Platform: Rockchip
OS: Android 6.0
Kernel: 3.10.92

• • • 设备部分
    • 驱动部分
    • 改动部分
    • 参考

在网上的其他branch上找到一份RX8010SJ的驱动，但是有点问题，先贴代码，再说明修改部分。
设备部分：
比较简单，确定I2C端口以及设备地址就行。
&i2c1 {
status = “okay”;
rx8010: rx8010@32 {
compatible = “epson,rx8010”;
reg = <0x32>;
status = “okay”;
};
};
驱动部分：
此驱动已经可以读写时间，alarm部分因为没有需求，所以硬件没接，也未做测试。

/* * Driver for the Epson RTC module RX-8010 SJ * * Copyright(C) Timesys Corporation 2015 * Copyright(C) General Electric Company 2015 * * 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. * */#include #include #include #include #include #include #define RX8010_SEC0x10 #define RX8010_MIN0x11 #define RX8010_HOUR0x12 #define RX8010_WDAY0x13 #define RX8010_MDAY0x14 #define RX8010_MONTH0x15 #define RX8010_YEAR0x16 #define RX8010_YEAR0x16 #define RX8010_RESV170x17 #define RX8010_ALMIN0x18 #define RX8010_ALHOUR0x19 #define RX8010_ALWDAY0x1A #define RX8010_TCOUNT0 0x1B #define RX8010_TCOUNT1 0x1C #define RX8010_EXT0x1D #define RX8010_FLAG0x1E #define RX8010_CTRL0x1F /* 0x20 to 0x2F are user registers */ #define RX8010_RESV300x30 #define RX8010_RESV310x31 #define RX8010_IRQ0x32#define RX8010_EXT_WADABIT(3)#define RX8010_FLAG_VLFBIT(1) #define RX8010_FLAG_AFBIT(3) #define RX8010_FLAG_TFBIT(4) #define RX8010_FLAG_UFBIT(5)#define RX8010_CTRL_AIEBIT(3) #define RX8010_CTRL_UIEBIT(5) #define RX8010_CTRL_STOP BIT(6) #define RX8010_CTRL_TEST BIT(7)#define RX8010_ALARM_AEBIT(7)static const struct i2c_device_id rx8010_id[] = { { "rx8010", 0 }, { } }; MODULE_DEVICE_TABLE(i2c, rx8010_id); static const struct of_device_id rx8010_of_match[] = { { .compatible = "epson,rx8010" }, { } }; MODULE_DEVICE_TABLE(of, rx8010_of_match); struct rx8010_data { struct i2c_client *client; struct rtc_device *rtc; u8 ctrlreg; }; static irqreturn_t rx8010_irq_1_handler(int irq, void *dev_id) { struct i2c_client *client = dev_id; struct rx8010_data *rx8010 = i2c_get_clientdata(client); int flagreg; mutex_lock(&rx8010->rtc->ops_lock); flagreg = i2c_smbus_read_byte_data(client, RX8010_FLAG); if (flagreg <= 0) { mutex_unlock(&rx8010->rtc->ops_lock); return IRQ_NONE; }if (flagreg & RX8010_FLAG_VLF) dev_warn(&client->dev, "Frequency stop detected\n"); if (flagreg & RX8010_FLAG_TF) { flagreg &= ~RX8010_FLAG_TF; rtc_update_irq(rx8010->rtc, 1, RTC_PF | RTC_IRQF); }if (flagreg & RX8010_FLAG_AF) { flagreg &= ~RX8010_FLAG_AF; rtc_update_irq(rx8010->rtc, 1, RTC_AF | RTC_IRQF); }if (flagreg & RX8010_FLAG_UF) { flagreg &= ~RX8010_FLAG_UF; rtc_update_irq(rx8010->rtc, 1, RTC_UF | RTC_IRQF); }i2c_smbus_write_byte_data(client, RX8010_FLAG, flagreg); mutex_unlock(&rx8010->rtc->ops_lock); return IRQ_HANDLED; }static int rx8010_get_time(struct device *dev, struct rtc_time *dt) { struct rx8010_data *rx8010 = dev_get_drvdata(dev); u8 date[7]; int flagreg; int err; flagreg = i2c_smbus_read_byte_data(rx8010->client, RX8010_FLAG); if (flagreg < 0) return flagreg; if (flagreg & RX8010_FLAG_VLF) { dev_warn(dev, "Frequency stop detected\n"); return -EINVAL; }err = i2c_smbus_read_i2c_block_data(rx8010->client, RX8010_SEC, 7, date); if (err != 7) return err < 0 ? err : -EIO; dt->tm_sec = bcd2bin(date[RX8010_SEC - RX8010_SEC] & 0x7f); dt->tm_min = bcd2bin(date[RX8010_MIN - RX8010_SEC] & 0x7f); dt->tm_hour = bcd2bin(date[RX8010_HOUR - RX8010_SEC] & 0x3f); dt->tm_mday = bcd2bin(date[RX8010_MDAY - RX8010_SEC] & 0x3f); dt->tm_mon = bcd2bin(date[RX8010_MONTH - RX8010_SEC] & 0x1f) - 1; dt->tm_year = bcd2bin(date[RX8010_YEAR - RX8010_SEC]) + 100; dt->tm_wday = ffs(date[RX8010_WDAY - RX8010_SEC] & 0x7f); return rtc_valid_tm(dt); }static int rx8010_set_time(struct device *dev, struct rtc_time *dt) { struct rx8010_data *rx8010 = dev_get_drvdata(dev); u8 date[7]; int ctrl, flagreg; int ret; if ((dt->tm_year < 100) || (dt->tm_year > 199)) return -EINVAL; /* set STOP bit before changing clock/calendar */ ctrl = i2c_smbus_read_byte_data(rx8010->client, RX8010_CTRL); if (ctrl < 0) return ctrl; rx8010->ctrlreg = ctrl | RX8010_CTRL_STOP; ret = i2c_smbus_write_byte_data(rx8010->client, RX8010_CTRL, rx8010->ctrlreg); if (ret < 0) return ret; date[RX8010_SEC - RX8010_SEC] = bin2bcd(dt->tm_sec); date[RX8010_MIN - RX8010_SEC] = bin2bcd(dt->tm_min); date[RX8010_HOUR - RX8010_SEC] = bin2bcd(dt->tm_hour); date[RX8010_MDAY - RX8010_SEC] = bin2bcd(dt->tm_mday); date[RX8010_MONTH - RX8010_SEC] = bin2bcd(dt->tm_mon + 1); date[RX8010_YEAR - RX8010_SEC] = bin2bcd(dt->tm_year - 100); date[RX8010_WDAY - RX8010_SEC] = bin2bcd(1 << dt->tm_wday); ret = i2c_smbus_write_i2c_block_data(rx8010->client, RX8010_SEC, 7, date); if (ret < 0) return ret; /* clear STOP bit after changing clock/calendar */ ctrl = i2c_smbus_read_byte_data(rx8010->client, RX8010_CTRL); if (ctrl < 0) return ctrl; rx8010->ctrlreg = ctrl & ~RX8010_CTRL_STOP; ret = i2c_smbus_write_byte_data(rx8010->client, RX8010_CTRL, rx8010->ctrlreg); if (ret < 0) return ret; flagreg = i2c_smbus_read_byte_data(rx8010->client, RX8010_FLAG); if (flagreg < 0) { return flagreg; }if (flagreg & RX8010_FLAG_VLF) ret = i2c_smbus_write_byte_data(rx8010->client, RX8010_FLAG, flagreg & ~RX8010_FLAG_VLF); return 0; }static int rx8010_init_client(struct i2c_client *client) { struct rx8010_data *rx8010 = i2c_get_clientdata(client); u8 ctrl[2]; int need_clear = 0, err = 0; u8 flag; flag = i2c_smbus_read_byte_data(client, RX8010_FLAG); if (err < 0) return err; flag &= ~(RX8010_FLAG_VLF); err = i2c_smbus_write_byte_data(client, RX8010_FLAG, flag); /* Initialize reserved registers as specified in datasheet */ err = i2c_smbus_write_byte_data(client, RX8010_RESV17, 0xD8); if (err < 0) return err; err = i2c_smbus_write_byte_data(client, RX8010_RESV30, 0x00); if (err < 0) return err; err = i2c_smbus_write_byte_data(client, RX8010_RESV31, 0x08); if (err < 0) return err; err = i2c_smbus_write_byte_data(client, RX8010_IRQ, 0x00); if (err < 0) return err; err = i2c_smbus_read_i2c_block_data(rx8010->client, RX8010_FLAG, 2, ctrl); if (err != 2) return err < 0 ? err : -EIO; if (ctrl[0] & RX8010_FLAG_VLF) dev_warn(&client->dev, "Frequency stop was detected\n"); if (ctrl[0] & RX8010_FLAG_AF) { dev_warn(&client->dev, "Alarm was detected\n"); need_clear = 1; }if (ctrl[0] & RX8010_FLAG_TF) need_clear = 1; if (ctrl[0] & RX8010_FLAG_UF) need_clear = 1; if (need_clear) { ctrl[0] &= ~(RX8010_FLAG_AF | RX8010_FLAG_TF | RX8010_FLAG_UF); err = i2c_smbus_write_byte_data(client, RX8010_FLAG, ctrl[0]); if (err < 0) return err; }rx8010->ctrlreg = (ctrl[1] & ~RX8010_CTRL_TEST); return err; }static int rx8010_read_alarm(struct device *dev, struct rtc_wkalrm *t) { struct rx8010_data *rx8010 = dev_get_drvdata(dev); struct i2c_client *client = rx8010->client; u8 alarmvals[3]; int flagreg; int err; err = i2c_smbus_read_i2c_block_data(client, RX8010_ALMIN, 3, alarmvals); if (err != 3) return err < 0 ? err : -EIO; flagreg = i2c_smbus_read_byte_data(client, RX8010_FLAG); if (flagreg < 0) return flagreg; t->time.tm_sec = 0; t->time.tm_min = bcd2bin(alarmvals[0] & 0x7f); t->time.tm_hour = bcd2bin(alarmvals[1] & 0x3f); if (!(alarmvals[2] & RX8010_ALARM_AE)) t->time.tm_mday = bcd2bin(alarmvals[2] & 0x7f); t->enabled = !!(rx8010->ctrlreg & RX8010_CTRL_AIE); t->pending = (flagreg & RX8010_FLAG_AF) && t->enabled; return err; }static int rx8010_set_alarm(struct device *dev, struct rtc_wkalrm *t) { struct i2c_client *client = to_i2c_client(dev); struct rx8010_data *rx8010 = dev_get_drvdata(dev); u8 alarmvals[3]; int extreg, flagreg; int err; flagreg = i2c_smbus_read_byte_data(client, RX8010_FLAG); if (flagreg < 0) { return flagreg; }if (rx8010->ctrlreg & (RX8010_CTRL_AIE | RX8010_CTRL_UIE)) { rx8010->ctrlreg &= ~(RX8010_CTRL_AIE | RX8010_CTRL_UIE); err = i2c_smbus_write_byte_data(rx8010->client, RX8010_CTRL, rx8010->ctrlreg); if (err < 0) { return err; } }flagreg &= ~RX8010_FLAG_AF; err = i2c_smbus_write_byte_data(rx8010->client, RX8010_FLAG, flagreg); if (err < 0) return err; alarmvals[0] = bin2bcd(t->time.tm_min); alarmvals[1] = bin2bcd(t->time.tm_hour); alarmvals[2] = bin2bcd(t->time.tm_mday); err = i2c_smbus_write_i2c_block_data(rx8010->client, RX8010_ALMIN, 2, alarmvals); if (err < 0) return err; extreg = i2c_smbus_read_byte_data(client, RX8010_EXT); if (extreg < 0) return extreg; extreg |= RX8010_EXT_WADA; err = i2c_smbus_write_byte_data(rx8010->client, RX8010_EXT, extreg); if (err < 0) return err; if (alarmvals[2] == 0) alarmvals[2] |= RX8010_ALARM_AE; err = i2c_smbus_write_byte_data(rx8010->client, RX8010_ALWDAY, alarmvals[2]); if (err < 0) return err; if (t->enabled) { if (rx8010->rtc->uie_rtctimer.enabled) rx8010->ctrlreg |= RX8010_CTRL_UIE; if (rx8010->rtc->aie_timer.enabled) rx8010->ctrlreg |= (RX8010_CTRL_AIE | RX8010_CTRL_UIE); err = i2c_smbus_write_byte_data(rx8010->client, RX8010_CTRL, rx8010->ctrlreg); if (err < 0) return err; }return 0; }static int rx8010_alarm_irq_enable(struct device *dev, unsigned int enabled) { struct i2c_client *client = to_i2c_client(dev); struct rx8010_data *rx8010 = dev_get_drvdata(dev); int flagreg; u8 ctrl; int err; ctrl = rx8010->ctrlreg; if (enabled) { if (rx8010->rtc->uie_rtctimer.enabled) ctrl |= RX8010_CTRL_UIE; if (rx8010->rtc->aie_timer.enabled) ctrl |= (RX8010_CTRL_AIE | RX8010_CTRL_UIE); } else { if (!rx8010->rtc->uie_rtctimer.enabled) ctrl &= ~RX8010_CTRL_UIE; if (!rx8010->rtc->aie_timer.enabled) ctrl &= ~RX8010_CTRL_AIE; }flagreg = i2c_smbus_read_byte_data(client, RX8010_FLAG); if (flagreg < 0) return flagreg; flagreg &= ~RX8010_FLAG_AF; err = i2c_smbus_write_byte_data(rx8010->client, RX8010_FLAG, flagreg); if (err < 0) return err; if (ctrl != rx8010->ctrlreg) { rx8010->ctrlreg = ctrl; err = i2c_smbus_write_byte_data(rx8010->client, RX8010_CTRL, rx8010->ctrlreg); if (err < 0) return err; }return 0; }static int rx8010_ioctl(struct device *dev, unsigned int cmd, unsigned long arg) { struct i2c_client *client = to_i2c_client(dev); struct rx8010_data *rx8010 = dev_get_drvdata(dev); int ret, tmp; int flagreg; switch (cmd) { case RTC_VL_READ: flagreg = i2c_smbus_read_byte_data(rx8010->client, RX8010_FLAG); if (flagreg < 0) return flagreg; tmp = !!(flagreg & RX8010_FLAG_VLF); if (copy_to_user((void __user *)arg, &tmp, sizeof(int))) return -EFAULT; return 0; case RTC_VL_CLR: flagreg = i2c_smbus_read_byte_data(rx8010->client, RX8010_FLAG); if (flagreg < 0) { return flagreg; }flagreg &= ~RX8010_FLAG_VLF; ret = i2c_smbus_write_byte_data(client, RX8010_FLAG, flagreg); if (ret < 0) return ret; return 0; default: return -ENOIOCTLCMD; } }static struct rtc_class_ops rx8010_rtc_ops = { .read_time = rx8010_get_time, .set_time = rx8010_set_time, .ioctl = rx8010_ioctl, }; static int rx8010_probe(struct i2c_client *client, const struct i2c_device_id *id) { struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent); struct rx8010_data *rx8010; int err = 0; if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_I2C_BLOCK)) { dev_err(&adapter->dev, "doesn't support required functionality\n"); return -EIO; }rx8010 = devm_kzalloc(&client->dev, sizeof(struct rx8010_data), GFP_KERNEL); if (!rx8010) return -ENOMEM; rx8010->client = client; i2c_set_clientdata(client, rx8010); err = rx8010_init_client(client); if (err) return err; if (client->irq > 0) { dev_info(&client->dev, "IRQ %d supplied\n", client->irq); err = devm_request_threaded_irq(&client->dev, client->irq, NULL, rx8010_irq_1_handler, IRQF_TRIGGER_LOW | IRQF_ONESHOT, "rx8010", client); if (err) { dev_err(&client->dev, "unable to request IRQ\n"); client->irq = 0; } else { rx8010_rtc_ops.read_alarm = rx8010_read_alarm; rx8010_rtc_ops.set_alarm = rx8010_set_alarm; rx8010_rtc_ops.alarm_irq_enable = rx8010_alarm_irq_enable; } }rx8010_rtc_ops.read_alarm = rx8010_read_alarm; rx8010_rtc_ops.set_alarm = rx8010_set_alarm; rx8010_rtc_ops.alarm_irq_enable = rx8010_alarm_irq_enable; device_init_wakeup(&client->dev, 1); rx8010->rtc = devm_rtc_device_register(&client->dev, client->name, &rx8010_rtc_ops, THIS_MODULE); if (IS_ERR(rx8010->rtc)) { dev_err(&client->dev, "unable to register the class device\n"); return PTR_ERR(rx8010->rtc); }rx8010->rtc->max_user_freq = 1; return err; }static struct i2c_driver rx8010_driver = { .driver = { .name = "rtc-rx8010", .of_match_table = of_match_ptr(rx8010_of_match), }, .probe= rx8010_probe, .id_table= rx8010_id, }; module_i2c_driver(rx8010_driver); MODULE_AUTHOR("Akshay Bhat "); MODULE_DESCRIPTION("Epson RX8010SJ RTC driver"); MODULE_LICENSE("GPL v2");

