/*
   * Power key driver for SiRF PrimaII
   *
   * Copyright (c) 2013 - 2014 Cambridge Silicon Radio Limited, a CSR plc group
   * company.
   *
   * Licensed under GPLv2 or later.
   */
  
  #include <linux/module.h>
  #include <linux/interrupt.h>
  #include <linux/delay.h>
  #include <linux/platform_device.h>
  #include <linux/input.h>
  #include <linux/rtc/sirfsoc_rtciobrg.h>
  #include <linux/of.h>
  #include <linux/workqueue.h>
  
  struct sirfsoc_pwrc_drvdata {
  	u32			pwrc_base;
  	struct input_dev	*input;
  	struct delayed_work	work;
  };
  
  #define PWRC_ON_KEY_BIT			(1 << 0)
  
  #define PWRC_INT_STATUS			0xc
  #define PWRC_INT_MASK			0x10
  #define PWRC_PIN_STATUS			0x14
  #define PWRC_KEY_DETECT_UP_TIME		20	/* ms*/
  
  static int sirfsoc_pwrc_is_on_key_down(struct sirfsoc_pwrc_drvdata *pwrcdrv)
  {
  	u32 state = sirfsoc_rtc_iobrg_readl(pwrcdrv->pwrc_base +
  							PWRC_PIN_STATUS);
  	return !(state & PWRC_ON_KEY_BIT); /* ON_KEY is active low */
  }
  
  static void sirfsoc_pwrc_report_event(struct work_struct *work)
  {
  	struct sirfsoc_pwrc_drvdata *pwrcdrv =
  		container_of(work, struct sirfsoc_pwrc_drvdata, work.work);
  
  	if (sirfsoc_pwrc_is_on_key_down(pwrcdrv)) {
  		schedule_delayed_work(&pwrcdrv->work,
  			msecs_to_jiffies(PWRC_KEY_DETECT_UP_TIME));
  	} else {
  		input_event(pwrcdrv->input, EV_KEY, KEY_POWER, 0);
  		input_sync(pwrcdrv->input);
  	}
  }
  
  static irqreturn_t sirfsoc_pwrc_isr(int irq, void *dev_id)
  {
  	struct sirfsoc_pwrc_drvdata *pwrcdrv = dev_id;
  	u32 int_status;
  
  	int_status = sirfsoc_rtc_iobrg_readl(pwrcdrv->pwrc_base +
  							PWRC_INT_STATUS);
  	sirfsoc_rtc_iobrg_writel(int_status & ~PWRC_ON_KEY_BIT,
  				 pwrcdrv->pwrc_base + PWRC_INT_STATUS);
  
  	input_event(pwrcdrv->input, EV_KEY, KEY_POWER, 1);
  	input_sync(pwrcdrv->input);
  	schedule_delayed_work(&pwrcdrv->work,
  			      msecs_to_jiffies(PWRC_KEY_DETECT_UP_TIME));
  
  	return IRQ_HANDLED;
  }
  
  static void sirfsoc_pwrc_toggle_interrupts(struct sirfsoc_pwrc_drvdata *pwrcdrv,
  					   bool enable)
  {
  	u32 int_mask;
  
  	int_mask = sirfsoc_rtc_iobrg_readl(pwrcdrv->pwrc_base + PWRC_INT_MASK);
  	if (enable)
  		int_mask |= PWRC_ON_KEY_BIT;
  	else
  		int_mask &= ~PWRC_ON_KEY_BIT;
  	sirfsoc_rtc_iobrg_writel(int_mask, pwrcdrv->pwrc_base + PWRC_INT_MASK);
  }
  
  static int sirfsoc_pwrc_open(struct input_dev *input)
  {
  	struct sirfsoc_pwrc_drvdata *pwrcdrv = input_get_drvdata(input);
  
  	sirfsoc_pwrc_toggle_interrupts(pwrcdrv, true);
  
  	return 0;
  }
  
  static void sirfsoc_pwrc_close(struct input_dev *input)
  {
  	struct sirfsoc_pwrc_drvdata *pwrcdrv = input_get_drvdata(input);
  
  	sirfsoc_pwrc_toggle_interrupts(pwrcdrv, false);
  	cancel_delayed_work_sync(&pwrcdrv->work);
  }
  
  static const struct of_device_id sirfsoc_pwrc_of_match[] = {
  	{ .compatible = "sirf,prima2-pwrc" },
  	{},
  }
  MODULE_DEVICE_TABLE(of, sirfsoc_pwrc_of_match);
  
  static int sirfsoc_pwrc_probe(struct platform_device *pdev)
  {
  	struct device_node *np = pdev->dev.of_node;
  	struct sirfsoc_pwrc_drvdata *pwrcdrv;
  	int irq;
  	int error;
  
  	pwrcdrv = devm_kzalloc(&pdev->dev, sizeof(struct sirfsoc_pwrc_drvdata),
  			       GFP_KERNEL);
  	if (!pwrcdrv) {
  		dev_info(&pdev->dev, "Not enough memory for the device data
  ");
  		return -ENOMEM;
  	}
  
