| Message ID | 20201011182254.17776-6-rayagonda.kokatanur@broadcom.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | fix iproc driver to handle master read request | expand |
On Sun, 11 Oct 2020 23:52:53 +0530, Rayagonda Kokatanur wrote: > --- a/drivers/i2c/busses/i2c-bcm-iproc.c > +++ b/drivers/i2c/busses/i2c-bcm-iproc.c > > - } else if (status & BIT(IS_S_RD_EVENT_SHIFT)) { > - /* Start of SMBUS for Master Read */ > + I2C_SLAVE_WRITE_REQUESTED, &rx_data); > + iproc_i2c->rx_start_rcvd = true; > + iproc_i2c->slave_read_complete = false; > + } else if (rx_status == I2C_SLAVE_RX_DATA && > + iproc_i2c->rx_start_rcvd) { > + /* Middle of SMBUS Master write */ > i2c_slave_event(iproc_i2c->slave, > - I2C_SLAVE_READ_REQUESTED, &value); > - iproc_i2c_wr_reg(iproc_i2c, S_TX_OFFSET, value); > + I2C_SLAVE_WRITE_RECEIVED, &rx_data); > + } else if (rx_status == I2C_SLAVE_RX_END && > + iproc_i2c->rx_start_rcvd) { > + /* End of SMBUS Master write */ > + if (iproc_i2c->slave_rx_only) > + i2c_slave_event(iproc_i2c->slave, > + I2C_SLAVE_WRITE_RECEIVED, > + &rx_data); > + > + i2c_slave_event(iproc_i2c->slave, I2C_SLAVE_STOP, > + &rx_data); > + } else if (rx_status == I2C_SLAVE_RX_FIFO_EMPTY) { > + iproc_i2c->rx_start_rcvd = false; > + iproc_i2c->slave_read_complete = true; > + break; > + } > > - val = BIT(S_CMD_START_BUSY_SHIFT); > - iproc_i2c_wr_reg(iproc_i2c, S_CMD_OFFSET, val); > + rx_bytes++; rx_bytes should be incremented only along with I2C_SLAVE_WRITE_RECEIVED event? > > +static bool bcm_iproc_i2c_slave_isr(struct bcm_iproc_i2c_dev *iproc_i2c, > + u32 status) > +{ > + u32 val; > + u8 value; > + > + /* > + * Slave events in case of master-write, master-write-read and, > + * master-read > + * > + * Master-write : only IS_S_RX_EVENT_SHIFT event > + * Master-write-read: both IS_S_RX_EVENT_SHIFT and IS_S_RD_EVENT_SHIFT > + * events > + * Master-read : both IS_S_RX_EVENT_SHIFT and IS_S_RD_EVENT_SHIFT > + * events or only IS_S_RD_EVENT_SHIFT > + */ > + if (status & BIT(IS_S_RX_EVENT_SHIFT) || > + status & BIT(IS_S_RD_EVENT_SHIFT)) { > + /* disable slave interrupts */ > + val = iproc_i2c_rd_reg(iproc_i2c, IE_OFFSET); > + val &= ~iproc_i2c->slave_int_mask; > + iproc_i2c_wr_reg(iproc_i2c, IE_OFFSET, val); > + > + if (status & BIT(IS_S_RD_EVENT_SHIFT)) > + /* Master-write-read request */ > + iproc_i2c->slave_rx_only = false; > + else > + /* Master-write request only */ > + iproc_i2c->slave_rx_only = true; > + > + /* schedule tasklet to read data later */ > + tasklet_schedule(&iproc_i2c->slave_rx_tasklet); > + > + /* clear only IS_S_RX_EVENT_SHIFT interrupt */ > + iproc_i2c_wr_reg(iproc_i2c, IS_OFFSET, > + BIT(IS_S_RX_EVENT_SHIFT)); > Both tasklet and isr are writing to status (IS_OFFSET) reg. The tasklet seems to be batching up rx fifo reads because of time-sensitive Master-write-read transaction? Linux I2C framework is byte interface anyway. Can the need to batch reads be avoided by setting slave rx threshold for interrupt (S_FIFO_RX_THLD) to 1-byte? Also, wouldn't tasklets be susceptible to other interrupts? If fifo reads have to be batched up, can it be changed to threaded irq?
