[v1,9/9] rtc: Add Nuvoton NCT6694 RTC support

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

Signed-off-by: Ming Yu <tmyu0@nuvoton.com>
---
 MAINTAINERS               |   1 +
 drivers/rtc/Kconfig       |  10 ++
 drivers/rtc/Makefile      |   1 +
 drivers/rtc/rtc-nct6694.c | 276 ++++++++++++++++++++++++++++++++++++++
 4 files changed, 288 insertions(+)
 create mode 100644 drivers/rtc/rtc-nct6694.c

Hello,

2024年10月24日(木) 18:04 Ming Yu <a0282524688@gmail.com>:
>
> This driver supports RTC functionality for NCT6694 MFD device
> based on USB interface.
>
> Signed-off-by: Ming Yu <tmyu0@nuvoton.com>
> ---
>  MAINTAINERS               |   1 +
>  drivers/rtc/Kconfig       |  10 ++
>  drivers/rtc/Makefile      |   1 +
>  drivers/rtc/rtc-nct6694.c | 276 ++++++++++++++++++++++++++++++++++++++
>  4 files changed, 288 insertions(+)
>  create mode 100644 drivers/rtc/rtc-nct6694.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 4d5a5eded3b9..8de90bda8b5e 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -16445,6 +16445,7 @@ F:      drivers/i2c/busses/i2c-nct6694.c
>  F:     drivers/mfd/nct6694.c
>  F:     drivers/net/can/nct6694_canfd.c
>  F:     drivers/pwm/pwm-nct6694.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 66eb1122248b..240c496d95f7 100644
> --- a/drivers/rtc/Kconfig
> +++ b/drivers/rtc/Kconfig
> @@ -406,6 +406,16 @@ 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 f62340ecc534..64443d26bb5b 100644
> --- a/drivers/rtc/Makefile
> +++ b/drivers/rtc/Makefile
> @@ -116,6 +116,7 @@ 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..622bb9fbe6f6
> --- /dev/null
> +++ b/drivers/rtc/rtc-nct6694.c
> @@ -0,0 +1,276 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Nuvoton NCT6694 RTC driver based on USB interface.
> + *
> + * Copyright (C) 2024 Nuvoton Technology Corp.
> + */
> +
> +#include <linux/slab.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/rtc.h>
> +#include <linux/bcd.h>
> +#include <linux/platform_device.h>
> +#include <linux/mfd/nct6694.h>

Please sort header files alphabetically.

> +
> +#define DRVNAME "nct6694-rtc"
> +
> +/* Host interface */
> +#define REQUEST_RTC_MOD                0x08
> +
> +/* Message Channel */
> +/* Command 00h */
> +#define REQUEST_RTC_CMD0_LEN   0x07
> +#define REQUEST_RTC_CMD0_OFFSET        0x0000  /* OFFSET = SEL|CMD */
> +#define RTC_SEC_IDX            0x00
> +#define RTC_MIN_IDX            0x01
> +#define RTC_HOUR_IDX           0x02
> +#define RTC_WEEK_IDX           0x03
> +#define RTC_DAY_IDX            0x04
> +#define RTC_MONTH_IDX          0x05
> +#define RTC_YEAR_IDX           0x06
> +/* Command 01h */
> +#define REQUEST_RTC_CMD1_LEN   0x05
> +#define REQUEST_RTC_CMD1_OFFSET        0x0001  /* OFFSET = SEL|CMD */
> +#define RTC_ALRM_EN_IDX                0x03
> +#define RTC_ALRM_PEND_IDX      0x04
> +/* Command 02h */
> +#define REQUEST_RTC_CMD2_LEN   0x02
> +#define REQUEST_RTC_CMD2_OFFSET        0x0002  /* OFFSET = SEL|CMD */
> +#define RTC_IRQ_EN_IDX         0x00
> +#define RTC_IRQ_PEND_IDX       0x01
> +
> +#define RTC_IRQ_EN             (BIT(0) | BIT(5))

RTC_IRQ_INT_EN | RTC_IRQ_GPO_EN ?

