Revert "MIPS: perf: ath79: Fix perfcount IRQ assignment"

This reverts commit ca864881 which is
commit a1e8783d upstream.

Petr writes:
	Karl has reported to me today, that he's experiencing weird
	reboot hang on his devices with 4.9.180 kernel and that he has
	bisected it down to my backported patch.

	I would like to kindly ask you for removal of this patch.  This
	patch should be reverted from all stable kernels up to 5.1,
	because perf counters were not broken on those kernels, and this
	patch won't work on the ath79 legacy IRQ code anyway, it needs
	new irqchip driver which was enabled on ath79 with commit
	51fa4f89 ("MIPS: ath79: drop legacy IRQ code").
Reported-by: Petr Štetiar <ynezz@true.cz>
Cc: Kevin 'ldir' Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>
Cc: John Crispin <john@phrozen.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/mips/ath79/setup.c

@@ -211,6 +211,12 @@ const char *get_system_type(void)
 	return ath79_sys_type;
 }
 
+int get_c0_perfcount_int(void)
+{
+	return ATH79_MISC_IRQ(5);
+}
+EXPORT_SYMBOL_GPL(get_c0_perfcount_int);
+
 unsigned int get_c0_compare_int(void)
 {
 	return CP0_LEGACY_COMPARE_IRQ;

drivers/irqchip/irq-ath79-misc.c

@@ -22,15 +22,6 @@
 #define AR71XX_RESET_REG_MISC_INT_ENABLE	4
 
 #define ATH79_MISC_IRQ_COUNT			32
-#define ATH79_MISC_PERF_IRQ			5
-
-static int ath79_perfcount_irq;
-
-int get_c0_perfcount_int(void)
-{
-	return ath79_perfcount_irq;
-}
-EXPORT_SYMBOL_GPL(get_c0_perfcount_int);
 
 static void ath79_misc_irq_handler(struct irq_desc *desc)
 {
@@ -122,8 +113,6 @@ static void __init ath79_misc_intc_domain_init(
 {
 	void __iomem *base = domain->host_data;
 
-	ath79_perfcount_irq = irq_create_mapping(domain, ATH79_MISC_PERF_IRQ);
-
 	/* Disable and clear all interrupts */
 	__raw_writel(0, base + AR71XX_RESET_REG_MISC_INT_ENABLE);
 	__raw_writel(0, base + AR71XX_RESET_REG_MISC_INT_STATUS);