Patchwork [v3] RTC: Add JZ4740 RTC driver

login
register
mail settings
Submitter Lars-Peter Clausen
Date June 19, 2010, 7:29 p.m.
Message ID <1276975790-25623-1-git-send-email-lars@metafoo.de>
Download mbox | patch
Permalink /patch/56247/
State New
Headers show

Comments

Lars-Peter Clausen - June 19, 2010, 7:29 p.m.
This patch adds support for the RTC unit on JZ4740 SoCs.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Paul Gortmaker <p_gortmaker@yahoo.com>
Cc: rtc-linux@googlegroups.com

--
Changes since v1
- Use dev_get_drvdata directly instead of wrapping it in dev_to_rtc
- Add common implementation for jz4740_rtc_{alarm,update}_irq_enable
- Check whether rtc structure could be allocated
- Remove deadlocks which could occur if the HW was broken

Changes since v2
- Use kzalloc instead of kmalloc
- Propagate errors in jz4740_rtc_reg_write up to its callers
---
 drivers/rtc/Kconfig      |   11 ++
 drivers/rtc/Makefile     |    1 +
 drivers/rtc/rtc-jz4740.c |  345 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 357 insertions(+), 0 deletions(-)
 create mode 100644 drivers/rtc/rtc-jz4740.c
Wan ZongShun - June 20, 2010, 1:13 a.m.
> This patch adds support for the RTC unit on JZ4740 SoCs.
> 
> Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
> Cc: Alessandro Zummo <a.zummo@towertech.it>
> Cc: Paul Gortmaker <p_gortmaker@yahoo.com>
> Cc: rtc-linux@googlegroups.com
> 
> --
> Changes since v1
> - Use dev_get_drvdata directly instead of wrapping it in dev_to_rtc
> - Add common implementation for jz4740_rtc_{alarm,update}_irq_enable
> - Check whether rtc structure could be allocated
> - Remove deadlocks which could occur if the HW was broken
> 
> Changes since v2
> - Use kzalloc instead of kmalloc
> - Propagate errors in jz4740_rtc_reg_write up to its callers

Acked-by: Wan ZongShun <mcuos.com@gmail.com>

Andrew, the v3 patch has fixed some above issues, it looks good to me now.
Could you please consider merging it to your git tree?

Thanks!

