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SubjectRe: [PATCH v2 12/13] i2c: qup: reorganization of driver code to remove polling for qup v1
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Hi Abhishek,

On 3/12/2018 6:45 PM, Abhishek Sahu wrote:
> Following are the major issues in current driver code
>
> 1. The current driver simply assumes the transfer completion
> whenever its gets any non-error interrupts and then simply do the
> polling of available/free bytes in FIFO.
> 2. The block mode is not working properly since no handling in
> being done for OUT_BLOCK_WRITE_REQ and IN_BLOCK_READ_REQ.
>
> Because of above, i2c v1 transfers of size greater than 32 are failing
> with following error message
>
> i2c_qup 78b6000.i2c: timeout for fifo out full
>
> To make block mode working properly and move to use the interrupts
> instead of polling, major code reorganization is required. Following
> are the major changes done in this patch
>
> 1. Remove the polling of TX FIFO free space and RX FIFO available
> bytes and move to interrupts completely. QUP has QUP_MX_OUTPUT_DONE,
> QUP_MX_INPUT_DONE, OUT_BLOCK_WRITE_REQ and IN_BLOCK_READ_REQ
> interrupts to handle FIFO’s properly so check all these interrupts.
> 2. During write, For FIFO mode, TX FIFO can be directly written
> without checking for FIFO space. For block mode, the QUP will generate
> OUT_BLOCK_WRITE_REQ interrupt whenever it has block size of available
> space.
> 3. During read, both TX and RX FIFO will be used. TX will be used
> for writing tags and RX will be used for receiving the data. In QUP,
> TX and RX can operate in separate mode so configure modes accordingly.
> 4. For read FIFO mode, wait for QUP_MX_INPUT_DONE interrupt which
> will be generated after all the bytes have been copied in RX FIFO. For
> read Block mode, QUP will generate IN_BLOCK_READ_REQ interrupts
> whenever it has block size of available data.
>
> Signed-off-by: Abhishek Sahu <absahu@codeaurora.org>
> ---
>

Reviewed-by: Sricharan R <sricharan@codeaurora.org>

Regards,
Sricharan



> * Changes from v1:
>
> 1. Fixed auto build test WARNING ‘idx' may be used uninitialized
> in this function
> 2. Removed event-based completion and changed transfer completion
> detection logic in interrupt handler
>
> drivers/i2c/busses/i2c-qup.c | 368 ++++++++++++++++++++++++++-----------------
> 1 file changed, 224 insertions(+), 144 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-qup.c b/drivers/i2c/busses/i2c-qup.c
> index 4ebd922..3bf3c34 100644
> --- a/drivers/i2c/busses/i2c-qup.c
> +++ b/drivers/i2c/busses/i2c-qup.c
> @@ -64,8 +64,11 @@
> #define QUP_IN_SVC_FLAG BIT(9)
> #define QUP_MX_OUTPUT_DONE BIT(10)
> #define QUP_MX_INPUT_DONE BIT(11)
> +#define OUT_BLOCK_WRITE_REQ BIT(12)
> +#define IN_BLOCK_READ_REQ BIT(13)
>
> /* I2C mini core related values */
> +#define QUP_NO_INPUT BIT(7)
> #define QUP_CLOCK_AUTO_GATE BIT(13)
> #define I2C_MINI_CORE (2 << 8)
> #define I2C_N_VAL 15
> @@ -137,13 +140,36 @@
> #define DEFAULT_CLK_FREQ 100000
> #define DEFAULT_SRC_CLK 20000000
>
> +/*
> + * count: no of blocks
> + * pos: current block number
> + * tx_tag_len: tx tag length for current block
> + * rx_tag_len: rx tag length for current block
> + * data_len: remaining data length for current message
> + * total_tx_len: total tx length including tag bytes for current QUP transfer
> + * total_rx_len: total rx length including tag bytes for current QUP transfer
> + * tx_fifo_free: number of free bytes in current QUP block write.