On Wed, Oct 14, 2020 at 8:50 AM Dhananjay Phadke <dphadke@linux.microsoft.com> wrote: > > On Sun, 11 Oct 2020 23:52:53 +0530, Rayagonda Kokatanur wrote: > > --- a/drivers/i2c/busses/i2c-bcm-iproc.c > > +++ b/drivers/i2c/busses/i2c-bcm-iproc.c > > > > - } else if (status & BIT(IS_S_RD_EVENT_SHIFT)) { > > - /* Start of SMBUS for Master Read */ > > + I2C_SLAVE_WRITE_REQUESTED, &rx_data); > > + iproc_i2c->rx_start_rcvd = true; > > + iproc_i2c->slave_read_complete = false; > > + } else if (rx_status == I2C_SLAVE_RX_DATA && > > + iproc_i2c->rx_start_rcvd) { > > + /* Middle of SMBUS Master write */ > > i2c_slave_event(iproc_i2c->slave, > > - I2C_SLAVE_READ_REQUESTED, &value); > > - iproc_i2c_wr_reg(iproc_i2c, S_TX_OFFSET, value); > > + I2C_SLAVE_WRITE_RECEIVED, &rx_data); > > + } else if (rx_status == I2C_SLAVE_RX_END && > > + iproc_i2c->rx_start_rcvd) { > > + /* End of SMBUS Master write */ > > + if (iproc_i2c->slave_rx_only) > > + i2c_slave_event(iproc_i2c->slave, > > + I2C_SLAVE_WRITE_RECEIVED, > > + &rx_data); > > + > > + i2c_slave_event(iproc_i2c->slave, I2C_SLAVE_STOP, > > + &rx_data); > > + } else if (rx_status == I2C_SLAVE_RX_FIFO_EMPTY) { > > + iproc_i2c->rx_start_rcvd = false; > > + iproc_i2c->slave_read_complete = true; > > + break; > > + } > > > > - val = BIT(S_CMD_START_BUSY_SHIFT); > > - iproc_i2c_wr_reg(iproc_i2c, S_CMD_OFFSET, val); > > + rx_bytes++; > > rx_bytes should be incremented only along with I2C_SLAVE_WRITE_RECEIVED event? It should be incremented in both I2C_SLAVE_WRITE_REQUESTED and I2C_SLAVE_WRITE_RECEIVED cases because in both cases it is reading valid bytes from rx fifo. > > > > > +static bool bcm_iproc_i2c_slave_isr(struct bcm_iproc_i2c_dev *iproc_i2c, > > + u32 status) > > +{ > > + u32 val; > > + u8 value; > > + > > + /* > > + * Slave events in case of master-write, master-write-read and, > > + * master-read > > + * > > + * Master-write : only IS_S_RX_EVENT_SHIFT event > > + * Master-write-read: both IS_S_RX_EVENT_SHIFT and IS_S_RD_EVENT_SHIFT > > + * events > > + * Master-read : both IS_S_RX_EVENT_SHIFT and IS_S_RD_EVENT_SHIFT > > + * events or only IS_S_RD_EVENT_SHIFT > > + */ > > + if (status & BIT(IS_S_RX_EVENT_SHIFT) || > > + status & BIT(IS_S_RD_EVENT_SHIFT)) { > > + /* disable slave interrupts */ > > + val = iproc_i2c_rd_reg(iproc_i2c, IE_OFFSET); > > + val &= ~iproc_i2c->slave_int_mask; > > + iproc_i2c_wr_reg(iproc_i2c, IE_OFFSET, val); > > + > > + if (status & BIT(IS_S_RD_EVENT_SHIFT)) > > + /* Master-write-read request */ > > + iproc_i2c->slave_rx_only = false; > > + else > > + /* Master-write request only */ > > + iproc_i2c->slave_rx_only = true; > > + > > + /* schedule tasklet to read data later */ > > + tasklet_schedule(&iproc_i2c->slave_rx_tasklet); > > + > > + /* clear only IS_S_RX_EVENT_SHIFT interrupt */ > > + iproc_i2c_wr_reg(iproc_i2c, IS_OFFSET, > > + BIT(IS_S_RX_EVENT_SHIFT)); > > > > Both tasklet and isr are writing to status (IS_OFFSET) reg. > > The tasklet seems to be batching up rx fifo reads because of time-sensitive > Master-write-read transaction? Linux I2C framework is byte interface anyway. > Can the need to batch reads be avoided by setting slave rx threshold for > interrupt (S_FIFO_RX_THLD) to 1-byte? To process more data with a single interrupt we are batching up rx fifo reads. This