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Subject[PATCH v5 1/8] i2c: iproc: Extend I2C read up to 255 bytes
Date
From: Shreesha Rajashekar <shreesha@broadcom.com>

Add support to allow I2C master read transfer up to 255 bytes.

Signed-off-by: Shreesha Rajashekar <shreesha@broadcom.com>
Signed-off-by: Rayagonda Kokatanur <rayagonda.kokatanur@broadcom.com>
Signed-off-by: Ray Jui <ray.jui@broadcom.com>
---
drivers/i2c/busses/i2c-bcm-iproc.c | 98 +++++++++++++++++++++++-------
1 file changed, 76 insertions(+), 22 deletions(-)

diff --git a/drivers/i2c/busses/i2c-bcm-iproc.c b/drivers/i2c/busses/i2c-bcm-iproc.c
index 4c8c3bc4669c..eb7339a0280e 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 (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 +182,32 @@ 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;
+ }
+ /*
+ * bytes_left >= iproc_i2c->thld_bytes,
+ * hence no need to change the THRESHOLD SET.
+ * It will remain as iproc_i2c->thld_bytes itself
+ */
+ }
+
if (status & BIT(IS_M_START_BUSY_SHIFT)) {
iproc_i2c->xfer_is_done = 1;
complete(&iproc_i2c->done);
@@ -253,7 +305,7 @@ 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 +350,7 @@ 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 +359,7 @@ 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 +367,27 @@ 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 +419,6 @@ 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 +450,8 @@ static const struct i2c_algorithm bcm_iproc_algo = {
.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)
--
2.17.1
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