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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/rtc.h>
15#include <linux/platform_device.h>
16#include <linux/bcd.h>
17#include <linux/io.h>
18
19#define M48T86_SEC 0x00
20#define M48T86_SECALRM 0x01
21#define M48T86_MIN 0x02
22#define M48T86_MINALRM 0x03
23#define M48T86_HOUR 0x04
24#define M48T86_HOURALRM 0x05
25#define M48T86_DOW 0x06 /* 1 = sunday */
26#define M48T86_DOM 0x07
27#define M48T86_MONTH 0x08 /* 1 - 12 */
28#define M48T86_YEAR 0x09 /* 0 - 99 */
29#define M48T86_A 0x0a
30#define M48T86_B 0x0b
31#define M48T86_B_SET BIT(7)
32#define M48T86_B_DM BIT(2)
33#define M48T86_B_H24 BIT(1)
34#define M48T86_C 0x0c
35#define M48T86_D 0x0d
36#define M48T86_D_VRT BIT(7)
37#define M48T86_NVRAM(x) (0x0e + (x))
38#define M48T86_NVRAM_LEN 114
39
40struct m48t86_rtc_info {
41 void __iomem *index_reg;
42 void __iomem *data_reg;
43 struct rtc_device *rtc;
44};
45
46static unsigned char m48t86_readb(struct device *dev, unsigned long addr)
47{
48 struct m48t86_rtc_info *info = dev_get_drvdata(dev);
49 unsigned char value;
50
51 writeb(addr, info->index_reg);
52 value = readb(info->data_reg);
53
54 return value;
55}
56
57static void m48t86_writeb(struct device *dev,
58 unsigned char value, unsigned long addr)
59{
60 struct m48t86_rtc_info *info = dev_get_drvdata(dev);
61
62 writeb(addr, info->index_reg);
63 writeb(value, info->data_reg);
64}
65
66static int m48t86_rtc_read_time(struct device *dev, struct rtc_time *tm)
67{
68 unsigned char reg;
69
70 reg = m48t86_readb(dev, M48T86_B);
71
72 if (reg & M48T86_B_DM) {
73 /* data (binary) mode */
74 tm->tm_sec = m48t86_readb(dev, M48T86_SEC);
75 tm->tm_min = m48t86_readb(dev, M48T86_MIN);
76 tm->tm_hour = m48t86_readb(dev, M48T86_HOUR) & 0x3f;
77 tm->tm_mday = m48t86_readb(dev, M48T86_DOM);
78 /* tm_mon is 0-11 */
79 tm->tm_mon = m48t86_readb(dev, M48T86_MONTH) - 1;
80 tm->tm_year = m48t86_readb(dev, M48T86_YEAR) + 100;
81 tm->tm_wday = m48t86_readb(dev, M48T86_DOW);
82 } else {
83 /* bcd mode */
84 tm->tm_sec = bcd2bin(m48t86_readb(dev, M48T86_SEC));
85 tm->tm_min = bcd2bin(m48t86_readb(dev, M48T86_MIN));
86 tm->tm_hour = bcd2bin(m48t86_readb(dev, M48T86_HOUR) &
87 0x3f);
88 tm->tm_mday = bcd2bin(m48t86_readb(dev, M48T86_DOM));
89 /* tm_mon is 0-11 */
90 tm->tm_mon = bcd2bin(m48t86_readb(dev, M48T86_MONTH)) - 1;
91 tm->tm_year = bcd2bin(m48t86_readb(dev, M48T86_YEAR)) + 100;
92 tm->tm_wday = bcd2bin(m48t86_readb(dev, M48T86_DOW));
93 }
94
95 /* correct the hour if the clock is in 12h mode */
96 if (!(reg & M48T86_B_H24))
97 if (m48t86_readb(dev, M48T86_HOUR) & 0x80)
98 tm->tm_hour += 12;
99
100 return 0;
101}
102
103static int m48t86_rtc_set_time(struct device *dev, struct rtc_time *tm)
104{
105 unsigned char reg;
106
107 reg = m48t86_readb(dev, M48T86_B);
108
109 /* update flag and 24h mode */
110 reg |= M48T86_B_SET | M48T86_B_H24;
111 m48t86_writeb(dev, reg, M48T86_B);
112
113 if (reg & M48T86_B_DM) {
114 /* data (binary) mode */
115 m48t86_writeb(dev, tm->tm_sec, M48T86_SEC);
116 m48t86_writeb(dev, tm->tm_min, M48T86_MIN);
117 m48t86_writeb(dev, tm->tm_hour, M48T86_HOUR);
118 m48t86_writeb(dev, tm->tm_mday, M48T86_DOM);
119 m48t86_writeb(dev, tm->tm_mon + 1, M48T86_MONTH);
