[PATCH 11/11] i2c: omap: enhance pinctrl support

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Amend the I2C omap 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()

By optionally putting the pins into sleep state in the suspend callback
we can accomplish two things.
- One is to minimize current leakage from pins and thus save power,
- second, we can prevent the IP from driving pins output in an
uncontrolled manner, which may happen if the power domain drops the
domain regulator.

Note:
A .suspend & .resume callback is added which simply puts the pins to sleep
state upon suspend & are moved to default & idle state upon resume.

If any of the above pin states are missing in dt, a warning message
about the missing state is displayed.
If certain pin-states are not available, to remove this warning message
pass respective state name with null phandler.

(Changes based on i2c-nomadik.c)

Signed-off-by: Hebbar Gururaja <gururaja.hebbar@xxxxxx>
Cc: Tony Lindgren <tony@xxxxxxxxxxx>
Cc: Wolfram Sang <wsa@xxxxxxxxxxxxx>
Cc: linux-omap@xxxxxxxxxxxxxxx
Cc: linux-i2c@xxxxxxxxxxxxxxx
---
:100644 100644 e02f9e3... 588ba28... M	drivers/i2c/busses/i2c-omap.c
 drivers/i2c/busses/i2c-omap.c |  112 ++++++++++++++++++++++++++++++++++++++---
 1 file changed, 105 insertions(+), 7 deletions(-)

diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
index e02f9e3..588ba28 100644
--- a/drivers/i2c/busses/i2c-omap.c
+++ b/drivers/i2c/busses/i2c-omap.c
@@ -214,7 +214,11 @@ struct omap_i2c_dev {
 	u16			westate;
 	u16			errata;
 
-	struct pinctrl		*pins;
+	/* Three pin states - default, idle & sleep */
+	struct pinctrl			*pinctrl;
+	struct pinctrl_state		*pins_default;
+	struct pinctrl_state		*pins_idle;
+	struct pinctrl_state		*pins_sleep;
 };
 
 static const u8 reg_map_ip_v1[] = {
@@ -641,6 +645,11 @@ omap_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
 	if (IS_ERR_VALUE(r))
 		goto out;
 
+	/* Optionaly enable pins to be muxed in and configured */
+	if (!IS_ERR(dev->pins_default))
+		if (pinctrl_select_state(dev->pinctrl, dev->pins_default))
+			dev_err(dev->dev, "could not set default pins\n");
+
 	r = omap_i2c_wait_for_bb(dev);
 	if (r < 0)
 		goto out;
@@ -664,7 +673,13 @@ omap_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
 
 out:
 	pm_runtime_mark_last_busy(dev->dev);
+
 	pm_runtime_put_autosuspend(dev->dev);
+	/* Optionally let pins go into idle state */
+	if (!IS_ERR(dev->pins_idle))
+		if (pinctrl_select_state(dev->pinctrl, dev->pins_idle))
+			dev_err(dev->dev, "could not set pins to idle state\n");
+
 	return r;
 }
 
@@ -1123,14 +1138,47 @@ omap_i2c_probe(struct platform_device *pdev)
 		dev->set_mpu_wkup_lat = pdata->set_mpu_wkup_lat;
 	}
 
-	dev->pins = devm_pinctrl_get_select_default(&pdev->dev);
-	if (IS_ERR(dev->pins)) {
-		if (PTR_ERR(dev->pins) == -EPROBE_DEFER)
+	dev->pinctrl = devm_pinctrl_get(&pdev->dev);
+	if (!IS_ERR(dev->pinctrl)) {
+		dev->pins_default = pinctrl_lookup_state(dev->pinctrl,
+							 PINCTRL_STATE_DEFAULT);
+		if (IS_ERR(dev->pins_default))
+			dev_dbg(&pdev->dev, "could not get default pinstate\n");
+		else
+			if (pinctrl_select_state(dev->pinctrl,
+						 dev->pins_default))
+				dev_err(&pdev->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(&pdev->dev, "could not get idle pinstate\n");
+		else
+			/* If possible, let's idle until the first transfer */
+			if (pinctrl_select_state(dev->pinctrl, dev->pins_idle))
+				dev_err(&pdev->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(&pdev->dev, "could not get sleep pinstate\n");
+	} else {
+		if (PTR_ERR(dev->pinctrl) == -EPROBE_DEFER)
 			return -EPROBE_DEFER;
 
-		dev_warn(&pdev->dev, "did not get pins for i2c error: %li\n",
-			 PTR_ERR(dev->pins));
-		dev->pins = NULL;
+		/*
+		* Since we continue even when pinctrl node is not found,
+		* Invalidate pins as not available. This is to make sure that
+		* IS_ERR(pins_xxx) results in failure when used.
+		*/
+		dev->pins_default = ERR_PTR(-ENODATA);
+		dev->pins_idle = ERR_PTR(-ENODATA);
+		dev->pins_sleep = ERR_PTR(-ENODATA);
+
+		dev_dbg(&pdev->dev, "did not get pins for i2c error: %li\n",
+			PTR_ERR(dev->pinctrl));
 	}
 
 	dev->dev = &pdev->dev;
@@ -1300,6 +1348,10 @@ static int omap_i2c_runtime_suspend(struct device *dev)
 		omap_i2c_read_reg(_dev, OMAP_I2C_STAT_REG);
 	}
 
+	if (!IS_ERR(_dev->pins_idle))
+		if (pinctrl_select_state(_dev->pinctrl, _dev->pins_idle))
+			dev_err(dev, "could not set pins to idle state\n");
+
 	return 0;
 }
 
@@ -1311,13 +1363,59 @@ static int omap_i2c_runtime_resume(struct device *dev)
 	if (!_dev->regs)
 		return 0;
 
+	/* Optionally place the pins to the default state */
+	if (!IS_ERR(_dev->pins_default))
+		if (pinctrl_select_state(_dev->pinctrl, _dev->pins_default))
+			dev_err(dev, "could not set pins to default state\n");
+
 	__omap_i2c_init(_dev);
 
 	return 0;
 }
 #endif /* CONFIG_PM_RUNTIME */
 
+#ifdef CONFIG_PM_SLEEP
+static int omap_i2c_suspend(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct omap_i2c_dev *_dev = platform_get_drvdata(pdev);
+
+	pm_runtime_get_sync(dev);
+	if (omap_i2c_wait_for_bb(_dev) < 0) {
+		pm_runtime_put_sync(dev);
+		return -EBUSY;
+	}
+	pm_runtime_put_sync(dev);
+
+	if (!IS_ERR(_dev->pins_sleep))
+		if (pinctrl_select_state(_dev->pinctrl, _dev->pins_sleep))
+			dev_err(dev, "could not set pins to sleep state\n");
+
+	return 0;
+}
+
+static int omap_i2c_resume(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct omap_i2c_dev *_dev = platform_get_drvdata(pdev);
+
+	/* First go to the default state */
+	if (!IS_ERR(_dev->pins_default))
+		if (pinctrl_select_state(_dev->pinctrl, _dev->pins_default))
+			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(_dev->pins_idle))
+		if (pinctrl_select_state(_dev->pinctrl, _dev->pins_idle))
+			dev_err(dev, "could not set pins to idle state\n");
+
+	return 0;
+}
+#endif
+
+
 static struct dev_pm_ops omap_i2c_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(omap_i2c_suspend, omap_i2c_resume)
 	SET_RUNTIME_PM_OPS(omap_i2c_runtime_suspend,
 			   omap_i2c_runtime_resume, NULL)
 };
-- 
1.7.9.5

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