Message-Id: <20241227095727.2401257-8-a0282524688@gmail.com>
Date: Fri, 27 Dec 2024 17:57:27 +0800
From: Ming Yu <a0282524688@...il.com>
To: tmyu0@...oton.com,
	lee@...nel.org,
	linus.walleij@...aro.org,
	brgl@...ev.pl,
	andi.shyti@...nel.org,
	mkl@...gutronix.de,
	mailhol.vincent@...adoo.fr,
	andrew+netdev@...n.ch,
	davem@...emloft.net,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com,
	wim@...ux-watchdog.org,
	linux@...ck-us.net,
	jdelvare@...e.com,
	alexandre.belloni@...tlin.com
Cc: linux-kernel@...r.kernel.org,
	linux-gpio@...r.kernel.org,
	linux-i2c@...r.kernel.org,
	linux-can@...r.kernel.org,
	netdev@...r.kernel.org,
	linux-watchdog@...r.kernel.org,
	linux-hwmon@...r.kernel.org,
	linux-rtc@...r.kernel.org,
	Ming Yu <a0282524688@...il.com>
Subject: [PATCH v4 7/7] rtc: Add Nuvoton NCT6694 RTC support

This driver supports RTC functionality for NCT6694 MFD device
based on USB interface.

Signed-off-by: Ming Yu <a0282524688@...il.com>
---
 MAINTAINERS               |   1 +
 drivers/rtc/Kconfig       |  10 ++
 drivers/rtc/Makefile      |   1 +
 drivers/rtc/rtc-nct6694.c | 263 ++++++++++++++++++++++++++++++++++++++
 4 files changed, 275 insertions(+)
 create mode 100644 drivers/rtc/rtc-nct6694.c

diff --git a/MAINTAINERS b/MAINTAINERS
index e5c65e382141..6a5164e42700 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -16731,6 +16731,7 @@ F:	drivers/hwmon/nct6694-hwmon.c
 F:	drivers/i2c/busses/i2c-nct6694.c
 F:	drivers/mfd/nct6694.c
 F:	drivers/net/can/nct6694_canfd.c
+F:	drivers/rtc/rtc-nct6694.c
 F:	drivers/watchdog/nct6694_wdt.c
 F:	include/linux/mfd/nct6694.h
 
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index a60bcc791a48..aeab67acbc84 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -416,6 +416,16 @@ config RTC_DRV_NCT3018Y
 	   This driver can also be built as a module, if so, the module will be
 	   called "rtc-nct3018y".
 
