text: // SPDX-License-Identifier: GPL-2.0
  /*
   * Gemini power management controller
   * Copyright (C) 2017 Linus Walleij <linus.walleij@linaro.org>
   *
   * Inspired by code from the SL3516 board support by Jason Lee
   * Inspired by code from Janos Laube <janos.dev@gmail.com>
   */
  #include <linux/of.h>
  #include <linux/of_platform.h>
  #include <linux/platform_device.h>
  #include <linux/pm.h>
  #include <linux/bitops.h>
  #include <linux/interrupt.h>
  #include <linux/io.h>
  #include <linux/reboot.h>
  
  #define GEMINI_PWC_ID		0x00010500
  #define	GEMINI_PWC_IDREG	0x00
  #define	GEMINI_PWC_CTRLREG	0x04
  #define	GEMINI_PWC_STATREG	0x08
  
  #define GEMINI_CTRL_SHUTDOWN	BIT(0)
  #define GEMINI_CTRL_ENABLE	BIT(1)
  #define GEMINI_CTRL_IRQ_CLR	BIT(2)
  
  #define GEMINI_STAT_CIR		BIT(4)
  #define	GEMINI_STAT_RTC		BIT(5)
  #define	GEMINI_STAT_POWERBUTTON	BIT(6)
  
  struct gemini_powercon {
          struct device           *dev;
          void __iomem            *base;
  };
  
  static irqreturn_t gemini_powerbutton_interrupt(int irq, void *data)
  {
  	struct gemini_powercon *gpw = data;
  	u32 val;
  
  	/* ACK the IRQ */
  	val = readl(gpw->base + GEMINI_PWC_CTRLREG);
  	val |= GEMINI_CTRL_IRQ_CLR;
  	writel(val, gpw->base + GEMINI_PWC_CTRLREG);
  
  	val = readl(gpw->base + GEMINI_PWC_STATREG);
  	val &= 0x70U;
  	switch (val) {
  	case GEMINI_STAT_CIR:
  		/*
  		 * We do not yet have a driver for the infrared
  		 * controller so it can cause spurious poweroff
  		 * events. Ignore those for now.
  		 */
  		dev_info(gpw->dev, "infrared poweroff - ignored\n");
  		break;
  	case GEMINI_STAT_RTC:
  		dev_info(gpw->dev, "RTC poweroff\n");
  		orderly_poweroff(true);
  		break;
  	case GEMINI_STAT_POWERBUTTON:
  		dev_info(gpw->dev, "poweroff button pressed\n");
  		orderly_poweroff(true);
  		break;
  	default:
  		dev_info(gpw->dev, "other power management IRQ\n");
  		break;
  	}
  
  	return IRQ_HANDLED;
  }
  
  /* This callback needs this static local as it has void as argument */
  static struct gemini_powercon *gpw_poweroff;
  
  static void gemini_poweroff(void)
  {
  	struct gemini_powercon *gpw = gpw_poweroff;
  	u32 val;
  
  	dev_crit(gpw->dev, "Gemini power off\n");
  	val = readl(gpw->base + GEMINI_PWC_CTRLREG);
  	val |= GEMINI_CTRL_ENABLE | GEMINI_CTRL_IRQ_CLR;
  	writel(val, gpw->base + GEMINI_PWC_CTRLREG);
  
  	val &= ~GEMINI_CTRL_ENABLE;
  	val |= GEMINI_CTRL_SHUTDOWN;
  	writel(val, gpw->base + GEMINI_PWC_CTRLREG);
  }
  
  static int gemini_poweroff_probe(struct platform_device *pdev)
  {
  	struct device *dev = &pdev->dev;
  	struct resource *res;
  	struct gemini_powercon *gpw;
  	u32 val;
  	int irq;
  	int ret;
  
  	gpw = devm_kzalloc(dev, sizeof(*gpw), GFP_KERNEL);
  	if (!gpw)
  		return -ENOMEM;
  
  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	gpw->base = devm_ioremap_resource(dev, res);
  	if (IS_ERR(gpw->base))
  		return PTR_ERR(gpw->base);
  
  	irq = platform_get_irq(pdev, 0);
  	if (irq < 0)
  		return irq;
  
  	gpw->dev = dev;
  
  	val = readl(gpw->base + GEMINI_PWC_IDREG);
  	val &= 0xFFFFFF00U;
  	if (val != GEMINI_PWC_ID) {
  		dev_err(dev, "wrong power controller ID: %08x\n",
  			val);
  		return -ENODEV;
  	}
  
  	/*
  	 * Enable the power controller. This is crucial on Gemini
  	 * systems: if this is not done, pressing the power button
  	 * will result in unconditional poweroff without any warning.
  	 * This makes the kernel handle the poweroff.
  	 */
  	val = readl(gpw->base + GEMINI_PWC_CTRLREG);
  	val |= GEMINI_CTRL_ENABLE;
  	writel(val, gpw->base + GEMINI_PWC_CTRLREG);
  
  	/* Clear the IRQ */
  	val = readl(gpw->base + GEMINI_PWC_CTRLREG);
  	val |= GEMINI_CTRL_IRQ_CLR;
  	writel(val, gpw->base + GEMINI_PWC_CTRLREG);
  
  	/* Wait for this to clear */
  	val = readl(gpw->base + GEMINI_PWC_STATREG);
  	while (val & 0x70U)
  		val = readl(gpw->base + GEMINI_PWC_STATREG);
  
  	/* Clear the IRQ again */
  	val = readl(gpw->base + GEMINI_PWC_CTRLREG);
  	val |= GEMINI_CTRL_IRQ_CLR;
  	writel(val, gpw->base + GEMINI_PWC_CTRLREG);
  
  	ret = devm_request_irq(dev, irq, gemini_powerbutton_interrupt, 0,
  			       "poweroff", gpw);
  	if (ret)
  		return ret;
  
  	pm_power_off = gemini_poweroff;
  	gpw_poweroff = gpw;
  
  	dev_info(dev, "Gemini poweroff driver registered\n");
  
  	return 0;
  }
  
  static const struct of_device_id gemini_poweroff_of_match[] = {
  	{
  		.compatible = "cortina,gemini-power-controller",
  	},
  	{}
  };
  
  static struct platform_driver gemini_poweroff_driver = {
  	.probe = gemini_poweroff_probe,
  	.driver = {
  		.name = "gemini-poweroff",
  		.of_match_table = gemini_poweroff_of_match,
  	},
  };
  builtin_platform_driver(gemini_poweroff_driver);
  