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 {client->addr, 0, 1, &addr}, /* setup read ptr */ 41 {client->addr, I2C_M_RD, 4, buf}, /* read date */ 42 }; 43 44 /* read date registers */ 45 if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) { 46 dev_err(&client->dev, "%s: read error\n", __func__); 47 return -EIO; 48 } 49 50 dev_dbg(&client->dev, 51 "%s: raw read data - counters=%02x,%02x,%02x,%02x\n", 52 __func__, buf[0], buf[1], buf[2], buf[3]); 53 54 time = (buf[3] << 24) | (buf[2] << 16) | (buf[1] << 8) | buf[0]; 55 56 rtc_time_to_tm(time, tm); 57 58 dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, " 59 "mday=%d, mon=%d, year=%d, wday=%d\n", 60 __func__, tm->tm_sec, tm->tm_min, tm->tm_hour, 61 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday); 62 63 return 0; 64 } 65 66 static int ds1672_set_mmss(struct i2c_client *client, unsigned long secs) 67 { 68 int xfer; 69 unsigned char buf[6]; 70 71 buf[0] = DS1672_REG_CNT_BASE; 72 buf[1] = secs & 0x000000FF; 73 buf[2] = (secs & 0x0000FF00) >> 8; 74 buf[3] = (secs & 0x00FF0000) >> 16; 75 buf[4] = (secs & 0xFF000000) >> 24; 76 buf[5] = 0; /* set control reg to enable counting */ 77 78 xfer = i2c_master_send(client, buf, 6); 79 if (xfer != 6) { 80 dev_err(&client->dev, "%s: send: %d\n", __func__, xfer); 81 return -EIO; 82 } 83 84 return 0; 85 } 86 87 static int ds1672_rtc_read_time(struct device *dev, struct rtc_time *tm) 88 { 89 return ds1672_get_datetime(to_i2c_client(dev), tm); 90 } 91 92 static int ds1672_rtc_set_mmss(struct device *dev, unsigned long secs) 93 { 94 return ds1672_set_mmss(to_i2c_client(dev), secs); 95 } 96 97 static int ds1672_get_control(struct i2c_client *client, u8 *status) 98 { 99 unsigned char addr = DS1672_REG_CONTROL; 100 101 struct i2c_msg msgs[] = { 102 {client->addr, 0, 1, &addr}, /* setup read ptr */ 103 {client->addr, I2C_M_RD, 1, status}, /* read control */ 104 }; 105 106 /* read control register */ 107 if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) { 108 dev_err(&client->dev, "%s: read error\n", __func__); 109 return -EIO; 110 } 111 112 return 0; 113 } 114 115 /* following are the sysfs callback functions */ 116 static ssize_t show_control(struct device *dev, struct device_attribute *attr, 117 char *buf) 118 { 119 struct i2c_client *client = to_i2c_client(dev); 120 u8 control; 121 int err; 122 123 err = ds1672_get_control(client, &control); 124 if (err) 125 return err; 126 127 return sprintf(buf, "%s\n", (control & DS1672_REG_CONTROL_EOSC) 128 ? "disabled" : "enabled"); 129 } 130 131 static DEVICE_ATTR(control, S_IRUGO, show_control, NULL); 132 133 static const struct rtc_class_ops ds1672_rtc_ops = { 134 .read_time = ds1672_rtc_read_time, 135 .set_mmss = ds1672_rtc_set_mmss, 136 }; 137 138 static int ds1672_remove(struct i2c_client *client) 139 { 140 struct rtc_device *rtc = i2c_get_clientdata(client); 141 142 if (rtc) 143 rtc_device_unregister(rtc); 144 145 return 0; 146 } 147 148 static int ds1672_probe(struct i2c_client *client, 149 const struct i2c_device_id *id) 150 { 151 int err = 0; 152 u8 control; 153 struct rtc_device *rtc; 154 155 dev_dbg(&client->dev, "%s\n", __func__); 156 157 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) 158 return -ENODEV; 159 160 dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n"); 161 162 rtc = rtc_device_register(ds1672_driver.driver.name, &client->dev, 163 &ds1672_rtc_ops, THIS_MODULE); 164 165 if (IS_ERR(rtc)) 166 return PTR_ERR(rtc); 167 168 i2c_set_clientdata(client, rtc); 169 170 /* read control register */ 171 err = ds1672_get_control(client, &control); 172 if (err) 173 goto exit_devreg; 174 175 if (control & DS1672_REG_CONTROL_EOSC) 176 dev_warn(&client->dev, "Oscillator not enabled. " 177 "Set time to enable.\n"); 178 179 /* Register sysfs hooks */ 180 err = device_create_file(&client->dev, &dev_attr_control); 181 if (err) 182 goto exit_devreg; 183 184 return 0; 185 186 exit_devreg: 187 rtc_device_unregister(rtc); 188 return err; 189 } 190 191 static struct i2c_device_id ds1672_id[] = { 192 { "ds1672", 0 }, 193 { } 194 }; 195 196 static struct i2c_driver ds1672_driver = { 197 .driver = { 198 .name = "rtc-ds1672", 199 }, 200 .probe = &ds1672_probe, 201 .remove = &ds1672_remove, 202 .id_table = ds1672_id, 203 }; 204 205 module_i2c_driver(ds1672_driver); 206 207 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>"); 208 MODULE_DESCRIPTION("Dallas/Maxim DS1672 timekeeper driver"); 209 MODULE_LICENSE("GPL"); 210 MODULE_VERSION(DRV_VERSION); 211