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 15 #define DRV_VERSION "0.4" 16 17 /* Registers */ 18 19 #define DS1672_REG_CNT_BASE 0 20 #define DS1672_REG_CONTROL 4 21 #define DS1672_REG_TRICKLE 5 22 23 #define DS1672_REG_CONTROL_EOSC 0x80 24 25 static struct i2c_driver ds1672_driver; 26 27 /* 28 * In the routines that deal directly with the ds1672 hardware, we use 29 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch 30 * Epoch is initialized as 2000. Time is set to UTC. 31 */ 32 static int ds1672_get_datetime(struct i2c_client *client, struct rtc_time *tm) 33 { 34 unsigned long time; 35 unsigned char addr = DS1672_REG_CNT_BASE; 36 unsigned char buf[4]; 37 38 struct i2c_msg msgs[] = { 39 {client->addr, 0, 1, &addr}, /* setup read ptr */ 40 {client->addr, I2C_M_RD, 4, buf}, /* read date */ 41 }; 42 43 /* read date registers */ 44 if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) { 45 dev_err(&client->dev, "%s: read error\n", __func__); 46 return -EIO; 47 } 48 49 dev_dbg(&client->dev, 50 "%s: raw read data - counters=%02x,%02x,%02x,%02x\n", 51 __func__, buf[0], buf[1], buf[2], buf[3]); 52 53 time = (buf[3] << 24) | (buf[2] << 16) | (buf[1] << 8) | buf[0]; 54 55 rtc_time_to_tm(time, tm); 56 57 dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, " 58 "mday=%d, mon=%d, year=%d, wday=%d\n", 59 __func__, tm->tm_sec, tm->tm_min, tm->tm_hour, 60 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday); 61 62 return 0; 63 } 64 65 static int ds1672_set_mmss(struct i2c_client *client, unsigned long secs) 66 { 67 int xfer; 68 unsigned char buf[6]; 69 70 buf[0] = DS1672_REG_CNT_BASE; 71 buf[1] = secs & 0x000000FF; 72 buf[2] = (secs & 0x0000FF00) >> 8; 73 buf[3] = (secs & 0x00FF0000) >> 16; 74 buf[4] = (secs & 0xFF000000) >> 24; 75 buf[5] = 0; /* set control reg to enable counting */ 76 77 xfer = i2c_master_send(client, buf, 6); 78 if (xfer != 6) { 79 dev_err(&client->dev, "%s: send: %d\n", __func__, xfer); 80 return -EIO; 81 } 82 83 return 0; 84 } 85 86 static int ds1672_rtc_read_time(struct device *dev, struct rtc_time *tm) 87 { 88 return ds1672_get_datetime(to_i2c_client(dev), tm); 89 } 90 91 static int ds1672_rtc_set_mmss(struct device *dev, unsigned long secs) 92 { 93 return ds1672_set_mmss(to_i2c_client(dev), secs); 94 } 95 96 static int ds1672_get_control(struct i2c_client *client, u8 *status) 97 { 98 unsigned char addr = DS1672_REG_CONTROL; 99 100 struct i2c_msg msgs[] = { 101 {client->addr, 0, 1, &addr}, /* setup read ptr */ 102 {client->addr, I2C_M_RD, 1, status}, /* read control */ 103 }; 104 105 /* read control register */ 106 if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) { 107 dev_err(&client->dev, "%s: read error\n", __func__); 108 return -EIO; 109 } 110 111 return 0; 112 } 113 114 /* following are the sysfs callback functions */ 115 static ssize_t show_control(struct device *dev, struct device_attribute *attr, 116 char *buf) 117 { 118 struct i2c_client *client = to_i2c_client(dev); 119 u8 control; 120 int err; 121 122 err = ds1672_get_control(client, &control); 123 if (err) 124 return err; 125 126 return sprintf(buf, "%s\n", (control & DS1672_REG_CONTROL_EOSC) 127 ? "disabled" : "enabled"); 128 } 129 130 static DEVICE_ATTR(control, S_IRUGO, show_control, NULL); 131 132 static const struct rtc_class_ops ds1672_rtc_ops = { 133 .read_time = ds1672_rtc_read_time, 134 .set_mmss = ds1672_rtc_set_mmss, 135 }; 136 137 static int ds1672_remove(struct i2c_client *client) 138 { 139 struct rtc_device *rtc = i2c_get_clientdata(client); 140 141 if (rtc) 142 rtc_device_unregister(rtc); 143 144 return 0; 145 } 146 147 static int ds1672_probe(struct i2c_client *client, 148 const struct i2c_device_id *id) 149 { 150 int err = 0; 151 u8 control; 152 struct rtc_device *rtc; 153 154 dev_dbg(&client->dev, "%s\n", __func__); 155 156 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) 157 return -ENODEV; 158 159 dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n"); 160 161 rtc = rtc_device_register(ds1672_driver.driver.name, &client->dev, 162 &ds1672_rtc_ops, THIS_MODULE); 163 164 if (IS_ERR(rtc)) 165 return PTR_ERR(rtc); 166 167 i2c_set_clientdata(client, rtc); 168 169 /* read control register */ 170 err = ds1672_get_control(client, &control); 171 if (err) 172 goto exit_devreg; 173 174 if (control & DS1672_REG_CONTROL_EOSC) 175 dev_warn(&client->dev, "Oscillator not enabled. " 176 "Set time to enable.\n"); 177 178 /* Register sysfs hooks */ 179 err = device_create_file(&client->dev, &dev_attr_control); 180 if (err) 181 goto exit_devreg; 182 183 return 0; 184 185 exit_devreg: 186 rtc_device_unregister(rtc); 187 return err; 188 } 189 190 static struct i2c_device_id ds1672_id[] = { 191 { "ds1672", 0 }, 192 { } 193 }; 194 195 static struct i2c_driver ds1672_driver = { 196 .driver = { 197 .name = "rtc-ds1672", 198 }, 199 .probe = &ds1672_probe, 200 .remove = &ds1672_remove, 201 .id_table = ds1672_id, 202 }; 203 204 static int __init ds1672_init(void) 205 { 206 return i2c_add_driver(&ds1672_driver); 207 } 208 209 static void __exit ds1672_exit(void) 210 { 211 i2c_del_driver(&ds1672_driver); 212 } 213 214 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>"); 215 MODULE_DESCRIPTION("Dallas/Maxim DS1672 timekeeper driver"); 216 MODULE_LICENSE("GPL"); 217 MODULE_VERSION(DRV_VERSION); 218 219 module_init(ds1672_init); 220 module_exit(ds1672_exit); 221