[PATCH 4/6] ARM: S3C2410: I2C driver polling mode support

[vasanthananthan@gmail.com (Vasanth Ananthan)]

This patch adds polling mode support for i2c s3c-2410 driver.
The I2C_SATAPHY controller lacks an interrupt line but the s3c-2410 driver
is interrupt driven. Hence this support is required for functioning
of the I2C_SATAPHY controller.

Signed-off-by: Vasanth Ananthan <vasanth.a@samsung.com>
---
 drivers/i2c/busses/i2c-s3c2410.c |   84 +++++++++++++++++++++++++++++---------
 1 files changed, 65 insertions(+), 19 deletions(-)

diff --git a/drivers/i2c/busses/i2c-s3c2410.c b/drivers/i2c/busses/i2c-s3c2410.c
index 5ae3b02..699b530 100644
--- a/drivers/i2c/busses/i2c-s3c2410.c
+++ b/drivers/i2c/busses/i2c-s3c2410.c
@@ -48,6 +48,7 @@
 #define QUIRK_S3C2440		(1 << 0)
 #define QUIRK_HDMIPHY		(1 << 1)
 #define QUIRK_NO_GPIO		(1 << 2)
+#define QUIRK_SATAPHY		(1 << 3)
 
 /* i2c controller state */
 enum s3c24xx_i2c_state {
@@ -102,10 +103,14 @@ static struct platform_device_id s3c24xx_driver_ids[] = {
 };
 MODULE_DEVICE_TABLE(platform, s3c24xx_driver_ids);
 
+static int i2c_s3c_irq_nextbyte(struct s3c24xx_i2c *i2c, unsigned long iicstat);
+
 #ifdef CONFIG_OF
 static const struct of_device_id s3c24xx_i2c_match[] = {
 	{ .compatible = "samsung,s3c2410-i2c", .data = (void *)0 },
 	{ .compatible = "samsung,s3c2440-i2c", .data = (void *)QUIRK_S3C2440 },
+	{ .compatible = "samsung,s3c2440-sataphy-i2c",
+	  .data = (void *)(QUIRK_S3C2440|QUIRK_SATAPHY|QUIRK_NO_GPIO) },
 	{ .compatible = "samsung,s3c2440-hdmiphy-i2c",
 	  .data = (void *)(QUIRK_S3C2440 | QUIRK_HDMIPHY | QUIRK_NO_GPIO) },
 	{},
@@ -146,7 +151,8 @@ static inline void s3c24xx_i2c_master_complete(struct s3c24xx_i2c *i2c, int ret)
 	if (ret)
 		i2c->msg_idx = ret;
 
-	wake_up(&i2c->wait);
+	if (!(i2c->quirks & QUIRK_SATAPHY))
+		wake_up(&i2c->wait);
 }
 
 static inline void s3c24xx_i2c_disable_ack(struct s3c24xx_i2c *i2c)
@@ -184,6 +190,21 @@ static inline void s3c24xx_i2c_enable_irq(struct s3c24xx_i2c *i2c)
 }
 
 
+static bool is_ack(struct s3c24xx_i2c *i2c)
+{
+	u32 time_out = i2c->tx_setup;
+	while (--time_out) {
+		if (readl(i2c->regs + S3C2410_IICCON)
+			& S3C2410_IICCON_IRQPEND) {
+			if (!(readl(i2c->regs + S3C2410_IICSTAT)
+				& S3C2410_IICSTAT_LASTBIT))
+				return true;
+		}
+		udelay(time_out);
+	}
+	return false;
+}
+
 /* s3c24xx_i2c_message_start
  *
  * put the start of a message onto the bus
@@ -227,6 +248,21 @@ static void s3c24xx_i2c_message_start(struct s3c24xx_i2c *i2c,
 
