1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * A SPI driver for the Ricoh RS5C348 RTC
4 *
5 * Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
6 *
7 * The board specific init code should provide characteristics of this
8 * device:
9 * Mode 1 (High-Active, Shift-Then-Sample), High Avtive CS
10 */
11
12 #include <linux/bcd.h>
13 #include <linux/delay.h>
14 #include <linux/device.h>
15 #include <linux/errno.h>
16 #include <linux/init.h>
17 #include <linux/kernel.h>
18 #include <linux/string.h>
19 #include <linux/slab.h>
20 #include <linux/rtc.h>
21 #include <linux/workqueue.h>
22 #include <linux/spi/spi.h>
23 #include <linux/module.h>
24
25 #define RS5C348_REG_SECS 0
26 #define RS5C348_REG_MINS 1
27 #define RS5C348_REG_HOURS 2
28 #define RS5C348_REG_WDAY 3
29 #define RS5C348_REG_DAY 4
30 #define RS5C348_REG_MONTH 5
31 #define RS5C348_REG_YEAR 6
32 #define RS5C348_REG_CTL1 14
33 #define RS5C348_REG_CTL2 15
34
35 #define RS5C348_SECS_MASK 0x7f
36 #define RS5C348_MINS_MASK 0x7f
37 #define RS5C348_HOURS_MASK 0x3f
38 #define RS5C348_WDAY_MASK 0x03
39 #define RS5C348_DAY_MASK 0x3f
40 #define RS5C348_MONTH_MASK 0x1f
41
42 #define RS5C348_BIT_PM 0x20 /* REG_HOURS */
43 #define RS5C348_BIT_Y2K 0x80 /* REG_MONTH */
44 #define RS5C348_BIT_24H 0x20 /* REG_CTL1 */
45 #define RS5C348_BIT_XSTP 0x10 /* REG_CTL2 */
46 #define RS5C348_BIT_VDET 0x40 /* REG_CTL2 */
47
48 #define RS5C348_CMD_W(addr) (((addr) << 4) | 0x08) /* single write */
49 #define RS5C348_CMD_R(addr) (((addr) << 4) | 0x0c) /* single read */
50 #define RS5C348_CMD_MW(addr) (((addr) << 4) | 0x00) /* burst write */
51 #define RS5C348_CMD_MR(addr) (((addr) << 4) | 0x04) /* burst read */
52
53 struct rs5c348_plat_data {
54 struct rtc_device *rtc;
55 int rtc_24h;
56 };
57
58 static int
rs5c348_rtc_set_time(struct device * dev,struct rtc_time * tm)59 rs5c348_rtc_set_time(struct device *dev, struct rtc_time *tm)
60 {
61 struct spi_device *spi = to_spi_device(dev);
62 struct rs5c348_plat_data *pdata = dev_get_platdata(&spi->dev);
63 u8 txbuf[5+7], *txp;
64 int ret;
65
66 ret = spi_w8r8(spi, RS5C348_CMD_R(RS5C348_REG_CTL2));
67 if (ret < 0)
68 return ret;
69 if (ret & RS5C348_BIT_XSTP) {
70 txbuf[0] = RS5C348_CMD_W(RS5C348_REG_CTL2);
71 txbuf[1] = 0;
72 ret = spi_write_then_read(spi, txbuf, 2, NULL, 0);
73 if (ret < 0)
74 return ret;
75 }
76
77 /* Transfer 5 bytes before writing SEC. This gives 31us for carry. */
78 txp = txbuf;
79 txbuf[0] = RS5C348_CMD_R(RS5C348_REG_CTL2); /* cmd, ctl2 */
80 txbuf[1] = 0; /* dummy */
81 txbuf[2] = RS5C348_CMD_R(RS5C348_REG_CTL2); /* cmd, ctl2 */
82 txbuf[3] = 0; /* dummy */
83 txbuf[4] = RS5C348_CMD_MW(RS5C348_REG_SECS); /* cmd, sec, ... */
84 txp = &txbuf[5];
85 txp[RS5C348_REG_SECS] = bin2bcd(tm->tm_sec);
86 txp[RS5C348_REG_MINS] = bin2bcd(tm->tm_min);
87 if (pdata->rtc_24h) {
88 txp[RS5C348_REG_HOURS] = bin2bcd(tm->tm_hour);
89 } else {
90 /* hour 0 is AM12, noon is PM12 */
91 txp[RS5C348_REG_HOURS] = bin2bcd((tm->tm_hour + 11) % 12 + 1) |
92 (tm->tm_hour >= 12 ? RS5C348_BIT_PM : 0);
93 }
94 txp[RS5C348_REG_WDAY] = bin2bcd(tm->tm_wday);
95 txp[RS5C348_REG_DAY] = bin2bcd(tm->tm_mday);
96 txp[RS5C348_REG_MONTH] = bin2bcd(tm->tm_mon + 1) |
97 (tm->tm_year >= 100 ? RS5C348_BIT_Y2K : 0);
98 txp[RS5C348_REG_YEAR] = bin2bcd(tm->tm_year % 100);
99 /* write in one transfer to avoid data inconsistency */
100 ret = spi_write_then_read(spi, txbuf, sizeof(txbuf), NULL, 0);
101 udelay(62); /* Tcsr 62us */
102 return ret;
