irqchip/gic-v3-its: Kill its->device_ids and use TYPER copy instead

Now that we have a copy of TYPER in the ITS structure, rely on this
to provide the same service as its->device_ids, which gets axed.
Errata workarounds are now updating the cached fields instead of
requiring a separate field in the ITS structure.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Zenghui Yu <yuzenghui@huawei.com>
Link: https://lore.kernel.org/r/20191027144234.8395-7-maz@kernel.org
Link: https://lore.kernel.org/r/20191108165805.3071-7-maz@kernel.org

drivers/irqchip/irq-gic-v3-its.c

@@ -109,7 +109,6 @@ struct its_node {
 	struct list_head	its_device_list;
 	u64			flags;
 	unsigned long		list_nr;
-	u32			device_ids;
 	int			numa_node;
 	unsigned int		msi_domain_flags;
 	u32			pre_its_base; /* for Socionext Synquacer */
@@ -117,6 +116,7 @@ struct its_node {
 };
 
 #define is_v4(its)		(!!((its)->typer & GITS_TYPER_VLPIS))
+#define device_ids(its)		(FIELD_GET(GITS_TYPER_DEVBITS, (its)->typer) + 1)
 
 #define ITS_ITT_ALIGN		SZ_256
 
@@ -1956,9 +1956,9 @@ static bool its_parse_indirect_baser(struct its_node *its,
 	if (new_order >= MAX_ORDER) {
 		new_order = MAX_ORDER - 1;
 		ids = ilog2(PAGE_ORDER_TO_SIZE(new_order) / (int)esz);
-		pr_warn("ITS@%pa: %s Table too large, reduce ids %u->%u\n",
+		pr_warn("ITS@%pa: %s Table too large, reduce ids %llu->%u\n",
 			&its->phys_base, its_base_type_string[type],
-			its->device_ids, ids);
+			device_ids(its), ids);
 	}
 
 	*order = new_order;
@@ -2004,7 +2004,7 @@ static int its_alloc_tables(struct its_node *its)
 		case GITS_BASER_TYPE_DEVICE:
 			indirect = its_parse_indirect_baser(its, baser,
 							    psz, &order,
-							    its->device_ids);
+							    device_ids(its));
 			break;
 
 		case GITS_BASER_TYPE_VCPU:
@@ -2395,7 +2395,7 @@ static bool its_alloc_device_table(struct its_node *its, u32 dev_id)
 
 	/* Don't allow device id that exceeds ITS hardware limit */
 	if (!baser)
-		return (ilog2(dev_id) < its->device_ids);
+		return (ilog2(dev_id) < device_ids(its));
 
 	return its_alloc_table_entry(its, baser, dev_id);
 }
@@ -3247,8 +3247,9 @@ static bool __maybe_unused its_enable_quirk_cavium_22375(void *data)
 {
 	struct its_node *its = data;
 
-	/* erratum 22375: only alloc 8MB table size */
-	its->device_ids = 0x14;		/* 20 bits, 8MB */
+	/* erratum 22375: only alloc 8MB table size (20 bits) */
+	its->typer &= ~GITS_TYPER_DEVBITS;
+	its->typer |= FIELD_PREP(GITS_TYPER_DEVBITS, 20 - 1);
 	its->flags |= ITS_FLAGS_WORKAROUND_CAVIUM_22375;
 
 	return true;
@@ -3303,8 +3304,10 @@ static bool __maybe_unused its_enable_quirk_socionext_synquacer(void *data)
 		its->get_msi_base = its_irq_get_msi_base_pre_its;
 
 		ids = ilog2(pre_its_window[1]) - 2;
-		if (its->device_ids > ids)
-			its->device_ids = ids;
+		if (device_ids(its) > ids) {
+			its->typer &= ~GITS_TYPER_DEVBITS;
+			its->typer |= FIELD_PREP(GITS_TYPER_DEVBITS, ids - 1);
+		}
 
 		/* the pre-ITS breaks isolation, so disable MSI remapping */
 		its->msi_domain_flags &= ~IRQ_DOMAIN_FLAG_MSI_REMAP;
@@ -3537,7 +3540,7 @@ static int its_init_vpe_domain(void)
 	}
 
 	/* Use the last possible DevID */
-	devid = GENMASK(its->device_ids - 1, 0);
+	devid = GENMASK(device_ids(its) - 1, 0);
 	vpe_proxy.dev = its_create_device(its, devid, entries, false);
 	if (!vpe_proxy.dev) {
 		kfree(vpe_proxy.vpes);
@@ -3638,7 +3641,6 @@ static int __init its_probe_one(struct resource *res,
 	its->typer = typer;
 	its->base = its_base;
 	its->phys_base = res->start;
-	its->device_ids = GITS_TYPER_DEVBITS(typer);
 	if (is_v4(its)) {
 		if (!(typer & GITS_TYPER_VMOVP)) {
 			err = its_compute_its_list_map(res, its_base);

include/linux/irqchip/arm-gic-v3.h

@@ -337,7 +337,7 @@
 #define GITS_TYPER_ITT_ENTRY_SIZE	GENMASK_ULL(7, 4)
 #define GITS_TYPER_IDBITS_SHIFT		8
 #define GITS_TYPER_DEVBITS_SHIFT	13
-#define GITS_TYPER_DEVBITS(r)		((((r) >> GITS_TYPER_DEVBITS_SHIFT) & 0x1f) + 1)
+#define GITS_TYPER_DEVBITS		GENMASK_ULL(17, 13)
 #define GITS_TYPER_PTA			(1UL << 19)
 #define GITS_TYPER_HCC_SHIFT		24
 #define GITS_TYPER_HCC(r)		(((r) >> GITS_TYPER_HCC_SHIFT) & 0xff)