解决RTC内核驱动的问题bm8563

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 = &reg,
		},
		{
			.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:

cpp 复制代码
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";
};
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