Patchwork rtc: add support for Freescale SNVS RTC

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Submitter Ying-Chun Liu (PaulLiu)
Date March 19, 2012, 1:04 p.m.
Message ID <1332162269-16789-1-git-send-email-paul.liu@linaro.org>
Download mbox | patch
Permalink /patch/147506/
State New
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Comments

Ying-Chun Liu (PaulLiu) - March 19, 2012, 1:04 p.m.
From: "Ying-Chun Liu (PaulLiu)" <paul.liu@linaro.org>

This adds an RTC driver for the Low Power (LP) section of SNVS.
It hooks into the /dev/rtc interface and supports ioctl to complete RTC
features. This driver supports device tree bindings.
It only uses the RTC hw in non-secure mode.

Signed-off-by: Anish Trivedi <anish@freescale.com>
Signed-off-by: Eric Miao <eric.miao@linaro.org>
Signed-off-by: Anson Huang <b20788@freescale.com>
Signed-off-by: Ying-Chun Liu (PaulLiu) <paul.liu@linaro.org>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Shawn Guo <shawn.guo@linaro.org>
---
 drivers/rtc/Kconfig    |   11 +
 drivers/rtc/Makefile   |    1 +
 drivers/rtc/rtc-snvs.c |  737 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 749 insertions(+), 0 deletions(-)
 create mode 100644 drivers/rtc/rtc-snvs.c
Shawn Guo - March 22, 2012, 3:11 p.m.
On Mon, Mar 19, 2012 at 09:04:29PM +0800, Ying-Chun Liu (PaulLiu) wrote:
> From: "Ying-Chun Liu (PaulLiu)" <paul.liu@linaro.org>
> 
> This adds an RTC driver for the Low Power (LP) section of SNVS.
> It hooks into the /dev/rtc interface and supports ioctl to complete RTC
> features. This driver supports device tree bindings.

Then, you need to have a document in Documentation/devicetree/bindings.

> It only uses the RTC hw in non-secure mode.
> 
> Signed-off-by: Anish Trivedi <anish@freescale.com>
> Signed-off-by: Eric Miao <eric.miao@linaro.org>
> Signed-off-by: Anson Huang <b20788@freescale.com>
> Signed-off-by: Ying-Chun Liu (PaulLiu) <paul.liu@linaro.org>
> Cc: Alessandro Zummo <a.zummo@towertech.it>
> Cc: Shawn Guo <shawn.guo@linaro.org>
> ---
>  drivers/rtc/Kconfig    |   11 +
>  drivers/rtc/Makefile   |    1 +
>  drivers/rtc/rtc-snvs.c |  737 ++++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 749 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/rtc/rtc-snvs.c
> 
> diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
> index 3a125b8..d58f4b7 100644
> --- a/drivers/rtc/Kconfig
> +++ b/drivers/rtc/Kconfig
> @@ -634,6 +634,17 @@ config RTC_MXC
>  	   This driver can also be built as a module, if so, the module
>  	   will be called "rtc-mxc".
>  
> +config RTC_DRV_SNVS
> +	tristate "Freescale SNVS Real Time Clock"
> +	depends on ARCH_MXC
> +	depends on RTC_CLASS

I'm not sure this is really necessary, since this config is included
in "if RTC_CLASS".

> +	help
> +	   If you say yes here you get support for the Freescale SNVS
> +	   Low Power (LP) RTC module.
> +
> +	   This driver can also be built as a module, if so, the module
> +	   will be called "rtc-snvs".
> +
>  config RTC_DRV_BQ4802
>  	tristate "TI BQ4802"
>  	help
> diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
> index 6e69823..8b30686 100644
> --- a/drivers/rtc/Makefile
> +++ b/drivers/rtc/Makefile
> @@ -93,6 +93,7 @@ obj-$(CONFIG_RTC_DRV_S35390A)	+= rtc-s35390a.o
>  obj-$(CONFIG_RTC_DRV_S3C)	+= rtc-s3c.o
>  obj-$(CONFIG_RTC_DRV_SA1100)	+= rtc-sa1100.o
>  obj-$(CONFIG_RTC_DRV_SH)	+= rtc-sh.o
> +obj-$(CONFIG_RTC_DRV_SNVS)	+= rtc-snvs.o
>  obj-$(CONFIG_RTC_DRV_SPEAR)	+= rtc-spear.o
>  obj-$(CONFIG_RTC_DRV_STARFIRE)	+= rtc-starfire.o
>  obj-$(CONFIG_RTC_DRV_STK17TA8)	+= rtc-stk17ta8.o
> diff --git a/drivers/rtc/rtc-snvs.c b/drivers/rtc/rtc-snvs.c
> new file mode 100644
> index 0000000..49ac8a5
> --- /dev/null
> +++ b/drivers/rtc/rtc-snvs.c
> @@ -0,0 +1,737 @@
> +/*
> + * Copyright (C) 2011 Freescale Semiconductor, Inc.
> + */
> +
> +/*
> + * 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.
> + *
> + * 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.
> + *
> + * 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.,
> + * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
> + */
> +/*
> + * Implementation based on rtc-ds1553.c
> + */
> +
> +/*!

I'm not sure "/*!" is the format for kernel-doc.  Please take a look
at Documentation/kernel-doc-nano-HOWTO.txt.

> + * @defgroup RTC Real Time Clock (RTC) Driver
> + */
> +/*!
> + * @file rtc-snvs.c
> + * @brief Secure Real Time Clock (SRTC) interface in Freescale's SNVS module
> + *
> + * This file contains Real Time Clock interface for Linux. The Freescale
> + * SNVS module's Low Power (LP) SRTC functionality is utilized in this driver,
> + * in non-secure mode.
> + *
> + * @ingroup RTC
> + */
> +
I feel above several sections of documents can just be in one multiple
line comment section.

> +#include <linux/slab.h>
> +#include <linux/delay.h>
> +#include <linux/rtc.h>
> +#include <linux/module.h>
> +#include <linux/fs.h>
> +#include <linux/init.h>
> +#include <linux/interrupt.h>
> +#include <linux/platform_device.h>
> +#include <linux/uaccess.h>
> +#include <linux/io.h>
> +#include <linux/sched.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +
> +/* Register definitions */
> +#define	SNVS_HPSR	0x14	/* HP Status Register */

Normally, we have one space rather than tab after "#define".

> +#define	SNVS_LPCR	0x38	/* LP Control Register */
> +#define	SNVS_LPSR	0x4C	/* LP Status Register */
> +#define	SNVS_LPSRTCMR	0x50	/* LP Secure Real Time Counter MSB Register */
> +#define	SNVS_LPSRTCLR	0x54	/* LP Secure Real Time Counter LSB Register */
> +#define	SNVS_LPTAR	0x58	/* LP Time Alarm Register */
> +#define	SNVS_LPSMCMR	0x5C	/* LP Secure Monotonic Counter MSB Register */
> +#define	SNVS_LPSMCLR	0x60	/* LP Secure Monotonic Counter LSB Register */
> +#define	SNVS_LPPGDR	0x64	/* LP Power Glitch Detector Register */
> +#define	SNVS_LPGPR	0x68	/* LP General Purpose Register */
> +
> +/* Bit Definitions */
> +#define	SNVS_HPSR_SSM_ST_MASK	0x00000F00
> +#define	SNVS_HPSR_SSM_ST_SHIFT	8
> +
> +#define	SNVS_LPCR_SRTC_ENV	(1 << 0)
> +#define	SNVS_LPCR_LPTA_EN	(1 << 1)
> +#define	SNVS_LPCR_LPWUI_EN	(1 << 3)
> +#define	SNVS_LPCR_ALL_INT_EN (SNVS_LPCR_LPTA_EN | SNVS_LPCR_LPWUI_EN)

Align the indentation?

> +#define	SNVS_LPSR_LPTA		(1 << 0)
> +#define	SNVS_LPPGDR_INIT	0x41736166
> +
> +/* Other defines */
> +#define	SSM_ST_CHECK	0x9
> +#define	SSM_ST_NON_SECURE	0xB
> +#define	CNTR_TO_SECS_SH 15	/* Converts 47-bit counter to 32-bit seconds */

Ditto

> +
> +#define RTC_READ_TIME_47BIT	_IOR('p', 0x20, unsigned long long)
> +/* blocks until LPSCMR is set, returns difference */
> +#define RTC_WAIT_TIME_SET	_IOR('p', 0x21, int64_t)
> +

What are these local ioctl number exactly for?  How can user space
use these driver private numbers?

