plat/xen: Introduce an implementation of uk_intctlr_plat_probe

uk_intctlr_plat_probe is platform specific initialization for GIC
drivers. It maps destributor/redistributor address to the page table
so system can access registers and returns mapped addresses to
GIC driver.

Signed-off-by: Oleksii Moisieiev <oleksii_moisieiev@epam.com>
Reviewed-by: Michalis Pappas <michalis@unikraft.io>
Reviewed-by: Andrei Stan <andreistan2003@gmail.com>
Approved-by: Michalis Pappas <michalis@unikraft.io>
GitHub-Closes: #726

plat/xen/arm/setup64.c

@@ -34,6 +34,7 @@
 #include <uk/plat/memory.h>
 #include <xen/memory.h>
 #include <uk/intctlr.h>
+#include <uk/intctlr/gic.h>
 #include <xen/hvm/params.h>
 #include <libfdt.h>
 #include <xen-arm/setup.h>
@@ -204,6 +205,28 @@ static inline void _get_cmdline(struct ukplat_bootinfo *bi)
 	bi->cmdline_len = cmdline_len;
 }
 
+int uk_intctlr_plat_probe(void *in, void *out)
+{
+	struct uk_intctlr_plat_data *dout = (struct uk_intctlr_plat_data *)out;
+	struct uk_intctlr_plat_data *din = (struct uk_intctlr_plat_data *)in;
+
+	if (!in || !out)
+		return -EINVAL;
+
+#if defined(__arm__)
+	dout->dist_addr = to_virt((long)fdt64_ld(din->dist_addr));
+	dout->rdist_addr = to_virt((long)fdt64_ld(din->rdist_addr));
+#else
+	set_pgt_entry(&fixmap_pgtable[l2_pgt_idx(FIX_GIC_START)],
+		      ((din->dist_addr & L2_MASK) | BLOCK_DEV_ATTR | L2_BLOCK));
+	dout->dist_addr = (FIX_GIC_START + (din->dist_addr & L2_OFFSET));
+	dout->rdist_addr = (FIX_GIC_START + (din->rdist_addr & L2_OFFSET));
+#endif
+	/* Setting memory barrier to get access to mapped pages */
+	wmb();
+	return 0;
+}
+
 static int _init_mem(struct ukplat_bootinfo *const bi, paddr_t physical_offset)
 {
 	int rc;