Commit 1f0d9cbe authored by Jae Hyun Yoo's avatar Jae Hyun Yoo Committed by Wolfram Sang
Browse files

i2c: aspeed: fix master pending state handling 



In case of master pending state, it should not trigger a master
command, otherwise data could be corrupted because this H/W shares
the same data buffer for slave and master operations. It also means
that H/W command queue handling is unreliable because of the buffer
sharing issue. To fix this issue, it clears command queue if a
master command is queued in pending state to use S/W solution
instead of H/W command queue handling. Also, it refines restarting
mechanism of the pending master command.

Fixes: 2e57b7ce ("i2c: aspeed: Add multi-master use case support")
Signed-off-by: default avatarJae Hyun Yoo <jae.hyun.yoo@linux.intel.com>
Reviewed-by: default avatarBrendan Higgins <brendanhiggins@google.com>
Acked-by: default avatarJoel Stanley <joel@jms.id.au>
Tested-by: default avatarTao Ren <taoren@fb.com>
Signed-off-by: default avatarWolfram Sang <wsa@the-dreams.de>
parent 7d194c21

drivers/i2c/busses/i2c-aspeed.c

+34 −20
Original line number Diff line number Diff line
@@ -108,6 +108,12 @@ 
#define ASPEED_I2CD_S_TX_CMD				BIT(2)

#define ASPEED_I2CD_M_TX_CMD				BIT(1)

#define ASPEED_I2CD_M_START_CMD				BIT(0)

#define ASPEED_I2CD_MASTER_CMDS_MASK					       \

		(ASPEED_I2CD_M_STOP_CMD |				       \

		 ASPEED_I2CD_M_S_RX_CMD_LAST |				       \

		 ASPEED_I2CD_M_RX_CMD |					       \

		 ASPEED_I2CD_M_TX_CMD |					       \

		 ASPEED_I2CD_M_START_CMD)



/* 0x18 : I2CD Slave Device Address Register   */

#define ASPEED_I2CD_DEV_ADDR_MASK			GENMASK(6, 0)
@@ -336,18 +342,19 @@ static void aspeed_i2c_do_start(struct aspeed_i2c_bus *bus) 
	struct i2c_msg *msg = &bus->msgs[bus->msgs_index];

	u8 slave_addr = i2c_8bit_addr_from_msg(msg);



	bus->master_state = ASPEED_I2C_MASTER_START;



#if IS_ENABLED(CONFIG_I2C_SLAVE)

	/*

	 * If it's requested in the middle of a slave session, set the master

	 * state to 'pending' then H/W will continue handling this master

	 * command when the bus comes back to the idle state.

	 */

	if (bus->slave_state != ASPEED_I2C_SLAVE_INACTIVE)

	if (bus->slave_state != ASPEED_I2C_SLAVE_INACTIVE) {

		bus->master_state = ASPEED_I2C_MASTER_PENDING;

		return;

	}

#endif /* CONFIG_I2C_SLAVE */



	bus->master_state = ASPEED_I2C_MASTER_START;

	bus->buf_index = 0;



	if (msg->flags & I2C_M_RD) {
@@ -422,20 +429,6 @@ static u32 aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus, u32 irq_status) 
		}

	}



#if IS_ENABLED(CONFIG_I2C_SLAVE)

	/*

	 * A pending master command will be started by H/W when the bus comes

	 * back to idle state after completing a slave operation so change the

	 * master state from 'pending' to 'start' at here if slave is inactive.

	 */

	if (bus->master_state == ASPEED_I2C_MASTER_PENDING) {

		if (bus->slave_state != ASPEED_I2C_SLAVE_INACTIVE)

			goto out_no_complete;



		bus->master_state = ASPEED_I2C_MASTER_START;

	}

#endif /* CONFIG_I2C_SLAVE */



	/* Master is not currently active, irq was for someone else. */

	if (bus->master_state == ASPEED_I2C_MASTER_INACTIVE ||

	    bus->master_state == ASPEED_I2C_MASTER_PENDING)
@@ -462,11 +455,15 @@ static u32 aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus, u32 irq_status) 
#if IS_ENABLED(CONFIG_I2C_SLAVE)

		/*

		 * If a peer master starts a xfer immediately after it queues a

		 * master command, change its state to 'pending' then H/W will

		 * continue the queued master xfer just after completing the

		 * slave mode session.

		 * master command, clear the queued master command and change

		 * its state to 'pending'. To simplify handling of pending

		 * cases, it uses S/W solution instead of H/W command queue

		 * handling.

		 */

		if (unlikely(irq_status & ASPEED_I2CD_INTR_SLAVE_MATCH)) {

			writel(readl(bus->base + ASPEED_I2C_CMD_REG) &

				~ASPEED_I2CD_MASTER_CMDS_MASK,

			       bus->base + ASPEED_I2C_CMD_REG);

			bus->master_state = ASPEED_I2C_MASTER_PENDING;

			dev_dbg(bus->dev,

				"master goes pending due to a slave start\n");
@@ -629,6 +626,14 @@ static irqreturn_t aspeed_i2c_bus_irq(int irq, void *dev_id) 
			irq_handled |= aspeed_i2c_master_irq(bus,

							     irq_remaining);

	}



	/*

	 * Start a pending master command at here if a slave operation is

	 * completed.

	 */

	if (bus->master_state == ASPEED_I2C_MASTER_PENDING &&

	    bus->slave_state == ASPEED_I2C_SLAVE_INACTIVE)

		aspeed_i2c_do_start(bus);

#else

	irq_handled = aspeed_i2c_master_irq(bus, irq_remaining);

#endif /* CONFIG_I2C_SLAVE */
@@ -691,6 +696,15 @@ static int aspeed_i2c_master_xfer(struct i2c_adapter *adap, 
		     ASPEED_I2CD_BUS_BUSY_STS))

			aspeed_i2c_recover_bus(bus);



		/*

		 * If timed out and the state is still pending, drop the pending

		 * master command.

		 */

		spin_lock_irqsave(&bus->lock, flags);

		if (bus->master_state == ASPEED_I2C_MASTER_PENDING)

			bus->master_state = ASPEED_I2C_MASTER_INACTIVE;

		spin_unlock_irqrestore(&bus->lock, flags);



		return -ETIMEDOUT;

	}

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