1、了解rtc_device结构体
1)、打开“include/linux/rtc.h”
rtc_class_ops是需要用户根据所使用的RTC设备编写的,其结构体如下:
struct rtc_class_ops {
int (*ioctl)(struct device *, unsigned int, unsigned long);/*函数指针ioctl*/
int (*read_time)(struct device *, struct rtc_time *);/*函数指针read_time*/
int (*set_time)(struct device *, struct rtc_time *);/*函数指针set_time*/
int (*read_alarm)(struct device *, struct rtc_wkalrm *);
/*函数指针read_alarm*/
int (*set_alarm)(struct device *, struct rtc_wkalrm *);
/*函数指针set_alarm*/
int (*proc)(struct device *, struct seq_file *);/*函数指针proc*/
int (*alarm_irq_enable)(struct device *, unsigned int enabled);
/*函数指针alarm_irq_enable*/
int (*read_offset)(struct device *, long *offset);/*函数指针read_offset*/
int (*set_offset)(struct device *, long offset);/*函数指针set_offset*/
};
struct rtc_device {
struct device dev; /*设备*/
struct module *owner;
int id; /*设备ID号*/
const struct rtc_class_ops *ops;/*RTC设备最底层操作函数*/
struct mutex ops_lock;
struct cdev char_dev;/*字符设备*/
unsigned long flags;
unsigned long irq_data;
spinlock_t irq_lock;
wait_queue_head_t irq_queue;
struct fasync_struct *async_queue;
int irq_freq;
int max_user_freq;
struct timerqueue_head timerqueue;
struct rtc_timer aie_timer;
struct rtc_timer uie_rtctimer;
struct hrtimer pie_timer; /* sub second exp, so needs hrtimer */
int pie_enabled;
struct work_struct irqwork;
/* Some hardware can't support UIE mode */
int uie_unsupported;
/* Number of nsec it takes to set the RTC clock. This influences when
* the set ops are called. An offset:
* - of 0.5 s will call RTC set for wall clock time 10.0 s at 9.5 s
* - of 1.5 s will call RTC set for wall clock time 10.0 s at 8.5 s
* - of -0.5 s will call RTC set for wall clock time 10.0 s at 10.5 s
*/
long set_offset_nsec;
bool registered;
/* Old ABI support */
bool nvram_old_abi;
struct bin_attribute *nvram;
time64_t range_min;
timeu64_t range_max;
time64_t start_secs;
time64_t offset_secs;
bool set_start_time;
#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
struct work_struct uie_task;
struct timer_list uie_timer;
/* Those fields are protected by rtc->irq_lock */
unsigned int oldsecs;
unsigned int uie_irq_active:1;
unsigned int stop_uie_polling:1;
unsigned int uie_task_active:1;
unsigned int uie_timer_active:1;
#endif
};
2)、打开“drivers/rtc/class.c”
/*注册RTC类设备
* devm_rtc_device_register - resource managed rtc_device_register()
* @dev: 要注册的设备，the device to register
* @name: 设备名字,the name of the device (unused)
* @ops: 底层驱动函数集，the rtc operations structure
* @owner: 驱动模块拥有者，the module owner
*返回值:注册成功的话就返回rtcdevice，4错误的话会返回一个负值
* @return a struct rtc on success, or an ERR_PTR on error
*
* Managed rtc_device_register(). The rtc_device returned from this function
* are automatically freed on driver detach.
* This function is deprecated, use devm_rtc_allocate_device and
* rtc_register_device instead
*/
struct rtc_device *devm_rtc_device_register(struct device *dev,
const char *name,
const struct rtc_class_ops *ops,
struct module *owner)
{
struct rtc_device *rtc;
int err;
rtc = devm_rtc_allocate_device(dev);
if (IS_ERR(rtc))
return rtc;
rtc->ops = ops;
err = __rtc_register_device(owner, rtc);
if (err)
return ERR_PTR(err);
return rtc;
}
struct rtc_device *rtc_device_register(const char *name, struct device *dev, const struct rtc_class_ops *ops, struct module *owner);//rtc_device_register()和devm_rtc_device_register()功能相同;
/**
*卸载RTC驱动时,删除先前注册的RTC类设备
* rtc_device_unregister - removes the previously registered RTC class device
*
* @rtc: the RTC class device to destroy
*/
static void rtc_device_unregister(struct rtc_device *rtc)
{
mutex_lock(&rtc->ops_lock);
/*
* Remove innards of this RTC, then disable it, before
* letting any rtc_class_open() users access it again
*/
rtc_proc_del_device(rtc);
cdev_device_del(&rtc->char_dev, &rtc->dev);
rtc->ops = NULL;
mutex_unlock(&rtc->ops_lock);
put_device(&rtc->dev);
}
int __rtc_register_device(struct module *owner, struct rtc_device *rtc)
{
struct rtc_wkalrm alrm;
int err;
if (!rtc->ops) {
dev_dbg(&rtc->dev, "no ops set\n");
return -EINVAL;
}
rtc->owner = owner;
rtc_device_get_offset(rtc);
/* Check to see if there is an ALARM already set in hw */
err = __rtc_read_alarm(rtc, &alrm);
if (!err && !rtc_valid_tm(&alrm.time))
rtc_initialize_alarm(rtc, &alrm);
rtc_dev_prepare(rtc);
err = cdev_device_add(&rtc->char_dev, &rtc->dev);
if (err)
dev_warn(rtc->dev.parent, "failed to add char device %d:%d\n",
MAJOR(rtc->dev.devt), rtc->id);
else
dev_dbg(rtc->dev.parent, "char device (%d:%d)\n",
MAJOR(rtc->dev.devt), rtc->id);
rtc_proc_add_device(rtc);
rtc->registered = true;
dev_info(rtc->dev.parent, "registered as %s\n",
dev_name(&rtc->dev));
return 0;
}
/**卸载RTC驱动时,删除先前注册的RTC类设备;
* rtc_device_unregister - removes the previously registered RTC class device
*
* @rtc: the RTC class device to destroy
*/
static void rtc_device_unregister(struct rtc_device *rtc)
{
mutex_lock(&rtc->ops_lock);/* 上锁 */
/*
* Remove innards of this RTC, then disable it, before
* letting any rtc_class_open() users access it again
*/
rtc_proc_del_device(rtc);
cdev_device_del(&rtc->char_dev, &rtc->dev);
rtc->ops = NULL;
mutex_unlock(&rtc->ops_lock);/* 解锁,释放互斥锁 */
put_device(&rtc->dev);
}
devm_rtc_device_unregister()和rtc_device_unregister(struct rtc_device *rtc)功能相同;
3)、打开“include/linux/rtc.h”
/*
* For these RTC methods the device parameter is the physical device
* on whatever bus holds the hardware (I2C, Platform, SPI, etc), which
* was passed to rtc_device_register(). Its driver_data normally holds
* device state, including the rtc_device pointer for the RTC.
*
* Most of these methods are called with rtc_device.ops_lock held,
* through the rtc_*(struct rtc_device *, ...) calls.