> ---
>  drivers/rtc/Kconfig      |   11 ++
>  drivers/rtc/Makefile     |    1 +
>  drivers/rtc/rtc-jz4740.c |  345 ++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 357 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/rtc/rtc-jz4740.c
> 
> diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
> index 10ba12c..d0ed7e6 100644
> --- a/drivers/rtc/Kconfig
> +++ b/drivers/rtc/Kconfig
> @@ -905,4 +905,15 @@ config RTC_DRV_MPC5121
>  	  This driver can also be built as a module. If so, the module
>  	  will be called rtc-mpc5121.
>  
> +config RTC_DRV_JZ4740
> +	tristate "Ingenic JZ4740 SoC"
> +	depends on RTC_CLASS
> +	depends on MACH_JZ4740
> +	help
> +	  If you say yes here you get support for the Ingenic JZ4740 SoC RTC
> +	  controller.
> +
> +	  This driver can also be buillt as a module. If so, the module
> +	  will be called rtc-jz4740.
> +
>  endif # RTC_CLASS
> diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
> index 5adbba7..fedf9bb 100644
> --- a/drivers/rtc/Makefile
> +++ b/drivers/rtc/Makefile
> @@ -47,6 +47,7 @@ obj-$(CONFIG_RTC_DRV_EP93XX)	+= rtc-ep93xx.o
>  obj-$(CONFIG_RTC_DRV_FM3130)	+= rtc-fm3130.o
>  obj-$(CONFIG_RTC_DRV_GENERIC)	+= rtc-generic.o
>  obj-$(CONFIG_RTC_DRV_ISL1208)	+= rtc-isl1208.o
> +obj-$(CONFIG_RTC_DRV_JZ4740)	+= rtc-jz4740.o
>  obj-$(CONFIG_RTC_DRV_M41T80)	+= rtc-m41t80.o
>  obj-$(CONFIG_RTC_DRV_M41T94)	+= rtc-m41t94.o
>  obj-$(CONFIG_RTC_DRV_M48T35)	+= rtc-m48t35.o
> diff --git a/drivers/rtc/rtc-jz4740.c b/drivers/rtc/rtc-jz4740.c
> new file mode 100644
> index 0000000..10b59fc
> --- /dev/null
> +++ b/drivers/rtc/rtc-jz4740.c
> @@ -0,0 +1,345 @@
> +/*
> + *  Copyright (C) 2009-2010, Lars-Peter Clausen <lars@metafoo.de>
> + *	 JZ4740 SoC RTC driver
> + *
> + *  This program is free software; you can redistribute it and/or modify it
> + *  under  the terms of  the GNU General Public License as published by the
> + *  Free Software Foundation;  either version 2 of the License, or (at your
> + *  option) any later version.
> + *
> + *  You should have received a copy of the GNU General Public License along
> + *  with this program; if not, write to the Free Software Foundation, Inc.,
> + *  675 Mass Ave, Cambridge, MA 02139, USA.
> + *
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/rtc.h>
> +#include <linux/slab.h>
> +#include <linux/spinlock.h>
> +
> +#define JZ_REG_RTC_CTRL		0x00
> +#define JZ_REG_RTC_SEC		0x04
> +#define JZ_REG_RTC_SEC_ALARM	0x08
> +#define JZ_REG_RTC_REGULATOR	0x0C
> +#define JZ_REG_RTC_HIBERNATE	0x20
> +#define JZ_REG_RTC_SCRATCHPAD	0x34
> +
> +#define JZ_RTC_CTRL_WRDY	BIT(7)
> +#define JZ_RTC_CTRL_1HZ		BIT(6)
> +#define JZ_RTC_CTRL_1HZ_IRQ	BIT(5)
> +#define JZ_RTC_CTRL_AF		BIT(4)
> +#define JZ_RTC_CTRL_AF_IRQ	BIT(3)
> +#define JZ_RTC_CTRL_AE		BIT(2)
> +#define JZ_RTC_CTRL_ENABLE	BIT(0)
> +
> +struct jz4740_rtc {
> +	struct resource *mem;
> +	void __iomem *base;
> +
> +	struct rtc_device *rtc;
> +
> +	unsigned int irq;
> +
> +	spinlock_t lock;
> +};
> +
> +static inline uint32_t jz4740_rtc_reg_read(struct jz4740_rtc *rtc, size_t reg)
> +{
> +	return readl(rtc->base + reg);
> +}
> +
> +static int jz4740_rtc_wait_write_ready(struct jz4740_rtc *rtc)
> +{
> +	uint32_t ctrl;
> +	int timeout = 1000;
> +
> +	do {
> +		ctrl = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_CTRL);
> +	} while (!(ctrl & JZ_RTC_CTRL_WRDY) && --timeout);
> +
> +	return timeout ? 0 : -EIO;
> +}
> +
> +static inline int jz4740_rtc_reg_write(struct jz4740_rtc *rtc, size_t reg,
> +	uint32_t val)
> +{
> +	int ret;
> +	ret = jz4740_rtc_wait_write_ready(rtc);
> +	if (ret == 0)
> +		writel(val, rtc->base + reg);
> +
> +	return ret;
> +}
> +
> +static int jz4740_rtc_ctrl_set_bits(struct jz4740_rtc *rtc, uint32_t mask,
> +	bool set)
> +{
> +	int ret;
> +	unsigned long flags;
> +	uint32_t ctrl;
> +
> +	spin_lock_irqsave(&rtc->lock, flags);
> +
> +	ctrl = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_CTRL);
> +
> +	/* Don't clear interrupt flags by accident */
