irqchip/loongson-liointc: Fix misuse of gc->mask_cache

In gc->mask_cache bits, 1 means enabled and 0 means disabled, but in the
loongson-liointc driver mask_cache is misused by reverting its meaning.
This patch fix the bug and update the comments as well.

Fixes: dbb1522 ("irqchip: Add driver for Loongson I/O Local Interrupt Controller")
Signed-off-by: Huacai Chen <chenhc@lemote.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/1596099090-23516-4-git-send-email-chenhc@lemote.com

Author: chenhuacai

drivers/irqchip/irq-loongson-liointc.c

@@ -60,7 +60,7 @@ static void liointc_chained_handle_irq(struct irq_desc *desc)
 	if (!pending) {
 		/* Always blame LPC IRQ if we have that bug */
 		if (handler->priv->has_lpc_irq_errata &&
-			(handler->parent_int_map & ~gc->mask_cache &
+			(handler->parent_int_map & gc->mask_cache &
 			BIT(LIOINTC_ERRATA_IRQ)))
 			pending = BIT(LIOINTC_ERRATA_IRQ);
 		else
@@ -132,11 +132,11 @@ static void liointc_resume(struct irq_chip_generic *gc)
 	irq_gc_lock_irqsave(gc, flags);
 	/* Disable all at first */
 	writel(0xffffffff, gc->reg_base + LIOINTC_REG_INTC_DISABLE);
-	/* Revert map cache */
+	/* Restore map cache */
 	for (i = 0; i < LIOINTC_CHIP_IRQ; i++)
 		writeb(priv->map_cache[i], gc->reg_base + i);
-	/* Revert mask cache */
-	writel(~gc->mask_cache, gc->reg_base + LIOINTC_REG_INTC_ENABLE);
+	/* Restore mask cache */
+	writel(gc->mask_cache, gc->reg_base + LIOINTC_REG_INTC_ENABLE);
 	irq_gc_unlock_irqrestore(gc, flags);
 }
 
@@ -244,7 +244,7 @@ int __init liointc_of_init(struct device_node *node,
 	ct->chip.irq_mask_ack = irq_gc_mask_disable_reg;
 	ct->chip.irq_set_type = liointc_set_type;
 
-	gc->mask_cache = 0xffffffff;
+	gc->mask_cache = 0;
 	priv->gc = gc;
 
 	for (i = 0; i < LIOINTC_NUM_PARENT; i++) {