linux-kernel - [PATCH v3 2/4] clocksource/drivers/exynos

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20220407074432.424578-3-vincent.whitchurch@axis.com>
Date:   Thu, 7 Apr 2022 09:44:30 +0200
From:   Vincent Whitchurch <vincent.whitchurch@...s.com>
To:     <krzk@...nel.org>, <tglx@...utronix.de>,
        <daniel.lezcano@...aro.org>
CC:     <kernel@...s.com>,
        Vincent Whitchurch <vincent.whitchurch@...s.com>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-samsung-soc@...r.kernel.org>, <alim.akhtar@...sung.com>,
        <devicetree@...r.kernel.org>, <robh+dt@...nel.org>
Subject: [PATCH v3 2/4] clocksource/drivers/exynos_mct: Support frc-shared property

When the FRC is shared with another main processor, the other processor
is assumed to have started it and this processor should not write to the
global registers.

Signed-off-by: Vincent Whitchurch <vincent.whitchurch@...s.com>
---

Notes:
    v3:
    - Split FRC sharing handling from local timer indices handling
    - Remove addition of global variable.

 drivers/clocksource/exynos_mct.c | 21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/drivers/clocksource/exynos_mct.c b/drivers/clocksource/exynos_mct.c
index f29c812b70c9..12023831dedf 100644
--- a/drivers/clocksource/exynos_mct.c
+++ b/drivers/clocksource/exynos_mct.c
@@ -233,9 +233,16 @@ static cycles_t exynos4_read_current_timer(void)
 }
 #endif
 
-static int __init exynos4_clocksource_init(void)
+static int __init exynos4_clocksource_init(bool frc_shared)
 {
-	exynos4_mct_frc_start();
+	/*
+	 * When the frc is shared, the main processer should have already
+	 * turned it on and we shouldn't be writing to TCON.
+	 */
+	if (frc_shared)
+		mct_frc.resume = NULL;
+	else
+		exynos4_mct_frc_start();
 
 #if defined(CONFIG_ARM)
 	exynos4_delay_timer.read_current_timer = &exynos4_read_current_timer;
@@ -605,6 +612,7 @@ static int __init exynos4_timer_interrupts(struct device_node *np,
 
 static int __init mct_init_dt(struct device_node *np, unsigned int int_type)
 {
+	bool frc_shared = of_property_read_bool(np, "samsung,frc-shared");
 	int ret;
 
 	ret = exynos4_timer_resources(np);
@@ -615,10 +623,17 @@ static int __init mct_init_dt(struct device_node *np, unsigned int int_type)
 	if (ret)
 		return ret;
 
-	ret = exynos4_clocksource_init();
+	ret = exynos4_clocksource_init(frc_shared);
 	if (ret)
 		return ret;
 
+	/*
+	 * When the FRC is shared with a main processor, this secondary
+	 * processor cannot use the global comparator.
+	 */
+	if (frc_shared)
+		return ret;
+
 	return exynos4_clockevent_init();
 }
 
-- 
2.34.1