> +	ctrl |= JZ_RTC_CTRL_1HZ | JZ_RTC_CTRL_AF;
> +
> +	if (set)
> +		ctrl |= mask;
> +	else
> +		ctrl &= ~mask;
> +
> +	ret = jz4740_rtc_reg_write(rtc, JZ_REG_RTC_CTRL, ctrl);
> +
> +	spin_unlock_irqrestore(&rtc->lock, flags);
> +
> +	return ret;
> +}
> +
> +static int jz4740_rtc_read_time(struct device *dev, struct rtc_time *time)
> +{
> +	struct jz4740_rtc *rtc = dev_get_drvdata(dev);
> +	uint32_t secs, secs2;
> +	int timeout = 5;
> +
> +	/* If the seconds register is read while it is updated, it can contain a
> +	 * bogus value. This can be avoided by making sure that two consecutive
> +	 * reads have the same value.
> +	 */
> +	secs = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_SEC);
> +	secs2 = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_SEC);
> +
> +	while (secs != secs2 && --timeout) {
> +		secs = secs2;
> +		secs2 = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_SEC);
> +	}
> +
> +	if (timeout == 0)
> +		return -EIO;
> +
> +	rtc_time_to_tm(secs, time);
> +
> +	return rtc_valid_tm(time);
> +}
> +
> +static int jz4740_rtc_set_mmss(struct device *dev, unsigned long secs)
> +{
> +	struct jz4740_rtc *rtc = dev_get_drvdata(dev);
> +
> +	return jz4740_rtc_reg_write(rtc, JZ_REG_RTC_SEC, secs);
> +}
> +
> +static int jz4740_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
> +{
> +	struct jz4740_rtc *rtc = dev_get_drvdata(dev);
> +	uint32_t secs;
> +	uint32_t ctrl;
> +
> +	secs = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_SEC_ALARM);
> +
> +	ctrl = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_CTRL);
> +
> +	alrm->enabled = !!(ctrl & JZ_RTC_CTRL_AE);
> +	alrm->pending = !!(ctrl & JZ_RTC_CTRL_AF);
> +
> +	rtc_time_to_tm(secs, &alrm->time);
> +
> +	return rtc_valid_tm(&alrm->time);
> +}
> +
> +static int jz4740_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
> +{
> +	int ret;
> +	struct jz4740_rtc *rtc = dev_get_drvdata(dev);
> +	unsigned long secs;
> +
> +	rtc_tm_to_time(&alrm->time, &secs);
> +
> +	ret = jz4740_rtc_reg_write(rtc, JZ_REG_RTC_SEC_ALARM, secs);
> +	if (!ret)
> +		ret = jz4740_rtc_ctrl_set_bits(rtc, JZ_RTC_CTRL_AE, alrm->enabled);
> +
> +	return ret;
> +}
> +
> +static int jz4740_rtc_update_irq_enable(struct device *dev, unsigned int enable)
> +{
> +	struct jz4740_rtc *rtc = dev_get_drvdata(dev);
> +	return jz4740_rtc_ctrl_set_bits(rtc, JZ_RTC_CTRL_1HZ_IRQ, enable);
> +}
> +
> +static int jz4740_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
> +{
> +	struct jz4740_rtc *rtc = dev_get_drvdata(dev);
> +	return jz4740_rtc_ctrl_set_bits(rtc, JZ_RTC_CTRL_AF_IRQ, enable);
> +}
> +
> +static struct rtc_class_ops jz4740_rtc_ops = {
> +	.read_time	= jz4740_rtc_read_time,
> +	.set_mmss	= jz4740_rtc_set_mmss,
> +	.read_alarm	= jz4740_rtc_read_alarm,
> +	.set_alarm	= jz4740_rtc_set_alarm,
> +	.update_irq_enable = jz4740_rtc_update_irq_enable,
> +	.alarm_irq_enable = jz4740_rtc_alarm_irq_enable,
> +};
> +
> +static irqreturn_t jz4740_rtc_irq(int irq, void *data)
> +{
> +	struct jz4740_rtc *rtc = data;
> +	uint32_t ctrl;
> +	unsigned long events = 0;
> +
> +	ctrl = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_CTRL);
> +
> +	if (ctrl & JZ_RTC_CTRL_1HZ)
> +		events |= (RTC_UF | RTC_IRQF);
> +
> +	if (ctrl & JZ_RTC_CTRL_AF)
> +		events |= (RTC_AF | RTC_IRQF);
> +
> +	rtc_update_irq(rtc->rtc, 1, events);
> +
> +	jz4740_rtc_ctrl_set_bits(rtc, JZ_RTC_CTRL_1HZ | JZ_RTC_CTRL_AF, false);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +void jz4740_rtc_poweroff(struct device *dev)
> +{
> +	struct jz4740_rtc *rtc = dev_get_drvdata(dev);
> +	jz4740_rtc_reg_write(rtc, JZ_REG_RTC_HIBERNATE, 1);
> +}
> +EXPORT_SYMBOL_GPL(jz4740_rtc_poweroff);
> +
> +static int __devinit jz4740_rtc_probe(struct platform_device *pdev)
> +{
> +	int ret;
> +	struct jz4740_rtc *rtc;
> +	uint32_t scratchpad;
> +
> +	rtc = kzalloc(sizeof(*rtc), GFP_KERNEL);
> +	if (!rtc)
> +		return -ENOMEM;
> +
> +	rtc->irq = platform_get_irq(pdev, 0);
> +	if (rtc->irq < 0) {
> +		ret = -ENOENT;
