From: Peter Swain <[email protected]> Consider more status codes and improve error handling. Distinguish handling for first and last part of a message.
TODO: Convert to use the i2c recovery framework. Signed-off-by: Peter Swain <[email protected]> Signed-off-by: Jan Glauber <[email protected]> --- drivers/i2c/busses/i2c-octeon.c | 244 +++++++++++++++++++++++++++++----------- 1 file changed, 178 insertions(+), 66 deletions(-) diff --git a/drivers/i2c/busses/i2c-octeon.c b/drivers/i2c/busses/i2c-octeon.c index f647667..a037245 100644 --- a/drivers/i2c/busses/i2c-octeon.c +++ b/drivers/i2c/busses/i2c-octeon.c @@ -56,12 +56,34 @@ #define TWSI_CTL_AAK 0x04 /* Assert ACK */ /* Some status values */ +#define STAT_ERROR 0x00 #define STAT_START 0x08 #define STAT_RSTART 0x10 #define STAT_TXADDR_ACK 0x18 +#define STAT_TXADDR_NAK 0x20 #define STAT_TXDATA_ACK 0x28 +#define STAT_TXDATA_NAK 0x30 +#define STAT_LOST_ARB_38 0x38 #define STAT_RXADDR_ACK 0x40 +#define STAT_RXADDR_NAK 0x48 #define STAT_RXDATA_ACK 0x50 +#define STAT_RXDATA_NAK 0x58 +#define STAT_SLAVE_60 0x60 +#define STAT_LOST_ARB_68 0x68 +#define STAT_SLAVE_70 0x70 +#define STAT_LOST_ARB_78 0x78 +#define STAT_SLAVE_80 0x80 +#define STAT_SLAVE_88 0x88 +#define STAT_GENDATA_ACK 0x90 +#define STAT_GENDATA_NAK 0x98 +#define STAT_SLAVE_A0 0xA0 +#define STAT_SLAVE_A8 0xA8 +#define STAT_LOST_ARB_B0 0xB0 +#define STAT_SLAVE_LOST 0xB8 +#define STAT_SLAVE_NAK 0xC0 +#define STAT_SLAVE_ACK 0xC8 +#define STAT_AD2W_ACK 0xD0 +#define STAT_AD2W_NAK 0xD8 #define STAT_IDLE 0xF8 /* TWSI_INT values */ @@ -79,6 +101,8 @@ struct octeon_i2c { struct device *dev; }; +static int reset_how; + /** * octeon_i2c_write_sw - write an I2C core register * @i2c: The struct octeon_i2c @@ -186,7 +210,6 @@ static irqreturn_t octeon_i2c_isr(int irq, void *dev_id) return IRQ_HANDLED; } - static int octeon_i2c_test_iflg(struct octeon_i2c *i2c) { return (octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_CTL) & TWSI_CTL_IFLG) != 0; @@ -214,6 +237,66 @@ static int octeon_i2c_wait(struct octeon_i2c *i2c) return 0; } +static int octeon_i2c_lost_arb(u8 code, int final_read) +{ + switch (code) { + /* Arbitration lost */ + case STAT_LOST_ARB_38: + case STAT_LOST_ARB_68: + case STAT_LOST_ARB_78: + case STAT_LOST_ARB_B0: + return -EAGAIN; + + /* Being addressed as slave, should back off & listen */ + case STAT_SLAVE_60: + case STAT_SLAVE_70: + case STAT_GENDATA_ACK: + case STAT_GENDATA_NAK: + return -EIO; + + /* Core busy as slave */ + case STAT_SLAVE_80: + case STAT_SLAVE_88: + case STAT_SLAVE_A0: + case STAT_SLAVE_A8: + case STAT_SLAVE_LOST: + case STAT_SLAVE_NAK: + case STAT_SLAVE_ACK: + return -EIO; + + /* ACK allowed on pre-terminal bytes only */ + case STAT_RXDATA_ACK: + if (!final_read) + return 0; + return -EAGAIN; + + /* NAK allowed on terminal byte only */ + case STAT_RXDATA_NAK: + if (final_read) + return 0; + return -EAGAIN; + case STAT_TXDATA_NAK: + case STAT_TXADDR_NAK: + case STAT_RXADDR_NAK: + case STAT_AD2W_NAK: + return -EAGAIN; + } + return 0; +} + +static int check_arb(struct octeon_i2c *i2c, int final_read) +{ + return octeon_i2c_lost_arb(octeon_i2c_read_sw(i2c, + SW_TWSI_EOP_TWSI_STAT), final_read); +} + +/* send STOP to the bus */ +static void octeon_i2c_stop(struct octeon_i2c *i2c) +{ + octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL, + TWSI_CTL_ENAB | TWSI_CTL_STP); +} + /* calculate and set clock divisors */ static void octeon_i2c_set_clock(struct octeon_i2c *i2c) { @@ -277,71 +360,103 @@ static int