[PATCH 1/1] i2c: iproc: Add multi byte read-write support for slave mode
From: Rayagonda Kokatanur
Date: Thu May 09 2019 - 00:09:06 EST
Add multiple byte read-write support for slave mode.
Signed-off-by: Rayagonda Kokatanur <rayagonda.kokatanur@xxxxxxxxxxxx>
Signed-off-by: Srinath Mannam <srinath.mannam@xxxxxxxxxxxx>
---
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 */
--
1.9.1