103 }
104
105 static int
rs5c348_rtc_read_time(struct device * dev,struct rtc_time * tm)106 rs5c348_rtc_read_time(struct device *dev, struct rtc_time *tm)
107 {
108 struct spi_device *spi = to_spi_device(dev);
109 struct rs5c348_plat_data *pdata = dev_get_platdata(&spi->dev);
110 u8 txbuf[5], rxbuf[7];
111 int ret;
112
113 ret = spi_w8r8(spi, RS5C348_CMD_R(RS5C348_REG_CTL2));
114 if (ret < 0)
115 return ret;
116 if (ret & RS5C348_BIT_VDET)
117 dev_warn(&spi->dev, "voltage-low detected.\n");
118 if (ret & RS5C348_BIT_XSTP) {
119 dev_warn(&spi->dev, "oscillator-stop detected.\n");
120 return -EINVAL;
121 }
122
123 /* Transfer 5 byte befores reading SEC. This gives 31us for carry. */
124 txbuf[0] = RS5C348_CMD_R(RS5C348_REG_CTL2); /* cmd, ctl2 */
125 txbuf[1] = 0; /* dummy */
126 txbuf[2] = RS5C348_CMD_R(RS5C348_REG_CTL2); /* cmd, ctl2 */
127 txbuf[3] = 0; /* dummy */
128 txbuf[4] = RS5C348_CMD_MR(RS5C348_REG_SECS); /* cmd, sec, ... */
129
130 /* read in one transfer to avoid data inconsistency */
131 ret = spi_write_then_read(spi, txbuf, sizeof(txbuf),
132 rxbuf, sizeof(rxbuf));
133 udelay(62); /* Tcsr 62us */
134 if (ret < 0)
135 return ret;
136
137 tm->tm_sec = bcd2bin(rxbuf[RS5C348_REG_SECS] & RS5C348_SECS_MASK);
138 tm->tm_min = bcd2bin(rxbuf[RS5C348_REG_MINS] & RS5C348_MINS_MASK);
139 tm->tm_hour = bcd2bin(rxbuf[RS5C348_REG_HOURS] & RS5C348_HOURS_MASK);
140 if (!pdata->rtc_24h) {
141 if (rxbuf[RS5C348_REG_HOURS] & RS5C348_BIT_PM) {
142 tm->tm_hour -= 20;
143 tm->tm_hour %= 12;
144 tm->tm_hour += 12;
145 } else
146 tm->tm_hour %= 12;
147 }
148 tm->tm_wday = bcd2bin(rxbuf[RS5C348_REG_WDAY] & RS5C348_WDAY_MASK);
149 tm->tm_mday = bcd2bin(rxbuf[RS5C348_REG_DAY] & RS5C348_DAY_MASK);
150 tm->tm_mon =
151 bcd2bin(rxbuf[RS5C348_REG_MONTH] & RS5C348_MONTH_MASK) - 1;
152 /* year is 1900 + tm->tm_year */
153 tm->tm_year = bcd2bin(rxbuf[RS5C348_REG_YEAR]) +
154 ((rxbuf[RS5C348_REG_MONTH] & RS5C348_BIT_Y2K) ? 100 : 0);
155
156 return 0;
157 }
158
159 static const struct rtc_class_ops rs5c348_rtc_ops = {
160 .read_time = rs5c348_rtc_read_time,
161 .set_time = rs5c348_rtc_set_time,
162 };
163
rs5c348_probe(struct spi_device * spi)164 static int rs5c348_probe(struct spi_device *spi)
165 {
166 int ret;
167 struct rtc_device *rtc;
168 struct rs5c348_plat_data *pdata;
169
170 pdata = devm_kzalloc(&spi->dev, sizeof(struct rs5c348_plat_data),
171 GFP_KERNEL);
172 if (!pdata)
173 return -ENOMEM;
174 spi->dev.platform_data = pdata;
175
176 /* Check D7 of SECOND register */
177 ret = spi_w8r8(spi, RS5C348_CMD_R(RS5C348_REG_SECS));
178 if (ret < 0 || (ret & 0x80)) {
179 dev_err(&spi->dev, "not found.\n");
180 return ret;
181 }
182
183 dev_info(&spi->dev, "spiclk %u KHz.\n",
184 (spi->max_speed_hz + 500) / 1000);
185
186 ret = spi_w8r8(spi, RS5C348_CMD_R(RS5C348_REG_CTL1));
187 if (ret < 0)
188 return ret;
189 if (ret & RS5C348_BIT_24H)
190 pdata->rtc_24h = 1;
191
192 rtc = devm_rtc_allocate_device(&spi->dev);
193 if (IS_ERR(rtc))
194 return PTR_ERR(rtc);
195
196 pdata->rtc = rtc;
197
198 rtc->ops = &rs5c348_rtc_ops;
199
200 return devm_rtc_register_device(rtc);
201 }
202
203 static struct spi_driver rs5c348_driver = {
204 .driver = {
205 .name = "rtc-rs5c348",
206 },
207 .probe = rs5c348_probe,
208 };
209
210 module_spi_driver(rs5c348_driver);
211
212 MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
213 MODULE_DESCRIPTION("Ricoh RS5C348 RTC driver");
214 MODULE_LICENSE("GPL");
215 MODULE_ALIAS("spi:rtc-rs5c348");
216