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SubjectRe: [PATCH i2c-next v6] i2c: aspeed: Handle master/slave combined irq events properly
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On 9/6/2018 10:26 AM, Brendan Higgins wrote:
> On Thu, Aug 23, 2018 at 3:58 PM Jae Hyun Yoo
> <jae.hyun.yoo@linux.intel.com> wrote:
>>
>> In most of cases, interrupt bits are set one by one but there are
>> also a lot of other cases that Aspeed I2C IP sends multiple
>> interrupt bits with combining master and slave events using a
>> single interrupt call. It happens much more in multi-master
>> environment than single-master. For an example, when master is
>> waiting for a NORMAL_STOP interrupt in its MASTER_STOP state,
>> SLAVE_MATCH and RX_DONE interrupts could come along with the
>> NORMAL_STOP in case of an another master immediately sends data
>> just after acquiring the bus. In this case, the NORMAL_STOP
>> interrupt should be handled by master_irq and the SLAVE_MATCH and
>> RX_DONE interrupts should be handled by slave_irq. This commit
>> modifies irq hadling logic to handle the master/slave combined
>> events properly.
>>
>> Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com>
>> ---
>> Changes since v5:
>> - Changed variable names in irq hanlders to represent proper meaning.
>> - Fixed an error printing message again to make it use the irq_handled variable.
>>
>> Changes since v4:
>> - Fixed an error printing message that handlers didn't handle all interrupts.
>>
>> Changes since v3:
>> - Fixed typos in a comment.
>>
>> Changes since v2:
>> - Changed the name of ASPEED_I2CD_INTR_ERRORS to ASPEED_I2CD_INTR_MASTER_ERRORS
>> - Removed a member irq_status from the struct aspeed_i2c_bus and changed
>> master_irq and slave_irq handlers to make them return status_ack.
>> - Added a comment to explain why it needs to try both irq handlers.
>>
>> Changes since v1:
>> - Fixed a grammar issue in commit message.
>> - Added a missing line feed character into a message printing.
>>
>> drivers/i2c/busses/i2c-aspeed.c | 131 ++++++++++++++++++--------------
>> 1 file changed, 76 insertions(+), 55 deletions(-)
>>
>> diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-aspeed.c
>> index a4f956c6d567..c258c4d9a4c0 100644
>> --- a/drivers/i2c/busses/i2c-aspeed.c
>> +++ b/drivers/i2c/busses/i2c-aspeed.c
>> @@ -82,6 +82,11 @@
>> #define ASPEED_I2CD_INTR_RX_DONE BIT(2)
>> #define ASPEED_I2CD_INTR_TX_NAK BIT(1)
>> #define ASPEED_I2CD_INTR_TX_ACK BIT(0)
>> +#define ASPEED_I2CD_INTR_MASTER_ERRORS \
>> + (ASPEED_I2CD_INTR_SDA_DL_TIMEOUT | \
>> + ASPEED_I2CD_INTR_SCL_TIMEOUT | \
>> + ASPEED_I2CD_INTR_ABNORMAL | \
>> + ASPEED_I2CD_INTR_ARBIT_LOSS)
>> #define ASPEED_I2CD_INTR_ALL \
>> (ASPEED_I2CD_INTR_SDA_DL_TIMEOUT | \
>> ASPEED_I2CD_INTR_BUS_RECOVER_DONE | \
>> @@ -227,32 +232,26 @@ static int aspeed_i2c_recover_bus(struct aspeed_i2c_bus *bus)
>> }
>>
>> #if IS_ENABLED(CONFIG_I2C_SLAVE)
>> -static bool aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus)
>> +static u32 aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
>> {
>> - u32 command, irq_status, status_ack = 0;
>> + u32 command, irq_handled = 0;
>> struct i2c_client *slave = bus->slave;
