[PATCH i2c-next v4] i2c: aspeed: Handle master/slave combined irq events properly

Jae Hyun Yoo jae.hyun.yoo at linux.intel.com
Fri Aug 24 04:29:27 AEST 2018


Hi Brendan,

On 8/22/2018 11:46 PM, Brendan Higgins wrote:
> On Mon, Aug 20, 2018 at 1:16 PM Jae Hyun Yoo
> <jae.hyun.yoo at 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 at linux.intel.com>
>> ---
>> 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 | 110 +++++++++++++++++++-------------
>>   1 file changed, 65 insertions(+), 45 deletions(-)
>>
>> diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-aspeed.c
>> index a4f956c6d567..09eb4a9b355c 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 |                           \
>> @@ -227,20 +232,16 @@ 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, status_ack = 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) {
>> @@ -249,10 +250,8 @@ static bool aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus)
>>          }
>>
>>          /* 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 status_ack;
>>
>>          dev_dbg(bus->dev, "slave irq status 0x%08x, cmd 0x%08x\n",
>>                  irq_status, command);
>> @@ -281,19 +280,19 @@ static bool aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus)
>>                  status_ack |= ASPEED_I2CD_INTR_TX_NAK;
>>                  bus->slave_state = ASPEED_I2C_SLAVE_STOP;
>>          }
>> +       if (irq_status & ASPEED_I2CD_INTR_TX_ACK)
>> +               status_ack |= 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");
>> @@ -317,14 +316,7 @@ 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;
>> +       return status_ack;
>>   }
>>   #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 status_ack = 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;
>>                  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;
>> +               status_ack |= (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;
>>          }
>> @@ -428,6 +423,11 @@ 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;
>>                          bus->cmd_err = -ENXIO;
>> @@ -506,7 +506,9 @@ 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 {
>> @@ -540,33 +542,51 @@ 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 status_ack;
>>   }
>>
>>   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_status, irq_acked;
>>
>>          spin_lock(&bus->lock);
>> +       irq_received = readl(bus->base + ASPEED_I2C_INTR_STS_REG);
>> +       irq_status = 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_acked = aspeed_i2c_master_irq(bus, irq_status);
>> +               irq_status &= ~irq_acked;
>> +               if (irq_status)
>> +                       irq_acked = aspeed_i2c_slave_irq(bus, irq_status);
>> +       } else {
>> +               irq_acked = aspeed_i2c_slave_irq(bus, irq_status);
>> +               irq_status &= ~irq_acked;
>> +               if (irq_status)
>> +                       irq_acked = aspeed_i2c_master_irq(bus, irq_status);
>>          }
>> +#else
>> +       irq_acked = aspeed_i2c_master_irq(bus, irq_status);
>>   #endif /* CONFIG_I2C_SLAVE */
>>
>> -       ret = aspeed_i2c_master_irq(bus);
>> +       irq_status &= ~irq_acked;
>> +       if (irq_status)
>> +               dev_err(bus->dev,
>> +                       "irq handled != irq. expected 0x%08x, but was 0x%08x\n",
>> +                       irq_received, irq_received ^ irq_status);
> 
> I think you want to use `irq_acked` here.
> 

Yes, right. I'll fix the message printing. Thanks for your pointing it out.

>>
>> -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_status ? IRQ_NONE : IRQ_HANDLED;
>>   }
>>
>>   static int aspeed_i2c_master_xfer(struct i2c_adapter *adap,
>> --
>> 2.18.0
>>
> 
> One minor issue and then I think we are good to go!
> 
> Also, sorry about not reviewing your last patch. I missed it apparently.
> 
> Feel free to mark the next patch "Reviewed-by: Brendan Higgins
> <brendanhiggins at google.com>"
> 
> Cheers
> 

Thanks a lot for your review. I really appreciate it. Will submit the v5 
patch soon.

Jae


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