Re: [PATCH 3/8] rtc: add STM32 RTC driver

From: Amelie DELAUNAY
Date: Mon Dec 05 2016 - 04:44:39 EST

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Hi Mathieu,

Thanks for reviewing

On 12/02/2016 06:56 PM, Mathieu Poirier wrote:
> On Fri, Dec 02, 2016 at 03:09:56PM +0100, Amelie Delaunay wrote:
>> This patch adds support for the STM32 RTC.
>
> Hello Amelie,
>
>>
>> Signed-off-by: Amelie Delaunay <amelie.delaunay@xxxxxx>
>> ---
>> drivers/rtc/Kconfig | 10 +
>> drivers/rtc/Makefile | 1 +
>> drivers/rtc/rtc-stm32.c | 777 ++++++++++++++++++++++++++++++++++++++++++++++++
>> 3 files changed, 788 insertions(+)
>> create mode 100644 drivers/rtc/rtc-stm32.c
>>
>> diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
>> index e859d14..dd8b218 100644
>> --- a/drivers/rtc/Kconfig
>> +++ b/drivers/rtc/Kconfig
>> @@ -1706,6 +1706,16 @@ config RTC_DRV_PIC32
>> This driver can also be built as a module. If so, the module
>> will be called rtc-pic32
>>
>> +config RTC_DRV_STM32
>> + tristate "STM32 On-Chip RTC"
>> + depends on ARCH_STM32
>> + help
>> + If you say yes here you get support for the STM32 On-Chip
>> + Real Time Clock.
>> +
>> + This driver can also be built as a module, if so, the module
>> + will be called "rtc-stm32".
>> +
>> comment "HID Sensor RTC drivers"
>>
>> config RTC_DRV_HID_SENSOR_TIME
>> diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
>> index 1ac694a..87bd9cc 100644
>> --- a/drivers/rtc/Makefile
>> +++ b/drivers/rtc/Makefile
>> @@ -144,6 +144,7 @@ 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
>> +obj-$(CONFIG_RTC_DRV_STM32) += rtc-stm32.o
>> obj-$(CONFIG_RTC_DRV_STMP) += rtc-stmp3xxx.o
>> obj-$(CONFIG_RTC_DRV_ST_LPC) += rtc-st-lpc.o
>> obj-$(CONFIG_RTC_DRV_SUN4V) += rtc-sun4v.o
>> diff --git a/drivers/rtc/rtc-stm32.c b/drivers/rtc/rtc-stm32.c
>> new file mode 100644
>> index 0000000..9e710ff
>> --- /dev/null
>> +++ b/drivers/rtc/rtc-stm32.c
>> @@ -0,0 +1,777 @@
>> +/*
>> + * Copyright (C) Amelie Delaunay 2015
>> + * Author: Amelie Delaunay <adelaunay.stm32@xxxxxxxxx>
>> + * License terms: GNU General Public License (GPL), version 2
>> + */
>> +
>> +#include <linux/bcd.h>
>> +#include <linux/clk.h>
>> +#include <linux/init.h>
>> +#include <linux/io.h>
>> +#include <linux/iopoll.h>
>> +#include <linux/ioport.h>
>> +#include <linux/kernel.h>
>> +#include <linux/mfd/syscon.h>
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>> +#include <linux/of_device.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/regmap.h>
>> +#include <linux/rtc.h>
>> +#include <linux/spinlock.h>
>> +
>> +#define DRIVER_NAME "stm32_rtc"
>> +
>> +/* STM32 RTC registers */
>> +#define STM32_RTC_TR 0x00
>> +#define STM32_RTC_DR 0x04
>> +#define STM32_RTC_CR 0x08
>> +#define STM32_RTC_ISR 0x0C
>> +#define STM32_RTC_PRER 0x10
>> +#define STM32_RTC_ALRMAR 0x1C
>> +#define STM32_RTC_WPR 0x24
>> +
>> +/* STM32_RTC_TR bit fields */
>> +#define STM32_RTC_TR_SEC_SHIFT 0
>> +#define STM32_RTC_TR_SEC GENMASK(6, 0)
>> +#define STM32_RTC_TR_MIN_SHIFT 8
>> +#define STM32_RTC_TR_MIN GENMASK(14, 8)
>> +#define STM32_RTC_TR_HOUR_SHIFT 16
>> +#define STM32_RTC_TR_HOUR GENMASK(21, 16)
>> +
>> +/* STM32_RTC_DR bit fields */
>> +#define STM32_RTC_DR_DATE_SHIFT 0
>> +#define STM32_RTC_DR_DATE GENMASK(5, 0)
>> +#define STM32_RTC_DR_MONTH_SHIFT 8
>> +#define STM32_RTC_DR_MONTH GENMASK(11, 8)
>> +#define STM32_RTC_DR_WDAY_SHIFT 13
>> +#define STM32_RTC_DR_WDAY GENMASK(15, 13)
