refactor(gicv3): add helper function to get the limit of ESPI INTID

Add helper function gicv3_get_espi_limit() to get the value of
(maximum extended SPI INTID + 1), so that some duplicated code can be
removed later.
Signed-off-by: Heyi Guo <guoheyi@linux.alibaba.com>
Change-Id: I0355ca2647f872e8189add259f6c47d415494cce

drivers/arm/gic/v3/gicv3_helpers.c

@@ -110,6 +110,28 @@ unsigned int gicv3_get_spi_limit(uintptr_t gicd_base)
 	return spi_limit;
 }
 
+#if GIC_EXT_INTID
+/*******************************************************************************
+ * Helper function to get the maximum ESPI INTID + 1.
+ ******************************************************************************/
+unsigned int gicv3_get_espi_limit(uintptr_t gicd_base)
+{
+	unsigned int typer_reg = gicd_read_typer(gicd_base);
+
+	/* Check if extended SPI range is implemented */
+	if ((typer_reg & TYPER_ESPI) != 0U) {
+		/*
+		 * (maximum ESPI INTID + 1) is equal to
+		 * 32 * (GICD_TYPER.ESPI_range + 1) + 4096
+		 */
+		return ((((typer_reg >> TYPER_ESPI_RANGE_SHIFT) &
+			TYPER_ESPI_RANGE_MASK) + 1U) << 5) + MIN_ESPI_ID;
+	}
+
+	return 0U;
+}
+#endif /* GIC_EXT_INTID */
+
 /*******************************************************************************
  * Helper function to configure the default attributes of (E)SPIs.
  ******************************************************************************/

drivers/arm/gic/v3/gicv3_private.h

@@ -234,6 +234,7 @@ void gicr_set_icfgr(uintptr_t base, unsigned int id, unsigned int cfg);
  * Private GICv3 helper function prototypes
  ******************************************************************************/
 unsigned int gicv3_get_spi_limit(uintptr_t gicd_base);
+unsigned int gicv3_get_espi_limit(uintptr_t gicd_base);
 void gicv3_spis_config_defaults(uintptr_t gicd_base);
 void gicv3_ppi_sgi_config_defaults(uintptr_t gicr_base);
 unsigned int gicv3_secure_ppi_sgi_config_props(uintptr_t gicr_base,