1 /* 2 * Driver for TI BQ32000 RTC. 3 * 4 * Copyright (C) 2009 Semihalf. 5 * Copyright (C) 2014 Pavel Machek <pavel@denx.de> 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 * You can get hardware description at 12 * http://www.ti.com/lit/ds/symlink/bq32000.pdf 13 */ 14 15 #include <linux/module.h> 16 #include <linux/i2c.h> 17 #include <linux/rtc.h> 18 #include <linux/init.h> 19 #include <linux/errno.h> 20 #include <linux/bcd.h> 21 22 #define BQ32K_SECONDS 0x00 /* Seconds register address */ 23 #define BQ32K_SECONDS_MASK 0x7F /* Mask over seconds value */ 24 #define BQ32K_STOP 0x80 /* Oscillator Stop flat */ 25 26 #define BQ32K_MINUTES 0x01 /* Minutes register address */ 27 #define BQ32K_MINUTES_MASK 0x7F /* Mask over minutes value */ 28 #define BQ32K_OF 0x80 /* Oscillator Failure flag */ 29 30 #define BQ32K_HOURS_MASK 0x3F /* Mask over hours value */ 31 #define BQ32K_CENT 0x40 /* Century flag */ 32 #define BQ32K_CENT_EN 0x80 /* Century flag enable bit */ 33 34 #define BQ32K_CALIBRATION 0x07 /* CAL_CFG1, calibration and control */ 35 #define BQ32K_TCH2 0x08 /* Trickle charge enable */ 36 #define BQ32K_CFG2 0x09 /* Trickle charger control */ 37 38 struct bq32k_regs { 39 uint8_t seconds; 40 uint8_t minutes; 41 uint8_t cent_hours; 42 uint8_t day; 43 uint8_t date; 44 uint8_t month; 45 uint8_t years; 46 }; 47 48 static struct i2c_driver bq32k_driver; 49 50 static int bq32k_read(struct device *dev, void *data, uint8_t off, uint8_t len) 51 { 52 struct i2c_client *client = to_i2c_client(dev); 53 struct i2c_msg msgs[] = { 54 { 55 .addr = client->addr, 56 .flags = 0, 57 .len = 1, 58 .buf = &off, 59 }, { 60 .addr = client->addr, 61 .flags = I2C_M_RD, 62 .len = len, 63 .buf = data, 64 } 65 }; 66 67 if (i2c_transfer(client->adapter, msgs, 2) == 2) 68 return 0; 69 70 return -EIO; 71 } 72 73 static int bq32k_write(struct device *dev, void *data, uint8_t off, uint8_t len) 74 { 75 struct i2c_client *client = to_i2c_client(dev); 76 uint8_t buffer[len + 1]; 77 78 buffer[0] = off; 79 memcpy(&buffer[1], data, len); 80 81 if (i2c_master_send(client, buffer, len + 1) == len + 1) 82 return 0; 83 84 return -EIO; 85 } 86 87 static int bq32k_rtc_read_time(struct device *dev, struct rtc_time *tm) 88 { 89 struct bq32k_regs regs; 90 int error; 91 92 error = bq32k_read(dev, ®s, 0, sizeof(regs)); 93 if (error) 94 return error; 95 96 /* 97 * In case of oscillator failure, the register contents should be 98 * considered invalid. The flag is cleared the next time the RTC is set. 99 */ 100 if (regs.minutes & BQ32K_OF) 101 return -EINVAL; 102 103 tm->tm_sec = bcd2bin(regs.seconds & BQ32K_SECONDS_MASK); 104 tm->tm_min = bcd2bin(regs.minutes & BQ32K_MINUTES_MASK); 105 tm->tm_hour = bcd2bin(regs.cent_hours & BQ32K_HOURS_MASK); 106 tm->tm_mday = bcd2bin(regs.date); 107 tm->tm_wday = bcd2bin(regs.day) - 1; 108 tm->tm_mon = bcd2bin(regs.month) - 1; 109 tm->tm_year = bcd2bin(regs.years) + 110 ((regs.cent_hours & BQ32K_CENT) ? 