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kernel-fxtec-pro1x/drivers/rtc/rtc-rs5c348.c
Alexandre Belloni bff11e3aa9 rtc: rs5c348: let the core handle invalid time 
Returning a valid time when the time is invalid is a bad practice, because
then userspace is not able to react on the information. Also, it doesn't
make sense to return epoch because it is already the default time.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
2018-03-01 10:49:40 +01:00

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/*
* A SPI driver for the Ricoh RS5C348 RTC
*
* Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* The board specific init code should provide characteristics of this
* device:
* Mode 1 (High-Active, Shift-Then-Sample), High Avtive CS
*/
#include <linux/bcd.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/rtc.h>
#include <linux/workqueue.h>
#include <linux/spi/spi.h>
#include <linux/module.h>
#define RS5C348_REG_SECS 0
#define RS5C348_REG_MINS 1
#define RS5C348_REG_HOURS 2
#define RS5C348_REG_WDAY 3
#define RS5C348_REG_DAY 4
#define RS5C348_REG_MONTH 5
#define RS5C348_REG_YEAR 6
#define RS5C348_REG_CTL1 14
#define RS5C348_REG_CTL2 15
#define RS5C348_SECS_MASK 0x7f
#define RS5C348_MINS_MASK 0x7f
#define RS5C348_HOURS_MASK 0x3f
#define RS5C348_WDAY_MASK 0x03
#define RS5C348_DAY_MASK 0x3f
#define RS5C348_MONTH_MASK 0x1f
#define RS5C348_BIT_PM 0x20 /* REG_HOURS */
#define RS5C348_BIT_Y2K 0x80 /* REG_MONTH */
#define RS5C348_BIT_24H 0x20 /* REG_CTL1 */
#define RS5C348_BIT_XSTP 0x10 /* REG_CTL2 */
#define RS5C348_BIT_VDET 0x40 /* REG_CTL2 */
#define RS5C348_CMD_W(addr) (((addr) << 4) | 0x08) /* single write */
#define RS5C348_CMD_R(addr) (((addr) << 4) | 0x0c) /* single read */
#define RS5C348_CMD_MW(addr) (((addr) << 4) | 0x00) /* burst write */
#define RS5C348_CMD_MR(addr) (((addr) << 4) | 0x04) /* burst read */
struct rs5c348_plat_data {
struct rtc_device *rtc;
int rtc_24h;
};
static int
rs5c348_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
struct spi_device *spi = to_spi_device(dev);
struct rs5c348_plat_data *pdata = dev_get_platdata(&spi->dev);
u8 txbuf[5+7], *txp;
int ret;
/* Transfer 5 bytes before writing SEC. This gives 31us for carry. */
txp = txbuf;
txbuf[0] = RS5C348_CMD_R(RS5C348_REG_CTL2); /* cmd, ctl2 */
txbuf[1] = 0; /* dummy */
txbuf[2] = RS5C348_CMD_R(RS5C348_REG_CTL2); /* cmd, ctl2 */
txbuf[3] = 0; /* dummy */
txbuf[4] = RS5C348_CMD_MW(RS5C348_REG_SECS); /* cmd, sec, ... */
txp = &txbuf[5];
txp[RS5C348_REG_SECS] = bin2bcd(tm->tm_sec);
txp[RS5C348_REG_MINS] = bin2bcd(tm->tm_min);
if (pdata->rtc_24h) {
txp[RS5C348_REG_HOURS] = bin2bcd(tm->tm_hour);
} else {
/* hour 0 is AM12, noon is PM12 */
txp[RS5C348_REG_HOURS] = bin2bcd((tm->tm_hour + 11) % 12 + 1) |
(tm->tm_hour >= 12 ? RS5C348_BIT_PM : 0);
}
txp[RS5C348_REG_WDAY] = bin2bcd(tm->tm_wday);
txp[RS5C348_REG_DAY] = bin2bcd(tm->tm_mday);
txp[RS5C348_REG_MONTH] = bin2bcd(tm->tm_mon + 1) |
(tm->tm_year >= 100 ? RS5C348_BIT_Y2K : 0);
txp[RS5C348_REG_YEAR] = bin2bcd(tm->tm_year % 100);
/* write in one transfer to avoid data inconsistency */
ret = spi_write_then_read(spi, txbuf, sizeof(txbuf), NULL, 0);
udelay(62); /* Tcsr 62us */
return ret;
}
static int
rs5c348_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
struct spi_device *spi = to_spi_device(dev);
