Minki/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2024-09-20 15:03:04 +00:00
Code Issues Packages Projects Releases Wiki Activity
3ea07127d9
linux/drivers/rtc/rtc-m48t86.c
H Hartley Sweeten 3ea07127d9 rtc: m48t86: verify that the RTC is actually present 
The RTC is an optional feature at purchase time on some Technologic
Systems boards. Verify that it actually exists by checking if the
last two bytes of the NVRAM can be changed.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
2017-02-21 18:16:31 +01:00

306 lines
8.2 KiB
C
Raw Blame History

/*
* ST M48T86 / Dallas DS12887 RTC driver
* Copyright (c) 2006 Tower Technologies
*
* Author: Alessandro Zummo <a.zummo@towertech.it>
*
* 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.
*
* This drivers only supports the clock running in BCD and 24H mode.
* If it will be ever adapted to binary and 12H mode, care must be taken
* to not introduce bugs.
*/
#include <linux/module.h>
#include <linux/rtc.h>
#include <linux/platform_device.h>
#include <linux/platform_data/rtc-m48t86.h>
#include <linux/bcd.h>
#include <linux/io.h>
#define M48T86_SEC 0x00
#define M48T86_SECALRM 0x01
#define M48T86_MIN 0x02
#define M48T86_MINALRM 0x03
#define M48T86_HOUR 0x04
#define M48T86_HOURALRM 0x05
#define M48T86_DOW 0x06 /* 1 = sunday */
#define M48T86_DOM 0x07
#define M48T86_MONTH 0x08 /* 1 - 12 */
#define M48T86_YEAR 0x09 /* 0 - 99 */
#define M48T86_A 0x0a
#define M48T86_B 0x0b
#define M48T86_B_SET BIT(7)
#define M48T86_B_DM BIT(2)
#define M48T86_B_H24 BIT(1)
#define M48T86_C 0x0c
#define M48T86_D 0x0d
#define M48T86_D_VRT BIT(7)
#define M48T86_NVRAM(x) (0x0e + (x))
#define M48T86_NVRAM_LEN 114
struct m48t86_rtc_info {
void __iomem *index_reg;
void __iomem *data_reg;
struct rtc_device *rtc;
struct m48t86_ops *ops;
};
static unsigned char m48t86_readb(struct device *dev, unsigned long addr)
{
struct m48t86_rtc_info *info = dev_get_drvdata(dev);
unsigned char value;
if (info->ops) {
value = info->ops->readbyte(addr);
} else {
writeb(addr, info->index_reg);
value = readb(info->data_reg);
}
return value;
}
static void m48t86_writeb(struct device *dev,
unsigned char value, unsigned long addr)
{
struct m48t86_rtc_info *info = dev_get_drvdata(dev);
if (info->ops) {
info->ops->writebyte(value, addr);
} else {
writeb(addr, info->index_reg);
writeb(value, info->data_reg);
}
}
static int m48t86_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
unsigned char reg;
reg = m48t86_readb(dev, M48T86_B);
if (reg & M48T86_B_DM) {
/* data (binary) mode */
tm->tm_sec = m48t86_readb(dev, M48T86_SEC);
tm->tm_min = m48t86_readb(dev, M48T86_MIN);
tm->tm_hour = m48t86_readb(dev, M48T86_HOUR) & 0x3f;
tm->tm_mday = m48t86_readb(dev, M48T86_DOM);
/* tm_mon is 0-11 */
tm->tm_mon = m48t86_readb(dev, M48T86_MONTH) - 1;
tm->tm_year = m48t86_readb(dev, M48T86_YEAR) + 100;
tm->tm_wday = m48t86_readb(dev, M48T86_DOW);
} else {
/* bcd mode */
tm->tm_sec = bcd2bin(m48t86_readb(dev, M48T86_SEC));
tm->tm_min = bcd2bin(m48t86_readb(dev, M48T86_MIN));
tm->tm_hour = bcd2bin(m48t86_readb(dev, M48T86_HOUR) &
0x3f);
tm->tm_mday = bcd2bin(m48t86_readb(dev, M48T86_DOM));
/* tm_mon is 0-11 */
tm->tm_mon = bcd2bin(m48t86_readb(dev, M48T86_MONTH)) - 1;
tm->tm_year = bcd2bin(m48t86_readb(dev, M48T86_YEAR)) + 100;
tm->tm_wday = bcd2bin(m48t86_readb(dev, M48T86_DOW));
}
/* correct the hour if the clock is in 12h mode */
if (!(reg & M48T86_B_H24))
if (m48t86_readb(dev, M48T86_HOUR) & 0x80)
tm->tm_hour += 12;
return rtc_valid_tm(tm);
}
static int m48t86_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
unsigned char reg;
reg = m48t86_readb(dev, M48T86_B);
/* update flag and 24h mode */
reg |= M48T86_B_SET | M48T86_B_H24;
m48t86_writeb(dev, reg, M48T86_B);
if (reg & M48T86_B_DM) {
/* data (binary) mode */
m48t86_writeb(dev, tm->tm_sec, M48T86_SEC);
m48t86_writeb(dev, tm->tm_min, M48T86_MIN);
m48t86_writeb(dev, tm->tm_hour, M48T86_HOUR);
m48t86_writeb(dev, tm->tm_mday, M48T86_DOM);
m48t86_writeb(dev, tm->tm_mon + 1, M48T86_MONTH);
m48t86_writeb(dev, tm->tm_year % 100, M48T86_YEAR);
m48t86_writeb(dev, tm->tm_wday, M48T86_DOW);
} else {
/* bcd mode */
m48t86_writeb(dev, bin2bcd(tm->tm_sec), M48T86_SEC);
m48t86_writeb(dev, bin2bcd(tm->tm_min), M48T86_MIN);
