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 = ((unsigned long)buf[3] << 24) | (buf[2] << 16) | 62 (buf[1] << 8) | buf[0]; 63 64 rtc_time_to_tm(time, tm); 65 66 dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, " 67 "mday=%d, mon=%d, year=%d, wday=%d\n", 68 __func__, tm->tm_sec, tm->tm_min, tm->tm_hour, 69 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday); 70 71 return 0; 72 } 73 74 static int ds1672_set_mmss(struct i2c_client *client, unsigned long secs) 75 { 76 int xfer; 77 unsigned char buf[6]; 78 79 buf[0] = DS1672_REG_CNT_BASE; 80 buf[1] = secs & 0x000000FF; 81 buf[2] = (secs & 0x0000FF00) >> 8; 82 buf[3] = (secs & 0x00FF0000) >> 16; 83 buf[4] = (secs & 0xFF000000) >> 24; 84 buf[5] = 0; /* set control reg to enable counting */ 85 86 xfer = i2c_master_send(client, buf, 6); 87 if (xfer != 6) { 88 dev_err(&client->dev, "%s: send: %d\n", __func__, xfer); 89 return -EIO; 90 } 91 92 return 0; 93 } 94 95 static int ds1672_rtc_read_time(struct device *dev, struct rtc_time *tm) 96 { 97 return ds1672_get_datetime(to_i2c_client(dev), tm); 98 } 99 100 static int ds1672_rtc_set_mmss(struct device *dev, unsigned long secs) 101 { 102 return ds1672_set_mmss(to_i2c_client(dev), secs); 103 } 104 105 static int ds1672_get_control(struct i2c_client *client, u8 *status) 106 { 107 unsigned char addr = DS1672_REG_CONTROL; 108 109 struct i2c_msg msgs[] = { 110 {/* setup read ptr */ 111 .addr = client->addr, 112 .len = 1, 113 .buf = &addr 114 }, 115 {/* read control */ 116 .addr = client->addr, 117 .flags = I2C_M_RD, 118 .len = 1, 119 .buf = status 120 }, 121 }; 122 123 /* read control register */ 124 if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) { 125 dev_err(&client->dev, "%s: read error\n", __func__); 126 return -EIO; 127 } 128 129 return 0; 130 } 131 132 /* following are the sysfs callback functions */ 133 static ssize_t show_control(struct device *dev, struct device_attribute *attr, 134 char *buf) 135 { 136 struct i2c_client *client = to_i2c_client(dev); 137 u8 control; 138 int err; 139 140 err = ds1672_get_control(client, &control); 141 if (err) 142 return err; 143 144 return sprintf(buf, "%s\n", (control & DS1672_REG_CONTROL_EOSC) 145 ? "disabled" : "enabled"); 146 } 147 148 static DEVICE_ATTR(control, S_IRUGO, show_control, NULL); 149 150 static const struct rtc_class_ops ds1672_rtc_ops = { 151 .read_time = ds1672_rtc_read_time, 152 .set_mmss = ds1672_rtc_set_mmss, 153 }; 154 155 static int ds1672_probe(struct i2c_client *client, 156 const struct i2c_device_id *id) 157 { 158 int err = 0; 159 u8 control; 160 struct rtc_device *rtc; 161 162 dev_dbg(&client->dev, "%s\n", __func__); 163 164 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) 165 return -ENODEV; 166 167 rtc = devm_rtc_device_register(&client->dev, ds1672_driver.driver.name, 168 &ds1672_rtc_ops, THIS_MODULE); 169 170 if (IS_ERR(rtc)) 171 return PTR_ERR(rtc); 172 173 i2c_set_clientdata(client, rtc); 174 175 /* read control register */ 176 err = ds1672_get_control(client, &control); 177 if (err) { 178 dev_warn(&client->dev, "Unable to read the control register\n"); 179 } 180 181 if (control & DS1672_REG_CONTROL_EOSC) 182 dev_warn(&client->dev, "Oscillator not enabled. " 183 "Set time to enable.\n"); 184 185 /* Register sysfs hooks */ 186 err = device_create_file(&client->dev, &dev_attr_control); 187 if (err) 188 dev_err(&client->dev, "Unable to create sysfs entry: %s\n", 189 dev_attr_control.attr.name); 190 191 return 0; 192 } 193 194 static const struct i2c_device_id ds1672_id[] = { 195 { "ds1672", 0 }, 196 { } 197 }; 198 MODULE_DEVICE_TABLE(i2c, ds1672_id); 199 200 static const struct of_device_id ds1672_of_match[] = { 201 { .compatible = "dallas,ds1672" }, 202 { } 203 }; 204 MODULE_DEVICE_TABLE(of, ds1672_of_match); 205 206 static struct i2c_driver ds1672_driver = { 207 .driver = { 208 .name = "rtc-ds1672", 209 .of_match_table = of_match_ptr(ds1672_of_match), 210 }, 211 .probe = &ds1672_probe, 212 .id_table = ds1672_id, 213 }; 214 215 module_i2c_driver(ds1672_driver); 216 217 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>"); 218 MODULE_DESCRIPTION("Dallas/Maxim DS1672 timekeeper driver"); 219 MODULE_LICENSE("GPL"); 220