diff options
| -rw-r--r-- | drivers/i2c/busses/i2c-imx.c | 41 |
1 files changed, 30 insertions, 11 deletions
diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c index 886217f1ba6..5f4bc700825 100644 --- a/drivers/i2c/busses/i2c-imx.c +++ b/drivers/i2c/busses/i2c-imx.c @@ -458,7 +458,7 @@ static int i2c_imx_write(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs) return 0; } -static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs) +static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs, bool is_lastmsg) { int i, result; unsigned int temp; @@ -515,15 +515,30 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs) msgs->len += len; } 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 = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR); - temp &= ~(I2CR_MSTA | I2CR_MTX); - imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR); - i2c_imx_bus_busy(i2c_imx, 0); - i2c_imx->stopped = 1; + if (is_lastmsg) { + /* + * 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 = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR); + temp &= ~(I2CR_MSTA | I2CR_MTX); + imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR); + i2c_imx_bus_busy(i2c_imx, 0); + i2c_imx->stopped = 1; + } else { + /* + * For i2c master receiver repeat restart operation like: + * read -> repeat MSTA -> read/write + * The controller must set MTX before read the last byte in + * the first read operation, otherwise the first read cost + * one extra clock cycle. + */ + temp = readb(i2c_imx->base + IMX_I2C_I2CR); + temp |= I2CR_MTX; + writeb(temp, i2c_imx->base + IMX_I2C_I2CR); + } } else if (i == (msgs->len - 2)) { dev_dbg(&i2c_imx->adapter.dev, "<%s> set TXAK\n", __func__); @@ -547,6 +562,7 @@ static int i2c_imx_xfer(struct i2c_adapter *adapter, { unsigned int i, temp; int result; + bool is_lastmsg = false; struct imx_i2c_struct *i2c_imx = i2c_get_adapdata(adapter); dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__); @@ -558,6 +574,9 @@ static int i2c_imx_xfer(struct i2c_adapter *adapter, /* read/write data */ for (i = 0; i < num; i++) { + if (i == num - 1) + is_lastmsg = true; + if (i) { dev_dbg(&i2c_imx->adapter.dev, "<%s> repeated start\n", __func__); @@ -588,7 +607,7 @@ static int i2c_imx_xfer(struct i2c_adapter *adapter, (temp & I2SR_RXAK ? 1 : 0)); #endif if (msgs[i].flags & I2C_M_RD) - result = i2c_imx_read(i2c_imx, &msgs[i]); + result = i2c_imx_read(i2c_imx, &msgs[i], is_lastmsg); else result = i2c_imx_write(i2c_imx, &msgs[i]); if (result) |