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