[PATCH v3 2/3] i2c: algo: bit: allow getsda to be NULL

Heiner Kallweit
2023-01-15T10:18:50Z

This is in preparation of supporting write-only SDA in i2c-gpio.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
---
v3:
- check for adap->getsda in readbytes()
- align warning message level for info on missing getscl/getsda
---
drivers/i2c/algos/i2c-algo-bit.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/algos/i2c-algo-bit.c b/drivers/i2c/algos/i2c-algo-bit.c
index fc90293af..a1b822723 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).
+ * Always 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");

@@ -232,6 +233,10 @@ 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)
@@ -420,6 +425,10 @@ static int readbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
unsigned char *temp = msg->buf;
int count = msg->len;
const unsigned flags = msg->flags;
+ struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
+
+ if (!adap->getsda)
+ return -EOPNOTSUPP;

while (count > 0) {
inval = i2c_inb(i2c_adap);
@@ -670,8 +679,11 @@ 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->getsda == NULL)
+ dev_warn(&adap->dev, "Not I2C compliant: can't read SDA\n");
+
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");
}
--
2.39.0