> +struct rtc_drv_data {
> +	struct rtc_device *rtc;
> +	void __iomem *ioaddr;
> +	int irq;
> +	bool irq_enable;
> +};
> +
> +static unsigned long rtc_status;
> +
> +static DEFINE_SPINLOCK(rtc_lock);
> +DECLARE_COMPLETION(snvs_completion);
> +static int64_t time_diff;
> +
> +/*!
> + * LP counter register reads should always use this function.
> + * This function reads 2 consective times from LP counter register
> + * until the 2 values match. This is to avoid reading corrupt
> + * value if the counter is in the middle of updating
> + */

If you write kernel doc for functions, please follow the format
documented in Dcumentation/kernel-doc-nano-HOWTO.txt

> +static inline u32 rtc_read_lp_counter(void __iomem *counter_reg)
> +{
> +	u64 read1, read2;
> +	u32 counter_sec;
> +
> +	do {
> +		/* MSB */
> +		read1 = readl(counter_reg);
> +		read1 <<= 32;
> +		/* LSB */
> +		read1 |= readl(counter_reg + 4);
> +
> +		/* MSB */
> +		read2 = readl(counter_reg);
> +		read2 <<= 32;
> +		/* LSB */
> +		read2 |= readl(counter_reg + 4);
> +	} while (read1 != read2);
> +
> +	/* Convert 47-bit counter to 32-bit raw second count */
> +	counter_sec = (u32) (read1 >> CNTR_TO_SECS_SH);
> +
> +	return counter_sec;
> +}
> +
It seems the function is only used to read register SNVS_LPSRTCMR, just
like that the function below is only writing register SNVS_LPSRTCLR.
Why they are using different semantics.  The above function takes
register address as argument while the following one takes snvs base
address?

> +/*!
> + * This function does write synchronization for writes to the lp srtc block.
> + * To take care of the asynchronous CKIL clock, all writes from the IP domain
> + * will be synchronized to the CKIL domain.
> + */
> +static inline void rtc_write_sync_lp(void __iomem *ioaddr)
> +{
> +	unsigned int i, count1, count2, count3;
> +
> +	/* Wait for 3 CKIL cycles */
> +	for (i = 0; i < 3; i++) {

Each loop consumes 1 CKIL cycle?

> +
> +		/* Do consective reads of LSB of counter to ensure integrity */
> +		do {
> +			count1 = readl(ioaddr + SNVS_LPSRTCLR);
> +			count2 = readl(ioaddr + SNVS_LPSRTCLR);
> +		} while (count1 != count2);
> +
> +		/* Now wait until counter value changes */
> +		do {
> +			do {
> +				count2 = readl(ioaddr + SNVS_LPSRTCLR);
> +				count3 = readl(ioaddr + SNVS_LPSRTCLR);
> +			} while (count2 != count3);
> +		} while (count3 == count1);
> +	}
> +}
> +
> +/*!
> + * This function updates the RTC alarm registers and then clears all the
> + * interrupt status bits.
> + *
> + * @param  alrm         the new alarm value to be updated in the RTC
> + *
> + * @return  0 if successful; non-zero otherwise.
> + */
> +static int rtc_update_alarm(struct device *dev, struct rtc_time *alrm)
> +{
> +	struct rtc_drv_data *pdata = dev_get_drvdata(dev);
> +	void __iomem *ioaddr = pdata->ioaddr;
> +	struct rtc_time alarm_tm, now_tm;
> +	unsigned long now, time, lp_cr;
> +	int ret;
> +
> +	now = rtc_read_lp_counter(ioaddr + SNVS_LPSRTCMR);
> +	rtc_time_to_tm(now, &now_tm);
> +
> +	alarm_tm.tm_year = now_tm.tm_year;
> +	alarm_tm.tm_mon = now_tm.tm_mon;
> +	alarm_tm.tm_mday = now_tm.tm_mday;
> +
> +	alarm_tm.tm_hour = alrm->tm_hour;
> +	alarm_tm.tm_min = alrm->tm_min;
> +	alarm_tm.tm_sec = alrm->tm_sec;
> +
> +	rtc_tm_to_time(&now_tm, &now);
> +	rtc_tm_to_time(&alarm_tm, &time);
> +
> +	if (time < now) {
> +		time += 60 * 60 * 24;
> +		rtc_time_to_tm(time, &alarm_tm);
> +	}
> +	ret = rtc_tm_to_time(&alarm_tm, &time);
> +
> +	/* Have to clear LPTA_EN before programming new alarm time in LPTAR */
> +	lp_cr = readl(ioaddr + SNVS_LPCR);
> +	writel(lp_cr & ~SNVS_LPCR_LPTA_EN, ioaddr + SNVS_LPCR);
> +	rtc_write_sync_lp(ioaddr);
> +
> +	writel(time, ioaddr + SNVS_LPTAR);
> +
> +	/* clear alarm interrupt status bit */
> +	writel(SNVS_LPSR_LPTA, ioaddr + SNVS_LPSR);
> +
> +	return ret;
> +}
> +
> +/*!
> + * This function is the RTC interrupt service routine.
> + *
> + * @param  irq          RTC IRQ number
> + * @param  dev_id       device ID which is not used
> + *
> + * @return IRQ_HANDLED as defined in the include/linux/interrupt.h file.
> + */
> +static irqreturn_t snvs_rtc_interrupt(int irq, void *dev_id)
> +{
> +	struct platform_device *pdev = dev_id;
> +	struct rtc_drv_data *pdata = platform_get_drvdata(pdev);
> +	void __iomem *ioaddr = pdata->ioaddr;
> +	u32 lp_status, lp_cr;
> +	u32 events = 0;
> +
> +	lp_status = readl(ioaddr + SNVS_LPSR);
> +	lp_cr = readl(ioaddr + SNVS_LPCR);
> +
> +	/* update irq data & counter */
> +	if (lp_status & SNVS_LPSR_LPTA) {
> +		if (lp_cr & SNVS_LPCR_LPTA_EN)
> +			events |= (RTC_AF | RTC_IRQF);
> +
> +		/* disable further lp alarm interrupts */
> +		lp_cr &= ~(SNVS_LPCR_LPTA_EN | SNVS_LPCR_LPWUI_EN);
> +	}
> +
> +	/* Update interrupt enables */
> +	writel(lp_cr, ioaddr + SNVS_LPCR);
> +
> +	/* If no interrupts are enabled, turn off interrupts in kernel */
> +	if (((lp_cr & SNVS_LPCR_ALL_INT_EN) == 0) && (pdata->irq_enable)) {
> +		disable_irq_nosync(pdata->irq);
> +		pdata->irq_enable = false;
> +	}
> +
> +	/* clear interrupt status */
> +	writel(lp_status, ioaddr + SNVS_LPSR);
> +
> +	rtc_write_sync_lp(ioaddr);
> +	rtc_update_irq(pdata->rtc, 1, events);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +/*!
> + * This function is used to open the RTC driver.
> + *
> + * @return  0 if successful; non-zero otherwise.
> + */
> +static int snvs_rtc_open(struct device *dev)
> +{
> +	if (test_and_set_bit(1, &rtc_status))
> +		return -EBUSY;
> +
> +	return 0;
> +}
> +
> +/*!
> + * clear all interrupts and release the IRQ
> + */
> +static void snvs_rtc_release(struct device *dev)
> +{
> +	rtc_status = 0;
> +}
> +

This couple of hooks seem completely unnecessary to me, since they do
nothing but just checking reentry, which has been done by rtc core.

> +/*!
> + * This function reads the current RTC time into tm in Gregorian date.
> + *
> + * @param  tm           contains the RTC time value upon return
> + *
> + * @return  0 if successful; non-zero otherwise.
> + */
> +static int snvs_rtc_read_time(struct device *dev, struct rtc_time *tm)
> +{
> +	struct rtc_drv_data *pdata = dev_get_drvdata(dev);
> +	void __iomem *ioaddr = pdata->ioaddr;
> +
> +	rtc_time_to_tm(rtc_read_lp_counter(ioaddr + SNVS_LPSRTCMR), tm);
> +
> +	return 0;
> +}
> +
> +/*!
> + * This function sets the internal RTC time based on tm in Gregorian date.
> + *
> + * @param  tm           the time value to be set in the RTC
> + *
> + * @return  0 if successful; non-zero otherwise.
> + */
> +static int snvs_rtc_set_time(struct device *dev, struct rtc_time *tm)
> +{
> +	struct rtc_drv_data *pdata = dev_get_drvdata(dev);
> +	void __iomem *ioaddr = pdata->ioaddr;
> +	unsigned long time;
> +	int ret;
> +	u32 lp_cr;
> +	u64 old_time_47bit, new_time_47bit;
> +
> +	ret = rtc_tm_to_time(tm, &time);
> +	if (ret != 0)
> +		return ret;
> +
> +	old_time_47bit = (((u64) (readl(ioaddr + SNVS_LPSRTCMR) &
> +		((0x1 << CNTR_TO_SECS_SH) - 1)) << 32) |
> +		((u64) readl(ioaddr + SNVS_LPSRTCLR)));
> +
> +	/* Disable RTC first */
> +	lp_cr = readl(ioaddr + SNVS_LPCR) & ~SNVS_LPCR_SRTC_ENV;
> +	writel(lp_cr, ioaddr + SNVS_LPCR);
> +	while (readl(ioaddr + SNVS_LPCR) & SNVS_LPCR_SRTC_ENV)
> +		;

Don't you need proper timeout?

