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 #define DRV_VERSION "0.4" 17 18 /* Registers */ 19 20 #define DS1672_REG_CNT_BASE 0 21 #define DS1672_REG_CONTROL 4 22 #define DS1672_REG_TRICKLE 5 23 24 #define DS1672_REG_CONTROL_EOSC 0x80 25 26 static struct i2c_driver ds1672_driver; 27 28 /* 29 * In the routines that deal directly with the ds1672 hardware, we use 30 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch 31 * Epoch is initialized as 2000. Time is set to UTC. 32 */ 33 static int ds1672_get_datetime(struct i2c_client *client, struct rtc_time *tm) 34 { 35 unsigned long time; 36 unsigned char addr = DS1672_REG_CNT_BASE; 37 unsigned char buf[4]; 38 39 struct i2c_msg msgs[] = { 40 {/* setup read ptr */ 41 .addr = client->addr, 42 .len = 1, 43 .buf = &addr 44 }, 45 {/* read date */ 46 .addr = client->addr, 47 .flags = I2C_M_RD, 48 .len = 4, 49 .buf = buf 50 }, 51 }; 52 53 /* read date registers */ 54 if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) { 55 dev_err(&client->dev, "%s: read error\n", __func__); 56 return -EIO; 57 } 58 59 dev_dbg(&client->dev, 60 "%s: raw read data - counters=%02x,%02x,%02x,%02x\n", 61 __func__, buf[0], buf[1], buf[2], buf[3]); 62 63 time = (buf[3] << 24) | (buf[2] << 16) | (buf[1] << 8) | buf[0]; 64 65 rtc_time_to_tm(time, tm); 66 67 dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, " 68 "mday=%d, mon=%d, year=%d, wday=%d\n", 69 __func__, tm->tm_sec, tm->tm_min, tm->tm_hour, 70 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday); 71 72 return 0; 73 } 74 75 static int ds1672_set_mmss(struct i2c_client *client, unsigned long secs) 76 { 77 int xfer; 78 unsigned char buf[6]; 79 80 buf[0] = DS1672_REG_CNT_BASE; 81 buf[1] = secs & 0x000000FF; 82 buf[2] = (secs & 0x0000FF00) >> 8; 83 buf[3] = (secs & 0x00FF0000) >> 16; 84 buf[4] = (secs & 0xFF000000) >> 24; 85 buf[5] = 0; /* set control reg to enable counting */ 86 87 xfer = i2c_master_send(client, buf, 6); 88 if (xfer != 6) { 89 dev_err(&client->dev, "%s: send: %d\n", __func__, xfer); 90 return -EIO; 91 } 92 93 return 0; 94 } 95 96 static int ds1672_rtc_read_time(struct device *dev, struct rtc_time *tm) 97 { 98 return ds1672_get_datetime(to_i2c_client(dev), tm); 99 } 100 101 static int ds1672_rtc_set_mmss(struct device *dev, unsigned long secs) 102 { 103 return ds1672_set_mmss(to_i2c_client(dev), secs); 104 } 105 106 static int ds1672_get_control(struct i2c_client *client, u8 *status) 107 { 108 unsigned char addr = DS1672_REG_CONTROL; 109 110 struct i2c_msg msgs[] = { 111 {/* setup read ptr */ 112 .addr = client->addr, 113 .len = 1, 114 .buf = &addr 115 }, 116 {/* read control */ 117 .addr = client->addr, 118 .flags = I2C_M_RD, 119 .len = 1, 120 .buf = status 121 }, 122 }; 123 124 /* read control register */ 125 if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) { 126 dev_err(&client->dev, "%s: read error\n", __func__); 127 return -EIO; 128 } 129 130 return 0; 131 } 132 133 /* following are the sysfs callback functions */ 134 static ssize_t show_control(struct device *dev, struct device_attribute *attr, 135 char *buf) 136 { 137 struct i2c_client *client = to_i2c_client(dev); 138 u8 control; 139 int err; 140 141 err = ds1672_get_control(client, &control); 142 if (err) 143 return err; 144 145 return sprintf(buf, "%s\n", (control & DS1672_REG_CONTROL_EOSC) 146 ? "disabled" : "enabled"); 147 } 148 149 static DEVICE_ATTR(control, S_IRUGO, show_control, NULL); 150 151 static const struct rtc_class_ops ds1672_rtc_ops = { 152 .read_time = ds1672_rtc_read_time, 153 .set_mmss = ds1672_rtc_set_mmss, 154 }; 155 156 static int ds1672_probe(struct i2c_client *client, 157 const struct i2c_device_id *id) 158 { 159 int err = 0; 160 u8 control; 161 struct rtc_device *rtc; 162 163 dev_dbg(&client->dev, "%s\n", __func__); 164 165 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) 166 return -ENODEV; 167 168 dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n"); 169 170 rtc = devm_rtc_device_register(&client->dev, ds1672_driver.driver.name, 171 &ds1672_rtc_ops, THIS_MODULE); 172 173 if (IS_ERR(rtc)) 174 return PTR_ERR(rtc); 175 176 i2c_set_clientdata(client, rtc); 177 178 /* read control register */ 179 err = ds1672_get_control(client, &control); 180 if (err) { 181 dev_warn(&client->dev, "Unable to read the control register\n"); 182 } 183 184 if (control & DS1672_REG_CONTROL_EOSC) 185 dev_warn(&client->dev, "Oscillator not enabled. " 186 "Set time to enable.\n"); 187 188 /* Register sysfs hooks */ 189 err = device_create_file(&client->dev, &dev_attr_control); 190 if (err) 191 dev_err(&client->dev, "Unable to create sysfs entry: %s\n", 192 dev_attr_control.attr.name); 193 194 return 0; 195 } 196 197 static struct i2c_device_id ds1672_id[] = { 198 { "ds1672", 0 }, 199 { } 200 }; 201 202 static struct i2c_driver ds1672_driver = { 203 .driver = { 204 .name = "rtc-ds1672", 205 }, 206 .probe = &ds1672_probe, 207 .id_table = ds1672_id, 208 }; 209 210 module_i2c_driver(ds1672_driver); 211 212 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>"); 213 MODULE_DESCRIPTION("Dallas/Maxim DS1672 timekeeper driver"); 214 MODULE_LICENSE("GPL"); 215 MODULE_VERSION(DRV_VERSION); 216