>> - bool irq_handled = true;
>> u8 value;
>>
>> - if (!slave) {
>> - irq_handled = false;
>> - goto out;
>> - }
>> + if (!slave)
>> + return 0;
>>
>> command = readl(bus->base + ASPEED_I2C_CMD_REG);
>> - irq_status = readl(bus->base + ASPEED_I2C_INTR_STS_REG);
>>
>> /* Slave was requested, restart state machine. */
>> if (irq_status & ASPEED_I2CD_INTR_SLAVE_MATCH) {
>> - status_ack |= ASPEED_I2CD_INTR_SLAVE_MATCH;
>> + irq_handled |= ASPEED_I2CD_INTR_SLAVE_MATCH;
>> bus->slave_state = ASPEED_I2C_SLAVE_START;
>> }
>>
>> /* Slave is not currently active, irq was for someone else. */
>> - if (bus->slave_state == ASPEED_I2C_SLAVE_STOP) {
>> - irq_handled = false;
>> - goto out;
>> - }
>> + if (bus->slave_state == ASPEED_I2C_SLAVE_STOP)
>> + return irq_handled;
>>
>> dev_dbg(bus->dev, "slave irq status 0x%08x, cmd 0x%08x\n",
>> irq_status, command);
>> @@ -269,31 +268,31 @@ static bool aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus)
>> bus->slave_state =
>> ASPEED_I2C_SLAVE_WRITE_REQUESTED;
>> }
>> - status_ack |= ASPEED_I2CD_INTR_RX_DONE;
>> + irq_handled |= ASPEED_I2CD_INTR_RX_DONE;
>> }
>>
>> /* Slave was asked to stop. */
>> if (irq_status & ASPEED_I2CD_INTR_NORMAL_STOP) {
>> - status_ack |= ASPEED_I2CD_INTR_NORMAL_STOP;
>> + irq_handled |= ASPEED_I2CD_INTR_NORMAL_STOP;
>> bus->slave_state = ASPEED_I2C_SLAVE_STOP;
>> }
>> if (irq_status & ASPEED_I2CD_INTR_TX_NAK) {
>> - status_ack |= ASPEED_I2CD_INTR_TX_NAK;
>> + 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)
>> 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);
>> writel(value, bus->base + ASPEED_I2C_BYTE_BUF_REG);
>> writel(ASPEED_I2CD_S_TX_CMD, bus->base + ASPEED_I2C_CMD_REG);
>> break;
>> case ASPEED_I2C_SLAVE_READ_PROCESSED:
>> - status_ack |= ASPEED_I2CD_INTR_TX_ACK;
>> if (!(irq_status & ASPEED_I2CD_INTR_TX_ACK))
>> dev_err(bus->dev,
>> "Expected ACK after processed read.\n");
>> @@ -317,13 +316,6 @@ static bool aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus)
>> break;
>> }
>>
>> - if (status_ack != irq_status)
>> - dev_err(bus->dev,
>> - "irq handled != irq. expected %x, but was %x\n",
>> - irq_status, status_ack);
>> - writel(status_ack, bus->base + ASPEED_I2C_INTR_STS_REG);
>> -
>> -out:
>> return irq_handled;
>> }
>> #endif /* CONFIG_I2C_SLAVE */
>> @@ -380,21 +372,21 @@ static int aspeed_i2c_is_irq_error(u32 irq_status)
>> return 0;
>> }
>>
>> -static bool aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus)
>> +static u32 aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
>> {
>> - u32 irq_status, status_ack = 0, command = 0;
>> + u32 irq_handled = 0, command = 0;
>> struct i2c_msg *msg;
>> u8 recv_byte;
>> int ret;
>>
>> - irq_status = readl(bus->base + ASPEED_I2C_INTR_STS_REG);
>> - /* Ack all interrupt bits. */
>> - writel(irq_status, bus->base + ASPEED_I2C_INTR_STS_REG);
>> -
>> if (irq_status & ASPEED_I2CD_INTR_BUS_RECOVER_DONE) {
>> bus->master_state = ASPEED_I2C_MASTER_INACTIVE;
>> - status_ack |= ASPEED_I2CD_INTR_BUS_RECOVER_DONE;
>> + 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;
>> }
>>
>> /*
>> @@ -403,19 +395,22 @@ static bool aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus)
>> * INACTIVE state.
