/*
   * IBM OPAL RTC driver
   * Copyright (C) 2014 IBM
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation; either version 2 of the License, or
   * (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program.
   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #define DRVNAME		"rtc-opal"

  
  #include <linux/module.h>
  #include <linux/err.h>
  #include <linux/rtc.h>
  #include <linux/delay.h>
  #include <linux/bcd.h>
  #include <linux/platform_device.h>
  #include <linux/of.h>
  #include <asm/opal.h>
  #include <asm/firmware.h>
  
  static void opal_to_tm(u32 y_m_d, u64 h_m_s_ms, struct rtc_time *tm)
  {
  	tm->tm_year = ((bcd2bin(y_m_d >> 24) * 100) +
  		       bcd2bin((y_m_d >> 16) & 0xff)) - 1900;
  	tm->tm_mon  = bcd2bin((y_m_d >> 8) & 0xff) - 1;
  	tm->tm_mday = bcd2bin(y_m_d & 0xff);
  	tm->tm_hour = bcd2bin((h_m_s_ms >> 56) & 0xff);
  	tm->tm_min  = bcd2bin((h_m_s_ms >> 48) & 0xff);
  	tm->tm_sec  = bcd2bin((h_m_s_ms >> 40) & 0xff);

  	tm->tm_wday = -1;

  }
  
  static void tm_to_opal(struct rtc_time *tm, u32 *y_m_d, u64 *h_m_s_ms)
  {
  	*y_m_d |= ((u32)bin2bcd((tm->tm_year + 1900) / 100)) << 24;
  	*y_m_d |= ((u32)bin2bcd((tm->tm_year + 1900) % 100)) << 16;
  	*y_m_d |= ((u32)bin2bcd((tm->tm_mon + 1))) << 8;
  	*y_m_d |= ((u32)bin2bcd(tm->tm_mday));
  
  	*h_m_s_ms |= ((u64)bin2bcd(tm->tm_hour)) << 56;
  	*h_m_s_ms |= ((u64)bin2bcd(tm->tm_min)) << 48;
  	*h_m_s_ms |= ((u64)bin2bcd(tm->tm_sec)) << 40;
  }
  
  static int opal_get_rtc_time(struct device *dev, struct rtc_time *tm)
  {
  	long rc = OPAL_BUSY;
  	u32 y_m_d;
  	u64 h_m_s_ms;
  	__be32 __y_m_d;
  	__be64 __h_m_s_ms;
  
  	while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) {
  		rc = opal_rtc_read(&__y_m_d, &__h_m_s_ms);
  		if (rc == OPAL_BUSY_EVENT)
  			opal_poll_events(NULL);
  		else
  			msleep(10);
  	}
  
  	if (rc != OPAL_SUCCESS)
  		return -EIO;
  
  	y_m_d = be32_to_cpu(__y_m_d);
  	h_m_s_ms = be64_to_cpu(__h_m_s_ms);
  	opal_to_tm(y_m_d, h_m_s_ms, tm);
  
  	return 0;
  }
  
  static int opal_set_rtc_time(struct device *dev, struct rtc_time *tm)
  {
  	long rc = OPAL_BUSY;
  	u32 y_m_d = 0;
  	u64 h_m_s_ms = 0;
  
  	tm_to_opal(tm, &y_m_d, &h_m_s_ms);
  	while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) {
  		rc = opal_rtc_write(y_m_d, h_m_s_ms);
  		if (rc == OPAL_BUSY_EVENT)
  			opal_poll_events(NULL);
  		else
  			msleep(10);
  	}
  
  	return rc == OPAL_SUCCESS ? 0 : -EIO;
  }
  
  /*
   * TPO	Timed Power-On
   *
   * TPO get/set OPAL calls care about the hour and min and to make it consistent
   * with the rtc utility time conversion functions, we use the 'u64' to store
   * its value and perform bit shift by 32 before use..
   */
  static int opal_get_tpo_time(struct device *dev, struct rtc_wkalrm *alarm)
  {
  	__be32 __y_m_d, __h_m;
  	struct opal_msg msg;
  	int rc, token;
  	u64 h_m_s_ms;
  	u32 y_m_d;
  
  	token = opal_async_get_token_interruptible();
  	if (token < 0) {
  		if (token != -ERESTARTSYS)
  			pr_err("Failed to get the async token
  ");
  
