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i2c: aspeed: Add multi-master use case support 

In multi-master environment, this driver's master cannot know
exactly when a peer master sends data to this driver's slave so
cases can be happened that this master tries sending data through
the master_xfer function but slave data from a peer master is still
being processed or slave xfer is started by a peer immediately
after it queues a master command. To support multi-master use cases
properly, this H/W provides arbitration in physical level and it
provides priority based command handling too to avoid conflicts in
multi-master environment, means that if a master and a slave events
happen at the same time, H/W will handle a higher priority event
first and a pending event will be handled when bus comes back to
the idle state.

To support this H/W feature properly, this patch adds the 'pending'
state of master and its handling code so that the pending master
xfer can be continued after slave operation properly.

Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com>
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
This commit is contained in:
Jae Hyun Yoo 2019-02-11 10:54:44 -08:00 committed by Wolfram Sang
parent bceb26bffe
commit 2e57b7cebb
1 changed files with 93 additions and 26 deletions
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119
drivers/i2c/busses/i2c-aspeed.c
View File

@ -117,6 +117,7 @@
enum aspeed_i2c_master_state {
ASPEED_I2C_MASTER_INACTIVE,
ASPEED_I2C_MASTER_PENDING,
ASPEED_I2C_MASTER_START,
ASPEED_I2C_MASTER_TX_FIRST,
ASPEED_I2C_MASTER_TX,
@ -126,12 +127,13 @@ enum aspeed_i2c_master_state {
};
enum aspeed_i2c_slave_state {
ASPEED_I2C_SLAVE_STOP,
ASPEED_I2C_SLAVE_INACTIVE,
ASPEED_I2C_SLAVE_START,
ASPEED_I2C_SLAVE_READ_REQUESTED,
ASPEED_I2C_SLAVE_READ_PROCESSED,
ASPEED_I2C_SLAVE_WRITE_REQUESTED,
ASPEED_I2C_SLAVE_WRITE_RECEIVED,
ASPEED_I2C_SLAVE_STOP,
};
struct aspeed_i2c_bus {
@ -156,6 +158,8 @@ struct aspeed_i2c_bus {
int cmd_err;
/* Protected only by i2c_lock_bus */
int master_xfer_result;
/* Multi-master */
bool multi_master;
#if IS_ENABLED(CONFIG_I2C_SLAVE)
struct i2c_client *slave;
enum aspeed_i2c_slave_state slave_state;
@ -251,7 +255,7 @@ static u32 aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
}
/* Slave is not currently active, irq was for someone else. */
if (bus->slave_state == ASPEED_I2C_SLAVE_STOP)
if (bus->slave_state == ASPEED_I2C_SLAVE_INACTIVE)
return irq_handled;
dev_dbg(bus->dev, "slave irq status 0x%08x, cmd 0x%08x\n",
@ -277,16 +281,15 @@ static u32 aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
irq_handled |= ASPEED_I2CD_INTR_NORMAL_STOP;
bus->slave_state = ASPEED_I2C_SLAVE_STOP;
}
if (irq_status & ASPEED_I2CD_INTR_TX_NAK) {
if (irq_status & ASPEED_I2CD_INTR_TX_NAK &&
bus->slave_state == ASPEED_I2C_SLAVE_READ_PROCESSED) {
irq_handled |= ASPEED_I2CD_INTR_TX_NAK;
bus->slave_state = ASPEED_I2C_SLAVE_STOP;
}
if (irq_status & ASPEED_I2CD_INTR_TX_ACK)
irq_handled |= ASPEED_I2CD_INTR_TX_ACK;
switch (bus->slave_state) {
case ASPEED_I2C_SLAVE_READ_REQUESTED:
if (irq_status & ASPEED_I2CD_INTR_TX_ACK)
if (unlikely(irq_status & ASPEED_I2CD_INTR_TX_ACK))
dev_err(bus->dev, "Unexpected ACK on read request.\n");
bus->slave_state = ASPEED_I2C_SLAVE_READ_PROCESSED;
i2c_slave_event(slave, I2C_SLAVE_READ_REQUESTED, &value);
@ -294,9 +297,12 @@ static u32 aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
writel(ASPEED_I2CD_S_TX_CMD, bus->base + ASPEED_I2C_CMD_REG);
break;
case ASPEED_I2C_SLAVE_READ_PROCESSED:
if (!(irq_status & ASPEED_I2CD_INTR_TX_ACK))
if (unlikely(!(irq_status & ASPEED_I2CD_INTR_TX_ACK))) {
dev_err(bus->dev,
"Expected ACK after processed read.\n");
break;
}
irq_handled |= ASPEED_I2CD_INTR_TX_ACK;
i2c_slave_event(slave, I2C_SLAVE_READ_PROCESSED, &value);
writel(value, bus->base + ASPEED_I2C_BYTE_BUF_REG);
writel(ASPEED_I2CD_S_TX_CMD, bus->base + ASPEED_I2C_CMD_REG);
@ -310,10 +316,15 @@ static u32 aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
break;
case ASPEED_I2C_SLAVE_STOP:
i2c_slave_event(slave, I2C_SLAVE_STOP, &value);
bus->slave_state = ASPEED_I2C_SLAVE_INACTIVE;
break;
case ASPEED_I2C_SLAVE_START:
/* Slave was just started. Waiting for the next event. */;
break;
default:
dev_err(bus->dev, "unhandled slave_state: %d\n",
dev_err(bus->dev, "unknown slave_state: %d\n",
