From: Fugang Duan b38611@freescale.com
From i2c spec, if device pull down the SDA line that causes
i2c bus dead, host can send out 9 clock to let device release SDA.
But for some special device like pfuze100, it pull down SDA line and the solution cannot take effort.
The patch just add NACK and STOP signal after 8 dummy clock, and pmic can release SDA line after the recovery. Test case catch 375 times of i2c hang, and all are recovered.
Signed-off-by: Peng Fan Peng.Fan@freescale.com Signed-off-by: Fugang Duan B38611@freescale.com --- arch/arm/imx-common/i2c-mxv7.c | 27 +++++++++++++++++++++++++-- 1 file changed, 25 insertions(+), 2 deletions(-)
diff --git a/arch/arm/imx-common/i2c-mxv7.c b/arch/arm/imx-common/i2c-mxv7.c index 1a632e7..b1d4ec4 100644 --- a/arch/arm/imx-common/i2c-mxv7.c +++ b/arch/arm/imx-common/i2c-mxv7.c @@ -33,13 +33,36 @@ static int force_idle_bus(void *priv)
printf("%s: sda=%d scl=%d sda.gp=0x%x scl.gp=0x%x\n", __func__, sda, scl, p->sda.gp, p->scl.gp); + gpio_direction_output(p->scl.gp, 1); + udelay(1000); /* Send high and low on the SCL line */ for (i = 0; i < 9; i++) { - gpio_direction_output(p->scl.gp, 0); + gpio_direction_output(p->scl.gp, 1); udelay(50); - gpio_direction_input(p->scl.gp); + gpio_direction_output(p->scl.gp, 0); udelay(50); } + + /* Simulate the NACK */ + gpio_direction_output(p->sda.gp, 1); + udelay(50); + gpio_direction_output(p->scl.gp, 1); + udelay(50); + gpio_direction_output(p->scl.gp, 0); + udelay(50); + + /* Simulate the STOP signal */ + gpio_direction_output(p->sda.gp, 0); + udelay(50); + gpio_direction_output(p->scl.gp, 1); + udelay(50); + gpio_direction_output(p->sda.gp, 1); + udelay(50); + + /* Get the bus status */ + gpio_direction_input(p->sda.gp); + gpio_direction_input(p->scl.gp); + start_time = get_timer(0); for (;;) { sda = gpio_get_value(p->sda.gp);