Re: [PATCH v3] ARM: at91: pit add DT support

From: Jean-Christophe PLAGNIOL-VILLARD <plagnioj-sclMFOaUSTBWk0Htik3J/w@public.gmane.org>

Retreive registers address and IRQ from device tree entry. Fall back
to built-in values if an error occurs.

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj-sclMFOaUSTBWk0Htik3J/w@public.gmane.org>
[nicolas.ferre-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org: change error path and interrupts property handling]
Signed-off-by: Nicolas Ferre <redacted>
---
v3: - use irq_of_parse_and_map() for handling irq numbers specified by DT.
      Correction proposed by Jamie Iles.

v2: - new specification of irq numbers in DT (due to modification of AIC code)
    - new error path in of_at91sam926x_pit_init()
    - fall back to built-in values if an error occurs
    - use of of_property_read_u32() to get irq property

 .../devicetree/bindings/arm/atmel-at91.txt         |    8 +++
 arch/arm/boot/dts/at91sam9g20.dtsi                 |    5 ++
 arch/arm/boot/dts/at91sam9g45.dtsi                 |    6 ++
 arch/arm/mach-at91/at91sam926x_time.c              |   53 +++++++++++++++++++-
 4 files changed, 70 insertions(+), 2 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/arm/atmel-at91.txt

diff --git a/Documentation/devicetree/bindings/arm/atmel-at91.txt b/Documentation/devicetree/bindings/arm/atmel-at91.txt
new file mode 100644
index 0000000..380f711
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/atmel-at91.txt

@@ -0,0 +1,8 @@
+Atmel AT91 device tree bindings.
+================================
+
+PIT Timer required properties:
+- compatible: Should be "atmel,at91sam9260-pit"
+- reg: Should contain registers location and length
+- interrupts: Should contain interrupt for the PIT which is the IRQ line
+  shared across all System Controller members.

diff --git a/arch/arm/boot/dts/at91sam9g20.dtsi b/arch/arm/boot/dts/at91sam9g20.dtsi
index 0d21872..5c4be7e 100644
--- a/arch/arm/boot/dts/at91sam9g20.dtsi
+++ b/arch/arm/boot/dts/at91sam9g20.dtsi

@@ -57,6 +57,11 @@
 				reg = <0xfffff000 0x200>;
 			};
 
+			pit: timer@fffffd30 {
+				compatible = "atmel,at91sam9260-pit";
+				reg = <0xfffffd30 0xf>;
+				interrupts = <1 4>;
+			};
 
 			pioA: gpio@fffff400 {
 				compatible = "atmel,at91rm9200-gpio";

diff --git a/arch/arm/boot/dts/at91sam9g45.dtsi b/arch/arm/boot/dts/at91sam9g45.dtsi
index b977a79..0d21c8e 100644
--- a/arch/arm/boot/dts/at91sam9g45.dtsi
+++ b/arch/arm/boot/dts/at91sam9g45.dtsi

@@ -58,6 +58,12 @@
 				reg = <0xfffff000 0x200>;
 			};
 
+			pit: timer@fffffd30 {
+				compatible = "atmel,at91sam9260-pit";
+				reg = <0xfffffd30 0xf>;
+				interrupts = <1 4>;
+			};
+
 			dma: dma-controller@ffffec00 {
 				compatible = "atmel,at91sam9g45-dma";
 				reg = <0xffffec00 0x200>;

diff --git a/arch/arm/mach-at91/at91sam926x_time.c b/arch/arm/mach-at91/at91sam926x_time.c
index d89ead7..534a992 100644
--- a/arch/arm/mach-at91/at91sam926x_time.c
+++ b/arch/arm/mach-at91/at91sam926x_time.c

@@ -14,6 +14,9 @@
 #include <linux/kernel.h>
 #include <linux/clk.h>
 #include <linux/clockchips.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
 
 #include <asm/mach/time.h>
 

@@ -133,7 +136,8 @@ static irqreturn_t at91sam926x_pit_interrupt(int irq, void *dev_id)
 static struct irqaction at91sam926x_pit_irq = {
 	.name		= "at91_tick",
 	.flags		= IRQF_SHARED | IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
-	.handler	= at91sam926x_pit_interrupt
+	.handler	= at91sam926x_pit_interrupt,
+	.irq		= AT91_ID_SYS,
 };
 
 static void at91sam926x_pit_reset(void)

@@ -149,6 +153,49 @@ static void at91sam926x_pit_reset(void)
 	pit_write(AT91_PIT_MR, (pit_cycle - 1) | AT91_PIT_PITEN);
 }
 
+#ifdef CONFIG_OF
+static struct of_device_id timer_ids[] = {
+	{ .compatible = "atmel,at91sam9260-pit" },
+	{ /* sentinel */ }
+};
+
+static int __init of_at91sam926x_pit_init(void)
+{
+	struct device_node	*np;
+	int			ret;
+
+	np = of_find_matching_node(NULL, timer_ids);
+	if (!np)
+		goto err;
+
+	pit_base_addr = of_iomap(np, 0);
+	if (!pit_base_addr)
+		goto node_err;
+
+	/* Get the interrupts property */
+	ret = irq_of_parse_and_map(np, 0);
+	if (ret <= 0)
+		goto ioremap_err;