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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: 2e57b7cebb ("i2c: aspeed: Add multi-master use case support")
Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com>
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
Acked-by: Joel Stanley <joel@jms.id.au>
Tested-by: Tao Ren <taoren@fb.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
This commit is contained in:
Jae Hyun Yoo 2019-10-09 14:20:34 -07:00 committed by Wolfram Sang
parent 7d194c2100
commit 1f0d9cbeec
1 changed files with 34 additions and 20 deletions
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54
drivers/i2c/busses/i2c-aspeed.c
View File

@ -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;
}