will reduce the number of interrupts. Also to avoid tasklet running more time (20us) we have a threshold of 10 bytes for batching read. This is a better/optimised approach than reading single byte data per interrupt. > > Also, wouldn't tasklets be susceptible to other interrupts? If fifo reads > have to be batched up, can it be changed to threaded irq? tasklets have higher priority than threaded irq, since i2c is time sensitive so using a tasklet is preferred over threaded irq. Best regards, Rayagonda > >
On 10/13/2020 10:12 PM, Rayagonda Kokatanur wrote: > > > On Wed, Oct 14, 2020 at 8:50 AM Dhananjay Phadke > <dphadke@linux.microsoft.com <mailto:dphadke@linux.microsoft.com>> wrote: > > On Sun, 11 Oct 2020 23:52:53 +0530, Rayagonda Kokatanur wrote: > > --- a/drivers/i2c/busses/i2c-bcm-iproc.c > > +++ b/drivers/i2c/busses/i2c-bcm-iproc.c > > > > - } else if (status & BIT(IS_S_RD_EVENT_SHIFT)) { > > - /* Start of SMBUS for Master Read */ > > + I2C_SLAVE_WRITE_REQUESTED, > &rx_data); > > + iproc_i2c->rx_start_rcvd = true; > > + iproc_i2c->slave_read_complete = false; > > + } else if (rx_status == I2C_SLAVE_RX_DATA && > > + iproc_i2c->rx_start_rcvd) { > > + /* Middle of SMBUS Master write */ > > i2c_slave_event(iproc_i2c->slave, > > - I2C_SLAVE_READ_REQUESTED, > &value); > > - iproc_i2c_wr_reg(iproc_i2c, S_TX_OFFSET, value); > > + I2C_SLAVE_WRITE_RECEIVED, > &rx_data); > > + } else if (rx_status == I2C_SLAVE_RX_END && > > + iproc_i2c->rx_start_rcvd) { > > + /* End of SMBUS Master write */ > > + if (iproc_i2c->slave_rx_only) > > + i2c_slave_event(iproc_i2c->slave, > > + > I2C_SLAVE_WRITE_RECEIVED, > > + &rx_data); > > + > > + i2c_slave_event(iproc_i2c->slave, > I2C_SLAVE_STOP, > > + &rx_data); > > + } else if (rx_status == I2C_SLAVE_RX_FIFO_EMPTY) { > > + iproc_i2c->rx_start_rcvd = false; > > + iproc_i2c->slave_read_complete = true; > > + break; > > + } > > > > - val = BIT(S_CMD_START_BUSY_SHIFT); > > - iproc_i2c_wr_reg(iproc_i2c, S_CMD_OFFSET, val); > > + rx_bytes++; > > rx_bytes should be incremented only along with > I2C_SLAVE_WRITE_RECEIVED event? > > > It should be incremented in both I2C_SLAVE_WRITE_REQUESTED and > I2C_SLAVE_WRITE_RECEIVED cases because in both case it is reading valid > bytes from rx fifo. > > > > > > +static bool bcm_iproc_i2c_slave_isr(struct bcm_iproc_i2c_dev > *iproc_i2c, > > + u32 status) > > +{ > > + u32 val; > > + u8 value; > > + > > + /* > > + * Slave events in case of master-write, master-write-read and, > > + * master-read > > + * > > + * Master-write : only IS_S_RX_EVENT_SHIFT event > > + * Master-write-read: both IS_S_RX_EVENT_SHIFT and > IS_S_RD_EVENT_SHIFT > > + * events > > + * Master-read : both IS_S_RX_EVENT_SHIFT and > IS_S_RD_EVENT_SHIFT > > + * events or only IS_S_RD_EVENT_SHIFT > > + */ > > + if (status & BIT(IS_S_RX_EVENT_SHIFT) || > > + status & BIT(IS_S_RD_EVENT_SHIFT)) { > > + /* disable slave interrupts */ > > + val = iproc_i2c_rd_reg(iproc_i2c, IE_OFFSET); > > + val &= ~iproc_i2c->slave_int_mask; > > + iproc_i2c_wr_reg(iproc_i2c, IE_OFFSET, val); > > + > > + if (status & BIT(IS_S_RD_EVENT_SHIFT)) > > + /* Master-write-read request */ > > + iproc_i2c->slave_rx_only = false; > > + else > > + /* Master-write