1 /* 2 * An rtc/i2c driver for the Dallas DS1672 3 * Copyright 2005-06 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 12 #include <linux/i2c.h> 13 #include <linux/rtc.h> 14 #include <linux/module.h> 15 16 /* Registers */ 17 18 #define DS1672_REG_CNT_BASE 0 19 #define DS1672_REG_CONTROL 4 20 #define DS1672_REG_TRICKLE 5 21 22 #define DS1672_REG_CONTROL_EOSC 0x80 23 24 /* 25 * In the routines that deal directly with the ds1672 hardware, we use 26 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch 27 * Time is set to UTC. 28 */ 29 static int ds1672_read_time(struct device *dev, struct rtc_time *tm) 30 { 31 struct i2c_client *client = to_i2c_client(dev); 32 unsigned long time; 33 unsigned char addr = DS1672_REG_CONTROL; 34 unsigned char buf[4]; 35 36 struct i2c_msg msgs[] = { 37 {/* setup read ptr */ 38 .addr = client->addr, 39 .len = 1, 40 .buf = &addr 41 }, 42 {/* read date */ 43 .addr = client->addr, 44 .flags = I2C_M_RD, 45 .len = 1, 46 .buf = buf 47 }, 48 }; 49 50 /* read control register */ 51 if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) { 52 dev_warn(&client->dev, "Unable to read the control register\n"); 53 return -EIO; 54 } 55 56 if (buf[0] & DS1672_REG_CONTROL_EOSC) { 57 dev_warn(&client->dev, "Oscillator not enabled. Set time to enable.\n"); 58 return -EINVAL; 59 } 60 61 addr = DS1672_REG_CNT_BASE; 62 msgs[1].len = 4; 63 64 /* read date registers */ 65 if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) { 66 dev_err(&client->dev, "%s: read error\n", __func__); 67 return -EIO; 68 } 69 70 dev_dbg(&client->dev, 71 "%s: raw read data - counters=%02x,%02x,%02x,%02x\n", 72 __func__, buf[0], buf[1], buf[2], buf[3]); 73 74 time = ((unsigned long)buf[3] << 24) | (buf[2] << 16) | 75 (buf[1] << 8) | buf[0]; 76 77 rtc_time64_to_tm(time, tm); 78 79 dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, " 80 "mday=%d, mon=%d, year=%d, wday=%d\n", 81 __func__, tm->tm_sec, tm->tm_min, tm->tm_hour, 82 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday); 83 84 return 0; 85 } 86 87 static int ds1672_set_time(struct device *dev, struct rtc_time *tm) 88 { 89 struct i2c_client *client = to_i2c_client(dev); 90 int xfer; 91 unsigned char buf[6]; 92 unsigned long secs = rtc_tm_to_time64(tm); 93 94 buf[0] = DS1672_REG_CNT_BASE; 95 buf[1] = secs & 0x000000FF; 96 buf[2] = (secs & 0x0000FF00) >> 8; 97 buf[3] = (secs & 0x00FF0000) >> 16; 98 buf[4] = (secs & 0xFF000000) >> 24; 99 buf[5] = 0; /* set control reg to enable counting */ 100 101 xfer = i2c_master_send(client, buf, 6); 102 if (xfer != 6) { 103 dev_err(&client->dev, "%s: send: %d\n", __func__, xfer); 104 return -EIO; 105 } 106 107 return 0; 108 } 109 110 static const struct rtc_class_ops ds1672_rtc_ops = { 111 .read_time = ds1672_read_time, 112 .set_time = ds1672_set_time, 113 }; 114 115 static int ds1672_probe(struct i2c_client *client, 116 const struct i2c_device_id *id) 117 { 118 int err = 0; 119 struct rtc_device *rtc; 120 121 dev_dbg(&client->dev, "%s\n", __func__); 122 123 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) 124 return -ENODEV; 125 126 rtc = devm_rtc_allocate_device(&client->dev); 127 if (IS_ERR(rtc)) 128 return PTR_ERR(rtc); 129 130 rtc->ops = &ds1672_rtc_ops; 131 rtc->range_max = U32_MAX; 132 133 err = rtc_register_device(rtc); 134 if (err) 135 return err; 136 137 if (IS_ERR(rtc)) 138 return PTR_ERR(rtc); 139 140 i2c_set_clientdata(client, rtc); 141 142 return 0; 143 } 144 145 static const struct i2c_device_id ds1672_id[] = { 146 { "ds1672", 0 }, 147 { } 148 }; 149 MODULE_DEVICE_TABLE(i2c, ds1672_id); 150 151 static const struct of_device_id ds1672_of_match[] = { 152 { .compatible = "dallas,ds1672" }, 153 { } 154 }; 155 MODULE_DEVICE_TABLE(of, ds1672_of_match); 156 157 static struct i2c_driver ds1672_driver = { 158 .driver = { 159 .name = "rtc-ds1672", 160 .of_match_table = of_match_ptr(ds1672_of_match), 161 }, 162 .probe = &ds1672_probe, 163 .id_table = ds1672_id, 164 }; 165 166 module_i2c_driver(ds1672_driver); 167 168 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>"); 169 MODULE_DESCRIPTION("Dallas/Maxim DS1672 timekeeper driver"); 170 MODULE_LICENSE("GPL"); 171