tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * Driver for the SGS-Thomson M48T35 Timekeeper RAM chip
3 *
4 * Copyright (C) 2000 Silicon Graphics, Inc.
5 * Written by Ulf Carlsson (ulfc@engr.sgi.com)
6 *
7 * Copyright (C) 2008 Thomas Bogendoerfer
8 *
9 * Based on code written by Paul Gortmaker.
10 *
11 * This program is free software; you can redistribute it and/or modify it
12 * under the terms of the GNU General Public License as published by the
13 * Free Software Foundation; either version 2 of the License, or (at your
14 * option) any later version.
15 */
16
17#include <linux/module.h>
18#include <linux/rtc.h>
19#include <linux/slab.h>
20#include <linux/platform_device.h>
21#include <linux/bcd.h>
22#include <linux/io.h>
23#include <linux/err.h>
24
25struct m48t35_rtc {
26 u8 pad[0x7ff8]; /* starts at 0x7ff8 */
27 u8 control;
28 u8 sec;
29 u8 min;
30 u8 hour;
31 u8 day;
32 u8 date;
33 u8 month;
34 u8 year;
35};
36
37#define M48T35_RTC_SET 0x80
38#define M48T35_RTC_READ 0x40
39
40struct m48t35_priv {
41 struct rtc_device *rtc;
42 struct m48t35_rtc __iomem *reg;
43 size_t size;
44 unsigned long baseaddr;
45 spinlock_t lock;
46};
47
48static int m48t35_read_time(struct device *dev, struct rtc_time *tm)
49{
50 struct m48t35_priv *priv = dev_get_drvdata(dev);
51 u8 control;
52
53 /*
54 * Only the values that we read from the RTC are set. We leave
55 * tm_wday, tm_yday and tm_isdst untouched. Even though the
56 * RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated
57 * by the RTC when initially set to a non-zero value.
58 */
59 spin_lock_irq(&priv->lock);
60 control = readb(&priv->reg->control);
61 writeb(control | M48T35_RTC_READ, &priv->reg->control);
62 tm->tm_sec = readb(&priv->reg->sec);
63 tm->tm_min = readb(&priv->reg->min);
64 tm->tm_hour = readb(&priv->reg->hour);
65 tm->tm_mday = readb(&priv->reg->date);
66 tm->tm_mon = readb(&priv->reg->month);
67 tm->tm_year = readb(&priv->reg->year);
68 writeb(control, &priv->reg->control);
69 spin_unlock_irq(&priv->lock);
70
71 tm->tm_sec = bcd2bin(tm->tm_sec);
72 tm->tm_min = bcd2bin(tm->tm_min);
73 tm->tm_hour = bcd2bin(tm->tm_hour);
74 tm->tm_mday = bcd2bin(tm->tm_mday);
75 tm->tm_mon = bcd2bin(tm->tm_mon);
76 tm->tm_year = bcd2bin(tm->tm_year);
77
78 /*
79 * Account for differences between how the RTC uses the values
80 * and how they are defined in a struct rtc_time;
81 */
82 tm->tm_year += 70;
83 if (tm->tm_year <= 69)
84 tm->tm_year += 100;
85
86 tm->tm_mon--;
87 return 0;
88}
89
90static int m48t35_set_time(struct device *dev, struct rtc_time *tm)
91{
92 struct m48t35_priv *priv = dev_get_drvdata(dev);
93 unsigned char mon, day, hrs, min, sec;
94 unsigned int yrs;
95 u8 control;
96
97 yrs = tm->tm_year + 1900;
98 mon = tm->tm_mon + 1; /* tm_mon starts at zero */
99 day = tm->tm_mday;
100 hrs = tm->tm_hour;
101 min = tm->tm_min;
102 sec = tm->tm_sec;
103
104 if (yrs < 1970)
105 return -EINVAL;
106
107 yrs -= 1970;
108 if (yrs > 255) /* They are unsigned */
109 return -EINVAL;
110
111 if (yrs > 169)
112 return -EINVAL;
113
114 if (yrs >= 100)
115 yrs -= 100;
116
117 sec = bin2bcd(sec);
118 min = bin2bcd(min);
119 hrs = bin2bcd(hrs);
120 day = bin2bcd(day);
121 mon = bin2bcd(mon);
122 yrs = bin2bcd(yrs);
123
124 spin_lock_irq(&priv->lock);
125 control = readb(&priv->reg->control);
126 writeb(control | M48T35_RTC_SET, &priv->reg->control);
127 writeb(yrs, &priv->reg->year);
128 writeb(mon, &priv->reg->month);
129 writeb(day, &priv->reg->date);
130 writeb(hrs, &priv->reg->hour);
131 writeb(min, &priv->reg->min);
132 writeb(sec, &priv->reg->sec);
133 writeb(control, &priv->reg->control);
134 spin_unlock_irq(&priv->lock);
135 return 0;
136}
137
138static const struct rtc_class_ops m48t35_ops = {
139 .read_time = m48t35_read_time,
140 .set_time = m48t35_set_time,
141};
142
143static int m48t35_probe(struct platform_device *pdev)
144{
145 struct resource *res;
146 struct m48t35_priv *priv;
147
148 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
149 if (!res)
150 return -ENODEV;
151 priv = devm_kzalloc(&pdev->dev, sizeof(struct m48t35_priv), GFP_KERNEL);
152 if (!priv)
153 return -ENOMEM;
154
155 priv->size = resource_size(res);
156 /*
157 * kludge: remove the #ifndef after ioc3 resource
158 * conflicts are resolved
159 */
160#ifndef CONFIG_SGI_IP27
161 if (!devm_request_mem_region(&pdev->dev, res->start, priv->size,
162 pdev->name))
163 return -EBUSY;
164#endif
165 priv->baseaddr = res->start;
166 priv->reg = devm_ioremap(&pdev->dev, priv->baseaddr, priv->size);
167 if (!priv->reg)
168 return -ENOMEM;
169
170 spin_lock_init(&priv->lock);
171
172 platform_set_drvdata(pdev, priv);
173
174 priv->rtc = devm_rtc_device_register(&pdev->dev, "m48t35",
175 &m48t35_ops, THIS_MODULE);
176 return PTR_ERR_OR_ZERO(priv->rtc);
177}
178
179static struct platform_driver m48t35_platform_driver = {
180 .driver = {
181 .name = "rtc-m48t35",
182 },
183 .probe = m48t35_probe,
184};
185
186module_platform_driver(m48t35_platform_driver);
187
188MODULE_AUTHOR("Thomas Bogendoerfer <tsbogend@alpha.franken.de>");
189MODULE_DESCRIPTION("M48T35 RTC driver");
190MODULE_LICENSE("GPL");
191MODULE_ALIAS("platform:rtc-m48t35");