[PATCH 2/3] Input: snvs_pwrkey - enable snvs clock as needed

["André Draszik" <git@andred.net>]

At the moment, enabling this driver without the SNVS RTC driver
being active will hang the kernel as soon as the power button
is pressed.

The reason is that in that case the SNVS isn't enabled, and
any attempt to read the SNVS registers will simply hang forever.

Ensure the clock is enabled (during the interrupt handler) to
make this driver work.

Also see commit 7f8993995410 ("drivers/rtc/rtc-snvs: add clock support")
and commit edb190cb1734
("rtc: snvs: make sure clock is enabled for interrupt handle")
for similar updates to the snvs rtc driver.

Signed-off-by: André Draszik <git@andred.net>
Cc: Anson Huang <Anson.Huang@nxp.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: "Horia Geantă" <horia.geanta@nxp.com>
Cc: Aymen Sghaier <aymen.sghaier@nxp.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: linux-crypto@vger.kernel.org
Cc: devicetree@vger.kernel.org
Cc: linux-input@vger.kernel.org
---
 drivers/input/keyboard/snvs_pwrkey.c | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/drivers/input/keyboard/snvs_pwrkey.c b/drivers/input/keyboard/snvs_pwrkey.c
index 2f5e3ab5ed63..c29711d8735c 100644
--- a/drivers/input/keyboard/snvs_pwrkey.c
+++ b/drivers/input/keyboard/snvs_pwrkey.c
@@ -16,6 +16,7 @@
 #include <linux/of_address.h>
 #include <linux/platform_device.h>
 #include <linux/pm_wakeirq.h>
+#include <linux/clk.h>
 #include <linux/mfd/syscon.h>
 #include <linux/regmap.h>
 
@@ -38,6 +39,7 @@ struct pwrkey_drv_data {
 	int wakeup;
 	struct timer_list check_timer;
 	struct input_dev *input;
+	struct clk *clk;
 	u8 minor_rev;
 };
 
@@ -72,6 +74,9 @@ static irqreturn_t imx_snvs_pwrkey_interrupt(int irq, void *dev_id)
 	struct input_dev *input = pdata->input;
 	u32 lp_status;
 
+	if (pdata->clk)
+		clk_enable(pdata->clk);
+
 	pm_wakeup_event(input->dev.parent, 0);
 
 	regmap_read(pdata->snvs, SNVS_LPSR_REG, &lp_status);
@@ -96,6 +101,9 @@ static irqreturn_t imx_snvs_pwrkey_interrupt(int irq, void *dev_id)
 	/* clear SPO status */
 	regmap_write(pdata->snvs, SNVS_LPSR_REG, SNVS_LPSR_SPO);
 
+	if (pdata->clk)
+		clk_disable(pdata->clk);
+
 	return IRQ_HANDLED;
 }
 
@@ -140,6 +148,25 @@ static int imx_snvs_pwrkey_probe(struct platform_device *pdev)
 	if (pdata->irq < 0)
 		return -EINVAL;
 
+	pdata->clk = devm_clk_get(&pdev->dev, "snvs-pwrkey");
+	if (IS_ERR(pdata->clk)) {
+		pdata->clk = NULL;
+	} else {
+		error = clk_prepare_enable(pdata->clk);
+		if (error) {
+			dev_err(&pdev->dev,
+				"Could not prepare or enable the snvs clock\n");
+			return error;
+		}
+		error = devm_add_action_or_reset(&pdev->dev,
+				(void(*)(void *))clk_disable_unprepare,
+				pdata->clk);
+		if (error) {
+			dev_err(&pdev->dev, "failed to add reset action on 'snvs-pwrkey'");
+			return error;
+		}
+	}
+
 	regmap_read(pdata->snvs, SNVS_HPVIDR1_REG, &vid);
 	pdata->minor_rev = vid & 0xff;
 
-- 
2.23.0.rc1