diff options
Diffstat (limited to 'drivers/rtc/rtc-bq32k.c')
| -rw-r--r-- | drivers/rtc/rtc-bq32k.c | 247 |
1 files changed, 247 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-bq32k.c b/drivers/rtc/rtc-bq32k.c new file mode 100644 index 000000000..92679df6d --- /dev/null +++ b/drivers/rtc/rtc-bq32k.c @@ -0,0 +1,247 @@ +/* + * Driver for TI BQ32000 RTC. + * + * Copyright (C) 2009 Semihalf. + * Copyright (C) 2014 Pavel Machek <pavel@denx.de> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * You can get hardware description at + * http://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 */ + +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[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; + + tm->tm_sec = bcd2bin(regs.seconds & BQ32K_SECONDS_MASK); + tm->tm_min = bcd2bin(regs.minutes & BQ32K_SECONDS_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 rtc_valid_tm(tm); +} + +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 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 && (reg & BQ32K_OF)) { + dev_warn(dev, "Oscillator Failure. Check RTC battery.\n"); + reg &= ~BQ32K_OF; + error = bq32k_write(dev, ®, BQ32K_MINUTES, 1); + } + if (error) + return error; + + if (client && 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); + + i2c_set_clientdata(client, rtc); + + return 0; +} + +static const struct i2c_device_id bq32k_id[] = { + { "bq32000", 0 }, + { } +}; +MODULE_DEVICE_TABLE(i2c, bq32k_id); + +static struct i2c_driver bq32k_driver = { + .driver = { + .name = "bq32k", + .owner = THIS_MODULE, + }, + .probe = bq32k_probe, + .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"); |