1/*
  2 *  Gemini OnChip RTC
  3 *
  4 *  Copyright (C) 2009 Janos Laube <janos.dev@gmail.com>
  5 *
  6 * This program is free software; you can redistribute it and/or modify
  7 * it under the terms of the GNU General Public License as published by
  8 * the Free Software Foundation; either version 2 of the License, or
  9 * (at your option) any later version.
 10 *
 11 * This program is distributed in the hope that it will be useful,
 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 14 * GNU General Public License for more details.
 15 *
 16 * Original code for older kernel 2.6.15 are from Stormlinksemi
 17 * first update from Janos Laube for > 2.6.29 kernels
 18 *
 19 * checkpatch fixes and usage of rtc-lib code
 20 * Hans Ulli Kroll <ulli.kroll@googlemail.com>
 21 */
 22
 23#include <linux/rtc.h>
 24#include <linux/io.h>
 25#include <linux/slab.h>
 26#include <linux/platform_device.h>
 27#include <linux/kernel.h>
 28#include <linux/module.h>
 29
 30#define DRV_NAME        "rtc-gemini"
 31#define DRV_VERSION     "0.2"
 32
 33MODULE_AUTHOR("Hans Ulli Kroll <ulli.kroll@googlemail.com>");
 34MODULE_DESCRIPTION("RTC driver for Gemini SoC");
 35MODULE_LICENSE("GPL");
 36MODULE_ALIAS("platform:" DRV_NAME);
 37
 38struct gemini_rtc {
 39	struct rtc_device	*rtc_dev;
 40	void __iomem		*rtc_base;
 41	int			rtc_irq;
 42};
 43
 44enum gemini_rtc_offsets {
 45	GEMINI_RTC_SECOND	= 0x00,
 46	GEMINI_RTC_MINUTE	= 0x04,
 47	GEMINI_RTC_HOUR		= 0x08,
 48	GEMINI_RTC_DAYS		= 0x0C,
 49	GEMINI_RTC_ALARM_SECOND	= 0x10,
 50	GEMINI_RTC_ALARM_MINUTE	= 0x14,
 51	GEMINI_RTC_ALARM_HOUR	= 0x18,
 52	GEMINI_RTC_RECORD	= 0x1C,
 53	GEMINI_RTC_CR		= 0x20
 54};
 55
 56static irqreturn_t gemini_rtc_interrupt(int irq, void *dev)
 57{
 58	return IRQ_HANDLED;
 59}
 60
 61/*
 62 * Looks like the RTC in the Gemini SoC is (totaly) broken
 63 * We can't read/write directly the time from RTC registers.
 64 * We must do some "offset" calculation to get the real time
 65 *
 66 * This FIX works pretty fine and Stormlinksemi aka Cortina-Networks does
 67 * the same thing, without the rtc-lib.c calls.
 68 */
 69
 70static int gemini_rtc_read_time(struct device *dev, struct rtc_time *tm)
 71{
 72	struct gemini_rtc *rtc = dev_get_drvdata(dev);
 73
 74	unsigned int  days, hour, min, sec;
 75	unsigned long offset, time;
 76
 77	sec  = readl(rtc->rtc_base + GEMINI_RTC_SECOND);
 78	min  = readl(rtc->rtc_base + GEMINI_RTC_MINUTE);
 79	hour = readl(rtc->rtc_base + GEMINI_RTC_HOUR);
 80	days = readl(rtc->rtc_base + GEMINI_RTC_DAYS);
 81	offset = readl(rtc->rtc_base + GEMINI_RTC_RECORD);
 82
 83	time = offset + days * 86400 + hour * 3600 + min * 60 + sec;
 84
 85	rtc_time_to_tm(time, tm);
 86
 87	return 0;
 88}
 89
 90static int gemini_rtc_set_time(struct device *dev, struct rtc_time *tm)
 91{
 92	struct gemini_rtc *rtc = dev_get_drvdata(dev);
 93	unsigned int sec, min, hour, day;
 94	unsigned long offset, time;
 95
 96	if (tm->tm_year >= 2148)	/* EPOCH Year + 179 */
 97		return -EINVAL;
 98
 99	rtc_tm_to_time(tm, &time);
100
101	sec = readl(rtc->rtc_base + GEMINI_RTC_SECOND);
102	min = readl(rtc->rtc_base + GEMINI_RTC_MINUTE);
103	hour = readl(rtc->rtc_base + GEMINI_RTC_HOUR);
104	day = readl(rtc->rtc_base + GEMINI_RTC_DAYS);
105
106	offset = time - (day * 86400 + hour * 3600 + min * 60 + sec);
107
108	writel(offset, rtc->rtc_base + GEMINI_RTC_RECORD);
109	writel(0x01, rtc->rtc_base + GEMINI_RTC_CR);
110
111	return 0;
112}
113
114static struct rtc_class_ops gemini_rtc_ops = {
115	.read_time     = gemini_rtc_read_time,
116	.set_time      = gemini_rtc_set_time,
117};
118
119static int gemini_rtc_probe(struct platform_device *pdev)
120{
121	struct gemini_rtc *rtc;
122	struct device *dev = &pdev->dev;
123	struct resource *res;
124	int ret;
125
126	rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
127	if (unlikely(!rtc))
128		return -ENOMEM;
129	platform_set_drvdata(pdev, rtc);
130
131	res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
132	if (!res)
133		return -ENODEV;
134
135	rtc->rtc_irq = res->start;
136
137	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
138	if (!res)
139		return -ENODEV;
140
141	rtc->rtc_base = devm_ioremap(dev, res->start,
142				     resource_size(res));
143
144	ret = devm_request_irq(dev, rtc->rtc_irq, gemini_rtc_interrupt,
145			       IRQF_SHARED, pdev->name, dev);
146	if (unlikely(ret))
147		return ret;
148
149	rtc->rtc_dev = rtc_device_register(pdev->name, dev,
150					   &gemini_rtc_ops, THIS_MODULE);
151	return PTR_ERR_OR_ZERO(rtc->rtc_dev);
152}
153
154static int gemini_rtc_remove(struct platform_device *pdev)
155{
156	struct gemini_rtc *rtc = platform_get_drvdata(pdev);
157
158	rtc_device_unregister(rtc->rtc_dev);
159
160	return 0;
161}
162
163static struct platform_driver gemini_rtc_driver = {
164	.driver		= {
165		.name	= DRV_NAME,
166	},
167	.probe		= gemini_rtc_probe,
168	.remove		= gemini_rtc_remove,
169};
170
171module_platform_driver_probe(gemini_rtc_driver, gemini_rtc_probe);