[PATCH v2 5/6] 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: "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: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: NXP Linux Team <linux-imx@nxp.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Anson Huang <Anson.Huang@nxp.com>
Cc: Robin Gong <yibin.gong@nxp.com>
Cc: linux-crypto@vger.kernel.org
Cc: devicetree@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-input@vger.kernel.org

---
v2:
* drop redundant tests and simplify error handling by using
  devm_clk_get_optional()
* add clock handling to imx_imx_snvs_check_for_events()
---
 drivers/input/keyboard/snvs_pwrkey.c | 28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/drivers/input/keyboard/snvs_pwrkey.c b/drivers/input/keyboard/snvs_pwrkey.c
index 2f5e3ab5ed63..382d2ae82c9b 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;
 };
 
@@ -47,7 +49,10 @@ static void imx_imx_snvs_check_for_events(struct timer_list *t)
 	struct input_dev *input = pdata->input;
 	u32 state;
 
+	clk_enable(pdata->clk);
 	regmap_read(pdata->snvs, SNVS_HPSR_REG, &state);
+	clk_disable(pdata->clk);
+
 	state = state & SNVS_HPSR_BTN ? 1 : 0;
 
 	/* only report new event if status changed */
@@ -74,11 +79,13 @@ static irqreturn_t imx_snvs_pwrkey_interrupt(int irq, void *dev_id)
 
 	pm_wakeup_event(input->dev.parent, 0);
 
+	clk_enable(pdata->clk);
+
 	regmap_read(pdata->snvs, SNVS_LPSR_REG, &lp_status);
 	if (lp_status & SNVS_LPSR_SPO) {
 		if (pdata->minor_rev == 0) {
 			/*
-			 * The first generation i.MX6 SoCs only sends an
+			 * The first generation i.MX[6|7] SoCs only send an
 			 * interrupt on button release. To mimic power-key
 			 * usage, we'll prepend a press event.
 			 */
@@ -96,6 +103,8 @@ 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);
 
+	clk_disable(pdata->clk);
+
 	return IRQ_HANDLED;
 }
 
@@ -140,6 +149,23 @@ static int imx_snvs_pwrkey_probe(struct platform_device *pdev)
 	if (pdata->irq < 0)
 		return -EINVAL;
 
+	pdata->clk = devm_clk_get_optional(&pdev->dev, "snvs-pwrkey");
+	if (IS_ERR(pdata->clk))
+		return PTR_ERR(pdata->clk);
+
+	error = clk_prepare(pdata->clk);
+	if (error) {
+		dev_err(&pdev->dev, "failed to prepare the snvs clock\n");
+		return error;
+	}
+	error = devm_add_action_or_reset(&pdev->dev,
+			(void(*)(void *))clk_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