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1// SPDX-License-Identifier: GPL-2.0-only2/*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 at9 * https://www.ti.com/lit/ds/symlink/bq32000.pdf10 */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 consecutive38 * register for this particular RTC.39 */40 41struct 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 51static struct i2c_driver bq32k_driver;52 53static 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 76static 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 90static 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 be101 * 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 118static 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 } else133 regs.years = bin2bcd(tm->tm_year);134 135 return bq32k_write(dev, ®s, 0, sizeof(regs));136}137 138static const struct rtc_class_ops bq32k_rtc_ops = {139 .read_time = bq32k_rtc_read_time,140 .set_time = bq32k_rtc_set_time,141};142 143static 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 (charging156 * 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 194static 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 207static 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 239static DEVICE_ATTR(trickle_charge_bypass, 0644,240 bq32k_sysfs_show_tricklecharge_bypass,241 bq32k_sysfs_store_tricklecharge_bypass);242 243static int bq32k_sysfs_register(struct device *dev)244{245 return device_create_file(dev, &dev_attr_trickle_charge_bypass);246}247 248static void bq32k_sysfs_unregister(struct device *dev)249{250 device_remove_file(dev, &dev_attr_trickle_charge_bypass);251}252 253static 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 301static void bq32k_remove(struct i2c_client *client)302{303 bq32k_sysfs_unregister(&client->dev);304}305 306static const struct i2c_device_id bq32k_id[] = {307 { "bq32000" },308 { }309};310MODULE_DEVICE_TABLE(i2c, bq32k_id);311 312static const __maybe_unused struct of_device_id bq32k_of_match[] = {313 { .compatible = "ti,bq32000" },314 { }315};316MODULE_DEVICE_TABLE(of, bq32k_of_match);317 318static 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 328module_i2c_driver(bq32k_driver);329 330MODULE_AUTHOR("Semihalf, Piotr Ziecik <kosmo@semihalf.com>");331MODULE_DESCRIPTION("TI BQ32000 I2C RTC driver");332MODULE_LICENSE("GPL");333