linux-kernel - [PATCH v7 02/12] irqchip: loongson-liointc: Workaround LPC IRQ Errata

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Date:   Wed, 25 Mar 2020 10:28:19 +0800
From:   Jiaxun Yang <jiaxun.yang@...goat.com>
To:     linux-mips@...r.kernel.org
Cc:     Jiaxun Yang <jiaxun.yang@...goat.com>,
        Huacai Chen <chenhc@...ote.com>, Marc Zyngier <maz@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Jonathan Corbet <corbet@....net>,
        Paul Cercueil <paul@...pouillou.net>,
        John Crispin <john@...ozen.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Jean Delvare <jdelvare@...e.com>,
        "David S. Miller" <davem@...emloft.net>,
        Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Andi Kleen <ak@...ux.intel.com>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Kees Cook <keescook@...omium.org>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        "H. Nikolaus Schaller" <hns@...delico.com>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Yinglu Yang <yangyinglu@...ngson.cn>,
        Tiezhu Yang <yangtiezhu@...ngson.cn>,
        Allison Randal <allison@...utok.net>,
        Paul Burton <paulburton@...nel.org>,
        Manuel Lauss <manuel.lauss@...il.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Serge Semin <fancer.lancer@...il.com>,
        Matt Redfearn <matt.redfearn@...s.com>,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-ide@...r.kernel.org
Subject: [PATCH v7 02/12] irqchip: loongson-liointc: Workaround LPC IRQ Errata

The 1.0 version of that controller has a bug that status bit
of LPC IRQ sometimes doesn't get set correctly.

So we can always blame LPC IRQ when spurious interrupt happens
at the parent interrupt line which LPC IRQ supposed to route
to.

Signed-off-by: Jiaxun Yang <jiaxun.yang@...goat.com>
Co-developed-by: Huacai Chen <chenhc@...ote.com>
Signed-off-by: Huacai Chen <chenhc@...ote.com>
Reviewed-by: Marc Zyngier <maz@...nel.org>
---
 drivers/irqchip/irq-loongson-liointc.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/irqchip/irq-loongson-liointc.c b/drivers/irqchip/irq-loongson-liointc.c
index 18de2c09ece4..7d2339e638db 100644
--- a/drivers/irqchip/irq-loongson-liointc.c
+++ b/drivers/irqchip/irq-loongson-liointc.c
@@ -32,6 +32,8 @@
 
 #define LIOINTC_SHIFT_INTx	4
 
+#define LIOINTC_ERRATA_IRQ	10
+
 struct liointc_handler_data {
 	struct liointc_priv	*priv;
 	u32			parent_int_map;
@@ -41,6 +43,7 @@ struct liointc_priv {
 	struct irq_chip_generic		*gc;
 	struct liointc_handler_data	handler[LIOINTC_NUM_PARENT];
 	u8				map_cache[LIOINTC_CHIP_IRQ];
+	bool				have_lpc_irq_errata;
 };
 
 static void liointc_chained_handle_irq(struct irq_desc *desc)
@@ -54,8 +57,15 @@ static void liointc_chained_handle_irq(struct irq_desc *desc)
 
 	pending = readl(gc->reg_base + LIOINTC_REG_INTC_STATUS);
 
-	if (!pending)
-		spurious_interrupt();
+	if (!pending) {
+		/* Always blame LPC IRQ if we have that bug */
+		if (handler->priv->have_lpc_irq_errata &&
+			(handler->parent_int_map & ~gc->mask_cache &
+			BIT(LIOINTC_ERRATA_IRQ)))
+			pending = BIT(LIOINTC_ERRATA_IRQ);
+		else
+			spurious_interrupt();
+	}
 
 	while (pending) {
 		int bit = __ffs(pending);
-- 
2.26.0.rc2