diff mbox series

[v9,3/3] i2c: aspeed: Assert NAK when slave is busy

Message ID 20220929080326.752907-4-quan@os.amperecomputing.com
State Superseded
Headers show
Series Add SSIF BMC driver | expand

Commit Message

Quan Nguyen Sept. 29, 2022, 8:03 a.m. UTC 
On I2C_SLAVE_WRITE_REQUESTED event, Slave already ACK'ed on the address
phase. But as the backend driver is busy and unable to process any
request from Master, issue RxCmdLast for Slave to auto send NACK on
next incoming byte.

Signed-off-by: Quan Nguyen <quan@os.amperecomputing.com>
---
v9:
  + Update commit message and add comment to explain
    the effect of issuing RxCmdLast when Slave busy [Quan]

v7 -> v8:
  + None

v6:
  + New introduced in v6                            [Quan]

 drivers/i2c/busses/i2c-aspeed.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

Comments

Wolfram Sang Oct. 1, 2022, 10:55 p.m. UTC | #1 
> +		if (ret == -EBUSY)

Since we documented this:

"+  'ret': 0 if the backend is ready, otherwise some errno"

the code above should be '(ret < 0)'
Quan Nguyen Oct. 3, 2022, 2:06 a.m. UTC | #2 
On 02/10/2022 05:55, Wolfram Sang wrote:
> 
>> +		if (ret == -EBUSY)
> 
> Since we documented this:
> 
> "+  'ret': 0 if the backend is ready, otherwise some errno"
> 
> the code above should be '(ret < 0)'
> 

Will update.
Thanks a lot for the review.

- Quan
diff mbox series

Patch

diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-aspeed.c
index 185dedfebbac..3d70f1ce6c6a 100644
--- a/drivers/i2c/busses/i2c-aspeed.c
+++ b/drivers/i2c/busses/i2c-aspeed.c
@@ -244,6 +244,7 @@  static u32 aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
 	u32 command, irq_handled = 0;
 	struct i2c_client *slave = bus->slave;
 	u8 value;
+	int ret;
 
 	if (!slave)
 		return 0;
@@ -311,7 +312,13 @@  static u32 aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
 		break;
 	case ASPEED_I2C_SLAVE_WRITE_REQUESTED:
 		bus->slave_state = ASPEED_I2C_SLAVE_WRITE_RECEIVED;
-		i2c_slave_event(slave, I2C_SLAVE_WRITE_REQUESTED, &value);
+		ret = i2c_slave_event(slave, I2C_SLAVE_WRITE_REQUESTED, &value);
+		/*
+		 * Slave ACK's on this address phase already but as the backend driver insists it
+		 * is busy, turn on RxCmdLast for Slave to NACK on the next Rx byte.
+		 */
+		if (ret == -EBUSY)
+			writel(ASPEED_I2CD_M_S_RX_CMD_LAST, bus->base + ASPEED_I2C_CMD_REG);
 		break;
 	case ASPEED_I2C_SLAVE_WRITE_RECEIVED:
 		i2c_slave_event(slave, I2C_SLAVE_WRITE_RECEIVED, &value);