Message-ID: <4CDE810F.2040400@metafoo.de>
Date:	Sat, 13 Nov 2010 13:14:07 +0100
From:	Lars-Peter Clausen <lars@...afoo.de>
To:	Alexey Charkov <alchark@...il.com>
CC:	linux-arm-kernel@...ts.infradead.org,
	vt8500-wm8505-linux-kernel@...glegroups.com,
	Alessandro Zummo <a.zummo@...ertech.it>,
	linux-kernel@...r.kernel.org, rtc-linux@...glegroups.com
Subject: Re: [PATCH 5/6 v2] rtc: Add support for the RTC in VIA VT8500 and
 compatibles

Alexey Charkov wrote:
> This adds a driver for the RTC devices in VIA and WonderMedia
> Systems-on-Chip. Alarm, 1Hz interrupts, reading and setting time
> are supported.
> 
> Signed-off-by: Alexey Charkov <alchark@...il.com>
> ---
> 
> Please review and (if appropriate) commit to a relevant git tree for
> further integration in 2.6.38.
> 
> Compared to the previous submission, this code just contains a rebase
> against the latest changes introduced in 2.6.37 merge window.
> 
> Relevant platform definitions are introduced by PATCH 1/6 in this series,
> so one would need that to make use of this code.
> 
> Due credits go to the community for providing feedback, advice and
> testing.
> 
>  drivers/rtc/Kconfig      |    7 +
>  drivers/rtc/Makefile     |    1 +
>  drivers/rtc/rtc-vt8500.c |  363 ++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 371 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/rtc/rtc-vt8500.c
> 
> diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
> index 2883428..27ed129 100644
> --- a/drivers/rtc/Kconfig
> +++ b/drivers/rtc/Kconfig
> @@ -865,6 +865,13 @@ config RTC_DRV_PXA
>           This RTC driver uses PXA RTC registers available since pxa27x
>           series (RDxR, RYxR) instead of legacy RCNR, RTAR.
>  
> +config RTC_DRV_VT8500
> +	tristate "VIA/WonderMedia 85xx SoC RTC"
> +	depends on ARCH_VT8500
> +	help
> +	  If you say Y here you will get access to the real time clock
> +	  built into your VIA VT8500 SoC or its relatives.
> +
>  
>  config RTC_DRV_SUN4V
>  	bool "SUN4V Hypervisor RTC"
> diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
> index 4c2832d..1a354e1 100644
> --- a/drivers/rtc/Makefile
> +++ b/drivers/rtc/Makefile
> @@ -97,6 +97,7 @@ obj-$(CONFIG_RTC_DRV_TWL4030)	+= rtc-twl.o
>  obj-$(CONFIG_RTC_DRV_TX4939)	+= rtc-tx4939.o
>  obj-$(CONFIG_RTC_DRV_V3020)	+= rtc-v3020.o
>  obj-$(CONFIG_RTC_DRV_VR41XX)	+= rtc-vr41xx.o
> +obj-$(CONFIG_RTC_DRV_VT8500)	+= rtc-vt8500.o
>  obj-$(CONFIG_RTC_DRV_WM831X)	+= rtc-wm831x.o
>  obj-$(CONFIG_RTC_DRV_WM8350)	+= rtc-wm8350.o
>  obj-$(CONFIG_RTC_DRV_X1205)	+= rtc-x1205.o
> diff --git a/drivers/rtc/rtc-vt8500.c b/drivers/rtc/rtc-vt8500.c
