常用pcf-8563 , 国产平替BM8563(驱动管脚一致)；
实时时钟是很常用的一个外设，通过实时时钟我们就可以知道年、月、日和时间等信息。
因此在需要记录时间的场合就需要实时时钟，可以使用专用的实时时钟芯片来完成此功能
RTC 设备驱动是一个标准的字符设备驱动，应用程序通过
open
、
release
、
read
、
write
和
ioctl 等函数完成对 RTC
设备的操作
测试平台：君正x2600；
makefile文件：
# 开发板Linux内核的实际路径
# KDIR变量
KDIR:=/mnt/new_disk/x2600_linux/src/kernel/kernel/
# 获取当前目录
PWD:=$(shell pwd)
# obj-m表示将 chrdevbase.c这个文件 编译为 chrdevbase.ko模块。
obj-m += rtc-bm8563.o
# 编译成模块
all:
make -C $(KDIR) M=$(PWD) modules
clean:
make -C $(KDIR) M=$(PWD) clean
驱动编译代码：
// SPDX-License-Identifier: GPL-2.0-only
/*
* An I2C driver for the Philips BM8563 RTC
* Copyright 2005-06 Tower Technologies
*
* Author: Alessandro Zummo <a.zummo@towertech.it>
* Maintainers: http://www.nslu2-linux.org/
*
* based on the other drivers in this same directory.
*
* http://www.semiconductors.philips.com/acrobat/datasheets/BM8563-04.pdf
*/
#include <linux/clk-provider.h>
#include <linux/i2c.h>
#include <linux/bcd.h>
#include <linux/rtc.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/err.h>
#include <linux/of_gpio.h>
#define BM8563_REG_ST1 0x00 /* status */
#define BM8563_REG_ST2 0x01
#define BM8563_BIT_AIE BIT(1)
#define BM8563_BIT_AF BIT(3)
#define BM8563_BITS_ST2_N (7 << 5)
#define BM8563_REG_SC 0x02 /* datetime */
#define BM8563_REG_MN 0x03
#define BM8563_REG_HR 0x04
#define BM8563_REG_DM 0x05
#define BM8563_REG_DW 0x06
#define BM8563_REG_MO 0x07
#define BM8563_REG_YR 0x08
#define BM8563_REG_AMN 0x09 /* alarm */
#define BM8563_REG_CLKO 0x0D /* clock out */
#define BM8563_REG_CLKO_FE 0x80 /* clock out enabled */
#define BM8563_REG_CLKO_F_MASK 0x03 /* frequenc mask */
#define BM8563_REG_CLKO_F_32768HZ 0x00
#define BM8563_REG_CLKO_F_1024HZ 0x01
#define BM8563_REG_CLKO_F_32HZ 0x02
#define BM8563_REG_CLKO_F_1HZ 0x03
#define BM8563_REG_TMRC 0x0E /* timer control */
#define BM8563_TMRC_ENABLE BIT(7)
#define BM8563_TMRC_4096 0
#define BM8563_TMRC_64 1
#define BM8563_TMRC_1 2
#define BM8563_TMRC_1_60 3
#define BM8563_TMRC_MASK 3
#define BM8563_REG_TMR 0x0F /* timer */
#define BM8563_SC_LV 0x80 /* low voltage */
#define BM8563_MO_C 0x80 /* century */
static struct i2c_driver bm8563_driver;
struct bm8563 {
struct rtc_device *rtc;
/*
* The meaning of MO_C bit varies by the chip type.
* From BM8563 datasheet: this bit is toggled when the years
* register overflows from 99 to 00
* 0 indicates the century is 20xx
* 1 indicates the century is 19xx
* From RTC8564 datasheet: this bit indicates change of
* century. When the year digit data overflows from 99 to 00,
* this bit is set. By presetting it to 0 while still in the
* 20th century, it will be set in year 2000, ...
* There seems no reliable way to know how the system use this
* bit. So let's do it heuristically, assuming we are live in
* 1970...2069.
