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path: root/drivers/i2c/busses/i2c-mxs.c
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Diffstat (limited to 'drivers/i2c/busses/i2c-mxs.c')
-rw-r--r--drivers/i2c/busses/i2c-mxs.c104
1 files changed, 82 insertions, 22 deletions
diff --git a/drivers/i2c/busses/i2c-mxs.c b/drivers/i2c/busses/i2c-mxs.c
index 120f24646696..c67d89fc6254 100644
--- a/drivers/i2c/busses/i2c-mxs.c
+++ b/drivers/i2c/busses/i2c-mxs.c
@@ -56,6 +56,7 @@
#define MXS_I2C_CTRL1_SET (0x44)
#define MXS_I2C_CTRL1_CLR (0x48)
+#define MXS_I2C_CTRL1_CLR_GOT_A_NAK 0x10000000
#define MXS_I2C_CTRL1_BUS_FREE_IRQ 0x80
#define MXS_I2C_CTRL1_DATA_ENGINE_CMPLT_IRQ 0x40
#define MXS_I2C_CTRL1_NO_SLAVE_ACK_IRQ 0x20
@@ -65,6 +66,10 @@
#define MXS_I2C_CTRL1_SLAVE_STOP_IRQ 0x02
#define MXS_I2C_CTRL1_SLAVE_IRQ 0x01
+#define MXS_I2C_STAT (0x50)
+#define MXS_I2C_STAT_BUS_BUSY 0x00000800
+#define MXS_I2C_STAT_CLK_GEN_BUSY 0x00000400
+
#define MXS_I2C_DATA (0xa0)
#define MXS_I2C_DEBUG0 (0xb0)
@@ -297,12 +302,10 @@ static int mxs_i2c_pio_wait_dmareq(struct mxs_i2c_dev *i2c)
cond_resched();
}
- writel(MXS_I2C_DEBUG0_DMAREQ, i2c->regs + MXS_I2C_DEBUG0_CLR);
-
return 0;
}
-static int mxs_i2c_pio_wait_cplt(struct mxs_i2c_dev *i2c)
+static int mxs_i2c_pio_wait_cplt(struct mxs_i2c_dev *i2c, int last)
{
unsigned long timeout = jiffies + msecs_to_jiffies(1000);
@@ -323,9 +326,50 @@ static int mxs_i2c_pio_wait_cplt(struct mxs_i2c_dev *i2c)
writel(MXS_I2C_CTRL1_DATA_ENGINE_CMPLT_IRQ,
i2c->regs + MXS_I2C_CTRL1_CLR);
+ /*
+ * When ending a transfer with a stop, we have to wait for the bus to
+ * go idle before we report the transfer as completed. Otherwise the
+ * start of the next transfer may race with the end of the current one.
+ */
+ while (last && (readl(i2c->regs + MXS_I2C_STAT) &
+ (MXS_I2C_STAT_BUS_BUSY | MXS_I2C_STAT_CLK_GEN_BUSY))) {
+ if (time_after(jiffies, timeout))
+ return -ETIMEDOUT;
+ cond_resched();
+ }
+
return 0;
}
+static int mxs_i2c_pio_check_error_state(struct mxs_i2c_dev *i2c)
+{
+ u32 state;
+
+ state = readl(i2c->regs + MXS_I2C_CTRL1_CLR) & MXS_I2C_IRQ_MASK;
+
+ if (state & MXS_I2C_CTRL1_NO_SLAVE_ACK_IRQ)
+ i2c->cmd_err = -ENXIO;
+ else if (state & (MXS_I2C_CTRL1_EARLY_TERM_IRQ |
+ MXS_I2C_CTRL1_MASTER_LOSS_IRQ |
+ MXS_I2C_CTRL1_SLAVE_STOP_IRQ |
+ MXS_I2C_CTRL1_SLAVE_IRQ))
+ i2c->cmd_err = -EIO;
+
+ return i2c->cmd_err;
+}
+
+static void mxs_i2c_pio_trigger_cmd(struct mxs_i2c_dev *i2c, u32 cmd)
+{
+ u32 reg;
+
+ writel(cmd, i2c->regs + MXS_I2C_CTRL0);
+
+ /* readback makes sure the write is latched into hardware */
+ reg = readl(i2c->regs + MXS_I2C_CTRL0);
+ reg |= MXS_I2C_CTRL0_RUN;
+ writel(reg, i2c->regs + MXS_I2C_CTRL0);
+}
+
static int mxs_i2c_pio_setup_xfer(struct i2c_adapter *adap,
struct i2c_msg *msg, uint32_t flags)
{
@@ -341,23 +385,26 @@ static int mxs_i2c_pio_setup_xfer(struct i2c_adapter *adap,
addr_data |= I2C_SMBUS_READ;
/* SELECT command. */
- writel(MXS_I2C_CTRL0_RUN | MXS_CMD_I2C_SELECT,
- i2c->regs + MXS_I2C_CTRL0);
+ mxs_i2c_pio_trigger_cmd(i2c, MXS_CMD_I2C_SELECT);
ret = mxs_i2c_pio_wait_dmareq(i2c);
if (ret)
return ret;
writel(addr_data, i2c->regs + MXS_I2C_DATA);
+ writel(MXS_I2C_DEBUG0_DMAREQ, i2c->regs + MXS_I2C_DEBUG0_CLR);
- ret = mxs_i2c_pio_wait_cplt(i2c);
+ ret = mxs_i2c_pio_wait_cplt(i2c, 0);
if (ret)
return ret;