>> +#define STM32_RTC_DR_YEAR_SHIFT 16
>> +#define STM32_RTC_DR_YEAR GENMASK(23, 16)
>> +
>> +/* STM32_RTC_CR bit fields */
>> +#define STM32_RTC_CR_FMT BIT(6)
>> +#define STM32_RTC_CR_ALRAE BIT(8)
>> +#define STM32_RTC_CR_ALRAIE BIT(12)
>> +
>> +/* STM32_RTC_ISR bit fields */
>> +#define STM32_RTC_ISR_ALRAWF BIT(0)
>> +#define STM32_RTC_ISR_INITS BIT(4)
>> +#define STM32_RTC_ISR_RSF BIT(5)
>> +#define STM32_RTC_ISR_INITF BIT(6)
>> +#define STM32_RTC_ISR_INIT BIT(7)
>> +#define STM32_RTC_ISR_ALRAF BIT(8)
>> +
>> +/* STM32_RTC_PRER bit fields */
>> +#define STM32_RTC_PRER_PRED_S_SHIFT 0
>> +#define STM32_RTC_PRER_PRED_S GENMASK(14, 0)
>> +#define STM32_RTC_PRER_PRED_A_SHIFT 16
>> +#define STM32_RTC_PRER_PRED_A GENMASK(22, 16)
>> +
>> +/* STM32_RTC_ALRMAR and STM32_RTC_ALRMBR bit fields */
>> +#define STM32_RTC_ALRMXR_SEC_SHIFT 0
>> +#define STM32_RTC_ALRMXR_SEC GENMASK(6, 0)
>> +#define STM32_RTC_ALRMXR_SEC_MASK BIT(7)
>> +#define STM32_RTC_ALRMXR_MIN_SHIFT 8
>> +#define STM32_RTC_ALRMXR_MIN GENMASK(14, 8)
>> +#define STM32_RTC_ALRMXR_MIN_MASK BIT(15)
>> +#define STM32_RTC_ALRMXR_HOUR_SHIFT 16
>> +#define STM32_RTC_ALRMXR_HOUR GENMASK(21, 16)
>> +#define STM32_RTC_ALRMXR_PM BIT(22)
>> +#define STM32_RTC_ALRMXR_HOUR_MASK BIT(23)
>> +#define STM32_RTC_ALRMXR_DATE_SHIFT 24
>> +#define STM32_RTC_ALRMXR_DATE GENMASK(29, 24)
>> +#define STM32_RTC_ALRMXR_WDSEL BIT(30)
>> +#define STM32_RTC_ALRMXR_WDAY_SHIFT 24
>> +#define STM32_RTC_ALRMXR_WDAY GENMASK(27, 24)
>> +#define STM32_RTC_ALRMXR_DATE_MASK BIT(31)
>> +
>> +/* STM32_RTC_WPR key constants */
>> +#define RTC_WPR_1ST_KEY 0xCA
>> +#define RTC_WPR_2ND_KEY 0x53
>> +#define RTC_WPR_WRONG_KEY 0xFF
>> +
>> +/*
>> + * RTC registers are protected agains parasitic write access.
>> + * PWR_CR_DBP bit must be set to enable write access to RTC registers.
>> + */
>> +/* STM32_PWR_CR */
>> +#define PWR_CR 0x00
>> +/* STM32_PWR_CR bit field */
>> +#define PWR_CR_DBP BIT(8)
>> +
>> +static struct regmap *dbp;
>> +
>> +struct stm32_rtc {
>> + struct rtc_device *rtc_dev;
>> + void __iomem *base;
>> + struct clk *pclk;
>> + struct clk *ck_rtc;
>> + unsigned int clksrc;
>> + spinlock_t lock; /* Protects registers accesses */
>> + int irq_alarm;
>> + struct regmap *pwrcr;
>> +};
>> +
>> +static inline unsigned int stm32_rtc_readl(struct stm32_rtc *rtc,
>> + unsigned int offset)
>> +{
>> + return readl_relaxed(rtc->base + offset);
>> +}
>> +
>> +static inline void stm32_rtc_writel(struct stm32_rtc *rtc,
>> + unsigned int offset, unsigned int value)
>> +{
>> + writel_relaxed(value, rtc->base + offset);
>> +}
>
> I'm not sure wrapping the readl/writel_relaxed function does anything special
> other than simply redirecting the reader to another section of the code.
During development phase, it is useful to add debug traces but you're right, this can be remove.
>
>> +
>> +static void stm32_rtc_wpr_unlock(struct stm32_rtc *rtc)
>> +{
>> +// if (dbp)
>> +// regmap_update_bits(dbp, PWR_CR, PWR_CR_DBP, PWR_CR_DBP);
>
> Did checkpatch let you get away with this? What did you intend to do here?
Hum, as surprising as it may seem, checkpatch didn't complained about these comments! But anyway, this has to be removed, it was a tentative to enable/disable backup domain write protection any time we have to write in a protected RTC register, but it is not functionnal. I have commented this just to keep it in mind and forget to remove it before sending.
