i2c: Add configurable I2C transfer timeout

This patch introduces CONFIG_I2C_TRANSFER_TIMEOUT_US,
which controls how long to wait for an I2C devices to
produce/accept all the data bytes in a single transfer.
(The device can delay transfer by stretching the clock of
the ack bit.)

The default value of this new setting is 500ms.  Existing
code had timeouts anywhere from tens of milliseconds to a
full second beween various drivers.  Drivers can still have
their own shorter timeouts for setup/communication with the
I2C host controller (as opposed to transactions with I2C
devices on the bus.)

In general, the timeout is not meant to be reached except in
situations where there is already serious problem with the
boot, and serves to make sure that some useful diagnostic
output is produced on the console.

Change-Id: I6423122f32aad1dbcee0bfe240cdaa8cb512791f
Signed-off-by: Jes B. Klinke <jbk@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/62278
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>

1 files changed, 18 insertions, 14 deletions

diff --git a/src/soc/qualcomm/ipq40xx/qup.c b/src/soc/qualcomm/ipq40xx/qup.c
index 76f079744c..88e9169ec7 100644
--- a/src/soc/qualcomm/ipq40xx/qup.c
+++ b/src/soc/qualcomm/ipq40xx/qup.c
@@ -3,6 +3,7 @@
 #include <device/mmio.h>
 #include <console/console.h>
 #include <delay.h>
+#include <timer.h>
 #include <soc/iomap.h>
 #include <soc/qup.h>
 
@@ -93,35 +94,33 @@ static qup_return_t qup_reset_master_status(blsp_qup_id_t id)
 	return QUP_SUCCESS;
 }
 
-static qup_return_t qup_fifo_wait_for(blsp_qup_id_t id, uint32_t status)
+static qup_return_t qup_fifo_wait_for(blsp_qup_id_t id, uint32_t status,
+				      struct stopwatch *timeout)
 {
 	qup_return_t ret = QUP_ERR_UNDEFINED;
-	unsigned int count = TIMEOUT_CNT;
 
 	while (!(read32(QUP_ADDR(id, QUP_OPERATIONAL)) & status)) {
 		ret = qup_i2c_master_status(id);
 		if (ret)
 			return ret;
-		if (count == 0)
+		if (stopwatch_expired(timeout))
 			return QUP_ERR_TIMEOUT;
-		count--;
 	}
 
 	return QUP_SUCCESS;
 }
 
-static qup_return_t qup_fifo_wait_while(blsp_qup_id_t id, uint32_t status)
+static qup_return_t qup_fifo_wait_while(blsp_qup_id_t id, uint32_t status,
+					struct stopwatch *timeout)
 {
 	qup_return_t ret = QUP_ERR_UNDEFINED;
-	unsigned int count = TIMEOUT_CNT;
 
 	while (read32(QUP_ADDR(id, QUP_OPERATIONAL)) & status) {
 		ret = qup_i2c_master_status(id);
 		if (ret)
 			return ret;
-		if (count == 0)
+		if (stopwatch_expired(timeout))
 			return QUP_ERR_TIMEOUT;
-		count--;
 	}
 
 	return QUP_SUCCESS;
@@ -139,7 +138,8 @@ static inline uint32_t qup_i2c_create_output_tag(int stop, u8 data)
 	return tag;
 }
 
-static inline qup_return_t qup_i2c_write_fifo_flush(blsp_qup_id_t id)
+static inline qup_return_t qup_i2c_write_fifo_flush(blsp_qup_id_t id,
+						    struct stopwatch *timeout)
 {
 	qup_return_t ret = QUP_ERR_UNDEFINED;
 
@@ -147,7 +147,7 @@ static inline qup_return_t qup_i2c_write_fifo_flush(blsp_qup_id_t id)
 
 	mdelay(4);	/* TPM seems to need this */
 
-	ret = qup_fifo_wait_while(id, OUTPUT_FIFO_NOT_EMPTY);
+	ret = qup_fifo_wait_while(id, OUTPUT_FIFO_NOT_EMPTY, timeout);
 	if (ret)
 		return ret;
 
@@ -168,6 +168,7 @@ static qup_return_t qup_i2c_write_fifo(blsp_qup_id_t id, qup_data_t *p_tx_obj,
 	unsigned int data_len = p_tx_obj->p.iic.data_len;
 	unsigned int idx = 0;
 	uint32_t tag, *fifo = QUP_ADDR(id, QUP_OUTPUT_FIFO);
+	struct stopwatch timeout;
 
 	qup_reset_master_status(id);
 
@@ -196,6 +197,7 @@ static qup_return_t qup_i2c_write_fifo(blsp_qup_id_t id, qup_data_t *p_tx_obj,
 
 	qup_write32(fifo, tag);
 
+	stopwatch_init_usecs_expire(&timeout, CONFIG_I2C_TRANSFER_TIMEOUT_US);
 	while (data_len) {
 
 		tag = qup_i2c_create_output_tag(data_len == 1 && stop_seq,
@@ -213,7 +215,7 @@ static qup_return_t qup_i2c_write_fifo(blsp_qup_id_t id, qup_data_t *p_tx_obj,
 
 		qup_write32(fifo, tag);
 
-		ret = qup_i2c_write_fifo_flush(id);
+		ret = qup_i2c_write_fifo_flush(id, &timeout);
 
 		if (ret) {
 			printk(QUPDBG "%s: error\n", __func__);
@@ -221,7 +223,7 @@ static qup_return_t qup_i2c_write_fifo(blsp_qup_id_t id, qup_data_t *p_tx_obj,
 		}
 	}
 
-	ret = qup_i2c_write_fifo_flush(id);
+	ret = qup_i2c_write_fifo_flush(id, &timeout);
 
 	qup_set_state(id, QUP_STATE_RESET);
 
@@ -285,6 +287,7 @@ static qup_return_t qup_i2c_read_fifo(blsp_qup_id_t id, qup_data_t *p_tx_obj)
 	unsigned int data_len = p_tx_obj->p.iic.data_len;
 	unsigned int idx = 0;
 	uint32_t *fifo = QUP_ADDR(id, QUP_OUTPUT_FIFO);
+	struct stopwatch timeout;
 
 	qup_reset_master_status(id);
 
@@ -303,13 +306,14 @@ static qup_return_t qup_i2c_read_fifo(blsp_qup_id_t id, qup_data_t *p_tx_obj)
 				  (QUP_I2C_ADDR(addr) | QUP_I2C_SLAVE_READ)) |
 				((QUP_I2C_RECV_SEQ | data_len) << 16));
 
-	ret = qup_i2c_write_fifo_flush(id);
+	stopwatch_init_usecs_expire(&timeout, CONFIG_I2C_TRANSFER_TIMEOUT_US);
+	ret = qup_i2c_write_fifo_flush(id, &timeout);
 	if (ret) {
 		printk(QUPDBG "%s: OUTPUT_FIFO_NOT_EMPTY\n", __func__);
 		return ret;
 	}
 
-	ret = qup_fifo_wait_for(id, INPUT_SERVICE_FLAG);
+	ret = qup_fifo_wait_for(id, INPUT_SERVICE_FLAG, &timeout);
 	if (ret) {
 		printk(QUPDBG "%s: INPUT_SERVICE_FLAG\n", __func__);
 		return ret;