*
* The (current) exceptions are mostly filesystem hooks:
* - the proc() hook for procfs
* - non-ioctl() chardev hooks: open(), release()
*
* REVISIT those periodic irq calls *do* have ops_lock when they're
* issued through ioctl() ...
rtc_class_ops是需要用户根据所使用的RTC设备编写的,其结构体如下:
*/
struct rtc_class_ops {
int (*ioctl)(struct device *, unsigned int, unsigned long);/*函数指针ioctl*/
int (*read_time)(struct device *, struct rtc_time *);/*函数指针read_time*/
int (*set_time)(struct device *, struct rtc_time *);/*函数指针set_time*/
int (*read_alarm)(struct device *, struct rtc_wkalrm *);/*函数指针read_alarm*/
int (*set_alarm)(struct device *, struct rtc_wkalrm *);/*函数指针set_alarm*/
int (*proc)(struct device *, struct seq_file *);/*函数指针proc*/
int (*alarm_irq_enable)(struct device *, unsigned int enabled);/*函数指针alarm_irq_enable*/
int (*read_offset)(struct device *, long *offset);/*函数指针read_offset*/
int (*set_offset)(struct device *, long offset);/*函数指针set_offset*/
};
打开“/usr/include/linux/rtc.h”
struct rtc_time {
int tm_sec;
int tm_min;
int tm_hour;
int tm_mday;
int tm_mon;
int tm_year;
int tm_wday;
int tm_yday;
int tm_isdst;
};
4)、打开“drivers/rtc/dev.c”
/* 设备操作函数结构体 */
/*声明file_operations结构变量rtc_dev_fops，它是指向设备的操作函数集合变量*/
static const struct file_operations rtc_dev_fops = {
.owner = THIS_MODULE,
/*表示该文件的操作结构体所属的模块是当前的模块，即这个模块属于内核*/
.llseek = no_llseek,
.read = rtc_dev_read,
.poll = rtc_dev_poll,
.unlocked_ioctl = rtc_dev_ioctl,
.open = rtc_dev_open,
.release = rtc_dev_release,
.fasync = rtc_dev_fasync,
};
static long rtc_dev_ioctl(struct file *file,
unsigned int cmd, unsigned long arg)
{
int err = 0;
struct rtc_device *rtc = file->private_data;
const struct rtc_class_ops *ops = rtc->ops;
struct rtc_time tm;
struct rtc_wkalrm alarm;
void __user *uarg = (void __user *)arg;
err = mutex_lock_interruptible(&rtc->ops_lock);
if (err)
return err;
/* check that the calling task has appropriate permissions
* for certain ioctls. doing this check here is useful
* to avoid duplicate code in each driver.
*/
switch (cmd) {
case RTC_EPOCH_SET:
case RTC_SET_TIME:
if (!capable(CAP_SYS_TIME))
err = -EACCES;
break;
case RTC_IRQP_SET:
if (arg > rtc->max_user_freq && !capable(CAP_SYS_RESOURCE))
err = -EACCES;
break;
case RTC_PIE_ON:
if (rtc->irq_freq > rtc->max_user_freq &&
!capable(CAP_SYS_RESOURCE))
err = -EACCES;
break;
}
if (err)
goto done;
/*
* Drivers *SHOULD NOT* provide ioctl implementations
* for these requests. Instead, provide methods to
* support the following code, so that the RTC's main
* features are accessible without using ioctls.
*
* RTC and alarm times will be in UTC, by preference,
* but dual-booting with MS-Windows implies RTCs must
* use the local wall clock time.
*/
switch (cmd) {
case RTC_ALM_READ:
mutex_unlock(&rtc->ops_lock);/* 解锁,释放互斥锁 */
err = rtc_read_alarm(rtc, &alarm);
if (err < 0)
return err;
if (copy_to_user(uarg, &alarm.time, sizeof(tm)))
err = -EFAULT;
return err;
case RTC_ALM_SET:
mutex_unlock(&rtc->ops_lock);/* 解锁,释放互斥锁 */
if (copy_from_user(&alarm.time, uarg, sizeof(tm)))
return -EFAULT;
alarm.enabled = 0;
alarm.pending = 0;
alarm.time.tm_wday = -1;
alarm.time.tm_yday = -1;
alarm.time.tm_isdst = -1;
/* RTC_ALM_SET alarms may be up to 24 hours in the future.
* Rather than expecting every RTC to implement "don't care"
* for day/month/year fields, just force the alarm to have
* the right values for those fields.
*
* RTC_WKALM_SET should be used instead. Not only does it
* eliminate the need for a separate RTC_AIE_ON call, it
* doesn't have the "alarm 23:59:59 in the future" race.
*
* NOTE: some legacy code may have used invalid fields as
* wildcards, exposing hardware "periodic alarm" capabilities.
* Not supported here.
*/
{
time64_t now, then;
err = rtc_read_time(rtc, &tm);
if (err < 0)
return err;
now = rtc_tm_to_time64(&tm);
alarm.time.tm_mday = tm.tm_mday;
alarm.time.tm_mon = tm.tm_mon;
alarm.time.tm_year = tm.tm_year;
err = rtc_valid_tm(&alarm.time);
if (err < 0)
return err;
then = rtc_tm_to_time64(&alarm.time);
/* alarm may need to wrap into tomorrow */
if (then < now) {
rtc_time64_to_tm(now + 24 * 60 * 60, &tm);
alarm.time.tm_mday = tm.tm_mday;
alarm.time.tm_mon = tm.tm_mon;
alarm.time.tm_year = tm.tm_year;
}
}
return rtc_set_alarm(rtc, &alarm);
case RTC_RD_TIME: /*读时间命令*/
mutex_unlock(&rtc->ops_lock);/* 解锁,释放互斥锁 */
err = rtc_read_time(rtc, &tm);
/*获取当前RTC时钟,rtc_read_time()会调用__rtc_read_time()*/
if (err < 0)
return err;
if (copy_to_user(uarg, &tm, sizeof(tm)))
err = -EFAULT;
return err;
case RTC_SET_TIME: /*设置时间命令*/
mutex_unlock(&rtc->ops_lock);/* 解锁,释放互斥锁 */
if (copy_from_user(&tm, uarg, sizeof(tm)))
return -EFAULT;
return rtc_set_time(rtc, &tm);/*设置时间*/
case RTC_PIE_ON:
err = rtc_irq_set_state(rtc, 1);
break;
case RTC_PIE_OFF:
err = rtc_irq_set_state(rtc, 0);
break;
case RTC_AIE_ON:
mutex_unlock(&rtc->ops_lock);/* 解锁,释放互斥锁 */
return rtc_alarm_irq_enable(rtc, 1);
case RTC_AIE_OFF:
mutex_unlock(&rtc->ops_lock);/* 解锁,释放互斥锁 */
return rtc_alarm_irq_enable(rtc, 0);
case RTC_UIE_ON:
mutex_unlock(&rtc->ops_lock);/* 解锁,释放互斥锁 */
return rtc_update_irq_enable(rtc, 1);
case RTC_UIE_OFF:
mutex_unlock(&rtc->ops_lock);/* 解锁,释放互斥锁 */
return rtc_update_irq_enable(rtc, 0);
case RTC_IRQP_SET:
err = rtc_irq_set_freq(rtc, arg);
break;
case RTC_IRQP_READ:
err = put_user(rtc->irq_freq, (unsigned long __user *)uarg);
break;
case RTC_WKALM_SET:
mutex_unlock(&rtc->ops_lock);/* 解锁,释放互斥锁 */
if (copy_from_user(&alarm, uarg, sizeof(alarm)))
return -EFAULT;
return rtc_set_alarm(rtc, &alarm);
case RTC_WKALM_RD:
mutex_unlock(&rtc->ops_lock);/* 解锁,释放互斥锁 */
err = rtc_read_alarm(rtc, &alarm);
if (err < 0)
return err;
if (copy_to_user(uarg, &alarm, sizeof(alarm)))
err = -EFAULT;
return err;
default:
/* Finally try the driver's ioctl interface */
if (ops->ioctl) {
err = ops->ioctl(rtc->dev.parent, cmd, arg);
if (err == -ENOIOCTLCMD)
err = -ENOTTY;
} else {
err = -ENOTTY;
}
break;
}
done:
mutex_unlock(&rtc->ops_lock);/* 解锁,释放互斥锁 */
return err;
}
5)、打开“/linux-5.4.31/drivers/rtc/interface.c”
static int __rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm)
{
int err;
if (!rtc->ops) {
err = -ENODEV;
} else if (!rtc->ops->read_time) {
err = -EINVAL;
} else {
memset(tm, 0, sizeof(struct rtc_time));
err = rtc->ops->read_time(rtc->dev.parent, tm);
if (err < 0) {
