i2c: allow specifying separate wakeup interrupt in device tree

Instead of having each i2c driver individually parse device tree data in
case it or platform supports separate wakeup interrupt, and handle
enabling and disabling wakeup interrupts in their power management
routines, let's have i2c core do that for us.

Platforms wishing to specify separate wakeup interrupt for the device
should use named interrupt syntax in their DTSes:

	interrupt-parent = <&intc1>;
	interrupts = <5 0>, <6 0>;
	interrupt-names = "irq", "wakeup";

This patch is inspired by work done by Vignesh R <vigneshr@ti.com> for
pixcir_i2c_ts driver.

Note that the original code tried to preserve any existing wakeup
settings from userspace but was not quite right in that regard:
it would preserve wakeup flag set by userspace upon driver rebinding;
but it would re-arm the wakeup flag if it was disabled by userspace.

We think that resetting the flag upon re-binding the driver is proper
behavior as the driver is responsible for setting up and handling
wakeups.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Tested-by: Vignesh R <vigneshr@ti.com>
[wsa: updated the commit message]
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

Documentation/devicetree/bindings/i2c/i2c.txt

@@ -12,7 +12,7 @@ Required properties
 - compatible      - name of I2C bus controller following generic names
 		    recommended practice.
 
-For other required properties e.g. to describe register sets, interrupts,
+For other required properties e.g. to describe register sets,
 clocks, etc. check the binding documentation of the specific driver.
 
 The cells properties above define that an address of children of an I2C bus
@@ -29,5 +29,17 @@ Optional properties
 These properties may not be supported by all drivers. However, if a driver
 wants to support one of the below features, it should adapt the bindings below.
 
-- clock-frequency	- frequency of bus clock in Hz
+- clock-frequency	- frequency of bus clock in Hz.
 - wakeup-source		- device can be used as a wakeup source.
+
+- interrupts		- interrupts used by the device.
+- interrupt-names	- "irq" and "wakeup" names are recognized by I2C core,
+			  other names are left to individual drivers.
+
+Binding may contain optional "interrupts" property, describing interrupts
+used by the device. I2C core will assign "irq" interrupt (or the very first
+interrupt if not using interrupt names) as primary interrupt for the slave.
+
+Also, if device is marked as a wakeup source, I2C core will set up "wakeup"
+interrupt for the device. If "wakeup" interrupt name is not present in the
+binding, then primary interrupt will be used as wakeup interrupt.

drivers/i2c/i2c-core.c

@@ -48,6 +48,7 @@
 #include <linux/rwsem.h>
 #include <linux/pm_runtime.h>
 #include <linux/pm_domain.h>
+#include <linux/pm_wakeirq.h>
 #include <linux/acpi.h>
 #include <linux/jump_label.h>
 #include <asm/uaccess.h>
@@ -645,11 +646,13 @@ static int i2c_device_probe(struct device *dev)
 	if (!client->irq) {
 		int irq = -ENOENT;
 
-		if (dev->of_node)
-			irq = of_irq_get(dev->of_node, 0);
-		else if (ACPI_COMPANION(dev))
+		if (dev->of_node) {
+			irq = of_irq_get_byname(dev->of_node, "irq");
+			if (irq == -EINVAL || irq == -ENODATA)
+				irq = of_irq_get(dev->of_node, 0);
+		} else if (ACPI_COMPANION(dev)) {
 			irq = acpi_dev_gpio_irq_get(ACPI_COMPANION(dev), 0);
-
+		}
 		if (irq == -EPROBE_DEFER)
 			return irq;
 		if (irq < 0)
@@ -662,23 +665,49 @@ static int i2c_device_probe(struct device *dev)
 	if (!driver->probe || !driver->id_table)
 		return -ENODEV;
 
-	if (!device_can_wakeup(&client->dev))
-		device_init_wakeup(&client->dev,
-					client->flags & I2C_CLIENT_WAKE);
+	if (client->flags & I2C_CLIENT_WAKE) {
+		int wakeirq = -ENOENT;
+
+		if (dev->of_node) {
+			wakeirq = of_irq_get_byname(dev->of_node, "wakeup");
+			if (wakeirq == -EPROBE_DEFER)
+				return wakeirq;
+		}
+
+		device_init_wakeup(&client->dev, true);
+
+		if (wakeirq > 0 && wakeirq != client->irq)
+			status = dev_pm_set_dedicated_wake_irq(dev, wakeirq);
+		else if (client->irq > 0)
+			status = dev_pm_set_wake_irq(dev, wakeirq);
+		else
+			status = 0;
+
+		if (status)
+			dev_warn(&client->dev, "failed to set up wakeup irq");
+	}
+
 	dev_dbg(dev, "probe\n");
 
 	status = of_clk_set_defaults(dev->of_node, false);
 	if (status < 0)
-		return status;
+		goto err_clear_wakeup_irq;
 
 	status = dev_pm_domain_attach(&client->dev, true);
 	if (status != -EPROBE_DEFER) {
 		status = driver->probe(client, i2c_match_id(driver->id_table,
 					client));
 		if (status)
-			dev_pm_domain_detach(&client->dev, true);
+			goto err_detach_pm_domain;
 	}
 
+	return 0;
+
+err_detach_pm_domain:
+	dev_pm_domain_detach(&client->dev, true);
+err_clear_wakeup_irq:
+	dev_pm_clear_wake_irq(&client->dev);
+	device_init_wakeup(&client->dev, false);
 	return status;
 }
 
@@ -698,6 +727,10 @@ static int i2c_device_remove(struct device *dev)
 	}
 
 	dev_pm_domain_detach(&client->dev, true);
+
+	dev_pm_clear_wake_irq(&client->dev);
+	device_init_wakeup(&client->dev, false);
+
 	return status;
 }