diff options
Diffstat (limited to 'kernel/drivers/rtc/rtc-r9701.c')
| -rw-r--r-- | kernel/drivers/rtc/rtc-r9701.c | 186 |
1 files changed, 186 insertions, 0 deletions
diff --git a/kernel/drivers/rtc/rtc-r9701.c b/kernel/drivers/rtc/rtc-r9701.c new file mode 100644 index 000000000..feeedbd82 --- /dev/null +++ b/kernel/drivers/rtc/rtc-r9701.c @@ -0,0 +1,186 @@ +/* + * Driver for Epson RTC-9701JE + * + * Copyright (C) 2008 Magnus Damm + * + * Based on rtc-max6902.c + * + * Copyright (C) 2006 8D Technologies inc. + * Copyright (C) 2004 Compulab Ltd. + * + * 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/module.h> +#include <linux/kernel.h> +#include <linux/platform_device.h> +#include <linux/device.h> +#include <linux/init.h> +#include <linux/rtc.h> +#include <linux/spi/spi.h> +#include <linux/bcd.h> +#include <linux/delay.h> +#include <linux/bitops.h> + +#define RSECCNT 0x00 /* Second Counter */ +#define RMINCNT 0x01 /* Minute Counter */ +#define RHRCNT 0x02 /* Hour Counter */ +#define RWKCNT 0x03 /* Week Counter */ +#define RDAYCNT 0x04 /* Day Counter */ +#define RMONCNT 0x05 /* Month Counter */ +#define RYRCNT 0x06 /* Year Counter */ +#define R100CNT 0x07 /* Y100 Counter */ +#define RMINAR 0x08 /* Minute Alarm */ +#define RHRAR 0x09 /* Hour Alarm */ +#define RWKAR 0x0a /* Week/Day Alarm */ +#define RTIMCNT 0x0c /* Interval Timer */ +#define REXT 0x0d /* Extension Register */ +#define RFLAG 0x0e /* RTC Flag Register */ +#define RCR 0x0f /* RTC Control Register */ + +static int write_reg(struct device *dev, int address, unsigned char data) +{ + struct spi_device *spi = to_spi_device(dev); + unsigned char buf[2]; + + buf[0] = address & 0x7f; + buf[1] = data; + + return spi_write(spi, buf, ARRAY_SIZE(buf)); +} + +static int read_regs(struct device *dev, unsigned char *regs, int no_regs) +{ + struct spi_device *spi = to_spi_device(dev); + u8 txbuf[1], rxbuf[1]; + int k, ret; + + ret = 0; + + for (k = 0; ret == 0 && k < no_regs; k++) { + txbuf[0] = 0x80 | regs[k]; + ret = spi_write_then_read(spi, txbuf, 1, rxbuf, 1); + regs[k] = rxbuf[0]; + } + + return ret; +} + +static int r9701_get_datetime(struct device *dev, struct rtc_time *dt) +{ + int ret; + unsigned char buf[] = { RSECCNT, RMINCNT, RHRCNT, + RDAYCNT, RMONCNT, RYRCNT }; + + ret = read_regs(dev, buf, ARRAY_SIZE(buf)); + if (ret) + return ret; + + memset(dt, 0, sizeof(*dt)); + + dt->tm_sec = bcd2bin(buf[0]); /* RSECCNT */ + dt->tm_min = bcd2bin(buf[1]); /* RMINCNT */ + dt->tm_hour = bcd2bin(buf[2]); /* RHRCNT */ + + dt->tm_mday = bcd2bin(buf[3]); /* RDAYCNT */ + dt->tm_mon = bcd2bin(buf[4]) - 1; /* RMONCNT */ + dt->tm_year = bcd2bin(buf[5]) + 100; /* RYRCNT */ + + /* the rtc device may contain illegal values on power up + * according to the data sheet. make sure they are valid. + */ + + return rtc_valid_tm(dt); +} + +static int r9701_set_datetime(struct device *dev, struct rtc_time *dt) +{ + int ret, year; + + year = dt->tm_year + 1900; + if (year >= 2100 || year < 2000) + return -EINVAL; + + ret = write_reg(dev, RHRCNT, bin2bcd(dt->tm_hour)); + ret = ret ? ret : write_reg(dev, RMINCNT, bin2bcd(dt->tm_min)); + ret = ret ? ret : write_reg(dev, RSECCNT, bin2bcd(dt->tm_sec)); + ret = ret ? ret : write_reg(dev, RDAYCNT, bin2bcd(dt->tm_mday)); + ret = ret ? ret : write_reg(dev, RMONCNT, bin2bcd(dt->tm_mon + 1)); + ret = ret ? ret : write_reg(dev, RYRCNT, bin2bcd(dt->tm_year - 100)); + ret = ret ? ret : write_reg(dev, RWKCNT, 1 << dt->tm_wday); + + return ret; +} + +static const struct rtc_class_ops r9701_rtc_ops = { + .read_time = r9701_get_datetime, + .set_time = r9701_set_datetime, +}; + +static int r9701_probe(struct spi_device *spi) +{ + struct rtc_device *rtc; + struct rtc_time dt; + unsigned char tmp; + int res; + + tmp = R100CNT; + res = read_regs(&spi->dev, &tmp, 1); + if (res || tmp != 0x20) { + dev_err(&spi->dev, "cannot read RTC register\n"); + return -ENODEV; + } + + /* + * The device seems to be present. Now check if the registers + * contain invalid values. If so, try to write a default date: + * 2000/1/1 00:00:00 + */ + if (r9701_get_datetime(&spi->dev, &dt)) { + dev_info(&spi->dev, "trying to repair invalid date/time\n"); + dt.tm_sec = 0; + dt.tm_min = 0; + dt.tm_hour = 0; + dt.tm_mday = 1; + dt.tm_mon = 0; + dt.tm_year = 100; + + if (r9701_set_datetime(&spi->dev, &dt) || + r9701_get_datetime(&spi->dev, &dt)) { + dev_err(&spi->dev, "cannot repair RTC register\n"); + return -ENODEV; + } + } + + rtc = devm_rtc_device_register(&spi->dev, "r9701", + &r9701_rtc_ops, THIS_MODULE); + if (IS_ERR(rtc)) + return PTR_ERR(rtc); + + spi_set_drvdata(spi, rtc); + + return 0; +} + +static int r9701_remove(struct spi_device *spi) +{ + return 0; +} + +static struct spi_driver r9701_driver = { + .driver = { + .name = "rtc-r9701", + .owner = THIS_MODULE, + }, + .probe = r9701_probe, + .remove = r9701_remove, +}; + +module_spi_driver(r9701_driver); + +MODULE_DESCRIPTION("r9701 spi RTC driver"); +MODULE_AUTHOR("Magnus Damm <damm@opensource.se>"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("spi:rtc-r9701"); |