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
 32MODULE_AUTHOR("Hans Ulli Kroll <ulli.kroll@googlemail.com>");
 33MODULE_DESCRIPTION("RTC driver for Gemini SoC");
 34MODULE_LICENSE("GPL");
 35MODULE_ALIAS("platform:" DRV_NAME);
 36
 37struct gemini_rtc {
 38	struct rtc_device	*rtc_dev;
 39	void __iomem		*rtc_base;
 40	int			rtc_irq;
 41};
 42
 43enum gemini_rtc_offsets {
 44	GEMINI_RTC_SECOND	= 0x00,
 45	GEMINI_RTC_MINUTE	= 0x04,
 46	GEMINI_RTC_HOUR		= 0x08,
 47	GEMINI_RTC_DAYS		= 0x0C,
 48	GEMINI_RTC_ALARM_SECOND	= 0x10,
 49	GEMINI_RTC_ALARM_MINUTE	= 0x14,
 50	GEMINI_RTC_ALARM_HOUR	= 0x18,
 51	GEMINI_RTC_RECORD	= 0x1C,
 52	GEMINI_RTC_CR		= 0x20
 53};
 54
 55static irqreturn_t gemini_rtc_interrupt(int irq, void *dev)
 56{
 57	return IRQ_HANDLED;
 58}
 59
 60/*
 61 * Looks like the RTC in the Gemini SoC is (totaly) broken
 62 * We can't read/write directly the time from RTC registers.
 63 * We must do some "offset" calculation to get the real time
 64 *
 65 * This FIX works pretty fine and Stormlinksemi aka Cortina-Networks does
 66 * the same thing, without the rtc-lib.c calls.
 67 */
 68
 69static int gemini_rtc_read_time(struct device *dev, struct rtc_time *tm)
 70{
 71	struct gemini_rtc *rtc = dev_get_drvdata(dev);
 72
 73	unsigned int  days, hour, min, sec;
 74	unsigned long offset, time;
 75
 76	sec  = readl(rtc->rtc_base + GEMINI_RTC_SECOND);
 77	min  = readl(rtc->rtc_base + GEMINI_RTC_MINUTE);
 78	hour = readl(rtc->rtc_base + GEMINI_RTC_HOUR);
 79	days = readl(rtc->rtc_base + GEMINI_RTC_DAYS);
 80	offset = readl(rtc->rtc_base + GEMINI_RTC_RECORD);
 81
 82	time = offset + days * 86400 + hour * 3600 + min * 60 + sec;
 83
 84	rtc_time_to_tm(time, tm);
 85
 86	return 0;
 87}
 88
 89static int gemini_rtc_set_time(struct device *dev, struct rtc_time *tm)
 90{
 91	struct gemini_rtc *rtc = dev_get_drvdata(dev);
 92	unsigned int sec, min, hour, day;
 93	unsigned long offset, time;
 94
 95	if (tm->tm_year >= 2148)	/* EPOCH Year + 179 */
 96		return -EINVAL;
 97
 98	rtc_tm_to_time(tm, &time);
 99
100	sec = readl(rtc->rtc_base + GEMINI_RTC_SECOND);
101	min = readl(rtc->rtc_base + GEMINI_RTC_MINUTE);
102	hour = readl(rtc->rtc_base + GEMINI_RTC_HOUR);
103	day = readl(rtc->rtc_base + GEMINI_RTC_DAYS);
104
105	offset = time - (day * 86400 + hour * 3600 + min * 60 + sec);
106
107	writel(offset, rtc->rtc_base + GEMINI_RTC_RECORD);
108	writel(0x01, rtc->rtc_base + GEMINI_RTC_CR);
109
110	return 0;
111}
112
113static const struct rtc_class_ops gemini_rtc_ops = {
114	.read_time     = gemini_rtc_read_time,
115	.set_time      = gemini_rtc_set_time,
116};
117
118static int gemini_rtc_probe(struct platform_device *pdev)
119{
120	struct gemini_rtc *rtc;
121	struct device *dev = &pdev->dev;
122	struct resource *res;
123	int ret;
124
125	rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
126	if (unlikely(!rtc))
127		return -ENOMEM;
128	platform_set_drvdata(pdev, rtc);
129
130	res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
131	if (!res)
132		return -ENODEV;
133
134	rtc->rtc_irq = res->start;
135
136	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
137	if (!res)
138		return -ENODEV;
139
140	rtc->rtc_base = devm_ioremap(dev, res->start,
141				     resource_size(res));
142
143	ret = devm_request_irq(dev, rtc->rtc_irq, gemini_rtc_interrupt,
144			       IRQF_SHARED, pdev->name, dev);
145	if (unlikely(ret))
146		return ret;
147
148	rtc->rtc_dev = rtc_device_register(pdev->name, dev,
149					   &gemini_rtc_ops, THIS_MODULE);
150	return PTR_ERR_OR_ZERO(rtc->rtc_dev);
151}
152
153static int gemini_rtc_remove(struct platform_device *pdev)
154{
155	struct gemini_rtc *rtc = platform_get_drvdata(pdev);
156
157	rtc_device_unregister(rtc->rtc_dev);
158
159	return 0;
160}
161
162static struct platform_driver gemini_rtc_driver = {
163	.driver		= {
164		.name	= DRV_NAME,
165	},
166	.probe		= gemini_rtc_probe,
167	.remove		= gemini_rtc_remove,
168};
169
170module_platform_driver_probe(gemini_rtc_driver, gemini_rtc_probe);