1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
3 | * Driver for the SGS-Thomson M48T35 Timekeeper RAM chip |
4 | * |
5 | * Copyright (C) 2000 Silicon Graphics, Inc. |
6 | * Written by Ulf Carlsson (ulfc@engr.sgi.com) |
7 | * |
8 | * Copyright (C) 2008 Thomas Bogendoerfer |
9 | * |
10 | * Based on code written by Paul Gortmaker. |
11 | */ |
12 | |
13 | #include <linux/module.h> |
14 | #include <linux/rtc.h> |
15 | #include <linux/slab.h> |
16 | #include <linux/platform_device.h> |
17 | #include <linux/bcd.h> |
18 | #include <linux/io.h> |
19 | #include <linux/err.h> |
20 | |
21 | struct m48t35_rtc { |
22 | u8 pad[0x7ff8]; /* starts at 0x7ff8 */ |
23 | #ifdef CONFIG_SGI_IP27 |
24 | u8 hour; |
25 | u8 min; |
26 | u8 sec; |
27 | u8 control; |
28 | u8 year; |
29 | u8 month; |
30 | u8 date; |
31 | u8 day; |
32 | #else |
33 | u8 control; |
34 | u8 sec; |
35 | u8 min; |
36 | u8 hour; |
37 | u8 day; |
38 | u8 date; |
39 | u8 month; |
40 | u8 year; |
41 | #endif |
42 | }; |
43 | |
44 | #define M48T35_RTC_SET 0x80 |
45 | #define M48T35_RTC_READ 0x40 |
46 | |
47 | struct m48t35_priv { |
48 | struct rtc_device *rtc; |
49 | struct m48t35_rtc __iomem *reg; |
50 | size_t size; |
51 | unsigned long baseaddr; |
52 | spinlock_t lock; |
53 | }; |
54 | |
55 | static int m48t35_read_time(struct device *dev, struct rtc_time *tm) |
56 | { |
57 | struct m48t35_priv *priv = dev_get_drvdata(dev); |
58 | u8 control; |
59 | |
60 | /* |
61 | * Only the values that we read from the RTC are set. We leave |
62 | * tm_wday, tm_yday and tm_isdst untouched. Even though the |
63 | * RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated |
64 | * by the RTC when initially set to a non-zero value. |
65 | */ |
66 | spin_lock_irq(lock: &priv->lock); |
67 | control = readb(addr: &priv->reg->control); |
68 | writeb(val: control | M48T35_RTC_READ, addr: &priv->reg->control); |
69 | tm->tm_sec = readb(addr: &priv->reg->sec); |
70 | tm->tm_min = readb(addr: &priv->reg->min); |
71 | tm->tm_hour = readb(addr: &priv->reg->hour); |
72 | tm->tm_mday = readb(addr: &priv->reg->date); |
73 | tm->tm_mon = readb(addr: &priv->reg->month); |
74 | tm->tm_year = readb(addr: &priv->reg->year); |
75 | writeb(val: control, addr: &priv->reg->control); |
76 | spin_unlock_irq(lock: &priv->lock); |
77 | |
78 | tm->tm_sec = bcd2bin(tm->tm_sec); |
79 | tm->tm_min = bcd2bin(tm->tm_min); |
80 | tm->tm_hour = bcd2bin(tm->tm_hour); |
81 | tm->tm_mday = bcd2bin(tm->tm_mday); |
82 | tm->tm_mon = bcd2bin(tm->tm_mon); |
83 | tm->tm_year = bcd2bin(tm->tm_year); |
84 | |
85 | /* |
86 | * Account for differences between how the RTC uses the values |
87 | * and how they are defined in a struct rtc_time; |
88 | */ |
89 | tm->tm_year += 70; |
90 | if (tm->tm_year <= 69) |
91 | tm->tm_year += 100; |
92 | |
93 | tm->tm_mon--; |
94 | return 0; |
95 | } |
96 | |
97 | static int m48t35_set_time(struct device *dev, struct rtc_time *tm) |
98 | { |
99 | struct m48t35_priv *priv = dev_get_drvdata(dev); |