  		return token;
  	}
  
  	rc = opal_tpo_read(token, &__y_m_d, &__h_m);
  	if (rc != OPAL_ASYNC_COMPLETION) {
  		rc = -EIO;
  		goto exit;
  	}
  
  	rc = opal_async_wait_response(token, &msg);
  	if (rc) {
  		rc = -EIO;
  		goto exit;
  	}

  	rc = opal_get_async_rc(msg);

  	if (rc != OPAL_SUCCESS) {
  		rc = -EIO;
  		goto exit;
  	}
  
  	y_m_d = be32_to_cpu(__y_m_d);
  	h_m_s_ms = ((u64)be32_to_cpu(__h_m) << 32);
  	opal_to_tm(y_m_d, h_m_s_ms, &alarm->time);
  
  exit:
  	opal_async_release_token(token);
  	return rc;
  }
  
  /* Set Timed Power-On */
  static int opal_set_tpo_time(struct device *dev, struct rtc_wkalrm *alarm)
  {

  	u64 h_m_s_ms = 0;

  	struct opal_msg msg;
  	u32 y_m_d = 0;

  	int token, rc;

  
  	tm_to_opal(&alarm->time, &y_m_d, &h_m_s_ms);
  
  	token = opal_async_get_token_interruptible();
  	if (token < 0) {
  		if (token != -ERESTARTSYS)
  			pr_err("Failed to get the async token
  ");
  
  		return token;
  	}
  
  	/* TPO, we care about hour and minute */
  	rc = opal_tpo_write(token, y_m_d,
  			    (u32)((h_m_s_ms >> 32) & 0xffff0000));
  	if (rc != OPAL_ASYNC_COMPLETION) {
  		rc = -EIO;
  		goto exit;
  	}
  
  	rc = opal_async_wait_response(token, &msg);
  	if (rc) {
  		rc = -EIO;
  		goto exit;
  	}

  	rc = opal_get_async_rc(msg);

  	if (rc != OPAL_SUCCESS)
  		rc = -EIO;
  
  exit:
  	opal_async_release_token(token);
  	return rc;
  }

  static struct rtc_class_ops opal_rtc_ops = {

  	.read_time	= opal_get_rtc_time,
  	.set_time	= opal_set_rtc_time,

  };
  
  static int opal_rtc_probe(struct platform_device *pdev)
  {
  	struct rtc_device *rtc;

  	if (pdev->dev.of_node &&
  	    (of_property_read_bool(pdev->dev.of_node, "wakeup-source") ||
  	     of_property_read_bool(pdev->dev.of_node, "has-tpo")/* legacy */)) {

  		device_set_wakeup_capable(&pdev->dev, true);

  		opal_rtc_ops.read_alarm	= opal_get_tpo_time;
  		opal_rtc_ops.set_alarm = opal_set_tpo_time;
  	}

  
  	rtc = devm_rtc_device_register(&pdev->dev, DRVNAME, &opal_rtc_ops,
  				       THIS_MODULE);
  	if (IS_ERR(rtc))
  		return PTR_ERR(rtc);
  
  	rtc->uie_unsupported = 1;
  
  	return 0;
  }
  
  static const struct of_device_id opal_rtc_match[] = {
  	{
  		.compatible	= "ibm,opal-rtc",
  	},
  	{ }
  };
  MODULE_DEVICE_TABLE(of, opal_rtc_match);
  
  static const struct platform_device_id opal_rtc_driver_ids[] = {
  	{
  		.name		= "opal-rtc",
  	},
  	{ }
  };
  MODULE_DEVICE_TABLE(platform, opal_rtc_driver_ids);
  
  static struct platform_driver opal_rtc_driver = {
  	.probe		= opal_rtc_probe,
  	.id_table	= opal_rtc_driver_ids,
  	.driver		= {
  		.name		= DRVNAME,

  		.of_match_table	= opal_rtc_match,
  	},
  };
  
  static int __init opal_rtc_init(void)
  {
  	if (!firmware_has_feature(FW_FEATURE_OPAL))
  		return -ENODEV;
  
  	return platform_driver_register(&opal_rtc_driver);
  }
  
  static void __exit opal_rtc_exit(void)
  {
  	platform_driver_unregister(&opal_rtc_driver);
  }
  
  MODULE_AUTHOR("Neelesh Gupta <neelegup@linux.vnet.ibm.com>");
  MODULE_DESCRIPTION("IBM OPAL RTC driver");
  MODULE_LICENSE("GPL");
  
  module_init(opal_rtc_init);
  module_exit(opal_rtc_exit);