struct rs5c348_plat_data *pdata = dev_get_platdata(&spi->dev);
u8 txbuf[5], rxbuf[7];
int ret;
/* Transfer 5 byte befores reading SEC. This gives 31us for carry. */
txbuf[0] = RS5C348_CMD_R(RS5C348_REG_CTL2); /* cmd, ctl2 */
txbuf[1] = 0; /* dummy */
txbuf[2] = RS5C348_CMD_R(RS5C348_REG_CTL2); /* cmd, ctl2 */
txbuf[3] = 0; /* dummy */
txbuf[4] = RS5C348_CMD_MR(RS5C348_REG_SECS); /* cmd, sec, ... */
/* read in one transfer to avoid data inconsistency */
ret = spi_write_then_read(spi, txbuf, sizeof(txbuf),
rxbuf, sizeof(rxbuf));
udelay(62); /* Tcsr 62us */
if (ret < 0)
return ret;
tm->tm_sec = bcd2bin(rxbuf[RS5C348_REG_SECS] & RS5C348_SECS_MASK);
tm->tm_min = bcd2bin(rxbuf[RS5C348_REG_MINS] & RS5C348_MINS_MASK);
tm->tm_hour = bcd2bin(rxbuf[RS5C348_REG_HOURS] & RS5C348_HOURS_MASK);
if (!pdata->rtc_24h) {
if (rxbuf[RS5C348_REG_HOURS] & RS5C348_BIT_PM) {
tm->tm_hour -= 20;
tm->tm_hour %= 12;
tm->tm_hour += 12;
} else
tm->tm_hour %= 12;
}
tm->tm_wday = bcd2bin(rxbuf[RS5C348_REG_WDAY] & RS5C348_WDAY_MASK);
tm->tm_mday = bcd2bin(rxbuf[RS5C348_REG_DAY] & RS5C348_DAY_MASK);
tm->tm_mon =
bcd2bin(rxbuf[RS5C348_REG_MONTH] & RS5C348_MONTH_MASK) - 1;
/* year is 1900 + tm->tm_year */
tm->tm_year = bcd2bin(rxbuf[RS5C348_REG_YEAR]) +
((rxbuf[RS5C348_REG_MONTH] & RS5C348_BIT_Y2K) ? 100 : 0);
return 0;
}
static const struct rtc_class_ops rs5c348_rtc_ops = {
.read_time = rs5c348_rtc_read_time,
.set_time = rs5c348_rtc_set_time,
};
static struct spi_driver rs5c348_driver;
static int rs5c348_probe(struct spi_device *spi)
{
int ret;
struct rtc_device *rtc;
struct rs5c348_plat_data *pdata;
pdata = devm_kzalloc(&spi->dev, sizeof(struct rs5c348_plat_data),
GFP_KERNEL);
if (!pdata)
return -ENOMEM;
spi->dev.platform_data = pdata;
/* Check D7 of SECOND register */
ret = spi_w8r8(spi, RS5C348_CMD_R(RS5C348_REG_SECS));
if (ret < 0 || (ret & 0x80)) {
dev_err(&spi->dev, "not found.\n");
goto kfree_exit;
}
dev_info(&spi->dev, "spiclk %u KHz.\n",
(spi->max_speed_hz + 500) / 1000);
/* turn RTC on if it was not on */
ret = spi_w8r8(spi, RS5C348_CMD_R(RS5C348_REG_CTL2));
if (ret < 0)
goto kfree_exit;
if (ret & (RS5C348_BIT_XSTP | RS5C348_BIT_VDET)) {
u8 buf[2];
struct rtc_time tm;
if (ret & RS5C348_BIT_VDET)
dev_warn(&spi->dev, "voltage-low detected.\n");
if (ret & RS5C348_BIT_XSTP)
dev_warn(&spi->dev, "oscillator-stop detected.\n");
rtc_time_to_tm(0, &tm); /* 1970/1/1 */
ret = rs5c348_rtc_set_time(&spi->dev, &tm);
if (ret < 0)
goto kfree_exit;
buf[0] = RS5C348_CMD_W(RS5C348_REG_CTL2);
buf[1] = 0;
ret = spi_write_then_read(spi, buf, sizeof(buf), NULL, 0);
if (ret < 0)
goto kfree_exit;
}
ret = spi_w8r8(spi, RS5C348_CMD_R(RS5C348_REG_CTL1));
if (ret < 0)
goto kfree_exit;
if (ret & RS5C348_BIT_24H)
pdata->rtc_24h = 1;
rtc = devm_rtc_device_register(&spi->dev, rs5c348_driver.driver.name,
&rs5c348_rtc_ops, THIS_MODULE);
if (IS_ERR(rtc)) {
ret = PTR_ERR(rtc);
goto kfree_exit;
}
pdata->rtc = rtc;
return 0;
kfree_exit:
return ret;
}
static struct spi_driver rs5c348_driver = {
.driver = {
.name = "rtc-rs5c348",
},
.probe = rs5c348_probe,
};
module_spi_driver(rs5c348_driver);
MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
MODULE_DESCRIPTION("Ricoh RS5C348 RTC driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("spi:rtc-rs5c348");
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