>
>> +
>> + stm32_rtc_writel(rtc, STM32_RTC_WPR, RTC_WPR_1ST_KEY);
>> + stm32_rtc_writel(rtc, STM32_RTC_WPR, RTC_WPR_2ND_KEY);
>> +}
>> +
>> +static void stm32_rtc_wpr_lock(struct stm32_rtc *rtc)
>> +{
>> + stm32_rtc_writel(rtc, STM32_RTC_WPR, RTC_WPR_WRONG_KEY);
>> +
>> +// if (dbp)
>> +// regmap_update_bits(dbp, PWR_CR, PWR_CR_DBP, ~PWR_CR_DBP);
>> +}
>> +
>> +static int stm32_rtc_enter_init_mode(struct stm32_rtc *rtc)
>> +{
>> + unsigned int isr = stm32_rtc_readl(rtc, STM32_RTC_ISR);
>> +
>> + if (!(isr & STM32_RTC_ISR_INITF)) {
>> + isr |= STM32_RTC_ISR_INIT;
>> + stm32_rtc_writel(rtc, STM32_RTC_ISR, isr);
>> +
>> + return readl_relaxed_poll_timeout_atomic(
>> + rtc->base + STM32_RTC_ISR,
>> + isr, (isr & STM32_RTC_ISR_INITF),
>> + 10, 100000);
>
> When using hard coded numerics please add comments that explains the reason
> behind the selected values.
Sure. It takes around 2 RTCCLK clock cycles to enter in initialization phase mode. So it depends on the frequency of the ck_rtc parent clock.
Either I keep parent clock frequency and compute the exact timeout, or I use the "best and worst cases": slowest RTCCLK frequency is 32kHz, so it can take up to 62us, highest RTCCLK frequency should be 1MHz, so it can take only 2us. Polling every 10us with a timeout of 100ms seemed reasonable and be a good compromise.
>
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static void stm32_rtc_exit_init_mode(struct stm32_rtc *rtc)
>> +{
>> + unsigned int isr = stm32_rtc_readl(rtc, STM32_RTC_ISR);
>> +
>> + isr &= ~STM32_RTC_ISR_INIT;
>> + stm32_rtc_writel(rtc, STM32_RTC_ISR, isr);
>> +}
>> +
>> +static int stm32_rtc_wait_sync(struct stm32_rtc *rtc)
>> +{
>> + unsigned int isr;
>> +
>> + isr = stm32_rtc_readl(rtc, STM32_RTC_ISR);
>> +
>> + isr &= ~STM32_RTC_ISR_RSF;
>> + stm32_rtc_writel(rtc, STM32_RTC_ISR, isr);
>> +
>> + /* Wait the registers to be synchronised */
>> + return readl_relaxed_poll_timeout_atomic(rtc->base + STM32_RTC_ISR,
>> + isr,
>> + (isr & STM32_RTC_ISR_RSF),
>> + 10, 100000);
>
> Shouldn't the break condition be !((isr & STM32_RTC_ISR_RSF) ? If not this
> probably deserve a better comment.
RSF bit is set by hardware each time the calendar registers are synchronized (it takes up to 2 RTCCLK). So the break condition is correct: we poll until RSF flag is set or timeout is reached.
>
>> +}
>> +
>> +static irqreturn_t stm32_rtc_alarm_irq(int irq, void *dev_id)
>> +{
>> + struct stm32_rtc *rtc = (struct stm32_rtc *)dev_id;
>> + unsigned long irqflags, events = 0;
>> + unsigned int isr, cr;
>> +
>> + spin_lock_irqsave(&rtc->lock, irqflags);
>> +
>> + isr = stm32_rtc_readl(rtc, STM32_RTC_ISR);
>> + cr = stm32_rtc_readl(rtc, STM32_RTC_CR);
>> +
>> + if ((isr & STM32_RTC_ISR_ALRAF) &&
>> + (cr & STM32_RTC_CR_ALRAIE)) {
>> + /* Alarm A flag - Alarm interrupt */
>> + events |= RTC_IRQF | RTC_AF;
>> + isr &= ~STM32_RTC_ISR_ALRAF;
>> + }
>> +
>> + /* Clear event irqflags, otherwise new events won't be received */
>> + stm32_rtc_writel(rtc, STM32_RTC_ISR, isr);
>> +
>> + spin_unlock_irqrestore(&rtc->lock, irqflags);
>> +
>> + if (events) {
>> + dev_info(&rtc->rtc_dev->dev, "Alarm occurred\n");
>> +