> +#define RTC_IRQ_INT_EN         BIT(0)  /* Transmit a USB INT-in when RTC alarm */
> +#define RTC_IRQ_GPO_EN         BIT(5)  /* Trigger a GPO Low Pulse when RTC alarm */
> +#define RTC_IRQ_STS            BIT(0)  /* Write 1 clear IRQ status */
> +
> +struct nct6694_rtc_data {
> +       struct nct6694 *nct6694;
> +       struct rtc_device *rtc;
> +       struct work_struct alarm_work;
> +};
> +
> +static int nct6694_rtc_read_time(struct device *dev, struct rtc_time *tm)
> +{
> +       struct nct6694_rtc_data *data = dev_get_drvdata(dev);
> +       unsigned char buf[REQUEST_RTC_CMD0_LEN];
> +       int ret;
> +
> +       ret = nct6694_read_msg(data->nct6694, REQUEST_RTC_MOD,
> +                              REQUEST_RTC_CMD0_OFFSET, REQUEST_RTC_CMD0_LEN,
> +                              0, REQUEST_RTC_CMD0_LEN, buf);
> +       if (ret) {
> +               pr_err("%s: Failed to get rtc device!\n", __func__);
> +               return -EIO;
> +       }
> +
> +       tm->tm_sec = bcd2bin(buf[RTC_SEC_IDX]);         /* tm_sec expect 0 ~ 59 */
> +       tm->tm_min = bcd2bin(buf[RTC_MIN_IDX]);         /* tm_min expect 0 ~ 59 */
> +       tm->tm_hour = bcd2bin(buf[RTC_HOUR_IDX]);       /* tm_hour expect 0 ~ 23 */
> +       tm->tm_wday = bcd2bin(buf[RTC_WEEK_IDX]) - 1;   /* tm_wday expect 0 ~ 6 */
> +       tm->tm_mday = bcd2bin(buf[RTC_DAY_IDX]);        /* tm_mday expect 1 ~ 31 */
> +       tm->tm_mon = bcd2bin(buf[RTC_MONTH_IDX]) - 1;   /* tm_month expect 0 ~ 11 */
> +       tm->tm_year = bcd2bin(buf[RTC_YEAR_IDX]) + 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);
> +       unsigned char buf[REQUEST_RTC_CMD0_LEN];
> +       int ret;
> +
> +       buf[RTC_SEC_IDX] = bin2bcd(tm->tm_sec);
> +       buf[RTC_MIN_IDX] = bin2bcd(tm->tm_min);
> +       buf[RTC_HOUR_IDX] = bin2bcd(tm->tm_hour);
> +       buf[RTC_WEEK_IDX] = bin2bcd(tm->tm_wday + 1);
> +       buf[RTC_DAY_IDX] = bin2bcd(tm->tm_mday);
> +       buf[RTC_MONTH_IDX] = bin2bcd(tm->tm_mon + 1);
> +       buf[RTC_YEAR_IDX] = bin2bcd(tm->tm_year - 100);
> +
> +       ret = nct6694_write_msg(data->nct6694, REQUEST_RTC_MOD,
> +                               REQUEST_RTC_CMD0_OFFSET, REQUEST_RTC_CMD0_LEN,
> +                               buf);
> +       if (ret) {
> +               pr_err("%s: Failed to set rtc device!\n", __func__);
> +               return -EIO;

Why do you return -EIO? Please do not overwrite error codes.

> +       }
> +
> +       return ret;
> +}
> +
> +static int nct6694_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
> +{
> +       struct nct6694_rtc_data *data = dev_get_drvdata(dev);
> +       unsigned char buf[REQUEST_RTC_CMD1_LEN];
> +       int ret;
> +
> +       ret = nct6694_read_msg(data->nct6694, REQUEST_RTC_MOD,
> +                              REQUEST_RTC_CMD1_OFFSET, REQUEST_RTC_CMD1_LEN,
> +                              0, REQUEST_RTC_CMD1_LEN, buf);
> +       if (ret) {
> +               pr_err("%s: Failed to get rtc device!\n", __func__);
> +               return -EIO;

same as above.

> +       }
> +
> +       alrm->time.tm_sec = bcd2bin(buf[RTC_SEC_IDX]);
> +       alrm->time.tm_min = bcd2bin(buf[RTC_MIN_IDX]);
> +       alrm->time.tm_hour = bcd2bin(buf[RTC_HOUR_IDX]);
> +
> +       alrm->enabled = buf[RTC_ALRM_EN_IDX];
> +       alrm->pending = buf[RTC_ALRM_PEND_IDX];
> +
> +       return ret;
> +}
> +
> +static int nct6694_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
> +{
> +       struct nct6694_rtc_data *data = dev_get_drvdata(dev);
> +       unsigned char buf[REQUEST_RTC_CMD1_LEN];
> +       int ret;
> +
> +       buf[RTC_SEC_IDX] = bin2bcd(alrm->time.tm_sec);
> +       buf[RTC_MIN_IDX] = bin2bcd(alrm->time.tm_min);
> +       buf[RTC_HOUR_IDX] = bin2bcd(alrm->time.tm_hour);
> +       buf[RTC_ALRM_EN_IDX] = alrm->enabled ? RTC_IRQ_EN : 0;
> +       buf[RTC_ALRM_PEND_IDX] = 0;
> +
> +       ret = nct6694_write_msg(data->nct6694, REQUEST_RTC_MOD,
> +                               REQUEST_RTC_CMD1_OFFSET, REQUEST_RTC_CMD1_LEN,
> +                               buf);
> +       if (ret) {
> +               pr_err("%s: Failed to set rtc device!\n", __func__);
> +               return -EIO;

same as above.