改动部分：
左边是原生驱动，右边是修改部分。
改动一：

文章图片

寄存器地址0x31误写成0x32.
改动二：

文章图片

前面硬件的文章有提过，开机需要检查VLF是否被置位，如果是表示rtc还不能正常工作，需要置成0 ，然后再初始化才能工作，这样也是和数据手册上描述的上电流程是一致的。
改动三：

文章图片

由于驱动没用到irq,那么rx8010_probe()里的rx8010_rtc_ops结构体对应的read_alarm/set_alarm/alarm_irq_enable将不会被赋值，这将导致注册alarm驱动的时候失败。
alarmtimer.c

static int alarmtimer_rtc_add_device(struct device *dev, struct class_interface *class_intf) { unsigned long flags; struct rtc_device *rtc = to_rtc_device(dev); if (rtcdev) return -EBUSY; /*如果set_alarm是空函数会注册失败*/ if (!rtc->ops->set_alarm) return -1; if (!device_may_wakeup(rtc->dev.parent)) return -1; spin_lock_irqsave(&rtcdev_lock, flags); if (!rtcdev) { /*最终得到一个全局的rtcdev*/ rtcdev = rtc; /* hold a reference so it doesn't go away */ get_device(dev); } spin_unlock_irqrestore(&rtcdev_lock, flags); return 0; }

同样的 device_init_wakeup(&client->dev, 1); 是为了让device_may_wakeup(rtc->dev.parent) 不会返回失败。
这样才设置时间的时候就可以正确地得到rtc device了。
alarm-dev.c

static int alarm_set_rtc(struct timespec *ts) { ...... rtc_dev = alarmtimer_get_rtcdev(); /*这样得到就不会为NULL了。*/ if (rtc_dev) rv = rtc_set_time(rtc_dev, &new_rtc_tm); ...... }

参考：
【[RK3288][Android6.0] RTC模块RX8010SJ驱动添加及改动】https://raw.githubusercontent.com/torvalds/linux/master/drivers/rtc/rtc-rx8010.c

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• [RK3288][Android6.0] RTC驱动的上层调用流程