Input: keyboard - imx_sc: Add i.MX system controller key support

i.MX8QXP is an ARMv8 SoC which has a Cortex-M4 system controller
inside, the system controller is in charge of controlling power,
clock and scu key etc..

Adds i.MX system controller key driver support, Linux kernel has
to communicate with system controller via MU (message unit) IPC
to get scu key's status.

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/1570412509-7893-2-git-send-email-Anson.Huang@nxp.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt

@@ -155,6 +155,15 @@ Required properties:
 Optional properties:
 - timeout-sec: contains the watchdog timeout in seconds.
 
+SCU key bindings based on SCU Message Protocol
+------------------------------------------------------------
+
+Required properties:
+- compatible: should be:
+              "fsl,imx8qxp-sc-key"
+              followed by "fsl,imx-sc-key";
+- linux,keycodes: See Documentation/devicetree/bindings/input/keys.txt
+
 Example (imx8qxp):
 -------------
 aliases {
@@ -218,6 +227,11 @@ firmware {
 			compatible = "fsl,imx8qxp-sc-rtc";
 		};
 
+		scu_key: scu-key {
+			compatible = "fsl,imx8qxp-sc-key", "fsl,imx-sc-key";
+			linux,keycodes = <KEY_POWER>;
+		};
+
 		watchdog {
 			compatible = "fsl,imx8qxp-sc-wdt", "fsl,imx-sc-wdt";
 			timeout-sec = <60>;

drivers/input/keyboard/Kconfig

@@ -469,6 +469,16 @@ config KEYBOARD_IMX
 	  To compile this driver as a module, choose M here: the
 	  module will be called imx_keypad.
 
+config KEYBOARD_IMX_SC_KEY
+	tristate "IMX SCU Key Driver"
+	depends on IMX_SCU
+	help
+	  This is the system controller key driver for NXP i.MX SoCs with
+	  system controller inside.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called imx_sc_key.
+
 config KEYBOARD_NEWTON
 	tristate "Newton keyboard"
 	select SERIO

drivers/input/keyboard/Makefile

@@ -29,6 +29,7 @@ obj-$(CONFIG_KEYBOARD_HIL)		+= hil_kbd.o
 obj-$(CONFIG_KEYBOARD_HIL_OLD)		+= hilkbd.o
 obj-$(CONFIG_KEYBOARD_IPAQ_MICRO)	+= ipaq-micro-keys.o
 obj-$(CONFIG_KEYBOARD_IMX)		+= imx_keypad.o
+obj-$(CONFIG_KEYBOARD_IMX_SC_KEY)	+= imx_sc_key.o
 obj-$(CONFIG_KEYBOARD_HP6XX)		+= jornada680_kbd.o
 obj-$(CONFIG_KEYBOARD_HP7XX)		+= jornada720_kbd.o
 obj-$(CONFIG_KEYBOARD_LKKBD)		+= lkkbd.o

