i2c: nomadic-i2c driver updates for clock and power

This patch is based on the follwoing work:

i2c: I2C now always releases the VAPE power domain
ST-Ericsson ID: AP 272787
Author: Rickard Andersson <rickard.andersson@stericsson.com>

i2c: Using regulator framework to handle power domains
Author: Daniel WILLERUD <daniel.willerud@stericsson.com>

Moreover, driver documentation is added in DocBook

Signed-off-by: Mian Yousaf Kaukab <mian.yousaf.kaukab@stericsson.com>

1 files changed, 40 insertions, 8 deletions

diff --git a/drivers/i2c/busses/i2c-nomadik.c b/drivers/i2c/busses/i2c-nomadik.c
index 73de8ade10b..49a8674070b 100644
--- a/drivers/i2c/busses/i2c-nomadik.c
+++ b/drivers/i2c/busses/i2c-nomadik.c
@@ -22,6 +22,7 @@
 #include <linux/err.h>
 #include <linux/clk.h>
 #include <linux/io.h>
+#include <linux/regulator/consumer.h>
 
 #include <plat/i2c.h>
 
@@ -103,6 +104,9 @@
 /* maximum threshold value */
 #define MAX_I2C_FIFO_THRESHOLD	15
 
+/* delay for i2c transfers */
+#define I2C_DELAY		150
+
 enum i2c_status {
 	I2C_NOP,
 	I2C_ON_GOING,
@@ -118,7 +122,7 @@ enum i2c_operation {
 };
 
 /* controller response timeout in ms */
-#define I2C_TIMEOUT_MS	500
+#define I2C_TIMEOUT_MS	2000
 
 /**
  * struct i2c_nmk_client - client specific data
@@ -160,6 +164,7 @@ struct nmk_i2c_dev {
 	int 				stop;
 	struct completion		xfer_complete;
 	int 				result;
+	struct regulator		*regulator;
 };
 
 /* controller's abort causes */
@@ -250,6 +255,8 @@ static int init_hw(struct nmk_i2c_dev *dev)
 {
 	int stat;
 
+	clk_enable(dev->clk);
+
 	stat = flush_i2c_fifo(dev);
 	if (stat)
 		return stat;
@@ -263,6 +270,9 @@ static int init_hw(struct nmk_i2c_dev *dev)
 
 	dev->cli.operation = I2C_NO_OPERATION;
 
+	clk_disable(dev->clk);
+
+	udelay(I2C_DELAY);
 	return 0;
 }
 
@@ -559,6 +569,11 @@ static int nmk_i2c_xfer(struct i2c_adapter *i2c_adap,
 	if (status)
 		return status;
 
+	if (dev->regulator)
+		regulator_enable(dev->regulator);
+
+	clk_enable(dev->clk);
+
 	/* setup the i2c controller */
 	setup_i2c_controller(dev);
 
@@ -566,7 +581,9 @@ static int nmk_i2c_xfer(struct i2c_adapter *i2c_adap,
 		if (unlikely(msgs[i].flags & I2C_M_TEN)) {
 			dev_err(&dev->pdev->dev, "10 bit addressing"
 					"not supported\n");
-			return -EINVAL;
+
+			status = -EINVAL;
+			goto out;
 		}
 		dev->cli.slave_adr	= msgs[i].addr;
 		dev->cli.buffer		= msgs[i].buf;
@@ -591,10 +608,18 @@ static int nmk_i2c_xfer(struct i2c_adapter *i2c_adap,
 			dev_err(&dev->pdev->dev, "%s\n",
 				cause >= ARRAY_SIZE(abort_causes)
 				? "unknown reason" : abort_causes[cause]);
-			return status;
+
+			goto out;
 		}
-		mdelay(1);
+		udelay(I2C_DELAY);
 	}
+
+out:
+	clk_disable(dev->clk);
+
+	if (dev->regulator)
+		regulator_disable(dev->regulator);
+
 	/* return the no. messages processed */
 	if (status)
 		return status;
@@ -850,6 +875,14 @@ static int __devinit nmk_i2c_probe(struct platform_device *pdev)
 		goto err_irq;
 	}
 
+	dev->regulator = regulator_get(&pdev->dev, "v-i2c");
+	if (IS_ERR(dev->regulator)) {
+		dev_err(&pdev->dev, "could not get i2c regulator\n");
+		ret = PTR_ERR(dev->regulator);
+		dev->regulator = NULL;
+		goto err_no_regulator;
+	}
+
 	dev->clk = clk_get(&pdev->dev, NULL);
 	if (IS_ERR(dev->clk)) {
 		dev_err(&pdev->dev, "could not get i2c clock\n");
@@ -857,8 +890,6 @@ static int __devinit nmk_i2c_probe(struct platform_device *pdev)
 		goto err_no_clk;
 	}
 
-	clk_enable(dev->clk);
-
 	adap = &dev->adap;
 	adap->dev.parent = &pdev->dev;
 	adap->owner	= THIS_MODULE;
@@ -895,10 +926,11 @@ static int __devinit nmk_i2c_probe(struct platform_device *pdev)
 	return 0;
 
  err_init_hw:
-	clk_disable(dev->clk);
  err_add_adap:
 	clk_put(dev->clk);
  err_no_clk:
+	regulator_put(dev->regulator);
+ err_no_regulator:
 	free_irq(dev->irq, dev);
  err_irq:
 	iounmap(dev->virtbase);
@@ -928,8 +960,8 @@ static int __devexit nmk_i2c_remove(struct platform_device *pdev)
 	iounmap(dev->virtbase);
 	if (res)
 		release_mem_region(res->start, resource_size(res));
-	clk_disable(dev->clk);
 	clk_put(dev->clk);
+	regulator_put(dev->regulator);
 	platform_set_drvdata(pdev, NULL);
 	kfree(dev);