> new file mode 100644
> index 0000000..7260c95
> --- /dev/null
> +++ b/drivers/rtc/rtc-vt8500.c
> @@ -0,0 +1,363 @@
> +/*
> + * drivers/rtc/rtc-vt8500.c
> + *
> + *  Copyright (C) 2010 Alexey Charkov <alchark@...il.com>
> + *
> + * Based on rtc-pxa.c
> + *
> + * This software is licensed under the terms of the GNU General Public
> + * License version 2, as published by the Free Software Foundation, and
> + * may be copied, distributed, and modified under those terms.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/module.h>
> +#include <linux/rtc.h>
> +#include <linux/init.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/bcd.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +
> +/*
> + * Register definitions
> + */
> +#define VT8500_RTC_TS		0x00	/* Time set */
> +#define VT8500_RTC_DS		0x04	/* Date set */
> +#define VT8500_RTC_AS		0x08	/* Alarm set */
> +#define VT8500_RTC_CR		0x0c	/* Control */
> +#define VT8500_RTC_TR		0x10	/* Time read */
> +#define VT8500_RTC_DR		0x14	/* Date read */
> +#define VT8500_RTC_WS		0x18	/* Write status */
> +#define VT8500_RTC_CL		0x20	/* Calibration */
> +#define VT8500_RTC_IS		0x24	/* Interrupt status */
> +#define VT8500_RTC_ST		0x28	/* Status */
> +
> +#define INVALID_TIME_BIT	(1 << 31)
> +
> +#define DATE_CENTURY_S		19
> +#define DATE_YEAR_S		11
> +#define DATE_YEAR_MASK		(0xff << DATE_YEAR_S)
> +#define DATE_MONTH_S		6
> +#define DATE_MONTH_MASK		(0x1f << DATE_MONTH_S)
> +#define DATE_DAY_MASK		0x3f
> +
> +#define TIME_DOW_S		20
> +#define TIME_DOW_MASK		(0x07 << TIME_DOW_S)
> +#define TIME_HOUR_S		14
> +#define TIME_HOUR_MASK		(0x3f << TIME_HOUR_S)
> +#define TIME_MIN_S		7
> +#define TIME_MIN_MASK		(0x7f << TIME_MIN_S)
> +#define TIME_SEC_MASK		0x7f
> +
> +#define ALARM_DAY_S		20
> +#define ALARM_DAY_MASK		(0x3f << ALARM_DAY_S)
> +
> +#define ALARM_DAY_BIT		(1 << 29)
> +#define ALARM_HOUR_BIT		(1 << 28)
> +#define ALARM_MIN_BIT		(1 << 27)
> +#define ALARM_SEC_BIT		(1 << 26)
> +
> +#define ALARM_ENABLE_MASK	(ALARM_DAY_BIT \
> +				| ALARM_HOUR_BIT \
> +				| ALARM_MIN_BIT \
> +				| ALARM_SEC_BIT)
> +
> +struct vt8500_rtc {
> +	void __iomem		*regbase;
> +	int			irq_alarm;
> +	int			irq_hz;
> +	struct rtc_device	*rtc;
> +	spinlock_t		lock;		/* Protects this structure */
> +	struct rtc_time		rtc_alarm;
This field is unused.
> +};
> +
> +static irqreturn_t vt8500_rtc_irq(int irq, void *dev_id)
> +{
> +	struct platform_device *pdev = to_platform_device(dev_id);
> +	struct vt8500_rtc *vt8500_rtc = platform_get_drvdata(pdev);
Wouldn't it be better to pass the vt8500_rtc struct as dev_id to request_irq?