drivers/input/keyboard/imx_sc_key.c

@@ -0,0 +1,187 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2019 NXP.
+ */
+
+#include <linux/err.h>
+#include <linux/device.h>
+#include <linux/firmware/imx/sci.h>
+#include <linux/init.h>
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/jiffies.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+
+#define DEBOUNCE_TIME				30
+#define REPEAT_INTERVAL				60
+
+#define SC_IRQ_BUTTON				1
+#define SC_IRQ_GROUP_WAKE			3
+
+#define IMX_SC_MISC_FUNC_GET_BUTTON_STATUS	18
+
+struct imx_key_drv_data {
+	u32 keycode;
+	bool keystate;  /* true: pressed, false: released */
+	struct delayed_work check_work;
+	struct input_dev *input;
+	struct imx_sc_ipc *key_ipc_handle;
+	struct notifier_block key_notifier;
+};
+
+struct imx_sc_msg_key {
+	struct imx_sc_rpc_msg hdr;
+	u8 state;
+};
+
+static int imx_sc_key_notify(struct notifier_block *nb,
+			     unsigned long event, void *group)
+{
+	struct imx_key_drv_data *priv =
+				 container_of(nb,
+					      struct imx_key_drv_data,
+					      key_notifier);
+
+	if ((event & SC_IRQ_BUTTON) && (*(u8 *)group == SC_IRQ_GROUP_WAKE)) {
+		schedule_delayed_work(&priv->check_work,
+				      msecs_to_jiffies(DEBOUNCE_TIME));
+		pm_wakeup_event(priv->input->dev.parent, 0);
+	}
+
+	return 0;
+}
+
+static void imx_sc_check_for_events(struct work_struct *work)
+{
+	struct imx_key_drv_data *priv =
+				 container_of(work,
+					      struct imx_key_drv_data,
+					      check_work.work);
+	struct input_dev *input = priv->input;
+	struct imx_sc_msg_key msg;
+	struct imx_sc_rpc_msg *hdr = &msg.hdr;
+	bool state;
+	int error;
+
+	hdr->ver = IMX_SC_RPC_VERSION;
+	hdr->svc = IMX_SC_RPC_SVC_MISC;
+	hdr->func = IMX_SC_MISC_FUNC_GET_BUTTON_STATUS;
+	hdr->size = 1;
+
+	error = imx_scu_call_rpc(priv->key_ipc_handle, &msg, true);
+	if (error) {
+		dev_err(&input->dev, "read imx sc key failed, error %d\n", error);
+		return;
+	}
+
+	state = (bool)msg.state;
+
+	if (state ^ priv->keystate) {
+		priv->keystate = state;
+		input_event(input, EV_KEY, priv->keycode, state);
+		input_sync(input);
+		if (!priv->keystate)
+			pm_relax(priv->input->dev.parent);
+	}
+
+	if (state)
+		schedule_delayed_work(&priv->check_work,
+				      msecs_to_jiffies(REPEAT_INTERVAL));
+}
+
+static int imx_sc_key_probe(struct platform_device *pdev)
+{
+	struct imx_key_drv_data *priv;
+	struct input_dev *input;
+	int error;
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	error = imx_scu_get_handle(&priv->key_ipc_handle);
+	if (error)
+		return error;
+
+	if (device_property_read_u32(&pdev->dev, "linux,keycodes",
+				     &priv->keycode)) {
+		dev_err(&pdev->dev, "missing linux,keycodes property\n");
+		return -EINVAL;
+	}
+
+	INIT_DELAYED_WORK(&priv->check_work, imx_sc_check_for_events);
+
+	input = devm_input_allocate_device(&pdev->dev);
+	if (!input) {
+		dev_err(&pdev->dev, "failed to allocate the input device\n");
+		return -ENOMEM;
+	}
+
+	input->name = pdev->name;
+	input->phys = "imx-sc-key/input0";
+	input->id.bustype = BUS_HOST;
+
+	input_set_capability(input, EV_KEY, priv->keycode);
+
+	error = input_register_device(input);
+	if (error) {
+		dev_err(&pdev->dev, "failed to register input device\n");
+		return error;
+	}
+
+	priv->input = input;
+	platform_set_drvdata(pdev, priv);
+
+	error = imx_scu_irq_group_enable(SC_IRQ_GROUP_WAKE, SC_IRQ_BUTTON,
+					 true);
+	if (error) {
+		dev_err(&pdev->dev, "failed to enable scu group irq\n");
+		return error;
+	}
+
+	priv->key_notifier.notifier_call = imx_sc_key_notify;
+	error = imx_scu_irq_register_notifier(&priv->key_notifier);
+	if (error) {
+		imx_scu_irq_group_enable(SC_IRQ_GROUP_WAKE, SC_IRQ_BUTTON,
+					 false);
+		dev_err(&pdev->dev, "failed to register scu notifier\n");
+		return error;
+	}
+
+	return 0;
+}
+
+static int imx_sc_key_remove(struct platform_device *pdev)
+{
+	struct imx_key_drv_data *priv = platform_get_drvdata(pdev);
+
+	imx_scu_irq_group_enable(SC_IRQ_GROUP_WAKE, SC_IRQ_BUTTON, false);
+	imx_scu_irq_unregister_notifier(&priv->key_notifier);
+	cancel_delayed_work_sync(&priv->check_work);
+
+	return 0;
+}
+
+static const struct of_device_id imx_sc_key_ids[] = {
+	{ .compatible = "fsl,imx-sc-key" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, imx_sc_key_ids);
+
+static struct platform_driver imx_sc_key_driver = {
+	.driver = {
+		.name = "imx-sc-key",
+		.of_match_table = imx_sc_key_ids,
+	},
+	.probe = imx_sc_key_probe,
+	.remove = imx_sc_key_remove,
+};
+module_platform_driver(imx_sc_key_driver);
+
+MODULE_AUTHOR("Anson Huang <Anson.Huang@nxp.com>");
+MODULE_DESCRIPTION("i.MX System Controller Key Driver");
+MODULE_LICENSE("GPL v2");