1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * An rtc/i2c driver for the EM Microelectronic EM3027 4 * Copyright 2011 CompuLab, Ltd. 5 * 6 * Author: Mike Rapoport <mike@compulab.co.il> 7 * 8 * Based on rtc-ds1672.c by Alessandro Zummo <a.zummo@towertech.it> 9 */ 10 11 #include <linux/i2c.h> 12 #include <linux/rtc.h> 13 #include <linux/bcd.h> 14 #include <linux/module.h> 15 #include <linux/of.h> 16 17 /* Registers */ 18 #define EM3027_REG_ON_OFF_CTRL 0x00 19 #define EM3027_REG_IRQ_CTRL 0x01 20 #define EM3027_REG_IRQ_FLAGS 0x02 21 #define EM3027_REG_STATUS 0x03 22 #define EM3027_REG_RST_CTRL 0x04 23 24 #define EM3027_REG_WATCH_SEC 0x08 25 #define EM3027_REG_WATCH_MIN 0x09 26 #define EM3027_REG_WATCH_HOUR 0x0a 27 #define EM3027_REG_WATCH_DATE 0x0b 28 #define EM3027_REG_WATCH_DAY 0x0c 29 #define EM3027_REG_WATCH_MON 0x0d 30 #define EM3027_REG_WATCH_YEAR 0x0e 31 32 #define EM3027_REG_ALARM_SEC 0x10 33 #define EM3027_REG_ALARM_MIN 0x11 34 #define EM3027_REG_ALARM_HOUR 0x12 35 #define EM3027_REG_ALARM_DATE 0x13 36 #define EM3027_REG_ALARM_DAY 0x14 37 #define EM3027_REG_ALARM_MON 0x15 38 #define EM3027_REG_ALARM_YEAR 0x16 39 40 static struct i2c_driver em3027_driver; 41 42 static int em3027_get_time(struct device *dev, struct rtc_time *tm) 43 { 44 struct i2c_client *client = to_i2c_client(dev); 45 46 unsigned char addr = EM3027_REG_WATCH_SEC; 47 unsigned char buf[7]; 48 49 struct i2c_msg msgs[] = { 50 {/* setup read addr */ 51 .addr = client->addr, 52 .len = 1, 53 .buf = &addr 54 }, 55 {/* read time/date */ 56 .addr = client->addr, 57 .flags = I2C_M_RD, 58 .len = 7, 59 .buf = buf 60 }, 61 }; 62 63 /* read time/date registers */ 64 if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) { 65 dev_err(&client->dev, "%s: read error\n", __func__); 66 return -EIO; 67 } 68 69 tm->tm_sec = bcd2bin(buf[0]); 70 tm->tm_min = bcd2bin(buf[1]); 71 tm->tm_hour = bcd2bin(buf[2]); 72 tm->tm_mday = bcd2bin(buf[3]); 73 tm->tm_wday = bcd2bin(buf[4]); 74 tm->tm_mon = bcd2bin(buf[5]) - 1; 75 tm->tm_year = bcd2bin(buf[6]) + 100; 76 77 return 0; 78 } 79 80 static int em3027_set_time(struct device *dev, struct rtc_time *tm) 81 { 82 struct i2c_client *client = to_i2c_client(dev); 83 unsigned char buf[8]; 84 85 struct i2c_msg msg = { 86 .addr = client->addr, 87 .len = 8, 88 .buf = buf, /* write time/date */ 89 }; 90 91 buf[0] = EM3027_REG_WATCH_SEC; 92 buf[1] = bin2bcd(tm->tm_sec); 93 buf[2] = bin2bcd(tm->tm_min); 94 buf[3] = bin2bcd(tm->tm_hour); 95 buf[4] = bin2bcd(tm->tm_mday); 96 buf[5] = bin2bcd(tm->tm_wday); 97 buf[6] = bin2bcd(tm->tm_mon + 1); 98 buf[7] = bin2bcd(tm->tm_year % 100); 99 100 /* write time/date registers */ 101 if ((i2c_transfer(client->adapter, &msg, 1)) != 1) { 102 dev_err(&client->dev, "%s: write error\n", __func__); 103 return -EIO; 104 } 105 106 return 0; 107 } 108 109 static const struct rtc_class_ops em3027_rtc_ops = { 110 .read_time = em3027_get_time, 111 .set_time = em3027_set_time, 112 }; 113 114 static int em3027_probe(struct i2c_client *client) 115 { 116 struct rtc_device *rtc; 117 118 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) 119 return -ENODEV; 120 121 rtc = devm_rtc_device_register(&client->dev, em3027_driver.driver.name, 122 &em3027_rtc_ops, THIS_MODULE); 123 if (IS_ERR(rtc)) 124 return PTR_ERR(rtc); 125 126 i2c_set_clientdata(client, rtc); 127 128 return 0; 129 } 130 131 static const struct i2c_device_id em3027_id[] = { 132 { "em3027", 0 }, 133 { } 134 }; 135 MODULE_DEVICE_TABLE(i2c, em3027_id); 136 137 #ifdef CONFIG_OF 138 static const struct of_device_id em3027_of_match[] = { 139 { .compatible = "emmicro,em3027", }, 140 {} 141 }; 142 MODULE_DEVICE_TABLE(of, em3027_of_match); 143 #endif 144 145 static struct i2c_driver em3027_driver = { 146 .driver = { 147 .name = "rtc-em3027", 148 .of_match_table = of_match_ptr(em3027_of_match), 149 }, 150 .probe = em3027_probe, 151 .id_table = em3027_id, 152 }; 153 154 module_i2c_driver(em3027_driver); 155 156 MODULE_AUTHOR("Mike Rapoport <mike@compulab.co.il>"); 157 MODULE_DESCRIPTION("EM Microelectronic EM3027 RTC driver"); 158 MODULE_LICENSE("GPL"); 159