diff options
Diffstat (limited to 'drivers/rtc/rtc-bq32k.c')
| -rw-r--r-- | drivers/rtc/rtc-bq32k.c | 334 |
1 files changed, 334 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-bq32k.c b/drivers/rtc/rtc-bq32k.c new file mode 100644 index 000000000..933e42372 --- /dev/null +++ b/drivers/rtc/rtc-bq32k.c @@ -0,0 +1,334 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Driver for TI BQ32000 RTC. + * + * Copyright (C) 2009 Semihalf. + * Copyright (C) 2014 Pavel Machek <pavel@denx.de> + * + * You can get hardware description at + * https://www.ti.com/lit/ds/symlink/bq32000.pdf + */ + +#include <linux/module.h> +#include <linux/i2c.h> +#include <linux/rtc.h> +#include <linux/init.h> +#include <linux/errno.h> +#include <linux/bcd.h> + +#define BQ32K_SECONDS 0x00 /* Seconds register address */ +#define BQ32K_SECONDS_MASK 0x7F /* Mask over seconds value */ +#define BQ32K_STOP 0x80 /* Oscillator Stop flat */ + +#define BQ32K_MINUTES 0x01 /* Minutes register address */ +#define BQ32K_MINUTES_MASK 0x7F /* Mask over minutes value */ +#define BQ32K_OF 0x80 /* Oscillator Failure flag */ + +#define BQ32K_HOURS_MASK 0x3F /* Mask over hours value */ +#define BQ32K_CENT 0x40 /* Century flag */ +#define BQ32K_CENT_EN 0x80 /* Century flag enable bit */ + +#define BQ32K_CALIBRATION 0x07 /* CAL_CFG1, calibration and control */ +#define BQ32K_TCH2 0x08 /* Trickle charge enable */ +#define BQ32K_CFG2 0x09 /* Trickle charger control */ +#define BQ32K_TCFE BIT(6) /* Trickle charge FET bypass */ + +#define MAX_LEN 10 /* Maximum number of consecutive + * register for this particular RTC. + */ + +struct bq32k_regs { + uint8_t seconds; + uint8_t minutes; + uint8_t cent_hours; + uint8_t day; + uint8_t date; + uint8_t month; + uint8_t years; +}; + +static struct i2c_driver bq32k_driver; + +static int bq32k_read(struct device *dev, void *data, uint8_t off, uint8_t len) +{ + struct i2c_client *client = to_i2c_client(dev); + struct i2c_msg msgs[] = { + { + .addr = client->addr, + .flags = 0, + .len = 1, + .buf = &off, + }, { + .addr = client->addr, + .flags = I2C_M_RD, + .len = len, + .buf = data, + } + }; + + if (i2c_transfer(client->adapter, msgs, 2) == 2) + return 0; + + return -EIO; +} + +static int bq32k_write(struct device *dev, void *data, uint8_t off, uint8_t len) +{ + struct i2c_client *client = to_i2c_client(dev); + uint8_t buffer[MAX_LEN + 1]; + + buffer[0] = off; + memcpy(&buffer[1], data, len); + + if (i2c_master_send(client, buffer, len + 1) == len + 1) + return 0; + + return -EIO; +} + +static int bq32k_rtc_read_time(struct device *dev, struct rtc_time *tm) +{ + struct bq32k_regs regs; + int error; + + error = bq32k_read(dev, ®s, 0, sizeof(regs)); + if (error) + return error; + + /* + * In case of oscillator failure, the register contents should be + * considered invalid. The flag is cleared the next time the RTC is set. + */ + if (regs.minutes & BQ32K_OF) + return -EINVAL; + + tm->tm_sec = bcd2bin(regs.seconds & BQ32K_SECONDS_MASK); + tm->tm_min = bcd2bin(regs.minutes & BQ32K_MINUTES_MASK); + tm->tm_hour = bcd2bin(regs.cent_hours & BQ32K_HOURS_MASK); + tm->tm_mday = bcd2bin(regs.date); + tm->tm_wday = bcd2bin(regs.day) - 1; + tm->tm_mon = bcd2bin(regs.month) - 1; + tm->tm_year = bcd2bin(regs.years) + + ((regs.cent_hours & BQ32K_CENT) ? 100 : 0); + + return 0; +} + +static int bq32k_rtc_set_time(struct device *dev, struct rtc_time *tm) +{ + struct bq32k_regs regs; + + regs.seconds = bin2bcd(tm->tm_sec); + regs.minutes = bin2bcd(tm->tm_min); + regs.cent_hours = bin2bcd(tm->tm_hour) | BQ32K_CENT_EN; + regs.day = bin2bcd(tm->tm_wday + 1); + regs.date = bin2bcd(tm->tm_mday); + regs.month = bin2bcd(tm->tm_mon + 1); + + if (tm->tm_year >= 100) { + regs.cent_hours |= BQ32K_CENT; + regs.years = bin2bcd(tm->tm_year - 100); + } else + regs.years = bin2bcd(tm->tm_year); + + return bq32k_write(dev, ®s, 0, sizeof(regs)); +} + +static const struct rtc_class_ops bq32k_rtc_ops = { + .read_time = bq32k_rtc_read_time, + .set_time = bq32k_rtc_set_time, +}; + +static int trickle_charger_of_init(struct device *dev, struct device_node *node) +{ + unsigned char reg; + int error; + u32 ohms = 0; + + if (of_property_read_u32(node, "trickle-resistor-ohms" , &ohms)) + return 0; + + switch (ohms) { + case 180+940: + /* + * TCHE[3:0] == 0x05, TCH2 == 1, TCFE == 0 (charging + * over diode and 940ohm resistor) + */ + + if (of_property_read_bool(node, "trickle-diode-disable")) { + dev_err(dev, "diode and resistor mismatch\n"); + return -EINVAL; + } + reg = 0x05; + break; + + case 180+20000: + /* diode disabled */ + + if (!of_property_read_bool(node, "trickle-diode-disable")) { + dev_err(dev, "bq32k: diode and resistor mismatch\n"); + return -EINVAL; + } + reg = 0x45; + break; + + default: + dev_err(dev, "invalid resistor value (%d)\n", ohms); + return -EINVAL; + } + + error = bq32k_write(dev, ®, BQ32K_CFG2, 1); + if (error) + return error; + + reg = 0x20; + error = bq32k_write(dev, ®, BQ32K_TCH2, 1); + if (error) + return error; + + dev_info(dev, "Enabled trickle RTC battery charge.\n"); + return 0; +} + +static ssize_t bq32k_sysfs_show_tricklecharge_bypass(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + int reg, error; + + error = bq32k_read(dev, ®, BQ32K_CFG2, 1); + if (error) + return error; + + return sprintf(buf, "%d\n", (reg & BQ32K_TCFE) ? 1 : 0); +} + +static ssize_t bq32k_sysfs_store_tricklecharge_bypass(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + int reg, enable, error; + + if (kstrtoint(buf, 0, &enable)) + return -EINVAL; + + error = bq32k_read(dev, ®, BQ32K_CFG2, 1); + if (error) + return error; + + if (enable) { + reg |= BQ32K_TCFE; + error = bq32k_write(dev, ®, BQ32K_CFG2, 1); + if (error) + return error; + + dev_info(dev, "Enabled trickle charge FET bypass.\n"); + } else { + reg &= ~BQ32K_TCFE; + error = bq32k_write(dev, ®, BQ32K_CFG2, 1); + if (error) + return error; + + dev_info(dev, "Disabled trickle charge FET bypass.\n"); + } + + return count; +} + +static DEVICE_ATTR(trickle_charge_bypass, 0644, + bq32k_sysfs_show_tricklecharge_bypass, + bq32k_sysfs_store_tricklecharge_bypass); + +static int bq32k_sysfs_register(struct device *dev) +{ + return device_create_file(dev, &dev_attr_trickle_charge_bypass); +} + +static void bq32k_sysfs_unregister(struct device *dev) +{ + device_remove_file(dev, &dev_attr_trickle_charge_bypass); +} + +static int bq32k_probe(struct i2c_client *client, + const struct i2c_device_id *id) +{ + struct device *dev = &client->dev; + struct rtc_device *rtc; + uint8_t reg; + int error; + + if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) + return -ENODEV; + + /* Check Oscillator Stop flag */ + error = bq32k_read(dev, ®, BQ32K_SECONDS, 1); + if (!error && (reg & BQ32K_STOP)) { + dev_warn(dev, "Oscillator was halted. Restarting...\n"); + reg &= ~BQ32K_STOP; + error = bq32k_write(dev, ®, BQ32K_SECONDS, 1); + } + if (error) + return error; + + /* Check Oscillator Failure flag */ + error = bq32k_read(dev, ®, BQ32K_MINUTES, 1); + if (error) + return error; + if (reg & BQ32K_OF) + dev_warn(dev, "Oscillator Failure. Check RTC battery.\n"); + + if (client->dev.of_node) + trickle_charger_of_init(dev, client->dev.of_node); + + rtc = devm_rtc_device_register(&client->dev, bq32k_driver.driver.name, + &bq32k_rtc_ops, THIS_MODULE); + if (IS_ERR(rtc)) + return PTR_ERR(rtc); + + error = bq32k_sysfs_register(&client->dev); + if (error) { + dev_err(&client->dev, + "Unable to create sysfs entries for rtc bq32000\n"); + return error; + } + + + i2c_set_clientdata(client, rtc); + + return 0; +} + +static int bq32k_remove(struct i2c_client *client) +{ + bq32k_sysfs_unregister(&client->dev); + + return 0; +} + +static const struct i2c_device_id bq32k_id[] = { + { "bq32000", 0 }, + { } +}; +MODULE_DEVICE_TABLE(i2c, bq32k_id); + +static const struct of_device_id bq32k_of_match[] = { + { .compatible = "ti,bq32000" }, + { } +}; +MODULE_DEVICE_TABLE(of, bq32k_of_match); + +static struct i2c_driver bq32k_driver = { + .driver = { + .name = "bq32k", + .of_match_table = of_match_ptr(bq32k_of_match), + }, + .probe = bq32k_probe, + .remove = bq32k_remove, + .id_table = bq32k_id, +}; + +module_i2c_driver(bq32k_driver); + +MODULE_AUTHOR("Semihalf, Piotr Ziecik <kosmo@semihalf.com>"); +MODULE_DESCRIPTION("TI BQ32000 I2C RTC driver"); +MODULE_LICENSE("GPL"); |