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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * ST M48T86 / Dallas DS12887 RTC driver
4 * Copyright (c) 2006 Tower Technologies
5 *
6 * Author: Alessandro Zummo <a.zummo@towertech.it>
7 *
8 * This drivers only supports the clock running in BCD and 24H mode.
9 * If it will be ever adapted to binary and 12H mode, care must be taken
10 * to not introduce bugs.
11 */
12
13#include <linux/module.h>
14#include <linux/mod_devicetable.h>
15#include <linux/rtc.h>
16#include <linux/platform_device.h>
17#include <linux/bcd.h>
18#include <linux/io.h>
19
20#define M48T86_SEC 0x00
21#define M48T86_SECALRM 0x01
22#define M48T86_MIN 0x02
23#define M48T86_MINALRM 0x03
24#define M48T86_HOUR 0x04
25#define M48T86_HOURALRM 0x05
26#define M48T86_DOW 0x06 /* 1 = sunday */
27#define M48T86_DOM 0x07
28#define M48T86_MONTH 0x08 /* 1 - 12 */
29#define M48T86_YEAR 0x09 /* 0 - 99 */
30#define M48T86_A 0x0a
31#define M48T86_B 0x0b
32#define M48T86_B_SET BIT(7)
33#define M48T86_B_DM BIT(2)
34#define M48T86_B_H24 BIT(1)
35#define M48T86_C 0x0c
36#define M48T86_D 0x0d
37#define M48T86_D_VRT BIT(7)
38#define M48T86_NVRAM(x) (0x0e + (x))
39#define M48T86_NVRAM_LEN 114
40
41struct m48t86_rtc_info {
42 void __iomem *index_reg;
43 void __iomem *data_reg;
44 struct rtc_device *rtc;
45};
46
47static unsigned char m48t86_readb(struct device *dev, unsigned long addr)
48{
49 struct m48t86_rtc_info *info = dev_get_drvdata(dev);
50 unsigned char value;
51
52 writeb(addr, info->index_reg);
53 value = readb(info->data_reg);
54
55 return value;
56}
57
58static void m48t86_writeb(struct device *dev,
59 unsigned char value, unsigned long addr)
60{
61 struct m48t86_rtc_info *info = dev_get_drvdata(dev);
62
63 writeb(addr, info->index_reg);
64 writeb(value, info->data_reg);
65}
66
67static int m48t86_rtc_read_time(struct device *dev, struct rtc_time *tm)
68{
69 unsigned char reg;
70
71 reg = m48t86_readb(dev, M48T86_B);
72
73 if (reg & M48T86_B_DM) {
74 /* data (binary) mode */
75 tm->tm_sec = m48t86_readb(dev, M48T86_SEC);
76 tm->tm_min = m48t86_readb(dev, M48T86_MIN);
77 tm->tm_hour = m48t86_readb(dev, M48T86_HOUR) & 0x3f;
78 tm->tm_mday = m48t86_readb(dev, M48T86_DOM);
79 /* tm_mon is 0-11 */
80 tm->tm_mon = m48t86_readb(dev, M48T86_MONTH) - 1;
81 tm->tm_year = m48t86_readb(dev, M48T86_YEAR) + 100;
82 tm->tm_wday = m48t86_readb(dev, M48T86_DOW);
83 } else {
84 /* bcd mode */
85 tm->tm_sec = bcd2bin(m48t86_readb(dev, M48T86_SEC));
86 tm->tm_min = bcd2bin(m48t86_readb(dev, M48T86_MIN));
87 tm->tm_hour = bcd2bin(m48t86_readb(dev, M48T86_HOUR) &
88 0x3f);
89 tm->tm_mday = bcd2bin(m48t86_readb(dev, M48T86_DOM));
90 /* tm_mon is 0-11 */
91 tm->tm_mon = bcd2bin(m48t86_readb(dev, M48T86_MONTH)) - 1;
92 tm->tm_year = bcd2bin(m48t86_readb(dev, M48T86_YEAR)) + 100;