> +		dev_err(&pdev->dev, "Failed to get platform irq\n");
> +		goto err_free;
> +	}
> +
> +	rtc->mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!rtc->mem) {
> +		ret = -ENOENT;
> +		dev_err(&pdev->dev, "Failed to get platform mmio memory\n");
> +		goto err_free;
> +	}
> +
> +	rtc->mem = request_mem_region(rtc->mem->start, resource_size(rtc->mem),
> +					pdev->name);
> +	if (!rtc->mem) {
> +		ret = -EBUSY;
> +		dev_err(&pdev->dev, "Failed to request mmio memory region\n");
> +		goto err_free;
> +	}
> +
> +	rtc->base = ioremap_nocache(rtc->mem->start, resource_size(rtc->mem));
> +	if (!rtc->base) {
> +		ret = -EBUSY;
> +		dev_err(&pdev->dev, "Failed to ioremap mmio memory\n");
> +		goto err_release_mem_region;
> +	}
> +
> +	spin_lock_init(&rtc->lock);
> +
> +	platform_set_drvdata(pdev, rtc);
> +
> +	rtc->rtc = rtc_device_register(pdev->name, &pdev->dev, &jz4740_rtc_ops,
> +					THIS_MODULE);
> +	if (IS_ERR(rtc->rtc)) {
> +		ret = PTR_ERR(rtc->rtc);
> +		dev_err(&pdev->dev, "Failed to register rtc device: %d\n", ret);
> +		goto err_iounmap;
> +	}
> +
> +	ret = request_irq(rtc->irq, jz4740_rtc_irq, 0,
> +				pdev->name, rtc);
> +	if (ret) {
> +		dev_err(&pdev->dev, "Failed to request rtc irq: %d\n", ret);
> +		goto err_unregister_rtc;
> +	}
> +
> +	scratchpad = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_SCRATCHPAD);
> +	if (scratchpad != 0x12345678) {
> +		ret = jz4740_rtc_reg_write(rtc, JZ_REG_RTC_SCRATCHPAD, 0x12345678);
> +		ret = jz4740_rtc_reg_write(rtc, JZ_REG_RTC_SEC, 0);
> +		if (ret) {
> +			dev_err(&pdev->dev, "Could not write write to RTC registers\n");
> +			goto err_free_irq;
> +		}
> +	}
> +
> +	return 0;
> +
> +err_free_irq:
> +	free_irq(rtc->irq, rtc);
> +err_unregister_rtc:
> +	rtc_device_unregister(rtc->rtc);
> +err_iounmap:
> +	platform_set_drvdata(pdev, NULL);
> +	iounmap(rtc->base);
> +err_release_mem_region:
> +	release_mem_region(rtc->mem->start, resource_size(rtc->mem));
> +err_free:
> +	kfree(rtc);
> +
> +	return ret;
> +}
> +
> +static int __devexit jz4740_rtc_remove(struct platform_device *pdev)
> +{
> +	struct jz4740_rtc *rtc = platform_get_drvdata(pdev);
> +
> +	free_irq(rtc->irq, rtc);
> +
> +	rtc_device_unregister(rtc->rtc);
> +
> +	iounmap(rtc->base);
> +	release_mem_region(rtc->mem->start, resource_size(rtc->mem));
> +
> +	kfree(rtc);
> +
> +	platform_set_drvdata(pdev, NULL);
> +
> +	return 0;
> +}
> +
> +struct platform_driver jz4740_rtc_driver = {
> +	.probe = jz4740_rtc_probe,
> +	.remove = __devexit_p(jz4740_rtc_remove),
> +	.driver = {
> +		.name = "jz4740-rtc",
> +		.owner = THIS_MODULE,
> +	},
> +};
> +
> +static int __init jz4740_rtc_init(void)
> +{
> +	return platform_driver_register(&jz4740_rtc_driver);
> +}
> +module_init(jz4740_rtc_init);
> +
> +static void __exit jz4740_rtc_exit(void)
> +{
> +	platform_driver_unregister(&jz4740_rtc_driver);
> +}
> +module_exit(jz4740_rtc_exit);
> +
> +MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
> +MODULE_LICENSE("GPL");
> +MODULE_DESCRIPTION("RTC driver for the JZ4740 SoC\n");
> +MODULE_ALIAS("platform:jz4740-rtc");
Lars-Peter Clausen - June 20, 2010, 1:23 a.m.
Wan ZongShun wrote:
>
>> This patch adds support for the RTC unit on JZ4740 SoCs.
>>
>> Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
>> Cc: Alessandro Zummo <a.zummo@towertech.it>
>> Cc: Paul Gortmaker <p_gortmaker@yahoo.com>
>> Cc: rtc-linux@googlegroups.com
>>
>> -- 
>> Changes since v1
>> - Use dev_get_drvdata directly instead of wrapping it in dev_to_rtc
>> - Add common implementation for jz4740_rtc_{alarm,update}_irq_enable
>> - Check whether rtc structure could be allocated
>> - Remove deadlocks which could occur if the HW was broken
>>
>> Changes since v2
>> - Use kzalloc instead of kmalloc
>> - Propagate errors in jz4740_rtc_reg_write up to its callers
>
> Acked-by: Wan ZongShun <mcuos.com@gmail.com>
>
> Andrew, the v3 patch has fixed some above issues, it looks good to me
> now.
> Could you please consider merging it to your git tree?
>
Hi

