| 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", 0 }, |
| 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_new = 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"); |