+config RTC_DRV_NCT6694
+	tristate "Nuvoton NCT6694 RTC support"
+	depends on MFD_NCT6694
+	help
+	  If you say yes to this option, support will be included for Nuvoton
+	  NCT6694, a USB device to RTC.
+
+	  This driver can also be built as a module. If so, the module will
+	  be called rtc-nct6694.
+
 config RTC_DRV_RK808
 	tristate "Rockchip RK805/RK808/RK809/RK817/RK818 RTC"
 	depends on MFD_RK8XX
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 489b4ab07068..d0d6f4a4972e 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -118,6 +118,7 @@ obj-$(CONFIG_RTC_DRV_MXC)	+= rtc-mxc.o
 obj-$(CONFIG_RTC_DRV_MXC_V2)	+= rtc-mxc_v2.o
 obj-$(CONFIG_RTC_DRV_GAMECUBE)	+= rtc-gamecube.o
 obj-$(CONFIG_RTC_DRV_NCT3018Y)	+= rtc-nct3018y.o
+obj-$(CONFIG_RTC_DRV_NCT6694)	+= rtc-nct6694.o
 obj-$(CONFIG_RTC_DRV_NTXEC)	+= rtc-ntxec.o
 obj-$(CONFIG_RTC_DRV_OMAP)	+= rtc-omap.o
 obj-$(CONFIG_RTC_DRV_OPAL)	+= rtc-opal.o
diff --git a/drivers/rtc/rtc-nct6694.c b/drivers/rtc/rtc-nct6694.c
new file mode 100644
index 000000000000..9465ab895c6d
--- /dev/null
+++ b/drivers/rtc/rtc-nct6694.c
@@ -0,0 +1,263 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Nuvoton NCT6694 RTC driver based on USB interface.
+ *
+ * Copyright (C) 2024 Nuvoton Technology Corp.
+ */
+
+#include <linux/bcd.h>
+#include <linux/irqdomain.h>
+#include <linux/kernel.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/nct6694.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+#include <linux/slab.h>
+
+/*
+ * USB command module type for NCT6694 RTC controller.
+ * This defines the module type used for communication with the NCT6694
+ * RTC controller over the USB interface.
+ */
+#define NCT6694_RTC_MOD		0x08
+
+/* Command 00h - RTC Time */
+#define NCT6694_RTC_TIME	0x0000	/* SEL|CMD */
+/* Command 01h - RTC Alarm */
+#define NCT6694_RTC_ALARM	0x0001	/* SEL|CMD */
+/* Command 02h - RTC Status */
+#define NCT6694_RTC_STATUS	0x0002	/* SEL|CMD */
+
+#define NCT6694_RTC_IRQ_INT_EN	BIT(0)	/* Transmit a USB INT-in when RTC alarm */
+#define NCT6694_RTC_IRQ_GPO_EN	BIT(5)	/* Trigger a GPO Low Pulse when RTC alarm */
+
+#define NCT6694_RTC_IRQ_EN	(NCT6694_RTC_IRQ_INT_EN | NCT6694_RTC_IRQ_GPO_EN)
+#define NCT6694_RTC_IRQ_STS	BIT(0)	/* Write 1 clear IRQ status */
+
+struct __packed nct6694_rtc_time {
+	u8 sec;
+	u8 min;
+	u8 hour;
+	u8 week;
+	u8 day;
+	u8 month;
+	u8 year;
+};
+
+struct __packed nct6694_rtc_alarm {
+	u8 sec;
+	u8 min;
+	u8 hour;
+	u8 alarm_en;
+	u8 alarm_pend;
+};
+
+struct __packed nct6694_rtc_status {
+	u8 irq_en;
+	u8 irq_pend;
+};
+
+union nct6694_rtc_msg {
+	struct nct6694_rtc_time time;
+	struct nct6694_rtc_alarm alarm;
+	struct nct6694_rtc_status sts;
+};
+
+struct nct6694_rtc_data {
+	struct nct6694 *nct6694;
+	struct rtc_device *rtc;
+	union nct6694_rtc_msg *msg;
+};
+
+static int nct6694_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct nct6694_rtc_data *data = dev_get_drvdata(dev);
+	struct nct6694_rtc_time *time = &data->msg->time;
+	int ret;
+
+	ret = nct6694_read_msg(data->nct6694, NCT6694_RTC_MOD,
+			       NCT6694_RTC_TIME,
+			       sizeof(*time),
+			       time);
+	if (ret)
+		return ret;
+
+	tm->tm_sec = bcd2bin(time->sec);                /* tm_sec expect 0 ~ 59 */
+	tm->tm_min = bcd2bin(time->min);                /* tm_min expect 0 ~ 59 */
+	tm->tm_hour = bcd2bin(time->hour);              /* tm_hour expect 0 ~ 23 */
+	tm->tm_wday = bcd2bin(time->week) - 1;          /* tm_wday expect 0 ~ 6 */
+	tm->tm_mday = bcd2bin(time->day);               /* tm_mday expect 1 ~ 31 */
+	tm->tm_mon = bcd2bin(time->month) - 1;          /* tm_month expect 0 ~ 11 */
+	tm->tm_year = bcd2bin(time->year) + 100;        /* tm_year expect since 1900 */
+
+	return ret;
+}
+
+static int nct6694_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct nct6694_rtc_data *data = dev_get_drvdata(dev);
+	struct nct6694_rtc_time *time = &data->msg->time;
+
+	time->sec = bin2bcd(tm->tm_sec);
+	time->min = bin2bcd(tm->tm_min);
+	time->hour = bin2bcd(tm->tm_hour);
+	time->week = bin2bcd(tm->tm_wday + 1);
+	time->day = bin2bcd(tm->tm_mday);
+	time->month = bin2bcd(tm->tm_mon + 1);
