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-ds1347.c (4322B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/* rtc-ds1347.c
      3 *
      4 * Driver for Dallas Semiconductor DS1347 Low Current, SPI Compatible
      5 * Real Time Clock
      6 *
      7 * Author : Raghavendra Chandra Ganiga <ravi23ganiga@gmail.com>
      8 */
      9
     10#include <linux/init.h>
     11#include <linux/module.h>
     12#include <linux/device.h>
     13#include <linux/platform_device.h>
     14#include <linux/rtc.h>
     15#include <linux/spi/spi.h>
     16#include <linux/bcd.h>
     17#include <linux/regmap.h>
     18
     19/* Registers in ds1347 rtc */
     20
     21#define DS1347_SECONDS_REG	0x01
     22#define DS1347_MINUTES_REG	0x03
     23#define DS1347_HOURS_REG	0x05
     24#define DS1347_DATE_REG		0x07
     25#define DS1347_MONTH_REG	0x09
     26#define DS1347_DAY_REG		0x0B
     27#define DS1347_YEAR_REG		0x0D
     28#define DS1347_CONTROL_REG	0x0F
     29#define DS1347_CENTURY_REG	0x13
     30#define DS1347_STATUS_REG	0x17
     31#define DS1347_CLOCK_BURST	0x3F
     32
     33#define DS1347_WP_BIT		BIT(7)
     34
     35#define DS1347_NEOSC_BIT	BIT(7)
     36#define DS1347_OSF_BIT		BIT(2)
     37
     38static const struct regmap_range ds1347_ranges[] = {
     39	{
     40		.range_min = DS1347_SECONDS_REG,
     41		.range_max = DS1347_STATUS_REG,
     42	},
     43};
     44
     45static const struct regmap_access_table ds1347_access_table = {
     46	.yes_ranges = ds1347_ranges,
     47	.n_yes_ranges = ARRAY_SIZE(ds1347_ranges),
     48};
     49
     50static int ds1347_read_time(struct device *dev, struct rtc_time *dt)
     51{
     52	struct regmap *map = dev_get_drvdata(dev);
     53	unsigned int status, century, secs;
     54	unsigned char buf[8];
     55	int err;
     56
     57	err = regmap_read(map, DS1347_STATUS_REG, &status);
     58	if (err)
     59		return err;
     60
     61	if (status & DS1347_OSF_BIT)
     62		return -EINVAL;
     63
     64	do {
     65		err = regmap_bulk_read(map, DS1347_CLOCK_BURST, buf, 8);
     66		if (err)
     67			return err;
     68
     69		err = regmap_read(map, DS1347_CENTURY_REG, &century);
     70		if (err)
     71			return err;
     72
     73		err = regmap_read(map, DS1347_SECONDS_REG, &secs);
     74		if (err)
     75			return err;
     76	} while (buf[0] != secs);
     77
     78	dt->tm_sec = bcd2bin(buf[0]);
     79	dt->tm_min = bcd2bin(buf[1] & 0x7f);
     80	dt->tm_hour = bcd2bin(buf[2] & 0x3F);
     81	dt->tm_mday = bcd2bin(buf[3]);
     82	dt->tm_mon = bcd2bin(buf[4]) - 1;
     83	dt->tm_wday = bcd2bin(buf[5]) - 1;
     84	dt->tm_year = (bcd2bin(century) * 100) + bcd2bin(buf[6]) - 1900;
     85
     86	return 0;
     87}
     88
     89static int ds1347_set_time(struct device *dev, struct rtc_time *dt)
     90{
     91	struct regmap *map = dev_get_drvdata(dev);
     92	unsigned int century;
     93	unsigned char buf[8];
     94	int err;
     95
     96	err = regmap_update_bits(map, DS1347_STATUS_REG,
     97				 DS1347_NEOSC_BIT, DS1347_NEOSC_BIT);
     98	if (err)
     99		return err;
    100
    101	buf[0] = bin2bcd(dt->tm_sec);
    102	buf[1] = bin2bcd(dt->tm_min);
    103	buf[2] = (bin2bcd(dt->tm_hour) & 0x3F);
    104	buf[3] = bin2bcd(dt->tm_mday);
    105	buf[4] = bin2bcd(dt->tm_mon + 1);
    106	buf[5] = bin2bcd(dt->tm_wday + 1);
    107	buf[6] = bin2bcd(dt->tm_year % 100);
    108	buf[7] = bin2bcd(0x00);
    109
    110	err = regmap_bulk_write(map, DS1347_CLOCK_BURST, buf, 8);
    111	if (err)
    112		return err;
    113
    114	century = (dt->tm_year / 100) + 19;
    115	err = regmap_write(map, DS1347_CENTURY_REG, century);
    116	if (err)
    117		return err;
    118
    119	return regmap_update_bits(map, DS1347_STATUS_REG,
    120				  DS1347_NEOSC_BIT | DS1347_OSF_BIT, 0);
    121}
    122
    123static const struct rtc_class_ops ds1347_rtc_ops = {
    124	.read_time = ds1347_read_time,
    125	.set_time = ds1347_set_time,
    126};
    127
    128static int ds1347_probe(struct spi_device *spi)
    129{
    130	struct rtc_device *rtc;
    131	struct regmap_config config;
    132	struct regmap *map;
    133	int err;
    134
    135	memset(&config, 0, sizeof(config));
    136	config.reg_bits = 8;
    137	config.val_bits = 8;
    138	config.read_flag_mask = 0x80;
    139	config.max_register = 0x3F;
    140	config.wr_table = &ds1347_access_table;
    141
    142	/* spi setup with ds1347 in mode 3 and bits per word as 8 */
    143	spi->mode = SPI_MODE_3;
    144	spi->bits_per_word = 8;
    145	spi_setup(spi);
    146
    147	map = devm_regmap_init_spi(spi, &config);
    148
    149	if (IS_ERR(map)) {
    150		dev_err(&spi->dev, "ds1347 regmap init spi failed\n");
    151		return PTR_ERR(map);
    152	}
    153
    154	spi_set_drvdata(spi, map);
    155
    156	/* Disable the write protect of rtc */
    157	err = regmap_update_bits(map, DS1347_CONTROL_REG, DS1347_WP_BIT, 0);
    158	if (err)
    159		return err;
    160
    161	rtc = devm_rtc_allocate_device(&spi->dev);
    162	if (IS_ERR(rtc))
    163		return PTR_ERR(rtc);
    164
    165	rtc->ops = &ds1347_rtc_ops;
    166	rtc->range_min = RTC_TIMESTAMP_BEGIN_0000;
    167	rtc->range_max = RTC_TIMESTAMP_END_9999;
    168
    169	return devm_rtc_register_device(rtc);
    170}
    171
    172static struct spi_driver ds1347_driver = {
    173	.driver = {
    174		.name = "ds1347",
    175	},
    176	.probe = ds1347_probe,
    177};
    178
    179module_spi_driver(ds1347_driver);
    180
    181MODULE_DESCRIPTION("DS1347 SPI RTC DRIVER");
    182MODULE_AUTHOR("Raghavendra C Ganiga <ravi23ganiga@gmail.com>");
    183MODULE_LICENSE("GPL v2");