diff options
Diffstat (limited to 'drivers/rtc/rtc-ds1742.c')
| -rw-r--r-- | drivers/rtc/rtc-ds1742.c | 222 |
1 files changed, 222 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-ds1742.c b/drivers/rtc/rtc-ds1742.c new file mode 100644 index 000000000..13d45c697 --- /dev/null +++ b/drivers/rtc/rtc-ds1742.c @@ -0,0 +1,222 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * An rtc driver for the Dallas DS1742 + * + * Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp> + * + * Copyright (C) 2006 Torsten Ertbjerg Rasmussen <tr@newtec.dk> + * - nvram size determined from resource + * - this ds1742 driver now supports ds1743. + */ + +#include <linux/bcd.h> +#include <linux/kernel.h> +#include <linux/gfp.h> +#include <linux/delay.h> +#include <linux/jiffies.h> +#include <linux/rtc.h> +#include <linux/of.h> +#include <linux/of_device.h> +#include <linux/platform_device.h> +#include <linux/io.h> +#include <linux/module.h> + +#define RTC_SIZE 8 + +#define RTC_CONTROL 0 +#define RTC_CENTURY 0 +#define RTC_SECONDS 1 +#define RTC_MINUTES 2 +#define RTC_HOURS 3 +#define RTC_DAY 4 +#define RTC_DATE 5 +#define RTC_MONTH 6 +#define RTC_YEAR 7 + +#define RTC_CENTURY_MASK 0x3f +#define RTC_SECONDS_MASK 0x7f +#define RTC_DAY_MASK 0x07 + +/* Bits in the Control/Century register */ +#define RTC_WRITE 0x80 +#define RTC_READ 0x40 + +/* Bits in the Seconds register */ +#define RTC_STOP 0x80 + +/* Bits in the Day register */ +#define RTC_BATT_FLAG 0x80 + +struct rtc_plat_data { + void __iomem *ioaddr_nvram; + void __iomem *ioaddr_rtc; + unsigned long last_jiffies; +}; + +static int ds1742_rtc_set_time(struct device *dev, struct rtc_time *tm) +{ + struct rtc_plat_data *pdata = dev_get_drvdata(dev); + void __iomem *ioaddr = pdata->ioaddr_rtc; + u8 century; + + century = bin2bcd((tm->tm_year + 1900) / 100); + + writeb(RTC_WRITE, ioaddr + RTC_CONTROL); + + writeb(bin2bcd(tm->tm_year % 100), ioaddr + RTC_YEAR); + writeb(bin2bcd(tm->tm_mon + 1), ioaddr + RTC_MONTH); + writeb(bin2bcd(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY); + writeb(bin2bcd(tm->tm_mday), ioaddr + RTC_DATE); + writeb(bin2bcd(tm->tm_hour), ioaddr + RTC_HOURS); + writeb(bin2bcd(tm->tm_min), ioaddr + RTC_MINUTES); + writeb(bin2bcd(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS); + + /* RTC_CENTURY and RTC_CONTROL share same register */ + writeb(RTC_WRITE | (century & RTC_CENTURY_MASK), ioaddr + RTC_CENTURY); + writeb(century & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL); + return 0; +} + +static int ds1742_rtc_read_time(struct device *dev, struct rtc_time *tm) +{ + struct rtc_plat_data *pdata = dev_get_drvdata(dev); + void __iomem *ioaddr = pdata->ioaddr_rtc; + unsigned int year, month, day, hour, minute, second, week; + unsigned int century; + + /* give enough time to update RTC in case of continuous read */ + if (pdata->last_jiffies == jiffies) + msleep(1); + pdata->last_jiffies = jiffies; + writeb(RTC_READ, ioaddr + RTC_CONTROL); + second = readb(ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK; + minute = readb(ioaddr + RTC_MINUTES); + hour = readb(ioaddr + RTC_HOURS); + day = readb(ioaddr + RTC_DATE); + week = readb(ioaddr + RTC_DAY) & RTC_DAY_MASK; + month = readb(ioaddr + RTC_MONTH); + year = readb(ioaddr + RTC_YEAR); + century = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK; + writeb(0, ioaddr + RTC_CONTROL); + tm->tm_sec = bcd2bin(second); + tm->tm_min = bcd2bin(minute); + tm->tm_hour = bcd2bin(hour); + tm->tm_mday = bcd2bin(day); + tm->tm_wday = bcd2bin(week); + tm->tm_mon = bcd2bin(month) - 1; + /* year is 1900 + tm->tm_year */ + tm->tm_year = bcd2bin(year) + bcd2bin(century) * 100 - 1900; + + return 0; +} + +static const struct rtc_class_ops ds1742_rtc_ops = { + .read_time = ds1742_rtc_read_time, + .set_time = ds1742_rtc_set_time, +}; + +static int ds1742_nvram_read(void *priv, unsigned int pos, void *val, + size_t bytes) +{ + struct rtc_plat_data *pdata = priv; + void __iomem *ioaddr = pdata->ioaddr_nvram; + u8 *buf = val; + + for (; bytes; bytes--) + *buf++ = readb(ioaddr + pos++); + return 0; +} + +static int ds1742_nvram_write(void *priv, unsigned int pos, void *val, + size_t bytes) +{ + struct rtc_plat_data *pdata = priv; + void __iomem *ioaddr = pdata->ioaddr_nvram; + u8 *buf = val; + + for (; bytes; bytes--) + writeb(*buf++, ioaddr + pos++); + return 0; +} + +static int ds1742_rtc_probe(struct platform_device *pdev) +{ + struct rtc_device *rtc; + struct resource *res; + unsigned int cen, sec; + struct rtc_plat_data *pdata; + void __iomem *ioaddr; + int ret = 0; + struct nvmem_config nvmem_cfg = { + .name = "ds1742_nvram", + .reg_read = ds1742_nvram_read, + .reg_write = ds1742_nvram_write, + }; + + + pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL); + if (!pdata) + return -ENOMEM; + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + ioaddr = devm_ioremap_resource(&pdev->dev, res); + if (IS_ERR(ioaddr)) + return PTR_ERR(ioaddr); + + pdata->ioaddr_nvram = ioaddr; + pdata->ioaddr_rtc = ioaddr + resource_size(res) - RTC_SIZE; + + nvmem_cfg.size = resource_size(res) - RTC_SIZE; + nvmem_cfg.priv = pdata; + + /* turn RTC on if it was not on */ + ioaddr = pdata->ioaddr_rtc; + sec = readb(ioaddr + RTC_SECONDS); + if (sec & RTC_STOP) { + sec &= RTC_SECONDS_MASK; + cen = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK; + writeb(RTC_WRITE, ioaddr + RTC_CONTROL); + writeb(sec, ioaddr + RTC_SECONDS); + writeb(cen & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL); + } + if (!(readb(ioaddr + RTC_DAY) & RTC_BATT_FLAG)) + dev_warn(&pdev->dev, "voltage-low detected.\n"); + + pdata->last_jiffies = jiffies; + platform_set_drvdata(pdev, pdata); + + rtc = devm_rtc_allocate_device(&pdev->dev); + if (IS_ERR(rtc)) + return PTR_ERR(rtc); + + rtc->ops = &ds1742_rtc_ops; + + ret = devm_rtc_register_device(rtc); + if (ret) + return ret; + + devm_rtc_nvmem_register(rtc, &nvmem_cfg); + + return 0; +} + +static const struct of_device_id __maybe_unused ds1742_rtc_of_match[] = { + { .compatible = "maxim,ds1742", }, + { } +}; +MODULE_DEVICE_TABLE(of, ds1742_rtc_of_match); + +static struct platform_driver ds1742_rtc_driver = { + .probe = ds1742_rtc_probe, + .driver = { + .name = "rtc-ds1742", + .of_match_table = of_match_ptr(ds1742_rtc_of_match), + }, +}; + +module_platform_driver(ds1742_rtc_driver); + +MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>"); +MODULE_DESCRIPTION("Dallas DS1742 RTC driver"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("platform:rtc-ds1742"); |