dev_dbg(&rtc->dev, "read_time: fail to read: %d\n",
err);
return err;
}
rtc_add_offset(rtc, tm);
err = rtc_valid_tm(tm);
if (err < 0)
dev_dbg(&rtc->dev, "read_time: rtc_time isn't valid\n");
}
return err;
}
int rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm)
{
int err;
err = mutex_lock_interruptible(&rtc->ops_lock);
if (err)
return err;
err = __rtc_read_time(rtc, tm);
mutex_unlock(&rtc->ops_lock);/* 解锁,释放互斥锁 */
trace_rtc_read_time(rtc_tm_to_time64(tm), err);
return err;
}
6)、打开“/linux-5.4.31/drivers/rtc/rtc-stm32.c”
static const struct of_device_id stm32_rtc_of_match[] = {
{ .compatible = "st,stm32-rtc", .data = &stm32_rtc_data },
{ .compatible = "st,stm32h7-rtc", .data = &stm32h7_rtc_data },
{ .compatible = "st,stm32mp1-rtc", .data = &stm32mp1_data },
/*"st,stm32mp1-rtc"在设备树中*/
{ /*这是一个空元素,在编写of_device_id时最后一个元素一定要为空*/
/* Sentinel */
}
};
/*标准的platform驱动框架*/
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,
},
};
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,
};
2、修改设备树
1)、打开“stm32mp151.dtsi”找到“rtc”，内容如下：
rtc: rtc@5c004000 {
compatible = "st,stm32mp1-rtc";
reg = <0x5c004000 0x400>;
clocks = <&scmi0_clk CK_SCMI0_RTCAPB>,
<&scmi0_clk CK_SCMI0_RTC>;
clock-names = "pclk", "rtc_ck";
interrupts-extended = <&exti 19 IRQ_TYPE_LEVEL_HIGH>;
status = "disabled";
};
2)、打开“stm32mp157d-atk.dts”,添加内容如下(注意：不是在根节点“/”下添加)：
&rtc {
status = "okay";
};
3、“drivers/rtc/rtc-stm32.c”程序如下：
#include <linux/bcd.h>
#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/errno.h>
#include <linux/iopoll.h>
#include <linux/ioport.h>
#include <linux/mfd/syscon.h>
#include <linux/module.h>//使能stm32_rtc_init()
#include <linux/of_device.h>
#include <linux/pm_wakeirq.h>
#include <linux/regmap.h>
#include <linux/rtc.h>
#include <dt-bindings/rtc/rtc-stm32.h>
#define DRIVER_NAME "stm32_rtc"
/* 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(12, 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)
#define STM32_RTC_CR_COSEL BIT(19)
#define STM32_RTC_CR_OSEL_SHIFT 21
#define STM32_RTC_CR_OSEL GENMASK(22, 21)
#define STM32_RTC_CR_COE BIT(23)
#define STM32_RTC_CR_TAMPOE BIT(26)
#define STM32_RTC_CR_OUT2EN BIT(31)
/* STM32_RTC_ISR/STM32_RTC_ICSR 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_SR/_SCR bit fields */
#define STM32_RTC_SR_ALRA BIT(0)
/* STM32_RTC_CFGR bit fields */
#define STM32_RTC_CFGR_OUT2_RMP BIT(0)
#define STM32_RTC_CFGR_LSCOEN_OUT1 1
#define STM32_RTC_CFGR_LSCOEN_OUT2_RMP 2
/* STM32_RTC_VERR bit fields */
#define STM32_RTC_VERR_MINREV_SHIFT 0
#define STM32_RTC_VERR_MINREV GENMASK(3, 0)
#define STM32_RTC_VERR_MAJREV_SHIFT 4
#define STM32_RTC_VERR_MAJREV GENMASK(7, 4)
/* STM32_RTC_WPR key constants */
#define RTC_WPR_1ST_KEY 0xCA
#define RTC_WPR_2ND_KEY 0x53
#define RTC_WPR_WRONG_KEY 0xFF
/* Max STM32 RTC register offset is 0x3FC */
#define UNDEF_REG 0xFFFF
struct stm32_rtc;//声明stm32_rtc结构类型
struct stm32_rtc_registers {
u16 tr;
u16 dr;
u16 cr;
u16 isr;/*RTC_ICSR寄存器*/
u16 prer;
u16 alrmar;
u16 wpr;
u16 sr;
u16 scr;
u16 cfgr;
u16 verr;
};
struct stm32_rtc_events {
u32 alra;
};
struct stm32_rtc_data {
const struct stm32_rtc_registers regs;
const struct stm32_rtc_events events;
void (*clear_events)(struct stm32_rtc *rtc, unsigned int flags);
bool has_pclk;
bool need_dbp;
bool has_lsco;
};
struct stm32_rtc {
struct rtc_device *rtc_dev;
void __iomem *base;
struct regmap *dbp;
unsigned int dbp_reg;
unsigned int dbp_mask;
struct clk *pclk;
struct clk *rtc_ck;
const struct stm32_rtc_data *data;
int irq_alarm;
int lsco;
struct clk *clk_lsco;
};
/*
* -------------------------------------------------------------------------
* | TAMPOE | OSEL[1:0] | COE | OUT2EN | RTC_OUT1 | RTC_OUT2 |
* | | | | | | or RTC_OUT2_RMP |
* |-------------------------------------------------------------------------|
* | 0 | 00 | 0 | 0 or 1 | - | - |
* |--------|-----------|-----|--------|------------------|------------------|
* | 0 | 00 | 1 | 0 | CALIB | - |
* |--------|-----------|-----|--------|------------------|------------------|
* | 0 or 1 | !=00 | 0 | 0 | TAMPALRM | - |
* |--------|-----------|-----|--------|------------------|------------------|
* | 0 | 00 | 1 | 1 | - | CALIB |
* |--------|-----------|-----|--------|------------------|------------------|
* | 0 or 1 | !=00 | 0 | 1 | - | TAMPALRM |
* |--------|-----------|-----|--------|------------------|------------------|
* | 0 or 1 | !=00 | 1 | 1 | TAMPALRM | CALIB |
* -------------------------------------------------------------------------
*/
static int stm32_rtc_clk_lsco_check_availability(struct stm32_rtc *rtc)
{
struct stm32_rtc_registers regs = rtc->data->regs;
unsigned int cr = readl_relaxed(rtc->base + regs.cr);
/*读取STM32MP1的RTC_CR寄存器的值*/
unsigned int cfgr = readl_relaxed(rtc->base + regs.cfgr);
/*读取STM32MP1的RTC_CFGR寄存器的值*/
unsigned int calib = STM32_RTC_CR_COE;
unsigned int tampalrm = STM32_RTC_CR_TAMPOE | STM32_RTC_CR_OSEL;
switch (rtc->lsco) {
case RTC_OUT1:
if ((!(cr & STM32_RTC_CR_OUT2EN) &&
((cr & calib) || cr & tampalrm)) ||
((cr & calib) && (cr & tampalrm)))
return -EBUSY;
break;
case RTC_OUT2_RMP:
if ((cr & STM32_RTC_CR_OUT2EN) &&
(cfgr & STM32_RTC_CFGR_OUT2_RMP) &&
((cr & calib) || (cr & tampalrm)))
return -EBUSY;
break;
default:
return -EINVAL;
}
if (clk_get_rate(rtc->rtc_ck) != 32768)
/*获得rtc->rtc_ck时钟源的当前时钟频率(HZ)*/
return -ERANGE;
return 0;
}
static int stm32_rtc_clk_lsco_register(struct platform_device *pdev)
{
struct stm32_rtc *rtc = platform_get_drvdata(pdev);
struct stm32_rtc_registers regs = rtc->data->regs;
u8 lscoen;
int ret;
ret = stm32_rtc_clk_lsco_check_availability(rtc);
if (ret)
return ret;
lscoen = (rtc->lsco == RTC_OUT1) ? STM32_RTC_CFGR_LSCOEN_OUT1 :
STM32_RTC_CFGR_LSCOEN_OUT2_RMP;
rtc->clk_lsco = clk_register_gate(&pdev->dev, "rtc_lsco",
__clk_get_name(rtc->rtc_ck),
CLK_IGNORE_UNUSED | CLK_IS_CRITICAL,
rtc->base + regs.cfgr, lscoen,
0, NULL);
if (IS_ERR(rtc->clk_lsco))
return PTR_ERR(rtc->clk_lsco);
of_clk_add_provider(pdev->dev.of_node,
of_clk_src_simple_get, rtc->clk_lsco);
return 0;
}
/*“RTC寄存器“解锁，允许写入*/
static void stm32_rtc_wpr_unlock(struct stm32_rtc *rtc)
{
const struct stm32_rtc_registers *regs = &rtc->data->regs;
writel_relaxed(RTC_WPR_1ST_KEY, rtc->base + regs->wpr);
writel_relaxed(RTC_WPR_2ND_KEY, rtc->base + regs->wpr);