> +	u32 isr;
> +	unsigned long events = 0;
> +
> +	spin_lock(&vt8500_rtc->lock);
> +
> +	/* clear interrupt sources */
> +	isr = readl(vt8500_rtc->regbase + VT8500_RTC_IS);
> +	writel(isr, vt8500_rtc->regbase + VT8500_RTC_IS);
You only have to hold the lock until here.

> +
> +	if (isr & 1)
> +		events |= RTC_AF | RTC_IRQF;
> +
> +	/* Only second/minute interrupts are supported */
> +	if (isr & 2)
> +		events |= RTC_UF | RTC_IRQF;
> +
> +	rtc_update_irq(vt8500_rtc->rtc, 1, events);
> +
> +	spin_unlock(&vt8500_rtc->lock);
> +	return IRQ_HANDLED;
> +}
> +
> +static int vt8500_rtc_open(struct device *dev)
> +{
> +	struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);
> +	int ret;
> +
> +	ret = request_irq(vt8500_rtc->irq_hz, vt8500_rtc_irq, IRQF_DISABLED,
> +			  "rtc 1Hz", dev);
IRQF_DISABLED is deprecapted and a NOOP right now. You shouldn't add new code using it.
> +	if (ret < 0) {
> +		dev_err(dev, "can't get irq %i, err %d\n", vt8500_rtc->irq_hz,
> +			ret);
> +		goto err_irq_hz;
> +	}
> +	ret = request_irq(vt8500_rtc->irq_alarm, vt8500_rtc_irq, IRQF_DISABLED,
> +			  "rtc alarm", dev);
> +	if (ret < 0) {
> +		dev_err(dev, "can't get irq %i, err %d\n",
> +			vt8500_rtc->irq_alarm, ret);
> +		goto err_irq_alarm;
> +	}
> +	return 0;

Is there any specific reason why you don't keep the irq requested for the lifetime of
the device?
You wont be able to provide wakeup functionallity this way.

> +
> +err_irq_alarm:
> +	free_irq(vt8500_rtc->irq_hz, dev);
> +err_irq_hz:
> +	return ret;
> +}
> +
> +static void vt8500_rtc_release(struct device *dev)
> +{
> +	struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);
> +
> +	spin_lock_irq(&vt8500_rtc->lock);
> +	/* Disable alarm matching */
> +	writel(0, vt8500_rtc->regbase + VT8500_RTC_IS);
> +	spin_unlock_irq(&vt8500_rtc->lock);
> +
> +	free_irq(vt8500_rtc->irq_alarm, dev);
> +	free_irq(vt8500_rtc->irq_hz, dev);
> +}
> +
> +static int vt8500_rtc_read_time(struct device *dev, struct rtc_time *tm)
> +{
> +	struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);
> +	u32 date, time;
> +
> +	date = readl(vt8500_rtc->regbase + VT8500_RTC_DR);
> +	time = readl(vt8500_rtc->regbase + VT8500_RTC_TR);
> +
> +	tm->tm_sec = bcd2bin(time & TIME_SEC_MASK);
> +	tm->tm_min = bcd2bin((time & TIME_MIN_MASK) >> TIME_MIN_S);
> +	tm->tm_hour = bcd2bin((time & TIME_HOUR_MASK) >> TIME_HOUR_S);
> +	tm->tm_mday = bcd2bin(date & DATE_DAY_MASK);
> +	tm->tm_mon = bcd2bin((date & DATE_MONTH_MASK) >> DATE_MONTH_S);
> +	tm->tm_year = bcd2bin((date & DATE_YEAR_MASK) >> DATE_YEAR_S);
> +	tm->tm_wday = (time & TIME_DOW_MASK) >> TIME_DOW_S;
> +
> +	return 0;
return rtc_valid_tm(tm);

> +}
> +
> +static int vt8500_rtc_set_time(struct device *dev, struct rtc_time *tm)
> +{
> +	struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);
> +
> +	writel((bin2bcd(tm->tm_year) << DATE_YEAR_S)
> +		| (bin2bcd(tm->tm_mon) << DATE_MONTH_S)
> +		| (bin2bcd(tm->tm_mday)),
> +		vt8500_rtc->regbase + VT8500_RTC_DS);
> +	writel((bin2bcd(tm->tm_wday) << TIME_DOW_S)
> +		| (bin2bcd(tm->tm_hour) << TIME_HOUR_S)
> +		| (bin2bcd(tm->tm_min) << TIME_MIN_S)
> +		| (bin2bcd(tm->tm_sec)),
> +		vt8500_rtc->regbase + VT8500_RTC_TS);
> +
> +	return 0;
> +}
> +
> +static int vt8500_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
> +{
> +	struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);
> +	u32 isr, alarm;
> +
> +	alarm = readl(vt8500_rtc->regbase + VT8500_RTC_AS);
> +	isr = readl(vt8500_rtc->regbase + VT8500_RTC_IS);
> +
> +	alrm->time.tm_mday = bcd2bin((alarm & ALARM_DAY_MASK) >> ALARM_DAY_S);
> +	alrm->time.tm_hour = bcd2bin((alarm & TIME_HOUR_MASK) >> TIME_HOUR_S);
> +	alrm->time.tm_min = bcd2bin((alarm & TIME_MIN_MASK) >> TIME_MIN_S);
> +	alrm->time.tm_sec = bcd2bin((alarm & TIME_SEC_MASK));
> +
> +	alrm->enabled = (alarm & ALARM_ENABLE_MASK) ? 1 : 0;
> +
> +	alrm->pending = (isr & 1) ? 1 : 0;
> +	return 0;
return rtc_valid_tm(&alrm->time);