>> */
>> ret = aspeed_i2c_is_irq_error(irq_status);
>> - if (ret < 0) {
>> + 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;
>> }
>>
>> /* We are in an invalid state; reset bus to a known state. */
>> if (!bus->msgs) {
>> - dev_err(bus->dev, "bus in unknown state\n");
>> + dev_err(bus->dev, "bus in unknown state. irq_status: 0x%x\n",
>> + irq_status);
>> bus->cmd_err = -EIO;
>> - if (bus->master_state != ASPEED_I2C_MASTER_STOP)
>> + if (bus->master_state != ASPEED_I2C_MASTER_STOP &&
>> + bus->master_state != ASPEED_I2C_MASTER_INACTIVE)
>> aspeed_i2c_do_stop(bus);
>> goto out_no_complete;
>> }
>> @@ -428,13 +423,18 @@ static bool aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus)
>> */
>> if (bus->master_state == ASPEED_I2C_MASTER_START) {
>> if (unlikely(!(irq_status & ASPEED_I2CD_INTR_TX_ACK))) {
>> + if (unlikely(!(irq_status & ASPEED_I2CD_INTR_TX_NAK))) {
>> + bus->cmd_err = -ENXIO;
>> + bus->master_state = ASPEED_I2C_MASTER_INACTIVE;
>> + goto out_complete;
>> + }
>> pr_devel("no slave present at %02x\n", msg->addr);
>> - status_ack |= ASPEED_I2CD_INTR_TX_NAK;
>> + irq_handled |= ASPEED_I2CD_INTR_TX_NAK;
>> bus->cmd_err = -ENXIO;
>> aspeed_i2c_do_stop(bus);
>> goto out_no_complete;
>> }
>> - status_ack |= ASPEED_I2CD_INTR_TX_ACK;
>> + irq_handled |= ASPEED_I2CD_INTR_TX_ACK;
>> if (msg->len == 0) { /* SMBUS_QUICK */
>> aspeed_i2c_do_stop(bus);
>> goto out_no_complete;
>> @@ -449,13 +449,13 @@ static bool aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus)
>> case ASPEED_I2C_MASTER_TX:
>> if (unlikely(irq_status & ASPEED_I2CD_INTR_TX_NAK)) {
>> dev_dbg(bus->dev, "slave NACKed TX\n");
>> - status_ack |= ASPEED_I2CD_INTR_TX_NAK;
>> + irq_handled |= ASPEED_I2CD_INTR_TX_NAK;
>> goto error_and_stop;
>> } else if (unlikely(!(irq_status & ASPEED_I2CD_INTR_TX_ACK))) {
>> dev_err(bus->dev, "slave failed to ACK TX\n");
>> goto error_and_stop;
>> }
>> - status_ack |= ASPEED_I2CD_INTR_TX_ACK;
>> + irq_handled |= ASPEED_I2CD_INTR_TX_ACK;
>> /* fallthrough intended */
>> case ASPEED_I2C_MASTER_TX_FIRST:
>> if (bus->buf_index < msg->len) {
>> @@ -478,7 +478,7 @@ static bool aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus)
>> dev_err(bus->dev, "master failed to RX\n");
>> goto error_and_stop;
>> }
>> - status_ack |= ASPEED_I2CD_INTR_RX_DONE;
>> + irq_handled |= ASPEED_I2CD_INTR_RX_DONE;
>>
>> recv_byte = readl(bus->base + ASPEED_I2C_BYTE_BUF_REG) >> 8;
>> msg->buf[bus->buf_index++] = recv_byte;
>> @@ -506,11 +506,13 @@ static bool aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus)
>> goto out_no_complete;
>> case ASPEED_I2C_MASTER_STOP:
>> if (unlikely(!(irq_status & ASPEED_I2CD_INTR_NORMAL_STOP))) {
>> - dev_err(bus->dev, "master failed to STOP\n");
>> + dev_err(bus->dev,
>> + "master failed to STOP. irq_status:0x%x\n",
