Introduce rtc-pcf85063 and rtc_sync kernel modules

linux_kernel_modules/rtc-pcf85063/README.md

+RTC-PCF85063 Linux Kernel Driver
+==========================
+
+This version of the RTC-PCF85063 Linux kernel driver was extracted from the mainline kernel at tag v4.9.125. The content were copied from `drivers/rtc/rtc-pcf85063.c`.

linux_kernel_modules/rtc-pcf85063/rtc-pcf85063.c

+/*
+ * An I2C driver for the PCF85063 RTC
+ * Copyright 2014 Rose Technology
+ *
+ * Author: Søren Andersen <san@rosetechnology.dk>
+ * Maintainers: http://www.nslu2-linux.org/
+ *
+ * based on the other drivers in this same directory.
+ *
+ * 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 <linux/i2c.h>
+#include <linux/bcd.h>
+#include <linux/rtc.h>
+#include <linux/module.h>
+
+/*
+ * Information for this driver was pulled from the following datasheets.
+ *
+ *  http://www.nxp.com/documents/data_sheet/PCF85063A.pdf
+ *  http://www.nxp.com/documents/data_sheet/PCF85063TP.pdf
+ *
+ *  PCF85063A -- Rev. 6 — 18 November 2015
+ *  PCF85063TP -- Rev. 4 — 6 May 2015
+*/
+
+#define PCF85063_REG_CTRL1		0x00 /* status */
+#define PCF85063_REG_CTRL1_STOP		BIT(5)
+#define PCF85063_REG_CTRL2		0x01
+
+#define PCF85063_REG_SC			0x04 /* datetime */
+#define PCF85063_REG_SC_OS		0x80
+#define PCF85063_REG_MN			0x05
+#define PCF85063_REG_HR			0x06
+#define PCF85063_REG_DM			0x07
+#define PCF85063_REG_DW			0x08
+#define PCF85063_REG_MO			0x09
+#define PCF85063_REG_YR			0x0A
+
+static struct i2c_driver pcf85063_driver;
+
+static int pcf85063_stop_clock(struct i2c_client *client, u8 *ctrl1)
+{
+	s32 ret;
+
+	ret = i2c_smbus_read_byte_data(client, PCF85063_REG_CTRL1);
+	if (ret < 0) {
+		dev_err(&client->dev, "Failing to stop the clock\n");
+		return -EIO;
+	}
+
+	/* stop the clock */
+	ret |= PCF85063_REG_CTRL1_STOP;
+
+	ret = i2c_smbus_write_byte_data(client, PCF85063_REG_CTRL1, ret);
+	if (ret < 0) {
+		dev_err(&client->dev, "Failing to stop the clock\n");
+		return -EIO;
+	}
+
+	*ctrl1 = ret;
+
+	return 0;
+}
+
+static int pcf85063_start_clock(struct i2c_client *client, u8 ctrl1)
+{
+	s32 ret;
+
+	/* start the clock */
+	ctrl1 &= ~PCF85063_REG_CTRL1_STOP;
+
+	ret = i2c_smbus_write_byte_data(client, PCF85063_REG_CTRL1, ctrl1);
+	if (ret < 0) {
+		dev_err(&client->dev, "Failing to start the clock\n");
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static int pcf85063_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	int rc;
+	u8 regs[7];
+
+	/*
+	 * while reading, the time/date registers are blocked and not updated
+	 * anymore until the access is finished. To not lose a second
+	 * event, the access must be finished within one second. So, read all
+	 * time/date registers in one turn.
+	 */
+	rc = i2c_smbus_read_i2c_block_data(client, PCF85063_REG_SC,
+					   sizeof(regs), regs);
+	if (rc != sizeof(regs)) {
+		dev_err(&client->dev, "date/time register read error\n");
+		return -EIO;
+	}
+
+	/* if the clock has lost its power it makes no sense to use its time */
+	if (regs[0] & PCF85063_REG_SC_OS) {
+		dev_warn(&client->dev, "Power loss detected, invalid time\n");
+		return -EINVAL;
