diff mbox series

i2c-qcom-cci: Support repeated start mode.

Message ID 1557014133-24388-1-git-send-email-klawson@lisden.com
State New
Headers show
Series i2c-qcom-cci: Support repeated start mode. | expand

Commit Message

Kelvin Lawson May 4, 2019, 11:55 p.m. UTC 
Support repeated start mode. Don't send a STOP if it's part
of a group of transactions (e.g. write of register address followed by a
register value read).

Signed-off-by: Kelvin Lawson <klawson@lisden.com>

---
 drivers/i2c/busses/i2c-qcom-cci.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

-- 
2.7.4
diff mbox series

Patch

diff --git a/drivers/i2c/busses/i2c-qcom-cci.c b/drivers/i2c/busses/i2c-qcom-cci.c
index 143e44d..1032e16 100644
--- a/drivers/i2c/busses/i2c-qcom-cci.c
+++ b/drivers/i2c/busses/i2c-qcom-cci.c
@@ -512,7 +512,8 @@  static int cci_i2c_read(struct cci *cci, u16 addr, u8 *buf, u16 len)
 	return 0;
 }
 
-static int cci_i2c_write(struct cci *cci, u16 addr, u8 *buf, u16 len)
+static int cci_i2c_write(struct cci *cci, u16 addr, u8 *buf, u16 len,
+			 int disable_stop)
 {
 	u8 master = 0;
 	u8 queue = QUEUE_0;
@@ -533,7 +534,8 @@  static int cci_i2c_write(struct cci *cci, u16 addr, u8 *buf, u16 len)
 	writel(val, cci->base + CCI_I2C_Mm_Qn_LOAD_DATA(master, queue));
 
 	i = 0;
-	load[i++] = CCI_I2C_WRITE | len << 4;
+	load[i++] = (disable_stop ? CCI_I2C_WRITE_DISABLE_P : CCI_I2C_WRITE)
+		    | len << 4;
 
 	for (j = 0; j < len; j++)
 		load[i++] = buf[j];
@@ -557,6 +559,13 @@  static int cci_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
 	struct cci *cci = i2c_get_adapdata(adap);
 	int i;
 	int ret = 0;
+	int disable_stop = 0;
+
+	/*
+	 * Use repeated start (no STOP bit on writes) if this is a group of
+	 * transactions (e.g. write register address followed by read data).
+	 */
+	disable_stop = num > 1;
 
 	for (i = 0; i < num; i++) {
 		if (msgs[i].flags & I2C_M_RD)