>> + /* Pass event to the kernel */
>> + rtc_update_irq(rtc->rtc_dev, 1, events);
>> + return IRQ_HANDLED;
>> + } else {
>> + return IRQ_NONE;
>> + }
>> +}
>> +
>> +/* Convert rtc_time structure from bin to bcd format */
>> +static void tm2bcd(struct rtc_time *tm)
>> +{
>> + tm->tm_sec = bin2bcd(tm->tm_sec);
>> + tm->tm_min = bin2bcd(tm->tm_min);
>> + tm->tm_hour = bin2bcd(tm->tm_hour);
>> +
>> + tm->tm_mday = bin2bcd(tm->tm_mday);
>> + tm->tm_mon = bin2bcd(tm->tm_mon + 1);
>> + tm->tm_year = bin2bcd(tm->tm_year - 100);
>> + /*
>> + * Number of days since Sunday
>> + * - on kernel side, 0=Sunday...6=Saturday
>> + * - on rtc side, 0=invalid,1=Monday...7=Sunday
>> + */
>> + tm->tm_wday = (!tm->tm_wday) ? 7 : tm->tm_wday;
>> +}
>> +
>> +/* Convert rtc_time structure from bcd to bin format */
>> +static void bcd2tm(struct rtc_time *tm)
>> +{
>> + tm->tm_sec = bcd2bin(tm->tm_sec);
>> + tm->tm_min = bcd2bin(tm->tm_min);
>> + tm->tm_hour = bcd2bin(tm->tm_hour);
>> +
>> + tm->tm_mday = bcd2bin(tm->tm_mday);
>> + tm->tm_mon = bcd2bin(tm->tm_mon) - 1;
>> + tm->tm_year = bcd2bin(tm->tm_year) + 100;
>> + /*
>> + * Number of days since Sunday
>> + * - on kernel side, 0=Sunday...6=Saturday
>> + * - on rtc side, 0=invalid,1=Monday...7=Sunday
>> + */
>> + tm->tm_wday %= 7;
>> +}
>> +
>> +static int stm32_rtc_read_time(struct device *dev, struct rtc_time *tm)
>> +{
>> + struct stm32_rtc *rtc = dev_get_drvdata(dev);
>> + unsigned int tr, dr;
>> + unsigned long irqflags;
>> +
>> + spin_lock_irqsave(&rtc->lock, irqflags);
>> +
>> + /* Time and Date in BCD format */
>> + tr = stm32_rtc_readl(rtc, STM32_RTC_TR);
>> + dr = stm32_rtc_readl(rtc, STM32_RTC_DR);
>> +
>> + spin_unlock_irqrestore(&rtc->lock, irqflags);
>> +
>> + tm->tm_sec = (tr & STM32_RTC_TR_SEC) >> STM32_RTC_TR_SEC_SHIFT;
>> + tm->tm_min = (tr & STM32_RTC_TR_MIN) >> STM32_RTC_TR_MIN_SHIFT;
>> + tm->tm_hour = (tr & STM32_RTC_TR_HOUR) >> STM32_RTC_TR_HOUR_SHIFT;
>> +
>> + tm->tm_mday = (dr & STM32_RTC_DR_DATE) >> STM32_RTC_DR_DATE_SHIFT;
>> + tm->tm_mon = (dr & STM32_RTC_DR_MONTH) >> STM32_RTC_DR_MONTH_SHIFT;
>> + tm->tm_year = (dr & STM32_RTC_DR_YEAR) >> STM32_RTC_DR_YEAR_SHIFT;
>> + tm->tm_wday = (dr & STM32_RTC_DR_WDAY) >> STM32_RTC_DR_WDAY_SHIFT;
>> +
>> + /* We don't report tm_yday and tm_isdst */
>> +
>> + bcd2tm(tm);
>> +
>> + if (rtc_valid_tm(tm) < 0) {
>> + dev_err(dev, "%s: rtc_time is not valid.\n", __func__);
>> + return -EINVAL;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static int stm32_rtc_set_time(struct device *dev, struct rtc_time *tm)
>> +{
>> + struct stm32_rtc *rtc = dev_get_drvdata(dev);
>> + unsigned int tr, dr;
>> + unsigned long irqflags;
>> + int ret = 0;
>> +
>> + if (rtc_valid_tm(tm) < 0) {
>> + dev_err(dev, "%s: rtc_time is not valid.\n", __func__);
>> + return -EINVAL;
>> + }
>> +
>> + tm2bcd(tm);
>> +
>> + /* Time in BCD format */
>> + tr = ((tm->tm_sec << STM32_RTC_TR_SEC_SHIFT) & STM32_RTC_TR_SEC) |
>> + ((tm->tm_min << STM32_RTC_TR_MIN_SHIFT) & STM32_RTC_TR_MIN) |
>> + ((tm->tm_hour << STM32_RTC_TR_HOUR_SHIFT) & STM32_RTC_TR_HOUR);
>> +
>> + /* Date in BCD format */
>> + dr = ((tm->tm_mday << STM32_RTC_DR_DATE_SHIFT) & STM32_RTC_DR_DATE) |