> +       }
> +
> +       return ret;
> +}
> +
> +static int nct6694_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
> +{
> +       struct nct6694_rtc_data *data = dev_get_drvdata(dev);
> +       unsigned char buf[REQUEST_RTC_CMD2_LEN] = {0};
> +       int ret;
> +
> +       if (enabled)
> +               buf[RTC_IRQ_EN_IDX] |= RTC_IRQ_EN;
> +       else
> +               buf[RTC_IRQ_EN_IDX] &= ~RTC_IRQ_EN;
> +
> +       ret = nct6694_write_msg(data->nct6694, REQUEST_RTC_MOD,
> +                               REQUEST_RTC_CMD2_OFFSET, REQUEST_RTC_CMD2_LEN,
> +                               buf);
> +       if (ret) {
> +               pr_err("%s: Failed to set rtc device!\n", __func__);
> +               return -EIO;

same as above.

> +       }
> +
> +       return ret;
> +}
> +
> +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 void nct6694_rtc_alarm(struct work_struct *work)
> +{
> +       struct nct6694_rtc_data *data;
> +       unsigned char buf[REQUEST_RTC_CMD2_LEN] = {0};
> +
> +       data = container_of(work, struct nct6694_rtc_data, alarm_work);
> +
> +       pr_info("%s: Got RTC alarm!\n", __func__);
> +       buf[RTC_IRQ_EN_IDX] = RTC_IRQ_EN;
> +       buf[RTC_IRQ_PEND_IDX] = RTC_IRQ_STS;
> +       nct6694_write_msg(data->nct6694, REQUEST_RTC_MOD,
> +                         REQUEST_RTC_CMD2_OFFSET,
> +                         REQUEST_RTC_CMD2_LEN, buf);
> +}
> +
> +static void nct6694_rtc_handler(void *private_data)
> +{
> +       struct nct6694_rtc_data *data = private_data;
> +       struct nct6694 *nct6694 = data->nct6694;
> +
> +       queue_work(nct6694->async_workqueue, &data->alarm_work);
> +}
> +
> +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->rtc = devm_rtc_allocate_device(&pdev->dev);
> +       if (IS_ERR(data->rtc))
> +               return PTR_ERR(data->rtc);

Please use dev_err_probe.

> +
> +       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;
> +
> +       INIT_WORK(&data->alarm_work, nct6694_rtc_alarm);
> +
> +       ret = nct6694_register_handler(nct6694, RTC_IRQ_STATUS,
> +                                      nct6694_rtc_handler, data);
> +       if (ret) {
> +               dev_err(&pdev->dev, "%s:  Failed to register handler: %pe\n",
> +                       __func__, ERR_PTR(ret));

Please use dev_err_probe.

> +               return ret;
> +       }
> +
> +       device_set_wakeup_capable(&pdev->dev, 1);
> +
> +       platform_set_drvdata(pdev, data);
> +
> +       /* Register rtc device to RTC framework */
> +       ret = devm_rtc_register_device(data->rtc);
> +       if (ret) {
> +               dev_err(&pdev->dev, "Failed to register rtc device!\n");
> +               return ret;
> +       }

You can simplify return devm_rtc_register_device.

> +
> +       return 0;
> +}
> +
> +static struct platform_driver nct6694_rtc_driver = {
> +       .driver = {
> +               .name   = DRVNAME,
> +       },
> +       .probe          = nct6694_rtc_probe,
> +};
> +
> +static int __init nct6694_init(void)
> +{
> +       int err;
> +
> +       err = platform_driver_register(&nct6694_rtc_driver);
> +       if (!err) {
> +               if (err)

This looks strange. You can simplify return platform_driver_register.

> +                       platform_driver_unregister(&nct6694_rtc_driver);
> +       }
> +
> +       return err;
> +}
> +subsys_initcall(nct6694_init);
> +
> +static void __exit nct6694_exit(void)
> +{
> +       platform_driver_unregister(&nct6694_rtc_driver);
> +}
> +module_exit(nct6694_exit);
> +
> +MODULE_DESCRIPTION("USB-RTC driver for NCT6694");
> +MODULE_AUTHOR("Ming Yu <tmyu0@nuvoton.com>");
> +MODULE_LICENSE("GPL");
> --
> 2.34.1
>
>

Best regards,
  Nobuhiro