linux-kernel - [PATCH v3 3/7] watchdog: npcm: Enable clock if provided

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Message-Id: <20220508194333.2170161-4-j.neuschaefer@gmx.net>
Date:   Sun,  8 May 2022 21:43:28 +0200
From:   Jonathan Neuschäfer <j.neuschaefer@....net>
To:     linux-clk@...r.kernel.org, openbmc@...ts.ozlabs.org
Cc:     linux-kernel@...r.kernel.org, linux-watchdog@...r.kernel.org,
        devicetree@...r.kernel.org,
        Jonathan Neuschäfer <j.neuschaefer@....net>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Avi Fishman <avifishman70@...il.com>,
        Tomer Maimon <tmaimon77@...il.com>,
        Tali Perry <tali.perry1@...il.com>,
        Patrick Venture <venture@...gle.com>,
        Nancy Yuen <yuenn@...gle.com>,
        Benjamin Fair <benjaminfair@...gle.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Guenter Roeck <linux@...ck-us.net>
Subject: [PATCH v3 3/7] watchdog: npcm: Enable clock if provided

On the Nuvoton WPCM450 SoC, with its upcoming clock driver, peripheral
clocks are individually gated and ungated. Therefore, the watchdog
driver must be able to ungate the watchdog clock.

Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@....net>
---

v3:
- Add enable/disable calls to npcm_wdt_restart handler
- Not applied due to the above change:  Acked-by: Guenter Roeck <linux@...ck-us.net>

v2:
- https://lore.kernel.org/lkml/20220429172030.398011-4-j.neuschaefer@gmx.net/
- Add clk_disable_unprepare call, suggested by Guenter Roeck

v1:
- https://lore.kernel.org/lkml/20220422183012.444674-4-j.neuschaefer@gmx.net/
---
 drivers/watchdog/npcm_wdt.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/drivers/watchdog/npcm_wdt.c b/drivers/watchdog/npcm_wdt.c
index 28a24caa2627c..a1240a906ef2a 100644
--- a/drivers/watchdog/npcm_wdt.c
+++ b/drivers/watchdog/npcm_wdt.c
@@ -3,6 +3,7 @@
 // Copyright (c) 2018 IBM Corp.

 #include <linux/bitops.h>
+#include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/interrupt.h>
 #include <linux/kernel.h>
@@ -43,6 +44,7 @@
 struct npcm_wdt {
 	struct watchdog_device  wdd;
 	void __iomem		*reg;
+	struct clk		*clk;
 };

 static inline struct npcm_wdt *to_npcm_wdt(struct watchdog_device *wdd)
@@ -66,6 +68,9 @@ static int npcm_wdt_start(struct watchdog_device *wdd)
 	struct npcm_wdt *wdt = to_npcm_wdt(wdd);
 	u32 val;

+	if (wdt->clk)
+		clk_prepare_enable(wdt->clk);
+
 	if (wdd->timeout < 2)
 		val = 0x800;
 	else if (wdd->timeout < 3)
@@ -100,6 +105,9 @@ static int npcm_wdt_stop(struct watchdog_device *wdd)

 	writel(0, wdt->reg);

+	if (wdt->clk)
+		clk_disable_unprepare(wdt->clk);
+
 	return 0;
 }

@@ -147,9 +155,15 @@ static int npcm_wdt_restart(struct watchdog_device *wdd,
 {
 	struct npcm_wdt *wdt = to_npcm_wdt(wdd);

+	if (wdt->clk)
+		clk_prepare_enable(wdt->clk);
+
 	writel(NPCM_WTR | NPCM_WTRE | NPCM_WTE, wdt->reg);
 	udelay(1000);

+	if (wdt->clk)
+		clk_disable_unprepare(wdt->clk);
+
 	return 0;
 }

@@ -191,6 +205,10 @@ static int npcm_wdt_probe(struct platform_device *pdev)
 	if (IS_ERR(wdt->reg))
 		return PTR_ERR(wdt->reg);

+	wdt->clk = devm_clk_get_optional(&pdev->dev, NULL);
+	if (IS_ERR(wdt->clk))
+		return PTR_ERR(wdt->clk);
+
 	irq = platform_get_irq(pdev, 0);
 	if (irq < 0)
 		return irq;
--
2.35.1