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// SPDX-License-Identifier: GPL-2.0
/*
* Nuvoton NCT6694 RTC driver based on USB interface.
*
* Copyright (C) 2025 Nuvoton Technology Corp.
*/
#include <linux/bcd.h>
#include <linux/irqdomain.h>
#include <linux/kernel.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
#define NCT6694_RTC_TIME_SEL 0x00
/* Command 01h - RTC Alarm */
#define NCT6694_RTC_ALARM 0x01
#define NCT6694_RTC_ALARM_SEL 0x00
/* Command 02h - RTC Status */
#define NCT6694_RTC_STATUS 0x02
#define NCT6694_RTC_STATUS_SEL 0x00
#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 __packed 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;
int irq;
};
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;
static const struct nct6694_cmd_header cmd_hd = {
.mod = NCT6694_RTC_MOD,
.cmd = NCT6694_RTC_TIME,
.sel = NCT6694_RTC_TIME_SEL,
.len = cpu_to_le16(sizeof(*time))
};
int ret;
ret = nct6694_read_msg(data->nct6694, &cmd_hd, 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;
static const struct nct6694_cmd_header cmd_hd = {
.mod = NCT6694_RTC_MOD,
.cmd = NCT6694_RTC_TIME,
.sel = NCT6694_RTC_TIME_SEL,
.len = cpu_to_le16(sizeof(*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, &cmd_hd, 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;
static const struct nct6694_cmd_header cmd_hd = {
.mod = NCT6694_RTC_MOD,
.cmd = NCT6694_RTC_ALARM,
.sel = NCT6694_RTC_ALARM_SEL,
.len = cpu_to_le16(sizeof(*alarm))
};
int ret;
ret = nct6694_read_msg(data->nct6694, &cmd_hd, 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;
static const struct nct6694_cmd_header cmd_hd = {
.mod = NCT6694_RTC_MOD,
.cmd = NCT6694_RTC_ALARM,
.sel = NCT6694_RTC_ALARM_SEL,
.len = cpu_to_le16(sizeof(*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, &cmd_hd, 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;
static const struct nct6694_cmd_header cmd_hd = {
.mod = NCT6694_RTC_MOD,
.cmd = NCT6694_RTC_STATUS,
.sel = NCT6694_RTC_STATUS_SEL,
.len = cpu_to_le16(sizeof(*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, &cmd_hd, 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;
static const struct nct6694_cmd_header cmd_hd = {
.mod = NCT6694_RTC_MOD,
.cmd = NCT6694_RTC_STATUS,
.sel = NCT6694_RTC_STATUS_SEL,
.len = cpu_to_le16(sizeof(*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, &cmd_hd, 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 void nct6694_irq_dispose_mapping(void *d)
{
struct nct6694_rtc_data *data = d;
irq_dispose_mapping(data->irq);
}
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;
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->irq = irq_create_mapping(nct6694->domain, NCT6694_IRQ_RTC);
if (!data->irq)
return -EINVAL;
ret = devm_add_action_or_reset(&pdev->dev, nct6694_irq_dispose_mapping,
data);
if (ret)
return ret;
ret = devm_device_init_wakeup(&pdev->dev);
if (ret)
return dev_err_probe(&pdev->dev, ret, "Failed to init wakeup\n");
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, data->irq, NULL,
nct6694_irq, IRQF_ONESHOT,
"rtc-nct6694", data);
if (ret < 0)
return dev_err_probe(&pdev->dev, ret, "Failed to request irq\n");
return devm_rtc_register_device(data->rtc);
}
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@nuvoton.com>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:nct6694-rtc");