request only */ > > + iproc_i2c->slave_rx_only = true; > > + > > + /* schedule tasklet to read data later */ > > + tasklet_schedule(&iproc_i2c->slave_rx_tasklet); > > + > > + /* clear only IS_S_RX_EVENT_SHIFT interrupt */ > > + iproc_i2c_wr_reg(iproc_i2c, IS_OFFSET, > > + BIT(IS_S_RX_EVENT_SHIFT)); > > > > Both tasklet and isr are writing to status (IS_OFFSET) reg. > > > Yes this is required. > > For ex, If IS_S_RD_EVENT_SHIFT interrupt, this should be cleared once > the driver completes reading all data from rx fifo. > After this the driver can start sending data to master. > If both tasklet and isr are accessing the IS_OFFSET register, don't you need lock protection against race condition? That is, ISR can interrupt tasklet. > > > The tasklet seems to be batching up rx fifo reads because of > time-sensitive > Master-write-read transaction? Linux I2C framework is byte interface > anyway. > Can the need to batch reads be avoided by setting slave rx threshold for > interrupt (S_FIFO_RX_THLD) to 1-byte? > > > To process more data with a single interrupt we are batching up rx fifo > reads. > This will reduce the number of interrupts. > > Also to avoid tasklet running more time (20us) we have a threshold of 10 > bytes for batching read. > This is a better/optimised approach than reading single byte data per > interrupt. > > > Also, wouldn't tasklets be susceptible to other interrupts? If fifo > reads > have to be batched up, can it be changed to threaded irq? > > > tasklets have higher priority than threaded irq, since i2c is time > sensitive so using a tasklet is preferred over threaded irq. >
On Fri, Oct 23, 2020 at 10:56 PM Ray Jui <ray.jui@broadcom.com> wrote: > > > > On 10/13/2020 10:12 PM, Rayagonda Kokatanur wrote: > > > > > > On Wed, Oct 14, 2020 at 8:50 AM Dhananjay Phadke > > <dphadke@linux.microsoft.com <mailto:dphadke@linux.microsoft.com>> wrote: > > > > On Sun, 11 Oct 2020 23:52:53 +0530, Rayagonda Kokatanur wrote: > > > --- a/drivers/i2c/busses/i2c-bcm-iproc.c > > > +++ b/drivers/i2c/busses/i2c-bcm-iproc.c > > > > > > - } else if (status & BIT(IS_S_RD_EVENT_SHIFT)) { > > > - /* Start of SMBUS for Master Read */ > > > + I2C_SLAVE_WRITE_REQUESTED, > > &rx_data); > > > + iproc_i2c->rx_start_rcvd = true; > > > + iproc_i2c->slave_read_complete = false; > > > + } else if (rx_status == I2C_SLAVE_RX_DATA && > > > + iproc_i2c->rx_start_rcvd) { > > > + /* Middle of SMBUS Master write */ > > > i2c_slave_event(iproc_i2c->slave, > > > - I2C_SLAVE_READ_REQUESTED, > > &value); > > > - iproc_i2c_wr_reg(iproc_i2c, S_TX_OFFSET, value); > > > + I2C_SLAVE_WRITE_RECEIVED, > > &rx_data); > > > + } else if (rx_status == I2C_SLAVE_RX_END && > > > + iproc_i2c->rx_start_rcvd) { > > > + /* End of SMBUS Master write */ > > > + if (iproc_i2c->slave_rx_only) > > > + i2c_slave_event(iproc_i2c->slave, > > > + > > I2C_SLAVE_WRITE_RECEIVED, > > > + &rx_data); > > > + > > > + i2c_slave_event(iproc_i2c->slave, > > I2C_SLAVE_STOP, > > > + &rx_data); > > > + } else if (rx_status == I2C_SLAVE_RX_FIFO_EMPTY) { > > > + iproc_i2c->rx_start_rcvd = false; > > > + iproc_i2c->slave_read_complete = true; > > > + break; > > > + } > > > > > > - val = BIT(S_CMD_START_BUSY_SHIFT); > > > - iproc_i2c_wr_reg(iproc_i2c, S_CMD_OFFSET, val); > > > + rx_bytes++; > > > > rx_bytes should be incremented only along with > > I2C_SLAVE_WRITE_RECEIVED event? > > > > > > It should be incremented in both I2C_SLAVE_WRITE_REQUESTED and > > I2C_SLAVE_WRITE_RECEIVED cases because in both case it is reading valid > > bytes from rx fifo. > > > > > > > > > > +static bool bcm_iproc_i2c_slave_isr(struct bcm_iproc_i2c_dev > > *iproc_i2c, > > > + u32 status) > > > +{ > > > + u32 val; > > > + u8 value; > > > + > > > + /* > > > + * Slave events in case of master-write, master-write-read and, > > > + * master-read > > > + * > > > + * Master-write : only IS_S_RX_EVENT_SHIFT event > > > + * Master-write-read: both IS_S_RX_EVENT_SHIFT and > > IS_S_RD_EVENT_SHIFT > > > + * events > > > + * Master-read : both IS_S_RX_EVENT_SHIFT and > > IS_S_RD_EVENT_SHIFT > > > + * events or only IS_S_RD_EVENT_SHIFT > > > + */ > > > + if (status & BIT(IS_S_RX_EVENT_SHIFT) || > > > + status & BIT(IS_S_RD_EVENT_SHIFT)) { > > > + /* disable slave interrupts */ > > > + val = iproc_i2c_rd_reg(iproc_i2c, IE_OFFSET); > > > + val &= ~iproc_i2c->slave_int_mask; > > > + iproc_i2c_wr_reg(iproc_i2c, IE_OFFSET, val); > > > + > > > + if (status & BIT(IS_S_RD_EVENT_SHIFT)) > > > + /* Master-write-read request */ > > > + iproc_i2c->slave_rx_only = false; > > > + else > > > + /* Master-write request only */ > > > + iproc_i2c->slave_rx_only = true; > > > + > > > + /* schedule tasklet to read data later */ > > > + tasklet_schedule(&iproc_i2c->slave_rx_tasklet); > > > + > > > + /* clear only IS_S_RX_EVENT_SHIFT interrupt */ > > > + iproc_i2c_wr_reg(iproc_i2c, IS_OFFSET, > > > + BIT(IS_S_RX_EVENT_SHIFT)); > > > > > > > Both tasklet and isr are writing to status (IS_OFFSET) reg. > > > > > > Yes this is required. > > > > For ex, If IS_S_RD_EVENT_SHIFT interrupt, this should be cleared once > > the driver completes reading all data from rx fifo. > > After this the driver can start sending data to master. > > > > If both tasklet and isr are accessing the IS_OFFSET register, don't you > need lock protection against race condition? That is, ISR can interrupt > tasklet. All interrupts are disbaled when the tasklet is running. Interrupts are re-enabled at the end of the tasklet. So no race condition between tasklet and isr. Best regards, Rayagonda > > > > > > > The tasklet seems to be batching up rx fifo reads because of > > time-sensitive > > Master-write-read transaction? Linux I2C framework is byte interface > > anyway. > > Can the need to batch reads be avoided by setting slave rx threshold for > > interrupt (S_FIFO_RX_THLD) to 1-byte? > > > > > > To process more data with a single interrupt we are batching up rx fifo > > reads. > > This will reduce the number of interrupts. > > > > Also to avoid tasklet running more time (20us) we have a threshold of 10 > > bytes for batching read. > > This is a better/optimised approach than reading single byte data per > > interrupt. > > > > > > Also, wouldn't tasklets be susceptible to other interrupts? If fifo > > reads > > have to be batched up, can it be changed to threaded irq? > > > > > > tasklets have higher priority than threaded irq, since i2c is time > > sensitive so using a tasklet is preferred over threaded irq. > >