93 tm->tm_wday = bcd2bin(m48t86_readb(dev, M48T86_DOW));
94 }
95
96 /* correct the hour if the clock is in 12h mode */
97 if (!(reg & M48T86_B_H24))
98 if (m48t86_readb(dev, M48T86_HOUR) & 0x80)
99 tm->tm_hour += 12;
100
101 return 0;
102}
103
104static int m48t86_rtc_set_time(struct device *dev, struct rtc_time *tm)
105{
106 unsigned char reg;
107
108 reg = m48t86_readb(dev, M48T86_B);
109
110 /* update flag and 24h mode */
111 reg |= M48T86_B_SET | M48T86_B_H24;
112 m48t86_writeb(dev, reg, M48T86_B);
113
114 if (reg & M48T86_B_DM) {
115 /* data (binary) mode */
116 m48t86_writeb(dev, tm->tm_sec, M48T86_SEC);
117 m48t86_writeb(dev, tm->tm_min, M48T86_MIN);
118 m48t86_writeb(dev, tm->tm_hour, M48T86_HOUR);
119 m48t86_writeb(dev, tm->tm_mday, M48T86_DOM);
120 m48t86_writeb(dev, tm->tm_mon + 1, M48T86_MONTH);
121 m48t86_writeb(dev, tm->tm_year % 100, M48T86_YEAR);
122 m48t86_writeb(dev, tm->tm_wday, M48T86_DOW);
123 } else {
124 /* bcd mode */
125 m48t86_writeb(dev, bin2bcd(tm->tm_sec), M48T86_SEC);
126 m48t86_writeb(dev, bin2bcd(tm->tm_min), M48T86_MIN);
127 m48t86_writeb(dev, bin2bcd(tm->tm_hour), M48T86_HOUR);
128 m48t86_writeb(dev, bin2bcd(tm->tm_mday), M48T86_DOM);
129 m48t86_writeb(dev, bin2bcd(tm->tm_mon + 1), M48T86_MONTH);
130 m48t86_writeb(dev, bin2bcd(tm->tm_year % 100), M48T86_YEAR);
131 m48t86_writeb(dev, bin2bcd(tm->tm_wday), M48T86_DOW);
132 }
133
134 /* update ended */
135 reg &= ~M48T86_B_SET;
136 m48t86_writeb(dev, reg, M48T86_B);
137
138 return 0;
139}
140
141static int m48t86_rtc_proc(struct device *dev, struct seq_file *seq)
142{
143 unsigned char reg;
144
145 reg = m48t86_readb(dev, M48T86_B);
146
147 seq_printf(seq, "mode\t\t: %s\n",
148 (reg & M48T86_B_DM) ? "binary" : "bcd");
149
150 reg = m48t86_readb(dev, M48T86_D);
151
152 seq_printf(seq, "battery\t\t: %s\n",
153 (reg & M48T86_D_VRT) ? "ok" : "exhausted");
154
155 return 0;
156}
157
158static const struct rtc_class_ops m48t86_rtc_ops = {
159 .read_time = m48t86_rtc_read_time,
160 .set_time = m48t86_rtc_set_time,
161 .proc = m48t86_rtc_proc,
162};
163
164static int m48t86_nvram_read(void *priv, unsigned int off, void *buf,
165 size_t count)
166{
167 struct device *dev = priv;
168 unsigned int i;
169
170 for (i = 0; i < count; i++)
171 ((u8 *)buf)[i] = m48t86_readb(dev, M48T86_NVRAM(off + i));
172
173 return 0;
174}
175
176static int m48t86_nvram_write(void *priv, unsigned int off, void *buf,
177 size_t count)
178{
179 struct device *dev = priv;
180 unsigned int i;
181
182 for (i = 0; i < count; i++)
183 m48t86_writeb(dev, ((u8 *)buf)[i], M48T86_NVRAM(off + i));
184
185 return 0;
186}
187
188/*
189 * The RTC is an optional feature at purchase time on some Technologic Systems
190 * boards. Verify that it actually exists by checking if the last two bytes
191 * of the NVRAM can be changed.