> +
> +	/* Write 32-bit time to 47-bit timer, leaving 15 LSBs blank */
> +	writel(time << CNTR_TO_SECS_SH, ioaddr + SNVS_LPSRTCLR);
> +	writel(time >> (32 - CNTR_TO_SECS_SH), ioaddr + SNVS_LPSRTCMR);
> +
> +	/* Enable RTC again */
> +	writel(lp_cr | SNVS_LPCR_SRTC_ENV, ioaddr + SNVS_LPCR);
> +	while (!(readl(ioaddr + SNVS_LPCR) & SNVS_LPCR_SRTC_ENV))
> +		;

Ditto

> +
> +	rtc_write_sync_lp(ioaddr);
> +
> +	new_time_47bit = (((u64) (readl(ioaddr + SNVS_LPSRTCMR) &
> +		((0x1 << CNTR_TO_SECS_SH) - 1)) << 32) |
> +		((u64) readl(ioaddr + SNVS_LPSRTCLR)));
> +
> +	time_diff = new_time_47bit - old_time_47bit;
> +
> +	/* signal all waiting threads that time changed */
> +	complete_all(&snvs_completion);
> +
> +	/* allow signalled threads to handle the time change notification */
> +	schedule();
> +
> +	/* reinitialize completion variable */
> +	INIT_COMPLETION(snvs_completion);
> +

Are you sure all these sync need to get done in driver?

> +	return 0;
> +}
> +
> +/*!
> + * This function reads the current alarm value into the passed in \b alrm
> + * argument. It updates the \b alrm's pending field value based on the whether
> + * an alarm interrupt occurs or not.
> + *
> + * @param  alrm         contains the RTC alarm value upon return
> + *
> + * @return  0 if successful; non-zero otherwise.
> + */
> +static int snvs_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
> +{
> +	struct rtc_drv_data *pdata = dev_get_drvdata(dev);
> +	void __iomem *ioaddr = pdata->ioaddr;
> +
> +	rtc_time_to_tm(readl(ioaddr + SNVS_LPTAR), &alrm->time);
> +	alrm->pending =
> +	    ((readl(ioaddr + SNVS_LPSR) & SNVS_LPSR_LPTA) != 0) ? 1 : 0;
> +
> +	return 0;
> +}
> +
> +/*!
> + * This function sets the RTC alarm based on passed in alrm.
> + *
> + * @param  alrm         the alarm value to be set in the RTC
> + *
> + * @return  0 if successful; non-zero otherwise.
> + */
> +static int snvs_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
> +{
> +	struct rtc_drv_data *pdata = dev_get_drvdata(dev);
> +	void __iomem *ioaddr = pdata->ioaddr;
> +	unsigned long lock_flags = 0;
> +	u32 lp_cr;
> +	int ret;
> +
> +	if (rtc_valid_tm(&alrm->time)) {
> +		if (alrm->time.tm_sec > 59 ||
> +		    alrm->time.tm_hour > 23 || alrm->time.tm_min > 59) {

Haven't all these checking been covered by rtc_valid_tm()?

> +			return -EINVAL;
> +		}
> +	}
> +
> +	spin_lock_irqsave(&rtc_lock, lock_flags);
> +
> +	ret = rtc_update_alarm(dev, &alrm->time);
> +	if (ret)
> +		goto out;
> +
> +	lp_cr = readl(ioaddr + SNVS_LPCR);
> +
> +	if (alrm->enabled)
> +		lp_cr |= (SNVS_LPCR_LPTA_EN | SNVS_LPCR_LPWUI_EN);
> +	else
> +		lp_cr &= ~(SNVS_LPCR_LPTA_EN | SNVS_LPCR_LPWUI_EN);
> +
> +	if (lp_cr & SNVS_LPCR_ALL_INT_EN) {
> +		if (!pdata->irq_enable) {
> +			enable_irq(pdata->irq);
> +			pdata->irq_enable = true;
> +		}
> +	} else {
> +		if (pdata->irq_enable) {
> +			disable_irq(pdata->irq);
> +			pdata->irq_enable = false;
> +		}
> +	}
> +
> +	writel(lp_cr, ioaddr + SNVS_LPCR);
> +
> +out:
> +	rtc_write_sync_lp(ioaddr);
> +	spin_unlock_irqrestore(&rtc_lock, lock_flags);
> +
> +	return ret;
> +}
> +
> +/*!
> + * This function is used to provide the content for the /proc/driver/rtc
> + * file.
> + *
> + * @param  seq  buffer to hold the information that the driver wants to write
> + *
> + * @return  The number of bytes written into the rtc file.
> + */
> +static int snvs_rtc_proc(struct device *dev, struct seq_file *seq)
> +{
> +	struct rtc_drv_data *pdata = dev_get_drvdata(dev);
> +	void __iomem *ioaddr = pdata->ioaddr;
> +
> +	seq_printf(seq, "alarm_IRQ\t: %s\n",
> +		   (((readl(ioaddr + SNVS_LPCR)) & SNVS_LPCR_LPTA_EN) !=
> +		    0) ? "yes" : "no");
> +
> +	return 0;
> +}
> +
> +static int snvs_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
> +{
> +	struct rtc_drv_data *pdata = dev_get_drvdata(dev);
> +	void __iomem *ioaddr = pdata->ioaddr;
> +	u32 lp_cr;
> +	unsigned long lock_flags = 0;
> +
> +	spin_lock_irqsave(&rtc_lock, lock_flags);
> +
> +	if (enable) {
> +		if (!pdata->irq_enable) {
> +			enable_irq(pdata->irq);
> +			pdata->irq_enable = true;
> +		}
> +		lp_cr = readl(ioaddr + SNVS_LPCR);
> +		lp_cr |= (SNVS_LPCR_LPTA_EN | SNVS_LPCR_LPWUI_EN);
> +		writel(lp_cr, ioaddr + SNVS_LPCR);
> +	} else {
> +		lp_cr = readl(ioaddr + SNVS_LPCR);
> +		lp_cr &= ~(SNVS_LPCR_LPTA_EN | SNVS_LPCR_LPWUI_EN);
> +		if (((lp_cr & SNVS_LPCR_ALL_INT_EN) == 0)
> +		    && (pdata->irq_enable)) {
> +			disable_irq(pdata->irq);
> +			pdata->irq_enable = false;
> +		}
> +		writel(lp_cr, ioaddr + SNVS_LPCR);
> +	}
> +
> +	rtc_write_sync_lp(ioaddr);
> +	spin_unlock_irqrestore(&rtc_lock, lock_flags);
> +
> +	return 0;
> +}
> +
> +/*!
> + * This function is used to support some ioctl calls directly.
> + * Other ioctl calls are supported indirectly through the
> + * arm/common/rtctime.c file.
> + *
> + * @param  cmd          ioctl command as defined in include/linux/rtc.h
> + * @param  arg          value for the ioctl command
> + *
> + * @return  0 if successful or negative value otherwise.
> + */
> +static int snvs_rtc_ioctl(struct device *dev, unsigned int cmd,
> +			 unsigned long arg)
> +{
> +	struct rtc_drv_data *pdata = dev_get_drvdata(dev);
> +	void __iomem *ioaddr = pdata->ioaddr;
> +	u64 time_47bit;
> +	int retVal;
> +
> +	switch (cmd) {
> +	case RTC_READ_TIME_47BIT:
> +		time_47bit = (((u64) (readl(ioaddr + SNVS_LPSRTCMR) &
> +			((0x1 << CNTR_TO_SECS_SH) - 1)) << 32) |
> +			((u64) readl(ioaddr + SNVS_LPSRTCLR)));
> +
> +		if (arg && copy_to_user((u64 *) arg, &time_47bit, sizeof(u64)))
> +			return -EFAULT;
> +
> +		return 0;
> +
> +	/* This IOCTL to be used by processes to be notified of time changes */
> +	case RTC_WAIT_TIME_SET:
> +		/* don't block without releasing mutex first */
> +		mutex_unlock(&pdata->rtc->ops_lock);
> +
> +		/* sleep till awakened by SRTC driver when LPSCMR is changed */
> +		wait_for_completion(&snvs_completion);
> +
> +		/* relock mutex because rtc_dev_ioctl will unlock again */
> +		retVal = mutex_lock_interruptible(&pdata->rtc->ops_lock);
> +
> +		/* copy the new time difference = new time - previous time
> +		 * to the user param. The difference is a signed value */
> +		if (arg && copy_to_user((int64_t *) arg, &time_diff,
> +			sizeof(int64_t)))
> +			return -EFAULT;
> +
> +		return retVal;
> +
> +	}
> +
> +	return -ENOIOCTLCMD;
> +}

I haven't completely understood this, and will need more study.

