linux-kernel - [PATCH] clocksource/drivers/sp804: avoid error on multiple instances

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Message-Id: <20220427142759.4138694-1-andre.przywara@arm.com>
Date:   Wed, 27 Apr 2022 15:27:59 +0100
From:   Andre Przywara <andre.przywara@....com>
To:     Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Russell King <linux@...linux.org.uk>,
        Kefeng Wang <wangkefeng.wang@...wei.com>,
        Zhen Lei <thunder.leizhen@...wei.com>
Subject: [PATCH] clocksource/drivers/sp804: avoid error on multiple instances

When a machine sports more than one SP804 timer instance, we only bring
up the first one, since multiple timers of the same kind are not useful
to Linux. As this is intentional behaviour, we should not return an
error message, as we do today:
===============
[    0.000800] Failed to initialize '/bus@...0000/motherboard-bus@...0000/iofpga-bus@...000000/timer@...000': -22
===============

Replace the -EINVAL return with an informative message and return 0
instead.

Also we do not reach the init function anymore if the DT node is
disabled (as this is now handled by OF_DECLARE), so remove the explicit
check for that case.

This fixes a long standing bogus error when booting ARM's fastmodels.

Signed-off-by: Andre Przywara <andre.przywara@....com>
---
 drivers/clocksource/timer-sp804.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/clocksource/timer-sp804.c b/drivers/clocksource/timer-sp804.c
index 401d592e85f5a..30cbc580e0448 100644
--- a/drivers/clocksource/timer-sp804.c
+++ b/drivers/clocksource/timer-sp804.c
@@ -259,6 +259,12 @@ static int __init sp804_of_init(struct device_node *np, struct sp804_timer *time
 	struct clk *clk1, *clk2;
 	const char *name = of_get_property(np, "compatible", NULL);
 
+	if (initialized) {
+		pr_info("%s: only instantiating one timer\n",
+			of_node_full_name(np));
+		return 0;
+	}
+
 	base = of_iomap(np, 0);
 	if (!base)
 		return -ENXIO;
@@ -270,11 +276,6 @@ static int __init sp804_of_init(struct device_node *np, struct sp804_timer *time
 	writel(0, timer1_base + timer->ctrl);
 	writel(0, timer2_base + timer->ctrl);
 
-	if (initialized || !of_device_is_available(np)) {
-		ret = -EINVAL;
-		goto err;
-	}
-
 	clk1 = of_clk_get(np, 0);
 	if (IS_ERR(clk1))
 		clk1 = NULL;
-- 
2.25.1