1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Driver for TI BQ32000 RTC. 4 * 5 * Copyright (C) 2009 Semihalf. 6 * Copyright (C) 2014 Pavel Machek <pavel@denx.de> 7 * 8 * You can get hardware description at 9 * https://www.ti.com/lit/ds/symlink/bq32000.pdf 10 */ 11 12 #include <linux/module.h> 13 #include <linux/i2c.h> 14 #include <linux/rtc.h> 15 #include <linux/init.h> 16 #include <linux/errno.h> 17 #include <linux/bcd.h> 18 19 #define BQ32K_SECONDS 0x00 /* Seconds register address */ 20 #define BQ32K_SECONDS_MASK 0x7F /* Mask over seconds value */ 21 #define BQ32K_STOP 0x80 /* Oscillator Stop flat */ 22 23 #define BQ32K_MINUTES 0x01 /* Minutes register address */ 24 #define BQ32K_MINUTES_MASK 0x7F /* Mask over minutes value */ 25 #define BQ32K_OF 0x80 /* Oscillator Failure flag */ 26 27 #define BQ32K_HOURS_MASK 0x3F /* Mask over hours value */ 28 #define BQ32K_CENT 0x40 /* Century flag */ 29 #define BQ32K_CENT_EN 0x80 /* Century flag enable bit */ 30 31 #define BQ32K_CALIBRATION 0x07 /* CAL_CFG1, calibration and control */ 32 #define BQ32K_TCH2 0x08 /* Trickle charge enable */ 33 #define BQ32K_CFG2 0x09 /* Trickle charger control */ 34 #define BQ32K_TCFE BIT(6) /* Trickle charge FET bypass */ 35 36 #define MAX_LEN 10 /* Maximum number of consecutive 37 * register for this particular RTC. 38 */ 39 40 struct bq32k_regs { 41 uint8_t seconds; 42 uint8_t minutes; 43 uint8_t cent_hours; 44 uint8_t day; 45 uint8_t date; 46 uint8_t month; 47 uint8_t years; 48 }; 49 50 static struct i2c_driver bq32k_driver; 51 52 static int bq32k_read(struct device *dev, void *data, uint8_t off, uint8_t len) 53 { 54 struct i2c_client *client = to_i2c_client(dev); 55 struct i2c_msg msgs[] = { 56 { 57 .addr = client->addr, 58 .flags = 0, 59 .len = 1, 60 .buf = &off, 61 }, { 62 .addr = client->addr, 63 .flags = I2C_M_RD, 64 .len = len, 65 .buf = data, 66 } 67 }; 68 69 if (i2c_transfer(client->adapter, msgs, 2) == 2) 70 return 0; 71 72 return -EIO; 73 } 74 75 static int bq32k_write(struct device *dev, void *data, uint8_t off, uint8_t len) 76 { 77 struct i2c_client *client = to_i2c_client(dev); 78 uint8_t buffer[MAX_LEN + 1]; 79 80 buffer[0] = off; 81 memcpy(&buffer[1], data, len); 82 83 if (i2c_master_send(client, buffer, len + 1) == len + 1) 84 return 0; 85 86 return -EIO; 87 } 88 89 static int bq32k_rtc_read_time(struct device *dev, struct rtc_time *tm) 90 { 91 struct bq32k_regs regs; 92 int error; 93 94 error = bq32k_read(dev, ®s, 0, sizeof(regs)); 95 if (error) 96 return error; 97 98 /* 99 * In case of oscillator failure, the register contents should be 100 * considered invalid. The flag is cleared the next time the RTC is set. 101 */ 102 if (regs.minutes & BQ32K_OF) 103 return -EINVAL; 104 105 tm->tm_sec = bcd2bin(regs.seconds & BQ32K_SECONDS_MASK); 106 tm->tm_min = bcd2bin(regs.minutes & BQ32K_MINUTES_MASK); 107 tm->tm_hour = bcd2bin(regs.cent_hours & BQ32K_HOURS_MASK); 108 tm->tm_mday = bcd2bin(regs.date); 109 tm->tm_wday = bcd2bin(regs.day) - 1; 110 tm->tm_mon = bcd2bin(regs.month) - 1; 111 tm->tm_year = bcd2bin(regs.years) + 112 ((regs.cent_hours & BQ32K_CENT) ? 