Master halt is issued after each byte of a transaction is processed in
IP version 3.3.
Master halt will stall the bus by holding the SCK line low until the
halt bit in the scb_general_control is cleared.
After the last byte of a transfer is processed we can use the Master
Halt interrupt to facilitate a repeated start transfer without
issuing a stop bit.
Signed-off-by: Sifan Naeem <sifan.naeem@xxxxxxxxxx>
---
drivers/i2c/busses/i2c-img-scb.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/drivers/i2c/busses/i2c-img-scb.c b/drivers/i2c/busses/i2c-img-scb.c
index 90faf48..df3d25a 100644
--- a/drivers/i2c/busses/i2c-img-scb.c
+++ b/drivers/i2c/busses/i2c-img-scb.c
@@ -151,6 +151,7 @@
#define INT_FIFO_EMPTYING BIT(12)
#define INT_TRANSACTION_DONE BIT(15)
#define INT_SLAVE_EVENT BIT(16)
+#define INT_MASTER_HALTED BIT(17)
#define INT_TIMING BIT(18)
#define INT_STOP_DETECTED BIT(19)
@@ -177,6 +178,7 @@
INT_FIFO_FULL | \
INT_FIFO_FILLING | \
INT_FIFO_EMPTY | \
+ INT_MASTER_HALTED | \
INT_STOP_DETECTED)
#define INT_ENABLE_MASK_WAITSTOP (INT_SLAVE_EVENT | \
@@ -901,6 +903,17 @@ static unsigned int img_i2c_auto(struct img_i2c *i2c,
mod_timer(&i2c->check_timer, jiffies + msecs_to_jiffies(1));
if (i2c->msg.flags & I2C_M_RD) {
+ if (int_status & INT_MASTER_HALTED) {
+ img_i2c_read_fifo(i2c);
+ if (i2c->msg.len == 0)
+ return ISR_COMPLETE(0);
+ /*
+ * Release and then enable transaction halt, to
+ * allow only a single byte to proceed.
+ */
+ img_i2c_transaction_halt(i2c, false);
+ img_i2c_transaction_halt(i2c, !i2c->last_msg);
+ }
if (int_status & INT_FIFO_FULL_FILLING) {
img_i2c_read_fifo(i2c);
if (i2c->msg.len == 0) {
@@ -922,6 +935,18 @@ static unsigned int img_i2c_auto(struct img_i2c *i2c,
return ISR_COMPLETE(ret);
}
} else {
+ if (int_status & INT_MASTER_HALTED) {
+ if ((int_status & INT_FIFO_EMPTY) &&
+ i2c->msg.len == 0)
+ return ISR_COMPLETE(0);
+ img_i2c_write_fifo(i2c);
+ /*
+ * Release and then enable transaction halt, to
+ * allow only a single byte to proceed.
+ */
+ img_i2c_transaction_halt(i2c, false);
+ img_i2c_transaction_halt(i2c, !i2c->last_msg);
+ }
if (int_status & INT_FIFO_EMPTY) {
if (i2c->msg.len == 0) {
if (i2c->last_msg)
--
1.7.9.5
--
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