As written in the introduction mail to this thread it would be good if
the majority of the patches could go through Ralfs tree.
So if the patch is good an "Acked-by:" would be preferable.

Thanks,
- Lars
Wan ZongShun - June 20, 2010, 1:30 a.m.
Lars-Peter Clausen :
> Wan ZongShun wrote:
>>> This patch adds support for the RTC unit on JZ4740 SoCs.
>>>
>>> Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
>>> Cc: Alessandro Zummo <a.zummo@towertech.it>
>>> Cc: Paul Gortmaker <p_gortmaker@yahoo.com>
>>> Cc: rtc-linux@googlegroups.com
>>>
>>> -- 
>>> Changes since v1
>>> - Use dev_get_drvdata directly instead of wrapping it in dev_to_rtc
>>> - Add common implementation for jz4740_rtc_{alarm,update}_irq_enable
>>> - Check whether rtc structure could be allocated
>>> - Remove deadlocks which could occur if the HW was broken
>>>
>>> Changes since v2
>>> - Use kzalloc instead of kmalloc
>>> - Propagate errors in jz4740_rtc_reg_write up to its callers
>> Acked-by: Wan ZongShun <mcuos.com@gmail.com>
>>
>> Andrew, the v3 patch has fixed some above issues, it looks good to me
>> now.
>> Could you please consider merging it to your git tree?
>>
> Hi
> 
> As written in the introduction mail to this thread it would be good if
> the majority of the patches could go through Ralfs tree.
> So if the patch is good an "Acked-by:" would be preferable.
> 
Okay, Sound like good to me, please do you want to do.
Acked-by: Wan ZongShun <mcuos.com@gmail.com>