> +
> +/*!
> + * The RTC driver structure
> + */
> +static struct rtc_class_ops snvs_rtc_ops = {
> +	.open = snvs_rtc_open,
> +	.release = snvs_rtc_release,
> +	.read_time = snvs_rtc_read_time,
> +	.set_time = snvs_rtc_set_time,
> +	.read_alarm = snvs_rtc_read_alarm,
> +	.set_alarm = snvs_rtc_set_alarm,
> +	.proc = snvs_rtc_proc,
> +	.ioctl = snvs_rtc_ioctl,
> +	.alarm_irq_enable = snvs_rtc_alarm_irq_enable,
> +};
> +
> +/*! SNVS RTC Power management control */
> +static int __devinit snvs_rtc_probe(struct platform_device *pdev)
> +{
> +	struct timespec tv;
> +	struct resource *res;
> +	struct rtc_device *rtc;
> +	struct rtc_drv_data *pdata = NULL;
> +	void __iomem *ioaddr;
> +	u32 lp_cr;
> +	int ret = 0;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!res)
> +		return -ENODEV;
> +
> +	ioaddr = ioremap(res->start, resource_size(res));
> +	if (!ioaddr)
> +		return -EADDRNOTAVAIL;

Use of_iomap() can save the call of platform_get_resource().

> +
> +	pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
> +	if (!pdata)
> +		return -ENOMEM;
> +
> +	pdata->ioaddr = ioaddr;
> +
> +	/* Configure and enable the RTC */
> +	pdata->irq = platform_get_irq(pdev, 0);
> +	if (pdata->irq >= 0) {
> +		if (request_irq(pdata->irq, snvs_rtc_interrupt, IRQF_SHARED,
> +				pdev->name, pdev) < 0) {
> +			dev_warn(&pdev->dev, "interrupt not available.\n");
> +			pdata->irq = -1;
> +		} else {
> +			disable_irq(pdata->irq);
> +			pdata->irq_enable = false;
> +		}
> +	}
> +
> +	/* initialize glitch detect */
> +	writel(SNVS_LPPGDR_INIT, ioaddr + SNVS_LPPGDR);
> +	udelay(100);
> +
> +	/* clear lp interrupt status */
> +	writel(0xFFFFFFFF, ioaddr + SNVS_LPSR);
> +
> +	/* Enable RTC */
> +	lp_cr = readl(ioaddr + SNVS_LPCR);
> +	if ((lp_cr & SNVS_LPCR_SRTC_ENV) == 0)
> +		writel(lp_cr | SNVS_LPCR_SRTC_ENV, ioaddr + SNVS_LPCR);
> +
> +	udelay(100);
> +
> +	writel(0xFFFFFFFF, ioaddr + SNVS_LPSR);
> +	udelay(100);

All these udelay calls are necessary?

> +
> +	platform_set_drvdata(pdev, pdata);
> +
> +	rtc = rtc_device_register(pdev->name, &pdev->dev,
> +				  &snvs_rtc_ops, THIS_MODULE);
> +	if (IS_ERR(rtc)) {
> +		ret = PTR_ERR(rtc);
> +		goto err_out;
> +	}
> +
> +	pdata->rtc = rtc;
> +
> +	tv.tv_nsec = 0;
> +	tv.tv_sec = rtc_read_lp_counter(ioaddr + SNVS_LPSRTCMR);
> +
> +	/* By default, devices should wakeup if they can */
> +	/* So snvs is set as "should wakeup" as it can */
> +	device_init_wakeup(&pdev->dev, 1);
> +
> +	return ret;
> +
> +err_out:
> +	iounmap(ioaddr);
> +	if (pdata->irq >= 0)
> +		free_irq(pdata->irq, pdev);
> +
> +	return ret;
> +}
> +
> +static int __devexit snvs_rtc_remove(struct platform_device *pdev)
> +{
> +	struct rtc_drv_data *pdata = platform_get_drvdata(pdev);
> +	rtc_device_unregister(pdata->rtc);
> +	if (pdata->irq >= 0)
> +		free_irq(pdata->irq, pdev);
> +	iounmap(pdata->ioaddr);
> +
> +	return 0;
> +}
> +
> +/*!
> + * This function is called to save the system time delta relative to
> + * the SNVS RTC when enterring a low power state. This time delta is
> + * then used on resume to adjust the system time to account for time
> + * loss while suspended.
> + *
> + * @param   pdev  not used
> + * @param   state Power state to enter.
> + *
> + * @return  The function always returns 0.
> + */
> +static int snvs_rtc_suspend(struct platform_device *pdev, pm_message_t state)
> +{
> +	struct rtc_drv_data *pdata = platform_get_drvdata(pdev);
> +
> +	if (device_may_wakeup(&pdev->dev)) {
> +		enable_irq_wake(pdata->irq);
> +	} else {
> +		if (pdata->irq_enable)
> +			disable_irq(pdata->irq);
> +	}
> +
> +	return 0;
> +}
> +
> +/*!
> + * This function is called to correct the system time based on the
> + * current SNVS RTC time relative to the time delta saved during
> + * suspend.
> + *
> + * @param   pdev  not used
> + *
> + * @return  The function always returns 0.
> + */
> +static int snvs_rtc_resume(struct platform_device *pdev)
> +{
> +	struct rtc_drv_data *pdata = platform_get_drvdata(pdev);
> +
> +	if (device_may_wakeup(&pdev->dev)) {
> +		disable_irq_wake(pdata->irq);
> +	} else {
> +		if (pdata->irq_enable)
> +			enable_irq(pdata->irq);
> +	}
> +
> +	return 0;
> +}
> +

Shouldn't these 2 functions be wrapped by #ifdef CONFIG_PM?

> +static const struct of_device_id __devinitdata snvs_dt_ids[] = {
> +	{ .compatible = "fsl,snvs" },

"fsl,snvs-rtc"?

> +	{ /* sentinel */ }
> +};
> +
> +/*!
> + * Contains pointers to the power management callback functions.
> + */
> +static struct platform_driver snvs_rtc_driver = {
> +	.driver = {
> +		.name	= "snvs_rtc",
> +		.owner	= THIS_MODULE,
> +		.of_match_table = snvs_dt_ids,
> +	},
> +	.probe = snvs_rtc_probe,
> +	.remove = __exit_p(snvs_rtc_remove),
> +	.suspend = snvs_rtc_suspend,
> +	.resume = snvs_rtc_resume,
> +};
> +

...
> +/*!
> + * This function creates the /proc/driver/rtc file and registers the device RTC
> + * in the /dev/misc directory. It also reads the RTC value from external source
> + * and setup the internal RTC properly.
> + *
> + * @return  -1 if RTC is failed to initialize; 0 is successful.
> + */
> +static int __init snvs_rtc_init(void)
> +{
> +	return platform_driver_register(&snvs_rtc_driver);
> +}
> +module_init(snvs_rtc_init);
> +
> +/*!
> + * This function removes the /proc/driver/rtc file and un-registers the
> + * device RTC from the /dev/misc directory.
> + */
> +static void __exit snvs_rtc_exit(void)
> +{
> +	platform_driver_unregister(&snvs_rtc_driver);
> +}
> +module_exit(snvs_rtc_exit);

These can just be module_platform_driver(snvs_rtc_driver)?

> +
> +MODULE_AUTHOR("Anish Trivedi <anish@freescale.com>, "
> +	      "Eric Miao <eric.miao@linaro.org>, "
> +	      "Anson Huang <b20788@freescale.com>, "
> +	      "Ying-Chun Liu (PaulLiu) <paul.liu@linaro.org>");
> +MODULE_DESCRIPTION("SNVS Realtime Clock Driver (RTC)");
> +MODULE_LICENSE("GPL v2");

MODULE_ALIAS?

