[PATCH v3 5/6] ASoC: WM8903: Get default irq_active_low from IRQ controller

[Stephen Warren <swarren-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>]

If the WM8903 is hooked up to an interrupt, set the irq_active_low flag
in the default platform data based on the IRQ's IRQ_TYPE. Map IRQ_TYPE_NONE
(a lack of explicit configuration/restriction) to irq_active_low = false;
the previous default.

This code is mainly added to support device tree interrupt bindings,
although will work perfectly well in a non device tree system too.

Any interrupt controller that supports only a single IRQ_TYPE could
set each IRQ's type based on that restriction. This applies equally
with and without device tree. To cater for interrupt controllers
that don't do this, for which irqd_get_trigger_type() will return
IRQ_TYPE_NONE, the platform data irq_active_low field may be used
in systems that don't use device tree.

With device tree, every IRQ must have some IRQ_TYPE set.

Controllers that support DT and multiple IRQ_TYPEs must define the
interrupts property (as used in interrupt source nodes) such that it
defines the IRQ_TYPE to use. When the core DT setup code initializes
wm8903->irq, the interrupts property will be parsed, and as a side-
effect, set the IRQ's IRQ_TYPE for the WM8903 probe() function to read.

Controllers that support DT and a single IRQ_TYPE could arrange to
set the IRQ_TYPE somehow during their initialization, or hard-code
it during the processing of the child interrupts property.

Signed-off-by: Stephen Warren <swarren-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
---
 sound/soc/codecs/wm8903.c |   28 ++++++++++++++++++++++++++++
 1 files changed, 28 insertions(+), 0 deletions(-)

diff --git a/sound/soc/codecs/wm8903.c b/sound/soc/codecs/wm8903.c
index 38e1137..6797b0a 100644
--- a/sound/soc/codecs/wm8903.c
+++ b/sound/soc/codecs/wm8903.c
@@ -24,6 +24,7 @@
 #include <linux/pm.h>
 #include <linux/i2c.h>
 #include <linux/slab.h>
+#include <linux/irq.h>
 #include <sound/core.h>
 #include <sound/jack.h>
 #include <sound/pcm.h>
@@ -1937,6 +1938,33 @@ static int wm8903_probe(struct snd_soc_codec *codec)
 	defpdata.gpio_base = -1;
 	for (i = 0; i < ARRAY_SIZE(defpdata.gpio_cfg); i++)
 		defpdata.gpio_cfg[i] = 0xffffffff;
+	if (wm8903->irq) {
+		struct irq_data *irq_data = irq_get_irq_data(wm8903->irq);
+		if (!irq_data) {
+			dev_err(codec->dev, "Invalid IRQ: %d\n",
+				wm8903->irq);
+			return -EINVAL;
+		}
+		switch (irqd_get_trigger_type(irq_data)) {
+		case IRQ_TYPE_NONE:
+			/*
+			 * We assume the controller imposes no restrictions,
+			 * so we are able to select active-high
+			 */
+			/* Fall-through */
+		case IRQ_TYPE_LEVEL_HIGH:
+			defpdata.irq_active_low = false;
+			break;
+		case IRQ_TYPE_LEVEL_LOW:
+			defpdata.irq_active_low = true;
+			break;
+		default:
+			dev_err(codec->dev,
+				"Unsupported IRQ_TYPE %x\n",
+				irqd_get_trigger_type(irq_data));
+			return -EINVAL;
+		}
+	}
 
 	/* If no platform data was supplied, use the defaults */
 	if (!pdata)
-- 
1.7.0.4