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 #define BQ32K_TCFE BIT(6) /* Trickle charge FET bypass */ 38 39 #define MAX_LEN 10 /* Maximum number of consecutive 40 * register for this particular RTC. 41 */ 42 43 struct bq32k_regs { 44 uint8_t seconds; 45 uint8_t minutes; 46 uint8_t cent_hours; 47 uint8_t day; 48 uint8_t date; 49 uint8_t month; 50 uint8_t years; 51 }; 52 53 static struct i2c_driver bq32k_driver; 54 55 static int bq32k_read(struct device *dev, void *data, uint8_t off, uint8_t len) 56 { 57 struct i2c_client *client = to_i2c_client(dev); 58 struct i2c_msg msgs[] = { 59 { 60 .addr = client->addr, 61 .flags = 0, 62 .len = 1, 63 .buf = &off, 64 }, { 65 .addr = client->addr, 66 .flags = I2C_M_RD, 67 .len = len, 68 .buf = data, 69 } 70 }; 71 72 if (i2c_transfer(client->adapter, msgs, 2) == 2) 73 return 0; 74 75 return -EIO; 76 } 77 78 static int bq32k_write(struct device *dev, void *data, uint8_t off, uint8_t len) 79 { 80 struct i2c_client *client = to_i2c_client(dev); 81 uint8_t buffer[MAX_LEN + 1]; 82 83 buffer[0] = off; 84 memcpy(&buffer[1], data, len); 85 86 if (i2c_master_send(client, buffer, len + 1) == len + 1) 87 return 0; 88 89 return -EIO; 90 } 91 92 static int bq32k_rtc_read_time(struct device *dev, struct rtc_time *tm) 93 { 94 struct bq32k_regs regs; 95 int error; 96 97 error = bq32k_read(dev, ®s, 0, sizeof(regs)); 98 if (error) 99 return error; 100 101 /* 102 * In case of oscillator failure, the register contents should be 103 * considered invalid. The flag is cleared the next time the RTC is set. 104 */ 105 if (regs.minutes & BQ32K_OF) 106 return -EINVAL; 107 108 tm->tm_sec = bcd2bin(regs.seconds & BQ32K_SECONDS_MASK); 109 tm->tm_min = bcd2bin(regs.minutes & BQ32K_MINUTES_MASK); 110 tm->tm_hour = bcd2bin(regs.cent_hours & BQ32K_HOURS_MASK); 111 tm->tm_mday = bcd2bin(regs.date); 112 tm->tm_wday = bcd2bin(regs.day) - 1; 113 tm->tm_mon = bcd2bin(regs.month) - 1; 114 tm->tm_year = bcd2bin(regs.years) + 115 ((regs.cent_hours & BQ32K_CENT) ? 100 : 0); 116 117 return 0; 118 } 119 120 static int bq32k_rtc_set_time(struct device *dev, struct rtc_time *tm) 121 { 122 struct bq32k_regs regs; 123 124 regs.seconds = bin2bcd(tm->tm_sec); 125 regs.minutes = bin2bcd(tm->tm_min); 126 regs.cent_hours = bin2bcd(tm->tm_hour) | BQ32K_CENT_EN; 127 regs.day = bin2bcd(tm->tm_wday + 1); 128 regs.date = bin2bcd(tm->tm_mday); 129 regs.month = bin2bcd(tm->tm_mon + 1); 130 131 if (tm->tm_year >= 100) { 132 regs.cent_hours |= BQ32K_CENT; 133 regs.years = bin2bcd(tm->tm_year - 100); 134 } else 135 regs.years = bin2bcd(tm->tm_year); 136 137 return bq32k_write(dev, ®s, 0, sizeof(regs)); 138 } 139 140 static const struct rtc_class_ops bq32k_rtc_ops = { 141 .read_time = bq32k_rtc_read_time, 142 .set_time = bq32k_rtc_set_time, 143 }; 144 145 static int trickle_charger_of_init(struct device *dev, struct device_node *node) 146 { 147 unsigned char reg; 148 int error; 149 u32 ohms = 0; 150 151 if (of_property_read_u32(node, "trickle-resistor-ohms" , &ohms)) 152 return 0; 153 154 switch (ohms) { 155 case 180+940: 156 /* 157 * TCHE[3:0] == 0x05, TCH2 == 1, TCFE == 0 (charging 158 * over diode and 940ohm resistor) 159 */ 160 161 if (of_property_read_bool(node, "trickle-diode-disable")) { 162 dev_err(dev, "diode and resistor mismatch\n"); 163 return -EINVAL; 164 } 165 reg = 0x05; 166 break; 167 168 case 180+20000: 169 /* diode disabled */ 170 171 if (!of_property_read_bool(node, "trickle-diode-disable")) { 172 dev_err(dev, "bq32k: diode and resistor mismatch\n"); 173 return -EINVAL; 174 } 175 reg = 0x45; 176 break; 177 178 default: 179 dev_err(dev, "invalid resistor value (%d)\n", ohms); 180 return -EINVAL; 181 } 182 183 error = bq32k_write(dev, ®, BQ32K_CFG2, 1); 184 if (error) 185 return error; 186 187 reg = 0x20; 188 error = bq32k_write(dev, ®, BQ32K_TCH2, 1); 189 if (error) 190 return error; 191 192 dev_info(dev, "Enabled trickle RTC battery charge.