+	time->year = bin2bcd(tm->tm_year - 100);
+
+	return nct6694_write_msg(data->nct6694, NCT6694_RTC_MOD,
+				 NCT6694_RTC_TIME,
+				 sizeof(*time),
+				 time);
+}
+
+static int nct6694_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct nct6694_rtc_data *data = dev_get_drvdata(dev);
+	struct nct6694_rtc_alarm *alarm = &data->msg->alarm;
+	int ret;
+
+	ret = nct6694_read_msg(data->nct6694, NCT6694_RTC_MOD,
+			       NCT6694_RTC_ALARM,
+			       sizeof(*alarm),
+			       alarm);
+	if (ret)
+		return ret;
+
+	alrm->time.tm_sec = bcd2bin(alarm->sec);
+	alrm->time.tm_min = bcd2bin(alarm->min);
+	alrm->time.tm_hour = bcd2bin(alarm->hour);
+	alrm->enabled = alarm->alarm_en;
+	alrm->pending = alarm->alarm_pend;
+
+	return ret;
+}
+
+static int nct6694_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct nct6694_rtc_data *data = dev_get_drvdata(dev);
+	struct nct6694_rtc_alarm *alarm = &data->msg->alarm;
+
+	alarm->sec = bin2bcd(alrm->time.tm_sec);
+	alarm->min = bin2bcd(alrm->time.tm_min);
+	alarm->hour = bin2bcd(alrm->time.tm_hour);
+	alarm->alarm_en = alrm->enabled ? NCT6694_RTC_IRQ_EN : 0;
+	alarm->alarm_pend = 0;
+
+	return nct6694_write_msg(data->nct6694, NCT6694_RTC_MOD,
+				 NCT6694_RTC_ALARM,
+				 sizeof(*alarm),
+				 alarm);
+}
+
+static int nct6694_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
+{
+	struct nct6694_rtc_data *data = dev_get_drvdata(dev);
+	struct nct6694_rtc_status *sts = &data->msg->sts;
+
+	if (enabled)
+		sts->irq_en |= NCT6694_RTC_IRQ_EN;
+	else
+		sts->irq_en &= ~NCT6694_RTC_IRQ_EN;
+
+	sts->irq_pend = 0;
+
+	return nct6694_write_msg(data->nct6694, NCT6694_RTC_MOD,
+				 NCT6694_RTC_STATUS,
+				 sizeof(*sts),
+				 sts);
+}
+
+static const struct rtc_class_ops nct6694_rtc_ops = {
+	.read_time = nct6694_rtc_read_time,
+	.set_time = nct6694_rtc_set_time,
+	.read_alarm = nct6694_rtc_read_alarm,
+	.set_alarm = nct6694_rtc_set_alarm,
+	.alarm_irq_enable = nct6694_rtc_alarm_irq_enable,
+};
+
+static irqreturn_t nct6694_irq(int irq, void *dev_id)
+{
+	struct nct6694_rtc_data *data = dev_id;
+	struct nct6694_rtc_status *sts = &data->msg->sts;
+	int ret;
+
+	rtc_lock(data->rtc);
+
+	sts->irq_en = NCT6694_RTC_IRQ_EN;
+	sts->irq_pend = NCT6694_RTC_IRQ_STS;
+	ret = nct6694_write_msg(data->nct6694, NCT6694_RTC_MOD,
+				NCT6694_RTC_STATUS,
+				sizeof(*sts),
+				sts);
+	if (ret) {
+		rtc_unlock(data->rtc);
+		return IRQ_NONE;
+	}
+
+	rtc_update_irq(data->rtc, 1, RTC_IRQF | RTC_AF);
+
+	rtc_unlock(data->rtc);
+
+	return IRQ_HANDLED;
+}
+
+static int nct6694_rtc_probe(struct platform_device *pdev)
+{
+	struct nct6694_rtc_data *data;
+	struct nct6694 *nct6694 = dev_get_drvdata(pdev->dev.parent);
+	int ret, irq;
+
+	irq = irq_create_mapping(nct6694->domain, NCT6694_IRQ_RTC);
+	if (!irq)
+		return -EINVAL;
+
+	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->msg = devm_kzalloc(&pdev->dev, sizeof(union nct6694_rtc_msg),
+				 GFP_KERNEL);
+	if (!data->msg)
+		return -ENOMEM;
+
+	data->rtc = devm_rtc_allocate_device(&pdev->dev);
+	if (IS_ERR(data->rtc))
+		return PTR_ERR(data->rtc);
+
+	data->nct6694 = nct6694;
+	data->rtc->ops = &nct6694_rtc_ops;
+	data->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
+	data->rtc->range_max = RTC_TIMESTAMP_END_2099;
+
+	platform_set_drvdata(pdev, data);
+
+	ret = devm_request_threaded_irq(&pdev->dev, irq, NULL,
+					nct6694_irq, IRQF_ONESHOT,
+					"nct6694-rtc", data);
+	if (ret < 0)
+		return dev_err_probe(&pdev->dev, ret, "Failed to request irq\n");
+
+	ret = devm_rtc_register_device(data->rtc);
+	if (ret)
+		return dev_err_probe(&pdev->dev, ret, "Failed to register rtc\n");
+
+	device_init_wakeup(&pdev->dev, true);
+	return 0;
+}
+
+static struct platform_driver nct6694_rtc_driver = {
+	.driver = {
+		.name	= "nct6694-rtc",
+	},
+	.probe		= nct6694_rtc_probe,
+};
+
+module_platform_driver(nct6694_rtc_driver);
+
+MODULE_DESCRIPTION("USB-RTC driver for NCT6694");
+MODULE_AUTHOR("Ming Yu <tmyu0@...oton.com>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:nct6694-rtc");
-- 
2.34.1

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