>> + ((tm->tm_mon << STM32_RTC_DR_MONTH_SHIFT) & STM32_RTC_DR_MONTH) |
>> + ((tm->tm_year << STM32_RTC_DR_YEAR_SHIFT) & STM32_RTC_DR_YEAR) |
>> + ((tm->tm_wday << STM32_RTC_DR_WDAY_SHIFT) & STM32_RTC_DR_WDAY);
>> +
>> + spin_lock_irqsave(&rtc->lock, irqflags);
>> +
>> + stm32_rtc_wpr_unlock(rtc);
>> +
>> + ret = stm32_rtc_enter_init_mode(rtc);
>> + if (ret) {
>> + dev_err(dev, "Can't enter in init mode. Set time aborted.\n");
>> + goto end;
>> + }
>> +
>> + stm32_rtc_writel(rtc, STM32_RTC_TR, tr);
>> + stm32_rtc_writel(rtc, STM32_RTC_DR, dr);
>> +
>> + stm32_rtc_exit_init_mode(rtc);
>> +
>> + ret = stm32_rtc_wait_sync(rtc);
>> +end:
>> + stm32_rtc_wpr_lock(rtc);
>> +
>> + spin_unlock_irqrestore(&rtc->lock, irqflags);
>> +
>> + return ret;
>> +}
>> +
>> +static int stm32_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
>> +{
>> + struct stm32_rtc *rtc = dev_get_drvdata(dev);
>> + struct rtc_time *tm = &alrm->time;
>> + unsigned int alrmar, cr, isr;
>> + unsigned long irqflags;
>> +
>> + spin_lock_irqsave(&rtc->lock, irqflags);
>> +
>> + alrmar = stm32_rtc_readl(rtc, STM32_RTC_ALRMAR);
>> + cr = stm32_rtc_readl(rtc, STM32_RTC_CR);
>> + isr = stm32_rtc_readl(rtc, STM32_RTC_ISR);
>> +
>> + spin_unlock_irqrestore(&rtc->lock, irqflags);
>> +
>> + if (alrmar & STM32_RTC_ALRMXR_DATE_MASK) {
>> + /*
>> + * Date/day don't care in Alarm comparison so alarm triggers
>> + * every day
>> + */
>> + tm->tm_mday = -1;
>> + tm->tm_wday = -1;
>> + } else {
>> + if (alrmar & STM32_RTC_ALRMXR_WDSEL) {
>> + /* Alarm is set to a day of week */
>> + tm->tm_mday = -1;
>> + tm->tm_wday = (alrmar & STM32_RTC_ALRMXR_WDAY) >>
>> + STM32_RTC_ALRMXR_WDAY_SHIFT;
>> + tm->tm_wday %= 7;
>> + } else {
>> + /* Alarm is set to a day of month */
>> + tm->tm_wday = -1;
>> + tm->tm_mday = (alrmar & STM32_RTC_ALRMXR_DATE) >>
>> + STM32_RTC_ALRMXR_DATE_SHIFT;
>> + }
>> + }
>> +
>> + if (alrmar & STM32_RTC_ALRMXR_HOUR_MASK) {
>> + /* Hours don't care in Alarm comparison */
>> + tm->tm_hour = -1;
>> + } else {
>> + tm->tm_hour = (alrmar & STM32_RTC_ALRMXR_HOUR) >>
>> + STM32_RTC_ALRMXR_HOUR_SHIFT;
>> + if (alrmar & STM32_RTC_ALRMXR_PM)
>> + tm->tm_hour += 12;
>> + }
>> +
>> + if (alrmar & STM32_RTC_ALRMXR_MIN_MASK) {
>> + /* Minutes don't care in Alarm comparison */
>> + tm->tm_min = -1;
>> + } else {
>> + tm->tm_min = (alrmar & STM32_RTC_ALRMXR_MIN) >>
>> + STM32_RTC_ALRMXR_MIN_SHIFT;
>> + }
>> +
>> + if (alrmar & STM32_RTC_ALRMXR_SEC_MASK) {
>> + /* Seconds don't care in Alarm comparison */
>> + tm->tm_sec = -1;
>> + } else {
>> + tm->tm_sec = (alrmar & STM32_RTC_ALRMXR_SEC) >>
>> + STM32_RTC_ALRMXR_SEC_SHIFT;
>> + }
>> +
>> + bcd2tm(tm);
>> +
>> + alrm->enabled = (cr & STM32_RTC_CR_ALRAE) ? 1 : 0;
>> + alrm->pending = (isr & STM32_RTC_ISR_ALRAF) ? 1 : 0;
>> +
>> + return 0;
>> +}
>> +
>> +static int stm32_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
>> +{
>> + struct stm32_rtc *rtc = dev_get_drvdata(dev);
>> + unsigned long irqflags;
>> + unsigned int isr, cr;
>> +
>> + cr = stm32_rtc_readl(rtc, STM32_RTC_CR);
>
> Is the STM32_RTC_CR garanteed to be valid, i.e updated atomically? If not this
> should probably be below the spinlock.
You're right.