> + * fifo_available: number of available bytes in RX FIFO for current
> + * QUP block read
> + * rx_bytes_read: if all the bytes have been read from rx FIFO.
> + * is_tx_blk_mode: whether tx uses block or FIFO mode in case of non BAM xfer.
> + * is_rx_blk_mode: whether rx uses block or FIFO mode in case of non BAM xfer.
> + * tags: contains tx tag bytes for current QUP transfer
> + */
> struct qup_i2c_block {
> - int count;
> - int pos;
> - int tx_tag_len;
> - int rx_tag_len;
> - int data_len;
> - u8 tags[6];
> + int count;
> + int pos;
> + int tx_tag_len;
> + int rx_tag_len;
> + int data_len;
> + int total_tx_len;
> + int total_rx_len;
> + int tx_fifo_free;
> + int fifo_available;
> + bool rx_bytes_read;
> + bool is_tx_blk_mode;
> + bool is_rx_blk_mode;
> + u8 tags[6];
> };
>
> struct qup_i2c_tag {
> @@ -186,6 +212,7 @@ struct qup_i2c_dev {
>
> /* To check if this is the last msg */
> bool is_last;
> + bool is_qup_v1;
>
> /* To configure when bus is in run state */
> int config_run;
> @@ -202,11 +229,18 @@ struct qup_i2c_dev {
> struct qup_i2c_bam btx;
>
> struct completion xfer;
> + /* function to write data in tx fifo */
> + void (*write_tx_fifo)(struct qup_i2c_dev *qup);
> + /* function to read data from rx fifo */
> + void (*read_rx_fifo)(struct qup_i2c_dev *qup);
> + /* function to write tags in tx fifo for i2c read transfer */
> + void (*write_rx_tags)(struct qup_i2c_dev *qup);
> };
>
> static irqreturn_t qup_i2c_interrupt(int irq, void *dev)
> {
> struct qup_i2c_dev *qup = dev;
> + struct qup_i2c_block *blk = &qup->blk;
> u32 bus_err;
> u32 qup_err;
> u32 opflags;
> @@ -253,12 +287,48 @@ static irqreturn_t qup_i2c_interrupt(int irq, void *dev)
> goto done;
> }
>
> - if (opflags & QUP_IN_SVC_FLAG)
> - writel(QUP_IN_SVC_FLAG, qup->base + QUP_OPERATIONAL);
> + if (!qup->is_qup_v1)
> + goto done;
>
> - if (opflags & QUP_OUT_SVC_FLAG)
> + if (opflags & QUP_OUT_SVC_FLAG) {
> writel(QUP_OUT_SVC_FLAG, qup->base + QUP_OPERATIONAL);
>
> + if (opflags & OUT_BLOCK_WRITE_REQ) {
> + blk->tx_fifo_free += qup->out_blk_sz;
> + if (qup->msg->flags & I2C_M_RD)
> + qup->write_rx_tags(qup);
> + else
> + qup->write_tx_fifo(qup);
> + }
> + }
> +
> + if (opflags & QUP_IN_SVC_FLAG) {
> + writel(QUP_IN_SVC_FLAG, qup->base + QUP_OPERATIONAL);
> +
> + if (!blk->is_rx_blk_mode) {
> + blk->fifo_available += qup->in_fifo_sz;
> + qup->read_rx_fifo(qup);
> + } else if (opflags & IN_BLOCK_READ_REQ) {
> + blk->fifo_available += qup->in_blk_sz;
> + qup->read_rx_fifo(qup);
> + }
> + }
> +
> + if (qup->msg->flags & I2C_M_RD) {
> + if (!blk->rx_bytes_read)
> + return IRQ_HANDLED;
> + } else {
> + /*
> + * Ideally, QUP_MAX_OUTPUT_DONE_FLAG should be checked
> + * for FIFO mode also. But, QUP_MAX_OUTPUT_DONE_FLAG lags
> + * behind QUP_OUTPUT_SERVICE_FLAG sometimes. The only reason
> + * of interrupt for write message in FIFO mode is
> + * QUP_MAX_OUTPUT_DONE_FLAG condition.