*/
int c_polarity; /* 0: MO_C=1 means 19xx, otherwise MO_C=1 means 20xx */
struct i2c_client *client;
#ifdef CONFIG_COMMON_CLK
struct clk_hw clkout_hw;
#endif
};
static int bm8563_read_block_data(struct i2c_client *client, unsigned char reg,
unsigned char length, unsigned char *buf)
{
struct i2c_msg msgs[] = {
{/* setup read ptr */
.addr = client->addr,
.len = 1,
.buf = ®,
},
{
.addr = client->addr,
.flags = I2C_M_RD,
.len = length,
.buf = buf
},
};
if ((i2c_transfer(client->adapter, msgs, 2)) != 2) {
dev_err(&client->dev, "%s: read error\n", __func__);
return -EIO;
}
return 0;
}
static int bm8563_write_block_data(struct i2c_client *client,
unsigned char reg, unsigned char length,
unsigned char *buf)
{
int i, err;
for (i = 0; i < length; i++) {
unsigned char data[2] = { reg + i, buf[i] };
err = i2c_master_send(client, data, sizeof(data));
if (err != sizeof(data)) {
dev_err(&client->dev,
"%s: err=%d addr=%02x, data=%02x\n",
__func__, err, data[0], data[1]);
return -EIO;
}
}
return 0;
}
static int bm8563_set_alarm_mode(struct i2c_client *client, bool on)
{
unsigned char buf;
int err;
err = bm8563_read_block_data(client, BM8563_REG_ST2, 1, &buf);
if (err < 0)
return err;
if (on)
buf |= BM8563_BIT_AIE;
else
buf &= ~BM8563_BIT_AIE;
buf &= ~(BM8563_BIT_AF | BM8563_BITS_ST2_N);
err = bm8563_write_block_data(client, BM8563_REG_ST2, 1, &buf);
if (err < 0) {
dev_err(&client->dev, "%s: write error\n", __func__);
return -EIO;
}
return 0;
}
static int bm8563_get_alarm_mode(struct i2c_client *client, unsigned char *en,
unsigned char *pen)
{
unsigned char buf;
int err;
err = bm8563_read_block_data(client, BM8563_REG_ST2, 1, &buf);
if (err)
return err;
if (en)
*en = !!(buf & BM8563_BIT_AIE);
if (pen)
*pen = !!(buf & BM8563_BIT_AF);
return 0;
}
static irqreturn_t bm8563_irq(int irq, void *dev_id)
{
struct bm8563 *bm8563 = i2c_get_clientdata(dev_id);
int err;
char pending;
err = bm8563_get_alarm_mode(bm8563->client, NULL, &pending);
if (err)
return IRQ_NONE;
if (pending) {
rtc_update_irq(bm8563->rtc, 1, RTC_IRQF | RTC_AF);
bm8563_set_alarm_mode(bm8563->client, 1);
return IRQ_HANDLED;
}
return IRQ_NONE;
}
/*
* In the routines that deal directly with the bm8563 hardware, we use
* rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
*/
static int bm8563_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
struct i2c_client *client = to_i2c_client(dev);
struct bm8563 *bm8563 = i2c_get_clientdata(client);
unsigned char buf[9];
int err;
err = bm8563_read_block_data(client, BM8563_REG_ST1, 9, buf);
if (err)
return err;
if (buf[BM8563_REG_SC] & BM8563_SC_LV) {
dev_err(&client->dev,
"low voltage detected, date/time is not reliable.\n");
return -EINVAL;
}
dev_dbg(&client->dev,
"%s: raw data is st1=%02x, st2=%02x, sec=%02x, min=%02x, hr=%02x, "
"mday=%02x, wday=%02x, mon=%02x, year=%02x\n",
__func__,
buf[0], buf[1], buf[2], buf[3],
buf[4], buf[5], buf[6], buf[7],
buf[8]);
tm->tm_sec = bcd2bin(buf[BM8563_REG_SC] & 0x7F);
tm->tm_min = bcd2bin(buf[BM8563_REG_MN] & 0x7F);
tm->tm_hour = bcd2bin(buf[BM8563_REG_HR] & 0x3F); /* rtc hr 0-23 */
tm->tm_mday = bcd2bin(buf[BM8563_REG_DM] & 0x3F);
tm->tm_wday = buf[BM8563_REG_DW] & 0x07;
tm->tm_mon = bcd2bin(buf[BM8563_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
tm->tm_year = bcd2bin(buf[BM8563_REG_YR]) + 100;
/* detect the polarity heuristically. see note above. */
bm8563->c_polarity = (buf[BM8563_REG_MO] & BM8563_MO_C) ?