diff --git a/drivers/i2c/busses/i2c-bcm-iproc.c b/drivers/i2c/busses/i2c-bcm-iproc.c index 7a235f9f5884..22e04055b447 100644 --- a/drivers/i2c/busses/i2c-bcm-iproc.c +++ b/drivers/i2c/busses/i2c-bcm-iproc.c @@ -160,6 +160,11 @@ #define IE_S_ALL_INTERRUPT_SHIFT 21 #define IE_S_ALL_INTERRUPT_MASK 0x3f +/* + * It takes ~18us to reading 10bytes of data, hence to keep tasklet + * running for less time, max slave read per tasklet is set to 10 bytes. + */ +#define MAX_SLAVE_RX_PER_INT 10 enum i2c_slave_read_status { I2C_SLAVE_RX_FIFO_EMPTY = 0, @@ -206,8 +211,18 @@ struct bcm_iproc_i2c_dev { /* bytes that have been read */ unsigned int rx_bytes; unsigned int thld_bytes; + + bool slave_rx_only; + bool rx_start_rcvd; + bool slave_read_complete; + u32 tx_underrun; + u32 slave_int_mask; + struct tasklet_struct slave_rx_tasklet; }; +/* tasklet to process slave rx data */ +static void slave_rx_tasklet_fn(unsigned long); + /* * Can be expanded in the future if more interrupt status bits are utilized */ @@ -261,6 +276,7 @@ static void bcm_iproc_i2c_slave_init( { u32 val; + iproc_i2c->tx_underrun = 0; if (need_reset) { /* put controller in reset */ val = iproc_i2c_rd_reg(iproc_i2c, CFG_OFFSET); @@ -297,8 +313,11 @@ static void bcm_iproc_i2c_slave_init( /* Enable interrupt register to indicate a valid byte in receive fifo */ val = BIT(IE_S_RX_EVENT_SHIFT); + /* Enable interrupt register to indicate a Master read transaction */ + val |= BIT(IE_S_RD_EVENT_SHIFT); /* Enable interrupt register for the Slave BUSY command */ val |= BIT(IE_S_START_BUSY_SHIFT); + iproc_i2c->slave_int_mask = val; iproc_i2c_wr_reg(iproc_i2c, IE_OFFSET, val); } @@ -324,76 +343,176 @@ static void bcm_iproc_i2c_check_slave_status( } } -static bool bcm_iproc_i2c_slave_isr(struct bcm_iproc_i2c_dev *iproc_i2c, - u32 status) +static void bcm_iproc_i2c_slave_read(struct bcm_iproc_i2c_dev *iproc_i2c) { + u8 rx_data, rx_status; + u32 rx_bytes = 0; u32 val; - u8 value, rx_status; - /* Slave RX byte receive */ - if (status & BIT(IS_S_RX_EVENT_SHIFT)) { + while (rx_bytes < MAX_SLAVE_RX_PER_INT) { val = iproc_i2c_rd_reg(iproc_i2c, S_RX_OFFSET); rx_status = (val >> S_RX_STATUS_SHIFT) & S_RX_STATUS_MASK; - if (rx_status == I2C_SLAVE_RX_START) { - /* Start of SMBUS for Master write */ - i2c_slave_event(iproc_i2c->slave, - I2C_SLAVE_WRITE_REQUESTED, &value); + rx_data = ((val >> S_RX_DATA_SHIFT) & S_RX_DATA_MASK); - val = iproc_i2c_rd_reg(iproc_i2c, S_RX_OFFSET); - value = (u8)((val >> S_RX_DATA_SHIFT) & S_RX_DATA_MASK); + if (rx_status == I2C_SLAVE_RX_START) { + /* Start of SMBUS Master write */ i2c_slave_event(iproc_i2c->slave, - I2C_SLAVE_WRITE_RECEIVED, &value); - } else if (status & BIT(IS_S_RD_EVENT_SHIFT)) { - /* Start of SMBUS for Master Read */ + I2C_SLAVE_WRITE_REQUESTED, &rx_data); + iproc_i2c->rx_start_rcvd = true; + iproc_i2c->slave_read_complete = false; + } else if (rx_status == I2C_SLAVE_RX_DATA && + iproc_i2c->rx_start_rcvd) { + /* Middle of SMBUS Master write */ i2c_slave_event(iproc_i2c->slave, - I2C_SLAVE_READ_REQUESTED, &value); - iproc_i2c_wr_reg(iproc_i2c, S_TX_OFFSET, value); + I2C_SLAVE_WRITE_RECEIVED, &rx_data); + } else