>
>> +
>> + spin_lock_irqsave(&rtc->lock, irqflags);
>> +
>> + stm32_rtc_wpr_unlock(rtc);
>> +
>> + /* We expose Alarm A to the kernel */
>> + if (enabled)
>> + cr |= (STM32_RTC_CR_ALRAIE | STM32_RTC_CR_ALRAE);
>> + else
>> + cr &= ~(STM32_RTC_CR_ALRAIE | STM32_RTC_CR_ALRAE);
>> + stm32_rtc_writel(rtc, STM32_RTC_CR, cr);
>> +
>> + /* Clear event irqflags, otherwise new events won't be received */
>> + isr = stm32_rtc_readl(rtc, STM32_RTC_ISR);
>> + isr &= ~STM32_RTC_ISR_ALRAF;
>> + stm32_rtc_writel(rtc, STM32_RTC_ISR, isr);
>> +
>> + stm32_rtc_wpr_lock(rtc);
>> +
>> + spin_unlock_irqrestore(&rtc->lock, irqflags);
>> +
>> + return 0;
>> +}
>> +
>> +static int stm32_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
>> +{
>> + struct stm32_rtc *rtc = dev_get_drvdata(dev);
>> + struct rtc_time *tm = &alrm->time;
>> + unsigned long irqflags;
>> + unsigned int cr, isr, alrmar;
>> + int ret = 0;
>> +
>> + if (rtc_valid_tm(tm)) {
>> + dev_err(dev, "Alarm time not valid.\n");
>> + return -EINVAL;
>> + }
>> +
>> + tm2bcd(tm);
>> +
>> + spin_lock_irqsave(&rtc->lock, irqflags);
>> +
>> + stm32_rtc_wpr_unlock(rtc);
>> +
>> + /* Disable Alarm */
>> + cr = stm32_rtc_readl(rtc, STM32_RTC_CR);
>> + cr &= ~STM32_RTC_CR_ALRAE;
>> + stm32_rtc_writel(rtc, STM32_RTC_CR, cr);
>> +
>> + /* Poll Alarm write flag to be sure that Alarm update is allowed */
>> + ret = readl_relaxed_poll_timeout_atomic(rtc->base + STM32_RTC_ISR,
>> + isr,
>> + (isr & STM32_RTC_ISR_ALRAWF),
>> + 10, 100);
>> +
>> + if (ret) {
>> + dev_err(dev, "Alarm update not allowed\n");
>> + goto end;
>> + }
>> +
>> + alrmar = 0;
>> +
>> + if (tm->tm_mday < 0 && tm->tm_wday < 0) {
>> + /*
>> + * Date/day don't care in Alarm comparison so alarm triggers
>> + * every day
>> + */
>> + alrmar |= STM32_RTC_ALRMXR_DATE_MASK;
>> + } else {
>> + if (tm->tm_mday > 0) {
>> + /* Date is selected (ignoring wday) */
>> + alrmar |= (tm->tm_mday << STM32_RTC_ALRMXR_DATE_SHIFT) &
>> + STM32_RTC_ALRMXR_DATE;
>> + } else {
>> + /* Day of week is selected */
>> + int wday = (tm->tm_wday == 0) ? 7 : tm->tm_wday;
>> +
>> + alrmar |= STM32_RTC_ALRMXR_WDSEL;
>> + alrmar |= (wday << STM32_RTC_ALRMXR_WDAY_SHIFT) &
>> + STM32_RTC_ALRMXR_WDAY;
>> + }
>> + }
>> +
>> + if (tm->tm_hour < 0) {
>> + /* Hours don't care in Alarm comparison */
>> + alrmar |= STM32_RTC_ALRMXR_HOUR_MASK;
>> + } else {
>> + /* 24-hour format */
>> + alrmar &= ~STM32_RTC_ALRMXR_PM;
>> + alrmar |= (tm->tm_hour << STM32_RTC_ALRMXR_HOUR_SHIFT) &
>> + STM32_RTC_ALRMXR_HOUR;
>> + }
>> +
>> + if (tm->tm_min < 0) {
>> + /* Minutes don't care in Alarm comparison */
>> + alrmar |= STM32_RTC_ALRMXR_MIN_MASK;
>> + } else {
>> + alrmar |= (tm->tm_min << STM32_RTC_ALRMXR_MIN_SHIFT) &
>> + STM32_RTC_ALRMXR_MIN;
>> + }
>> +
>> + if (tm->tm_sec < 0) {
>> + /* Seconds don't care in Alarm comparison */
>> + alrmar |= STM32_RTC_ALRMXR_SEC_MASK;
>> + } else {
>> + alrmar |= (tm->tm_sec << STM32_RTC_ALRMXR_SEC_SHIFT) &
>> + STM32_RTC_ALRMXR_SEC;
>> + }
>> +
>> + /* Write to Alarm register */
>> + stm32_rtc_writel(rtc, STM32_RTC_ALRMAR, alrmar);
>> +
>> + if (alrm->enabled)
>> + stm32_rtc_alarm_irq_enable(dev, 1);
>> + else
>> + stm32_rtc_alarm_irq_enable(dev, 0);
>> +
>> +end:
>> + stm32_rtc_wpr_lock(rtc);
>> +
>> + spin_unlock_irqrestore(&rtc->lock, irqflags);
>> +
>> + return ret;
>> +}
>> +
>> +static const struct rtc_class_ops stm32_rtc_ops = {
>> + .read_time = stm32_rtc_read_time,
>> + .set_time = stm32_rtc_set_time,
>> + .read_alarm = stm32_rtc_read_alarm,
>> + .set_alarm = stm32_rtc_set_alarm,
>> + .alarm_irq_enable = stm32_rtc_alarm_irq_enable,
>> +};
>> +
>> +#ifdef CONFIG_OF
