常用pcf-8563 , 国产平替BM8563(驱动管脚一致)；

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) modulesclean: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_CLKstruct 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;elsebuf &= ~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;elsebuf &= ~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;
}
#endifstatic 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);
#endifreturn 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";
};