192 *
193 * This is based on the method used in their rtc7800.c example.
194 */
195static bool m48t86_verify_chip(struct platform_device *pdev)
196{
197 unsigned int offset0 = M48T86_NVRAM(M48T86_NVRAM_LEN - 2);
198 unsigned int offset1 = M48T86_NVRAM(M48T86_NVRAM_LEN - 1);
199 unsigned char tmp0, tmp1;
200
201 tmp0 = m48t86_readb(&pdev->dev, offset0);
202 tmp1 = m48t86_readb(&pdev->dev, offset1);
203
204 m48t86_writeb(&pdev->dev, 0x00, offset0);
205 m48t86_writeb(&pdev->dev, 0x55, offset1);
206 if (m48t86_readb(&pdev->dev, offset1) == 0x55) {
207 m48t86_writeb(&pdev->dev, 0xaa, offset1);
208 if (m48t86_readb(&pdev->dev, offset1) == 0xaa &&
209 m48t86_readb(&pdev->dev, offset0) == 0x00) {
210 m48t86_writeb(&pdev->dev, tmp0, offset0);
211 m48t86_writeb(&pdev->dev, tmp1, offset1);
212
213 return true;
214 }
215 }
216 return false;
217}
218
219static int m48t86_rtc_probe(struct platform_device *pdev)
220{
221 struct m48t86_rtc_info *info;
222 unsigned char reg;
223 int err;
224 struct nvmem_config m48t86_nvmem_cfg = {
225 .name = "m48t86_nvram",
226 .word_size = 1,
227 .stride = 1,
228 .size = M48T86_NVRAM_LEN,
229 .reg_read = m48t86_nvram_read,
230 .reg_write = m48t86_nvram_write,
231 .priv = &pdev->dev,
232 };
233
234 info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL);
235 if (!info)
236 return -ENOMEM;
237
238 info->index_reg = devm_platform_ioremap_resource(pdev, 0);
239 if (IS_ERR(info->index_reg))
240 return PTR_ERR(info->index_reg);
241
242 info->data_reg = devm_platform_ioremap_resource(pdev, 1);
243 if (IS_ERR(info->data_reg))
244 return PTR_ERR(info->data_reg);
245
246 dev_set_drvdata(&pdev->dev, info);
247
248 if (!m48t86_verify_chip(pdev)) {
249 dev_info(&pdev->dev, "RTC not present\n");
250 return -ENODEV;
251 }
252
253 info->rtc = devm_rtc_allocate_device(&pdev->dev);
254 if (IS_ERR(info->rtc))
255 return PTR_ERR(info->rtc);
256
257 info->rtc->ops = &m48t86_rtc_ops;
258
259 err = devm_rtc_register_device(info->rtc);
260 if (err)
261 return err;
262
263 devm_rtc_nvmem_register(info->rtc, &m48t86_nvmem_cfg);
264
265 /* read battery status */
266 reg = m48t86_readb(&pdev->dev, M48T86_D);
267 dev_info(&pdev->dev, "battery %s\n",
268 (reg & M48T86_D_VRT) ? "ok" : "exhausted");
269
270 return 0;
271}
272
273static const struct of_device_id m48t86_rtc_of_ids[] = {
274 { .compatible = "st,m48t86" },
275 { /* sentinel */ }
276};
277MODULE_DEVICE_TABLE(of, m48t86_rtc_of_ids);
278
279static struct platform_driver m48t86_rtc_platform_driver = {
280 .driver = {
281 .name = "rtc-m48t86",
282 .of_match_table = m48t86_rtc_of_ids,
283 },
284 .probe = m48t86_rtc_probe,
285};
286
287module_platform_driver(m48t86_rtc_platform_driver);
288
289MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
290MODULE_DESCRIPTION("M48T86 RTC driver");
291MODULE_LICENSE("GPL");
292MODULE_ALIAS("platform:rtc-m48t86");
1/*
2 * ST M48T86 / Dallas DS12887 RTC driver
3 * Copyright (c) 2006 Tower Technologies
4 *
5 * Author: Alessandro Zummo <a.zummo@towertech.it>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 *
11 * This drivers only supports the clock running in BCD and 24H mode.