> + */
> + if (blk->is_tx_blk_mode && !(opflags & QUP_MX_OUTPUT_DONE))
> + return IRQ_HANDLED;
> + }
> +
> done:
> qup->qup_err = qup_err;
> qup->bus_err = bus_err;
> @@ -324,6 +394,28 @@ static int qup_i2c_change_state(struct qup_i2c_dev *qup, u32 state)
> return 0;
> }
>
> +/* Check if I2C bus returns to IDLE state */
> +static int qup_i2c_bus_active(struct qup_i2c_dev *qup, int len)
> +{
> + unsigned long timeout;
> + u32 status;
> + int ret = 0;
> +
> + timeout = jiffies + len * 4;
> + for (;;) {
> + status = readl(qup->base + QUP_I2C_STATUS);
> + if (!(status & I2C_STATUS_BUS_ACTIVE))
> + break;
> +
> + if (time_after(jiffies, timeout))
> + ret = -ETIMEDOUT;
> +
> + usleep_range(len, len * 2);
> + }
> +
> + return ret;
> +}
> +
> /**
> * qup_i2c_wait_ready - wait for a give number of bytes in tx/rx path
> * @qup: The qup_i2c_dev device
> @@ -394,23 +486,6 @@ static void qup_i2c_set_write_mode_v2(struct qup_i2c_dev *qup,
> }
> }
>
> -static void qup_i2c_set_write_mode(struct qup_i2c_dev *qup, struct i2c_msg *msg)
> -{
> - /* Number of entries to shift out, including the start */
> - int total = msg->len + 1;
> -
> - if (total < qup->out_fifo_sz) {
> - /* FIFO mode */
> - writel(QUP_REPACK_EN, qup->base + QUP_IO_MODE);
> - writel(total, qup->base + QUP_MX_WRITE_CNT);
> - } else {
> - /* BLOCK mode (transfer data on chunks) */
> - writel(QUP_OUTPUT_BLK_MODE | QUP_REPACK_EN,
> - qup->base + QUP_IO_MODE);
> - writel(total, qup->base + QUP_MX_OUTPUT_CNT);
> - }
> -}
> -
> static int check_for_fifo_space(struct qup_i2c_dev *qup)
> {
> int ret;
> @@ -443,28 +518,25 @@ static int check_for_fifo_space(struct qup_i2c_dev *qup)
> return ret;
> }
>
> -static int qup_i2c_issue_write(struct qup_i2c_dev *qup, struct i2c_msg *msg)
> +static void qup_i2c_write_tx_fifo_v1(struct qup_i2c_dev *qup)
> {
> + struct qup_i2c_block *blk = &qup->blk;
> + struct i2c_msg *msg = qup->msg;
> u32 addr = msg->addr << 1;
> u32 qup_tag;
> int idx;
> u32 val;
> - int ret = 0;
>
> if (qup->pos == 0) {
> val = QUP_TAG_START | addr;
> idx = 1;
> + blk->tx_fifo_free--;
> } else {
> val = 0;
> idx = 0;
> }
>
> - while (qup->pos < msg->len) {
> - /* Check that there's space in the FIFO for our pair */
> - ret = check_for_fifo_space(qup);
> - if (ret)
> - return ret;
> -
> + while (blk->tx_fifo_free && qup->pos < msg->len) {
> if (qup->pos == msg->len - 1)
> qup_tag = QUP_TAG_STOP;
> else
> @@ -481,11 +553,8 @@ static int qup_i2c_issue_write(struct qup_i2c_dev *qup, struct i2c_msg *msg)
>
> qup->pos++;
> idx++;
> + blk->tx_fifo_free--;
> }
> -
> - ret = qup_i2c_change_state(qup, QUP_RUN_STATE);
> -
> - return ret;
> }
>
