cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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rtc-ds1742.c (5921B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * An rtc driver for the Dallas DS1742
      4 *
      5 * Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
      6 *
      7 * Copyright (C) 2006 Torsten Ertbjerg Rasmussen <tr@newtec.dk>
      8 *  - nvram size determined from resource
      9 *  - this ds1742 driver now supports ds1743.
     10 */
     11
     12#include <linux/bcd.h>
     13#include <linux/kernel.h>
     14#include <linux/gfp.h>
     15#include <linux/delay.h>
     16#include <linux/jiffies.h>
     17#include <linux/rtc.h>
     18#include <linux/of.h>
     19#include <linux/of_device.h>
     20#include <linux/platform_device.h>
     21#include <linux/io.h>
     22#include <linux/module.h>
     23
     24#define RTC_SIZE		8
     25
     26#define RTC_CONTROL		0
     27#define RTC_CENTURY		0
     28#define RTC_SECONDS		1
     29#define RTC_MINUTES		2
     30#define RTC_HOURS		3
     31#define RTC_DAY			4
     32#define RTC_DATE		5
     33#define RTC_MONTH		6
     34#define RTC_YEAR		7
     35
     36#define RTC_CENTURY_MASK	0x3f
     37#define RTC_SECONDS_MASK	0x7f
     38#define RTC_DAY_MASK		0x07
     39
     40/* Bits in the Control/Century register */
     41#define RTC_WRITE		0x80
     42#define RTC_READ		0x40
     43
     44/* Bits in the Seconds register */
     45#define RTC_STOP		0x80
     46
     47/* Bits in the Day register */
     48#define RTC_BATT_FLAG		0x80
     49
     50struct rtc_plat_data {
     51	void __iomem *ioaddr_nvram;
     52	void __iomem *ioaddr_rtc;
     53	unsigned long last_jiffies;
     54};
     55
     56static int ds1742_rtc_set_time(struct device *dev, struct rtc_time *tm)
     57{
     58	struct rtc_plat_data *pdata = dev_get_drvdata(dev);
     59	void __iomem *ioaddr = pdata->ioaddr_rtc;
     60	u8 century;
     61
     62	century = bin2bcd((tm->tm_year + 1900) / 100);
     63
     64	writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
     65
     66	writeb(bin2bcd(tm->tm_year % 100), ioaddr + RTC_YEAR);
     67	writeb(bin2bcd(tm->tm_mon + 1), ioaddr + RTC_MONTH);
     68	writeb(bin2bcd(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY);
     69	writeb(bin2bcd(tm->tm_mday), ioaddr + RTC_DATE);
     70	writeb(bin2bcd(tm->tm_hour), ioaddr + RTC_HOURS);
     71	writeb(bin2bcd(tm->tm_min), ioaddr + RTC_MINUTES);
     72	writeb(bin2bcd(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS);
     73
     74	/* RTC_CENTURY and RTC_CONTROL share same register */
     75	writeb(RTC_WRITE | (century & RTC_CENTURY_MASK), ioaddr + RTC_CENTURY);
     76	writeb(century & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
     77	return 0;
     78}
     79
     80static int ds1742_rtc_read_time(struct device *dev, struct rtc_time *tm)
     81{
     82	struct rtc_plat_data *pdata = dev_get_drvdata(dev);
     83	void __iomem *ioaddr = pdata->ioaddr_rtc;
     84	unsigned int year, month, day, hour, minute, second, week;
     85	unsigned int century;
     86
     87	/* give enough time to update RTC in case of continuous read */
     88	if (pdata->last_jiffies == jiffies)
     89		msleep(1);
     90	pdata->last_jiffies = jiffies;
     91	writeb(RTC_READ, ioaddr + RTC_CONTROL);
     92	second = readb(ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK;
     93	minute = readb(ioaddr + RTC_MINUTES);
     94	hour = readb(ioaddr + RTC_HOURS);
     95	day = readb(ioaddr + RTC_DATE);
     96	week = readb(ioaddr + RTC_DAY) & RTC_DAY_MASK;
     97	month = readb(ioaddr + RTC_MONTH);
     98	year = readb(ioaddr + RTC_YEAR);
     99	century = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
    100	writeb(0, ioaddr + RTC_CONTROL);
    101	tm->tm_sec = bcd2bin(second);
    102	tm->tm_min = bcd2bin(minute);