/*
解锁步骤：
1. Write 0xCA into the RTC_WPR register.
2. Write 0x53 into the RTC_WPR register.
*/
}
/*写错值，会重新激活“RTC寄存器“写保护，不允许写RTC寄存器；
Writing a wrong key reactivates the write protection.
*/
static void stm32_rtc_wpr_lock(struct stm32_rtc *rtc)
{
const struct stm32_rtc_registers *regs = &rtc->data->regs;
writel_relaxed(RTC_WPR_WRONG_KEY, rtc->base + regs->wpr);
/*将0xFF写入“RTC写保护寄存器RTC_WPR“*/
}
//函数功能：令RTC进入初始化模式
static int stm32_rtc_enter_init_mode(struct stm32_rtc *rtc)
{
const struct stm32_rtc_registers *regs = &rtc->data->regs;
unsigned int isr = readl_relaxed(rtc->base + regs->isr);
/*读“RTC_ICSR寄存器“*/
if (!(isr & STM32_RTC_ISR_INITF)) {
isr |= STM32_RTC_ISR_INIT;
/*准备将“RTC_ICSR寄存器“的bit7置1*/
/*Initialization mode used to program time and date register
(RTC_TR and RTC_DR), and prescaler register (RTC_PRER).*/
writel_relaxed(isr, rtc->base + regs->isr);
/*将isr的值写入“RTC_ICSR寄存器“*/
/*
* It takes around 2 rtc_ck clock cycles to enter in
* initialization phase mode (and have INITF flag set). As
* slowest rtc_ck frequency may be 32kHz and highest should be
* 1MHz, we poll every 10 us with a timeout of 100ms.
*/
return readl_relaxed_poll_timeout_atomic(
rtc->base + regs->isr,
isr, (isr & STM32_RTC_ISR_INITF),
10, 100000);
/*每10us轮询一次“RTC_ICSR寄存器“的bit7是否置1；
直到从“Free running mode”进入“Initialization mode“
*/
}
return 0;
}
//函数功能：令RTC进入“自由运行模式“
static void stm32_rtc_exit_init_mode(struct stm32_rtc *rtc)
{
const struct stm32_rtc_registers *regs = &rtc->data->regs;
unsigned int isr = readl_relaxed(rtc->base + regs->isr);
/*读“RTC_ICSR寄存器“*/
isr &= ~STM32_RTC_ISR_INIT;
/*准备将“RTC_ICSR寄存器“的bit7置0，
令RTC从“Initialization mode“进入“Free running mode”*/
writel_relaxed(isr, rtc->base + regs->isr);
/*将isr的值写入“RTC_ICSR寄存器“*/
}
//函数功能：令“日历影子寄存器“同步
static int stm32_rtc_wait_sync(struct stm32_rtc *rtc)
{
const struct stm32_rtc_registers *regs = &rtc->data->regs;
unsigned int isr = readl_relaxed(rtc->base + regs->isr);
/*读“RTC_ICSR寄存器“*/
isr &= ~STM32_RTC_ISR_RSF;
/*准备将“RTC_ICSR寄存器“的bit5置0，准备令“日历影子寄存器“不同步；
“RTC_ICSR寄存器“的bit5=1,表示“Calendar shadow registers synchronized“
*/
writel_relaxed(isr, rtc->base + regs->isr);
/*将isr的值写入“RTC_ICSR寄存器“*/
/*
* Wait for RSF to be set to ensure the calendar registers are
* synchronised, it takes around 2 rtc_ck clock cycles
*/
return readl_relaxed_poll_timeout_atomic(rtc->base + regs->isr,
isr,
(isr & STM32_RTC_ISR_RSF),
10, 100000);
/*每10us轮询一次“RTC_ICSR寄存器“的bit5是否置1；
直到“日历影子寄存器“同步
*/
}
/*将flags写入RTC_SCR寄存器(RTC status clear register)*/
static void stm32_rtc_clear_event_flags(struct stm32_rtc *rtc,
unsigned int flags)
{
rtc->data->clear_events(rtc, flags);
/*将flags写入RTC_SCR寄存器(RTC status clear register)*/
}
/*RTC的“Alarm A”中断服务函数*/
static irqreturn_t stm32_rtc_alarm_irq(int irq, void *dev_id)
{
struct stm32_rtc *rtc = (struct stm32_rtc *)dev_id;
const struct stm32_rtc_registers *regs = &rtc->data->regs;
const struct stm32_rtc_events *evts = &rtc->data->events;
unsigned int status, cr;
mutex_lock(&rtc->rtc_dev->ops_lock);/* 上锁 */
status = readl_relaxed(rtc->base + regs->sr);/*读“RTC_SR寄存器“*/
cr = readl_relaxed(rtc->base + regs->cr);/*读“RTC_CR寄存器“*/
if ((status & evts->alra) &&
(cr & STM32_RTC_CR_ALRAIE)) {
/* Alarm A flag - Alarm interrupt */
dev_dbg(&rtc->rtc_dev->dev, "Alarm occurred\n");
/*将事件传递给内核，Pass event to the kernel */
rtc_update_irq(rtc->rtc_dev, 1, RTC_IRQF | RTC_AF);
/* Clear event flags, otherwise new events won't be received */
stm32_rtc_clear_event_flags(rtc, evts->alra);
/*将evts->alra写入RTC_SCR寄存器(RTC status clear register);
Clear alarm A flag;
*/
}
mutex_unlock(&rtc->rtc_dev->ops_lock);/* 解锁,释放互斥锁 */
return IRQ_HANDLED;
}
/* Convert rtc_time structure from bin to bcd format */
/*函数功能：将rtc_time结构转换为BCD格式*/
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 */
/*函数功能：将BCD格式转换为rtc_time结构*/
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;
}
//函数功能：读取RTC时间和日期，保存到tm中
static int stm32_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
struct stm32_rtc *rtc = dev_get_drvdata(dev);
const struct stm32_rtc_registers *regs = &rtc->data->regs;
unsigned int tr, dr;
/* Time and Date in BCD format */
tr = readl_relaxed(rtc->base + regs->tr);/*读取STM32MP1的RTC_TR时间寄存器的值*/
dr = readl_relaxed(rtc->base + regs->dr);/*读取STM32MP1的RTC_DR日期寄存器的值*/
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);/*将BCD格式转换为rtc_time格式*/
return 0;
}
//函数功能：将tm中的时间和日期写入RTC_TR时间寄存器和RTC_DR日期寄存器
static int stm32_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
struct stm32_rtc *rtc = dev_get_drvdata(dev);
const struct stm32_rtc_registers *regs = &rtc->data->regs;
unsigned int tr, dr;
int ret = 0;