100 : 0); 113 114 return 0; 115 } 116 117 static int bq32k_rtc_set_time(struct device *dev, struct rtc_time *tm) 118 { 119 struct bq32k_regs regs; 120 121 regs.seconds = bin2bcd(tm->tm_sec); 122 regs.minutes = bin2bcd(tm->tm_min); 123 regs.cent_hours = bin2bcd(tm->tm_hour) | BQ32K_CENT_EN; 124 regs.day = bin2bcd(tm->tm_wday + 1); 125 regs.date = bin2bcd(tm->tm_mday); 126 regs.month = bin2bcd(tm->tm_mon + 1); 127 128 if (tm->tm_year >= 100) { 129 regs.cent_hours |= BQ32K_CENT; 130 regs.years = bin2bcd(tm->tm_year - 100); 131 } else 132 regs.years = bin2bcd(tm->tm_year); 133 134 return bq32k_write(dev, ®s, 0, sizeof(regs)); 135 } 136 137 static const struct rtc_class_ops bq32k_rtc_ops = { 138 .read_time = bq32k_rtc_read_time, 139 .set_time = bq32k_rtc_set_time, 140 }; 141 142 static int trickle_charger_of_init(struct device *dev, struct device_node *node) 143 { 144 unsigned char reg; 145 int error; 146 u32 ohms = 0; 147 148 if (of_property_read_u32(node, "trickle-resistor-ohms" , &ohms)) 149 return 0; 150 151 switch (ohms) { 152 case 180+940: 153 /* 154 * TCHE[3:0] == 0x05, TCH2 == 1, TCFE == 0 (charging 155 * over diode and 940ohm resistor) 156 */ 157 158 if (of_property_read_bool(node, "trickle-diode-disable")) { 159 dev_err(dev, "diode and resistor mismatch\n"); 160 return -EINVAL; 161 } 162 reg = 0x05; 163 break; 164 165 case 180+20000: 166 /* diode disabled */ 167 168 if (!of_property_read_bool(node, "trickle-diode-disable")) { 169 dev_err(dev, "bq32k: diode and resistor mismatch\n"); 170 return -EINVAL; 171 } 172 reg = 0x45; 173 break; 174 175 default: 176 dev_err(dev, "invalid resistor value (%d)\n", ohms); 177 return -EINVAL; 178 } 179 180 error = bq32k_write(dev, ®, BQ32K_CFG2, 1); 181 if (error) 182 return error; 183 184 reg = 0x20; 185 error = bq32k_write(dev, ®, BQ32K_TCH2, 1); 186 if (error) 187 return error; 188 189 dev_info(dev, "Enabled trickle RTC battery charge.\n"); 190 return 0; 191 } 192 193 static ssize_t bq32k_sysfs_show_tricklecharge_bypass(struct device *dev, 194 struct device_attribute *attr, 195 char *buf) 196 { 197 int reg, error; 198 199 error = bq32k_read(dev, ®, BQ32K_CFG2, 1); 200 if (error) 201 return error; 202 203 return sprintf(buf, "%d\n", (reg & BQ32K_TCFE) ? 1 : 0); 204 } 205 206 static ssize_t bq32k_sysfs_store_tricklecharge_bypass(struct device *dev, 207 struct device_attribute *attr, 208 const char *buf, size_t count) 209 { 210 int reg, enable, error; 211 212 if (kstrtoint(buf, 0, &enable)) 213 return -EINVAL; 214 215 error = bq32k_read(dev, ®, BQ32K_CFG2, 1); 216 if (error) 217 return error; 218 219 if (enable) { 220 reg |= BQ32K_TCFE; 221 error = bq32k_write(dev, ®, BQ32K_CFG2, 1); 222 if (error) 223 return error; 224 225 dev_info(dev, "Enabled trickle charge FET bypass.