[Xen-devel] [ARM:PATCH v3 1/1] Pass the timer clock-frequency to DOM0 xen/arm: Pass the timer "clock-frequency" to DOM0 in make_timer_node()

[Suriyan Ramasami <suriyan.r@xxxxxxxxx>]

    If the DT representing the ARM generic timer mentions a clock-frequency,
    propragate it to the DT that is built for DOM0.

    This is necessary as a workaround for boards (Odroid-XU) where CNTFRQ is
    not set or returns a wrong value.

    Ideally CNTFRQ should be set by the boot loader. The bootloader should
    respect the ARM ARM (see B.8.1.1):
    "The CNTFRQ register is UNKNOWN at reset, and therefore the counter
    frequency must written to CNTFRQ as part of the system boot process."

    For the Odroid-XU the SPL BL2 code is entered in NS HYP mode which
    prevents the execution of the mcr call to set CNTFRQ.

Signed-off-by: Suriyan Ramasami <suriyan.r@xxxxxxxxx>

---
Changed since v2:
    * Gather all changes in one place.
    * Added additional comments

Changed since v1:
    * Fix typo for quotes around clock-frequency.
---
 xen/arch/arm/domain_build.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index 502db84..a86d756 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -622,6 +622,8 @@ static int make_timer_node(const struct domain *d, void 
*fdt,
     int res;
     const struct dt_irq *irq;
     gic_interrupt_t intrs[3];
+    u32 clock_frequency;
+    bool_t clock_valid;
 
     DPRINT("Create timer node\n");
 
@@ -663,6 +665,15 @@ static int make_timer_node(const struct domain *d, void 
*fdt,
     if ( res )
         return res;
 
+    clock_valid = dt_property_read_u32(dev, "clock-frequency",
+                                       &clock_frequency);
+    if (clock_valid)
+    {
+        res = fdt_property_cell(fdt, "clock-frequency", clock_frequency);
+        if ( res )
+            return res;
+    }
+
     res = fdt_end_node(fdt);
 
     return res;
-- 
1.8.3.2


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