+ if (mxs_i2c_pio_check_error_state(i2c))
+ goto cleanup;
+
/* READ command. */
- writel(MXS_I2C_CTRL0_RUN | MXS_CMD_I2C_READ | flags |
- MXS_I2C_CTRL0_XFER_COUNT(msg->len),
- i2c->regs + MXS_I2C_CTRL0);
+ mxs_i2c_pio_trigger_cmd(i2c,
+ MXS_CMD_I2C_READ | flags |
+ MXS_I2C_CTRL0_XFER_COUNT(msg->len));
for (i = 0; i < msg->len; i++) {
if ((i & 3) == 0) {
@@ -365,6 +412,8 @@ static int mxs_i2c_pio_setup_xfer(struct i2c_adapter *adap,
if (ret)
return ret;
data = readl(i2c->regs + MXS_I2C_DATA);
+ writel(MXS_I2C_DEBUG0_DMAREQ,
+ i2c->regs + MXS_I2C_DEBUG0_CLR);
}
msg->buf[i] = data & 0xff;
data >>= 8;
@@ -373,9 +422,9 @@ static int mxs_i2c_pio_setup_xfer(struct i2c_adapter *adap,
addr_data |= I2C_SMBUS_WRITE;
/* WRITE command. */
- writel(MXS_I2C_CTRL0_RUN | MXS_CMD_I2C_WRITE | flags |
- MXS_I2C_CTRL0_XFER_COUNT(msg->len + 1),
- i2c->regs + MXS_I2C_CTRL0);
+ mxs_i2c_pio_trigger_cmd(i2c,
+ MXS_CMD_I2C_WRITE | flags |
+ MXS_I2C_CTRL0_XFER_COUNT(msg->len + 1));
/*
* The LSB of data buffer is the first byte blasted across
@@ -391,6 +440,8 @@ static int mxs_i2c_pio_setup_xfer(struct i2c_adapter *adap,
if (ret)
return ret;
writel(data, i2c->regs + MXS_I2C_DATA);
+ writel(MXS_I2C_DEBUG0_DMAREQ,
+ i2c->regs + MXS_I2C_DEBUG0_CLR);
}
}
@@ -401,13 +452,19 @@ static int mxs_i2c_pio_setup_xfer(struct i2c_adapter *adap,
if (ret)
return ret;
writel(data, i2c->regs + MXS_I2C_DATA);
+ writel(MXS_I2C_DEBUG0_DMAREQ,
+ i2c->regs + MXS_I2C_DEBUG0_CLR);
}
}
- ret = mxs_i2c_pio_wait_cplt(i2c);
+ ret = mxs_i2c_pio_wait_cplt(i2c, flags & MXS_I2C_CTRL0_POST_SEND_STOP);
if (ret)
return ret;
+ /* make sure we capture any occurred error into cmd_err */
+ mxs_i2c_pio_check_error_state(i2c);
+
+cleanup:
/* Clear any dangling IRQs and re-enable interrupts. */
writel(MXS_I2C_IRQ_MASK, i2c->regs + MXS_I2C_CTRL1_CLR);
writel(MXS_I2C_IRQ_MASK << 8, i2c->regs + MXS_I2C_CTRL1_SET);
@@ -439,12 +496,12 @@ static int mxs_i2c_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg,
* using PIO mode while longer transfers use DMA. The 8 byte border is
* based on this empirical measurement and a lot of previous frobbing.
*/
+ i2c->cmd_err = 0;
if (msg->len < 8) {
ret = mxs_i2c_pio_setup_xfer(adap, msg, flags);
if (ret)
mxs_i2c_reset(i2c);
} else {
- i2c->cmd_err = 0;
INIT_COMPLETION(i2c->cmd_complete);
ret = mxs_i2c_dma_setup_xfer(adap, msg, flags);
if (ret)
@@ -454,13 +511,19 @@ static int mxs_i2c_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg,
msecs_to_jiffies(1000));
if (ret == 0)
goto timeout;
+ }
- if (i2c->cmd_err == -ENXIO)
- mxs_i2c_reset(i2c);
-
- ret = i2c->cmd_err;
+ if (i2c->cmd_err == -ENXIO) {
+ /*
+ * If the transfer fails with a NAK from the slave the
+ * controller halts until it gets told to return to idle state.
+ */
+ writel(MXS_I2C_CTRL1_CLR_GOT_A_NAK,
+ i2c->regs + MXS_I2C_CTRL1_SET);
}
+ ret = i2c->cmd_err;
+
dev_dbg(i2c->dev, "Done with err=%d\n", ret);
return ret;
@@ -686,11 +749,8 @@ static int mxs_i2c_probe(struct platform_device *pdev)
static int mxs_i2c_remove(struct platform_device *pdev)
{
struct mxs_i2c_dev *i2c = platform_get_drvdata(pdev);
- int ret;
- ret = i2c_del_adapter(&i2c->adapter);
- if (ret)
- return -EBUSY;
+ i2c_del_adapter(&i2c->adapter);
if (i2c->dmach)
dma_release_channel(i2c->dmach);
generated by cgit v1.2.3 (git 2.0.4) at 2024-11-18 00:30:02 +0000