i2c: nomadik: adopt pinctrl support

Amend the I2C nomadik pin controller to optionally take a pin control
handle and set the state of the pins to:

- "default" on boot, resume and before performing an i2c transfer
- "idle" after initial default, after resume default, and after each
   i2c xfer
- "sleep" on suspend()

This should make it possible to optimize energy usage for the pins
both for the suspend/resume cycle, and for runtime cases inbetween
I2C transfers.

Signed-off-by: Patrice Chotard <patrice.chotard@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
[wsa: fixed braces on one else-branch]
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>

drivers/i2c/busses/i2c-nomadik.c

@@ -26,6 +26,7 @@
 #include <linux/platform_data/i2c-nomadik.h>
 #include <linux/of.h>
 #include <linux/of_i2c.h>
+#include <linux/pinctrl/consumer.h>
 
 #define DRIVER_NAME "nmk-i2c"
 
@@ -147,6 +148,10 @@ struct i2c_nmk_client {
  * @stop: stop condition.
  * @xfer_complete: acknowledge completion for a I2C message.
  * @result: controller propogated result.
+ * @pinctrl: pinctrl handle.
+ * @pins_default: default state for the pins.
+ * @pins_idle: idle state for the pins.
+ * @pins_sleep: sleep state for the pins.
  * @busy: Busy doing transfer.
  */
 struct nmk_i2c_dev {
@@ -160,6 +165,11 @@ struct nmk_i2c_dev {
 	int				stop;
 	struct completion		xfer_complete;
 	int				result;
+	/* Three pin states - default, idle & sleep */
+	struct pinctrl			*pinctrl;
+	struct pinctrl_state		*pins_default;
+	struct pinctrl_state		*pins_idle;
+	struct pinctrl_state		*pins_sleep;
 	bool				busy;
 };
 
@@ -636,6 +646,15 @@ static int nmk_i2c_xfer(struct i2c_adapter *i2c_adap,
 		goto out_clk;
 	}
 
+	/* Optionaly enable pins to be muxed in and configured */
+	if (!IS_ERR(dev->pins_default)) {
+		status = pinctrl_select_state(dev->pinctrl,
+				dev->pins_default);
+		if (status)
+			dev_err(&dev->adev->dev,
+				"could not set default pins\n");
+	}
+
 	status = init_hw(dev);
 	if (status)
 		goto out;
@@ -663,6 +682,15 @@ static int nmk_i2c_xfer(struct i2c_adapter *i2c_adap,
 out:
 	clk_disable_unprepare(dev->clk);
 out_clk:
+	/* Optionally let pins go into idle state */
+	if (!IS_ERR(dev->pins_idle)) {
+		status = pinctrl_select_state(dev->pinctrl,
+				dev->pins_idle);
+		if (status)
+			dev_err(&dev->adev->dev,
+				"could not set pins to idle state\n");
+	}
+
 	pm_runtime_put_sync(&dev->adev->dev);
 
 	dev->busy = false;
@@ -857,15 +885,41 @@ static int nmk_i2c_suspend(struct device *dev)
 {
 	struct amba_device *adev = to_amba_device(dev);
 	struct nmk_i2c_dev *nmk_i2c = amba_get_drvdata(adev);
+	int ret;
 
 	if (nmk_i2c->busy)
 		return -EBUSY;
 
+	if (!IS_ERR(nmk_i2c->pins_sleep)) {
+		ret = pinctrl_select_state(nmk_i2c->pinctrl,
+				nmk_i2c->pins_sleep);
+		if (ret)
+			dev_err(dev, "could not set pins to sleep state\n");
+	}
+
 	return 0;
 }
 
 static int nmk_i2c_resume(struct device *dev)
 {
+	struct amba_device *adev = to_amba_device(dev);
+	struct nmk_i2c_dev *nmk_i2c = amba_get_drvdata(adev);
+	int ret;
+
+	/* First go to the default state */
+	if (!IS_ERR(nmk_i2c->pins_default)) {
+		ret = pinctrl_select_state(nmk_i2c->pinctrl,
+				nmk_i2c->pins_default);
+		if (ret)
+			dev_err(dev, "could not set pins to default state\n");
+	}
+	/* Then let's idle the pins until the next transfer happens */
+	if (!IS_ERR(nmk_i2c->pins_idle)) {
+		ret = pinctrl_select_state(nmk_i2c->pinctrl,
+				nmk_i2c->pins_idle);
+		if (ret)
+			dev_err(dev, "could not set pins to idle state\n");
+	}
 	return 0;
 }
 #else
@@ -953,6 +1007,40 @@ static int nmk_i2c_probe(struct amba_device *adev, const struct amba_id *id)
 	dev->adev = adev;
 	amba_set_drvdata(adev, dev);
 
+	dev->pinctrl = devm_pinctrl_get(&adev->dev);
+	if (IS_ERR(dev->pinctrl)) {
+		ret = PTR_ERR(dev->pinctrl);
+		goto err_pinctrl;
+	}
+
+	dev->pins_default = pinctrl_lookup_state(dev->pinctrl,
+						 PINCTRL_STATE_DEFAULT);
+	if (IS_ERR(dev->pins_default)) {
+		dev_err(&adev->dev, "could not get default pinstate\n");
+	} else {
+		ret = pinctrl_select_state(dev->pinctrl,
+					   dev->pins_default);
+		if (ret)
+			dev_dbg(&adev->dev, "could not set default pinstate\n");
+	}
+
+	dev->pins_idle = pinctrl_lookup_state(dev->pinctrl,
+					      PINCTRL_STATE_IDLE);
+	if (IS_ERR(dev->pins_idle)) {
+		dev_dbg(&adev->dev, "could not get idle pinstate\n");
+	} else {
+		/* If possible, let's go to idle until the first transfer */
+		ret = pinctrl_select_state(dev->pinctrl,
+					   dev->pins_idle);
+		if (ret)
+			dev_dbg(&adev->dev, "could not set idle pinstate\n");
+	}
+
+	dev->pins_sleep = pinctrl_lookup_state(dev->pinctrl,
+					       PINCTRL_STATE_SLEEP);
+	if (IS_ERR(dev->pins_sleep))
+		dev_dbg(&adev->dev, "could not get sleep pinstate\n");
+
 	dev->virtbase = ioremap(adev->res.start, resource_size(&adev->res));
 	if (!dev->virtbase) {
 		ret = -ENOMEM;
@@ -1022,6 +1110,7 @@ static int nmk_i2c_probe(struct amba_device *adev, const struct amba_id *id)
  err_no_ioremap:
 	amba_set_drvdata(adev, NULL);
 	kfree(dev);
+ err_pinctrl:
  err_no_mem:
 
 	return ret;