\n"); 226 } else { 227 reg &= ~BQ32K_TCFE; 228 error = bq32k_write(dev, ®, BQ32K_CFG2, 1); 229 if (error) 230 return error; 231 232 dev_info(dev, "Disabled trickle charge FET bypass.\n"); 233 } 234 235 return count; 236 } 237 238 static DEVICE_ATTR(trickle_charge_bypass, 0644, 239 bq32k_sysfs_show_tricklecharge_bypass, 240 bq32k_sysfs_store_tricklecharge_bypass); 241 242 static int bq32k_sysfs_register(struct device *dev) 243 { 244 return device_create_file(dev, &dev_attr_trickle_charge_bypass); 245 } 246 247 static void bq32k_sysfs_unregister(struct device *dev) 248 { 249 device_remove_file(dev, &dev_attr_trickle_charge_bypass); 250 } 251 252 static int bq32k_probe(struct i2c_client *client) 253 { 254 struct device *dev = &client->dev; 255 struct rtc_device *rtc; 256 uint8_t reg; 257 int error; 258 259 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) 260 return -ENODEV; 261 262 /* Check Oscillator Stop flag */ 263 error = bq32k_read(dev, ®, BQ32K_SECONDS, 1); 264 if (!error && (reg & BQ32K_STOP)) { 265 dev_warn(dev, "Oscillator was halted. Restarting...\n"); 266 reg &= ~BQ32K_STOP; 267 error = bq32k_write(dev, ®, BQ32K_SECONDS, 1); 268 } 269 if (error) 270 return error; 271 272 /* Check Oscillator Failure flag */ 273 error = bq32k_read(dev, ®, BQ32K_MINUTES, 1); 274 if (error) 275 return error; 276 if (reg & BQ32K_OF) 277 dev_warn(dev, "Oscillator Failure. Check RTC battery.\n"); 278 279 if (client->dev.of_node) 280 trickle_charger_of_init(dev, client->dev.of_node); 281 282 rtc = devm_rtc_device_register(&client->dev, bq32k_driver.driver.name, 283 &bq32k_rtc_ops, THIS_MODULE); 284 if (IS_ERR(rtc)) 285 return PTR_ERR(rtc); 286 287 error = bq32k_sysfs_register(&client->dev); 288 if (error) { 289 dev_err(&client->dev, 290 "Unable to create sysfs entries for rtc bq32000\n"); 291 return error; 292 } 293 294 295 i2c_set_clientdata(client, rtc); 296 297 return 0; 298 } 299 300 static int bq32k_remove(struct i2c_client *client) 301 { 302 bq32k_sysfs_unregister(&client->dev); 303 304 return 0; 305 } 306 307 static const struct i2c_device_id bq32k_id[] = { 308 { "bq32000", 0 }, 309 { } 310 }; 311 MODULE_DEVICE_TABLE(i2c, bq32k_id); 312 313 static const __maybe_unused struct of_device_id bq32k_of_match[] = { 314 { .compatible = "ti,bq32000" }, 315 { } 316 }; 317 MODULE_DEVICE_TABLE(of, bq32k_of_match); 318 319 static struct i2c_driver bq32k_driver = { 320 .driver = { 321 .name = "bq32k", 322 .of_match_table = of_match_ptr(bq32k_of_match), 323 }, 324 .probe_new = bq32k_probe, 325 .remove = bq32k_remove, 326 .id_table = bq32k_id, 327 }; 328 329 module_i2c_driver(bq32k_driver); 330 331 MODULE_AUTHOR("Semihalf, Piotr Ziecik <kosmo@semihalf.com>"); 332 MODULE_DESCRIPTION("TI BQ32000 I2C RTC driver"); 333 MODULE_LICENSE("GPL"); 334