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Subject[RFC PATCH] ARM: mach-shmobile: Parse DT to get ARCH timer memory region
Date
From: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>

Don't use hardcoded address, retrieve it from device-tree instead.

And besides, this patch fixes the memory error when running
on top of Xen hypervisor:

(XEN) traps.c:1999:d0v0 HSR=0x93830007 pc=0xc0b097f8 gva=0xf0805000
gpa=0x000000e6080000

Which shows that VCPU0 in Dom0 is trying to access an address in memory
it is not allowed to access (0x000000e6080000).
Put simply, Xen doesn't know that it is a device's register memory
since it wasn't described in a host device tree (which Xen parses)
and as the result this memory region wasn't assigned to Dom0 at
domain creation time.

Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>

---

This patch is meant to get feedback from the community before
proceeding further. If we decide to go this direction, all Gen2
device-trees should be updated (add memory region) before
this patch going in.

e.g. r8a7790.dtsi:

...
timer {
compatible = "arm,armv7-timer";
interrupts-extended = <&gic GIC_PPI 13 (GIC_CPU_MASK_SIMPLE(8) | IRQ_TYPE_LEVEL_LOW)>,
<&gic GIC_PPI 14 (GIC_CPU_MASK_SIMPLE(8) | IRQ_TYPE_LEVEL_LOW)>,
<&gic GIC_PPI 11 (GIC_CPU_MASK_SIMPLE(8) | IRQ_TYPE_LEVEL_LOW)>,
<&gic GIC_PPI 10 (GIC_CPU_MASK_SIMPLE(8) | IRQ_TYPE_LEVEL_LOW)>;
+ reg = <0 0xe6080000 0 0x1000>;
};
...

---
arch/arm/mach-shmobile/setup-rcar-gen2.c | 17 ++++++++++++++++-
1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/arch/arm/mach-shmobile/setup-rcar-gen2.c b/arch/arm/mach-shmobile/setup-rcar-gen2.c
index 35dda21..153e3f5 100644
--- a/arch/arm/mach-shmobile/setup-rcar-gen2.c
+++ b/arch/arm/mach-shmobile/setup-rcar-gen2.c
@@ -15,6 +15,7 @@
#include <linux/kernel.h>
#include <linux/memblock.h>
#include <linux/of.h>
+#include <linux/of_address.h>
#include <linux/of_fdt.h>
#include <linux/of_platform.h>
#include <asm/mach/arch.h>
@@ -61,6 +62,8 @@ static unsigned int __init get_extal_freq(void)

void __init rcar_gen2_timer_init(void)
{
+ struct device_node *np;
+ struct resource res;
void __iomem *base;
u32 freq;

@@ -72,6 +75,13 @@ void __init rcar_gen2_timer_init(void)
if (!psci_smp_available())
secure_cntvoff_init();

+ np = of_find_compatible_node(NULL, NULL, "arm,armv7-timer");
+ if (!np)
+ goto out;
+
+ if (of_address_to_resource(np, 0, &res))
+ goto out;
+
if (of_machine_is_compatible("renesas,r8a7745") ||
of_machine_is_compatible("renesas,r8a77470") ||
of_machine_is_compatible("renesas,r8a7792") ||
@@ -88,7 +98,9 @@ void __init rcar_gen2_timer_init(void)
}

/* Remap "armgcnt address map" space */
- base = ioremap(0xe6080000, PAGE_SIZE);
+ base = ioremap(res.start, resource_size(&res));
+ if (!base)
+ goto out;

/*
* Update the timer if it is either not running, or is not at the
@@ -109,6 +121,9 @@ void __init rcar_gen2_timer_init(void)

iounmap(base);

+out:
+ of_node_put(np);
+
of_clk_init(NULL);
timer_probe();
}
--
2.7.4
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