tm2bcd(tm);/*将rtc_time结构转换为BCD格式*/
/* 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);
stm32_rtc_wpr_unlock(rtc);/*“RTC寄存器“解锁，允许写入*/
ret = stm32_rtc_enter_init_mode(rtc);/*令RTC进入初始化模式*/
if (ret) {
dev_err(dev, "Can't enter in init mode. Set time aborted.\n");
goto end;
}
writel_relaxed(tr, rtc->base + regs->tr);/*tr写入RTC_TR时间寄存器*/
writel_relaxed(dr, rtc->base + regs->dr);/*dr写入RTC_DR日期寄存器*/
stm32_rtc_exit_init_mode(rtc);/*令RTC进入“自由运行模式“*/
ret = stm32_rtc_wait_sync(rtc);/*令“日历影子寄存器“同步*/
end:
stm32_rtc_wpr_lock(rtc);/*写错值，会重新激活“RTC寄存器“写保护，不允许写RTC寄存器*/
return ret;
}
//函数功能：读RTC报警时间，保存到alrm结构中
static int stm32_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
struct stm32_rtc *rtc = dev_get_drvdata(dev);
const struct stm32_rtc_registers *regs = &rtc->data->regs;
const struct stm32_rtc_events *evts = &rtc->data->events;
struct rtc_time *tm = &alrm->time;
unsigned int alrmar, cr, status;
alrmar = readl_relaxed(rtc->base + regs->alrmar);
/*读取STM32MP1的RTC_ALRMAR寄存器的值*/
cr = readl_relaxed(rtc->base + regs->cr);
/*读取STM32MP1的RTC_CR寄存器的值*/
status = readl_relaxed(rtc->base + regs->sr);
/*读取STM32MP1的RTC_CS寄存器的值*/
if (alrmar & STM32_RTC_ALRMXR_DATE_MASK) {
/*日期/天不用匹配，即每天触发一次报警
* Date/day doesn't matter in Alarm comparison so alarm
* triggers every day
*/
tm->tm_mday = -1;
tm->tm_wday = -1;
} else {//日期/天匹配，才会报警
if (alrmar & STM32_RTC_ALRMXR_WDSEL) {
/*在星期几触发一次报警；
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;
/*将RTC_ALRMAR中的DU[3:0]保存到tm->tm_wday*/
tm->tm_wday %= 7;/*得到星期几*/
} else {
/* 在某天触发报警
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;
/*将RTC_ALRMAR中的DU[3:0]保存到tm->tm_wday*/
}
}
if (alrmar & STM32_RTC_ALRMXR_HOUR_MASK) {
/* 不要求小时报警
Hours don't matter in Alarm comparison */
tm->tm_hour = -1;
} else {/*要求小时报警*/
tm->tm_hour = (alrmar & STM32_RTC_ALRMXR_HOUR) >>
STM32_RTC_ALRMXR_HOUR_SHIFT;
/*将RTC_ALRMAR中的HU[3:0]保存到tm->tm_hour*/
if (alrmar & STM32_RTC_ALRMXR_PM)
tm->tm_hour += 12;
}
if (alrmar & STM32_RTC_ALRMXR_MIN_MASK) {
/* 不要求分钟报警
Minutes don't matter in Alarm comparison */
tm->tm_min = -1;
} else {/*要求分钟报警*/
tm->tm_min = (alrmar & STM32_RTC_ALRMXR_MIN) >>
STM32_RTC_ALRMXR_MIN_SHIFT;
/*将RTC_ALRMAR中的MNT[2:0]和MNU[3:0]保存到tm->tm_min*/
}
if (alrmar & STM32_RTC_ALRMXR_SEC_MASK) {
/* 不要求妙报警
Seconds don't matter in Alarm comparison */
tm->tm_sec = -1;
} else {/*要求妙报警*/
tm->tm_sec = (alrmar & STM32_RTC_ALRMXR_SEC) >>
STM32_RTC_ALRMXR_SEC_SHIFT;
/*将RTC_ALRMAR中的ST[2:0]和SU[3:0]保存到tm->tm_sec*/
}
bcd2tm(tm);
alrm->enabled = (cr & STM32_RTC_CR_ALRAE) ? 1 : 0;
/*如果“Alarm A enable”，则返回1；
如果“Alarm A disabled”，则返回0；
*/
alrm->pending = (status & evts->alra) ? 1 : 0;
/*如果“Alarm A标志“建立，则返回1；
如果“Alarm A标志“没有建立，则返回0；
*/
return 0;
}
/*函数功能：
enabled=1，设置使能“ALARM A“和使能“ALARM A“报警时能产生中断；
enabled=0，设置不使能“ALARM A“和不使能“ALARM A“报警时能产生中断；
*/
static int stm32_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
struct stm32_rtc *rtc = dev_get_drvdata(dev);
const struct stm32_rtc_registers *regs = &rtc->data->regs;
const struct stm32_rtc_events *evts = &rtc->data->events;
unsigned int cr;
cr = readl_relaxed(rtc->base + regs->cr);
/*读取STM32MP1的RTC_CR寄存器的值*/
stm32_rtc_wpr_unlock(rtc);/*“RTC寄存器“解锁，允许写入*/
/* We expose Alarm A to the kernel */
if (enabled)
cr |= (STM32_RTC_CR_ALRAIE | STM32_RTC_CR_ALRAE);
/*准备将RTC_CR寄存器的bit12置1，使能ALARM A报警中断*/
/*准备将RTC_CR寄存器的bit8置1，使能ALARM A*/
else
cr &= ~(STM32_RTC_CR_ALRAIE | STM32_RTC_CR_ALRAE);
/*准备将RTC_CR寄存器的bit12置0，不使能ALARM A报警中断*/
/*准备将RTC_CR寄存器的bit8置0，不使能ALARM A*/
writel_relaxed(cr, rtc->base + regs->cr);/*cr写入RTC_CR寄存器*/
/* Clear event flags, otherwise new events won't be received */
stm32_rtc_clear_event_flags(rtc, evts->alra);
/*将evts->alra写入RTC_SCR寄存器(RTC status clear register)*/
stm32_rtc_wpr_lock(rtc);/*写错值，会重新激活“RTC寄存器“写保护，不允许写RTC寄存器*/
return 0;
}
//函数功能：返回0，表示设置的ALARM报警时间tm是有效的
static int stm32_rtc_valid_alrm(struct stm32_rtc *rtc, struct rtc_time *tm)
{
const struct stm32_rtc_registers *regs = &rtc->data->regs;
int cur_day, cur_mon, cur_year, cur_hour, cur_min, cur_sec;
unsigned int dr = readl_relaxed(rtc->base + regs->dr);
/*读取STM32MP1的RTC_DR日期寄存器的值*/
unsigned int tr = readl_relaxed(rtc->base + regs->tr);
/*读取STM32MP1的RTC_TR时间寄存器的值*/
cur_day = (dr & STM32_RTC_DR_DATE) >> STM32_RTC_DR_DATE_SHIFT;
cur_mon = (dr & STM32_RTC_DR_MONTH) >> STM32_RTC_DR_MONTH_SHIFT;
cur_year = (dr & STM32_RTC_DR_YEAR) >> STM32_RTC_DR_YEAR_SHIFT;
cur_sec = (tr & STM32_RTC_TR_SEC) >> STM32_RTC_TR_SEC_SHIFT;
cur_min = (tr & STM32_RTC_TR_MIN) >> STM32_RTC_TR_MIN_SHIFT;
cur_hour = (tr & STM32_RTC_TR_HOUR) >> STM32_RTC_TR_HOUR_SHIFT;
/*
* Assuming current date is M-D-Y H:M:S.