> -- 
> 1.7.9.1
>
Ying-Chun Liu (PaulLiu) - April 13, 2012, 4:16 p.m.
(2012年03月22日 23:11), Shawn Guo wrote:
> On Mon, Mar 19, 2012 at 09:04:29PM +0800, Ying-Chun Liu (PaulLiu) wrote:
>> +
>> +#define RTC_READ_TIME_47BIT	_IOR('p', 0x20, unsigned long long)
>> +/* blocks until LPSCMR is set, returns difference */
>> +#define RTC_WAIT_TIME_SET	_IOR('p', 0x21, int64_t)
>> +
> 
> What are these local ioctl number exactly for?  How can user space
> use these driver private numbers?
> 
>> +
>> +	rtc_write_sync_lp(ioaddr);
>> +
>> +	new_time_47bit = (((u64) (readl(ioaddr + SNVS_LPSRTCMR) &
>> +		((0x1 << CNTR_TO_SECS_SH) - 1)) << 32) |
>> +		((u64) readl(ioaddr + SNVS_LPSRTCLR)));
>> +
>> +	time_diff = new_time_47bit - old_time_47bit;
>> +
>> +	/* signal all waiting threads that time changed */
>> +	complete_all(&snvs_completion);
>> +
>> +	/* allow signalled threads to handle the time change notification */
>> +	schedule();
>> +
>> +	/* reinitialize completion variable */
>> +	INIT_COMPLETION(snvs_completion);
>> +
> 
> Are you sure all these sync need to get done in driver?
> 
>> +			return -EINVAL;
>> +		}
>> +	}
>> +
>> +	spin_lock_irqsave(&rtc_lock, lock_flags);
>> +
>> +	ret = rtc_update_alarm(dev, &alrm->time);
>> +	if (ret)
>> +		goto out;
>> +
>> +	lp_cr = readl(ioaddr + SNVS_LPCR);
>> +
>> +	if (alrm->enabled)
>> +		lp_cr |= (SNVS_LPCR_LPTA_EN | SNVS_LPCR_LPWUI_EN);
>> +	else
>> +		lp_cr &= ~(SNVS_LPCR_LPTA_EN | SNVS_LPCR_LPWUI_EN);
>> +
>> +	if (lp_cr & SNVS_LPCR_ALL_INT_EN) {
>> +		if (!pdata->irq_enable) {
>> +			enable_irq(pdata->irq);
>> +			pdata->irq_enable = true;
>> +		}
>> +	} else {
>> +		if (pdata->irq_enable) {
>> +			disable_irq(pdata->irq);
>> +			pdata->irq_enable = false;
>> +		}
>> +	}
>> +
>> +	writel(lp_cr, ioaddr + SNVS_LPCR);
>> +
>> +out:
>> +	rtc_write_sync_lp(ioaddr);
>> +	spin_unlock_irqrestore(&rtc_lock, lock_flags);
>> +
>> +	return ret;
>> +}
>> +
>> +/*!
>> + * This function is used to provide the content for the /proc/driver/rtc
>> + * file.
>> + *
>> + * @param  seq  buffer to hold the information that the driver wants to write
>> + *
>> + * @return  The number of bytes written into the rtc file.
>> + */
>> +static int snvs_rtc_proc(struct device *dev, struct seq_file *seq)
>> +{
>> +	struct rtc_drv_data *pdata = dev_get_drvdata(dev);
>> +	void __iomem *ioaddr = pdata->ioaddr;
>> +
>> +	seq_printf(seq, "alarm_IRQ\t: %s\n",
>> +		   (((readl(ioaddr + SNVS_LPCR)) & SNVS_LPCR_LPTA_EN) !=
>> +		    0) ? "yes" : "no");
>> +
>> +	return 0;
>> +}
>> +
>> +static int snvs_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
>> +{
>> +	struct rtc_drv_data *pdata = dev_get_drvdata(dev);
>> +	void __iomem *ioaddr = pdata->ioaddr;
>> +	u32 lp_cr;
>> +	unsigned long lock_flags = 0;
>> +
>> +	spin_lock_irqsave(&rtc_lock, lock_flags);
>> +
>> +	if (enable) {
>> +		if (!pdata->irq_enable) {
>> +			enable_irq(pdata->irq);
>> +			pdata->irq_enable = true;
>> +		}
>> +		lp_cr = readl(ioaddr + SNVS_LPCR);
>> +		lp_cr |= (SNVS_LPCR_LPTA_EN | SNVS_LPCR_LPWUI_EN);
>> +		writel(lp_cr, ioaddr + SNVS_LPCR);
>> +	} else {
>> +		lp_cr = readl(ioaddr + SNVS_LPCR);
>> +		lp_cr &= ~(SNVS_LPCR_LPTA_EN | SNVS_LPCR_LPWUI_EN);
>> +		if (((lp_cr & SNVS_LPCR_ALL_INT_EN) == 0)
>> +		    && (pdata->irq_enable)) {
>> +			disable_irq(pdata->irq);
>> +			pdata->irq_enable = false;
>> +		}
>> +		writel(lp_cr, ioaddr + SNVS_LPCR);
>> +	}
>> +
>> +	rtc_write_sync_lp(ioaddr);
>> +	spin_unlock_irqrestore(&rtc_lock, lock_flags);
>> +
>> +	return 0;
>> +}
>> +
>> +/*!
>> + * This function is used to support some ioctl calls directly.
>> + * Other ioctl calls are supported indirectly through the
>> + * arm/common/rtctime.c file.
>> + *
>> + * @param  cmd          ioctl command as defined in include/linux/rtc.h
>> + * @param  arg          value for the ioctl command
>> + *
>> + * @return  0 if successful or negative value otherwise.
>> + */
>> +static int snvs_rtc_ioctl(struct device *dev, unsigned int cmd,
>> +			 unsigned long arg)
>> +{
>> +	struct rtc_drv_data *pdata = dev_get_drvdata(dev);
>> +	void __iomem *ioaddr = pdata->ioaddr;
>> +	u64 time_47bit;
>> +	int retVal;
>> +
>> +	switch (cmd) {
>> +	case RTC_READ_TIME_47BIT:
>> +		time_47bit = (((u64) (readl(ioaddr + SNVS_LPSRTCMR) &
>> +			((0x1 << CNTR_TO_SECS_SH) - 1)) << 32) |
>> +			((u64) readl(ioaddr + SNVS_LPSRTCLR)));
>> +
>> +		if (arg && copy_to_user((u64 *) arg, &time_47bit, sizeof(u64)))
>> +			return -EFAULT;
>> +
>> +		return 0;
>> +
>> +	/* This IOCTL to be used by processes to be notified of time changes */
>> +	case RTC_WAIT_TIME_SET:
>> +		/* don't block without releasing mutex first */
>> +		mutex_unlock(&pdata->rtc->ops_lock);
>> +
>> +		/* sleep till awakened by SRTC driver when LPSCMR is changed */
>> +		wait_for_completion(&snvs_completion);
>> +
>> +		/* relock mutex because rtc_dev_ioctl will unlock again */
>> +		retVal = mutex_lock_interruptible(&pdata->rtc->ops_lock);
>> +
>> +		/* copy the new time difference = new time - previous time
>> +		 * to the user param. The difference is a signed value */
>> +		if (arg && copy_to_user((int64_t *) arg, &time_diff,
>> +			sizeof(int64_t)))
>> +			return -EFAULT;
>> +
>> +		return retVal;
>> +
>> +	}
>> +
>> +	return -ENOIOCTLCMD;
>> +}
> 
> I haven't completely understood this, and will need more study.
> 

Hi Shawn,

About the above ioctl() related blocks. I think it is used by some user
space libs that requires accurate time (47BIT TIME). And it have to be
sure that the time continuously flowing so the apps wants to be notified
that the rtc is changed dramatically by the set command.

I'm guessing that it might be related to the Multimedia binary libs. A/V
sync or something like that. But I don't have those source code. Please
make sure those libs are not using it.

I also see other Freescale RTC driver implement the same function. For
example:
http://tinyurl.com/cnp93jv
So I guess it might be a common ioctl that Freescale uses somewhere.

So my plan is to split the IOR to a header file. And keep the rest as is.

Yours Sincerely,
Paul
Sascha Hauer - April 13, 2012, 8:18 p.m.
On Sat, Apr 14, 2012 at 12:16:26AM +0800, Ying-Chun Liu (PaulLiu) wrote:
> > 
> > I haven't completely understood this, and will need more study.
> > 
> 
> Hi Shawn,
> 
> About the above ioctl() related blocks. I think it is used by some user
> space libs that requires accurate time (47BIT TIME). And it have to be
> sure that the time continuously flowing so the apps wants to be notified
> that the rtc is changed dramatically by the set command.
> 
> I'm guessing that it might be related to the Multimedia binary libs. A/V
> sync or something like that. But I don't have those source code. Please
> make sure those libs are not using it.
> 
> I also see other Freescale RTC driver implement the same function. For
> example:
> http://tinyurl.com/cnp93jv
> So I guess it might be a common ioctl that Freescale uses somewhere.
> 
> So my plan is to split the IOR to a header file. And keep the rest as is.

'think', 'might' and 'something like that' are the wrong words to
convince anybody that these ioctls are needed. So unless you find real
usecases and also can convince us that it's not possible to reach your
goal using either the existing ioctls or an additional common (non fsl
specific) ioctl please just drop them.

Sascha

Patch

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 3a125b8..d58f4b7 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -634,6 +634,17 @@  config RTC_MXC
 	   This driver can also be built as a module, if so, the module
 	   will be called "rtc-mxc".
 
