linux-kernel - [RFC PATCH 1/4] power: reset: reboot-mode: Allow magic to be 0

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Message-ID: <20230724223057.1208122-2-quic_eberman@quicinc.com>
Date:   Mon, 24 Jul 2023 15:30:51 -0700
From:   Elliot Berman <quic_eberman@...cinc.com>
To:     Mark Rutland <mark.rutland@....com>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Sebastian Reichel <sre@...nel.org>
CC:     Elliot Berman <quic_eberman@...cinc.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        "Rob Herring" <robh+dt@...nel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <linux-pm@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-arm-msm@...r.kernel.org>, <kernel@...cinc.com>,
        Satya Durga Srinivasu Prabhala <quic_satyap@...cinc.com>,
        Melody Olvera <quic_molvera@...cinc.com>,
        "Prasad Sodagudi" <quic_psodagud@...cinc.com>
Subject: [RFC PATCH 1/4] power: reset: reboot-mode: Allow magic to be 0

Allow magic from the reboot-mode driver to be defined, but 0. This is
useful when the register/command to trigger reboot needs 0 to be
written. This is the case when the "default" reboot mode is to enter a
crash dump collection mode (e.g. when triggered by a watchdog) and Linux
doing a normal reboot requires the setting to be explicitly reset to
zero.

Signed-off-by: Elliot Berman <quic_eberman@...cinc.com>
---
 drivers/power/reset/reboot-mode.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/drivers/power/reset/reboot-mode.c b/drivers/power/reset/reboot-mode.c
index b4076b10b893..a646aefa041b 100644
--- a/drivers/power/reset/reboot-mode.c
+++ b/drivers/power/reset/reboot-mode.c
@@ -19,11 +19,10 @@ struct mode_info {
 	struct list_head list;
 };
 
-static unsigned int get_reboot_mode_magic(struct reboot_mode_driver *reboot,
-					  const char *cmd)
+static bool get_reboot_mode_magic(struct reboot_mode_driver *reboot,
+					  const char *cmd, unsigned int *magic)
 {
 	const char *normal = "normal";
-	int magic = 0;
 	struct mode_info *info;
 
 	if (!cmd)
@@ -31,12 +30,12 @@ static unsigned int get_reboot_mode_magic(struct reboot_mode_driver *reboot,
 
 	list_for_each_entry(info, &reboot->head, list) {
 		if (!strcmp(info->mode, cmd)) {
-			magic = info->magic;
-			break;
+			*magic = info->magic;
+			return true;
 		}
 	}
 
-	return magic;
+	return false;
 }
 
 static int reboot_mode_notify(struct notifier_block *this,
@@ -46,8 +45,7 @@ static int reboot_mode_notify(struct notifier_block *this,
 	unsigned int magic;
 
 	reboot = container_of(this, struct reboot_mode_driver, reboot_notifier);
-	magic = get_reboot_mode_magic(reboot, cmd);
-	if (magic)
+	if (get_reboot_mode_magic(reboot, cmd, &magic))
 		reboot->write(reboot, magic);
 
 	return NOTIFY_DONE;
-- 
2.41.0