diff options
Diffstat (limited to 'drivers/rtc/rtc-pcf8523.c')
| -rw-r--r-- | drivers/rtc/rtc-pcf8523.c | 326 |
1 files changed, 326 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-pcf8523.c b/drivers/rtc/rtc-pcf8523.c new file mode 100644 index 000000000000..be05a645f99e --- /dev/null +++ b/drivers/rtc/rtc-pcf8523.c @@ -0,0 +1,326 @@ +/* + * Copyright (C) 2012 Avionic Design GmbH + * + * 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. + */ + +#include <linux/bcd.h> +#include <linux/i2c.h> +#include <linux/module.h> +#include <linux/rtc.h> +#include <linux/of.h> + +#define DRIVER_NAME "rtc-pcf8523" + +#define REG_CONTROL1 0x00 +#define REG_CONTROL1_CAP_SEL (1 << 7) +#define REG_CONTROL1_STOP (1 << 5) + +#define REG_CONTROL3 0x02 +#define REG_CONTROL3_PM_BLD (1 << 7) /* battery low detection disabled */ +#define REG_CONTROL3_PM_VDD (1 << 6) /* switch-over disabled */ +#define REG_CONTROL3_PM_DSM (1 << 5) /* direct switching mode */ +#define REG_CONTROL3_PM_MASK 0xe0 + +#define REG_SECONDS 0x03 +#define REG_SECONDS_OS (1 << 7) + +#define REG_MINUTES 0x04 +#define REG_HOURS 0x05 +#define REG_DAYS 0x06 +#define REG_WEEKDAYS 0x07 +#define REG_MONTHS 0x08 +#define REG_YEARS 0x09 + +struct pcf8523 { + struct rtc_device *rtc; +}; + +static int pcf8523_read(struct i2c_client *client, u8 reg, u8 *valuep) +{ + struct i2c_msg msgs[2]; + u8 value = 0; + int err; + + msgs[0].addr = client->addr; + msgs[0].flags = 0; + msgs[0].len = sizeof(reg); + msgs[0].buf = ® + + msgs[1].addr = client->addr; + msgs[1].flags = I2C_M_RD; + msgs[1].len = sizeof(value); + msgs[1].buf = &value; + + err = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs)); + if (err < 0) + return err; + + *valuep = value; + + return 0; +} + +static int pcf8523_write(struct i2c_client *client, u8 reg, u8 value) +{ + u8 buffer[2] = { reg, value }; + struct i2c_msg msg; + int err; + + msg.addr = client->addr; + msg.flags = 0; + msg.len = sizeof(buffer); + msg.buf = buffer; + + err = i2c_transfer(client->adapter, &msg, 1); + if (err < 0) + return err; + + return 0; +} + +static int pcf8523_select_capacitance(struct i2c_client *client, bool high) +{ + u8 value; + int err; + + err = pcf8523_read(client, REG_CONTROL1, &value); + if (err < 0) + return err; + + if (!high) + value &= ~REG_CONTROL1_CAP_SEL; + else + value |= REG_CONTROL1_CAP_SEL; + + err = pcf8523_write(client, REG_CONTROL1, value); + if (err < 0) + return err; + + return err; +} + +static int pcf8523_set_pm(struct i2c_client *client, u8 pm) +{ + u8 value; + int err; + + err = pcf8523_read(client, REG_CONTROL3, &value); + if (err < 0) + return err; + + value = (value & ~REG_CONTROL3_PM_MASK) | pm; + + err = pcf8523_write(client, REG_CONTROL3, value); + if (err < 0) + return err; + + return 0; +} + +static int pcf8523_stop_rtc(struct i2c_client *client) +{ + u8 value; + int err; + + err = pcf8523_read(client, REG_CONTROL1, &value); + if (err < 0) + return err; + + value |= REG_CONTROL1_STOP; + + err = pcf8523_write(client, REG_CONTROL1, value); + if (err < 0) + return err; + + return 0; +} + +static int pcf8523_start_rtc(struct i2c_client *client) +{ + u8 value; + int err; + + err = pcf8523_read(client, REG_CONTROL1, &value); + if (err < 0) + return err; + + value &= ~REG_CONTROL1_STOP; + + err = pcf8523_write(client, REG_CONTROL1, value); + if (err < 0) + return err; + + return 0; +} + +static int pcf8523_rtc_read_time(struct device *dev, struct rtc_time *tm) +{ + struct i2c_client *client = to_i2c_client(dev); + u8 start = REG_SECONDS, regs[7]; + struct i2c_msg msgs[2]; + int err; + + msgs[0].addr = client->addr; + msgs[0].flags = 0; + msgs[0].len = 1; + msgs[0].buf = &start; + + msgs[1].addr = client->addr; + msgs[1].flags = I2C_M_RD; + msgs[1].len = sizeof(regs); + msgs[1].buf = regs; + + err = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs)); + if (err < 0) + return err; + + if (regs[0] & REG_SECONDS_OS) { + /* + * If the oscillator was stopped, try to clear the flag. Upon + * power-up the flag is always set, but if we cannot clear it + * the oscillator isn't running properly for some reason. The + * sensible thing therefore is to return an error, signalling + * that the clock cannot be assumed to be correct. + */ + + regs[0] &= ~REG_SECONDS_OS; + + err = pcf8523_write(client, REG_SECONDS, regs[0]); + if (err < 0) + return err; + + err = pcf8523_read(client, REG_SECONDS, ®s[0]); + if (err < 0) + return err; + + if (regs[0] & REG_SECONDS_OS) + return -EAGAIN; + } + + tm->tm_sec = bcd2bin(regs[0] & 0x7f); + tm->tm_min = bcd2bin(regs[1] & 0x7f); + tm->tm_hour = bcd2bin(regs[2] & 0x3f); + tm->tm_mday = bcd2bin(regs[3] & 0x3f); + tm->tm_wday = regs[4] & 0x7; + tm->tm_mon = bcd2bin(regs[5] & 0x1f); + tm->tm_year = bcd2bin(regs[6]) + 100; + + return rtc_valid_tm(tm); +} + +static int pcf8523_rtc_set_time(struct device *dev, struct rtc_time *tm) +{ + struct i2c_client *client = to_i2c_client(dev); + struct i2c_msg msg; + u8 regs[8]; + int err; + + err = pcf8523_stop_rtc(client); + if (err < 0) + return err; + + regs[0] = REG_SECONDS; + regs[1] = bin2bcd(tm->tm_sec); + regs[2] = bin2bcd(tm->tm_min); + regs[3] = bin2bcd(tm->tm_hour); + regs[4] = bin2bcd(tm->tm_mday); + regs[5] = tm->tm_wday; + regs[6] = bin2bcd(tm->tm_mon); + regs[7] = bin2bcd(tm->tm_year - 100); + + msg.addr = client->addr; + msg.flags = 0; + msg.len = sizeof(regs); + msg.buf = regs; + + err = i2c_transfer(client->adapter, &msg, 1); + if (err < 0) { + /* + * If the time cannot be set, restart the RTC anyway. Note + * that errors are ignored if the RTC cannot be started so + * that we have a chance to propagate the original error. + */ + pcf8523_start_rtc(client); + return err; + } + + return pcf8523_start_rtc(client); +} + +static const struct rtc_class_ops pcf8523_rtc_ops = { + .read_time = pcf8523_rtc_read_time, + .set_time = pcf8523_rtc_set_time, +}; + +static int pcf8523_probe(struct i2c_client *client, + const struct i2c_device_id *id) +{ + struct pcf8523 *pcf; + int err; + + if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) + return -ENODEV; + + pcf = devm_kzalloc(&client->dev, sizeof(*pcf), GFP_KERNEL); + if (!pcf) + return -ENOMEM; + + err = pcf8523_select_capacitance(client, true); + if (err < 0) + return err; + + err = pcf8523_set_pm(client, 0); + if (err < 0) + return err; + + pcf->rtc = rtc_device_register(DRIVER_NAME, &client->dev, + &pcf8523_rtc_ops, THIS_MODULE); + if (IS_ERR(pcf->rtc)) + return PTR_ERR(pcf->rtc); + + i2c_set_clientdata(client, pcf); + + return 0; +} + +static int pcf8523_remove(struct i2c_client *client) +{ + struct pcf8523 *pcf = i2c_get_clientdata(client); + + rtc_device_unregister(pcf->rtc); + + return 0; +} + +static const struct i2c_device_id pcf8523_id[] = { + { "pcf8523", 0 }, + { } +}; +MODULE_DEVICE_TABLE(i2c, pcf8523_id); + +#ifdef CONFIG_OF +static const struct of_device_id pcf8523_of_match[] = { + { .compatible = "nxp,pcf8523" }, + { } +}; +MODULE_DEVICE_TABLE(of, pcf8523_of_match); +#endif + +static struct i2c_driver pcf8523_driver = { + .driver = { + .name = DRIVER_NAME, + .owner = THIS_MODULE, + .of_match_table = of_match_ptr(pcf8523_of_match), + }, + .probe = pcf8523_probe, + .remove = pcf8523_remove, + .id_table = pcf8523_id, +}; +module_i2c_driver(pcf8523_driver); + +MODULE_AUTHOR("Thierry Reding <thierry.reding@avionic-design.de>"); +MODULE_DESCRIPTION("NXP PCF8523 RTC driver"); +MODULE_LICENSE("GPL v2"); |