> Thanks,
> - Lars
> 
> 
>
Alessandro Zummo - June 22, 2010, 5:53 a.m.
On Sat, 19 Jun 2010 21:29:50 +0200
Lars-Peter Clausen <lars@metafoo.de> wrote:

> This patch adds support for the RTC unit on JZ4740 SoCs.
> 
> Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
> Cc: Alessandro Zummo <a.zummo@towertech.it>
> Cc: Paul Gortmaker <p_gortmaker@yahoo.com>
> Cc: rtc-linux@googlegroups.com

 Acked-by: Alessandro Zummo <a.zummo@towertech.it>

Patch

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 10ba12c..d0ed7e6 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -905,4 +905,15 @@  config RTC_DRV_MPC5121
 	  This driver can also be built as a module. If so, the module
 	  will be called rtc-mpc5121.
 
+config RTC_DRV_JZ4740
+	tristate "Ingenic JZ4740 SoC"
+	depends on RTC_CLASS
+	depends on MACH_JZ4740
+	help
+	  If you say yes here you get support for the Ingenic JZ4740 SoC RTC
+	  controller.
+
+	  This driver can also be buillt as a module. If so, the module
+	  will be called rtc-jz4740.
+
 endif # RTC_CLASS
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 5adbba7..fedf9bb 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -47,6 +47,7 @@  obj-$(CONFIG_RTC_DRV_EP93XX)	+= rtc-ep93xx.o
 obj-$(CONFIG_RTC_DRV_FM3130)	+= rtc-fm3130.o
 obj-$(CONFIG_RTC_DRV_GENERIC)	+= rtc-generic.o
 obj-$(CONFIG_RTC_DRV_ISL1208)	+= rtc-isl1208.o
+obj-$(CONFIG_RTC_DRV_JZ4740)	+= rtc-jz4740.o
 obj-$(CONFIG_RTC_DRV_M41T80)	+= rtc-m41t80.o
 obj-$(CONFIG_RTC_DRV_M41T94)	+= rtc-m41t94.o
 obj-$(CONFIG_RTC_DRV_M48T35)	+= rtc-m48t35.o
diff --git a/drivers/rtc/rtc-jz4740.c b/drivers/rtc/rtc-jz4740.c
new file mode 100644
index 0000000..10b59fc
--- /dev/null
+++ b/drivers/rtc/rtc-jz4740.c
@@ -0,0 +1,345 @@ 
+/*
+ *  Copyright (C) 2009-2010, Lars-Peter Clausen <lars@metafoo.de>
+ *	 JZ4740 SoC RTC driver
+ *
+ *  This program is free software; you can redistribute it and/or modify it
+ *  under  the terms of  the GNU General Public License as published by the
+ *  Free Software Foundation;  either version 2 of the License, or (at your
+ *  option) any later version.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+
+#define JZ_REG_RTC_CTRL		0x00
+#define JZ_REG_RTC_SEC		0x04
+#define JZ_REG_RTC_SEC_ALARM	0x08
+#define JZ_REG_RTC_REGULATOR	0x0C
+#define JZ_REG_RTC_HIBERNATE	0x20
+#define JZ_REG_RTC_SCRATCHPAD	0x34
+
+#define JZ_RTC_CTRL_WRDY	BIT(7)
+#define JZ_RTC_CTRL_1HZ		BIT(6)
+#define JZ_RTC_CTRL_1HZ_IRQ	BIT(5)
+#define JZ_RTC_CTRL_AF		BIT(4)
+#define JZ_RTC_CTRL_AF_IRQ	BIT(3)
+#define JZ_RTC_CTRL_AE		BIT(2)
+#define JZ_RTC_CTRL_ENABLE	BIT(0)
+
+struct jz4740_rtc {
+	struct resource *mem;
+	void __iomem *base;
+
+	struct rtc_device *rtc;
+
+	unsigned int irq;
+
+	spinlock_t lock;
+};
+
+static inline uint32_t jz4740_rtc_reg_read(struct jz4740_rtc *rtc, size_t reg)
+{
+	return readl(rtc->base + reg);
+}
+
+static int jz4740_rtc_wait_write_ready(struct jz4740_rtc *rtc)
+{
+	uint32_t ctrl;
+	int timeout = 1000;
+
+	do {
+		ctrl = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_CTRL);
+	} while (!(ctrl & JZ_RTC_CTRL_WRDY) && --timeout);
+
+	return timeout ? 0 : -EIO;
+}
+
+static inline int jz4740_rtc_reg_write(struct jz4740_rtc *rtc, size_t reg,
+	uint32_t val)
+{
+	int ret;
+	ret = jz4740_rtc_wait_write_ready(rtc);
+	if (ret == 0)
+		writel(val, rtc->base + reg);
+
+	return ret;
+}
+