bus->slave_state);
bus->slave_state = ASPEED_I2C_SLAVE_INACTIVE;
break;
}
@ -329,6 +340,17 @@ static void aspeed_i2c_do_start(struct aspeed_i2c_bus *bus)
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)
bus->master_state = ASPEED_I2C_MASTER_PENDING;
#endif /* CONFIG_I2C_SLAVE */
bus->buf_index = 0;
if (msg->flags & I2C_M_RD) {
@ -384,10 +406,6 @@ static u32 aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
bus->master_state = ASPEED_I2C_MASTER_INACTIVE;
irq_handled |= ASPEED_I2CD_INTR_BUS_RECOVER_DONE;
goto out_complete;
} else {
/* Master is not currently active, irq was for someone else. */
if (bus->master_state == ASPEED_I2C_MASTER_INACTIVE)
goto out_no_complete;
}
/*
@ -399,12 +417,33 @@ static u32 aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
if (ret) {
dev_dbg(bus->dev, "received error interrupt: 0x%08x\n",
irq_status);
bus->cmd_err = ret;
bus->master_state = ASPEED_I2C_MASTER_INACTIVE;
irq_handled |= (irq_status & ASPEED_I2CD_INTR_MASTER_ERRORS);
goto out_complete;
if (bus->master_state != ASPEED_I2C_MASTER_INACTIVE) {
bus->cmd_err = ret;
bus->master_state = ASPEED_I2C_MASTER_INACTIVE;
goto out_complete;
}
}
#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)
goto out_no_complete;
/* We are in an invalid state; reset bus to a known state. */
if (!bus->msgs) {
dev_err(bus->dev, "bus in unknown state. irq_status: 0x%x\n",
@ -423,6 +462,20 @@ static u32 aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
* then update the state and handle the new state below.
*/
if (bus->master_state == ASPEED_I2C_MASTER_START) {
#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.
*/
if (unlikely(irq_status & ASPEED_I2CD_INTR_SLAVE_MATCH)) {
bus->master_state = ASPEED_I2C_MASTER_PENDING;
dev_dbg(bus->dev,
"master goes pending due to a slave start\n");
goto out_no_complete;
}
#endif /* CONFIG_I2C_SLAVE */
if (unlikely(!(irq_status & ASPEED_I2CD_INTR_TX_ACK))) {
if (unlikely(!(irq_status & ASPEED_I2CD_INTR_TX_NAK))) {
bus->cmd_err = -ENXIO;
@ -566,7 +619,8 @@ static irqreturn_t aspeed_i2c_bus_irq(int irq, void *dev_id)
* interrupt bits. Each case needs to be handled using corresponding
* handlers depending on the current state.
*/
if (bus->master_state != ASPEED_I2C_MASTER_INACTIVE) {
if (bus->master_state != ASPEED_I2C_MASTER_INACTIVE &&
bus->master_state != ASPEED_I2C_MASTER_PENDING) {
irq_handled = aspeed_i2c_master_irq(bus, irq_remaining);
irq_remaining &= ~irq_handled;
if (irq_remaining)
@ -601,15 +655,16 @@ static int aspeed_i2c_master_xfer(struct i2c_adapter *adap,
{
struct aspeed_i2c_bus *bus = i2c_get_adapdata(adap);
unsigned long time_left, flags;
int ret = 0;
spin_lock_irqsave(&bus->lock, flags);
bus->cmd_err = 0;
/* If bus is busy, attempt recovery. We assume a single master
* environment.
*/
if (readl(bus->base + ASPEED_I2C_CMD_REG) & ASPEED_I2CD_BUS_BUSY_STS) {
/* If bus is busy in a single master environment, attempt recovery. */
if (!bus->multi_master &&
(readl(bus->base + ASPEED_I2C_CMD_REG) &
ASPEED_I2CD_BUS_BUSY_STS)) {
int ret;
spin_unlock_irqrestore(&bus->lock, flags);
ret = aspeed_i2c_recover_bus(bus);
if (ret)
@ -629,10 +684,20 @@ static int aspeed_i2c_master_xfer(struct i2c_adapter *adap,
time_left = wait_for_completion_timeout(&bus->cmd_complete,
bus->adap.timeout);
if (time_left == 0)
if (time_left == 0) {
/*
* If timed out and bus is still busy in a multi master
* environment, attempt recovery at here.
*/
if (bus->multi_master &&
(readl(bus->base + ASPEED_I2C_CMD_REG) &
ASPEED_I2CD_BUS_BUSY_STS))
aspeed_i2c_recover_bus(bus);
return -ETIMEDOUT;
else
return bus->master_xfer_result;
}
return bus->master_xfer_result;
}
static u32 aspeed_i2c_functionality(struct i2c_adapter *adap)
@ -672,7 +737,7 @@ static int aspeed_i2c_reg_slave(struct i2c_client *client)
__aspeed_i2c_reg_slave(bus, client->addr);
bus->slave = client;
bus->slave_state = ASPEED_I2C_SLAVE_STOP;
bus->slave_state = ASPEED_I2C_SLAVE_INACTIVE;
spin_unlock_irqrestore(&bus->lock, flags);
return 0;
@ -827,7 +892,9 @@ static int aspeed_i2c_init(struct aspeed_i2c_bus *bus,
if (ret < 0)
return ret;
if (!of_property_read_bool(pdev->dev.of_node, "multi-master"))
if (of_property_read_bool(pdev->dev.of_node, "multi-master"))
bus->multi_master = true;
else
fun_ctrl_reg |= ASPEED_I2CD_MULTI_MASTER_DIS;
/* Enable Master Mode */