linux-kernel - [PATCH v2] of/irq: Add a quirk for controllers with their own definition of interrupt-map

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Message-Id: <20211201114102.13446-1-maz@kernel.org>
Date:   Wed,  1 Dec 2021 11:41:02 +0000
From:   Marc Zyngier <maz@...nel.org>
To:     linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Cc:     kernel-team@...roid.com, Rob Herring <robh@...nel.org>,
        John Crispin <john@...ozen.org>, Biwen Li <biwen.li@....com>,
        Chris Brandt <chris.brandt@...esas.com>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Sander Vanheule <sander@...nheule.net>
Subject: [PATCH v2] of/irq: Add a quirk for controllers with their own definition of interrupt-map

Since 041284181226 ("of/irq: Allow matching of an interrupt-map local
to an interrupt controller"), a handful of interrupt controllers have
stopped working correctly. This is due to the DT exposing a non-sensical
interrupt-map property, and their drivers relying on the kernel ignoring
this property.

Since we cannot realistically fix this terrible behaviour, add a quirk
for the limited set of devices that have implemented this monster,
and document that this is a pretty bad practice.

Cc: Rob Herring <robh@...nel.org>
Cc: John Crispin <john@...ozen.org>
Cc: Biwen Li <biwen.li@....com>
Cc: Chris Brandt <chris.brandt@...esas.com>
Cc: Geert Uytterhoeven <geert+renesas@...der.be>
Cc: Sander Vanheule <sander@...nheule.net>
Signed-off-by: Marc Zyngier <maz@...nel.org>
---

Notes:
    v2: Switched over to of_device_compatible_match() as per Rob's
        request.

 drivers/of/irq.c | 28 ++++++++++++++++++++++++++--
 1 file changed, 26 insertions(+), 2 deletions(-)

diff --git a/drivers/of/irq.c b/drivers/of/irq.c
index b10f015b2e37..65a325aad984 100644
--- a/drivers/of/irq.c
+++ b/drivers/of/irq.c
@@ -76,6 +76,26 @@ struct device_node *of_irq_find_parent(struct device_node *child)
 }
 EXPORT_SYMBOL_GPL(of_irq_find_parent);
 
+/*
+ * These interrupt controllers abuse interrupt-map for unspeakable
+ * reasons and rely on the core code to *ignore* it (the drivers do
+ * their own parsing of the property).
+ *
+ * If you think of adding to the list for something *new*, think
+ * again. There is a high chance that you will be sent back to the
+ * drawing board.
+ */
+static const char * const of_irq_imap_abusers[] = {
+	"CBEA,platform-spider-pic",
+	"sti,platform-spider-pic",
+	"realtek,rtl-intc",
+	"fsl,ls1021a-extirq",
+	"fsl,ls1043a-extirq",
+	"fsl,ls1088a-extirq",
+	"renesas,rza1-irqc",
+	NULL,
+};
+
 /**
  * of_irq_parse_raw - Low level interrupt tree parsing
  * @addr:	address specifier (start of "reg" property of the device) in be32 format
@@ -159,12 +179,16 @@ int of_irq_parse_raw(const __be32 *addr, struct of_phandle_args *out_irq)
 		/*
 		 * Now check if cursor is an interrupt-controller and
 		 * if it is then we are done, unless there is an
-		 * interrupt-map which takes precedence.
+		 * interrupt-map which takes precedence if we're not
+		 * in presence of once of these broken platform that
+		 * want to parse interrupt-map themselves for $reason.
 		 */
 		bool intc = of_property_read_bool(ipar, "interrupt-controller");
+		bool imap_abuse;
 
 		imap = of_get_property(ipar, "interrupt-map", &imaplen);
-		if (imap == NULL && intc) {
+		imap_abuse = imap && of_device_compatible_match(ipar, of_irq_imap_abusers);
+		if (intc && (imap == NULL || imap_abuse)) {
 			pr_debug(" -> got it !\n");
 			return 0;
 		}
-- 
2.30.2