This is in preparation of supporting write-only SDA in i2c-gpio.
Signed-off-by: Heiner Kallweit <hkallweit1@xxxxxxxxx>
---
drivers/i2c/algos/i2c-algo-bit.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)
diff --git a/drivers/i2c/algos/i2c-algo-bit.c b/drivers/i2c/algos/i2c-algo-bit.c
index fc90293af..ab5a73e90 100644
--- a/drivers/i2c/algos/i2c-algo-bit.c
+++ b/drivers/i2c/algos/i2c-algo-bit.c
@@ -184,8 +184,9 @@ static int i2c_outb(struct i2c_adapter *i2c_adap, unsigned char c)
/* read ack: SDA should be pulled down by slave, or it may
* NAK (usually to report problems with the data we wrote).
+ * Report ACK if SDA is write-only.
*/
- ack = !getsda(adap); /* ack: sda is pulled low -> success */
+ ack = !adap->getsda || !getsda(adap); /* ack: sda is pulled low -> success */
bit_dbg(2, &i2c_adap->dev, "i2c_outb: 0x%02x %s\n", (int)c,
ack ? "A" : "NA");
@@ -203,6 +204,9 @@ static int i2c_inb(struct i2c_adapter *i2c_adap)
unsigned char indata = 0;
struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
+ if (!adap->getsda)
+ return -EOPNOTSUPP;
+
/* assert: scl is low */
sdahi(adap);
for (i = 0; i < 8; i++) {
@@ -232,6 +236,10 @@ static int test_bus(struct i2c_adapter *i2c_adap)
const char *name = i2c_adap->name;
int scl, sda, ret;
+ /* Testing not possible if both pins are write-only. */
+ if (adap->getscl == NULL && adap->getsda == NULL)
+ return 0;
+
if (adap->pre_xfer) {
ret = adap->pre_xfer(i2c_adap);
if (ret < 0)
@@ -670,8 +678,10 @@ static int __i2c_bit_add_bus(struct i2c_adapter *adap,
if (ret < 0)
return ret;
- /* Complain if SCL can't be read */
- if (bit_adap->getscl == NULL) {
+ if (bit_adap->getscl == NULL && bit_adap->getsda == NULL)
+ dev_info(&adap->dev, "I2C-like interface, SDA and SCL are write-only\n");
+ else if (bit_adap->getscl == NULL) {
+ /* Complain if SCL can't be read */
dev_warn(&adap->dev, "Not I2C compliant: can't read SCL\n");
dev_warn(&adap->dev, "Bus may be unreliable\n");
}
--
2.35.3
