diff options
Diffstat (limited to 'drivers/i2c')
| -rw-r--r-- | drivers/i2c/busses/i2c-imx.c | 62 |
1 files changed, 44 insertions, 18 deletions
diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c index 4afba3ec2a6..6055e92f0ac 100644 --- a/drivers/i2c/busses/i2c-imx.c +++ b/drivers/i2c/busses/i2c-imx.c @@ -120,19 +120,25 @@ struct imx_i2c_struct { wait_queue_head_t queue; unsigned long i2csr; unsigned int disable_delay; + int stopped; }; /** Functions for IMX I2C adapter driver *************************************** *******************************************************************************/ -static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx) +static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx, int for_busy) { unsigned long orig_jiffies = jiffies; + unsigned int temp; dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__); - /* wait for bus not busy */ - while (readb(i2c_imx->base + IMX_I2C_I2SR) & I2SR_IBB) { + while (1) { + temp = readb(i2c_imx->base + IMX_I2C_I2SR); + if (for_busy && (temp & I2SR_IBB)) + break; + if (!for_busy && !(temp & I2SR_IBB)) + break; if (signal_pending(current)) { dev_dbg(&i2c_imx->adapter.dev, "<%s> I2C Interrupted\n", __func__); @@ -179,39 +185,55 @@ static int i2c_imx_acked(struct imx_i2c_struct *i2c_imx) return 0; } -static void i2c_imx_start(struct imx_i2c_struct *i2c_imx) +static int i2c_imx_start(struct imx_i2c_struct *i2c_imx) { unsigned int temp = 0; + int result; dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__); /* Enable I2C controller */ + writeb(0, i2c_imx->base + IMX_I2C_I2SR); writeb(I2CR_IEN, i2c_imx->base + IMX_I2C_I2CR); + + /* Wait controller to be stable */ + udelay(50); + /* Start I2C transaction */ temp = readb(i2c_imx->base + IMX_I2C_I2CR); temp |= I2CR_MSTA; writeb(temp, i2c_imx->base + IMX_I2C_I2CR); + result = i2c_imx_bus_busy(i2c_imx, 1); + if (result) + return result; + i2c_imx->stopped = 0; + temp |= I2CR_IIEN | I2CR_MTX | I2CR_TXAK; writeb(temp, i2c_imx->base + IMX_I2C_I2CR); + return result; } static void i2c_imx_stop(struct imx_i2c_struct *i2c_imx) { unsigned int temp = 0; - /* Stop I2C transaction */ - dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__); - temp = readb(i2c_imx->base + IMX_I2C_I2CR); - temp &= ~I2CR_MSTA; - writeb(temp, i2c_imx->base + IMX_I2C_I2CR); - /* setup chip registers to defaults */ - writeb(I2CR_IEN, i2c_imx->base + IMX_I2C_I2CR); - writeb(0, i2c_imx->base + IMX_I2C_I2SR); + if (!i2c_imx->stopped) { + /* Stop I2C transaction */ + dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__); + temp = readb(i2c_imx->base + IMX_I2C_I2CR); + temp &= ~(I2CR_MSTA | I2CR_MTX); + writeb(temp, i2c_imx->base + IMX_I2C_I2CR); + i2c_imx->stopped = 1; + } /* * This delay caused by an i.MXL hardware bug. * If no (or too short) delay, no "STOP" bit will be generated. */ udelay(i2c_imx->disable_delay); + + if (!i2c_imx->stopped) + i2c_imx_bus_busy(i2c_imx, 0); + /* Disable I2C controller */ writeb(0, i2c_imx->base + IMX_I2C_I2CR); } @@ -341,11 +363,15 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs) if (result) return result; if (i == (msgs->len - 1)) { + /* It must generate STOP before read I2DR to prevent + controller from generating another clock cycle */ dev_dbg(&i2c_imx->adapter.dev, "<%s> clear MSTA\n", __func__); temp = readb(i2c_imx->base + IMX_I2C_I2CR); - temp &= ~I2CR_MSTA; + temp &= ~(I2CR_MSTA | I2CR_MTX); writeb(temp, i2c_imx->base + IMX_I2C_I2CR); + i2c_imx_bus_busy(i2c_imx, 0); + i2c_imx->stopped = 1; } else if (i == (msgs->len - 2)) { dev_dbg(&i2c_imx->adapter.dev, "<%s> set TXAK\n", __func__); @@ -370,14 +396,11 @@ static int i2c_imx_xfer(struct i2c_adapter *adapter, dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__); - /* Check if i2c bus is not busy */ - result = i2c_imx_bus_busy(i2c_imx); + /* Start I2C transfer */ + result = i2c_imx_start(i2c_imx); if (result) goto fail0; - /* Start I2C transfer */ - i2c_imx_start(i2c_imx); - /* read/write data */ for (i = 0; i < num; i++) { if (i) { @@ -386,6 +409,9 @@ static int i2c_imx_xfer(struct i2c_adapter *adapter, temp = readb(i2c_imx->base + IMX_I2C_I2CR); temp |= I2CR_RSTA; writeb(temp, i2c_imx->base + IMX_I2C_I2CR); + result = i2c_imx_bus_busy(i2c_imx, 1); + if (result) + goto fail0; } dev_dbg(&i2c_imx->adapter.dev, "<%s> transfer message: %d\n", __func__, i); |