>> +static const struct of_device_id stm32_rtc_of_match[] = {
>> + { .compatible = "st,stm32-rtc" },
>> + {}
>> +};
>> +MODULE_DEVICE_TABLE(of, stm32_rtc_of_match);
>> +#endif
>> +
>> +static int stm32_rtc_init(struct platform_device *pdev,
>> + struct stm32_rtc *rtc)
>> +{
>> + unsigned int prer, pred_a, pred_s, pred_a_max, pred_s_max, cr;
>> + unsigned int rate;
>> + unsigned long irqflags;
>> + int ret = 0;
>> +
>> + rate = clk_get_rate(rtc->ck_rtc);
>> +
>> + /* Find prediv_a and prediv_s to obtain the 1Hz calendar clock */
>> + pred_a_max = STM32_RTC_PRER_PRED_A >> STM32_RTC_PRER_PRED_A_SHIFT;
>> + pred_s_max = STM32_RTC_PRER_PRED_S >> STM32_RTC_PRER_PRED_S_SHIFT;
>> +
>> + for (pred_a = pred_a_max; pred_a >= 0; pred_a--) {
>> + pred_s = (rate / (pred_a + 1)) - 1;
>> +
>> + if (((pred_s + 1) * (pred_a + 1)) == rate)
>> + break;
>> + }
>> +
>> + /*
>> + * Can't find a 1Hz, so give priority to RTC power consumption
>> + * by choosing the higher possible value for prediv_a
>> + */
>> + if ((pred_s > pred_s_max) || (pred_a > pred_a_max)) {
>> + pred_a = pred_a_max;
>> + pred_s = (rate / (pred_a + 1)) - 1;
>> +
>> + dev_warn(&pdev->dev, "ck_rtc is %s\n",
>> + (rate - ((pred_a + 1) * (pred_s + 1)) < 0) ?
>> + "fast" : "slow");
>> + }
>> +
>> + spin_lock_irqsave(&rtc->lock, irqflags);
>> +
>> + stm32_rtc_wpr_unlock(rtc);
>> +
>> + ret = stm32_rtc_enter_init_mode(rtc);
>> + if (ret) {
>> + dev_err(&pdev->dev,
>> + "Can't enter in init mode. Prescaler config failed.\n");
>> + goto end;
>> + }
>> +
>> + prer = (pred_s << STM32_RTC_PRER_PRED_S_SHIFT) & STM32_RTC_PRER_PRED_S;
>> + stm32_rtc_writel(rtc, STM32_RTC_PRER, prer);
>> + prer |= (pred_a << STM32_RTC_PRER_PRED_A_SHIFT) & STM32_RTC_PRER_PRED_A;
>> + stm32_rtc_writel(rtc, STM32_RTC_PRER, prer);
>> +
>> + /* Force 24h time format */
>> + cr = stm32_rtc_readl(rtc, STM32_RTC_CR);
>> + cr &= ~STM32_RTC_CR_FMT;
>> + stm32_rtc_writel(rtc, STM32_RTC_CR, cr);
>> +
>> + stm32_rtc_exit_init_mode(rtc);
>> +
>> + ret = stm32_rtc_wait_sync(rtc);
>> +
>> + if (stm32_rtc_readl(rtc, STM32_RTC_ISR) & STM32_RTC_ISR_INITS)
>> + dev_warn(&pdev->dev, "Date/Time must be initialized\n");
>> +end:
>> + stm32_rtc_wpr_lock(rtc);
>> +
>> + spin_unlock_irqrestore(&rtc->lock, irqflags);
>> +
>> + return ret;
>> +}
>> +
>> +static int stm32_rtc_probe(struct platform_device *pdev)
>> +{
>> + struct stm32_rtc *rtc;
>> + struct resource *res;
>> + int ret;
>> +
>> + rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
>> + if (!rtc)
>> + return -ENOMEM;
>> +
>> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>
> The value of 'res' should be checked before using it.
res is checked in devm_ioremap_resource just below :
if (!res || resource_type(res) != IORESOURCE_MEM) {
dev_err(dev, "invalid resource\n");
return IOMEM_ERR_PTR(-EINVAL);
}
That's why it is not checked here.
>
>> + rtc->base = devm_ioremap_resource(&pdev->dev, res);
>> + if (IS_ERR(rtc->base))
>> + return PTR_ERR(rtc->base);
>> +
>> + dbp = syscon_regmap_lookup_by_phandle(pdev->dev.of_node, "st,syscfg");
>> + if (IS_ERR(dbp)) {
>> + dev_err(&pdev->dev, "no st,syscfg\n");
>> + return PTR_ERR(dbp);
>> + }
>> +
>> + spin_lock_init(&rtc->lock);
>> +
>> + rtc->ck_rtc = devm_clk_get(&pdev->dev, "ck_rtc");
>> + if (IS_ERR(rtc->ck_rtc)) {
>> + dev_err(&pdev->dev, "no ck_rtc clock");
>> + return PTR_ERR(rtc->ck_rtc);
>> + }
>> +
>> + ret = clk_prepare_enable(rtc->ck_rtc);
>> + if (ret)
>> + return ret;
>> +
>> + if (dbp)
>> + regmap_update_bits(dbp, PWR_CR, PWR_CR_DBP, PWR_CR_DBP);
>
> The code above exits if there is a problem with the dbp, there is no point in
> checking again.
