1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * An rtc/i2c driver for the Dallas DS1672 4 * Copyright 2005-06 Tower Technologies 5 * 6 * Author: Alessandro Zummo <a.zummo@towertech.it> 7 */ 8 9 #include <linux/i2c.h> 10 #include <linux/rtc.h> 11 #include <linux/module.h> 12 13 /* Registers */ 14 15 #define DS1672_REG_CNT_BASE 0 16 #define DS1672_REG_CONTROL 4 17 #define DS1672_REG_TRICKLE 5 18 19 #define DS1672_REG_CONTROL_EOSC 0x80 20 21 /* 22 * In the routines that deal directly with the ds1672 hardware, we use 23 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch 24 * Time is set to UTC. 25 */ 26 static int ds1672_read_time(struct device *dev, struct rtc_time *tm) 27 { 28 struct i2c_client *client = to_i2c_client(dev); 29 unsigned long time; 30 unsigned char addr = DS1672_REG_CONTROL; 31 unsigned char buf[4]; 32 33 struct i2c_msg msgs[] = { 34 {/* setup read ptr */ 35 .addr = client->addr, 36 .len = 1, 37 .buf = &addr 38 }, 39 {/* read date */ 40 .addr = client->addr, 41 .flags = I2C_M_RD, 42 .len = 1, 43 .buf = buf 44 }, 45 }; 46 47 /* read control register */ 48 if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) { 49 dev_warn(&client->dev, "Unable to read the control register\n"); 50 return -EIO; 51 } 52 53 if (buf[0] & DS1672_REG_CONTROL_EOSC) { 54 dev_warn(&client->dev, "Oscillator not enabled. Set time to enable.\n"); 55 return -EINVAL; 56 } 57 58 addr = DS1672_REG_CNT_BASE; 59 msgs[1].len = 4; 60 61 /* read date registers */ 62 if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) { 63 dev_err(&client->dev, "%s: read error\n", __func__); 64 return -EIO; 65 } 66 67 dev_dbg(&client->dev, 68 "%s: raw read data - counters=%02x,%02x,%02x,%02x\n", 69 __func__, buf[0], buf[1], buf[2], buf[3]); 70 71 time = ((unsigned long)buf[3] << 24) | (buf[2] << 16) | 72 (buf[1] << 8) | buf[0]; 73 74 rtc_time64_to_tm(time, tm); 75 76 dev_dbg(&client->dev, "%s: tm is %ptR\n", __func__, tm); 77 78 return 0; 79 } 80 81 static int ds1672_set_time(struct device *dev, struct rtc_time *tm) 82 { 83 struct i2c_client *client = to_i2c_client(dev); 84 int xfer; 85 unsigned char buf[6]; 86 unsigned long secs = rtc_tm_to_time64(tm); 87 88 buf[0] = DS1672_REG_CNT_BASE; 89 buf[1] = secs & 0x000000FF; 90 buf[2] = (secs & 0x0000FF00) >> 8; 91 buf[3] = (secs & 0x00FF0000) >> 16; 92 buf[4] = (secs & 0xFF000000) >> 24; 93 buf[5] = 0; /* set control reg to enable counting */ 94 95 xfer = i2c_master_send(client, buf, 6); 96 if (xfer != 6) { 97 dev_err(&client->dev, "%s: send: %d\n", __func__, xfer); 98 return -EIO; 99 } 100 101 return 0; 102 } 103 104 static const struct rtc_class_ops ds1672_rtc_ops = { 105 .read_time = ds1672_read_time, 106 .set_time = ds1672_set_time, 107 }; 108 109 static int ds1672_probe(struct i2c_client *client, 110 const struct i2c_device_id *id) 111 { 112 int err = 0; 113 struct rtc_device *rtc; 114 115 dev_dbg(&client->dev, "%s\n", __func__); 116 117 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) 118 return -ENODEV; 119 120 rtc = devm_rtc_allocate_device(&client->dev); 121 if (IS_ERR(rtc)) 122 return PTR_ERR(rtc); 123 124 rtc->ops = &ds1672_rtc_ops; 125 rtc->range_max = U32_MAX; 126 127 err = rtc_register_device(rtc); 128 if (err) 129 return err; 130 131 i2c_set_clientdata(client, rtc); 132 133 return 0; 134 } 135 136 static const struct i2c_device_id ds1672_id[] = { 137 { "ds1672", 0 }, 138 { } 139 }; 140 MODULE_DEVICE_TABLE(i2c, ds1672_id); 141 142 static const struct of_device_id ds1672_of_match[] = { 143 { .compatible = "dallas,ds1672" }, 144 { } 145 }; 146 MODULE_DEVICE_TABLE(of, ds1672_of_match); 147 148 static struct i2c_driver ds1672_driver = { 149 .driver = { 150 .name = "rtc-ds1672", 151 .of_match_table = of_match_ptr(ds1672_of_match), 152 }, 153 .probe = &ds1672_probe, 154 .id_table = ds1672_id, 155 }; 156 157 module_i2c_driver(ds1672_driver); 158 159 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>"); 160 MODULE_DESCRIPTION("Dallas/Maxim DS1672 timekeeper driver"); 161 MODULE_LICENSE("GPL"); 162