[PATCH] i2c: imx: check busy bit when START/STOP

[Richard Zhao <linuxzsc-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

After START, wait busy bit to be set and
after STOP, wait busy bit to be clear.

Disable clock when it's possible to save power.

Signed-off-by: Richard Zhao <linuxzsc-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
 drivers/i2c/busses/i2c-imx.c |  116 ++++++++++++++++++++++++++++++++----------
 1 files changed, 88 insertions(+), 28 deletions(-)

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 4afba3e..59cde70 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -120,19 +120,40 @@ struct imx_i2c_struct {
 	wait_queue_head_t	queue;
 	unsigned long		i2csr;
 	unsigned int 		disable_delay;
+	unsigned int		ifdr; /* IMX_I2C_IFDR */
 };

 /** Functions for IMX I2C adapter driver
***************************************
 *******************************************************************************/

-static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx)
+#ifdef CONFIG_I2C_DEBUG_BUS
+#define reg_dump(i2c_imx) \
+{ \
+	printk(KERN_DEBUG "fun %s:%d ", __func__, __LINE__); \
+	printk(KERN_DEBUG "IADR %02x IFDR %02x I2CR %02x I2SR %02x\n", \
+		readb(i2c_imx->base + IMX_I2C_IADR), \
+		readb(i2c_imx->base + IMX_I2C_IFDR), \
+		readb(i2c_imx->base + IMX_I2C_I2CR), \
+		readb(i2c_imx->base + IMX_I2C_I2SR)); \
+}
+#else
+#define reg_dump(i2c_imx)
+#endif
+
+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) {
+	temp = readb(i2c_imx->base + IMX_I2C_I2SR);
+	while (1) {
+		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__);
@@ -141,9 +162,11 @@ static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx)
 		if (time_after(jiffies, orig_jiffies + HZ / 1000)) {
 			dev_dbg(&i2c_imx->adapter.dev,
 				"<%s> I2C bus is busy\n", __func__);
+			reg_dump(i2c_imx);
 			return -EIO;
 		}
 		schedule();
+		temp = readb(i2c_imx->base + IMX_I2C_I2SR);
 	}

 	return 0;
@@ -158,9 +181,11 @@ static int i2c_imx_trx_complete(struct
imx_i2c_struct *i2c_imx)

 	if (unlikely(result < 0)) {
 		dev_dbg(&i2c_imx->adapter.dev, "<%s> result < 0\n", __func__);
+		reg_dump(i2c_imx);
 		return result;
 	} else if (unlikely(!(i2c_imx->i2csr & I2SR_IIF))) {
 		dev_dbg(&i2c_imx->adapter.dev, "<%s> Timeout\n", __func__);
+		reg_dump(i2c_imx);
 		return -ETIMEDOUT;
 	}
 	dev_dbg(&i2c_imx->adapter.dev, "<%s> TRX complete\n", __func__);
@@ -172,6 +197,7 @@ static int i2c_imx_acked(struct imx_i2c_struct *i2c_imx)
 {
 	if (readb(i2c_imx->base + IMX_I2C_I2SR) & I2SR_RXAK) {
 		dev_dbg(&i2c_imx->adapter.dev, "<%s> No ACK\n", __func__);
+		reg_dump(i2c_imx);
 		return -EIO;  /* No ACK */
 	}

@@ -179,20 +205,37 @@ 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__);

+	clk_enable(i2c_imx->clk);
+	writeb(i2c_imx->ifdr, i2c_imx->base + IMX_I2C_IFDR);
 	/* Enable I2C controller */
+	writeb(0, i2c_imx->base + IMX_I2C_I2SR);
 	writeb(I2CR_IEN, i2c_imx->base + IMX_I2C_I2CR);
+
+	result = i2c_imx_bus_busy(i2c_imx, 0);
+	if (result) {
+		reg_dump(i2c_imx);
+		return result;
+	}
+
 	/* 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) {
+		reg_dump(i2c_imx);
+		return result;
+	}
 	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)
@@ -202,18 +245,21 @@ static void i2c_imx_stop(struct imx_i2c_struct *i2c_imx)
 	/* Stop I2C transaction */
 	dev_dbg(&i2c_imx->adapter.dev, "<%s>\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);
-	/* setup chip registers to defaults */
-	writeb(I2CR_IEN, i2c_imx->base + IMX_I2C_I2CR);
-	writeb(0, i2c_imx->base + IMX_I2C_I2SR);
 	/*
 	 * 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_bus_busy(i2c_imx, 0))
+		reg_dump(i2c_imx);
+
 	/* Disable I2C controller */
 	writeb(0, i2c_imx->base + IMX_I2C_I2CR);
+	clk_disable(i2c_imx->clk);
 }

 static void __init i2c_imx_set_clk(struct imx_i2c_struct *i2c_imx,
@@ -233,17 +279,19 @@ static void __init i2c_imx_set_clk(struct
imx_i2c_struct *i2c_imx,
 	else
 		for (i = 0; i2c_clk_div[i][0] < div; i++);