+config RTC_DRV_SNVS
+	tristate "Freescale SNVS Real Time Clock"
+	depends on ARCH_MXC
+	depends on RTC_CLASS
+	help
+	   If you say yes here you get support for the Freescale SNVS
+	   Low Power (LP) RTC module.
+
+	   This driver can also be built as a module, if so, the module
+	   will be called "rtc-snvs".
+
 config RTC_DRV_BQ4802
 	tristate "TI BQ4802"
 	help
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 6e69823..8b30686 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -93,6 +93,7 @@  obj-$(CONFIG_RTC_DRV_S35390A)	+= rtc-s35390a.o
 obj-$(CONFIG_RTC_DRV_S3C)	+= rtc-s3c.o
 obj-$(CONFIG_RTC_DRV_SA1100)	+= rtc-sa1100.o
 obj-$(CONFIG_RTC_DRV_SH)	+= rtc-sh.o
+obj-$(CONFIG_RTC_DRV_SNVS)	+= rtc-snvs.o
 obj-$(CONFIG_RTC_DRV_SPEAR)	+= rtc-spear.o
 obj-$(CONFIG_RTC_DRV_STARFIRE)	+= rtc-starfire.o
 obj-$(CONFIG_RTC_DRV_STK17TA8)	+= rtc-stk17ta8.o
diff --git a/drivers/rtc/rtc-snvs.c b/drivers/rtc/rtc-snvs.c
new file mode 100644
index 0000000..49ac8a5
--- /dev/null
+++ b/drivers/rtc/rtc-snvs.c
@@ -0,0 +1,737 @@ 
+/*
+ * Copyright (C) 2011 Freescale Semiconductor, Inc.
+ */
+
+/*
+ * 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.
+ *
+ * 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.
+ *
+ * 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.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+/*
+ * Implementation based on rtc-ds1553.c
+ */
+
+/*!
+ * @defgroup RTC Real Time Clock (RTC) Driver
+ */
+/*!
+ * @file rtc-snvs.c
+ * @brief Secure Real Time Clock (SRTC) interface in Freescale's SNVS module
+ *
+ * This file contains Real Time Clock interface for Linux. The Freescale
+ * SNVS module's Low Power (LP) SRTC functionality is utilized in this driver,
+ * in non-secure mode.
+ *
+ * @ingroup RTC
+ */
+
+#include <linux/slab.h>
+#include <linux/delay.h>
+#include <linux/rtc.h>
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+#include <linux/uaccess.h>
+#include <linux/io.h>
+#include <linux/sched.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+
+/* Register definitions */
+#define	SNVS_HPSR	0x14	/* HP Status Register */
+#define	SNVS_LPCR	0x38	/* LP Control Register */
+#define	SNVS_LPSR	0x4C	/* LP Status Register */
+#define	SNVS_LPSRTCMR	0x50	/* LP Secure Real Time Counter MSB Register */
+#define	SNVS_LPSRTCLR	0x54	/* LP Secure Real Time Counter LSB Register */
+#define	SNVS_LPTAR	0x58	/* LP Time Alarm Register */
+#define	SNVS_LPSMCMR	0x5C	/* LP Secure Monotonic Counter MSB Register */
+#define	SNVS_LPSMCLR	0x60	/* LP Secure Monotonic Counter LSB Register */
+#define	SNVS_LPPGDR	0x64	/* LP Power Glitch Detector Register */
+#define	SNVS_LPGPR	0x68	/* LP General Purpose Register */
+
+/* Bit Definitions */
+#define	SNVS_HPSR_SSM_ST_MASK	0x00000F00
+#define	SNVS_HPSR_SSM_ST_SHIFT	8
+
+#define	SNVS_LPCR_SRTC_ENV	(1 << 0)
+#define	SNVS_LPCR_LPTA_EN	(1 << 1)
+#define	SNVS_LPCR_LPWUI_EN	(1 << 3)
+#define	SNVS_LPCR_ALL_INT_EN (SNVS_LPCR_LPTA_EN | SNVS_LPCR_LPWUI_EN)
+#define	SNVS_LPSR_LPTA		(1 << 0)
+#define	SNVS_LPPGDR_INIT	0x41736166
+
+/* Other defines */
+#define	SSM_ST_CHECK	0x9
+#define	SSM_ST_NON_SECURE	0xB
+#define	CNTR_TO_SECS_SH 15	/* Converts 47-bit counter to 32-bit seconds */
+
+#define RTC_READ_TIME_47BIT	_IOR('p', 0x20, unsigned long long)
+/* blocks until LPSCMR is set, returns difference */
+#define RTC_WAIT_TIME_SET	_IOR('p', 0x21, int64_t)
+
+struct rtc_drv_data {
+	struct rtc_device *rtc;
+	void __iomem *ioaddr;
+	int irq;
+	bool irq_enable;
+};
+
+static unsigned long rtc_status;
+
+static DEFINE_SPINLOCK(rtc_lock);
+DECLARE_COMPLETION(snvs_completion);
+static int64_t time_diff;
+
+/*!
+ * LP counter register reads should always use this function.
+ * This function reads 2 consective times from LP counter register
+ * until the 2 values match. This is to avoid reading corrupt
+ * value if the counter is in the middle of updating
+ */
+static inline u32 rtc_read_lp_counter(void __iomem *counter_reg)
+{
+	u64 read1, read2;
+	u32 counter_sec;
+
+	do {
+		/* MSB */
+		read1 = readl(counter_reg);
+		read1 <<= 32;
+		/* LSB */
+		read1 |= readl(counter_reg + 4);
+
+		/* MSB */
+		read2 = readl(counter_reg);
+		read2 <<= 32;
+		/* LSB */
+		read2 |= readl(counter_reg + 4);
+	} while (read1 != read2);
+
+	/* Convert 47-bit counter to 32-bit raw second count */
+	counter_sec = (u32) (read1 >> CNTR_TO_SECS_SH);
+
+	return counter_sec;
+}
+
+/*!
+ * This function does write synchronization for writes to the lp srtc block.
+ * To take care of the asynchronous CKIL clock, all writes from the IP domain
+ * will be synchronized to the CKIL domain.
+ */
+static inline void rtc_write_sync_lp(void __iomem *ioaddr)
+{
+	unsigned int i, count1, count2, count3;
+
+	/* Wait for 3 CKIL cycles */
+	for (i = 0; i < 3; i++) {
+
+		/* Do consective reads of LSB of counter to ensure integrity */
+		do {
+			count1 = readl(ioaddr + SNVS_LPSRTCLR);
+			count2 = readl(ioaddr + SNVS_LPSRTCLR);
+		} while (count1 != count2);
+
+		/* Now wait until counter value changes */
+		do {
+			do {
+				count2 = readl(ioaddr + SNVS_LPSRTCLR);
+				count3 = readl(ioaddr + SNVS_LPSRTCLR);
+			} while (count2 != count3);
+		} while (count3 == count1);
+	}
+}
+
+/*!
+ * This function updates the RTC alarm registers and then clears all the
+ * interrupt status bits.
+ *
+ * @param  alrm         the new alarm value to be updated in the RTC
+ *
+ * @return  0 if successful; non-zero otherwise.
+ */
+static int rtc_update_alarm(struct device *dev, struct rtc_time *alrm)
+{
+	struct rtc_drv_data *pdata = dev_get_drvdata(dev);
+	void __iomem *ioaddr = pdata->ioaddr;
+	struct rtc_time alarm_tm, now_tm;
+	unsigned long now, time, lp_cr;
+	int ret;
+
+	now = rtc_read_lp_counter(ioaddr + SNVS_LPSRTCMR);
+	rtc_time_to_tm(now, &now_tm);
+
+	alarm_tm.tm_year = now_tm.tm_year;
+	alarm_tm.tm_mon = now_tm.tm_mon;
+	alarm_tm.tm_mday = now_tm.tm_mday;
+
+	alarm_tm.tm_hour = alrm->tm_hour;
+	alarm_tm.tm_min = alrm->tm_min;
+	alarm_tm.tm_sec = alrm->tm_sec;
+
+	rtc_tm_to_time(&now_tm, &now);
+	rtc_tm_to_time(&alarm_tm, &time);
+
+	if (time < now) {
+		time += 60 * 60 * 24;
+		rtc_time_to_tm(time, &alarm_tm);
+	}
+	ret = rtc_tm_to_time(&alarm_tm, &time);
+
+	/* Have to clear LPTA_EN before programming new alarm time in LPTAR */
+	lp_cr = readl(ioaddr + SNVS_LPCR);
+	writel(lp_cr & ~SNVS_LPCR_LPTA_EN, ioaddr + SNVS_LPCR);
+	rtc_write_sync_lp(ioaddr);
+
+	writel(time, ioaddr + SNVS_LPTAR);
+
+	/* clear alarm interrupt status bit */
+	writel(SNVS_LPSR_LPTA, ioaddr + SNVS_LPSR);
+
+	return ret;
+}
+
+/*!
+ * This function is the RTC interrupt service routine.
+ *
+ * @param  irq          RTC IRQ number
+ * @param  dev_id       device ID which is not used
+ *
+ * @return IRQ_HANDLED as defined in the include/linux/interrupt.h file.
+ */
+static irqreturn_t snvs_rtc_interrupt(int irq, void *dev_id)