* RTC alarm can't be set on a specific month and year.
* So the valid alarm range is:
* M-D-Y H:M:S < alarm <= (M+1)-D-Y H:M:S
* with a specific case for December...
*/
if ((((tm->tm_year > cur_year) &&
(tm->tm_mon == 0x1) && (cur_mon == 0x12)) ||
((tm->tm_year == cur_year) &&
(tm->tm_mon <= cur_mon + 1))) &&
((tm->tm_mday > cur_day) ||
((tm->tm_mday == cur_day) &&
((tm->tm_hour > cur_hour) ||
((tm->tm_hour == cur_hour) && (tm->tm_min > cur_min)) ||
((tm->tm_hour == cur_hour) && (tm->tm_min == cur_min) &&
(tm->tm_sec >= cur_sec))))))
return 0;
return -EINVAL;
}
//函数功能：设置“ALARM A报警时间“，报警时间保存在alrm中
static int stm32_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
struct stm32_rtc *rtc = dev_get_drvdata(dev);
const struct stm32_rtc_registers *regs = &rtc->data->regs;
struct rtc_time *tm = &alrm->time;
unsigned int cr, isr, alrmar;
int ret = 0;
tm2bcd(tm);/*将rtc_time结构转换为BCD格式*/
/*
* RTC alarm can't be set on a specific date, unless this date is
* up to the same day of month next month.
*/
if (stm32_rtc_valid_alrm(rtc, tm) < 0) {
/*stm32_rtc_valid_alrm()返回0，表示设置的ALARM报警时间tm是有效的*/
dev_err(dev, "Alarm can be set only on upcoming month.\n");
return -EINVAL;
}
alrmar = 0;
/* tm_year and tm_mon are not used because not supported by RTC */
alrmar |= (tm->tm_mday << STM32_RTC_ALRMXR_DATE_SHIFT) &
STM32_RTC_ALRMXR_DATE;
/* 24-hour format */
alrmar &= ~STM32_RTC_ALRMXR_PM;
alrmar |= (tm->tm_hour << STM32_RTC_ALRMXR_HOUR_SHIFT) &
STM32_RTC_ALRMXR_HOUR;
alrmar |= (tm->tm_min << STM32_RTC_ALRMXR_MIN_SHIFT) &
STM32_RTC_ALRMXR_MIN;
alrmar |= (tm->tm_sec << STM32_RTC_ALRMXR_SEC_SHIFT) &
STM32_RTC_ALRMXR_SEC;
stm32_rtc_wpr_unlock(rtc);/*“RTC寄存器“解锁，允许写入*/
/* Disable Alarm */
cr = readl_relaxed(rtc->base + regs->cr);/*读取STM32MP1的RTC_CR寄存器的值*/
cr &= ~STM32_RTC_CR_ALRAE;/*准备将RTC_CR寄存器的bit8置0，不使能ALARM A*/
writel_relaxed(cr, rtc->base + regs->cr);/*cr写入RTC_CR寄存器*/
/*
* Poll Alarm write flag to be sure that Alarm update is allowed: it
* takes around 2 rtc_ck clock cycles
*/
ret = readl_relaxed_poll_timeout_atomic(rtc->base + regs->isr,
isr,
(isr & STM32_RTC_ISR_ALRAWF),
10, 100000);
/*每10us轮询一次“RTC_ICSR寄存器“的bit0是否置1；
直到建立“Alarm A写标志“，才可以设置报警时间；
*/
if (ret) {
dev_err(dev, "Alarm update not allowed\n");
goto end;
}
/* Write to Alarm register */
writel_relaxed(alrmar, rtc->base + regs->alrmar);
/*将alrmar的值写入STM32MP1的RTC_ALRMAR寄存器*/
stm32_rtc_alarm_irq_enable(dev, alrm->enabled);
/*
enabled=1，设置使能“ALARM A“和使能“ALARM A“报警时能产生中断；
enabled=0，设置不使能“ALARM A“和不使能“ALARM A“报警时能产生中断；
*/
end:
stm32_rtc_wpr_lock(rtc);/*写错值，会重新激活“RTC寄存器“写保护，不允许写RTC寄存器*/
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,
/*给函数指针赋值，使用stm32_rtc_read_alarm()读RTC报警时间*/
.set_alarm = stm32_rtc_set_alarm,
/*给函数指针赋值，使用stm32_rtc_set_alarm()设置“ALARM A报警时间“*/
.alarm_irq_enable = stm32_rtc_alarm_irq_enable,
/*给函数指针赋值，使用stm32_rtc_alarm_irq_enable(enabled),
enabled=1，设置使能“ALARM A“和使能“ALARM A“报警时能产生中断；
enabled=0，设置不使能“ALARM A“和不使能“ALARM A“报警时能产生中断；
*/
};
/*清除“RTC initialization control and status register“中的事件标志位*/
/*
static void stm32_rtc_clear_events(struct stm32_rtc *rtc,
unsigned int flags)
{
const struct stm32_rtc_registers *regs = &rtc->data->regs;
//Flags are cleared by writing 0 in RTC_ISR
writel_relaxed(readl_relaxed(rtc->base + regs->isr) & ~flags,
rtc->base + regs->isr);
//readl_relaxed()读取STM32MP1的RTC_ICSR寄存器的值
//writel_relaxed()写STM32MP1的RTC_ICSR寄存器
//采用先读后写，清除“RTC initialization control and status register“中的事件标志位
}
*/
/*根据设备树，这个结构没用*/
/*
static const struct stm32_rtc_data stm32_rtc_data = {
.has_pclk = false,
.need_dbp = true,
.has_lsco = false,
.regs = {
.tr = 0x00,
.dr = 0x04,
.cr = 0x08,
.isr = 0x0C,
.prer = 0x10,
.alrmar = 0x1C,
.wpr = 0x24,
.sr = 0x0C, //set to ISR offset to ease alarm management
.scr = UNDEF_REG,
.cfgr = UNDEF_REG,
.verr = UNDEF_REG,
},
.events = {
.alra = STM32_RTC_ISR_ALRAF,
},
.clear_events = stm32_rtc_clear_events,
};
*/
/*根据设备树，这个结构没用*/
/*
static const struct stm32_rtc_data stm32h7_rtc_data = {
.has_pclk = true,
.need_dbp = true,
.has_lsco = false,
.regs = {
.tr = 0x00,
.dr = 0x04,
.cr = 0x08,
.isr = 0x0C,
.prer = 0x10,
.alrmar = 0x1C,
.wpr = 0x24,
.sr = 0x0C, //set to ISR offset to ease alarm management
.scr = UNDEF_REG,
.cfgr = UNDEF_REG,
.verr = UNDEF_REG,
},
.events = {
.alra = STM32_RTC_ISR_ALRAF,
},
.clear_events = stm32_rtc_clear_events,
};
*/
/*将flags写入RTC_SCR寄存器(RTC status clear register)*/
static void stm32mp1_rtc_clear_events(struct stm32_rtc *rtc,unsigned int flags)
{
struct stm32_rtc_registers regs = rtc->data->regs;
/* Flags are cleared by writing 1 in RTC_SCR */
writel_relaxed(flags, rtc->base + regs.scr);
