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 static struct i2c_driver ds1672_driver; 25 26 /* 27 * In the routines that deal directly with the ds1672 hardware, we use 28 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch 29 * Epoch is initialized as 2000. Time is set to UTC. 30 */ 31 static int ds1672_get_datetime(struct i2c_client *client, struct rtc_time *tm) 32 { 33 unsigned long time; 34 unsigned char addr = DS1672_REG_CNT_BASE; 35 unsigned char buf[4]; 36 37 struct i2c_msg msgs[] = { 38 {/* setup read ptr */ 39 .addr = client->addr, 40 .len = 1, 41 .buf = &addr 42 }, 43 {/* read date */ 44 .addr = client->addr, 45 .flags = I2C_M_RD, 46 .len = 4, 47 .buf = buf 48 }, 49 }; 50 51 /* read date registers */ 52 if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) { 53 dev_err(&client->dev, "%s: read error\n", __func__); 54 return -EIO; 55 } 56 57 dev_dbg(&client->dev, 58 "%s: raw read data - counters=%02x,%02x,%02x,%02x\n", 59 __func__, buf[0], buf[1], buf[2], buf[3]); 60 61 time = (buf[3] << 24) | (buf[2] << 16) | (buf[1] << 8) | buf[0]; 62 63 rtc_time_to_tm(time, tm); 64 65 dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, " 66 "mday=%d, mon=%d, year=%d, wday=%d\n", 67 __func__, tm->tm_sec, tm->tm_min, tm->tm_hour, 68 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday); 69 70 return 0; 71 } 72 73 static int ds1672_set_mmss(struct i2c_client *client, unsigned long secs) 74 { 75 int xfer; 76 unsigned char buf[6]; 77 78 buf[0] = DS1672_REG_CNT_BASE; 79 buf[1] = secs & 0x000000FF; 80 buf[2] = (secs & 0x0000FF00) >> 8; 81 buf[3] = (secs & 0x00FF0000) >> 16; 82 buf[4] = (secs & 0xFF000000) >> 24; 83 buf[5] = 0; /* set control reg to enable counting */ 84 85 xfer = i2c_master_send(client, buf, 6); 86 if (xfer != 6) { 87 dev_err(&client->dev, "%s: send: %d\n", __func__, xfer); 88 return -EIO; 89 } 90 91 return 0; 92 } 93 94 static int ds1672_rtc_read_time(struct device *dev, struct rtc_time *tm) 95 { 96 return ds1672_get_datetime(to_i2c_client(dev), tm); 97 } 98 99 static int ds1672_rtc_set_mmss(struct device *dev, unsigned long secs) 100 { 101 return ds1672_set_mmss(to_i2c_client(dev), secs); 102 } 103 104 static int ds1672_get_control(struct i2c_client *client, u8 *status) 105 { 106 unsigned char addr = DS1672_REG_CONTROL; 107 108 struct i2c_msg msgs[] = { 109 {/* setup read ptr */ 110 .addr = client->addr, 111 .len = 1, 112 .buf = &addr 113 }, 114 {/* read control */ 115 .addr = client->addr, 116 .flags = I2C_M_RD, 117 .len = 1, 118 .buf = status 119 }, 120 }; 121 122 /* read control register */ 123 if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) { 124 dev_err(&client->dev, "%s: read error\n", __func__); 125 return -EIO; 126 } 127 128 return 0; 129 } 130 131 /* following are the sysfs callback functions */ 132 static ssize_t show_control(struct device *dev, struct device_attribute *attr, 133 char *buf) 134 { 135 struct i2c_client *client = to_i2c_client(dev); 136 u8 control; 137 int err; 138 139 err = ds1672_get_control(client, &control); 140 if (err) 141 return err; 142 143 return sprintf(buf, "%s\n", (control & DS1672_REG_CONTROL_EOSC) 144 ? "disabled" : "enabled"); 145 } 146 147 static DEVICE_ATTR(control, S_IRUGO, show_control, NULL); 148 149 static const struct rtc_class_ops ds1672_rtc_ops = { 150 .read_time = ds1672_rtc_read_time, 151 .set_mmss = ds1672_rtc_set_mmss, 152 }; 153 154 static int ds1672_probe(struct i2c_client *client, 155 const struct i2c_device_id *id) 156 { 157 int err = 0; 158 u8 control; 159 struct rtc_device *rtc; 160 161 dev_dbg(&client->dev, "%s\n", __func__); 162 163 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) 164 return -ENODEV; 165 166 rtc = devm_rtc_device_register(&client->dev, ds1672_driver.driver.name, 167 &ds1672_rtc_ops, THIS_MODULE); 168 169 if (IS_ERR(rtc)) 170 return PTR_ERR(rtc); 171 172 i2c_set_clientdata(client, rtc); 173 174 /* read control register */ 175 err = ds1672_get_control(client, &control); 176 if (err) { 177 dev_warn(&client->dev, "Unable to read the control register\n"); 178 } 179 180 if (control & DS1672_REG_CONTROL_EOSC) 181 dev_warn(&client->dev, "Oscillator not enabled. " 182 "Set time to enable.\n"); 183 184 /* Register sysfs hooks */ 185 err = device_create_file(&client->dev, &dev_attr_control); 186 if (err) 187 dev_err(&client->dev, "Unable to create sysfs entry: %s\n", 188 dev_attr_control.attr.name); 189 190 return 0; 191 } 192 193 static struct i2c_device_id ds1672_id[] = { 194 { "ds1672", 0 }, 195 { } 196 }; 197 MODULE_DEVICE_TABLE(i2c, ds1672_id); 198 199 static struct i2c_driver ds1672_driver = { 200 .driver = { 201 .name = "rtc-ds1672", 202 }, 203 .probe = &ds1672_probe, 204 .id_table = ds1672_id, 205 }; 206 207 module_i2c_driver(ds1672_driver); 208 209 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>"); 210 MODULE_DESCRIPTION("Dallas/Maxim DS1672 timekeeper driver"); 211 MODULE_LICENSE("GPL"); 212