100 | unsigned char mon, day, hrs, min, sec; |
101 | unsigned int yrs; |
102 | u8 control; |
103 | |
104 | yrs = tm->tm_year + 1900; |
105 | mon = tm->tm_mon + 1; /* tm_mon starts at zero */ |
106 | day = tm->tm_mday; |
107 | hrs = tm->tm_hour; |
108 | min = tm->tm_min; |
109 | sec = tm->tm_sec; |
110 | |
111 | if (yrs < 1970) |
112 | return -EINVAL; |
113 | |
114 | yrs -= 1970; |
115 | if (yrs > 255) /* They are unsigned */ |
116 | return -EINVAL; |
117 | |
118 | if (yrs > 169) |
119 | return -EINVAL; |
120 | |
121 | if (yrs >= 100) |
122 | yrs -= 100; |
123 | |
124 | sec = bin2bcd(sec); |
125 | min = bin2bcd(min); |
126 | hrs = bin2bcd(hrs); |
127 | day = bin2bcd(day); |
128 | mon = bin2bcd(mon); |
129 | yrs = bin2bcd(yrs); |
130 | |
131 | spin_lock_irq(lock: &priv->lock); |
132 | control = readb(addr: &priv->reg->control); |
133 | writeb(val: control | M48T35_RTC_SET, addr: &priv->reg->control); |
134 | writeb(val: yrs, addr: &priv->reg->year); |
135 | writeb(val: mon, addr: &priv->reg->month); |
136 | writeb(val: day, addr: &priv->reg->date); |
137 | writeb(val: hrs, addr: &priv->reg->hour); |
138 | writeb(val: min, addr: &priv->reg->min); |
139 | writeb(val: sec, addr: &priv->reg->sec); |
140 | writeb(val: control, addr: &priv->reg->control); |
141 | spin_unlock_irq(lock: &priv->lock); |
142 | return 0; |
143 | } |
144 | |
145 | static const struct rtc_class_ops m48t35_ops = { |
146 | .read_time = m48t35_read_time, |
147 | .set_time = m48t35_set_time, |
148 | }; |
149 | |
150 | static int m48t35_probe(struct platform_device *pdev) |
151 | { |
152 | struct resource *res; |
153 | struct m48t35_priv *priv; |
154 | |
155 | res = platform_get_resource(pdev, IORESOURCE_MEM, 0); |
156 | if (!res) |
157 | return -ENODEV; |
158 | priv = devm_kzalloc(dev: &pdev->dev, size: sizeof(struct m48t35_priv), GFP_KERNEL); |
159 | if (!priv) |
160 | return -ENOMEM; |
161 | |
162 | priv->size = resource_size(res); |
163 | if (!devm_request_mem_region(&pdev->dev, res->start, priv->size, |
164 | pdev->name)) |
165 | return -EBUSY; |
166 | |
167 | priv->baseaddr = res->start; |
168 | priv->reg = devm_ioremap(dev: &pdev->dev, offset: priv->baseaddr, size: priv->size); |
169 | if (!priv->reg) |
170 | return -ENOMEM; |
171 | |
172 | spin_lock_init(&priv->lock); |
173 | |
174 | platform_set_drvdata(pdev, data: priv); |
175 | |
176 | priv->rtc = devm_rtc_device_register(dev: &pdev->dev, name: "m48t35" , |
177 | ops: &m48t35_ops, THIS_MODULE); |
178 | return PTR_ERR_OR_ZERO(ptr: priv->rtc); |
179 | } |
180 | |
181 | static struct platform_driver m48t35_platform_driver = { |
182 | .driver = { |
183 | .name = "rtc-m48t35" , |
184 | }, |
185 | .probe = m48t35_probe, |
186 | }; |
187 | |
188 | module_platform_driver(m48t35_platform_driver); |
189 | |
190 | MODULE_AUTHOR("Thomas Bogendoerfer <tsbogend@alpha.franken.de>" ); |
191 | MODULE_DESCRIPTION("M48T35 RTC driver" ); |
192 | MODULE_LICENSE("GPL" ); |
193 | MODULE_ALIAS("platform:rtc-m48t35" ); |
194 | |