 	stat |= S3C2410_IICSTAT_START;
 	writel(stat, i2c->regs + S3C2410_IICSTAT);
+
+	if (i2c->quirks & QUIRK_SATAPHY) {
+
+		while ((i2c->msg_num != 0) && is_ack(i2c)) {
+
+			i2c_s3c_irq_nextbyte(i2c, stat);
+
+			stat = readl(i2c->regs + S3C2410_IICSTAT);
+			if (stat & S3C2410_IICSTAT_ARBITR)
+				dev_err(i2c->dev, "deal with arbitration loss\n");
+
+		}
+
+	}
+
 }
 
 static inline void s3c24xx_i2c_stop(struct s3c24xx_i2c *i2c, int ret)
@@ -552,22 +588,27 @@ static int s3c24xx_i2c_doxfer(struct s3c24xx_i2c *i2c,
 	s3c24xx_i2c_message_start(i2c, msgs);
 	spin_unlock_irq(&i2c->lock);
 
-	timeout = wait_event_timeout(i2c->wait, i2c->msg_num == 0, HZ * 5);
-
 	ret = i2c->msg_idx;
 
-	/* having these next two as dev_err() makes life very
-	 * noisy when doing an i2cdetect */
+	if (!(i2c->quirks & QUIRK_SATAPHY)) {
 
-	if (timeout == 0)
-		dev_dbg(i2c->dev, "timeout\n");
-	else if (ret != num)
-		dev_dbg(i2c->dev, "incomplete xfer (%d)\n", ret);
+		timeout = wait_event_timeout(i2c->wait,
+				i2c->msg_num == 0, HZ * 5);
 
-	/* ensure the stop has been through the bus */
+		/* having these next two as dev_err() makes life very
+		* noisy when doing an i2cdetect */
+
+		if (timeout == 0)
+			dev_dbg(i2c->dev, "timeout\n");
+		else if (ret != num)
+			dev_dbg(i2c->dev, "incomplete xfer (%d)\n", ret);
+
+		/* ensure the stop has been through the bus */
+	}
 
 	dev_dbg(i2c->dev, "waiting for bus idle\n");
 
+
 	/* first, try busy waiting briefly */
 	do {
 		cpu_relax();
@@ -710,6 +751,9 @@ static int s3c24xx_i2c_clockrate(struct s3c24xx_i2c *i2c, unsigned int *got)
 	if (div1 == 512)
 		iiccon |= S3C2410_IICCON_TXDIV_512;
 
+	if (i2c->quirks & QUIRK_SATAPHY)
+		iiccon |= S3C2410_IICCON_SCALE(2);
+
 	writel(iiccon, i2c->regs + S3C2410_IICCON);
 
 	if (i2c->quirks & QUIRK_S3C2440) {
@@ -1023,18 +1067,20 @@ static int s3c24xx_i2c_probe(struct platform_device *pdev)
 	 * ensure no current IRQs pending
 	 */
 
-	i2c->irq = ret = platform_get_irq(pdev, 0);
-	if (ret <= 0) {
-		dev_err(&pdev->dev, "cannot find IRQ\n");
-		goto err_iomap;
-	}
+	if (!(i2c->quirks & QUIRK_SATAPHY)) {
+		i2c->irq = ret = platform_get_irq(pdev, 0);
+		if (ret <= 0) {
+			dev_err(&pdev->dev, "cannot find IRQ\n");
+			goto err_iomap;
+		}
 
-	ret = request_irq(i2c->irq, s3c24xx_i2c_irq, 0,
+		ret = request_irq(i2c->irq, s3c24xx_i2c_irq, 0,
 			  dev_name(&pdev->dev), i2c);
 
-	if (ret != 0) {
-		dev_err(&pdev->dev, "cannot claim IRQ %d\n", i2c->irq);
-		goto err_iomap;
+		if (ret != 0) {
+			dev_err(&pdev->dev, "cannot claim IRQ %d\n", i2c->irq);
+			goto err_iomap;
+		}
 	}
 
 	ret = s3c24xx_i2c_register_cpufreq(i2c);
-- 
1.7.5.4