riscv: define function set_gd()

Function set_gd() is needed in the UEFI sub-system if the global data
pointer is stored in a register.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/arch/riscv/include/asm/global_data.h b/arch/riscv/include/asm/global_data.h
index 2eb1481..b711fcc 100644
--- a/arch/riscv/include/asm/global_data.h
+++ b/arch/riscv/include/asm/global_data.h
@@ -39,4 +39,13 @@
 
 #define DECLARE_GLOBAL_DATA_PTR register gd_t *gd asm ("gp")
 
+static inline void set_gd(volatile gd_t *gd_ptr)
+{
+#ifdef CONFIG_64BIT
+	asm volatile("ld gp, %0\n" : : "m"(gd_ptr));
+#else
+	asm volatile("lw gp, %0\n" : : "m"(gd_ptr));
+#endif
+}
+
 #endif /* __ASM_GBL_DATA_H */