/*将flags写入RTC_SCR寄存器*/
}
/*STM32MP157的RTC寄存器*/
static const struct stm32_rtc_data stm32mp1_data = {
.has_pclk = true,
.need_dbp = false,
.has_lsco = true,
.regs = {
.tr = 0x00,/*RTC_TR寄存器偏移地址*/
.dr = 0x04,/*RTC_DR寄存器偏移地址*/
.cr = 0x18,/*RTC_CR寄存器偏移地址*/
.isr = 0x0C, /*RTC_ICSR寄存器偏移地址,named RTC_ICSR on stm32mp1 */
.prer = 0x10,/*RTC_PRER寄存器偏移地址*/
.alrmar = 0x40,/*RTC_ALRMAR寄存器偏移地址*/
.wpr = 0x24,/*RTC_WPR寄存器偏移地址*/
.sr = 0x50,/*RTC_SR寄存器偏移地址*/
.scr = 0x5C,/*RTC_SCR寄存器偏移地址*/
.cfgr = 0x60,/*RTC_CFGR寄存器偏移地址*/
.verr = 0x3F4,/*RTC_VERR寄存器偏移地址*/
},
.events = {
.alra = STM32_RTC_SR_ALRA,/*将events.alra初始化为0*/
},
.clear_events = stm32mp1_rtc_clear_events,
/*将flags写入RTC_SCR寄存器(RTC status clear register)*/
};
/* 匹配列表 */
//驱动中的compatible属性要和和设备树中的compatible属性相匹配。
static const struct of_device_id stm32_rtc_of_match[] = {
/*{ .compatible = "st,stm32-rtc", .data = &stm32_rtc_data },
{ .compatible = "st,stm32h7-rtc", .data = &stm32h7_rtc_data },*/
{ .compatible = "st,stm32mp1-rtc", .data = &stm32mp1_data },
/*"st,stm32mp1-rtc"在设备树中*/
{ /*这是一个空元素,在编写of_device_id时最后一个元素一定要为空*/
/* Sentinel */
}
};
MODULE_DEVICE_TABLE(of, stm32_rtc_of_match);
/**初始化STM32MP1的rtc寄存器*/
static int stm32_rtc_init(struct platform_device *pdev,
struct stm32_rtc *rtc)
{
const struct stm32_rtc_registers *regs = &rtc->data->regs;
unsigned int prer, pred_a, pred_s, pred_a_max, pred_s_max, cr;
unsigned int rate;
int ret = 0;
rate = clk_get_rate(rtc->rtc_ck);/*获得rtc->rtc_ck时钟源的当前时钟频率(HZ)*/
/* 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 + 1 > 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, "rtc_ck is %s\n",
(rate < ((pred_a + 1) * (pred_s + 1))) ?
"fast" : "slow");
}
stm32_rtc_wpr_unlock(rtc);/*RTC写保护寄存器RTC_WPR*/
ret = stm32_rtc_enter_init_mode(rtc);/*令RTC进入初始化模式*/
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;
writel_relaxed(prer, rtc->base + regs->prer);
prer |= (pred_a << STM32_RTC_PRER_PRED_A_SHIFT) & STM32_RTC_PRER_PRED_A;
writel_relaxed(prer, rtc->base + regs->prer);
/* Force 24h time format */
cr = readl_relaxed(rtc->base + regs->cr);
cr &= ~STM32_RTC_CR_FMT;
writel_relaxed(cr, rtc->base + regs->cr);
stm32_rtc_exit_init_mode(rtc);/*令RTC进入“自由运行模式“*/
ret = stm32_rtc_wait_sync(rtc);/*令“日历影子寄存器“同步*/
end:
stm32_rtc_wpr_lock(rtc);/*写错值，会重新激活“RTC寄存器“写保护，不允许写RTC寄存器*/
return ret;
}
/*platform的probe函数为stm32_rtc_probe()*/
static int stm32_rtc_probe(struct platform_device *pdev)
{
struct stm32_rtc *rtc;
const struct stm32_rtc_registers *regs;
struct resource *res;
int ret;
rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
/*向内核申请一块内存，当设备驱动程序被卸载时，内存会被自动释放*/
if (!rtc)
return -ENOMEM;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
/*platform_get_resource()函数从设备树中获取到RTC外设寄存器基地址*/
rtc->base = devm_ioremap_resource(&pdev->dev, res);
/*devm_ioremap_resource()函数完成内存映射，得到RTC外设寄存器物理基地址对应的虚拟地址*/
if (IS_ERR(rtc->base))
return PTR_ERR(rtc->base);
rtc->data = (struct stm32_rtc_data *)
of_device_get_match_data(&pdev->dev);
regs = &rtc->data->regs;
if (rtc->data->need_dbp) {
rtc->dbp = syscon_regmap_lookup_by_phandle(pdev->dev.of_node,
"st,syscfg");
if (IS_ERR(rtc->dbp)) {
dev_err(&pdev->dev, "no st,syscfg\n");
return PTR_ERR(rtc->dbp);
}
ret = of_property_read_u32_index(pdev->dev.of_node, "st,syscfg",
1, &rtc->dbp_reg);
if (ret) {
dev_err(&pdev->dev, "can't read DBP register offset\n");
return ret;
}
ret = of_property_read_u32_index(pdev->dev.of_node, "st,syscfg",
2, &rtc->dbp_mask);
if (ret) {
dev_err(&pdev->dev, "can't read DBP register mask\n");
return ret;
}
}
if (!rtc->data->has_pclk) {
rtc->pclk = NULL;
rtc->rtc_ck = devm_clk_get(&pdev->dev, NULL);
} else {
rtc->pclk = devm_clk_get(&pdev->dev, "pclk");
if (IS_ERR(rtc->pclk)) {
if (PTR_ERR(rtc->pclk) != -EPROBE_DEFER)
dev_err(&pdev->dev, "no pclk clock");
return PTR_ERR(rtc->pclk);
}
rtc->rtc_ck = devm_clk_get(&pdev->dev, "rtc_ck");
}
if (IS_ERR(rtc->rtc_ck)) {
if (PTR_ERR(rtc->pclk) != -EPROBE_DEFER)
dev_err(&pdev->dev, "no rtc_ck clock");
return PTR_ERR(rtc->rtc_ck);
}
if (rtc->data->has_pclk) {
ret = clk_prepare_enable(rtc->pclk);
if (ret)
return ret;
}
ret = clk_prepare_enable(rtc->rtc_ck);/*使能预分频器时钟*/
if (ret)
goto err;
if (rtc->data->need_dbp)
regmap_update_bits(rtc->dbp, rtc->dbp_reg,
rtc->dbp_mask, rtc->dbp_mask);
/*
* After a system reset, RTC_ISR.INITS flag can be read to check if
* the calendar has been initialized or not. INITS flag is reset by a
* power-on reset (no vbat, no power-supply). It is not reset if
* rtc_ck parent clock has changed (so RTC prescalers need to be
* changed). That's why we cannot rely on this flag to know if RTC
* init has to be done.