+{
+	struct platform_device *pdev = dev_id;
+	struct rtc_drv_data *pdata = platform_get_drvdata(pdev);
+	void __iomem *ioaddr = pdata->ioaddr;
+	u32 lp_status, lp_cr;
+	u32 events = 0;
+
+	lp_status = readl(ioaddr + SNVS_LPSR);
+	lp_cr = readl(ioaddr + SNVS_LPCR);
+
+	/* update irq data & counter */
+	if (lp_status & SNVS_LPSR_LPTA) {
+		if (lp_cr & SNVS_LPCR_LPTA_EN)
+			events |= (RTC_AF | RTC_IRQF);
+
+		/* disable further lp alarm interrupts */
+		lp_cr &= ~(SNVS_LPCR_LPTA_EN | SNVS_LPCR_LPWUI_EN);
+	}
+
+	/* Update interrupt enables */
+	writel(lp_cr, ioaddr + SNVS_LPCR);
+
+	/* If no interrupts are enabled, turn off interrupts in kernel */
+	if (((lp_cr & SNVS_LPCR_ALL_INT_EN) == 0) && (pdata->irq_enable)) {
+		disable_irq_nosync(pdata->irq);
+		pdata->irq_enable = false;
+	}
+
+	/* clear interrupt status */
+	writel(lp_status, ioaddr + SNVS_LPSR);
+
+	rtc_write_sync_lp(ioaddr);
+	rtc_update_irq(pdata->rtc, 1, events);
+
+	return IRQ_HANDLED;
+}
+
+/*!
+ * This function is used to open the RTC driver.
+ *
+ * @return  0 if successful; non-zero otherwise.
+ */
+static int snvs_rtc_open(struct device *dev)
+{
+	if (test_and_set_bit(1, &rtc_status))
+		return -EBUSY;
+
+	return 0;
+}
+
+/*!
+ * clear all interrupts and release the IRQ
+ */
+static void snvs_rtc_release(struct device *dev)
+{
+	rtc_status = 0;
+}
+
+/*!
+ * This function reads the current RTC time into tm in Gregorian date.
+ *
+ * @param  tm           contains the RTC time value upon return
+ *
+ * @return  0 if successful; non-zero otherwise.
+ */
+static int snvs_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct rtc_drv_data *pdata = dev_get_drvdata(dev);
+	void __iomem *ioaddr = pdata->ioaddr;
+
+	rtc_time_to_tm(rtc_read_lp_counter(ioaddr + SNVS_LPSRTCMR), tm);
+
+	return 0;
+}
+
+/*!
+ * This function sets the internal RTC time based on tm in Gregorian date.
+ *
+ * @param  tm           the time value to be set in the RTC
+ *
+ * @return  0 if successful; non-zero otherwise.
+ */
+static int snvs_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct rtc_drv_data *pdata = dev_get_drvdata(dev);
+	void __iomem *ioaddr = pdata->ioaddr;
+	unsigned long time;
+	int ret;
+	u32 lp_cr;
+	u64 old_time_47bit, new_time_47bit;
+
+	ret = rtc_tm_to_time(tm, &time);
+	if (ret != 0)
+		return ret;
+
+	old_time_47bit = (((u64) (readl(ioaddr + SNVS_LPSRTCMR) &
+		((0x1 << CNTR_TO_SECS_SH) - 1)) << 32) |
+		((u64) readl(ioaddr + SNVS_LPSRTCLR)));
+
+	/* Disable RTC first */
+	lp_cr = readl(ioaddr + SNVS_LPCR) & ~SNVS_LPCR_SRTC_ENV;
+	writel(lp_cr, ioaddr + SNVS_LPCR);
+	while (readl(ioaddr + SNVS_LPCR) & SNVS_LPCR_SRTC_ENV)
+		;
+
+	/* Write 32-bit time to 47-bit timer, leaving 15 LSBs blank */
+	writel(time << CNTR_TO_SECS_SH, ioaddr + SNVS_LPSRTCLR);
+	writel(time >> (32 - CNTR_TO_SECS_SH), ioaddr + SNVS_LPSRTCMR);
+
+	/* Enable RTC again */
+	writel(lp_cr | SNVS_LPCR_SRTC_ENV, ioaddr + SNVS_LPCR);
+	while (!(readl(ioaddr + SNVS_LPCR) & SNVS_LPCR_SRTC_ENV))
+		;
+
+	rtc_write_sync_lp(ioaddr);
+
+	new_time_47bit = (((u64) (readl(ioaddr + SNVS_LPSRTCMR) &
+		((0x1 << CNTR_TO_SECS_SH) - 1)) << 32) |
+		((u64) readl(ioaddr + SNVS_LPSRTCLR)));
+
+	time_diff = new_time_47bit - old_time_47bit;
+
+	/* signal all waiting threads that time changed */
+	complete_all(&snvs_completion);
+
+	/* allow signalled threads to handle the time change notification */
+	schedule();
+
+	/* reinitialize completion variable */
+	INIT_COMPLETION(snvs_completion);
+
+	return 0;
+}
+
+/*!
+ * This function reads the current alarm value into the passed in \b alrm
+ * argument. It updates the \b alrm's pending field value based on the whether
+ * an alarm interrupt occurs or not.
+ *
+ * @param  alrm         contains the RTC alarm value upon return
+ *
+ * @return  0 if successful; non-zero otherwise.
+ */
+static int snvs_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct rtc_drv_data *pdata = dev_get_drvdata(dev);
+	void __iomem *ioaddr = pdata->ioaddr;
+
+	rtc_time_to_tm(readl(ioaddr + SNVS_LPTAR), &alrm->time);
+	alrm->pending =
+	    ((readl(ioaddr + SNVS_LPSR) & SNVS_LPSR_LPTA) != 0) ? 1 : 0;
+
+	return 0;
+}
+
+/*!
+ * This function sets the RTC alarm based on passed in alrm.
+ *
+ * @param  alrm         the alarm value to be set in the RTC
+ *
+ * @return  0 if successful; non-zero otherwise.
+ */
+static int snvs_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct rtc_drv_data *pdata = dev_get_drvdata(dev);
+	void __iomem *ioaddr = pdata->ioaddr;
+	unsigned long lock_flags = 0;
+	u32 lp_cr;
+	int ret;
+
+	if (rtc_valid_tm(&alrm->time)) {
+		if (alrm->time.tm_sec > 59 ||
+		    alrm->time.tm_hour > 23 || alrm->time.tm_min > 59) {
+			return -EINVAL;
+		}
+	}
+
+	spin_lock_irqsave(&rtc_lock, lock_flags);
+
+	ret = rtc_update_alarm(dev, &alrm->time);
+	if (ret)
+		goto out;
+
+	lp_cr = readl(ioaddr + SNVS_LPCR);
+
+	if (alrm->enabled)
+		lp_cr |= (SNVS_LPCR_LPTA_EN | SNVS_LPCR_LPWUI_EN);
+	else
+		lp_cr &= ~(SNVS_LPCR_LPTA_EN | SNVS_LPCR_LPWUI_EN);
+
+	if (lp_cr & SNVS_LPCR_ALL_INT_EN) {
+		if (!pdata->irq_enable) {
+			enable_irq(pdata->irq);
+			pdata->irq_enable = true;
+		}
+	} else {
+		if (pdata->irq_enable) {
+			disable_irq(pdata->irq);
+			pdata->irq_enable = false;
+		}
+	}
+
+	writel(lp_cr, ioaddr + SNVS_LPCR);
+
+out:
+	rtc_write_sync_lp(ioaddr);
+	spin_unlock_irqrestore(&rtc_lock, lock_flags);
+
+	return ret;
+}
+
+/*!
+ * This function is used to provide the content for the /proc/driver/rtc
+ * file.
+ *
+ * @param  seq  buffer to hold the information that the driver wants to write
+ *
+ * @return  The number of bytes written into the rtc file.
+ */
+static int snvs_rtc_proc(struct device *dev, struct seq_file *seq)
+{
+	struct rtc_drv_data *pdata = dev_get_drvdata(dev);
+	void __iomem *ioaddr = pdata->ioaddr;
+
+	seq_printf(seq, "alarm_IRQ\t: %s\n",
+		   (((readl(ioaddr + SNVS_LPCR)) & SNVS_LPCR_LPTA_EN) !=
+		    0) ? "yes" : "no");
+
+	return 0;
+}
+
+static int snvs_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
+{
+	struct rtc_drv_data *pdata = dev_get_drvdata(dev);
+	void __iomem *ioaddr = pdata->ioaddr;
+	u32 lp_cr;
+	unsigned long lock_flags = 0;
+
+	spin_lock_irqsave(&rtc_lock, lock_flags);
+
+	if (enable) {
+		if (!pdata->irq_enable) {
+			enable_irq(pdata->irq);
+			pdata->irq_enable = true;
+		}
+		lp_cr = readl(ioaddr + SNVS_LPCR);
+		lp_cr |= (SNVS_LPCR_LPTA_EN | SNVS_LPCR_LPWUI_EN);
+		writel(lp_cr, ioaddr + SNVS_LPCR);
+	} else {
+		lp_cr = readl(ioaddr + SNVS_LPCR);
+		lp_cr &= ~(SNVS_LPCR_LPTA_EN | SNVS_LPCR_LPWUI_EN);
+		if (((lp_cr & SNVS_LPCR_ALL_INT_EN) == 0)
+		    && (pdata->irq_enable)) {
+			disable_irq(pdata->irq);
+			pdata->irq_enable = false;
+		}
+		writel(lp_cr, ioaddr + SNVS_LPCR);
+	}
+
+	rtc_write_sync_lp(ioaddr);