> static void qup_i2c_set_blk_data(struct qup_i2c_dev *qup,
> @@ -1006,64 +1075,6 @@ static int qup_i2c_write_one_v2(struct qup_i2c_dev *qup, struct i2c_msg *msg)
> return ret;
> }
>
> -static int qup_i2c_write_one(struct qup_i2c_dev *qup, struct i2c_msg *msg)
> -{
> - int ret;
> -
> - qup->msg = msg;
> - qup->pos = 0;
> -
> - enable_irq(qup->irq);
> -
> - qup_i2c_set_write_mode(qup, msg);
> -
> - ret = qup_i2c_change_state(qup, QUP_RUN_STATE);
> - if (ret)
> - goto err;
> -
> - writel(qup->clk_ctl, qup->base + QUP_I2C_CLK_CTL);
> -
> - do {
> - ret = qup_i2c_change_state(qup, QUP_PAUSE_STATE);
> - if (ret)
> - goto err;
> -
> - ret = qup_i2c_issue_write(qup, msg);
> - if (ret)
> - goto err;
> -
> - ret = qup_i2c_change_state(qup, QUP_RUN_STATE);
> - if (ret)
> - goto err;
> -
> - ret = qup_i2c_wait_for_complete(qup, msg);
> - if (ret)
> - goto err;
> - } while (qup->pos < msg->len);
> -
> - /* Wait for the outstanding data in the fifo to drain */
> - ret = qup_i2c_wait_ready(qup, QUP_OUT_NOT_EMPTY, RESET_BIT, ONE_BYTE);
> -err:
> - disable_irq(qup->irq);
> - qup->msg = NULL;
> -
> - return ret;
> -}
> -
> -static void qup_i2c_set_read_mode(struct qup_i2c_dev *qup, int len)
> -{
> - if (len < qup->in_fifo_sz) {
> - /* FIFO mode */
> - writel(QUP_REPACK_EN, qup->base + QUP_IO_MODE);
> - writel(len, qup->base + QUP_MX_READ_CNT);
> - } else {
> - /* BLOCK mode (transfer data on chunks) */
> - writel(QUP_INPUT_BLK_MODE | QUP_REPACK_EN,
> - qup->base + QUP_IO_MODE);
> - writel(len, qup->base + QUP_MX_INPUT_CNT);
> - }
> -}
> -
> static void qup_i2c_set_read_mode_v2(struct qup_i2c_dev *qup, int len)
> {
> int tx_len = qup->blk.tx_tag_len;
> @@ -1086,44 +1097,27 @@ static void qup_i2c_set_read_mode_v2(struct qup_i2c_dev *qup, int len)
> }
> }
>
> -static void qup_i2c_issue_read(struct qup_i2c_dev *qup, struct i2c_msg *msg)
> -{
> - u32 addr, len, val;
> -
> - addr = i2c_8bit_addr_from_msg(msg);
> -
> - /* 0 is used to specify a length 256 (QUP_READ_LIMIT) */
> - len = (msg->len == QUP_READ_LIMIT) ? 0 : msg->len;
> -
> - val = ((QUP_TAG_REC | len) << QUP_MSW_SHIFT) | QUP_TAG_START | addr;
> - writel(val, qup->base + QUP_OUT_FIFO_BASE);
> -}
> -
> -
> -static int qup_i2c_read_fifo(struct qup_i2c_dev *qup, struct i2c_msg *msg)
> +static void qup_i2c_read_rx_fifo_v1(struct qup_i2c_dev *qup)
> {
> + struct qup_i2c_block *blk = &qup->blk;
> + struct i2c_msg *msg = qup->msg;
> u32 val = 0;
> - int idx;
> - int ret = 0;
> + int idx = 0;
>
> - for (idx = 0; qup->pos < msg->len; idx++) {
> + while (blk->fifo_available && qup->pos < msg->len) {
> if ((idx & 1) == 0) {
> - /* Check that FIFO have data */
