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 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 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 }; 163 164 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 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