if (rx_status == I2C_SLAVE_RX_END && + iproc_i2c->rx_start_rcvd) { + /* End of SMBUS Master write */ + if (iproc_i2c->slave_rx_only) + i2c_slave_event(iproc_i2c->slave, + I2C_SLAVE_WRITE_RECEIVED, + &rx_data); + + i2c_slave_event(iproc_i2c->slave, I2C_SLAVE_STOP, + &rx_data); + } else if (rx_status == I2C_SLAVE_RX_FIFO_EMPTY) { + iproc_i2c->rx_start_rcvd = false; + iproc_i2c->slave_read_complete = true; + break; + } - val = BIT(S_CMD_START_BUSY_SHIFT); - iproc_i2c_wr_reg(iproc_i2c, S_CMD_OFFSET, val); + rx_bytes++; + } +} - /* - * Enable interrupt for TX FIFO becomes empty and - * less than PKT_LENGTH bytes were output on the SMBUS - */ - val = iproc_i2c_rd_reg(iproc_i2c, IE_OFFSET); - val |= BIT(IE_S_TX_UNDERRUN_SHIFT); - iproc_i2c_wr_reg(iproc_i2c, IE_OFFSET, val); - } else { - /* Master write other than start */ - value = (u8)((val >> S_RX_DATA_SHIFT) & S_RX_DATA_MASK); +static void slave_rx_tasklet_fn(unsigned long data) +{ + struct bcm_iproc_i2c_dev *iproc_i2c = (struct bcm_iproc_i2c_dev *)data; + u32 int_clr; + + bcm_iproc_i2c_slave_read(iproc_i2c); + + /* clear pending IS_S_RX_EVENT_SHIFT interrupt */ + int_clr = BIT(IS_S_RX_EVENT_SHIFT); + + if (!iproc_i2c->slave_rx_only && iproc_i2c->slave_read_complete) { + /* + * In case of single byte master-read request, + * IS_S_TX_UNDERRUN_SHIFT event is generated before + * IS_S_START_BUSY_SHIFT event. Hence start slave data send + * from first IS_S_TX_UNDERRUN_SHIFT event. + * + * This means don't send any data from slave when + * IS_S_RD_EVENT_SHIFT event is generated else it will increment + * eeprom or other backend slave driver read pointer twice. + */ + iproc_i2c->tx_underrun = 0; + iproc_i2c->slave_int_mask |= BIT(IE_S_TX_UNDERRUN_SHIFT); + + /* clear IS_S_RD_EVENT_SHIFT interrupt */ + int_clr |= BIT(IS_S_RD_EVENT_SHIFT); + } + + /* clear slave interrupt */ + iproc_i2c_wr_reg(iproc_i2c, IS_OFFSET, int_clr); + /* enable slave interrupts */ + iproc_i2c_wr_reg(iproc_i2c, IE_OFFSET, iproc_i2c->slave_int_mask); +} + +static bool bcm_iproc_i2c_slave_isr(struct bcm_iproc_i2c_dev *iproc_i2c, + u32 status) +{ + u32 val; + u8 value; + + /* + * Slave events in case of master-write, master-write-read and, + * master-read + * + * Master-write : only IS_S_RX_EVENT_SHIFT event + * Master-write-read: both IS_S_RX_EVENT_SHIFT and IS_S_RD_EVENT_SHIFT + * events + * Master-read : both IS_S_RX_EVENT_SHIFT and IS_S_RD_EVENT_SHIFT + * events or only IS_S_RD_EVENT_SHIFT + */ + if (status & BIT(IS_S_RX_EVENT_SHIFT) || + status & BIT(IS_S_RD_EVENT_SHIFT)) { + /* disable slave interrupts */ + val = iproc_i2c_rd_reg(iproc_i2c, IE_OFFSET); + val &= ~iproc_i2c->slave_int_mask; + iproc_i2c_wr_reg(iproc_i2c, IE_OFFSET, val); + + if (status & BIT(IS_S_RD_EVENT_SHIFT)) + /* Master-write-read request */ + iproc_i2c->slave_rx_only = false; + else + /* Master-write request only */ + iproc_i2c->slave_rx_only = true; + + /* schedule tasklet to read data later */ + tasklet_schedule(&iproc_i2c->slave_rx_tasklet); + + /* clear only IS_S_RX_EVENT_SHIFT interrupt */ + iproc_i2c_wr_reg(iproc_i2c, IS_OFFSET, + BIT(IS_S_RX_EVENT_SHIFT)); + } + + if (status & BIT(IS_S_TX_UNDERRUN_SHIFT)) { + iproc_i2c->tx_underrun++; + if (iproc_i2c->tx_underrun == 1) + /* Start of SMBUS for Master Read */ i2c_slave_event(iproc_i2c->slave, - I2C_SLAVE_WRITE_RECEIVED, &value); - if (rx_status == I2C_SLAVE_RX_END) - i2c_slave_event(iproc_i2c->slave, - I2C_SLAVE_STOP, &value); - } - } else if (status & BIT(IS_S_TX_UNDERRUN_SHIFT)) { - /* Master read other than start */ - i2c_slave_event(iproc_i2c->slave, - I2C_SLAVE_READ_PROCESSED, &value); + I2C_SLAVE_READ_REQUESTED, + &value); + else + /* Master read other than start */ + i2c_slave_event(iproc_i2c->slave, + I2C_SLAVE_READ_PROCESSED, + &value); iproc_i2c_wr_reg(iproc_i2c, S_TX_OFFSET, value); + /* start transfer */ val = BIT(S_CMD_START_BUSY_SHIFT); iproc_i2c_wr_reg(iproc_i2c, S_CMD_OFFSET, val); + + /* clear interrupt */ + iproc_i2c_wr_reg(iproc_i2c, IS_OFFSET, + BIT(IS_S_TX_UNDERRUN_SHIFT)); } - /* Stop */ + /* Stop received from master in case of master read transaction */ if (status & BIT(IS_S_START_BUSY_SHIFT)) { - i2c_slave_event(iproc_i2c->slave, I2C_SLAVE_STOP, &value); /* * Disable interrupt for TX FIFO becomes empty and * less than PKT_LENGTH bytes were output on the SMBUS */ - val = iproc_i2c_rd_reg(iproc_i2c, IE_OFFSET); - val &= ~BIT(IE_S_TX_UNDERRUN_SHIFT); - iproc_i2c_wr_reg(iproc_i2c, IE_OFFSET, val); + iproc_i2c->slave_int_mask &= ~BIT(IE_S_TX_UNDERRUN_SHIFT); + iproc_i2c_wr_reg(iproc_i2c, IE_OFFSET, + iproc_i2c->slave_int_mask); + + /* End of SMBUS for Master Read */ + val = BIT(S_TX_WR_STATUS_SHIFT); + iproc_i2c_wr_reg(iproc_i2c, S_TX_OFFSET, val); + + val = BIT(S_CMD_START_BUSY_SHIFT); + iproc_i2c_wr_reg(iproc_i2c, S_CMD_OFFSET, val); + + /* flush TX FIFOs */ + val = iproc_i2c_rd_reg(iproc_i2c, S_FIFO_CTRL_OFFSET); + val |= (BIT(S_FIFO_TX_FLUSH_SHIFT)); + iproc_i2c_wr_reg(iproc_i2c, S_FIFO_CTRL_OFFSET, val); + + i2c_slave_event(iproc_i2c->slave, I2C_SLAVE_STOP, &value); + + /* clear interrupt */ + iproc_i2c_wr_reg(iproc_i2c, IS_OFFSET, + BIT(IS_S_START_BUSY_SHIFT)); } - /* clear interrupt status */ - iproc_i2c_wr_reg(iproc_i2c, IS_OFFSET, status); + /* check slave transmit status only if slave is transmitting */ + if (!iproc_i2c->slave_rx_only) + bcm_iproc_i2c_check_slave_status(iproc_i2c); - bcm_iproc_i2c_check_slave_status(iproc_i2c); return true; } @@ -1074,6 +1193,10 @@ static int bcm_iproc_i2c_reg_slave(struct i2c_client *slave) return -EAFNOSUPPORT; iproc_i2c->slave = slave; + + tasklet_init(&iproc_i2c->slave_rx_tasklet, slave_rx_tasklet_fn, + (unsigned long)iproc_i2c); + bcm_iproc_i2c_slave_init(iproc_i2c, false); return 0; } @@ -1094,6 +1217,8 @@ static int bcm_iproc_i2c_unreg_slave(struct i2c_client *slave) IE_S_ALL_INTERRUPT_SHIFT); iproc_i2c_wr_reg(iproc_i2c, IE_OFFSET, tmp); + tasklet_kill(&iproc_i2c->slave_rx_tasklet); + /* Erase the slave address programmed */ tmp = iproc_i2c_rd_reg(iproc_i2c, S_CFG_SMBUS_ADDR_OFFSET); tmp &= ~BIT(S_CFG_EN_NIC_SMB_ADDR3_SHIFT);
Handle single or multi byte master read request with or without repeated start. Fixes: c245d94ed106 ("i2c: iproc: Add multi byte read-write support for slave mode") Signed-off-by: Rayagonda Kokatanur <rayagonda.kokatanur@broadcom.com> --- drivers/i2c/busses/i2c-bcm-iproc.c | 215 +++++++++++++++++++++++------ 1 file changed, 170 insertions(+), 45 deletions(-)