On 26/06/11 09:09, Grant Likely wrote:

On Fri, Jun 24, 2011 at 03:10:59PM +0100, Marc Zyngier wrote:

quoted

Add device tree support to the arm_smp_twd driver.

The DT bindings for the TWD are defined as such:
- one timer node per CPU, using corresponding PPI
  interrupt controller
- provides both timer and watchdog interrupt

Tested on RealView PB11MPCore and VExpress.

Signed-off-by: Marc Zyngier <redacted>
---
 Documentation/devicetree/bindings/arm/twd.txt |   54 ++++++++++++++
 drivers/clocksource/arm_smp_twd.c             |   92 +++++++++++++++++++++---
 2 files changed, 134 insertions(+), 12 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/arm/twd.txt

diff --git a/Documentation/devicetree/bindings/arm/twd.txt b/Documentation/devicetree/bindings/arm/twd.txt
new file mode 100644
index 0000000..3823a81
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/twd.txt

@@ -0,0 +1,54 @@
+* ARM Timer Watchdog
+
+ARM SMP cores are often associated with a TWD providing a per-cpu timer
+and a per-cpu watchdog. Usually wired to the PPI interface of a GIC.
+
+Main node properties:
+
+- compatible		: "arm,smp-twd", "localtimer"

"localtimer" isn't a very good compatible value.  Compatible is
intended to identify the specific hardware, and "localtimer" is a very
generic name.

This is the early_device class name creeping in. I usually used the
"device_type" property, but been told this wasn't the right way...

Of course, if we get rid of the idea of early devices, this is a moot point.

Also, as commented on for the gic, I'd like to see some level of
versioning on the arm,smp-twd string.

There's only one version of TWD at the moment, so I guess I'll tie it to
the CPU core implementation, e.g: "arm,twd-11mpcore", "arm,twd-cortex-a9"...

quoted

+- reg			: register mapping for the registers.
+- #address-cells	: <1>
+- #size-cells		: <0>
+
+Timer sub nodes (one per CPU)
+
+- interrupt-parent	: phandle to the corresponding gic-ppi.
+- interrupts		: <IRQtimer IRQwatchdog> (usually <29 30>)
+- reg			: index of the CPU this timer is connected to.
+
+Example (ARM RealView PB11-MPCore):
+
+localtimer at 1f000600 {
+	compatible = "arm,smp-twd", "localtimer";
+	reg = <0x1f000600 0x100>;
+	#address-cells = <1>;
+	#size-cells = <0>;
+
+	/*
+	 * One timer per CPU, bound to the corresponding
+	 * PPI interface.
+	 */
+	timer at 0 {
+		interrupt-parent = <&gic0ppi0>;
+		interrupts = <29 30>;
+		reg = <0>;
+	};
+
+	timer at 1 {
+		interrupt-parent = <&gic0ppi1>;
+		interrupts = <29 30>;
+		reg = <1>;
+	};
+
+	timer at 2 {
+		interrupt-parent = <&gic0ppi2>;
+		interrupts = <29 30>;
+		reg = <2>;
+	};
+
+	timer at 3 {
+		interrupt-parent = <&gic0ppi3>;
+		interrupts = <29 30>;
+		reg = <3>;
+	};
+};

diff --git a/drivers/clocksource/arm_smp_twd.c b/drivers/clocksource/arm_smp_twd.c
index 65f4669..586acad 100644
--- a/drivers/clocksource/arm_smp_twd.c
+++ b/drivers/clocksource/arm_smp_twd.c

@@ -19,6 +19,9 @@
 #include <linux/interrupt.h>
 #include <linux/ioport.h>
 #include <linux/platform_device.h>
+#include <linux/of_platform.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
 #include <linux/clk.h>
 #include <linux/cpufreq.h>
 #include <linux/err.h>

@@ -37,11 +40,11 @@
 #define TWD_TIMER_CONTROL_IT_ENABLE	(1 << 2)
 
 static void __iomem *twd_base;
-static int twd_ppi;
 
 static struct clk *twd_clk;
 static unsigned long twd_timer_rate;
 static DEFINE_PER_CPU(bool, irq_reqd);
+static DEFINE_PER_CPU(int, twd_irq);
 static struct clock_event_device __percpu *twd_evt;
 
 static void twd_set_mode(enum clock_event_mode mode,

@@ -223,7 +226,7 @@ static void __cpuinit twd_setup(void *data)
 	clk->rating = 450;
 	clk->set_mode = twd_set_mode;
 	clk->set_next_event = twd_set_next_event;
-	clk->irq = gic_ppi_to_vppi(twd_ppi);
+	clk->irq = __get_cpu_var(twd_irq);
 	clk->cpumask = cpumask_of(smp_processor_id());
 
 	pr_debug("Configuring %s on cpu #%d\n", clk->name, smp_processor_id());

@@ -290,31 +293,90 @@ static struct notifier_block __cpuinitdata twd_cpu_nb = {
 	.notifier_call = twd_cpu_notify,
 };
 
-static int twd_probe(struct platform_device *pdev)
+#ifdef CONFIG_OF
+static struct device_node *twd_get_timer_node(struct device_node *twd_np,
+					      struct device_node *child,
+					      int *timer_nr)
+{
+	child = of_get_next_child(twd_np, child);
+	if (child) {
+		const __be32 *reg;
+		reg = of_get_property(child, "reg", NULL);
+		if (!reg)
+			*timer_nr = -1;
+		else
+			*timer_nr = be32_to_cpu(*reg);

There's a new function that should be done and merged in time for
v3.1 that will help with reading properties.  Keep an eye out for
of_getprop_u32()

Yup, spotted. Will use it as soon as it appears in a tree nearby.

	M.
-- 
Jazz is not dead. It just smells funny...