From: Rayagonda Kokatanur rayagonda.kokatanur@broadcom.com
[ Upstream commit e21d79778768e4e187b2892d662c6aaa01e1d399 ]
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 Acked-by: Ray Jui ray.jui@broadcom.com Signed-off-by: Wolfram Sang wsa@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/i2c/busses/i2c-bcm-iproc.c | 215 +++++++++++++++++++++++------ 1 file changed, 170 insertions(+), 45 deletions(-)
diff --git a/drivers/i2c/busses/i2c-bcm-iproc.c b/drivers/i2c/busses/i2c-bcm-iproc.c index 68db2068f38b0..35baca2f62c4e 100644 --- a/drivers/i2c/busses/i2c-bcm-iproc.c +++ b/drivers/i2c/busses/i2c-bcm-iproc.c @@ -159,6 +159,11 @@
#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, @@ -205,8 +210,18 @@ 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 */ @@ -260,6 +275,7 @@ 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); @@ -296,8 +312,11 @@ 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); }
@@ -322,76 +341,176 @@ 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); /* * 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); + 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; }
@@ -1072,6 +1191,10 @@ 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; } @@ -1092,6 +1215,8 @@ 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);