> +}
> +
> +static int vt8500_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
> +{
> +	struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);
> +
> +	writel((alrm->enabled ? ALARM_ENABLE_MASK : 0)
> +		| (bin2bcd(alrm->time.tm_mday) << ALARM_DAY_S)
> +		| (bin2bcd(alrm->time.tm_hour) << TIME_HOUR_S)
> +		| (bin2bcd(alrm->time.tm_min) << TIME_MIN_S)
> +		| (bin2bcd(alrm->time.tm_sec)),
> +		vt8500_rtc->regbase + VT8500_RTC_AS);
> +
> +	return 0;
> +}
> +
> +static int vt8500_rtc_ioctl(struct device *dev, unsigned int cmd,
> +		unsigned long arg)
> +{
> +	struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);
> +	int ret = 0;
> +	unsigned long tmp;
> +
> +	spin_lock_irq(&vt8500_rtc->lock);
> +	switch (cmd) {
> +	case RTC_AIE_OFF:
> +		tmp = readl(vt8500_rtc->regbase + VT8500_RTC_AS);
> +		writel(tmp & ~ALARM_ENABLE_MASK,
> +		       vt8500_rtc->regbase + VT8500_RTC_AS);
> +		break;
> +	case RTC_AIE_ON:
> +		tmp = readl(vt8500_rtc->regbase + VT8500_RTC_AS);
> +		writel(tmp | ALARM_ENABLE_MASK,
> +		       vt8500_rtc->regbase + VT8500_RTC_AS);
> +		break;
> +	case RTC_UIE_OFF:
> +		tmp = readl(vt8500_rtc->regbase + VT8500_RTC_CR);
> +		writel(tmp & ~(1 << 2),
> +		       vt8500_rtc->regbase + VT8500_RTC_CR);
It would be better if you added descriptive defines for the bits of the CR register.
Makes reading the driver easier.
> +		break;
> +	case RTC_UIE_ON:
> +		tmp = readl(vt8500_rtc->regbase + VT8500_RTC_CR);
> +		writel(tmp | ((1 << 3) | (1 << 2)),
> +		       vt8500_rtc->regbase + VT8500_RTC_CR);
> +		break;
> +	default:
> +		ret = -ENOIOCTLCMD;

You should rather implement these by providing the update_irq_enable and
alarm_irq_enable callbacks of your rtc_class_ops instead of handling the ioctls yourself.