+static int jz4740_rtc_ctrl_set_bits(struct jz4740_rtc *rtc, uint32_t mask,
+	bool set)
+{
+	int ret;
+	unsigned long flags;
+	uint32_t ctrl;
+
+	spin_lock_irqsave(&rtc->lock, flags);
+
+	ctrl = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_CTRL);
+
+	/* Don't clear interrupt flags by accident */
+	ctrl |= JZ_RTC_CTRL_1HZ | JZ_RTC_CTRL_AF;
+
+	if (set)
+		ctrl |= mask;
+	else
+		ctrl &= ~mask;
+
+	ret = jz4740_rtc_reg_write(rtc, JZ_REG_RTC_CTRL, ctrl);
+
+	spin_unlock_irqrestore(&rtc->lock, flags);
+
+	return ret;
+}
+
+static int jz4740_rtc_read_time(struct device *dev, struct rtc_time *time)
+{
+	struct jz4740_rtc *rtc = dev_get_drvdata(dev);
+	uint32_t secs, secs2;
+	int timeout = 5;
+
+	/* If the seconds register is read while it is updated, it can contain a
+	 * bogus value. This can be avoided by making sure that two consecutive
+	 * reads have the same value.
+	 */
+	secs = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_SEC);
+	secs2 = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_SEC);
+
+	while (secs != secs2 && --timeout) {
+		secs = secs2;
+		secs2 = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_SEC);
+	}
+
+	if (timeout == 0)
+		return -EIO;
+
+	rtc_time_to_tm(secs, time);
+
+	return rtc_valid_tm(time);
+}
+
+static int jz4740_rtc_set_mmss(struct device *dev, unsigned long secs)
+{
+	struct jz4740_rtc *rtc = dev_get_drvdata(dev);
+
+	return jz4740_rtc_reg_write(rtc, JZ_REG_RTC_SEC, secs);
+}
+
+static int jz4740_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct jz4740_rtc *rtc = dev_get_drvdata(dev);
+	uint32_t secs;
+	uint32_t ctrl;
+
+	secs = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_SEC_ALARM);
+
+	ctrl = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_CTRL);
+
+	alrm->enabled = !!(ctrl & JZ_RTC_CTRL_AE);
+	alrm->pending = !!(ctrl & JZ_RTC_CTRL_AF);
+
+	rtc_time_to_tm(secs, &alrm->time);
+
+	return rtc_valid_tm(&alrm->time);
+}
+
+static int jz4740_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	int ret;
+	struct jz4740_rtc *rtc = dev_get_drvdata(dev);
+	unsigned long secs;
+
+	rtc_tm_to_time(&alrm->time, &secs);
+
+	ret = jz4740_rtc_reg_write(rtc, JZ_REG_RTC_SEC_ALARM, secs);
+	if (!ret)
+		ret = jz4740_rtc_ctrl_set_bits(rtc, JZ_RTC_CTRL_AE, alrm->enabled);
+
+	return ret;
+}
+
+static int jz4740_rtc_update_irq_enable(struct device *dev, unsigned int enable)
+{
+	struct jz4740_rtc *rtc = dev_get_drvdata(dev);
+	return jz4740_rtc_ctrl_set_bits(rtc, JZ_RTC_CTRL_1HZ_IRQ, enable);
+}
+
+static int jz4740_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
+{
+	struct jz4740_rtc *rtc = dev_get_drvdata(dev);
+	return jz4740_rtc_ctrl_set_bits(rtc, JZ_RTC_CTRL_AF_IRQ, enable);
+}
+
+static struct rtc_class_ops jz4740_rtc_ops = {
+	.read_time	= jz4740_rtc_read_time,
+	.set_mmss	= jz4740_rtc_set_mmss,
+	.read_alarm	= jz4740_rtc_read_alarm,
+	.set_alarm	= jz4740_rtc_set_alarm,
+	.update_irq_enable = jz4740_rtc_update_irq_enable,
+	.alarm_irq_enable = jz4740_rtc_alarm_irq_enable,
+};
+
+static irqreturn_t jz4740_rtc_irq(int irq, void *data)
+{
+	struct jz4740_rtc *rtc = data;
+	uint32_t ctrl;
+	unsigned long events = 0;
+
+	ctrl = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_CTRL);
+
+	if (ctrl & JZ_RTC_CTRL_1HZ)
+		events |= (RTC_UF | RTC_IRQF);
+
+	if (ctrl & JZ_RTC_CTRL_AF)
+		events |= (RTC_AF | RTC_IRQF);
+
+	rtc_update_irq(rtc->rtc, 1, events);
+