    103	tm->tm_hour = bcd2bin(hour);
    104	tm->tm_mday = bcd2bin(day);
    105	tm->tm_wday = bcd2bin(week);
    106	tm->tm_mon = bcd2bin(month) - 1;
    107	/* year is 1900 + tm->tm_year */
    108	tm->tm_year = bcd2bin(year) + bcd2bin(century) * 100 - 1900;
    109
    110	return 0;
    111}
    112
    113static const struct rtc_class_ops ds1742_rtc_ops = {
    114	.read_time	= ds1742_rtc_read_time,
    115	.set_time	= ds1742_rtc_set_time,
    116};
    117
    118static int ds1742_nvram_read(void *priv, unsigned int pos, void *val,
    119			     size_t bytes)
    120{
    121	struct rtc_plat_data *pdata = priv;
    122	void __iomem *ioaddr = pdata->ioaddr_nvram;
    123	u8 *buf = val;
    124
    125	for (; bytes; bytes--)
    126		*buf++ = readb(ioaddr + pos++);
    127	return 0;
    128}
    129
    130static int ds1742_nvram_write(void *priv, unsigned int pos, void *val,
    131			      size_t bytes)
    132{
    133	struct rtc_plat_data *pdata = priv;
    134	void __iomem *ioaddr = pdata->ioaddr_nvram;
    135	u8 *buf = val;
    136
    137	for (; bytes; bytes--)
    138		writeb(*buf++, ioaddr + pos++);
    139	return 0;
    140}
    141
    142static int ds1742_rtc_probe(struct platform_device *pdev)
    143{
    144	struct rtc_device *rtc;
    145	struct resource *res;
    146	unsigned int cen, sec;
    147	struct rtc_plat_data *pdata;
    148	void __iomem *ioaddr;
    149	int ret = 0;
    150	struct nvmem_config nvmem_cfg = {
    151		.name = "ds1742_nvram",
    152		.reg_read = ds1742_nvram_read,
    153		.reg_write = ds1742_nvram_write,
    154	};
    155
    156
    157	pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
    158	if (!pdata)
    159		return -ENOMEM;
    160
    161	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    162	ioaddr = devm_ioremap_resource(&pdev->dev, res);
    163	if (IS_ERR(ioaddr))
    164		return PTR_ERR(ioaddr);
    165
    166	pdata->ioaddr_nvram = ioaddr;
    167	pdata->ioaddr_rtc = ioaddr + resource_size(res) - RTC_SIZE;
    168
    169	nvmem_cfg.size = resource_size(res) - RTC_SIZE;
    170	nvmem_cfg.priv = pdata;
    171
    172	/* turn RTC on if it was not on */
    173	ioaddr = pdata->ioaddr_rtc;
    174	sec = readb(ioaddr + RTC_SECONDS);
    175	if (sec & RTC_STOP) {
    176		sec &= RTC_SECONDS_MASK;
    177		cen = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
    178		writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
    179		writeb(sec, ioaddr + RTC_SECONDS);
    180		writeb(cen & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
    181	}
    182	if (!(readb(ioaddr + RTC_DAY) & RTC_BATT_FLAG))
    183		dev_warn(&pdev->dev, "voltage-low detected.\n");
    184
    185	pdata->last_jiffies = jiffies;
    186	platform_set_drvdata(pdev, pdata);
    187
    188	rtc = devm_rtc_allocate_device(&pdev->dev);
    189	if (IS_ERR(rtc))
    190		return PTR_ERR(rtc);
    191
    192	rtc->ops = &ds1742_rtc_ops;
    193
    194	ret = devm_rtc_register_device(rtc);
    195	if (ret)
    196		return ret;
    197
    198	devm_rtc_nvmem_register(rtc, &nvmem_cfg);
    199
    200	return 0;
    201}
    202
    203static const struct of_device_id __maybe_unused ds1742_rtc_of_match[] = {
    204	{ .compatible = "maxim,ds1742", },
    205	{ }
    206};
    207MODULE_DEVICE_TABLE(of, ds1742_rtc_of_match);
    208
    209static struct platform_driver ds1742_rtc_driver = {
    210	.probe		= ds1742_rtc_probe,
    211	.driver		= {
    212		.name	= "rtc-ds1742",
    213		.of_match_table = of_match_ptr(ds1742_rtc_of_match),
    214	},
    215};
    216
    217module_platform_driver(ds1742_rtc_driver);
    218
    219MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
    220MODULE_DESCRIPTION("Dallas DS1742 RTC driver");
    221MODULE_LICENSE("GPL");
    222MODULE_ALIAS("platform:rtc-ds1742");