You're right.
>
>> +
>> + ret = stm32_rtc_init(pdev, rtc);
>> + if (ret)
>> + goto err;
>> +
>> + rtc->irq_alarm = platform_get_irq_byname(pdev, "alarm");
>> + if (rtc->irq_alarm <= 0) {
>> + dev_err(&pdev->dev, "no alarm irq\n");
>> + ret = -ENOENT;
>> + goto err;
>> + }
>> +
>> + platform_set_drvdata(pdev, rtc);
>> +
>> + device_init_wakeup(&pdev->dev, true);
>
> What happens if device_init_wakeup() returns an error?
It means that RTC won't be able to wake up the board with RTC alarm. I can add a warning for the user in this case ?
>
>> +
>> + rtc->rtc_dev = devm_rtc_device_register(&pdev->dev, pdev->name,
>> + &stm32_rtc_ops, THIS_MODULE);
>> + if (IS_ERR(rtc->rtc_dev)) {
>> + ret = PTR_ERR(rtc->rtc_dev);
>> + dev_err(&pdev->dev, "rtc device registration failed, err=%d\n",
>> + ret);
>> + goto err;
>> + }
>> +
>> + /* Handle RTC alarm interrupts */
>> + ret = devm_request_irq(&pdev->dev, rtc->irq_alarm,
>> + stm32_rtc_alarm_irq, IRQF_TRIGGER_RISING,
>> + dev_name(&rtc->rtc_dev->dev), rtc);
>> + if (ret) {
>> + dev_err(&pdev->dev, "IRQ%d (alarm interrupt) already claimed\n",
>> + rtc->irq_alarm);
>> + goto err;
>> + }
>> +
>> + return 0;
>> +err:
>> + clk_disable_unprepare(rtc->ck_rtc);
>> +
>> + if (dbp)
>> + regmap_update_bits(dbp, PWR_CR, PWR_CR_DBP, ~PWR_CR_DBP);
>
> Same comment as above.
OK.
>
>> +
>> + device_init_wakeup(&pdev->dev, false);
>> +
>> + return ret;
>> +}
>> +
>> +static int __exit stm32_rtc_remove(struct platform_device *pdev)
>> +{
>> + struct stm32_rtc *rtc = platform_get_drvdata(pdev);
>> + unsigned int cr;
>> +
>> + /* Disable interrupts */
>> + stm32_rtc_wpr_unlock(rtc);
>> + cr = stm32_rtc_readl(rtc, STM32_RTC_CR);
>> + cr &= ~STM32_RTC_CR_ALRAIE;
>> + stm32_rtc_writel(rtc, STM32_RTC_CR, cr);
>> + stm32_rtc_wpr_lock(rtc);
>> +
>> + clk_disable_unprepare(rtc->ck_rtc);
>> +
>> + /* Enable backup domain write protection */
>> + if (dbp)
>> + regmap_update_bits(dbp, PWR_CR, PWR_CR_DBP, ~PWR_CR_DBP);
>> +
>> + device_init_wakeup(&pdev->dev, false);
>> +
>> + return 0;
>> +}
>> +
>> +#ifdef CONFIG_PM_SLEEP
>> +static int stm32_rtc_suspend(struct device *dev)
>> +{
>> + struct stm32_rtc *rtc = dev_get_drvdata(dev);
>> +
>> + if (device_may_wakeup(dev))
>> + return enable_irq_wake(rtc->irq_alarm);
>> +
>> + return 0;
>> +}
>> +
>> +static int stm32_rtc_resume(struct device *dev)
>> +{
>> + struct stm32_rtc *rtc = dev_get_drvdata(dev);
>> + int ret = 0;
>> +
>> + ret = stm32_rtc_wait_sync(rtc);
>> + if (ret < 0)
>> + return ret;
>> +
>> + if (device_may_wakeup(dev))
>> + return disable_irq_wake(rtc->irq_alarm);
>> +
>> + return ret;
>> +}
>> +#endif
>> +
>> +static SIMPLE_DEV_PM_OPS(stm32_rtc_pm_ops,
>> + stm32_rtc_suspend, stm32_rtc_resume);
>> +
>> +static struct platform_driver stm32_rtc_driver = {
>> + .probe = stm32_rtc_probe,
>> + .remove = stm32_rtc_remove,
>> + .driver = {
>> + .name = DRIVER_NAME,
>> + .pm = &stm32_rtc_pm_ops,
>> + .of_match_table = stm32_rtc_of_match,
>> + },
>> +};
>> +
>> +module_platform_driver(stm32_rtc_driver);
>> +
>> +MODULE_ALIAS("platform:" DRIVER_NAME);
>> +MODULE_AUTHOR("Amelie Delaunay <amelie.delaunay@xxxxxx>");
>> +MODULE_DESCRIPTION("STMicroelectronics STM32 Real Time Clock driver");
>> +MODULE_LICENSE("GPL v2");
>> --
>> 1.9.1
>>

Best regards,
Amelie

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