+	}
+
+	tm->tm_sec = bcd2bin(regs[0] & 0x7F);
+	tm->tm_min = bcd2bin(regs[1] & 0x7F);
+	tm->tm_hour = bcd2bin(regs[2] & 0x3F); /* rtc hr 0-23 */
+	tm->tm_mday = bcd2bin(regs[3] & 0x3F);
+	tm->tm_wday = regs[4] & 0x07;
+	tm->tm_mon = bcd2bin(regs[5] & 0x1F) - 1; /* rtc mn 1-12 */
+	tm->tm_year = bcd2bin(regs[6]);
+	tm->tm_year += 100;
+
+	return 0;
+}
+
+static int pcf85063_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	int rc;
+	u8 regs[7];
+	u8 ctrl1;
+
+	if ((tm->tm_year < 100) || (tm->tm_year > 199))
+		return -EINVAL;
+
+	/*
+	 * to accurately set the time, reset the divider chain and keep it in
+	 * reset state until all time/date registers are written
+	 */
+	rc = pcf85063_stop_clock(client, &ctrl1);
+	if (rc != 0)
+		return rc;
+
+	/* hours, minutes and seconds */
+	regs[0] = bin2bcd(tm->tm_sec) & 0x7F; /* clear OS flag */
+
+	regs[1] = bin2bcd(tm->tm_min);
+	regs[2] = bin2bcd(tm->tm_hour);
+
+	/* Day of month, 1 - 31 */
+	regs[3] = bin2bcd(tm->tm_mday);
+
+	/* Day, 0 - 6 */
+	regs[4] = tm->tm_wday & 0x07;
+
+	/* month, 1 - 12 */
+	regs[5] = bin2bcd(tm->tm_mon + 1);
+
+	/* year and century */
+	regs[6] = bin2bcd(tm->tm_year - 100);
+
+	/* write all registers at once */
+	rc = i2c_smbus_write_i2c_block_data(client, PCF85063_REG_SC,
+					    sizeof(regs), regs);
+	if (rc < 0) {
+		dev_err(&client->dev, "date/time register write error\n");
+		return rc;
+	}
+
+	/*
+	 * Write the control register as a separate action since the size of
+	 * the register space is different between the PCF85063TP and
+	 * PCF85063A devices.  The rollover point can not be used.
+	 */
+	rc = pcf85063_start_clock(client, ctrl1);
+	if (rc != 0)
+		return rc;
+
+	return 0;
+}
+
+static const struct rtc_class_ops pcf85063_rtc_ops = {
+	.read_time	= pcf85063_rtc_read_time,
+	.set_time	= pcf85063_rtc_set_time
+};
+
+static int pcf85063_probe(struct i2c_client *client,
+				const struct i2c_device_id *id)
+{
+	struct rtc_device *rtc;
+	int err;
+
+	dev_dbg(&client->dev, "%s\n", __func__);
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
+		return -ENODEV;
+
+	err = i2c_smbus_read_byte_data(client, PCF85063_REG_CTRL1);
+	if (err < 0) {
+		dev_err(&client->dev, "RTC chip is not present\n");
+		return err;
+	}
+
+	rtc = devm_rtc_device_register(&client->dev,
+				       pcf85063_driver.driver.name,
+				       &pcf85063_rtc_ops, THIS_MODULE);
+
+	return PTR_ERR_OR_ZERO(rtc);
+}
+
+static const struct i2c_device_id pcf85063_id[] = {
+	{ "pcf85063", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, pcf85063_id);
+
+#ifdef CONFIG_OF
+static const struct of_device_id pcf85063_of_match[] = {
+	{ .compatible = "nxp,pcf85063" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, pcf85063_of_match);
+#endif
+
+static struct i2c_driver pcf85063_driver = {
+	.driver		= {
+		.name	= "rtc-pcf85063",
+		.of_match_table = of_match_ptr(pcf85063_of_match),
+	},
+	.probe		= pcf85063_probe,
+	.id_table	= pcf85063_id,
+};
+
+module_i2c_driver(pcf85063_driver);
+
+MODULE_AUTHOR("Søren Andersen <san@rosetechnology.dk>");
+MODULE_DESCRIPTION("PCF85063 RTC driver");
+MODULE_LICENSE("GPL");

