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From:   Evan Benn <evanbenn@chromium.org>
To:     Daniel Lezcano <daniel.lezcano@linaro.org>,
        Matthias Brugger <matthias.bgg@gmail.com>
Cc:     LKML <linux-kernel@vger.kernel.org>,
        Fabien Parent <fparent@baylibre.com>,
        Viresh Kumar <viresh.kumar@linaro.org>,
        Yingjoe Chen <yingjoe.chen@mediatek.com>,
        Stanley Chu <stanley.chu@mediatek.com>,
        Julia Lawall <Julia.Lawall@lip6.fr>,
        linux-mediatek@lists.infradead.org,
        linux-arm-kernel@lists.infradead.org,
        Thomas Gleixner <tglx@linutronix.de>,
        Evan Benn <evanbenn@chromium.org>
Subject: [PATCH v4] drivers/clocksource/mediatek: Ack and disable interrupts on suspend
Date:   Wed, 12 May 2021 12:25:44 +1000
Message-Id: <20210512122528.v4.1.I1d9917047de06715da16e1620759f703fcfdcbcb@changeid>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Interrupts are disabled during suspend before this driver disables its
timers. ARM trusted firmware will abort suspend if the timer irq is
pending, so ack and disable the timer interrupt during suspend.

Signed-off-by: Evan Benn <evanbenn@chromium.org>
---

Changes in v4:
Fix the comment style.

Changes in v3:
Move the ACK from the shutdown to the suspend function.

Changes in v2:
Remove the patch that splits the drivers into 2 files.

 drivers/clocksource/timer-mediatek.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/drivers/clocksource/timer-mediatek.c b/drivers/clocksource/timer-mediatek.c
index 9318edcd8963..ab63b95e414f 100644
--- a/drivers/clocksource/timer-mediatek.c
+++ b/drivers/clocksource/timer-mediatek.c
@@ -241,6 +241,28 @@ static void mtk_gpt_enable_irq(struct timer_of *to, u8 timer)
 	       timer_of_base(to) + GPT_IRQ_EN_REG);
 }
 
+static void mtk_gpt_resume(struct clock_event_device *clk)
+{
+	struct timer_of *to = to_timer_of(clk);
+
+	mtk_gpt_enable_irq(to, TIMER_CLK_EVT);
+}
+
+static void mtk_gpt_suspend(struct clock_event_device *clk)
+{
+	struct timer_of *to = to_timer_of(clk);
+
+	/* Disable all interrupts */
+	writel(0x0, timer_of_base(to) + GPT_IRQ_EN_REG);
+
+	/*
+	 * This is called with interrupts disabled,
+	 * so we need to ack any interrupt that is pending
+	 * or for example ATF will prevent a suspend from completing.
+	 */
+	writel(0x3f, timer_of_base(to) + GPT_IRQ_ACK_REG);
+}
+
 static struct timer_of to = {
 	.flags = TIMER_OF_IRQ | TIMER_OF_BASE | TIMER_OF_CLOCK,
 
@@ -286,6 +308,8 @@ static int __init mtk_gpt_init(struct device_node *node)
 	to.clkevt.set_state_oneshot = mtk_gpt_clkevt_shutdown;
 	to.clkevt.tick_resume = mtk_gpt_clkevt_shutdown;
 	to.clkevt.set_next_event = mtk_gpt_clkevt_next_event;
+	to.clkevt.suspend = mtk_gpt_suspend;
+	to.clkevt.resume = mtk_gpt_resume;
 	to.of_irq.handler = mtk_gpt_interrupt;
 
 	ret = timer_of_init(node, &to);
-- 
2.31.1.607.g51e8a6a459-goog