(tm->tm_year >= 100) : (tm->tm_year < 100);
dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
"mday=%d, mon=%d, year=%d, wday=%d\n",
__func__,
tm->tm_sec, tm->tm_min, tm->tm_hour,
tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
return 0;
}
static int bm8563_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
struct i2c_client *client = to_i2c_client(dev);
struct bm8563 *bm8563 = i2c_get_clientdata(client);
unsigned char buf[9];
dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
"mday=%d, mon=%d, year=%d, wday=%d\n",
__func__,
tm->tm_sec, tm->tm_min, tm->tm_hour,
tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
/* hours, minutes and seconds */
buf[BM8563_REG_SC] = bin2bcd(tm->tm_sec);
buf[BM8563_REG_MN] = bin2bcd(tm->tm_min);
buf[BM8563_REG_HR] = bin2bcd(tm->tm_hour);
buf[BM8563_REG_DM] = bin2bcd(tm->tm_mday);
/* month, 1 - 12 */
buf[BM8563_REG_MO] = bin2bcd(tm->tm_mon + 1);
/* year and century */
buf[BM8563_REG_YR] = bin2bcd(tm->tm_year - 100);
if (bm8563->c_polarity ? (tm->tm_year >= 100) : (tm->tm_year < 100))
buf[BM8563_REG_MO] |= BM8563_MO_C;
buf[BM8563_REG_DW] = tm->tm_wday & 0x07;
return bm8563_write_block_data(client, BM8563_REG_SC,
9 - BM8563_REG_SC, buf + BM8563_REG_SC);
}
static int bm8563_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
{
struct i2c_client *client = to_i2c_client(dev);
int ret;
switch (cmd) {
case RTC_VL_READ:
ret = i2c_smbus_read_byte_data(client, BM8563_REG_SC);
if (ret < 0)
return ret;
return put_user(ret & BM8563_SC_LV ? RTC_VL_DATA_INVALID : 0,
(unsigned int __user *)arg);
default:
return -ENOIOCTLCMD;
}
}
static int bm8563_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *tm)
{
struct i2c_client *client = to_i2c_client(dev);
unsigned char buf[4];
int err;
err = bm8563_read_block_data(client, BM8563_REG_AMN, 4, buf);
if (err)
return err;
dev_dbg(&client->dev,
"%s: raw data is min=%02x, hr=%02x, mday=%02x, wday=%02x\n",
__func__, buf[0], buf[1], buf[2], buf[3]);
tm->time.tm_sec = 0;
tm->time.tm_min = bcd2bin(buf[0] & 0x7F);
tm->time.tm_hour = bcd2bin(buf[1] & 0x3F);
tm->time.tm_mday = bcd2bin(buf[2] & 0x3F);
tm->time.tm_wday = bcd2bin(buf[3] & 0x7);
err = bm8563_get_alarm_mode(client, &tm->enabled, &tm->pending);
if (err < 0)
return err;
dev_dbg(&client->dev, "%s: tm is mins=%d, hours=%d, mday=%d, wday=%d,"
" enabled=%d, pending=%d\n", __func__, tm->time.tm_min,
tm->time.tm_hour, tm->time.tm_mday, tm->time.tm_wday,
tm->enabled, tm->pending);
return 0;
}
static int bm8563_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *tm)
{
struct i2c_client *client = to_i2c_client(dev);
unsigned char buf[4];
int err;
/* The alarm has no seconds, round up to nearest minute */
if (tm->time.tm_sec) {
time64_t alarm_time = rtc_tm_to_time64(&tm->time);
alarm_time += 60 - tm->time.tm_sec;
rtc_time64_to_tm(alarm_time, &tm->time);
}
dev_dbg(dev, "%s, min=%d hour=%d wday=%d mday=%d "
"enabled=%d pending=%d\n", __func__,
tm->time.tm_min, tm->time.tm_hour, tm->time.tm_wday,
tm->time.tm_mday, tm->enabled, tm->pending);
buf[0] = bin2bcd(tm->time.tm_min);
buf[1] = bin2bcd(tm->time.tm_hour);
buf[2] = bin2bcd(tm->time.tm_mday);
buf[3] = tm->time.tm_wday & 0x07;
err = bm8563_write_block_data(client, BM8563_REG_AMN, 4, buf);
if (err)
return err;
return bm8563_set_alarm_mode(client, !!tm->enabled);
}
static int bm8563_irq_enable(struct device *dev, unsigned int enabled)
{
dev_dbg(dev, "%s: en=%d\n", __func__, enabled);
return bm8563_set_alarm_mode(to_i2c_client(dev), !!enabled);
