text: // 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;
  	u32 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;
  	}
  
  	/*
  	 * The response data from SCU firmware is 4 bytes,
  	 * but ONLY the first byte is the key state, other
  	 * 3 bytes could be some dirty data, so we should
  	 * ONLY take the first byte as key state.
  	 */
  	state = (bool)(msg.state & 0xff);
  
  	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 void imx_sc_key_action(void *data)
  {
  	struct imx_key_drv_data *priv = data;
  
  	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);
  }
  
  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;
  	}
  
  	error = devm_add_action_or_reset(&pdev->dev, imx_sc_key_action, &priv);
  	if (error)
  		return error;
  
  	priv->key_notifier.notifier_call = imx_sc_key_notify;
  	error = imx_scu_irq_register_notifier(&priv->key_notifier);
  	if (error)
  		dev_err(&pdev->dev, "failed to register scu notifier\n");
  
  	return error;
  }
  
  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,
  };
  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");
  