Input: snvs_pwrkey - send key events for i.MX6 S, DL and Q

The first generation i.MX6 processors does not send an interrupt when the
power key is pressed. It sends a power down request interrupt if the key is
released before a hard shutdown (5 second press). This should allow
software to bring down the SoC safely.

For this driver to work as a regular power key with the older SoCs, we need
to send a keypress AND release when we get the power down request irq.
Signed-off-by: Robin van der Gracht <robin@protonic.nl>
Link: https://lore.kernel.org/r/20191125161210.8275-1-robin@protonic.nlSigned-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/keyboard/Kconfig

@@ -450,7 +450,7 @@ config KEYBOARD_SNVS_PWRKEY
 	depends on OF
 	help
 	  This is the snvs powerkey driver for the Freescale i.MX application
-	  processors that are newer than i.MX6 SX.
+	  processors.
 
 	  To compile this driver as a module, choose M here; the
 	  module will be called snvs_pwrkey.

drivers/input/keyboard/snvs_pwrkey.c

@@ -19,6 +19,7 @@
 #include <linux/mfd/syscon.h>
 #include <linux/regmap.h>
 
+#define SNVS_HPVIDR1_REG	0xF8
 #define SNVS_LPSR_REG		0x4C	/* LP Status Register */
 #define SNVS_LPCR_REG		0x38	/* LP Control Register */
 #define SNVS_HPSR_REG		0x14
@@ -37,6 +38,7 @@ struct pwrkey_drv_data {
 	int wakeup;
 	struct timer_list check_timer;
 	struct input_dev *input;
+	u8 minor_rev;
 };
 
 static void imx_imx_snvs_check_for_events(struct timer_list *t)
@@ -67,13 +69,29 @@ static irqreturn_t imx_snvs_pwrkey_interrupt(int irq, void *dev_id)
 {
 	struct platform_device *pdev = dev_id;
 	struct pwrkey_drv_data *pdata = platform_get_drvdata(pdev);
+	struct input_dev *input = pdata->input;
 	u32 lp_status;
 
-	pm_wakeup_event(pdata->input->dev.parent, 0);
+	pm_wakeup_event(input->dev.parent, 0);
 
 	regmap_read(pdata->snvs, SNVS_LPSR_REG, &lp_status);
-	if (lp_status & SNVS_LPSR_SPO)
-		mod_timer(&pdata->check_timer, jiffies + msecs_to_jiffies(DEBOUNCE_TIME));
+	if (lp_status & SNVS_LPSR_SPO) {
+		if (pdata->minor_rev == 0) {
+			/*
+			 * The first generation i.MX6 SoCs only sends an
+			 * interrupt on button release. To mimic power-key
+			 * usage, we'll prepend a press event.
+			 */
+			input_report_key(input, pdata->keycode, 1);
+			input_sync(input);
+			input_report_key(input, pdata->keycode, 0);
+			input_sync(input);
+			pm_relax(input->dev.parent);
+		} else {
+			mod_timer(&pdata->check_timer,
+			          jiffies + msecs_to_jiffies(DEBOUNCE_TIME));
+		}
+	}
 
 	/* clear SPO status */
 	regmap_write(pdata->snvs, SNVS_LPSR_REG, SNVS_LPSR_SPO);
@@ -94,6 +112,7 @@ static int imx_snvs_pwrkey_probe(struct platform_device *pdev)
 	struct input_dev *input = NULL;
 	struct device_node *np;
 	int error;
+	u32 vid;
 
 	/* Get SNVS register Page */
 	np = pdev->dev.of_node;
@@ -121,6 +140,9 @@ static int imx_snvs_pwrkey_probe(struct platform_device *pdev)
 	if (pdata->irq < 0)
 		return -EINVAL;
 
+	regmap_read(pdata->snvs, SNVS_HPVIDR1_REG, &vid);
+	pdata->minor_rev = vid & 0xff;
+
 	regmap_update_bits(pdata->snvs, SNVS_LPCR_REG, SNVS_LPCR_DEP_EN, SNVS_LPCR_DEP_EN);
 
 	/* clear the unexpected interrupt before driver ready */