100 : 0); 111 112 return rtc_valid_tm(tm); 113 } 114 115 static int bq32k_rtc_set_time(struct device *dev, struct rtc_time *tm) 116 { 117 struct bq32k_regs regs; 118 119 regs.seconds = bin2bcd(tm->tm_sec); 120 regs.minutes = bin2bcd(tm->tm_min); 121 regs.cent_hours = bin2bcd(tm->tm_hour) | BQ32K_CENT_EN; 122 regs.day = bin2bcd(tm->tm_wday + 1); 123 regs.date = bin2bcd(tm->tm_mday); 124 regs.month = bin2bcd(tm->tm_mon + 1); 125 126 if (tm->tm_year >= 100) { 127 regs.cent_hours |= BQ32K_CENT; 128 regs.years = bin2bcd(tm->tm_year - 100); 129 } else 130 regs.years = bin2bcd(tm->tm_year); 131 132 return bq32k_write(dev, ®s, 0, sizeof(regs)); 133 } 134 135 static const struct rtc_class_ops bq32k_rtc_ops = { 136 .read_time = bq32k_rtc_read_time, 137 .set_time = bq32k_rtc_set_time, 138 }; 139 140 static int trickle_charger_of_init(struct device *dev, struct device_node *node) 141 { 142 unsigned char reg; 143 int error; 144 u32 ohms = 0; 145 146 if (of_property_read_u32(node, "trickle-resistor-ohms" , &ohms)) 147 return 0; 148 149 switch (ohms) { 150 case 180+940: 151 /* 152 * TCHE[3:0] == 0x05, TCH2 == 1, TCFE == 0 (charging 153 * over diode and 940ohm resistor) 154 */ 155 156 if (of_property_read_bool(node, "trickle-diode-disable")) { 157 dev_err(dev, "diode and resistor mismatch\n"); 158 return -EINVAL; 159 } 160 reg = 0x05; 161 break; 162 163 case 180+20000: 164 /* diode disabled */ 165 166 if (!of_property_read_bool(node, "trickle-diode-disable")) { 167 dev_err(dev, "bq32k: diode and resistor mismatch\n"); 168 return -EINVAL; 169 } 170 reg = 0x45; 171 break; 172 173 default: 174 dev_err(dev, "invalid resistor value (%d)\n", ohms); 175 return -EINVAL; 176 } 177 178 error = bq32k_write(dev, ®, BQ32K_CFG2, 1); 179 if (error) 180 return error; 181 182 reg = 0x20; 183 error = bq32k_write(dev, ®, BQ32K_TCH2, 1); 184 if (error) 185 return error; 186 187 dev_info(dev, "Enabled trickle RTC battery charge.\n"); 188 return 0; 189 } 190 191 static int bq32k_probe(struct i2c_client *client, 192 const struct i2c_device_id *id) 193 { 194 struct device *dev = &client->dev; 195 struct rtc_device *rtc; 196 uint8_t reg; 197 int error; 198 199 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) 200 return -ENODEV; 201 202 /* Check Oscillator Stop flag */ 203 error = bq32k_read(dev, ®, BQ32K_SECONDS, 1); 204 if (!error && (reg & BQ32K_STOP)) { 205 dev_warn(dev, "Oscillator was halted. Restarting...\n"); 206 reg &= ~BQ32K_STOP; 207 error = bq32k_write(dev, ®, BQ32K_SECONDS, 1); 208 } 209 if (error) 210 return error; 211 212 /* Check Oscillator Failure flag */ 213 error = bq32k_read(dev, ®, BQ32K_MINUTES, 1); 214 if (error) 215 return error; 216 if (reg & BQ32K_OF) 217 dev_warn(dev, "Oscillator Failure. Check RTC battery.\n"); 218 219 if (client->dev.of_node) 220 trickle_charger_of_init(dev, client->dev.of_node); 221 222 rtc = devm_rtc_device_register(&client->dev, bq32k_driver.driver.name, 223 &bq32k_rtc_ops, THIS_MODULE); 224 if (IS_ERR(rtc)) 225 return PTR_ERR(rtc); 226 227 i2c_set_clientdata(client, rtc); 228 229 return 0; 230 } 231 232 static const struct i2c_device_id bq32k_id[] = { 233 { "bq32000", 0 }, 234 { } 235 }; 236 MODULE_DEVICE_TABLE(i2c, bq32k_id); 237 238 static struct i2c_driver bq32k_driver = { 239 .driver = { 240 .name = "bq32k", 241 }, 242 .probe = bq32k_probe, 243 .id_table = bq32k_id, 244 }; 245 246 module_i2c_driver(bq32k_driver); 247 248 MODULE_AUTHOR("Semihalf, Piotr Ziecik <kosmo@semihalf.com>"); 249 MODULE_DESCRIPTION("TI BQ32000 I2C RTC driver"); 250 MODULE_LICENSE("GPL"); 251