
> val |= (M_CMD_PROTOCOL_BLK_RD << M_CMD_PROTOCOL_SHIFT) |
> (msg->len << M_CMD_RD_CNT_SHIFT);
> } else {
> val |= (M_CMD_PROTOCOL_BLK_WR << M_CMD_PROTOCOL_SHIFT);
> }
> + writel(val_intr_en, iproc_i2c->base + IE_OFFSET);
> writel(val, iproc_i2c->base + M_CMD_OFFSET);
>
> time_left = wait_for_completion_timeout(&iproc_i2c->done, time_left);
> @@ -353,17 +420,6 @@ static int bcm_iproc_i2c_xfer_single_msg(struct bcm_iproc_i2c_dev *iproc_i2c,
> return ret;
> }
>
> - /*
> - * For a read operation, we now need to load the data from FIFO
> - * into the memory buffer
> - */
> - if (msg->flags & I2C_M_RD) {
> - for (i = 0; i < msg->len; i++) {
> - msg->buf[i] = (readl(iproc_i2c->base + M_RX_OFFSET) >>
> - M_RX_DATA_SHIFT) & M_RX_DATA_MASK;
> - }
> - }
> -
> return 0;
> }
>
> @@ -395,9 +451,8 @@ static uint32_t bcm_iproc_i2c_functionality(struct i2c_adapter *adap)
> .functionality = bcm_iproc_i2c_functionality,
> };
>
> -static const struct i2c_adapter_quirks bcm_iproc_i2c_quirks = {
> - /* need to reserve one byte in the FIFO for the slave address */
> - .max_read_len = M_TX_RX_FIFO_SIZE - 1,
> +static struct i2c_adapter_quirks bcm_iproc_i2c_quirks = {
> + .max_read_len = M_RX_MAX_READ_LEN,
> };
>
> static int bcm_iproc_i2c_cfg_speed(struct bcm_iproc_i2c_dev *iproc_i2c)
>

Thanks,

Ray

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