[PATCH 3/4] rtc: bbnsm: Add the bbnsm rtc support

[Jacky Bai]

> Subject: Re: [PATCH 3/4] rtc: bbnsm: Add the bbnsm rtc support
> 
> On 21/11/2022 14:51:43+0800, Jacky Bai wrote:
> > The BBNSM module includes a real time counter with alarm.
> > Add a RTC driver for this function.
> >
> > Signed-off-by: Jacky Bai <ping.bai at nxp.com>
> > Reviewed-by: Peng Fan <peng.fan at nxp.com>
> > ---
> >  drivers/rtc/Kconfig     |  12 +++
> >  drivers/rtc/Makefile    |   1 +
> >  drivers/rtc/rtc-bbnsm.c | 223
> > ++++++++++++++++++++++++++++++++++++++++
> 
> I'd prefer that filename to include imx or mxc if this is only available on those
> SoCs.
>

For now, it is used on i.MX SoC, not sure if it will be used on NXP other SoC. I will
update the file name to include 'imx' in v2.

> > diff --git a/drivers/rtc/rtc-bbnsm.c b/drivers/rtc/rtc-bbnsm.c new
> > file mode 100644 index 000000000000..4157b238ed9a
> > --- /dev/null
> > +++ b/drivers/rtc/rtc-bbnsm.c
> > @@ -0,0 +1,223 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +//
> > +// Copyright 2022 NXP.
> > +
> > +#include <linux/init.h>
> > +#include <linux/io.h>
> > +#include <linux/kernel.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/pm_wakeirq.h>
> > +#include <linux/rtc.h>
> > +#include <linux/mfd/syscon.h>
> > +#include <linux/regmap.h>
> 
> This list should be sorted alphabetically
> 

Thx, will fix it in V2.

> 
> > +
> > +#define BBNSM_CTRL	0x8
> > +#define BBNSM_INT_EN	0x10
> > +#define BBNSM_EVENTS	0x14
> > +#define BBNSM_RTC_LS	0x40
> > +#define BBNSM_RTC_MS	0x44
> > +#define BBNSM_TA	0x50
> > +
> > +#define RTC_EN		0x2
> > +#define RTC_EN_MSK	0x3
> > +#define TA_EN		(0x2 << 2)
> > +#define TA_DIS		(0x1 << 2)
> > +#define TA_EN_MSK	(0x3 << 2)
> > +#define RTC_INT_EN	0x2
> > +#define TA_INT_EN	(0x2 << 2)
> > +
> > +#define BBNSM_EVENT_TA	TA_EN
> > +
> 
> I'm not clear why this define is needed

This define is for RTC alarm event status check, as it use the same bitfield offset as TA_EN,
I just did the above define. It seems introduce some unnecessary confusion. 

> 
> > +static irqreturn_t bbnsm_rtc_irq_handler(int irq, void *dev_id) {
> > +	struct device *dev = dev_id;
> > +	struct bbnsm_rtc  *bbnsm = dev_get_drvdata(dev);
> > +	u32 val;
> > +	u32 event = 0;
> 
> You can rework this function to remove this variable because it is either 0 or
> RTC_AF | RTC_IRQF
> 

Ok, will refine in V2.

> > +
> > +	regmap_read(bbnsm->regmap, BBNSM_EVENTS, &val);
> > +	if (val & BBNSM_EVENT_TA) {
> > +		event |= (RTC_AF | RTC_IRQF);
> > +		bbnsm_rtc_alarm_irq_enable(dev, false);
> > +		/* clear the alarm event */
> > +		regmap_write_bits(bbnsm->regmap, BBNSM_EVENTS, TA_EN_MSK,
> BBNSM_EVENT_TA);
> > +		rtc_update_irq(bbnsm->rtc, 1, event);
> > +	}
> > +
> > +	return event ? IRQ_HANDLED : IRQ_NONE; }
> > +
> > +static int bbnsm_rtc_probe(struct platform_device *pdev) {
> > +	struct bbnsm_rtc *bbnsm;
> > +	int ret;
> > +
> > +	bbnsm = devm_kzalloc(&pdev->dev, sizeof(*bbnsm), GFP_KERNEL);
> > +	if (!bbnsm)
> > +		return -ENOMEM;
> > +
> > +	bbnsm->rtc = devm_rtc_allocate_device(&pdev->dev);
> > +
> > +	bbnsm->regmap =
> syscon_regmap_lookup_by_phandle(pdev->dev.of_node, "regmap");
> > +	if (IS_ERR(bbnsm->regmap)) {
> > +		dev_err(&pdev->dev, "bbnsm get regmap failed\n");
> > +		return PTR_ERR(bbnsm->regmap);
> > +	}
> > +
> > +	bbnsm->irq = platform_get_irq(pdev, 0);
> > +	if (bbnsm->irq < 0)
> > +		return bbnsm->irq;
> > +
> > +	platform_set_drvdata(pdev, bbnsm);
> > +
> > +	/* clear all the pending events */
> > +	regmap_write(bbnsm->regmap, BBNSM_EVENTS, 0x7A);
> > +
> > +	/* Enable the Real-Time counter */
> > +	regmap_update_bits(bbnsm->regmap, BBNSM_CTRL, RTC_EN_MSK,
> RTC_EN);
> > +
> 
> Please don't do that, this removes an important piece of information.
> Instead, let .set_time enable it and check it in .read_time as if this is not set,
> you now you are out of PoR and the time is invalid
> 

Will remove it. set_time has the enable operation. I will add enable check in read_time callback.

> > +	device_init_wakeup(&pdev->dev, true);
> > +	ret = dev_pm_set_wake_irq(&pdev->dev, bbnsm->irq);
> > +	if (ret)
> > +		dev_err(&pdev->dev, "Failed to enable the irq wakeup\n");
> 
> dev_err but the function is not failing. Maybe just dev_warn? Also, is this
> message really necessary?
> 

Not too necessary, I can drop the above log print.

BR

> > +
> > +	ret = devm_request_irq(&pdev->dev, bbnsm->irq,
> bbnsm_rtc_irq_handler,
> > +			IRQF_SHARED, "rtc alarm", &pdev->dev);
> > +	if (ret) {
> > +		dev_err(&pdev->dev, "failed to request irq %d: %d\n",
> > +			bbnsm->irq, ret);
> > +		return ret;
> > +	}
> > +
> > +	bbnsm->rtc->ops = &bbnsm_rtc_ops;
> > +	bbnsm->rtc->range_max = U32_MAX;
> > +
> > +	return devm_rtc_register_device(bbnsm->rtc);
> > +}
> > +
> > +static const struct of_device_id bbnsm_dt_ids[] = {
> > +	{ .compatible = "nxp,bbnsm-rtc", },
> > +	{ /* sentinel */ },
> > +};
> > +MODULE_DEVICE_TABLE(of, bbnsm_dt_ids);
> > +
> > +static struct platform_driver bbnsm_rtc_driver = {
> > +	.driver = {
> > +		.name = "bbnsm_rtc",
> > +		.of_match_table = bbnsm_dt_ids,
> > +	},
> > +	.probe = bbnsm_rtc_probe,
> > +};
> > +module_platform_driver(bbnsm_rtc_driver);
> > +
> > +MODULE_AUTHOR("Jacky Bai <ping.bai at nxp.com>");
> > +MODULE_DESCRIPTION("NXP BBNSM RTC Driver");
> MODULE_LICENSE("GPL");
> > --
> > 2.37.1
> >
> 
> --