> +	}
> +
> +	spin_unlock_irq(&vt8500_rtc->lock);
> +	return ret;
> +}
> +
> +static const struct rtc_class_ops vt8500_rtc_ops = {
> +	.open = vt8500_rtc_open,
> +	.release = vt8500_rtc_release,
> +	.ioctl = vt8500_rtc_ioctl,
> +	.read_time = vt8500_rtc_read_time,
> +	.set_time = vt8500_rtc_set_time,
> +	.read_alarm = vt8500_rtc_read_alarm,
> +	.set_alarm = vt8500_rtc_set_alarm,
> +};
> +
> +static int __init vt8500_rtc_probe(struct platform_device *pdev)
__devinit
> +{
> +	struct device *dev = &pdev->dev;
> +	struct vt8500_rtc *vt8500_rtc;
> +	struct resource *res;
> +	int ret;
> +
> +	vt8500_rtc = kzalloc(sizeof(struct vt8500_rtc), GFP_KERNEL);
> +	if (!vt8500_rtc)
> +		return -ENOMEM;
> +
> +	spin_lock_init(&vt8500_rtc->lock);
> +	platform_set_drvdata(pdev, vt8500_rtc);
> +
> +	ret = -ENXIO;
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!res) {
> +		dev_err(dev, "No I/O memory resource defined\n");
> +		goto err_map;
> +	}
> +
> +	vt8500_rtc->irq_alarm = platform_get_irq(pdev, 0);
> +	if (vt8500_rtc->irq_alarm < 0) {
> +		dev_err(dev, "No alarm IRQ resource defined\n");
> +		goto err_map;
> +	}
> +
> +	vt8500_rtc->irq_hz = platform_get_irq(pdev, 1);
> +	if (vt8500_rtc->irq_hz < 0) {
> +		dev_err(dev, "No 1Hz IRQ resource defined\n");
> +		goto err_map;
> +	}

You should first request the memory region before ioremapping it

> +
> +	ret = -ENOMEM;
Move the assignment inside the if statement.
> +	vt8500_rtc->regbase = ioremap(res->start, resource_size(res));
> +	if (!vt8500_rtc->regbase) {
> +		dev_err(&pdev->dev, "Unable to map RTC I/O memory\n");
> +		goto err_map;
> +	}
> +
> +	/* Enable the second/minute interrupt generation and enable RTC */
> +	writel((1 << 3) | (1 << 2) | 1, vt8500_rtc->regbase + VT8500_RTC_CR);
> +
> +	vt8500_rtc->rtc = rtc_device_register("vt8500-rtc", &pdev->dev,
> +					      &vt8500_rtc_ops, THIS_MODULE);
> +	ret = PTR_ERR(vt8500_rtc->rtc);
Move the assignment inside the if statement.
> +	if (IS_ERR(vt8500_rtc->rtc)) {
> +		dev_err(dev, "Failed to register RTC device -> %d\n", ret);
> +		goto err_rtc_reg;
> +	}
> +
> +	device_init_wakeup(dev, 1);
As far as I can see your driver does not provide any wakeup functionality.
> +
> +	return 0;
> +
> +err_rtc_reg:
> +	iounmap(vt8500_rtc->regbase);
> +err_map:
> +	kfree(vt8500_rtc);
> +	return ret;
> +}
> +
> +static int __exit vt8500_rtc_remove(struct platform_device *pdev)
__devexit
> +{
> +	struct vt8500_rtc *vt8500_rtc = platform_get_drvdata(pdev);
> +
> +	rtc_device_unregister(vt8500_rtc->rtc);
> +
> +	spin_lock_irq(&vt8500_rtc->lock);
> +	iounmap(vt8500_rtc->regbase);
> +	spin_unlock_irq(&vt8500_rtc->lock);
> +
> +	kfree(vt8500_rtc);
> +
> +	return 0;
> +}
> +
> +static struct platform_driver vt8500_rtc_driver = {
> +	.probe		= vt8500_rtc_probe,
> +	.remove		= __exit_p(vt8500_rtc_remove),
__devexit_p
> +	.driver		= {
> +		.name	= "vt8500-rtc"
.owner = THIS_MODULE,
> +	},
> +};
> +
> +static int __init vt8500_rtc_init(void)
> +{
> +	return platform_driver_register(&vt8500_rtc_driver);
> +}
> +
> +static void __exit vt8500_rtc_exit(void)
> +{
> +	platform_driver_unregister(&vt8500_rtc_driver);
> +}
> +
> +module_init(vt8500_rtc_init);
> +module_exit(vt8500_rtc_exit);
module_{init,exit} should go right beneath the function they reference.
> +
> +MODULE_AUTHOR("Alexey Charkov <alchark@...il.com>");
> +MODULE_DESCRIPTION("VIA VT8500 SoC Realtime Clock Driver (RTC)");
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS("platform:vt8500-rtc");

- Lars
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