>> + irq_status);
>> bus->cmd_err = -EIO;
>> /* Do not STOP as we have already tried. */
>> } else {
>> - status_ack |= ASPEED_I2CD_INTR_NORMAL_STOP;
>> + irq_handled |= ASPEED_I2CD_INTR_NORMAL_STOP;
>> }
>>
>> bus->master_state = ASPEED_I2C_MASTER_INACTIVE;
>> @@ -540,33 +542,52 @@ static bool aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus)
>> bus->master_xfer_result = bus->msgs_index + 1;
>> complete(&bus->cmd_complete);
>> out_no_complete:
>> - if (irq_status != status_ack)
>> - dev_err(bus->dev,
>> - "irq handled != irq. expected 0x%08x, but was 0x%08x\n",
>> - irq_status, status_ack);
>> - return !!irq_status;
>> + return irq_handled;
>> }
>>
>> static irqreturn_t aspeed_i2c_bus_irq(int irq, void *dev_id)
>> {
>> struct aspeed_i2c_bus *bus = dev_id;
>> - bool ret;
>> + u32 irq_received, irq_remaining, irq_handled;
>>
>> spin_lock(&bus->lock);
>> + irq_received = readl(bus->base + ASPEED_I2C_INTR_STS_REG);
>> + irq_remaining = irq_received;
>>
>> #if IS_ENABLED(CONFIG_I2C_SLAVE)
>> - if (aspeed_i2c_slave_irq(bus)) {
>> - dev_dbg(bus->dev, "irq handled by slave.\n");
>> - ret = true;
>> - goto out;
>> + /*
>> + * In most cases, interrupt bits will be set one by one, although
>> + * multiple interrupt bits could be set at the same time. It's also
>> + * possible that master interrupt bits could be set along with slave
>> + * interrupt bits. Each case needs to be handled using corresponding
>> + * handlers depending on the current state.
>> + */
>> + if (bus->master_state != ASPEED_I2C_MASTER_INACTIVE) {
>> + irq_handled = aspeed_i2c_master_irq(bus, irq_remaining);
>> + irq_remaining &= ~irq_handled;
>> + if (irq_remaining)
>> + irq_handled |= aspeed_i2c_slave_irq(bus, irq_remaining);
>> + } else {
>> + irq_handled = aspeed_i2c_slave_irq(bus, irq_remaining);
>> + irq_remaining &= ~irq_handled;
>> + if (irq_remaining)
>> + irq_handled |= aspeed_i2c_master_irq(bus,
>> + irq_remaining);
>> }
>> +#else
>> + irq_handled = aspeed_i2c_master_irq(bus, irq_remaining);
>> #endif /* CONFIG_I2C_SLAVE */
>>
>> - ret = aspeed_i2c_master_irq(bus);
>> + irq_remaining &= ~irq_handled;
>> + if (irq_remaining)
>> + dev_err(bus->dev,
>> + "irq handled != irq. expected 0x%08x, but was 0x%08x\n",
>> + irq_received, irq_handled);
>>
>> -out:
>> + /* Ack all interrupt bits. */
>> + writel(irq_received, bus->base + ASPEED_I2C_INTR_STS_REG);
>> spin_unlock(&bus->lock);
>> - return ret ? IRQ_HANDLED : IRQ_NONE;
>> + return irq_remaining ? IRQ_NONE : IRQ_HANDLED;
>> }
>>
>> static int aspeed_i2c_master_xfer(struct i2c_adapter *adap,
>> --
>> 2.18.0
>>
>
> Looks awesome! Thanks!
>
> Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
>

Thanks a lot for your review Brendan!

-Jae

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