12 * If it will be ever adapted to binary and 12H mode, care must be taken
13 * to not introduce bugs.
14 */
15
16#include <linux/module.h>
17#include <linux/rtc.h>
18#include <linux/platform_device.h>
19#include <linux/platform_data/rtc-m48t86.h>
20#include <linux/bcd.h>
21
22#define M48T86_REG_SEC 0x00
23#define M48T86_REG_SECALRM 0x01
24#define M48T86_REG_MIN 0x02
25#define M48T86_REG_MINALRM 0x03
26#define M48T86_REG_HOUR 0x04
27#define M48T86_REG_HOURALRM 0x05
28#define M48T86_REG_DOW 0x06 /* 1 = sunday */
29#define M48T86_REG_DOM 0x07
30#define M48T86_REG_MONTH 0x08 /* 1 - 12 */
31#define M48T86_REG_YEAR 0x09 /* 0 - 99 */
32#define M48T86_REG_A 0x0A
33#define M48T86_REG_B 0x0B
34#define M48T86_REG_C 0x0C
35#define M48T86_REG_D 0x0D
36
37#define M48T86_REG_B_H24 (1 << 1)
38#define M48T86_REG_B_DM (1 << 2)
39#define M48T86_REG_B_SET (1 << 7)
40#define M48T86_REG_D_VRT (1 << 7)
41
42static int m48t86_rtc_read_time(struct device *dev, struct rtc_time *tm)
43{
44 unsigned char reg;
45 struct platform_device *pdev = to_platform_device(dev);
46 struct m48t86_ops *ops = dev_get_platdata(&pdev->dev);
47
48 reg = ops->readbyte(M48T86_REG_B);
49
50 if (reg & M48T86_REG_B_DM) {
51 /* data (binary) mode */
52 tm->tm_sec = ops->readbyte(M48T86_REG_SEC);
53 tm->tm_min = ops->readbyte(M48T86_REG_MIN);
54 tm->tm_hour = ops->readbyte(M48T86_REG_HOUR) & 0x3F;
55 tm->tm_mday = ops->readbyte(M48T86_REG_DOM);
56 /* tm_mon is 0-11 */
57 tm->tm_mon = ops->readbyte(M48T86_REG_MONTH) - 1;
58 tm->tm_year = ops->readbyte(M48T86_REG_YEAR) + 100;
59 tm->tm_wday = ops->readbyte(M48T86_REG_DOW);
60 } else {
61 /* bcd mode */
62 tm->tm_sec = bcd2bin(ops->readbyte(M48T86_REG_SEC));
63 tm->tm_min = bcd2bin(ops->readbyte(M48T86_REG_MIN));
64 tm->tm_hour = bcd2bin(ops->readbyte(M48T86_REG_HOUR) & 0x3F);
65 tm->tm_mday = bcd2bin(ops->readbyte(M48T86_REG_DOM));
66 /* tm_mon is 0-11 */
67 tm->tm_mon = bcd2bin(ops->readbyte(M48T86_REG_MONTH)) - 1;
68 tm->tm_year = bcd2bin(ops->readbyte(M48T86_REG_YEAR)) + 100;
69 tm->tm_wday = bcd2bin(ops->readbyte(M48T86_REG_DOW));
70 }
71
72 /* correct the hour if the clock is in 12h mode */
73 if (!(reg & M48T86_REG_B_H24))
74 if (ops->readbyte(M48T86_REG_HOUR) & 0x80)
75 tm->tm_hour += 12;
76
77 return rtc_valid_tm(tm);
78}
79
80static int m48t86_rtc_set_time(struct device *dev, struct rtc_time *tm)
81{
82 unsigned char reg;
83 struct platform_device *pdev = to_platform_device(dev);
84 struct m48t86_ops *ops = dev_get_platdata(&pdev->dev);
85
86 reg = ops->readbyte(M48T86_REG_B);
87
88 /* update flag and 24h mode */
89 reg |= M48T86_REG_B_SET | M48T86_REG_B_H24;
