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-r9701.c (3649B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * Driver for Epson RTC-9701JE
      4 *
      5 * Copyright (C) 2008 Magnus Damm
      6 *
      7 * Based on rtc-max6902.c
      8 *
      9 * Copyright (C) 2006 8D Technologies inc.
     10 * Copyright (C) 2004 Compulab Ltd.
     11 */
     12
     13#include <linux/module.h>
     14#include <linux/kernel.h>
     15#include <linux/platform_device.h>
     16#include <linux/device.h>
     17#include <linux/init.h>
     18#include <linux/rtc.h>
     19#include <linux/spi/spi.h>
     20#include <linux/bcd.h>
     21#include <linux/delay.h>
     22#include <linux/bitops.h>
     23
     24#define RSECCNT	0x00	/* Second Counter */
     25#define RMINCNT	0x01	/* Minute Counter */
     26#define RHRCNT	0x02	/* Hour Counter */
     27#define RWKCNT	0x03	/* Week Counter */
     28#define RDAYCNT	0x04	/* Day Counter */
     29#define RMONCNT	0x05	/* Month Counter */
     30#define RYRCNT	0x06	/* Year Counter */
     31#define R100CNT	0x07	/* Y100 Counter */
     32#define RMINAR	0x08	/* Minute Alarm */
     33#define RHRAR	0x09	/* Hour Alarm */
     34#define RWKAR	0x0a	/* Week/Day Alarm */
     35#define RTIMCNT	0x0c	/* Interval Timer */
     36#define REXT	0x0d	/* Extension Register */
     37#define RFLAG	0x0e	/* RTC Flag Register */
     38#define RCR	0x0f	/* RTC Control Register */
     39
     40static int write_reg(struct device *dev, int address, unsigned char data)
     41{
     42	struct spi_device *spi = to_spi_device(dev);
     43	unsigned char buf[2];
     44
     45	buf[0] = address & 0x7f;
     46	buf[1] = data;
     47
     48	return spi_write(spi, buf, ARRAY_SIZE(buf));
     49}
     50
     51static int read_regs(struct device *dev, unsigned char *regs, int no_regs)
     52{
     53	struct spi_device *spi = to_spi_device(dev);
     54	u8 txbuf[1], rxbuf[1];
     55	int k, ret;
     56
     57	ret = 0;
     58
     59	for (k = 0; ret == 0 && k < no_regs; k++) {
     60		txbuf[0] = 0x80 | regs[k];
     61		ret = spi_write_then_read(spi, txbuf, 1, rxbuf, 1);
     62		regs[k] = rxbuf[0];
     63	}
     64
     65	return ret;
     66}
     67
     68static int r9701_get_datetime(struct device *dev, struct rtc_time *dt)
     69{
     70	int ret;
     71	unsigned char buf[] = { RSECCNT, RMINCNT, RHRCNT,
     72				RDAYCNT, RMONCNT, RYRCNT };
     73
     74	ret = read_regs(dev, buf, ARRAY_SIZE(buf));
     75	if (ret)
     76		return ret;
     77
     78	dt->tm_sec = bcd2bin(buf[0]); /* RSECCNT */
     79	dt->tm_min = bcd2bin(buf[1]); /* RMINCNT */
     80	dt->tm_hour = bcd2bin(buf[2]); /* RHRCNT */
     81
     82	dt->tm_mday = bcd2bin(buf[3]); /* RDAYCNT */
     83	dt->tm_mon = bcd2bin(buf[4]) - 1; /* RMONCNT */
     84	dt->tm_year = bcd2bin(buf[5]) + 100; /* RYRCNT */
     85
     86	return 0;
     87}
     88
     89static int r9701_set_datetime(struct device *dev, struct rtc_time *dt)
     90{
     91	int ret;
     92
     93	ret = write_reg(dev, RHRCNT, bin2bcd(dt->tm_hour));
     94	ret = ret ? ret : write_reg(dev, RMINCNT, bin2bcd(dt->tm_min));
     95	ret = ret ? ret : write_reg(dev, RSECCNT, bin2bcd(dt->tm_sec));
     96	ret = ret ? ret : write_reg(dev, RDAYCNT, bin2bcd(dt->tm_mday));
     97	ret = ret ? ret : write_reg(dev, RMONCNT, bin2bcd(dt->tm_mon + 1));
     98	ret = ret ? ret : write_reg(dev, RYRCNT, bin2bcd(dt->tm_year - 100));
     99
    100	return ret;
    101}
    102
    103static const struct rtc_class_ops r9701_rtc_ops = {
    104	.read_time	= r9701_get_datetime,
    105	.set_time	= r9701_set_datetime,
    106};
    107
    108static int r9701_probe(struct spi_device *spi)
    109{
    110	struct rtc_device *rtc;
    111	unsigned char tmp;
    112	int res;
    113
    114	tmp = R100CNT;
    115	res = read_regs(&spi->dev, &tmp, 1);
    116	if (res || tmp != 0x20) {
    117		dev_err(&spi->dev, "cannot read RTC register\n");
    118		return -ENODEV;
    119	}
    120
    121	rtc = devm_rtc_allocate_device(&spi->dev);
    122	if (IS_ERR(rtc))
    123		return PTR_ERR(rtc);
    124
    125	spi_set_drvdata(spi, rtc);
    126	rtc->ops = &r9701_rtc_ops;
    127	rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
    128	rtc->range_max = RTC_TIMESTAMP_END_2099;
    129
    130	return devm_rtc_register_device(rtc);
    131}
    132
    133static struct spi_driver r9701_driver = {
    134	.driver = {
    135		.name	= "rtc-r9701",
    136	},
    137	.probe	= r9701_probe,
    138};
    139
    140module_spi_driver(r9701_driver);
    141
    142MODULE_DESCRIPTION("r9701 spi RTC driver");
    143MODULE_AUTHOR("Magnus Damm <damm@opensource.se>");
    144MODULE_LICENSE("GPL");
    145MODULE_ALIAS("spi:rtc-r9701");