[PATCH] rtc: add support for Freescale SNVS RTC
Shawn Guo
shawn.guo at linaro.org
Thu Mar 22 11:11:59 EDT 2012
On Mon, Mar 19, 2012 at 09:04:29PM +0800, Ying-Chun Liu (PaulLiu) wrote:
> From: "Ying-Chun Liu (PaulLiu)" <paul.liu at 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 at freescale.com>
> Signed-off-by: Eric Miao <eric.miao at linaro.org>
> Signed-off-by: Anson Huang <b20788 at freescale.com>
> Signed-off-by: Ying-Chun Liu (PaulLiu) <paul.liu at linaro.org>
> Cc: Alessandro Zummo <a.zummo at towertech.it>
> Cc: Shawn Guo <shawn.guo at 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 at freescale.com>, "
> + "Eric Miao <eric.miao at linaro.org>, "
> + "Anson Huang <b20788 at freescale.com>, "
> + "Ying-Chun Liu (PaulLiu) <paul.liu at linaro.org>");
> +MODULE_DESCRIPTION("SNVS Realtime Clock Driver (RTC)");
> +MODULE_LICENSE("GPL v2");
MODULE_ALIAS?
> --
> 1.7.9.1
>
--
Regards,
Shawn
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