90 ops->writebyte(reg, M48T86_REG_B);
91
92 if (reg & M48T86_REG_B_DM) {
93 /* data (binary) mode */
94 ops->writebyte(tm->tm_sec, M48T86_REG_SEC);
95 ops->writebyte(tm->tm_min, M48T86_REG_MIN);
96 ops->writebyte(tm->tm_hour, M48T86_REG_HOUR);
97 ops->writebyte(tm->tm_mday, M48T86_REG_DOM);
98 ops->writebyte(tm->tm_mon + 1, M48T86_REG_MONTH);
99 ops->writebyte(tm->tm_year % 100, M48T86_REG_YEAR);
100 ops->writebyte(tm->tm_wday, M48T86_REG_DOW);
101 } else {
102 /* bcd mode */
103 ops->writebyte(bin2bcd(tm->tm_sec), M48T86_REG_SEC);
104 ops->writebyte(bin2bcd(tm->tm_min), M48T86_REG_MIN);
105 ops->writebyte(bin2bcd(tm->tm_hour), M48T86_REG_HOUR);
106 ops->writebyte(bin2bcd(tm->tm_mday), M48T86_REG_DOM);
107 ops->writebyte(bin2bcd(tm->tm_mon + 1), M48T86_REG_MONTH);
108 ops->writebyte(bin2bcd(tm->tm_year % 100), M48T86_REG_YEAR);
109 ops->writebyte(bin2bcd(tm->tm_wday), M48T86_REG_DOW);
110 }
111
112 /* update ended */
113 reg &= ~M48T86_REG_B_SET;
114 ops->writebyte(reg, M48T86_REG_B);
115
116 return 0;
117}
118
119static int m48t86_rtc_proc(struct device *dev, struct seq_file *seq)
120{
121 unsigned char reg;
122 struct platform_device *pdev = to_platform_device(dev);
123 struct m48t86_ops *ops = dev_get_platdata(&pdev->dev);
124
125 reg = ops->readbyte(M48T86_REG_B);
126
127 seq_printf(seq, "mode\t\t: %s\n",
128 (reg & M48T86_REG_B_DM) ? "binary" : "bcd");
129
130 reg = ops->readbyte(M48T86_REG_D);
131
132 seq_printf(seq, "battery\t\t: %s\n",
133 (reg & M48T86_REG_D_VRT) ? "ok" : "exhausted");
134
135 return 0;
136}
137
138static const struct rtc_class_ops m48t86_rtc_ops = {
139 .read_time = m48t86_rtc_read_time,
140 .set_time = m48t86_rtc_set_time,
141 .proc = m48t86_rtc_proc,
142};
143
144static int m48t86_rtc_probe(struct platform_device *dev)
145{
146 unsigned char reg;
147 struct m48t86_ops *ops = dev_get_platdata(&dev->dev);
148 struct rtc_device *rtc;
149
150 rtc = devm_rtc_device_register(&dev->dev, "m48t86",
151 &m48t86_rtc_ops, THIS_MODULE);
152
153 if (IS_ERR(rtc))
154 return PTR_ERR(rtc);
155
156 platform_set_drvdata(dev, rtc);
157
158 /* read battery status */
159 reg = ops->readbyte(M48T86_REG_D);
160 dev_info(&dev->dev, "battery %s\n",
161 (reg & M48T86_REG_D_VRT) ? "ok" : "exhausted");
162
163 return 0;
164}
165
166static struct platform_driver m48t86_rtc_platform_driver = {
167 .driver = {
168 .name = "rtc-m48t86",
169 },
170 .probe = m48t86_rtc_probe,
171};
172
173module_platform_driver(m48t86_rtc_platform_driver);
174
175MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
176MODULE_DESCRIPTION("M48T86 RTC driver");
177MODULE_LICENSE("GPL");
178MODULE_ALIAS("platform:rtc-m48t86");