> - ret = qup_i2c_wait_ready(qup, QUP_IN_NOT_EMPTY,
> - SET_BIT, 4 * ONE_BYTE);
> - if (ret)
> - return ret;
> -
> /* Reading 2 words at time */
> val = readl(qup->base + QUP_IN_FIFO_BASE);
> -
> msg->buf[qup->pos++] = val & 0xFF;
> } else {
> msg->buf[qup->pos++] = val >> QUP_MSW_SHIFT;
> }
> + idx++;
> + blk->fifo_available--;
> }
>
> - return ret;
> + if (qup->pos == msg->len)
> + blk->rx_bytes_read = true;
> }
>
> static int qup_i2c_read_fifo_v2(struct qup_i2c_dev *qup,
> @@ -1224,49 +1218,130 @@ static int qup_i2c_read_one_v2(struct qup_i2c_dev *qup, struct i2c_msg *msg)
> return ret;
> }
>
> -static int qup_i2c_read_one(struct qup_i2c_dev *qup, struct i2c_msg *msg)
> +static void qup_i2c_write_rx_tags_v1(struct qup_i2c_dev *qup)
> {
> + struct i2c_msg *msg = qup->msg;
> + u32 addr, len, val;
> +
> + addr = i2c_8bit_addr_from_msg(msg);
> +
> + /* 0 is used to specify a length 256 (QUP_READ_LIMIT) */
> + len = (msg->len == QUP_READ_LIMIT) ? 0 : msg->len;
> +
> + val = ((QUP_TAG_REC | len) << QUP_MSW_SHIFT) | QUP_TAG_START | addr;
> + writel(val, qup->base + QUP_OUT_FIFO_BASE);
> +}
> +
> +static void qup_i2c_conf_v1(struct qup_i2c_dev *qup)
> +{
> + struct qup_i2c_block *blk = &qup->blk;
> + u32 qup_config = I2C_MINI_CORE | I2C_N_VAL;
> + u32 io_mode = QUP_REPACK_EN;
> +
> + blk->is_tx_blk_mode =
> + blk->total_tx_len > qup->out_fifo_sz ? true : false;
> + blk->is_rx_blk_mode =
> + blk->total_rx_len > qup->in_fifo_sz ? true : false;
> +
> + if (blk->is_tx_blk_mode) {
> + io_mode |= QUP_OUTPUT_BLK_MODE;
> + writel(0, qup->base + QUP_MX_WRITE_CNT);
> + writel(blk->total_tx_len, qup->base + QUP_MX_OUTPUT_CNT);
> + } else {
> + writel(0, qup->base + QUP_MX_OUTPUT_CNT);
> + writel(blk->total_tx_len, qup->base + QUP_MX_WRITE_CNT);
> + }
> +
> + if (blk->total_rx_len) {
> + if (blk->is_rx_blk_mode) {
> + io_mode |= QUP_INPUT_BLK_MODE;
> + writel(0, qup->base + QUP_MX_READ_CNT);
> + writel(blk->total_rx_len, qup->base + QUP_MX_INPUT_CNT);
> + } else {
> + writel(0, qup->base + QUP_MX_INPUT_CNT);
> + writel(blk->total_rx_len, qup->base + QUP_MX_READ_CNT);
> + }
> + } else {
> + qup_config |= QUP_NO_INPUT;
> + }
> +
> + writel(qup_config, qup->base + QUP_CONFIG);
> + writel(io_mode, qup->base + QUP_IO_MODE);
> +}
> +
> +static void qup_i2c_clear_blk_v1(struct qup_i2c_block *blk)
> +{
> + blk->tx_fifo_free = 0;
> + blk->fifo_available = 0;
> + blk->rx_bytes_read = false;
> +}
> +
> +static int qup_i2c_conf_xfer_v1(struct qup_i2c_dev *qup, bool is_rx)
> +{
> + struct qup_i2c_block *blk = &qup->blk;
> int ret;
>
> - qup->msg = msg;
> - qup->pos = 0;
> -
> - enable_irq(qup->irq);