120 m48t86_writeb(dev, tm->tm_year % 100, M48T86_YEAR);
121 m48t86_writeb(dev, tm->tm_wday, M48T86_DOW);
122 } else {
123 /* bcd mode */
124 m48t86_writeb(dev, bin2bcd(tm->tm_sec), M48T86_SEC);
125 m48t86_writeb(dev, bin2bcd(tm->tm_min), M48T86_MIN);
126 m48t86_writeb(dev, bin2bcd(tm->tm_hour), M48T86_HOUR);
127 m48t86_writeb(dev, bin2bcd(tm->tm_mday), M48T86_DOM);
128 m48t86_writeb(dev, bin2bcd(tm->tm_mon + 1), M48T86_MONTH);
129 m48t86_writeb(dev, bin2bcd(tm->tm_year % 100), M48T86_YEAR);
130 m48t86_writeb(dev, bin2bcd(tm->tm_wday), M48T86_DOW);
131 }
132
133 /* update ended */
134 reg &= ~M48T86_B_SET;
135 m48t86_writeb(dev, reg, M48T86_B);
136
137 return 0;
138}
139
140static int m48t86_rtc_proc(struct device *dev, struct seq_file *seq)
141{
142 unsigned char reg;
143
144 reg = m48t86_readb(dev, M48T86_B);
145
146 seq_printf(seq, "mode\t\t: %s\n",
147 (reg & M48T86_B_DM) ? "binary" : "bcd");
148
149 reg = m48t86_readb(dev, M48T86_D);
150
151 seq_printf(seq, "battery\t\t: %s\n",
152 (reg & M48T86_D_VRT) ? "ok" : "exhausted");
153
154 return 0;
155}
156
157static const struct rtc_class_ops m48t86_rtc_ops = {
158 .read_time = m48t86_rtc_read_time,
159 .set_time = m48t86_rtc_set_time,
160 .proc = m48t86_rtc_proc,
161};
162
163static int m48t86_nvram_read(void *priv, unsigned int off, void *buf,
164 size_t count)
165{
166 struct device *dev = priv;
167 unsigned int i;
168
169 for (i = 0; i < count; i++)
170 ((u8 *)buf)[i] = m48t86_readb(dev, M48T86_NVRAM(off + i));
171
172 return 0;
173}
174
175static int m48t86_nvram_write(void *priv, unsigned int off, void *buf,
176 size_t count)
177{
178 struct device *dev = priv;
179 unsigned int i;
180
181 for (i = 0; i < count; i++)
182 m48t86_writeb(dev, ((u8 *)buf)[i], M48T86_NVRAM(off + i));
183
184 return 0;
185}
186
187/*
188 * The RTC is an optional feature at purchase time on some Technologic Systems
189 * boards. Verify that it actually exists by checking if the last two bytes
190 * of the NVRAM can be changed.
191 *
192 * This is based on the method used in their rtc7800.c example.
193 */
194static bool m48t86_verify_chip(struct platform_device *pdev)
195{
196 unsigned int offset0 = M48T86_NVRAM(M48T86_NVRAM_LEN - 2);
197 unsigned int offset1 = M48T86_NVRAM(M48T86_NVRAM_LEN - 1);
198 unsigned char tmp0, tmp1;
199
200 tmp0 = m48t86_readb(&pdev->dev, offset0);
201 tmp1 = m48t86_readb(&pdev->dev, offset1);
202
203 m48t86_writeb(&pdev->dev, 0x00, offset0);
204 m48t86_writeb(&pdev->dev, 0x55, offset1);
205 if (m48t86_readb(&pdev->dev, offset1) == 0x55) {
206 m48t86_writeb(&pdev->dev, 0xaa, offset1);
207 if (m48t86_readb(&pdev->dev, offset1) == 0xaa &&
208 m48t86_readb(&pdev->dev, offset0) == 0x00) {
209 m48t86_writeb(&pdev->dev, tmp0, offset0);
210 m48t86_writeb(&pdev->dev, tmp1, offset1);
211
212 return true;
213 }
214 }
215 return false;
216}
217
218static int m48t86_rtc_probe(struct platform_device *pdev)
219{
220 struct m48t86_rtc_info *info;
221 unsigned char reg;
222 int err;
223 struct nvmem_config m48t86_nvmem_cfg = {
224 .name = "m48t86_nvram",
225 .word_size = 1,
226 .stride = 1,
227 .size = M48T86_NVRAM_LEN,
228 .reg_read = m48t86_nvram_read,
229 .reg_write = m48t86_nvram_write,
230 .priv = &pdev->dev,
231 };
232