}
#ifdef CONFIG_COMMON_CLK
/*
* Handling of the clkout
*/
#define clkout_hw_to_bm8563(_hw) container_of(_hw, struct bm8563, clkout_hw)
static const int clkout_rates[] = {
32768,
1024,
32,
1,
};
static unsigned long bm8563_clkout_recalc_rate(struct clk_hw *hw,
unsigned long parent_rate)
{
struct bm8563 *bm8563 = clkout_hw_to_bm8563(hw);
struct i2c_client *client = bm8563->client;
unsigned char buf;
int ret = bm8563_read_block_data(client, BM8563_REG_CLKO, 1, &buf);
if (ret < 0)
return 0;
buf &= BM8563_REG_CLKO_F_MASK;
return clkout_rates[buf];
}
static long bm8563_clkout_round_rate(struct clk_hw *hw, unsigned long rate,
unsigned long *prate)
{
int i;
for (i = 0; i < ARRAY_SIZE(clkout_rates); i++)
if (clkout_rates[i] <= rate)
return clkout_rates[i];
return 0;
}
static int bm8563_clkout_set_rate(struct clk_hw *hw, unsigned long rate,
unsigned long parent_rate)
{
struct bm8563 *bm8563 = clkout_hw_to_bm8563(hw);
struct i2c_client *client = bm8563->client;
unsigned char buf;
int ret = bm8563_read_block_data(client, BM8563_REG_CLKO, 1, &buf);
int i;
if (ret < 0)
return ret;
for (i = 0; i < ARRAY_SIZE(clkout_rates); i++)
if (clkout_rates[i] == rate) {
buf &= ~BM8563_REG_CLKO_F_MASK;
buf |= i;
ret = bm8563_write_block_data(client,
BM8563_REG_CLKO, 1,
&buf);
return ret;
}
return -EINVAL;
}
static int bm8563_clkout_control(struct clk_hw *hw, bool enable)
{
struct bm8563 *bm8563 = clkout_hw_to_bm8563(hw);
struct i2c_client *client = bm8563->client;
unsigned char buf;
int ret = bm8563_read_block_data(client, BM8563_REG_CLKO, 1, &buf);
if (ret < 0)
return ret;
if (enable)
buf |= BM8563_REG_CLKO_FE;
else
buf &= ~BM8563_REG_CLKO_FE;
ret = bm8563_write_block_data(client, BM8563_REG_CLKO, 1, &buf);
return ret;
}
static int bm8563_clkout_prepare(struct clk_hw *hw)
{
return bm8563_clkout_control(hw, 1);
}
static void bm8563_clkout_unprepare(struct clk_hw *hw)
{
bm8563_clkout_control(hw, 0);
}
static int bm8563_clkout_is_prepared(struct clk_hw *hw)
{
struct bm8563 *bm8563 = clkout_hw_to_bm8563(hw);
struct i2c_client *client = bm8563->client;
unsigned char buf;
int ret = bm8563_read_block_data(client, BM8563_REG_CLKO, 1, &buf);
if (ret < 0)
return ret;
return !!(buf & BM8563_REG_CLKO_FE);
}
static const struct clk_ops bm8563_clkout_ops = {
.prepare = bm8563_clkout_prepare,
.unprepare = bm8563_clkout_unprepare,
.is_prepared = bm8563_clkout_is_prepared,
.recalc_rate = bm8563_clkout_recalc_rate,
.round_rate = bm8563_clkout_round_rate,
.set_rate = bm8563_clkout_set_rate,
};
static struct clk *bm8563_clkout_register_clk(struct bm8563 *bm8563)
{
struct i2c_client *client = bm8563->client;
struct device_node *node = client->dev.of_node;
struct clk *clk;
struct clk_init_data init;
int ret;
unsigned char buf;
/* disable the clkout output */
buf = 0;
ret = bm8563_write_block_data(client, BM8563_REG_CLKO, 1, &buf);
if (ret < 0)
return ERR_PTR(ret);
init.name = "bm8563-clkout";
init.ops = &bm8563_clkout_ops;
init.flags = 0;
init.parent_names = NULL;
init.num_parents = 0;
bm8563->clkout_hw.init = &init;
/* optional override of the clockname */
of_property_read_string(node, "clock-output-names", &init.name);
/* register the clock */
clk = devm_clk_register(&client->dev, &bm8563->clkout_hw);
if (!IS_ERR(clk))
of_clk_add_provider(node, of_clk_src_simple_get, clk);
return clk;
}
#endif
static const struct rtc_class_ops bm8563_rtc_ops = {
.ioctl = bm8563_rtc_ioctl,
.read_time = bm8563_rtc_read_time,