+	jz4740_rtc_ctrl_set_bits(rtc, JZ_RTC_CTRL_1HZ | JZ_RTC_CTRL_AF, false);
+
+	return IRQ_HANDLED;
+}
+
+void jz4740_rtc_poweroff(struct device *dev)
+{
+	struct jz4740_rtc *rtc = dev_get_drvdata(dev);
+	jz4740_rtc_reg_write(rtc, JZ_REG_RTC_HIBERNATE, 1);
+}
+EXPORT_SYMBOL_GPL(jz4740_rtc_poweroff);
+
+static int __devinit jz4740_rtc_probe(struct platform_device *pdev)
+{
+	int ret;
+	struct jz4740_rtc *rtc;
+	uint32_t scratchpad;
+
+	rtc = kzalloc(sizeof(*rtc), GFP_KERNEL);
+	if (!rtc)
+		return -ENOMEM;
+
+	rtc->irq = platform_get_irq(pdev, 0);
+	if (rtc->irq < 0) {
+		ret = -ENOENT;
+		dev_err(&pdev->dev, "Failed to get platform irq\n");
+		goto err_free;
+	}
+
+	rtc->mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!rtc->mem) {
+		ret = -ENOENT;
+		dev_err(&pdev->dev, "Failed to get platform mmio memory\n");
+		goto err_free;
+	}
+
+	rtc->mem = request_mem_region(rtc->mem->start, resource_size(rtc->mem),
+					pdev->name);
+	if (!rtc->mem) {
+		ret = -EBUSY;
+		dev_err(&pdev->dev, "Failed to request mmio memory region\n");
+		goto err_free;
+	}
+
+	rtc->base = ioremap_nocache(rtc->mem->start, resource_size(rtc->mem));
+	if (!rtc->base) {
+		ret = -EBUSY;
+		dev_err(&pdev->dev, "Failed to ioremap mmio memory\n");
+		goto err_release_mem_region;
+	}
+
+	spin_lock_init(&rtc->lock);
+
+	platform_set_drvdata(pdev, rtc);
+
+	rtc->rtc = rtc_device_register(pdev->name, &pdev->dev, &jz4740_rtc_ops,
+					THIS_MODULE);
+	if (IS_ERR(rtc->rtc)) {
+		ret = PTR_ERR(rtc->rtc);
+		dev_err(&pdev->dev, "Failed to register rtc device: %d\n", ret);
+		goto err_iounmap;
+	}
+
+	ret = request_irq(rtc->irq, jz4740_rtc_irq, 0,
+				pdev->name, rtc);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to request rtc irq: %d\n", ret);
+		goto err_unregister_rtc;
+	}
+
+	scratchpad = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_SCRATCHPAD);
+	if (scratchpad != 0x12345678) {
+		ret = jz4740_rtc_reg_write(rtc, JZ_REG_RTC_SCRATCHPAD, 0x12345678);
+		ret = jz4740_rtc_reg_write(rtc, JZ_REG_RTC_SEC, 0);
+		if (ret) {
+			dev_err(&pdev->dev, "Could not write write to RTC registers\n");
+			goto err_free_irq;
+		}
+	}
+
+	return 0;
+
+err_free_irq:
+	free_irq(rtc->irq, rtc);
+err_unregister_rtc:
+	rtc_device_unregister(rtc->rtc);
+err_iounmap:
+	platform_set_drvdata(pdev, NULL);
+	iounmap(rtc->base);
+err_release_mem_region:
+	release_mem_region(rtc->mem->start, resource_size(rtc->mem));
+err_free:
+	kfree(rtc);
+
+	return ret;
+}
+
+static int __devexit jz4740_rtc_remove(struct platform_device *pdev)
+{
+	struct jz4740_rtc *rtc = platform_get_drvdata(pdev);
+
+	free_irq(rtc->irq, rtc);
+
+	rtc_device_unregister(rtc->rtc);
+
+	iounmap(rtc->base);
+	release_mem_region(rtc->mem->start, resource_size(rtc->mem));
+
+	kfree(rtc);
+
+	platform_set_drvdata(pdev, NULL);
+
+	return 0;
+}
+
+struct platform_driver jz4740_rtc_driver = {
+	.probe = jz4740_rtc_probe,
+	.remove = __devexit_p(jz4740_rtc_remove),
+	.driver = {
+		.name = "jz4740-rtc",
+		.owner = THIS_MODULE,
+	},
+};
+
+static int __init jz4740_rtc_init(void)
+{
+	return platform_driver_register(&jz4740_rtc_driver);
+}
+module_init(jz4740_rtc_init);
+
+static void __exit jz4740_rtc_exit(void)
+{
+	platform_driver_unregister(&jz4740_rtc_driver);
+}
+module_exit(jz4740_rtc_exit);
+
+MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("RTC driver for the JZ4740 SoC\n");
+MODULE_ALIAS("platform:jz4740-rtc");