linux-kernel - [PATCH] watchdog: wdat_wdt: Avoid unimplemented get

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Message-Id: <20221221-wdat_wdt-timeleft-v1-1-8e8a314c36cc@weissschuh.net>
Date:   Thu, 22 Dec 2022 23:43:31 +0000
From:   Thomas Weißschuh <linux@...ssschuh.net>
To:     Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Guenter Roeck <linux@...ck-us.net>
Cc:     linux-watchdog@...r.kernel.org, linux-kernel@...r.kernel.org,
        Thomas Weißschuh <linux@...ssschuh.net>
Subject: [PATCH] watchdog: wdat_wdt: Avoid unimplemented get_timeleft

As per the specification the action QUERY_COUNTDOWN_PERIOD is optional.
If the action is not implemented by the physical device the driver would
always report "0" from get_timeleft().
Avoid confusing userspace by only providing get_timeleft() when
implemented by the hardware.

Signed-off-by: Thomas Weißschuh <linux@...ssschuh.net>
---
 drivers/watchdog/wdat_wdt.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/watchdog/wdat_wdt.c b/drivers/watchdog/wdat_wdt.c
index ce7a4a9e4b03..0ba99bed59fc 100644
--- a/drivers/watchdog/wdat_wdt.c
+++ b/drivers/watchdog/wdat_wdt.c
@@ -301,13 +301,12 @@ static const struct watchdog_info wdat_wdt_info = {
 	.identity = "wdat_wdt",
 };
 
-static const struct watchdog_ops wdat_wdt_ops = {
+static struct watchdog_ops wdat_wdt_ops = {
 	.owner = THIS_MODULE,
 	.start = wdat_wdt_start,
 	.stop = wdat_wdt_stop,
 	.ping = wdat_wdt_ping,
 	.set_timeout = wdat_wdt_set_timeout,
-	.get_timeleft = wdat_wdt_get_timeleft,
 };
 
 static int wdat_wdt_probe(struct platform_device *pdev)
@@ -436,6 +435,9 @@ static int wdat_wdt_probe(struct platform_device *pdev)
 		list_add_tail(&instr->node, instructions);
 	}
 
+	if (wdat->instructions[ACPI_WDAT_GET_CURRENT_COUNTDOWN])
+		wdat_wdt_ops.get_timeleft = wdat_wdt_get_timeleft;
+
 	wdat_wdt_boot_status(wdat);
 	wdat_wdt_set_running(wdat);
 

---
base-commit: 0a924817d2ed9396401e0557c6134276d2e26382
change-id: 20221221-wdat_wdt-timeleft-b38d0db39d9f

Best regards,
-- 
Thomas Weißschuh <linux@...ssschuh.net>