octeon_i2c_init_lowlevel(struct octeon_i2c *i2c) return -EIO; } +/* + * TWSI state seems stuck. Not sure if it's TWSI-engine state or something + * else on bus. The initial _stop() is always harmless, it just resets state + * machine, does not _transmit_ STOP unless engine was active. + */ +static int start_unstick(struct octeon_i2c *i2c) +{ + octeon_i2c_stop(i2c); + + /* + * Response is escalated over successive calls, + * as EAGAIN provokes retries from i2c/core. + */ + switch (reset_how++ % 4) { + case 0: + /* just the stop above */ + break; + case 1: + /* + * Controller refused to send start flag. May be a + * client is holding SDA low? Let's try to free it. + */ + octeon_i2c_unblock(i2c); + break; + case 2: + /* re-init our TWSI hardware */ + octeon_i2c_init_lowlevel(i2c); + break; + default: + /* retry in caller */ + reset_how = 0; + return -EAGAIN; + } + return 0; +} + /** * octeon_i2c_start - send START to the bus * @i2c: The struct octeon_i2c + * @first: first msg in combined operation? * * Returns 0 on success, otherwise a negative errno. */ -static int octeon_i2c_start(struct octeon_i2c *i2c) +static int octeon_i2c_start(struct octeon_i2c *i2c, int first) { int result; u8 data; - octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL, - TWSI_CTL_ENAB | TWSI_CTL_STA); + while (1) { + octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL, + TWSI_CTL_ENAB | TWSI_CTL_STA); - result = octeon_i2c_wait(i2c); - if (result) { - if (octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT) == STAT_IDLE) { - /* - * Controller refused to send start flag May - * be a client is holding SDA low - let's try - * to free it. - */ - octeon_i2c_unblock(i2c); - octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL, - TWSI_CTL_ENAB | TWSI_CTL_STA); - result = octeon_i2c_wait(i2c); + result = octeon_i2c_wait(i2c); + data = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT); + + switch (data) { + case STAT_START: + case STAT_RSTART: + if (!first) + return -EAGAIN; + reset_how = 0; + return 0; + case STAT_RXADDR_ACK: + if (first) + return -EAGAIN; + return start_unstick(i2c); + /* + * case STAT_IDLE: + * case STAT_ERROR: + */ + default: + if (!first) + return -EAGAIN; + start_unstick(i2c); } - if (result) - return result; } - - data = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT); - if ((data != STAT_START) && (data != STAT_RSTART)) { - dev_err(i2c->dev, "%s: bad status (0x%x)\n", __func__, data); - return -EIO; - } - return 0; } -/* send STOP to the bus */ -static void octeon_i2c_stop(struct octeon_i2c *i2c) -{ - octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL, - TWSI_CTL_ENAB | TWSI_CTL_STP); -} - /** * octeon_i2c_write - send data to the bus via low-level controller * @i2c: The struct octeon_i2c * @target: Target address * @data: Pointer to the data to be sent * @length: Length of the data + * @last: is last msg in combined operation? * * The address is sent over the bus, then the data. * * Returns 0 on success, otherwise a negative errno. */ static int octeon_i2c_write(struct octeon_i2c *i2c, int target, - const u8 *data, int length) + const u8 *data, int length, int first, int last) { int i, result; - u8 tmp; - result = octeon_i2c_start(i2c); + result = octeon_i2c_start(i2c, first); if (result) return result; @@ -353,14 +468,9 @@ static int octeon_i2c_write(struct octeon_i2c *i2c, int target, return result; for (i = 0; i < length; i++) { - tmp = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT); - - if ((tmp != STAT_TXADDR_ACK) && (tmp != STAT_TXDATA_ACK)) { - dev_err(i2c->dev, - "%s: bad status before write (0x%x)\n", - __func__, tmp); - return -EIO; - } + result = check_arb(i2c, false); + if (result) + return result; octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_DATA, data[i]); octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL, TWSI_CTL_ENAB); @@ -368,6 +478,9 @@ static int octeon_i2c_write(struct octeon_i2c *i2c, int target, result = octeon_i2c_wait(i2c); if (result) return result; + result = check_arb(i2c, false); + if (result) + return result; } return 0; @@ -379,54 +492,51 @@ static int octeon_i2c_write(struct octeon_i2c *i2c, int target, * @target: Target address * @data: Pointer to the location to store the data * @rlength: Length of the data + * @phase: which phase of a combined operation. * @recv_len: flag for length byte * * The address is sent over the bus, then the data is read. * * Returns 0 on success, otherwise a negative errno. */ -static int octeon_i2c_read(struct octeon_i2c *i2c, int target, - u8 *data, u16 *rlength, bool recv_len) +static int octeon_i2c_read(struct octeon_i2c *i2c, int target, u8 *data, + u16 *rlength, bool first, bool last, bool recv_len) { + u8 ctl = TWSI_CTL_ENAB | TWSI_CTL_AAK; int i, result, length = *rlength; u8 tmp; if (length < 1) return -EINVAL; - result = octeon_i2c_start(i2c); + result = octeon_i2c_start(i2c, first); if (result) return result; octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_DATA, (target << 1) | 1); - octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL, TWSI_CTL_ENAB); - - result = octeon_i2c_wait(i2c); - if (result) - return result; - for (i = 0; i < length; i++) { + for (i = 0; i < length; ) { tmp = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT); + result = octeon_i2c_lost_arb(tmp, !(ctl & TWSI_CTL_AAK)); + if (result) + return result; - if ((tmp != STAT_RXDATA_ACK) && (tmp != STAT_RXADDR_ACK)) { - dev_err(i2c->dev, - "%s: bad status before read (0x%x)\n", - __func__, tmp); - return -EIO; + switch (tmp) { + case STAT_RXDATA_ACK: + case STAT_RXDATA_NAK: + data[i++] = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_DATA); } - if (i + 1 < length) - octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL, - TWSI_CTL_ENAB | TWSI_CTL_AAK); - else - octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL, - TWSI_CTL_ENAB); + /* NAK last recv'd byte, as a no-more-please */ + if (last && i == length - 1) + ctl &= ~TWSI_CTL_AAK; + /* clr iflg to allow next event */ + octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL, ctl); result = octeon_i2c_wait(i2c); if (result) return result; - data[i] = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_DATA); if (recv_len && i == 0) { if (data[i] > I2C_SMBUS_BLOCK_MAX + 1) { dev_err(i2c->dev, @@ -457,6 +567,7 @@ static int octeon_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, for (i = 0; ret == 0 && i < num; i++) { struct i2c_msg *pmsg = &msgs[i]; + bool last = (i == (num - 1)); dev_dbg(i2c->dev, "Doing %s %d byte(s) to/from 0x%02x - %d of %d messages\n", @@ -464,10 +575,11 @@ static int octeon_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, pmsg->len, pmsg->addr, i + 1, num); if (pmsg->flags & I2C_M_RD) ret = octeon_i2c_read(i2c, pmsg->addr, pmsg->buf, - &pmsg->len, pmsg->flags & I2C_M_RECV_LEN); + &pmsg->len, !i, last, + pmsg->flags & I2C_M_RECV_LEN); else ret = octeon_i2c_write(i2c, pmsg->addr, pmsg->buf, - pmsg->len); + pmsg->len, !i, last); } octeon_i2c_stop(i2c); -- 1.9.1