+	spin_unlock_irqrestore(&rtc_lock, lock_flags);
+
+	return 0;
+}
+
+/*!
+ * This function is used to support some ioctl calls directly.
+ * Other ioctl calls are supported indirectly through the
+ * arm/common/rtctime.c file.
+ *
+ * @param  cmd          ioctl command as defined in include/linux/rtc.h
+ * @param  arg          value for the ioctl command
+ *
+ * @return  0 if successful or negative value otherwise.
+ */
+static int snvs_rtc_ioctl(struct device *dev, unsigned int cmd,
+			 unsigned long arg)
+{
+	struct rtc_drv_data *pdata = dev_get_drvdata(dev);
+	void __iomem *ioaddr = pdata->ioaddr;
+	u64 time_47bit;
+	int retVal;
+
+	switch (cmd) {
+	case RTC_READ_TIME_47BIT:
+		time_47bit = (((u64) (readl(ioaddr + SNVS_LPSRTCMR) &
+			((0x1 << CNTR_TO_SECS_SH) - 1)) << 32) |
+			((u64) readl(ioaddr + SNVS_LPSRTCLR)));
+
+		if (arg && copy_to_user((u64 *) arg, &time_47bit, sizeof(u64)))
+			return -EFAULT;
+
+		return 0;
+
+	/* This IOCTL to be used by processes to be notified of time changes */
+	case RTC_WAIT_TIME_SET:
+		/* don't block without releasing mutex first */
+		mutex_unlock(&pdata->rtc->ops_lock);
+
+		/* sleep till awakened by SRTC driver when LPSCMR is changed */
+		wait_for_completion(&snvs_completion);
+
+		/* relock mutex because rtc_dev_ioctl will unlock again */
+		retVal = mutex_lock_interruptible(&pdata->rtc->ops_lock);
+
+		/* copy the new time difference = new time - previous time
+		 * to the user param. The difference is a signed value */
+		if (arg && copy_to_user((int64_t *) arg, &time_diff,
+			sizeof(int64_t)))
+			return -EFAULT;
+
+		return retVal;
+
+	}
+
+	return -ENOIOCTLCMD;
+}
+
+/*!
+ * The RTC driver structure
+ */
+static struct rtc_class_ops snvs_rtc_ops = {
+	.open = snvs_rtc_open,
+	.release = snvs_rtc_release,
+	.read_time = snvs_rtc_read_time,
+	.set_time = snvs_rtc_set_time,
+	.read_alarm = snvs_rtc_read_alarm,
+	.set_alarm = snvs_rtc_set_alarm,
+	.proc = snvs_rtc_proc,
+	.ioctl = snvs_rtc_ioctl,
+	.alarm_irq_enable = snvs_rtc_alarm_irq_enable,
+};
+
+/*! SNVS RTC Power management control */
+static int __devinit snvs_rtc_probe(struct platform_device *pdev)
+{
+	struct timespec tv;
+	struct resource *res;
+	struct rtc_device *rtc;
+	struct rtc_drv_data *pdata = NULL;
+	void __iomem *ioaddr;
+	u32 lp_cr;
+	int ret = 0;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -ENODEV;
+
+	ioaddr = ioremap(res->start, resource_size(res));
+	if (!ioaddr)
+		return -EADDRNOTAVAIL;
+
+	pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
+	if (!pdata)
+		return -ENOMEM;
+
+	pdata->ioaddr = ioaddr;
+
+	/* Configure and enable the RTC */
+	pdata->irq = platform_get_irq(pdev, 0);
+	if (pdata->irq >= 0) {
+		if (request_irq(pdata->irq, snvs_rtc_interrupt, IRQF_SHARED,
+				pdev->name, pdev) < 0) {
+			dev_warn(&pdev->dev, "interrupt not available.\n");
+			pdata->irq = -1;
+		} else {
+			disable_irq(pdata->irq);
+			pdata->irq_enable = false;
+		}
+	}
+
+	/* initialize glitch detect */
+	writel(SNVS_LPPGDR_INIT, ioaddr + SNVS_LPPGDR);
+	udelay(100);
+
+	/* clear lp interrupt status */
+	writel(0xFFFFFFFF, ioaddr + SNVS_LPSR);
+
+	/* Enable RTC */
+	lp_cr = readl(ioaddr + SNVS_LPCR);
+	if ((lp_cr & SNVS_LPCR_SRTC_ENV) == 0)
+		writel(lp_cr | SNVS_LPCR_SRTC_ENV, ioaddr + SNVS_LPCR);
+
+	udelay(100);
+
+	writel(0xFFFFFFFF, ioaddr + SNVS_LPSR);
+	udelay(100);
+
+	platform_set_drvdata(pdev, pdata);
+
+	rtc = rtc_device_register(pdev->name, &pdev->dev,
+				  &snvs_rtc_ops, THIS_MODULE);
+	if (IS_ERR(rtc)) {
+		ret = PTR_ERR(rtc);
+		goto err_out;
+	}
+
+	pdata->rtc = rtc;
+
+	tv.tv_nsec = 0;
+	tv.tv_sec = rtc_read_lp_counter(ioaddr + SNVS_LPSRTCMR);
+
+	/* By default, devices should wakeup if they can */
+	/* So snvs is set as "should wakeup" as it can */
+	device_init_wakeup(&pdev->dev, 1);
+
+	return ret;
+
+err_out:
+	iounmap(ioaddr);
+	if (pdata->irq >= 0)
+		free_irq(pdata->irq, pdev);
+
+	return ret;
+}
+
+static int __devexit snvs_rtc_remove(struct platform_device *pdev)
+{
+	struct rtc_drv_data *pdata = platform_get_drvdata(pdev);
+	rtc_device_unregister(pdata->rtc);
+	if (pdata->irq >= 0)
+		free_irq(pdata->irq, pdev);
+	iounmap(pdata->ioaddr);
+
+	return 0;
+}
+
+/*!
+ * This function is called to save the system time delta relative to
+ * the SNVS RTC when enterring a low power state. This time delta is
+ * then used on resume to adjust the system time to account for time
+ * loss while suspended.
+ *
+ * @param   pdev  not used
+ * @param   state Power state to enter.
+ *
+ * @return  The function always returns 0.
+ */
+static int snvs_rtc_suspend(struct platform_device *pdev, pm_message_t state)
+{
+	struct rtc_drv_data *pdata = platform_get_drvdata(pdev);
+
+	if (device_may_wakeup(&pdev->dev)) {
+		enable_irq_wake(pdata->irq);
+	} else {
+		if (pdata->irq_enable)
+			disable_irq(pdata->irq);
+	}
+
+	return 0;
+}
+
+/*!
+ * This function is called to correct the system time based on the
+ * current SNVS RTC time relative to the time delta saved during
+ * suspend.
+ *
+ * @param   pdev  not used
+ *
+ * @return  The function always returns 0.
+ */
+static int snvs_rtc_resume(struct platform_device *pdev)
+{
+	struct rtc_drv_data *pdata = platform_get_drvdata(pdev);
+
+	if (device_may_wakeup(&pdev->dev)) {
+		disable_irq_wake(pdata->irq);
+	} else {
+		if (pdata->irq_enable)
+			enable_irq(pdata->irq);
+	}
+
+	return 0;
+}
+
+static const struct of_device_id __devinitdata snvs_dt_ids[] = {
+	{ .compatible = "fsl,snvs" },
+	{ /* sentinel */ }
+};
+
+/*!
+ * Contains pointers to the power management callback functions.
+ */
+static struct platform_driver snvs_rtc_driver = {
+	.driver = {
+		.name	= "snvs_rtc",
+		.owner	= THIS_MODULE,
+		.of_match_table = snvs_dt_ids,
+	},
+	.probe = snvs_rtc_probe,
+	.remove = __exit_p(snvs_rtc_remove),
+	.suspend = snvs_rtc_suspend,
+	.resume = snvs_rtc_resume,
+};
+
+/*!
+ * This function creates the /proc/driver/rtc file and registers the device RTC
+ * in the /dev/misc directory. It also reads the RTC value from external source
+ * and setup the internal RTC properly.
+ *
+ * @return  -1 if RTC is failed to initialize; 0 is successful.
+ */
+static int __init snvs_rtc_init(void)
+{
+	return platform_driver_register(&snvs_rtc_driver);
+}
+module_init(snvs_rtc_init);
+
+/*!
+ * This function removes the /proc/driver/rtc file and un-registers the
+ * device RTC from the /dev/misc directory.
+ */
+static void __exit snvs_rtc_exit(void)
+{
+	platform_driver_unregister(&snvs_rtc_driver);
+}
+module_exit(snvs_rtc_exit);
+
+MODULE_AUTHOR("Anish Trivedi <anish@freescale.com>, "
+	      "Eric Miao <eric.miao@linaro.org>, "
+	      "Anson Huang <b20788@freescale.com>, "
+	      "Ying-Chun Liu (PaulLiu) <paul.liu@linaro.org>");
+MODULE_DESCRIPTION("SNVS Realtime Clock Driver (RTC)");
+MODULE_LICENSE("GPL v2");