.set_time = bm8563_rtc_set_time,
.read_alarm = bm8563_rtc_read_alarm,
.set_alarm = bm8563_rtc_set_alarm,
.alarm_irq_enable = bm8563_irq_enable,
};
static int bm8563_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct bm8563 *bm8563;
int err, value;
unsigned char buf;
unsigned int vdd_en_gpio;
enum of_gpio_flags flags;
vdd_en_gpio = of_get_named_gpio_flags(client->dev.of_node, "ingenic,vdd-en-gpio", 0, &flags);
if(gpio_is_valid(vdd_en_gpio)) {
if(devm_gpio_request(&client->dev, vdd_en_gpio, "rtc-vdd-en") < 0) {
printk("Failed to request rtc-vdd-en-gpio pin!\n");
}
value = (flags & OF_GPIO_ACTIVE_LOW) ? 0 : 1;
gpio_direction_output(vdd_en_gpio, value);
printk("Set rtc enable gpio %u, value %d\n", vdd_en_gpio, value);
} else {
dev_warn(&client->dev, "invalid gpio rtc-vdd-en-gpio: %d\n", vdd_en_gpio);
}
if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
return -ENODEV;
bm8563 = devm_kzalloc(&client->dev, sizeof(struct bm8563),
GFP_KERNEL);
if (!bm8563)
return -ENOMEM;
i2c_set_clientdata(client, bm8563);
bm8563->client = client;
device_set_wakeup_capable(&client->dev, 1);
/* Set timer to lowest frequency to save power (ref Haoyu datasheet) */
buf = BM8563_TMRC_1_60;
err = bm8563_write_block_data(client, BM8563_REG_TMRC, 1, &buf);
if (err < 0) {
dev_err(&client->dev, "%s: write error\n", __func__);
return err;
}
/* Clear flags and disable interrupts */
buf = 0;
err = bm8563_write_block_data(client, BM8563_REG_ST2, 1, &buf);
if (err < 0) {
dev_err(&client->dev, "%s: write error\n", __func__);
return err;
}
bm8563->rtc = devm_rtc_allocate_device(&client->dev);
if (IS_ERR(bm8563->rtc))
return PTR_ERR(bm8563->rtc);
bm8563->rtc->ops = &bm8563_rtc_ops;
/* the bm8563 alarm only supports a minute accuracy */
bm8563->rtc->uie_unsupported = 1;
bm8563->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
bm8563->rtc->range_max = RTC_TIMESTAMP_END_2099;
bm8563->rtc->set_start_time = true;
if (client->irq > 0) {
err = devm_request_threaded_irq(&client->dev, client->irq,
NULL, bm8563_irq,
IRQF_SHARED | IRQF_ONESHOT | IRQF_TRIGGER_LOW,
bm8563_driver.driver.name, client);
if (err) {
dev_err(&client->dev, "unable to request IRQ %d\n",
client->irq);
return err;
}
}
err = rtc_register_device(bm8563->rtc);
if (err)
return err;
#ifdef CONFIG_COMMON_CLK
/* register clk in common clk framework */
bm8563_clkout_register_clk(bm8563);
#endif
return 0;
}
static const struct i2c_device_id bm8563_id[] = {
{ "bm8563", 0 },
{ }
};
static const struct of_device_id bm8563_of_match[] = {
{ .compatible = "belling,bm8563" },
{}
};
static struct i2c_driver bm8563_driver = {
.driver = {
.name = "rtc_bm8563",
.of_match_table = of_match_ptr(bm8563_of_match),
},
.probe = bm8563_probe,
.id_table = bm8563_id,
};
module_i2c_driver(bm8563_driver);
MODULE_AUTHOR("<xxl@163.com>");
MODULE_DESCRIPTION("belling BM8563 RTC8564 RTC driver");
MODULE_LICENSE("GPL");
make之后，生产了ko文件；
测试结果：
问题和解决：
1.i2c和pcf8563的内核启动失败
根据问题，我在make menucofig上取消i2c的驱动
开启君正RTC的驱动
然后将编译好的内核烧录进去，程序启动：
不再看到pcf8563的报错信息，但是我调用hwclock的指令时，会报错
can't open '/dev/misc/rtc': No such file or directory
这个表示--rtc驱动没有加载成功！
我去查了网上一下资料：
比如hwclock: can't open '/dev/misc/rtc': No such file or directory_读行四海_新浪博客
我确定，我已经加载了君正官方的RTC支持，并且启动的iic的配置；
2.hwclock报错：
做了横向对比，查出如下问题：设备树没有做对应的设置
加入代码：
rtc: rtc@0x10003000 {
compatible = "ingenic,rtc";
reg = <0x10003000 0x4c>;
interrupt-parent = <&core_intc>;
interrupts = <IRQ_RTC>;
system-power-controller;
power-on-press-ms = <1000>;
status = "ok";
};