linux_kernel_modules/rtc-pcf85063/rtc-pcf85063.mdef

+sources:
+{
+    rtc-pcf85063.c
+}

linux_kernel_modules/rtc_sync/README.md

+RTC-SYNC KERNEL MODULE
+==========================
+
+The rtc_hctosys function was taken from this page: https://github.com/spotify/linux/blob/master/drivers/rtc/hctosys.c
+
+The systohc function was modified from Linux source code 'drivers/rtc/systohc.c' to fit 32-bit system
+
+The rest of the functions were written by Sierra Wireless

linux_kernel_modules/rtc_sync/rtc_sync.c

+/*
+ * rtc_sync.c: module that syncs system time with rtc time
+ * and vice versa with 10 seconds interval
+ *
+ * Copyright (C) 2018 Sierra Wireless.
+ *
+ * This file is licensed under the terms of the GNU General Public License
+ * version 2.  This program is licensed "as is" without any warranty of any
+ * kind, whether express or implied.
+ */
+
+/* IMPORTANT: the RTC only stores whole seconds. It is arbitrary
+ * whether it stores the most close value or the value with partial
+ * seconds truncated. However, it is important that we use it to store
+ * the truncated value. This is because otherwise it is necessary,
+ * in an rtc sync function, to read both xtime.tv_sec and
+ * xtime.tv_nsec. On some processors (i.e. ARM), an atomic read
+ * of >32bits is not possible. So storing the most close value would
+ * slow down the sync API. So here we have the truncated value and
+ * the best guess is to add 0.5s.
+ */
+
+#include <linux/module.h>
+#include <linux/rtc.h>
+#include <linux/timer.h>
+#include <linux/time.h>
+#include <linux/sched.h>
+#include <linux/kthread.h>
+
+static struct task_struct *time_check_thread;
+
+/*
+ * this function syncs system time with RTC when startup
+ * if there is valid time store in RTC static int rtc_hctosys(void)
+ */
+static int rtc_hctosys(void)
+{
+	int err;
+	struct rtc_time tm;
+	struct rtc_device *rtc = rtc_class_open("rtc1");
+	if (rtc == NULL) {
+		printk("%s: unable to open rtc device (rtc1) for rtc_hctosys\n",
+			__FILE__);
+		return -ENODEV;
+	}
+
+	err = rtc_read_time(rtc, &tm);
+	if (err == 0) {
+		err = rtc_valid_tm(&tm);
+		if (err == 0) {
+			struct timespec tv;
+
+			tv.tv_nsec = NSEC_PER_SEC >> 1;
+
+			rtc_tm_to_time(&tm, &tv.tv_sec);
+
+			do_settimeofday(&tv);
+
+			dev_info(rtc->dev.parent,
+				"setting system clock to "
+				"%d-%02d-%02d %02d:%02d:%02d UTC (%u)\n",
+				tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,
+				tm.tm_hour, tm.tm_min, tm.tm_sec,
+				(unsigned int) tv.tv_sec);
+		} else { 
+			dev_err(rtc->dev.parent,
+				"hctosys: invalid date/time\n");
+		}
+	} else {
+		dev_err(rtc->dev.parent,
+			"hctosys: unable to read the hardware clock\n");
+	}
+
+	rtc_class_close(rtc);
+
+	return 0;
+}
+
+/*systohc sets RTC with system time*/
+static int systohc(struct timespec now)
+{
+	struct rtc_device *rtc;
+	struct rtc_time tm;
+	int res = -ENODEV;
+	printk("Setting time to %lld\n", timespec_to_ns(&now));
+
+	if (now.tv_nsec < (NSEC_PER_SEC >> 1))
+		rtc_time_to_tm(now.tv_sec, &tm);
+	else
+		rtc_time_to_tm(now.tv_sec + 1, &tm);
+
+	rtc = rtc_class_open("rtc1");
+
+	if (rtc == NULL) {
+		printk("%s: unable to open rtc device (rtc1) for systohc\n",
+			__FILE__);
+		return res;
+	}
+
+	/* rtc_hctosys exclusively uses UTC, so we call set_time here,
+	* not set_mmss. */
+	if (rtc->ops && (rtc->ops->set_time || rtc->ops->set_mmss))
+		res = rtc_set_time(rtc, &tm);
+	rtc_class_close(rtc);
+
+	return res;
+}
+
+/*
+ * time_check chekcs if the system time has been modified during
+ * the last checking period by comparing the expected time after
+ * checking period with a time allowance static int time_check(void *data)
+ */
+static int time_check(void *data)
+{
+	while (!kthread_should_stop()) {
+		const long long expected_delta_ns = 10 * NSEC_PER_SEC;
+		long timeout = 10 * HZ;
+		struct timespec before;
+		struct timespec after;
+		long long delta_ns;
+
+		ktime_get_real_ts(&before);
+		while (timeout > 0)
+			timeout = schedule_timeout(timeout);
+		ktime_get_real_ts(&after);
+
+		delta_ns = timespec_to_ns(&after) - timespec_to_ns(&before);
+		if (abs64(delta_ns - expected_delta_ns) > 1 * NSEC_PER_SEC)
+			systohc(after);
+	}
+	return 0;
+}
+
+static int __init rtc_sync_init(void)
+{
+	rtc_hctosys();
+	time_check_thread = kthread_run(time_check, NULL, "check_time");
+	return 0;
+}
+
+static void __exit rtc_sync_exit(void)
+{
+	if (time_check_thread) {
+		kthread_stop(time_check_thread);
+	}
+}
+
+module_init(rtc_sync_init);
+module_exit(rtc_sync_exit);
+
+MODULE_DESCRIPTION("Syncs system time with rtc time when waked up from ULPM. Checks if system time has been changed during a given period, if changed, saves system time to rtc.");
+MODULE_LICENSE("GPL v2");
+

linux_kernel_modules/rtc_sync/rtc_sync.mdef

+sources:
+{
+    rtc_sync.c
+}
+
+requires:
+{
+    kernelModules:
+    {
+        $CURDIR/../rtc-pcf85063/rtc-pcf85063
+        $CURDIR/../mangoh/mangoh_yellow
+    }
+}