  	/*
  	 * We can't use of_iomap because pwrc is not mapped in memory,
  	 * the so-called base address is only offset in rtciobrg
  	 */
  	error = of_property_read_u32(np, "reg", &pwrcdrv->pwrc_base);
  	if (error) {
  		dev_err(&pdev->dev,
  			"unable to find base address of pwrc node in dtb
  ");
  		return error;
  	}
  
  	pwrcdrv->input = devm_input_allocate_device(&pdev->dev);
  	if (!pwrcdrv->input)
  		return -ENOMEM;
  
  	pwrcdrv->input->name = "sirfsoc pwrckey";
  	pwrcdrv->input->phys = "pwrc/input0";
  	pwrcdrv->input->evbit[0] = BIT_MASK(EV_KEY);
  	input_set_capability(pwrcdrv->input, EV_KEY, KEY_POWER);
  
  	INIT_DELAYED_WORK(&pwrcdrv->work, sirfsoc_pwrc_report_event);
  
  	pwrcdrv->input->open = sirfsoc_pwrc_open;
  	pwrcdrv->input->close = sirfsoc_pwrc_close;
  
  	input_set_drvdata(pwrcdrv->input, pwrcdrv);
  
  	/* Make sure the device is quiesced */
  	sirfsoc_pwrc_toggle_interrupts(pwrcdrv, false);
  
  	irq = platform_get_irq(pdev, 0);
  	error = devm_request_irq(&pdev->dev, irq,
  				 sirfsoc_pwrc_isr, 0,
  				 "sirfsoc_pwrc_int", pwrcdrv);
  	if (error) {
  		dev_err(&pdev->dev, "unable to claim irq %d, error: %d
  ",
  			irq, error);
  		return error;
  	}
  
  	error = input_register_device(pwrcdrv->input);
  	if (error) {
  		dev_err(&pdev->dev,
  			"unable to register input device, error: %d
  ",
  			error);
  		return error;
  	}
  
  	dev_set_drvdata(&pdev->dev, pwrcdrv);
  	device_init_wakeup(&pdev->dev, 1);
  
  	return 0;
  }
  
  static int sirfsoc_pwrc_remove(struct platform_device *pdev)
  {
  	device_init_wakeup(&pdev->dev, 0);
  
  	return 0;
  }
  
  static int __maybe_unused sirfsoc_pwrc_resume(struct device *dev)
  {
  	struct sirfsoc_pwrc_drvdata *pwrcdrv = dev_get_drvdata(dev);
  	struct input_dev *input = pwrcdrv->input;
  
  	/*
  	 * Do not mask pwrc interrupt as we want pwrc work as a wakeup source
  	 * if users touch X_ONKEY_B, see arch/arm/mach-prima2/pm.c
  	 */
  	mutex_lock(&input->mutex);
  	if (input->users)
  		sirfsoc_pwrc_toggle_interrupts(pwrcdrv, true);
  	mutex_unlock(&input->mutex);
  
  	return 0;
  }
  
  static SIMPLE_DEV_PM_OPS(sirfsoc_pwrc_pm_ops, NULL, sirfsoc_pwrc_resume);
  
  static struct platform_driver sirfsoc_pwrc_driver = {
  	.probe		= sirfsoc_pwrc_probe,
  	.remove		= sirfsoc_pwrc_remove,
  	.driver		= {
  		.name	= "sirfsoc-pwrc",
  		.pm	= &sirfsoc_pwrc_pm_ops,
  		.of_match_table = sirfsoc_pwrc_of_match,
  	}
  };
  
  module_platform_driver(sirfsoc_pwrc_driver);
  
  MODULE_LICENSE("GPL v2");
  MODULE_AUTHOR("Binghua Duan <Binghua.Duan@csr.com>, Xianglong Du <Xianglong.Du@csr.com>");
  MODULE_DESCRIPTION("CSR Prima2 PWRC Driver");
  MODULE_ALIAS("platform:sirfsoc-pwrc");