233 info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL);
234 if (!info)
235 return -ENOMEM;
236
237 info->index_reg = devm_platform_ioremap_resource(pdev, 0);
238 if (IS_ERR(info->index_reg))
239 return PTR_ERR(info->index_reg);
240
241 info->data_reg = devm_platform_ioremap_resource(pdev, 1);
242 if (IS_ERR(info->data_reg))
243 return PTR_ERR(info->data_reg);
244
245 dev_set_drvdata(&pdev->dev, info);
246
247 if (!m48t86_verify_chip(pdev)) {
248 dev_info(&pdev->dev, "RTC not present\n");
249 return -ENODEV;
250 }
251
252 info->rtc = devm_rtc_allocate_device(&pdev->dev);
253 if (IS_ERR(info->rtc))
254 return PTR_ERR(info->rtc);
255
256 info->rtc->ops = &m48t86_rtc_ops;
257
258 err = devm_rtc_register_device(info->rtc);
259 if (err)
260 return err;
261
262 devm_rtc_nvmem_register(info->rtc, &m48t86_nvmem_cfg);
263
264 /* read battery status */
265 reg = m48t86_readb(&pdev->dev, M48T86_D);
266 dev_info(&pdev->dev, "battery %s\n",
267 (reg & M48T86_D_VRT) ? "ok" : "exhausted");
268
269 return 0;
270}
271
272static struct platform_driver m48t86_rtc_platform_driver = {
273 .driver = {
274 .name = "rtc-m48t86",
275 },
276 .probe = m48t86_rtc_probe,
277};
278
279module_platform_driver(m48t86_rtc_platform_driver);
280
281MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
282MODULE_DESCRIPTION("M48T86 RTC driver");
283MODULE_LICENSE("GPL");
284MODULE_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/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
42#define DRV_VERSION "0.1"
43
44
45static int m48t86_rtc_read_time(struct device *dev, struct rtc_time *tm)
46{
47 unsigned char reg;
48 struct platform_device *pdev = to_platform_device(dev);
49 struct m48t86_ops *ops = pdev->dev.platform_data;
50
51 reg = ops->readbyte(M48T86_REG_B);
52
53 if (reg & M48T86_REG_B_DM) {
54 /* data (binary) mode */
55 tm->tm_sec = ops->readbyte(M48T86_REG_SEC);
56 tm->tm_min = ops->readbyte(M48T86_REG_MIN);
57 tm->tm_hour = ops->readbyte(M48T86_REG_HOUR) & 0x3F;
58 tm->tm_mday = ops->readbyte(M48T86_REG_DOM);
59 /* tm_mon is 0-11 */
60 tm->tm_mon = ops->readbyte(M48T86_REG_MONTH) - 1;
61 tm->tm_year = ops->readbyte(M48T86_REG_YEAR) + 100;
62 tm->tm_wday = ops->readbyte(M48T86_REG_DOW);
63 } else {
64 /* bcd mode */
65 tm->tm_sec = bcd2bin(ops->readbyte(M48T86_REG_SEC));
66 tm->tm_min = bcd2bin(ops->readbyte(M48T86_REG_MIN));
67 tm->tm_hour = bcd2bin(ops->readbyte(M48T86_REG_HOUR) & 0x3F);
68 tm->tm_mday = bcd2bin(ops->readbyte(M48T86_REG_DOM));
69 /* tm_mon is 0-11 */
70 tm->tm_mon = bcd2bin(ops->readbyte(M48T86_REG_MONTH)) - 1;
71 tm->tm_year = bcd2bin(ops->readbyte(M48T86_REG_YEAR)) + 100;
72 tm->tm_wday = bcd2bin(ops->readbyte(M48T86_REG_DOW));
73 }
74
75 /* correct the hour if the clock is in 12h mode */
76 if (!(reg & M48T86_REG_B_H24))
77 if (ops->readbyte(M48T86_REG_HOUR) & 0x80)
78 tm->tm_hour += 12;
79
80 return rtc_valid_tm(tm);
81}
82
83static int m48t86_rtc_set_time(struct device *dev, struct rtc_time *tm)
84{
85 unsigned char reg;
86 struct platform_device *pdev = to_platform_device(dev);
87 struct m48t86_ops *ops = pdev->dev.platform_data;
88
89 reg = ops->readbyte(M48T86_REG_B);
90
91 /* update flag and 24h mode */
92 reg |= M48T86_REG_B_SET | M48T86_REG_B_H24;
