/*
   * Driver for the IMX SNVS ON/OFF Power Key
   * Copyright (C) 2015 Freescale Semiconductor, Inc. All Rights Reserved.
   *
   * The code contained herein is licensed under the GNU General Public
   * License. You may obtain a copy of the GNU General Public License
   * Version 2 or later at the following locations:
   *
   * http://www.opensource.org/licenses/gpl-license.html
   * http://www.gnu.org/copyleft/gpl.html
   */
  
  #include <linux/device.h>
  #include <linux/err.h>
  #include <linux/init.h>
  #include <linux/input.h>
  #include <linux/interrupt.h>
  #include <linux/io.h>
  #include <linux/jiffies.h>
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/of.h>
  #include <linux/of_address.h>
  #include <linux/platform_device.h>
  #include <linux/mfd/syscon.h>
  #include <linux/regmap.h>
  
  #define SNVS_LPSR_REG	0x4C	/* LP Status Register */
  #define SNVS_LPCR_REG	0x38	/* LP Control Register */
  #define SNVS_HPSR_REG	0x14
  #define SNVS_HPSR_BTN	BIT(6)
  #define SNVS_LPSR_SPO	BIT(18)
  #define SNVS_LPCR_DEP_EN BIT(5)
  
  #define DEBOUNCE_TIME 30
  #define REPEAT_INTERVAL 60
  
  struct pwrkey_drv_data {
  	struct regmap *snvs;
  	int irq;
  	int keycode;
  	int keystate;  /* 1:pressed */
  	int wakeup;
  	struct timer_list check_timer;
  	struct input_dev *input;
  };
  
  static void imx_imx_snvs_check_for_events(unsigned long data)
  {
  	struct pwrkey_drv_data *pdata = (struct pwrkey_drv_data *) data;
  	struct input_dev *input = pdata->input;
  	u32 state;
  
  	regmap_read(pdata->snvs, SNVS_HPSR_REG, &state);
  	state = state & SNVS_HPSR_BTN ? 1 : 0;
  
  	/* only report new event if status changed */
  	if (state ^ pdata->keystate) {
  		pdata->keystate = state;
  		input_event(input, EV_KEY, pdata->keycode, state);
  		input_sync(input);
  		pm_relax(pdata->input->dev.parent);
  	}
  
  	/* repeat check if pressed long */
  	if (state) {
  		mod_timer(&pdata->check_timer,
  			  jiffies + msecs_to_jiffies(REPEAT_INTERVAL));
  	}
  }
  
  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);
  	u32 lp_status;
  
  	pm_wakeup_event(pdata->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));
  
  	/* clear SPO status */
  	regmap_write(pdata->snvs, SNVS_LPSR_REG, SNVS_LPSR_SPO);
  
  	return IRQ_HANDLED;
  }
  
  static void imx_snvs_pwrkey_act(void *pdata)
  {
  	struct pwrkey_drv_data *pd = pdata;
  
  	del_timer_sync(&pd->check_timer);
  }
  
  static int imx_snvs_pwrkey_probe(struct platform_device *pdev)
  {
  	struct pwrkey_drv_data *pdata = NULL;
  	struct input_dev *input = NULL;
  	struct device_node *np;
  	int error;
  
  	/* Get SNVS register Page */
  	np = pdev->dev.of_node;
  	if (!np)
  		return -ENODEV;
  
  	pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
  	if (!pdata)
  		return -ENOMEM;
  
  	pdata->snvs = syscon_regmap_lookup_by_phandle(np, "regmap");
  	if (!pdata->snvs) {
  		dev_err(&pdev->dev, "Can't get snvs syscon
  ");
  		return -ENODEV;
  	}
  
  	if (of_property_read_u32(np, "linux,keycode", &pdata->keycode)) {
  		pdata->keycode = KEY_POWER;
  		dev_warn(&pdev->dev, "KEY_POWER without setting in dts
  ");
  	}
  
  	pdata->wakeup = of_property_read_bool(np, "wakeup-source");
  
  	pdata->irq = platform_get_irq(pdev, 0);
  	if (pdata->irq < 0) {
  		dev_err(&pdev->dev, "no irq defined in platform data
  ");
  		return -EINVAL;
  	}
  
  	regmap_update_bits(pdata->snvs, SNVS_LPCR_REG, SNVS_LPCR_DEP_EN, SNVS_LPCR_DEP_EN);
  
