arm/acpi: Parse GTDT to initialize timer

Parse GTDT (Generic Timer Descriptor Table) to initialize timer. Using
the information presented by GTDT to initialize the arch timer (not
memory-mapped).

Signed-off-by: Parth Dixit <parth.dixit@linaro.org>
Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

xen/arch/arm/time.c

@@ -29,6 +29,7 @@
 #include <xen/time.h>
 #include <xen/sched.h>
 #include <xen/event.h>
+#include <xen/acpi.h>
 #include <asm/system.h>
 #include <asm/time.h>
 #include <asm/gic.h>
@@ -65,8 +66,51 @@ unsigned int timer_get_irq(enum timer_ppi ppi)
 
 static __initdata struct dt_device_node *timer;
 
+#ifdef CONFIG_ACPI
+static u32 __init acpi_get_timer_irq_type(u32 flags)
+{
+    return (flags & ACPI_GTDT_INTERRUPT_MODE) ? IRQ_TYPE_EDGE_BOTH
+                                              : IRQ_TYPE_LEVEL_MASK;
+}
+
+/* Initialize per-processor generic timer */
+static int __init arch_timer_acpi_init(struct acpi_table_header *header)
+{
+    u32 irq_type;
+    struct acpi_table_gtdt *gtdt;
+
+    gtdt = container_of(header, struct acpi_table_gtdt, header);
+
+    /* Initialize all the generic timer IRQ variable from GTDT table */
+    irq_type = acpi_get_timer_irq_type(gtdt->non_secure_el1_flags);
+    irq_set_type(gtdt->non_secure_el1_interrupt, irq_type);
+    timer_irq[TIMER_PHYS_NONSECURE_PPI] = gtdt->non_secure_el1_interrupt;
+
+    irq_type = acpi_get_timer_irq_type(gtdt->secure_el1_flags);
+    irq_set_type(gtdt->secure_el1_interrupt, irq_type);
+    timer_irq[TIMER_PHYS_SECURE_PPI] = gtdt->secure_el1_interrupt;
+
+    irq_type = acpi_get_timer_irq_type(gtdt->virtual_timer_flags);
+    irq_set_type(gtdt->virtual_timer_interrupt, irq_type);
+    timer_irq[TIMER_VIRT_PPI] = gtdt->virtual_timer_interrupt;
+
+    irq_type = acpi_get_timer_irq_type(gtdt->non_secure_el2_flags);
+    irq_set_type(gtdt->non_secure_el2_interrupt, irq_type);
+    timer_irq[TIMER_HYP_PPI] = gtdt->non_secure_el2_interrupt;
+
+    return 0;
+}
+
+static void __init preinit_acpi_xen_time(void)
+{
+    acpi_table_parse(ACPI_SIG_GTDT, arch_timer_acpi_init);
+}
+#else
+static void __init preinit_acpi_xen_time(void) { }
+#endif
+
 /* Set up the timer on the boot CPU (early init function) */
-void __init preinit_xen_time(void)
+static void __init preinit_dt_xen_time(void)
 {
     static const struct dt_device_match timer_ids[] __initconst =
     {
@@ -75,6 +119,7 @@ void __init preinit_xen_time(void)
     };
     int res;
     u32 rate;
+    unsigned int i;
 
     timer = dt_find_matching_node(NULL, timer_ids);
     if ( !timer )
@@ -82,27 +127,12 @@ void __init preinit_xen_time(void)
 
     dt_device_set_used_by(timer, DOMID_XEN);
 
-    res = platform_init_time();
-    if ( res )
-        panic("Timer: Cannot initialize platform timer");
-
     res = dt_property_read_u32(timer, "clock-frequency", &rate);
     if ( res )
     {
         cpu_khz = rate / 1000;
         timer_dt_clock_frequency = rate;
     }
-    else
-        cpu_khz = READ_SYSREG32(CNTFRQ_EL0) / 1000;
-
-    boot_count = READ_SYSREG64(CNTPCT_EL0);
-}
-
-/* Set up the timer on the boot CPU (late init function) */
-int __init init_xen_time(void)
-{
-    int res;
-    unsigned int i;
 
     /* Retrieve all IRQs for the timer */
     for ( i = TIMER_PHYS_SECURE_PPI; i < MAX_TIMER_PPI; i++ )
@@ -113,7 +143,31 @@ int __init init_xen_time(void)
             panic("Timer: Unable to retrieve IRQ %u from the device tree", i);
         timer_irq[i] = res;
     }
+}
 
+void __init preinit_xen_time(void)
+{
+    int res;
+
+    /* Initialize all the generic timers presented in GTDT */
+    if ( acpi_disabled )
+        preinit_dt_xen_time();
+    else
+        preinit_acpi_xen_time();
+
+    if ( !cpu_khz )
+        cpu_khz = READ_SYSREG32(CNTFRQ_EL0) / 1000;
+
+    res = platform_init_time();
+    if ( res )
+        panic("Timer: Cannot initialize platform timer");
+
+    boot_count = READ_SYSREG64(CNTPCT_EL0);
+}
+
+/* Set up the timer on the boot CPU (late init function) */
+int __init init_xen_time(void)
+{
     /* Check that this CPU supports the Generic Timer interface */
     if ( !cpu_has_gentimer )
         panic("CPU does not support the Generic Timer v1 interface");