m48t86_writeb(dev, bin2bcd(tm->tm_hour), M48T86_HOUR);
m48t86_writeb(dev, bin2bcd(tm->tm_mday), M48T86_DOM);
m48t86_writeb(dev, bin2bcd(tm->tm_mon + 1), M48T86_MONTH);
m48t86_writeb(dev, bin2bcd(tm->tm_year % 100), M48T86_YEAR);
m48t86_writeb(dev, bin2bcd(tm->tm_wday), M48T86_DOW);
}
/* update ended */
reg &= ~M48T86_B_SET;
m48t86_writeb(dev, reg, M48T86_B);
return 0;
}
static int m48t86_rtc_proc(struct device *dev, struct seq_file *seq)
{
unsigned char reg;
reg = m48t86_readb(dev, M48T86_B);
seq_printf(seq, "mode\t\t: %s\n",
(reg & M48T86_B_DM) ? "binary" : "bcd");
reg = m48t86_readb(dev, M48T86_D);
seq_printf(seq, "battery\t\t: %s\n",
(reg & M48T86_D_VRT) ? "ok" : "exhausted");
return 0;
}
static const struct rtc_class_ops m48t86_rtc_ops = {
.read_time = m48t86_rtc_read_time,
.set_time = m48t86_rtc_set_time,
.proc = m48t86_rtc_proc,
};
static ssize_t m48t86_nvram_read(struct file *filp, struct kobject *kobj,
struct bin_attribute *attr,
char *buf, loff_t off, size_t count)
{
struct device *dev = kobj_to_dev(kobj);
unsigned int i;
for (i = 0; i < count; i++)
buf[i] = m48t86_readb(dev, M48T86_NVRAM(off + i));
return count;
}
static ssize_t m48t86_nvram_write(struct file *filp, struct kobject *kobj,
struct bin_attribute *attr,
char *buf, loff_t off, size_t count)
{
struct device *dev = kobj_to_dev(kobj);
unsigned int i;
for (i = 0; i < count; i++)
m48t86_writeb(dev, buf[i], M48T86_NVRAM(off + i));
return count;
}
static BIN_ATTR(nvram, 0644, m48t86_nvram_read, m48t86_nvram_write,
M48T86_NVRAM_LEN);
/*
* The RTC is an optional feature at purchase time on some Technologic Systems
* boards. Verify that it actually exists by checking if the last two bytes
* of the NVRAM can be changed.
*
* This is based on the method used in their rtc7800.c example.
*/
static bool m48t86_verify_chip(struct platform_device *pdev)
{
unsigned int offset0 = M48T86_NVRAM(M48T86_NVRAM_LEN - 2);
unsigned int offset1 = M48T86_NVRAM(M48T86_NVRAM_LEN - 1);
unsigned char tmp0, tmp1;
tmp0 = m48t86_readb(&pdev->dev, offset0);
tmp1 = m48t86_readb(&pdev->dev, offset1);
m48t86_writeb(&pdev->dev, 0x00, offset0);
m48t86_writeb(&pdev->dev, 0x55, offset1);
if (m48t86_readb(&pdev->dev, offset1) == 0x55) {
m48t86_writeb(&pdev->dev, 0xaa, offset1);
if (m48t86_readb(&pdev->dev, offset1) == 0xaa &&
m48t86_readb(&pdev->dev, offset0) == 0x00) {
m48t86_writeb(&pdev->dev, tmp0, offset0);
m48t86_writeb(&pdev->dev, tmp1, offset1);
return true;
}
}
return false;
}
static int m48t86_rtc_probe(struct platform_device *pdev)
{
struct m48t86_rtc_info *info;
unsigned char reg;
info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL);
if (!info)
return -ENOMEM;
info->ops = dev_get_platdata(&pdev->dev);
if (!info->ops) {
struct resource *res;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!res)
return -ENODEV;
info->index_reg = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(info->index_reg))
return PTR_ERR(info->index_reg);
res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
if (!res)
return -ENODEV;
info->data_reg = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(info->data_reg))
return PTR_ERR(info->data_reg);
}
dev_set_drvdata(&pdev->dev, info);
if (!m48t86_verify_chip(pdev)) {
dev_info(&pdev->dev, "RTC not present\n");
return -ENODEV;
}
info->rtc = devm_rtc_device_register(&pdev->dev, "m48t86",
&m48t86_rtc_ops, THIS_MODULE);
if (IS_ERR(info->rtc))
return PTR_ERR(info->rtc);
/* read battery status */
reg = m48t86_readb(&pdev->dev, M48T86_D);
dev_info(&pdev->dev, "battery %s\n",
(reg & M48T86_D_VRT) ? "ok" : "exhausted");
if (device_create_bin_file(&pdev->dev, &bin_attr_nvram))
dev_err(&pdev->dev, "failed to create nvram sysfs entry\n");
return 0;
}
static int m48t86_rtc_remove(struct platform_device *pdev)
{
device_remove_bin_file(&pdev->dev, &bin_attr_nvram);
return 0;
}
static struct platform_driver m48t86_rtc_platform_driver = {
.driver = {
.name = "rtc-m48t86",
},
.probe = m48t86_rtc_probe,
.remove = m48t86_rtc_remove,
};
module_platform_driver(m48t86_rtc_platform_driver);
MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
MODULE_DESCRIPTION("M48T86 RTC driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:rtc-m48t86");
Reference in New Issue View Git Blame Copy Permalink