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SubjectRe: [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@gmail.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@gmail.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@gmail.com>");
> +MODULE_DESCRIPTION("VIA VT8500 SoC Realtime Clock Driver (RTC)");
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS("platform:vt8500-rtc");

- Lars


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