From 77e351d9d17cf8e8ad1c70200192ac59285b3096 Mon Sep 17 00:00:00 2001 From: Ben Gardner Date: Wed, 23 Mar 2016 09:40:37 -0500 Subject: intel/fsp_baytrail: Fix I2C abort logic A call to i2c_read() for a non-existent address followed by an i2c_read() to a valid address results in a false abort status for the 2nd call. i2c_read(1, 0x40, 0, buf, sizeof(buf)) => 0x2000000 (I2C_ERR_TIMEOUT) i2c_read(1, 0x74, 0, buf, sizeof(buf)) => 0x4000000 (I2C_ERR_ABORT) Because the abort status register is cleared on read and wait_tx_fifo() reads it twice, the returned status does not contain the abort status. Fixing that changed the 2nd read to reflect the abort status. i2c_read(1, 0x40, 0, buf, sizeof(buf)) => 0x2000000 (I2C_ERR_TIMEOUT) i2c_read(1, 0x74, 0, buf, sizeof(buf)) => 0x4000001 (I2C_ERR_ABORT) Bit 0 indicates that the address was not acknowledged by any slave. That's the abort status from the previous transaction. So I added a read of the abort status before starting a transaction in both i2c_read() and i2c_write(). i2c_read(1, 0x40, 0, buf, sizeof(buf)) => 0x2000000 (I2C_ERR_TIMEOUT) i2c_read(1, 0x74, 0, buf, sizeof(buf)) => 0 (I2C_SUCCESS) Tested on a Bay Trail E3845 SoC. Change-Id: I39e4ff4206587267b6fceef58f4a567bf162fbbe Signed-off-by: Ben Gardner Reviewed-on: https://review.coreboot.org/14160 Tested-by: build bot (Jenkins) Reviewed-by: Martin Roth Reviewed-by: Werner Zeh --- src/soc/intel/fsp_baytrail/i2c.c | 27 +++++++++++++++++++-------- 1 file changed, 19 insertions(+), 8 deletions(-) (limited to 'src/soc') diff --git a/src/soc/intel/fsp_baytrail/i2c.c b/src/soc/intel/fsp_baytrail/i2c.c index 5a0d59dfa6..eb83180dd9 100644 --- a/src/soc/intel/fsp_baytrail/i2c.c +++ b/src/soc/intel/fsp_baytrail/i2c.c @@ -26,12 +26,13 @@ static int wait_tx_fifo(char *base_adr) { int i; + u32 as; - if (read32(base_adr + I2C_ABORT_SOURCE) & 0x1ffff) { + as = read32(base_adr + I2C_ABORT_SOURCE) & 0x1ffff; + if (as) { /* Reading back I2C_CLR_TX_ABRT resets abort lock on TX FIFO */ - i = *((volatile unsigned int *)(base_adr + I2C_CLR_TX_ABRT)); - return I2C_ERR_ABORT | - (*((unsigned int *)(base_adr + I2C_ABORT_SOURCE)) & 0x1ffff); + i = read32(base_adr + I2C_CLR_TX_ABRT); + return I2C_ERR_ABORT | as; } /* Wait here for a free slot in TX-FIFO */ @@ -51,11 +52,13 @@ static int wait_tx_fifo(char *base_adr) static int wait_rx_fifo(char *base_adr) { int i; - if (read32(base_adr + I2C_ABORT_SOURCE) & 0x1ffff) { + u32 as; + + as = read32(base_adr + I2C_ABORT_SOURCE) & 0x1ffff; + if (as) { /* Reading back I2C_CLR_TX_ABRT resets abort lock on TX FIFO */ - i = *((volatile unsigned int *)(base_adr + I2C_CLR_TX_ABRT)); - return I2C_ERR_ABORT | - (*((unsigned int *)(base_adr + I2C_ABORT_SOURCE)) & 0x1ffff); + i = read32(base_adr + I2C_CLR_TX_ABRT); + return I2C_ERR_ABORT | as; } /* Wait here for a received entry in RX-FIFO */ @@ -177,6 +180,10 @@ int i2c_read(unsigned bus, unsigned chip, unsigned addr, stat = wait_for_idle(base_ptr); if (stat != I2C_SUCCESS) return stat; + + /* clear any abort status from a previous transaction */ + read32(base_ptr + I2C_CLR_TX_ABRT); + /* Now we can program the desired slave address and start transfer */ write32(base_ptr + I2C_TARGET_ADR, chip & 0xff); /* Send address inside slave to read from */ @@ -232,6 +239,10 @@ int i2c_write(unsigned bus, unsigned chip, unsigned addr, if (stat) { return stat; } + + /* clear any abort status from a previous transaction */ + read32(base_ptr + I2C_CLR_TX_ABRT); + /* Program slave address to use for this transfer */ write32(base_ptr + I2C_TARGET_ADR, chip & 0xff); -- cgit v1.2.3