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