irqchip/irq-bcm7038-l1: Support brcm,int-fwd-mask

On some specific chips like 7211 we need to leave some interrupts
untouched/forwarded to the VPU which is another agent in the system
making use of that interrupt controller hardware (goes to both ARM GIC
and VPU L1 interrupt controller). Make that possible by using the
existing brcm,int-fwd-mask property and take necessary actions to avoid
masking that interrupt as well as not allowing Linux to map them.

Signed-off-by: Florian Fainelli <[e-mail]>
Signed-off-by: Marc Zyngier <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

drivers/irqchip/irq-bcm7038-l1.c

···
 	struct list_head	list;
 	u32			wake_mask[MAX_WORDS];
 #endif
+	u32			irq_fwd_mask[MAX_WORDS];
 	u8			affinity[MAX_WORDS * IRQS_PER_WORD];
 };
 
···
 	resource_size_t sz;
 	struct bcm7038_l1_cpu *cpu;
 	unsigned int i, n_words, parent_irq;
+	int ret;
 
 	if (of_address_to_resource(dn, idx, &res))
 		return -EINVAL;
···
 	else if (intc->n_words != n_words)
 		return -EINVAL;
 
+	ret = of_property_read_u32_array(dn , "brcm,int-fwd-mask",
+					 intc->irq_fwd_mask, n_words);
+	if (ret != 0 && ret != -EINVAL) {
+		/* property exists but has the wrong number of words */
+		pr_err("invalid brcm,int-fwd-mask property\n");
+		return -EINVAL;
+	}
+
 	cpu = intc->cpus[idx] = kzalloc(sizeof(*cpu) + n_words * sizeof(u32),
 					GFP_KERNEL);
 	if (!cpu)
···
 		return -ENOMEM;
 
 	for (i = 0; i < n_words; i++) {
-		l1_writel(0xffffffff, cpu->map_base + reg_mask_set(intc, i));
-		cpu->mask_cache[i] = 0xffffffff;
+		l1_writel(~intc->irq_fwd_mask[i],
+			  cpu->map_base + reg_mask_set(intc, i));
+		l1_writel(intc->irq_fwd_mask[i],
+			  cpu->map_base + reg_mask_clr(intc, i));
+		cpu->mask_cache[i] = ~intc->irq_fwd_mask[i];
 	}
 
 	parent_irq = irq_of_parse_and_map(dn, idx);
···
 {
 	struct bcm7038_l1_chip *intc;
 	int boot_cpu, word;
+	u32 val;
 
 	/* Wakeup interrupt should only come from the boot cpu */
 	boot_cpu = cpu_logical_map(0);
 
 	list_for_each_entry(intc, &bcm7038_l1_intcs_list, list) {
 		for (word = 0; word < intc->n_words; word++) {
-			l1_writel(~intc->wake_mask[word],
+			val = intc->wake_mask[word] | intc->irq_fwd_mask[word];
+			l1_writel(~val,
 				intc->cpus[boot_cpu]->map_base + reg_mask_set(intc, word));
-			l1_writel(intc->wake_mask[word],
+			l1_writel(val,
 				intc->cpus[boot_cpu]->map_base + reg_mask_clr(intc, word));
 		}
 	}
···
 static int bcm7038_l1_map(struct irq_domain *d, unsigned int virq,
 			  irq_hw_number_t hw_irq)
 {
+	struct bcm7038_l1_chip *intc = d->host_data;
+	u32 mask = BIT(hw_irq % IRQS_PER_WORD);
+	u32 word = hw_irq / IRQS_PER_WORD;
+
+	if (intc->irq_fwd_mask[word] & mask)
+		return -EPERM;
+
 	irq_set_chip_and_handler(virq, &bcm7038_l1_irq_chip, handle_level_irq);
 	irq_set_chip_data(virq, d->host_data);
 	irqd_set_single_target(irq_desc_get_irq_data(irq_to_desc(virq)));