i2c: img-scb: support I2C_M_IGNORE_NAK
This commit adds support for the I2C_M_IGNORE_NAK protocol
modification.
Such behaviour can only be implemented in atomic mode. So, if a
transaction contains a message with such flag the drivers
switches to atomic mode. The implementation consists simply in
treating NAKs as ACKs.
Signed-off-by: Sifan Naeem <sifan.naeem@imgtec.com>
Acked-by: James Hogan <james.hogan@imgtec.com>
Reviewed-by: James Hartley <james.hartley@imgtec.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
diff --git a/drivers/i2c/busses/i2c-img-scb.c b/drivers/i2c/busses/i2c-img-scb.c
index 3795fe1..c92bcf7 100644
--- a/drivers/i2c/busses/i2c-img-scb.c
+++ b/drivers/i2c/busses/i2c-img-scb.c
@@ -750,7 +750,9 @@
next_cmd = CMD_RET_ACK;
break;
case CMD_RET_ACK:
- if (i2c->line_status & LINESTAT_ACK_DET) {
+ if (i2c->line_status & LINESTAT_ACK_DET ||
+ (i2c->line_status & LINESTAT_NACK_DET &&
+ i2c->msg.flags & I2C_M_IGNORE_NAK)) {
if (i2c->msg.len == 0) {
next_cmd = CMD_GEN_STOP;
} else if (i2c->msg.flags & I2C_M_RD) {
@@ -1017,20 +1019,23 @@
return -EIO;
for (i = 0; i < num; i++) {
- if (likely(msgs[i].len))
- continue;
/*
* 0 byte reads are not possible because the slave could try
* and pull the data line low, preventing a stop bit.
*/
- if (unlikely(msgs[i].flags & I2C_M_RD))
+ if (!msgs[i].len && msgs[i].flags & I2C_M_RD)
return -EIO;
/*
* 0 byte writes are possible and used for probing, but we
* cannot do them in automatic mode, so use atomic mode
* instead.
+ *
+ * Also, the I2C_M_IGNORE_NAK mode can only be implemented
+ * in atomic mode.
*/
- atomic = true;
+ if (!msgs[i].len ||
+ (msgs[i].flags & I2C_M_IGNORE_NAK))
+ atomic = true;
}
ret = clk_prepare_enable(i2c->scb_clk);