[PATCH v2 12/12] clocksource: samsung-time: Add Device Tree support

[Tomasz Figa <tomasz.figa@gmail.com>]

This patch adds support for parsing all platform-specific data from
Device Tree and instantiation using clocksource_of_init to samsung-time
clocksource driver.

Cc: devicetree-discuss@lists.ozlabs.org
Signed-off-by: Tomasz Figa <tomasz.figa@gmail.com>
---
 .../devicetree/bindings/arm/samsung-timer.txt      |  33 ++++++
 drivers/clocksource/samsung-time.c                 | 113 ++++++++++++++++++++-
 2 files changed, 143 insertions(+), 3 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/arm/samsung-timer.txt

diff --git a/Documentation/devicetree/bindings/arm/samsung-timer.txt b/Documentation/devicetree/bindings/arm/samsung-timer.txt
new file mode 100644
index 0000000..179b7e4
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/samsung-timer.txt
@@ -0,0 +1,33 @@
+* Samsung PWM timer
+
+Samsung SoCs contain PWM timer blocks which can be used for system clock source
+and clock event timers.
+
+Be aware that this configuration is supported only on uniprocessor platforms.
+For SMP SoCs, SMP-aware timers should be used, like MCT.
+
+Required properties:
+- compatible : should be one of following:
+    samsung,s3c24xx-pwm-timer - for 16-bit timers present on S3C24xx
+    samsung,s3c64xx-pwm-timer - for 32-bit timers present on S3C64xx and newer
+- reg: base address and size of register area
+- interrupts: list of timer interrupts (one interrupt per timer, starting at
+  timer 0)
+
+Optional properties:
+- samsung,source-timer: index of timer to be used as clocksource (defaults to 4)
+- samsung,event-timer: index of timer to be used as clock event (defaults to 3)
+- samsung,prescale-divisor: PWM prescaler divisor (from 1 to 256)
+- samsung,divisor: PWM main divider divisor (1, 2, 4, 8 or 16)
+
+Example:
+	timer@7f006000 {
+		compatible = "samsung,s3c64xx-pwm-timer";
+		reg = <0x7f006000 0x1000>;
+		interrupt-parent = <&vic0>;
+		interrupts = <23>, <24>, <25>, <27>, <28>;
+		samsung,source-timer = <4>;
+		samsung,event-timer = <3>;
+		samsung,prescale-divisor = <2>;
+		samsung,divisor = <1>;
+	};
diff --git a/drivers/clocksource/samsung-time.c b/drivers/clocksource/samsung-time.c
index 4134811..76a15ca 100644
--- a/drivers/clocksource/samsung-time.c
+++ b/drivers/clocksource/samsung-time.c
@@ -14,6 +14,9 @@
 #include <linux/err.h>
 #include <linux/clk.h>
 #include <linux/clockchips.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
 #include <linux/platform_device.h>
 
 #include <clocksource/samsung-time.h>
@@ -480,9 +483,12 @@ static void __init samsung_timer_resources(void)
 	unsigned long source_id = timer_source.source_id;
 	char devname[15];
 
-	timer_base = ioremap_nocache(timer_variant.reg_base, SZ_4K);
-	if (!timer_base)
-		panic("failed to map timer registers");
+	if (!timer_base) {
+		/* Compatibility fallback for non-DT platforms */
+		timer_base = ioremap_nocache(timer_variant.reg_base, SZ_4K);
+		if (!timer_base)
+			panic("failed to map timer registers");
+	}
 
 	timerclk = clk_get(NULL, "timers");
 	if (IS_ERR(timerclk))
@@ -515,8 +521,102 @@ static void __init samsung_timer_resources(void)
 	clk_enable(tin_source);
 }
 
+enum {
+	TYPE_S3C24XX,
+	TYPE_S3C64XX,
+};
+
+#ifdef CONFIG_OF
+static const struct of_device_id samsung_timer_ids[] = {
+	{ .compatible = "samsung,s3c24xx-pwm-timer",
+					.data = (void *)TYPE_S3C24XX, },
+	{ .compatible = "samsung,s3c64xx-pwm-timer",
+					.data = (void *)TYPE_S3C64XX, },
+	{},
+};
+
+static void samsung_timer_parse_dt(struct device_node *np,
+					const struct of_device_id *match)
+{
+	int i;
+	u32 val;
+
+	timer_base = of_iomap(np, 0);
+	if (!timer_base)
+		panic("failed to map timer registers");
+
+	for (i = 0; i < SAMSUNG_PWM_NUM; ++i)
+		timer_variant.irqs[i] = irq_of_parse_and_map(np, i);
+
+	if (!timer_variant.irqs[timer_source.event_id])
+		panic("no clock event irq provided");
+
+	switch ((unsigned int)match->data) {
+	case TYPE_S3C24XX:
+		timer_variant.bits = 16;
+		timer_variant.prescale = 25;
+		timer_variant.prescale = 50;
+		timer_variant.has_tint_cstat = false;
+		break;
+	case TYPE_S3C64XX:
+		timer_variant.bits = 32;
+		timer_variant.prescale = 2;
+		timer_variant.divisor = 2;
+		timer_variant.has_tint_cstat = true;
+		break;
+	}
+
+	timer_source.source_id = 4;
+	if (!of_property_read_u32(np, "samsung,source-timer", &val)) {
+		if (val >= SAMSUNG_PWM_NUM)
+			panic("samsung,source-timer property out of range");
+		timer_source.source_id = val;
+	}
+
+	timer_source.event_id = 3;
+	if (!of_property_read_u32(np, "samsung,event-timer", &val)) {
+		if (val >= SAMSUNG_PWM_NUM)
+			panic("samsung,event-timer property out of range");
+		timer_source.event_id = val;
+	}
+
+	if (!of_property_read_u32(np, "samsung,prescale-divisor", &val)) {
+		if (val < 1 || val > 256)
+			panic("samsung,prescale-divisor property out of range");
+		timer_variant.prescale = val;
+	}
+
+	if (!of_property_read_u32(np, "samsung,divisor", &val)) {
+		switch (val) {
+		case 1:
+		case 2:
+		case 4:
+		case 8:
+		case 16:
+			timer_variant.divisor = timer_variant.prescale * val;
+			break;
+		default:
+			panic("invalid value of samsung,divisor property");
+		}
+	}
+}
+#endif
+
 void __init samsung_timer_init(void)
 {
+#ifdef CONFIG_OF
+	struct device_node *np;
+	const struct of_device_id *match;
+
+	if (of_have_populated_dt()) {
+		np = of_find_matching_node_and_match(NULL,
+						samsung_timer_ids, &match);
+		if (!np)
+			panic("timer node not found");
+
+		samsung_timer_parse_dt(np, match);
+	}
+#endif
 	if (!timer_source.source_id && !timer_source.event_id)
 		panic("timer sources not set (see samsung_set_timer_source)!\n");
 
@@ -527,3 +627,10 @@ void __init samsung_timer_init(void)
 	samsung_clockevent_init();
 	samsung_clocksource_init();
 }
+
+#ifdef CONFIG_CLKSRC_OF
+CLOCKSOURCE_OF_DECLARE(s3c24xx_timer,
+			"samsung,s3c24xx-pwm-timer", samsung_timer_init)
+CLOCKSOURCE_OF_DECLARE(s3c64xx_timer,
+			"samsung,s3c64xx-pwm-timer", samsung_timer_init)
+#endif
-- 
1.8.1.2