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

Add helper function gicv3_get_spi_limit() to get the value of (maximum
SPI INTID + 1), so that some duplicated code can be removed later.
Signed-off-by: Heyi Guo <guoheyi@linux.alibaba.com>
Change-Id: I160c8a88fbb71d22790b8999a84afbfba766f5e7

drivers/arm/gic/v3/gicv3_helpers.c

@@ -91,6 +91,25 @@ void gicv3_rdistif_base_addrs_probe(uintptr_t *rdistif_base_addrs,
 	} while ((typer_val & TYPER_LAST_BIT) == 0U);
 }
 
+/*******************************************************************************
+ * Helper function to get the maximum SPI INTID + 1.
+ ******************************************************************************/
+unsigned int gicv3_get_spi_limit(uintptr_t gicd_base)
+{
+	unsigned int spi_limit;
+	unsigned int typer_reg = gicd_read_typer(gicd_base);
+
+	/* (maximum SPI INTID + 1) is equal to 32 * (GICD_TYPER.ITLinesNumber+1) */
+	spi_limit = ((typer_reg & TYPER_IT_LINES_NO_MASK) + 1U) << 5;
+
+	/* Filter out special INTIDs 1020-1023 */
+	if (spi_limit > (MAX_SPI_ID + 1U)) {
+		return MAX_SPI_ID + 1U;
+	}
+
+	return spi_limit;
+}
+
 /*******************************************************************************
  * Helper function to configure the default attributes of (E)SPIs.
  ******************************************************************************/

drivers/arm/gic/v3/gicv3_private.h

@@ -233,6 +233,7 @@ 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);
 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,