> - qup_i2c_set_read_mode(qup, msg->len);
> -
> + qup_i2c_clear_blk_v1(blk);
> + qup_i2c_conf_v1(qup);
> ret = qup_i2c_change_state(qup, QUP_RUN_STATE);
> if (ret)
> - goto err;
> + return ret;
>
> writel(qup->clk_ctl, qup->base + QUP_I2C_CLK_CTL);
>
> ret = qup_i2c_change_state(qup, QUP_PAUSE_STATE);
> if (ret)
> - goto err;
> + return ret;
>
> - qup_i2c_issue_read(qup, msg);
> + reinit_completion(&qup->xfer);
> + enable_irq(qup->irq);
> + if (!blk->is_tx_blk_mode) {
> + blk->tx_fifo_free = qup->out_fifo_sz;
> +
> + if (is_rx)
> + qup_i2c_write_rx_tags_v1(qup);
> + else
> + qup_i2c_write_tx_fifo_v1(qup);
> + }
>
> ret = qup_i2c_change_state(qup, QUP_RUN_STATE);
> if (ret)
> goto err;
>
> - do {
> - ret = qup_i2c_wait_for_complete(qup, msg);
> - if (ret)
> - goto err;
> + ret = qup_i2c_wait_for_complete(qup, qup->msg);
> + if (ret)
> + goto err;
>
> - ret = qup_i2c_read_fifo(qup, msg);
> - if (ret)
> - goto err;
> - } while (qup->pos < msg->len);
> + ret = qup_i2c_bus_active(qup, ONE_BYTE);
>
> err:
> disable_irq(qup->irq);
> - qup->msg = NULL;
> -
> return ret;
> }
>
> +static int qup_i2c_write_one(struct qup_i2c_dev *qup)
> +{
> + struct i2c_msg *msg = qup->msg;
> + struct qup_i2c_block *blk = &qup->blk;
> +
> + qup->pos = 0;
> + blk->total_tx_len = msg->len + 1;
> + blk->total_rx_len = 0;
> +
> + return qup_i2c_conf_xfer_v1(qup, false);
> +}
> +
> +static int qup_i2c_read_one(struct qup_i2c_dev *qup)
> +{
> + struct qup_i2c_block *blk = &qup->blk;
> +
> + qup->pos = 0;
> + blk->total_tx_len = 2;
> + blk->total_rx_len = qup->msg->len;
> +
> + return qup_i2c_conf_xfer_v1(qup, true);
> +}
> +
> static int qup_i2c_xfer(struct i2c_adapter *adap,
> struct i2c_msg msgs[],
> int num)
> @@ -1305,10 +1380,11 @@ static int qup_i2c_xfer(struct i2c_adapter *adap,
> goto out;
> }
>
> + qup->msg = &msgs[idx];
> if (msgs[idx].flags & I2C_M_RD)
> - ret = qup_i2c_read_one(qup, &msgs[idx]);
> + ret = qup_i2c_read_one(qup);
> else
> - ret = qup_i2c_write_one(qup, &msgs[idx]);
> + ret = qup_i2c_write_one(qup);
>
> if (ret)
> break;
> @@ -1487,6 +1563,10 @@ static int qup_i2c_probe(struct platform_device *pdev)
> if (of_device_is_compatible(pdev->dev.of_node, "qcom,i2c-qup-v1.1.1")) {
> qup->adap.algo = &qup_i2c_algo;
> qup->adap.quirks = &qup_i2c_quirks;
> + qup->is_qup_v1 = true;
> + qup->write_tx_fifo = qup_i2c_write_tx_fifo_v1;
> + qup->read_rx_fifo = qup_i2c_read_rx_fifo_v1;
> + qup->write_rx_tags = qup_i2c_write_rx_tags_v1;
> } else {
> qup->adap.algo = &qup_i2c_algo_v2;
> ret = qup_i2c_req_dma(qup);
>

--
"QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation

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