\n"); 193 return 0; 194 } 195 196 static ssize_t bq32k_sysfs_show_tricklecharge_bypass(struct device *dev, 197 struct device_attribute *attr, 198 char *buf) 199 { 200 int reg, error; 201 202 error = bq32k_read(dev, ®, BQ32K_CFG2, 1); 203 if (error) 204 return error; 205 206 return sprintf(buf, "%d\n", (reg & BQ32K_TCFE) ? 1 : 0); 207 } 208 209 static ssize_t bq32k_sysfs_store_tricklecharge_bypass(struct device *dev, 210 struct device_attribute *attr, 211 const char *buf, size_t count) 212 { 213 int reg, enable, error; 214 215 if (kstrtoint(buf, 0, &enable)) 216 return -EINVAL; 217 218 error = bq32k_read(dev, ®, BQ32K_CFG2, 1); 219 if (error) 220 return error; 221 222 if (enable) { 223 reg |= BQ32K_TCFE; 224 error = bq32k_write(dev, ®, BQ32K_CFG2, 1); 225 if (error) 226 return error; 227 228 dev_info(dev, "Enabled trickle charge FET bypass.\n"); 229 } else { 230 reg &= ~BQ32K_TCFE; 231 error = bq32k_write(dev, ®, BQ32K_CFG2, 1); 232 if (error) 233 return error; 234 235 dev_info(dev, "Disabled trickle charge FET bypass.\n"); 236 } 237 238 return count; 239 } 240 241 static DEVICE_ATTR(trickle_charge_bypass, 0644, 242 bq32k_sysfs_show_tricklecharge_bypass, 243 bq32k_sysfs_store_tricklecharge_bypass); 244 245 static int bq32k_sysfs_register(struct device *dev) 246 { 247 return device_create_file(dev, &dev_attr_trickle_charge_bypass); 248 } 249 250 static void bq32k_sysfs_unregister(struct device *dev) 251 { 252 device_remove_file(dev, &dev_attr_trickle_charge_bypass); 253 } 254 255 static int bq32k_probe(struct i2c_client *client, 256 const struct i2c_device_id *id) 257 { 258 struct device *dev = &client->dev; 259 struct rtc_device *rtc; 260 uint8_t reg; 261 int error; 262 263 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) 264 return -ENODEV; 265 266 /* Check Oscillator Stop flag */ 267 error = bq32k_read(dev, ®, BQ32K_SECONDS, 1); 268 if (!error && (reg & BQ32K_STOP)) { 269 dev_warn(dev, "Oscillator was halted. Restarting...\n"); 270 reg &= ~BQ32K_STOP; 271 error = bq32k_write(dev, ®, BQ32K_SECONDS, 1); 272 } 273 if (error) 274 return error; 275 276 /* Check Oscillator Failure flag */ 277 error = bq32k_read(dev, ®, BQ32K_MINUTES, 1); 278 if (error) 279 return error; 280 if (reg & BQ32K_OF) 281 dev_warn(dev, "Oscillator Failure. Check RTC battery.\n"); 282 283 if (client->dev.of_node) 284 trickle_charger_of_init(dev, client->dev.of_node); 285 286 rtc = devm_rtc_device_register(&client->dev, bq32k_driver.driver.name, 287 &bq32k_rtc_ops, THIS_MODULE); 288 if (IS_ERR(rtc)) 289 return PTR_ERR(rtc); 290 291 error = bq32k_sysfs_register(&client->dev); 292 if (error) { 293 dev_err(&client->dev, 294 "Unable to create sysfs entries for rtc bq32000\n"); 295 return error; 296 } 297 298 299 i2c_set_clientdata(client, rtc); 300 301 return 0; 302 } 303 304 static int bq32k_remove(struct i2c_client *client) 305 { 306 bq32k_sysfs_unregister(&client->dev); 307 308 return 0; 309 } 310 311 static const struct i2c_device_id bq32k_id[] = { 312 { "bq32000", 0 }, 313 { } 314 }; 315 MODULE_DEVICE_TABLE(i2c, bq32k_id); 316 317 static const struct of_device_id bq32k_of_match[] = { 318 { .compatible = "ti,bq32000" }, 319 { } 320 }; 321 MODULE_DEVICE_TABLE(of, bq32k_of_match); 322 323 static struct i2c_driver bq32k_driver = { 324 .driver = { 325 .name = "bq32k", 326 .of_match_table = of_match_ptr(bq32k_of_match), 327 }, 328 .probe = bq32k_probe, 329 .remove = bq32k_remove, 330 .id_table = bq32k_id, 331 }; 332 333 module_i2c_driver(bq32k_driver); 334 335 MODULE_AUTHOR("Semihalf, Piotr Ziecik <kosmo@semihalf.com>"); 336 MODULE_DESCRIPTION("TI BQ32000 I2C RTC driver"); 337 MODULE_LICENSE("GPL"); 338