powerpc/8xx: Adding support of IRQ in MPC8xx GPIO

This patch allows the use of IRQ to notify the change of GPIO status
on MPC8xx CPM IO ports. This then allows to associate IRQs to GPIOs
in the Device Tree.

Ex:
	CPM1_PIO_C: gpio-controller@960 {
		#gpio-cells = <2>;
		compatible = "fsl,cpm1-pario-bank-c";
		reg = <0x960 0x10>;
		fsl,cpm1-gpio-irq-mask = <0x0fff>;
		interrupts = <1 2 6 9 10 11 14 15 23 24 26 31>;
		interrupt-parent = <&CPM_PIC>;
		gpio-controller;
	};

The property 'fsl,cpm1-gpio-irq-mask' defines which of the 16 GPIOs
have the associated interrupts defined in the 'interrupts' property.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Scott Wood <oss@buserror.net>

Documentation/devicetree/bindings/soc/fsl/cpm_qe/gpio.txt

@@ -13,8 +13,17 @@ Required properties:
 - #gpio-cells : Should be two. The first cell is the pin number and the
   second cell is used to specify optional parameters (currently unused).
 - gpio-controller : Marks the port as GPIO controller.
+Optional properties:
+- fsl,cpm1-gpio-irq-mask : For banks having interrupt capability (like port C
+  on CPM1), this item tells which ports have an associated interrupt (ports are
+  listed in the same order as in PCINT register)
+- interrupts : This property provides the list of interrupt for each GPIO having
+  one as described by the fsl,cpm1-gpio-irq-mask property. There should be as
+  many interrupts as number of ones in the mask property. The first interrupt in
+  the list corresponds to the most significant bit of the mask.
+- interrupt-parent : Parent for the above interrupt property.
 
-Example of three SOC GPIO banks defined as gpio-controller nodes:
+Example of four SOC GPIO banks defined as gpio-controller nodes:
 
 	CPM1_PIO_A: gpio-controller@950 {
 		#gpio-cells = <2>;
@@ -30,6 +39,16 @@ Example of three SOC GPIO banks defined as gpio-controller nodes:
 		gpio-controller;
 	};
 
+	CPM1_PIO_C: gpio-controller@960 {
+		#gpio-cells = <2>;
+		compatible = "fsl,cpm1-pario-bank-c";
+		reg = <0x960 0x10>;
+		fsl,cpm1-gpio-irq-mask = <0x0fff>;
+		interrupts = <1 2 6 9 10 11 14 15 23 24 26 31>;
+		interrupt-parent = <&CPM_PIC>;
+		gpio-controller;
+	};
+
 	CPM1_PIO_E: gpio-controller@ac8 {
 		#gpio-cells = <2>;
 		compatible = "fsl,cpm1-pario-bank-e";

arch/powerpc/include/asm/cpm1.h

@@ -560,6 +560,8 @@ typedef struct risc_timer_pram {
 #define CPM_PIN_SECONDARY 2
 #define CPM_PIN_GPIO      4
 #define CPM_PIN_OPENDRAIN 8
+#define CPM_PIN_FALLEDGE  16
+#define CPM_PIN_ANYEDGE   0
 
 enum cpm_port {
 	CPM_PORTA,

arch/powerpc/sysdev/cpm1.c

@@ -377,6 +377,10 @@ static void cpm1_set_pin16(int port, int pin, int flags)
 			setbits16(&iop->odr_sor, pin);
 		else
 			clrbits16(&iop->odr_sor, pin);
+		if (flags & CPM_PIN_FALLEDGE)
+			setbits16(&iop->intr, pin);
+		else
+			clrbits16(&iop->intr, pin);
 	}
 }
 
@@ -528,6 +532,9 @@ struct cpm1_gpio16_chip {
 
 	/* shadowed data register to clear/set bits safely */
 	u16 cpdata;
+
+	/* IRQ associated with Pins when relevant */
+	int irq[16];
 };
 
 static void cpm1_gpio16_save_regs(struct of_mm_gpio_chip *mm_gc)
@@ -578,6 +585,14 @@ static void cpm1_gpio16_set(struct gpio_chip *gc, unsigned int gpio, int value)
 	spin_unlock_irqrestore(&cpm1_gc->lock, flags);
 }
 
+static int cpm1_gpio16_to_irq(struct gpio_chip *gc, unsigned int gpio)
+{
+	struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
+	struct cpm1_gpio16_chip *cpm1_gc = gpiochip_get_data(&mm_gc->gc);
+
+	return cpm1_gc->irq[gpio] ? : -ENXIO;
+}
+
 static int cpm1_gpio16_dir_out(struct gpio_chip *gc, unsigned int gpio, int val)
 {
 	struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
@@ -618,6 +633,7 @@ int cpm1_gpiochip_add16(struct device_node *np)
 	struct cpm1_gpio16_chip *cpm1_gc;
 	struct of_mm_gpio_chip *mm_gc;
 	struct gpio_chip *gc;
+	u16 mask;
 
 	cpm1_gc = kzalloc(sizeof(*cpm1_gc), GFP_KERNEL);
 	if (!cpm1_gc)
@@ -625,6 +641,14 @@ int cpm1_gpiochip_add16(struct device_node *np)
 
 	spin_lock_init(&cpm1_gc->lock);
 
+	if (!of_property_read_u16(np, "fsl,cpm1-gpio-irq-mask", &mask)) {
+		int i, j;
+
+		for (i = 0, j = 0; i < 16; i++)
+			if (mask & (1 << (15 - i)))
+				cpm1_gc->irq[i] = irq_of_parse_and_map(np, j++);
+	}
+
 	mm_gc = &cpm1_gc->mm_gc;
 	gc = &mm_gc->gc;
 
@@ -634,6 +658,7 @@ int cpm1_gpiochip_add16(struct device_node *np)
 	gc->direction_output = cpm1_gpio16_dir_out;
 	gc->get = cpm1_gpio16_get;
 	gc->set = cpm1_gpio16_set;
+	gc->to_irq = cpm1_gpio16_to_irq;
 
 	return of_mm_gpiochip_add_data(np, mm_gc, cpm1_gc);
 }