93 ops->writebyte(reg, M48T86_REG_B);
94
95 if (reg & M48T86_REG_B_DM) {
96 /* data (binary) mode */
97 ops->writebyte(tm->tm_sec, M48T86_REG_SEC);
98 ops->writebyte(tm->tm_min, M48T86_REG_MIN);
99 ops->writebyte(tm->tm_hour, M48T86_REG_HOUR);
100 ops->writebyte(tm->tm_mday, M48T86_REG_DOM);
101 ops->writebyte(tm->tm_mon + 1, M48T86_REG_MONTH);
102 ops->writebyte(tm->tm_year % 100, M48T86_REG_YEAR);
103 ops->writebyte(tm->tm_wday, M48T86_REG_DOW);
104 } else {
105 /* bcd mode */
106 ops->writebyte(bin2bcd(tm->tm_sec), M48T86_REG_SEC);
107 ops->writebyte(bin2bcd(tm->tm_min), M48T86_REG_MIN);
108 ops->writebyte(bin2bcd(tm->tm_hour), M48T86_REG_HOUR);
109 ops->writebyte(bin2bcd(tm->tm_mday), M48T86_REG_DOM);
110 ops->writebyte(bin2bcd(tm->tm_mon + 1), M48T86_REG_MONTH);
111 ops->writebyte(bin2bcd(tm->tm_year % 100), M48T86_REG_YEAR);
112 ops->writebyte(bin2bcd(tm->tm_wday), M48T86_REG_DOW);
113 }
114
115 /* update ended */
116 reg &= ~M48T86_REG_B_SET;
117 ops->writebyte(reg, M48T86_REG_B);
118
119 return 0;
120}
121
122static int m48t86_rtc_proc(struct device *dev, struct seq_file *seq)
123{
124 unsigned char reg;
125 struct platform_device *pdev = to_platform_device(dev);
126 struct m48t86_ops *ops = pdev->dev.platform_data;
127
128 reg = ops->readbyte(M48T86_REG_B);
129
130 seq_printf(seq, "mode\t\t: %s\n",
131 (reg & M48T86_REG_B_DM) ? "binary" : "bcd");
132
133 reg = ops->readbyte(M48T86_REG_D);
134
135 seq_printf(seq, "battery\t\t: %s\n",
136 (reg & M48T86_REG_D_VRT) ? "ok" : "exhausted");
137
138 return 0;
139}
140
141static const struct rtc_class_ops m48t86_rtc_ops = {
142 .read_time = m48t86_rtc_read_time,
143 .set_time = m48t86_rtc_set_time,
144 .proc = m48t86_rtc_proc,
145};
146
147static int __devinit m48t86_rtc_probe(struct platform_device *dev)
148{
149 unsigned char reg;
150 struct m48t86_ops *ops = dev->dev.platform_data;
151 struct rtc_device *rtc = rtc_device_register("m48t86",
152 &dev->dev, &m48t86_rtc_ops, THIS_MODULE);
153
154 if (IS_ERR(rtc))
155 return PTR_ERR(rtc);
156
157 platform_set_drvdata(dev, rtc);
158
159 /* read battery status */
160 reg = ops->readbyte(M48T86_REG_D);
161 dev_info(&dev->dev, "battery %s\n",
162 (reg & M48T86_REG_D_VRT) ? "ok" : "exhausted");
163
164 return 0;
165}
166
167static int __devexit m48t86_rtc_remove(struct platform_device *dev)
168{
169 struct rtc_device *rtc = platform_get_drvdata(dev);
170
171 if (rtc)
172 rtc_device_unregister(rtc);
173
174 platform_set_drvdata(dev, NULL);
175
176 return 0;
177}
178
179static struct platform_driver m48t86_rtc_platform_driver = {
180 .driver = {
181 .name = "rtc-m48t86",
182 .owner = THIS_MODULE,
183 },
184 .probe = m48t86_rtc_probe,
185 .remove = __devexit_p(m48t86_rtc_remove),
186};
187
188static int __init m48t86_rtc_init(void)
189{
190 return platform_driver_register(&m48t86_rtc_platform_driver);
191}
192
193static void __exit m48t86_rtc_exit(void)
194{
195 platform_driver_unregister(&m48t86_rtc_platform_driver);
196}
197
198MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
199MODULE_DESCRIPTION("M48T86 RTC driver");
200MODULE_LICENSE("GPL");
201MODULE_VERSION(DRV_VERSION);
202MODULE_ALIAS("platform:rtc-m48t86");
203
204module_init(m48t86_rtc_init);
205module_exit(m48t86_rtc_exit);