From 81687212ee0b4fcb11f7d6700275b062c8f8d2b4 Mon Sep 17 00:00:00 2001 From: Stefano Babic Date: Thu, 20 Jan 2011 07:51:31 +0000 Subject: [PATCH] I2C: mxc_i2c: address failure with mx35 processor There is sporadic failures when more as one I2C slave is on the bus and the processor tries to communicate with more as one slave. The problem was seen on a mx35pdk (two I2C slaves, PMIC controller and CAN/RTC chip). The current driver uses the IIF bit in the status register to check if the bus is busy or not. According to the manual, this is not correct, because the IIB bit should be checked. Not only, to check if a transfer is finished must be checked the ICF bit, and this is not tested at all. This patch comes from analyse with a corresponding driver provided by Freescale as part of the LTIB tool. Comparing the two drivers, it appears that the current u-boot driver checks the wrong bits, and depending on race condition, the transfer can be successful or not. The patch gets rid also of own debug function (DPRINTF), replaced with the general debug(). Tested on Freescale mx35pdk. Signed-off-by: Stefano Babic CC: Heiko Schocher Acked-by: Heiko Schocher --- drivers/i2c/mxc_i2c.c | 88 +++++++++++++++++++++++++++++++++---------- 1 file changed, 69 insertions(+), 19 deletions(-) diff --git a/drivers/i2c/mxc_i2c.c b/drivers/i2c/mxc_i2c.c index fd6db1855..c5ec486a7 100644 --- a/drivers/i2c/mxc_i2c.c +++ b/drivers/i2c/mxc_i2c.c @@ -72,11 +72,8 @@ #error "define CONFIG_SYS_I2C_MX_PORTx to use the mx I2C driver" #endif -#ifdef DEBUG -#define DPRINTF(args...) printf(args) -#else -#define DPRINTF(args...) -#endif +#define I2C_MAX_TIMEOUT 10000 +#define I2C_MAX_RETRIES 3 static u16 div[] = { 30, 32, 36, 42, 48, 52, 60, 72, 80, 88, 104, 128, 144, 160, 192, 240, 288, 320, 384, 480, 576, 640, 768, 960, @@ -116,31 +113,61 @@ void i2c_init(int speed, int unused) i2c_reset(); } +static int wait_idle(void) +{ + int timeout = I2C_MAX_TIMEOUT; + + while ((readw(I2C_BASE + I2SR) & I2SR_IBB) && --timeout) { + writew(0, I2C_BASE + I2SR); + udelay(1); + } + return timeout ? timeout : (!(readw(I2C_BASE + I2SR) & I2SR_IBB)); +} + static int wait_busy(void) { - int timeout = 10000; + int timeout = I2C_MAX_TIMEOUT; - while (!(readw(I2C_BASE + I2SR) & I2SR_IIF) && --timeout) + while (!(readw(I2C_BASE + I2SR) & I2SR_IBB) && --timeout) udelay(1); writew(0, I2C_BASE + I2SR); /* clear interrupt */ return timeout; } +static int wait_complete(void) +{ + int timeout = I2C_MAX_TIMEOUT; + + while ((!(readw(I2C_BASE + I2SR) & I2SR_ICF)) && (--timeout)) { + writew(0, I2C_BASE + I2SR); + udelay(1); + } + udelay(200); + + writew(0, I2C_BASE + I2SR); /* clear interrupt */ + + return timeout; +} + + static int tx_byte(u8 byte) { writew(byte, I2C_BASE + I2DR); - if (!wait_busy() || readw(I2C_BASE + I2SR) & I2SR_RX_NO_AK) + if (!wait_complete() || readw(I2C_BASE + I2SR) & I2SR_RX_NO_AK) return -1; return 0; } -static int rx_byte(void) +static int rx_byte(int last) { - if (!wait_busy()) + if (!wait_complete()) return -1; + if (last) + writew(I2CR_IEN, I2C_BASE + I2CR); + return readw(I2C_BASE + I2DR); } @@ -160,21 +187,45 @@ int i2c_probe(uchar chip) static int i2c_addr(uchar chip, uint addr, int alen) { - writew(0, I2C_BASE + I2SR); - writew(I2CR_IEN | I2CR_MSTA | I2CR_MTX, I2C_BASE + I2CR); - - if (tx_byte(chip << 1)) + int i, retry = 0; + for (retry = 0; retry < 3; retry++) { + if (wait_idle()) + break; + i2c_reset(); + for (i = 0; i < I2C_MAX_TIMEOUT; i++) + udelay(1); + } + if (retry >= I2C_MAX_RETRIES) { + debug("%s:bus is busy(%x)\n", + __func__, readw(I2C_BASE + I2SR)); return -1; + } + writew(I2CR_IEN | I2CR_MSTA | I2CR_MTX, I2C_BASE + I2CR); + if (!wait_busy()) { + debug("%s:trigger start fail(%x)\n", + __func__, readw(I2C_BASE + I2SR)); + return -1; + } + + if (tx_byte(chip << 1) || (readw(I2C_BASE + I2SR) & I2SR_RX_NO_AK)) { + debug("%s:chip address cycle fail(%x)\n", + __func__, readw(I2C_BASE + I2SR)); + return -1; + } while (alen--) - if (tx_byte((addr >> (alen * 8)) & 0xff)) + if (tx_byte((addr >> (alen * 8)) & 0xff) || + (readw(I2C_BASE + I2SR) & I2SR_RX_NO_AK)) { + debug("%s:device address cycle fail(%x)\n", + __func__, readw(I2C_BASE + I2SR)); return -1; + } return 0; } int i2c_read(uchar chip, uint addr, int alen, uchar *buf, int len) { - int timeout = 10000; + int timeout = I2C_MAX_TIMEOUT; int ret; debug("%s chip: 0x%02x addr: 0x%04x alen: %d len: %d\n", @@ -197,7 +248,8 @@ int i2c_read(uchar chip, uint addr, int alen, uchar *buf, int len) ret = readw(I2C_BASE + I2DR); while (len--) { - if ((ret = rx_byte()) < 0) + ret = rx_byte(len == 0); + if (ret < 0) return -1; *buf++ = ret; if (len <= 1) @@ -206,8 +258,6 @@ int i2c_read(uchar chip, uint addr, int alen, uchar *buf, int len) I2C_BASE + I2CR); } - wait_busy(); - writew(I2CR_IEN, I2C_BASE + I2CR); while (readw(I2C_BASE + I2SR) & I2SR_IBB && --timeout)