  	/* clear the unexpected interrupt before driver ready */
  	regmap_write(pdata->snvs, SNVS_LPSR_REG, SNVS_LPSR_SPO);
  
  	setup_timer(&pdata->check_timer,
  		    imx_imx_snvs_check_for_events, (unsigned long) pdata);
  
  	input = devm_input_allocate_device(&pdev->dev);
  	if (!input) {
  		dev_err(&pdev->dev, "failed to allocate the input device
  ");
  		return -ENOMEM;
  	}
  
  	input->name = pdev->name;
  	input->phys = "snvs-pwrkey/input0";
  	input->id.bustype = BUS_HOST;
  
  	input_set_capability(input, EV_KEY, pdata->keycode);
  
  	/* input customer action to cancel release timer */
  	error = devm_add_action(&pdev->dev, imx_snvs_pwrkey_act, pdata);
  	if (error) {
  		dev_err(&pdev->dev, "failed to register remove action
  ");
  		return error;
  	}
  
  	error = devm_request_irq(&pdev->dev, pdata->irq,
  			       imx_snvs_pwrkey_interrupt,
  			       0, pdev->name, pdev);
  
  	if (error) {
  		dev_err(&pdev->dev, "interrupt not available.
  ");
  		return error;
  	}
  
  	error = input_register_device(input);
  	if (error < 0) {
  		dev_err(&pdev->dev, "failed to register input device
  ");
  		input_free_device(input);
  		return error;
  	}
  
  	pdata->input = input;
  	platform_set_drvdata(pdev, pdata);
  
  	device_init_wakeup(&pdev->dev, pdata->wakeup);
  
  	return 0;
  }
  
  static int imx_snvs_pwrkey_suspend(struct device *dev)
  {
  	struct platform_device *pdev = to_platform_device(dev);
  	struct pwrkey_drv_data *pdata = platform_get_drvdata(pdev);
  
  	if (device_may_wakeup(&pdev->dev))
  		enable_irq_wake(pdata->irq);
  
  	return 0;
  }
  
  static int imx_snvs_pwrkey_resume(struct device *dev)
  {
  	struct platform_device *pdev = to_platform_device(dev);
  	struct pwrkey_drv_data *pdata = platform_get_drvdata(pdev);
  
  	if (device_may_wakeup(&pdev->dev))
  		disable_irq_wake(pdata->irq);
  
  	return 0;
  }
  
  static const struct of_device_id imx_snvs_pwrkey_ids[] = {
  	{ .compatible = "fsl,sec-v4.0-pwrkey" },
  	{ /* sentinel */ }
  };
  MODULE_DEVICE_TABLE(of, imx_snvs_pwrkey_ids);
  
  static SIMPLE_DEV_PM_OPS(imx_snvs_pwrkey_pm_ops, imx_snvs_pwrkey_suspend,
  				imx_snvs_pwrkey_resume);
  
  static struct platform_driver imx_snvs_pwrkey_driver = {
  	.driver = {
  		.name = "snvs_pwrkey",
  		.pm     = &imx_snvs_pwrkey_pm_ops,
  		.of_match_table = imx_snvs_pwrkey_ids,
  	},
  	.probe = imx_snvs_pwrkey_probe,
  };
  module_platform_driver(imx_snvs_pwrkey_driver);
  
  MODULE_AUTHOR("Freescale Semiconductor");
  MODULE_DESCRIPTION("i.MX snvs power key Driver");
  MODULE_LICENSE("GPL");