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Subject[PATCH 11/12] i2c: qup: reorganization of driver code to remove polling for qup v1
Date
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>
---
drivers/i2c/busses/i2c-qup.c | 399 ++++++++++++++++++++++++++++---------------
1 file changed, 257 insertions(+), 142 deletions(-)

diff --git a/drivers/i2c/busses/i2c-qup.c b/drivers/i2c/busses/i2c-qup.c
index edea3b9..af6c21a 100644
--- a/drivers/i2c/busses/i2c-qup.c
+++ b/drivers/i2c/busses/i2c-qup.c
@@ -73,8 +73,11 @@
#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
@@ -138,13 +141,51 @@
#define DEFAULT_CLK_FREQ 100000
#define DEFAULT_SRC_CLK 20000000

+/* MAX_OUTPUT_DONE_FLAG has been received */
+#define QUP_BLK_EVENT_TX_IRQ_DONE BIT(0)
+/* MAX_INPUT_DONE_FLAG has been received */
+#define QUP_BLK_EVENT_RX_IRQ_DONE BIT(1)
+/* All the TX bytes have been written in TX FIFO */
+#define QUP_BLK_EVENT_TX_DATA_DONE BIT(2)
+/* All the RX bytes have been read from RX FIFO */
+#define QUP_BLK_EVENT_RX_DATA_DONE BIT(3)
+
+/* All the required events to mark a QUP I2C TX transfer completed */
+#define QUP_BLK_EVENT_TX_DONE (QUP_BLK_EVENT_TX_IRQ_DONE | \
+ QUP_BLK_EVENT_TX_DATA_DONE)
+/* All the required events to mark a QUP I2C RX transfer completed */
+#define QUP_BLK_EVENT_RX_DONE (QUP_BLK_EVENT_TX_DONE | \
+ QUP_BLK_EVENT_RX_IRQ_DONE | \
+ QUP_BLK_EVENT_RX_DATA_DONE)
+
+/*
+ * 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
+ * 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 is_tx_blk_mode;
+ bool is_rx_blk_mode;
+ u8 tags[6];
};

struct qup_i2c_tag {
@@ -187,6 +228,7 @@ 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;
@@ -195,6 +237,10 @@ struct qup_i2c_dev {
bool is_dma;
/* To check if the current transfer is using DMA */
bool use_dma;
+ /* Required events to mark QUP transfer as completed */
+ u32 blk_events;
+ /* Already completed events in QUP transfer */
+ u32 cur_blk_events;
/* The threshold length above which DMA will be used */
unsigned int dma_threshold;
unsigned int max_xfer_sg_len;
@@ -205,11 +251,18 @@ 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;
@@ -256,12 +309,54 @@ 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);

+ /*
+ * Ideally, would like to check QUP_MAX_OUTPUT_DONE_FLAG.
+ * However, QUP_MAX_OUTPUT_DONE_FLAG is lagging behind
+ * QUP_OUTPUT_SERVICE_FLAG. The only reason for
+ * QUP_OUTPUT_SERVICE_FLAG to be set in FIFO mode is
+ * QUP_MAX_OUTPUT_DONE_FLAG condition. The code checking
+ * here QUP_OUTPUT_SERVICE_FLAG and assumes that
+ * QUP_MAX_OUTPUT_DONE_FLAG.
+ */
+ if (!blk->is_tx_blk_mode)
+ qup->cur_blk_events |= QUP_BLK_EVENT_TX_IRQ_DONE;
+
+ 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 (opflags & QUP_MX_OUTPUT_DONE)
+ qup->cur_blk_events |= QUP_BLK_EVENT_TX_IRQ_DONE;
+
+ if (opflags & QUP_MX_INPUT_DONE)
+ qup->cur_blk_events |= QUP_BLK_EVENT_RX_IRQ_DONE;
+
+ if (qup->cur_blk_events != qup->blk_events)
+ return IRQ_HANDLED;
+
done:
qup->qup_err = qup_err;
qup->bus_err = bus_err;
@@ -327,6 +422,28 @@ 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
@@ -397,23 +514,6 @@ 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;
@@ -446,28 +546,25 @@ 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
@@ -484,11 +581,11 @@ 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;
+ if (qup->pos == msg->len)
+ qup->cur_blk_events |= QUP_BLK_EVENT_TX_DATA_DONE;
}

static void qup_i2c_set_blk_data(struct qup_i2c_dev *qup,
@@ -1009,64 +1106,6 @@ 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;
@@ -1089,44 +1128,27 @@ 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;

- 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)
+ qup->cur_blk_events |= QUP_BLK_EVENT_RX_DATA_DONE;
}

static int qup_i2c_read_fifo_v2(struct qup_i2c_dev *qup,
@@ -1227,49 +1249,137 @@ 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_set_blk_event(struct qup_i2c_dev *qup, bool is_rx)
{
+ qup->cur_blk_events = 0;
+ qup->blk_events = is_rx ? QUP_BLK_EVENT_RX_DONE : QUP_BLK_EVENT_TX_DONE;
+}
+
+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);
+ qup->cur_blk_events |= QUP_BLK_EVENT_TX_DATA_DONE;
+}
+
+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;
+}
+
+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);
+ qup_i2c_set_blk_event(qup, is_rx);
+ 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)
@@ -1308,10 +1418,11 @@ 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;
@@ -1489,6 +1600,10 @@ 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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