-	/* Write divider value to register */
-	writeb(i2c_clk_div[i][1], i2c_imx->base + IMX_I2C_IFDR);
-
-	/*
-	 * There dummy delay is calculated.
-	 * It should be about one I2C clock period long.
-	 * This delay is used in I2C bus disable function
-	 * to fix chip hardware bug.
-	 */
-	i2c_imx->disable_delay = (500000U * i2c_clk_div[i][0]
-		+ (i2c_clk_rate / 2) - 1) / (i2c_clk_rate / 2);
+	/* Store divider value */
+	i2c_imx->ifdr = i2c_clk_div[i][1];
+
+	if (cpu_is_mx1()) {
+		/*
+		 * There dummy delay is calculated.
+		 * It should be about one I2C clock period long.
+		 * This delay is used in I2C bus disable function
+		 * to fix chip hardware bug.
+		 */
+		i2c_imx->disable_delay = (500000U * i2c_clk_div[i][0]
+			+ (i2c_clk_rate / 2) - 1) / (i2c_clk_rate / 2);
+	}

 	/* dev_dbg() can't be used, because adapter is not yet registered */
 #ifdef CONFIG_I2C_DEBUG_BUS
@@ -344,7 +392,7 @@ static int i2c_imx_read(struct imx_i2c_struct
*i2c_imx, struct i2c_msg *msgs)
 			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);
 		} else if (i == (msgs->len - 2)) {
 			dev_dbg(&i2c_imx->adapter.dev,
@@ -369,14 +417,24 @@ static int i2c_imx_xfer(struct i2c_adapter *adapter,
 	struct imx_i2c_struct *i2c_imx = i2c_get_adapdata(adapter);

 	dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__);
-
+#ifdef CONFIG_I2C_DEBUG_BUS
+	for (i = 0; i < num; i++) {
+		printk(KERN_DEBUG "msg%d addr %02x RD %d cnt %d d:", i,
+			msgs[i].addr, msgs[i].flags & I2C_M_RD, msgs[i].len);
+		if (!(msgs[i].flags & I2C_M_RD)) {
+			int j;
+			for (j = 0; j < msgs[i].len; j++)
+				printk("%02x ", msgs[i].buf[j]);
+		}
+		printk("\n");
+	}
+#endif
 	/* Check if i2c bus is not busy */
-	result = i2c_imx_bus_busy(i2c_imx);
-	if (result)
-		goto fail0;

 	/* Start I2C transfer */
-	i2c_imx_start(i2c_imx);
+	result = i2c_imx_start(i2c_imx);
+	if (result)
+		goto fail0;

 	/* read/write data */
 	for (i = 0; i < num; i++) {
@@ -386,6 +444,11 @@ 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) {
+				reg_dump(i2c_imx);
+				goto fail0;
+			}
 		}
 		dev_dbg(&i2c_imx->adapter.dev,
 			"<%s> transfer message: %d\n", __func__, i);
@@ -442,7 +505,7 @@ static int __init i2c_imx_probe(struct
platform_device *pdev)
 	int irq;
 	int ret;

-	dev_dbg(&pdev->dev, "<%s>\n", __func__);
+	dev_info(&pdev->dev, "<%s>\n", __func__);

 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (!res) {
@@ -500,7 +563,6 @@ static int __init i2c_imx_probe(struct
platform_device *pdev)
 		dev_err(&pdev->dev, "can't get I2C clock\n");
 		goto fail3;
 	}
-	clk_enable(i2c_imx->clk);

 	/* Request IRQ */
 	ret = request_irq(i2c_imx->irq, i2c_imx_isr, 0, pdev->name, i2c_imx);
@@ -549,7 +611,6 @@ static int __init i2c_imx_probe(struct
platform_device *pdev)
 fail5:
 	free_irq(i2c_imx->irq, i2c_imx);
 fail4:
-	clk_disable(i2c_imx->clk);
 	clk_put(i2c_imx->clk);
 fail3:
 	release_mem_region(i2c_imx->res->start, resource_size(res));
@@ -587,7 +648,6 @@ static int __exit i2c_imx_remove(struct
platform_device *pdev)
 		pdata->exit(&pdev->dev);

 	/* Disable I2C clock */
-	clk_disable(i2c_imx->clk);
 	clk_put(i2c_imx->clk);

 	release_mem_region(i2c_imx->res->start, resource_size(i2c_imx->res));
-- 
1.6.0.4