*/
ret = stm32_rtc_init(pdev, rtc);
/**初始化STM32MP1的rtc寄存器*/
if (ret)
goto err;
rtc->irq_alarm = platform_get_irq(pdev, 0);
/*获取设备树的中断号*/
if (rtc->irq_alarm <= 0) {
ret = rtc->irq_alarm;
goto err;
}
ret = device_init_wakeup(&pdev->dev, true);
if (ret)
goto err;
ret = dev_pm_set_wake_irq(&pdev->dev, rtc->irq_alarm);
if (ret)
goto err;
platform_set_drvdata(pdev, rtc);
rtc->rtc_dev = devm_rtc_device_register(&pdev->dev, pdev->name,&stm32_rtc_ops, THIS_MODULE);
/*注册RTC类设备*/
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_threaded_irq(&pdev->dev, rtc->irq_alarm, NULL,
stm32_rtc_alarm_irq, IRQF_ONESHOT,
pdev->name, rtc);
/*RTC的“Alarm A”中断服务函数为stm32_rtc_alarm_irq()*/
if (ret) {
dev_err(&pdev->dev, "IRQ%d (alarm interrupt) already claimed\n",
rtc->irq_alarm);
goto err;
}
if (rtc->data->has_lsco) {
ret = of_property_read_s32(pdev->dev.of_node,
"st,lsco", &rtc->lsco);
if (!ret) {
ret = stm32_rtc_clk_lsco_register(pdev);
if (ret)
dev_warn(&pdev->dev,
"LSCO clock registration failed: %d\n",
ret);
} else {
rtc->lsco = ret;
dev_dbg(&pdev->dev, "No LSCO clock: %d\n", ret);
}
}
/*
* If INITS flag is reset (calendar year field set to 0x00), calendar
* must be initialized
*/
if (!(readl_relaxed(rtc->base + regs->isr) & STM32_RTC_ISR_INITS))
dev_warn(&pdev->dev, "Date/Time must be initialized\n");
if (regs->verr != UNDEF_REG) {
u32 ver = readl_relaxed(rtc->base + regs->verr);
dev_info(&pdev->dev, "registered rev:%d.%d\n",
(ver >> STM32_RTC_VERR_MAJREV_SHIFT) & 0xF,
(ver >> STM32_RTC_VERR_MINREV_SHIFT) & 0xF);
}
return 0;
err:
if (rtc->data->has_pclk)
clk_disable_unprepare(rtc->pclk);
clk_disable_unprepare(rtc->rtc_ck);
if (rtc->data->need_dbp)
regmap_update_bits(rtc->dbp, rtc->dbp_reg, rtc->dbp_mask, 0);
dev_pm_clear_wake_irq(&pdev->dev);
device_init_wakeup(&pdev->dev, false);
return ret;
}
/*platform的remove函数为stm32_rtc_remove()*/
static int stm32_rtc_remove(struct platform_device *pdev)
{
struct stm32_rtc *rtc = platform_get_drvdata(pdev);
const struct stm32_rtc_registers *regs = &rtc->data->regs;
unsigned int cr;
if (!IS_ERR_OR_NULL(rtc->clk_lsco))
clk_unregister_gate(rtc->clk_lsco);
/* Disable interrupts */
stm32_rtc_wpr_unlock(rtc);/*“RTC寄存器“解锁，允许写入*/
cr = readl_relaxed(rtc->base + regs->cr);
cr &= ~STM32_RTC_CR_ALRAIE;
writel_relaxed(cr, rtc->base + regs->cr);
stm32_rtc_wpr_lock(rtc);/*写错值，会重新激活“RTC寄存器“写保护，不允许写RTC寄存器*/
clk_disable_unprepare(rtc->rtc_ck);
if (rtc->data->has_pclk)
clk_disable_unprepare(rtc->pclk);
/* Enable backup domain write protection if needed */
if (rtc->data->need_dbp)
regmap_update_bits(rtc->dbp, rtc->dbp_reg, rtc->dbp_mask, 0);
dev_pm_clear_wake_irq(&pdev->dev);
device_init_wakeup(&pdev->dev, false);
return 0;
}
#ifdef CONFIG_PM_SLEEP
/*RTC暂停工作*/
static int stm32_rtc_suspend(struct device *dev)
{
struct stm32_rtc *rtc = dev_get_drvdata(dev);
if (rtc->data->has_pclk)
clk_disable_unprepare(rtc->pclk);
return 0;
}
/*RTC恢复工作*/
static int stm32_rtc_resume(struct device *dev)
{
struct stm32_rtc *rtc = dev_get_drvdata(dev);
int ret = 0;
if (rtc->data->has_pclk) {
ret = clk_prepare_enable(rtc->pclk);
if (ret)
return ret;
}
ret = stm32_rtc_wait_sync(rtc);/*令“日历影子寄存器“同步*/
if (ret < 0)
return ret;
return ret;
}
#endif
static const struct dev_pm_ops stm32_rtc_pm_ops = {
SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(stm32_rtc_suspend, stm32_rtc_resume)
};
/*标准的platform驱动框架*/
static struct platform_driver stm32_rtc_driver = {
.probe = stm32_rtc_probe,/*platform的probe函数为stm32_rtc_probe()*/
.remove = stm32_rtc_remove,/*platform的remove函数为stm32_rtc_remove()*/
.driver = {
.name = DRIVER_NAME,/* 驱动名字，用于和设备匹配 */
.pm = &stm32_rtc_pm_ops,
.of_match_table = stm32_rtc_of_match,/*设备树匹配表*/
},
};
module_platform_driver(stm32_rtc_driver);
//stm32_rtc_driver为platform_driver结构
//用来向linux内核注册platform驱动
MODULE_ALIAS("platform:" DRIVER_NAME);
MODULE_AUTHOR("Amelie Delaunay <amelie.delaunay@st.com>");//添加作者名字
MODULE_DESCRIPTION("STMicroelectronics STM32 Real Time Clock driver");//模块介绍
MODULE_LICENSE("GPL v2");//LICENSE采用“GPL协议”
4、编译设备树
①打开VSCode中的终端，输入“make uImage dtbs LOADADDR=0XC2000040 -j8回车”，执行编译“Image”和“dtbs”，并指定装载的起始地址为0XC2000040，j8表示指定采用8线程执行。“make dtbs”，用来指定编译设备树。见下图：
②输入“ls arch/arm/boot/uImage -l”
查看是否生成了新的“uImage”文件
③输入“ls arch/arm/boot/dts/stm32mp157d-atk.dtb -l”
查看是否生成了新的“stm32mp157d-atk.dtb”文件
4)、拷贝输出的文件：
①输入“cp arch/arm/boot/uImage /home/zgq/linux/atk-mp1/linux/bootfs/ -f回车”，执行文件拷贝，准备烧录到EMMC；
②输入“cp arch/arm/boot/dts/stm32mp157d-atk.dtb /home/zgq/linux/atk-mp1/linux/bootfs/ -f回车”，执行文件拷贝，准备烧录到EMMC
③输入“cp arch/arm/boot/uImage /home/zgq/linux/tftpboot/ -f回车”，执行文件拷贝，准备从tftp下载；
④输入“cp arch/arm/boot/dts/stm32mp157d-atk.dtb /home/zgq/linux/tftpboot/ -f回车”，执行文件拷贝，准备从tftp下载；
⑤输入“ls -l /home/zgq/linux/atk-mp1/linux/bootfs/回车”，查看“/home/zgq/linux/atk-mp1/linux/bootfs/”目录下的所有文件和文件夹
⑥输入“ls -l /home/zgq/linux/tftpboot/回车”，查看“/home/zgq/linux/tftpboot/”目录下的所有文件和文件夹
⑦输入“chmod 777 /home/zgq/linux/tftpboot/stm32mp157d-atk.dtb回车”
给“stm32mp157d-atk.dtb”文件赋予可执行权限
⑧输入“chmod 777 /home/zgq/linux/tftpboot/uImage回车” ,给“uImage”文件赋予可执行权限
⑨输入“ls /home/zgq/linux/tftpboot/ -l回车”，查看“/home/zgq/linux/tftpboot/”目录下的所有文件和文件夹
5、测试
①给开发板上电,启动开发板，从网络下载程序
②输入“root”
③输入“date回车”,查看时间。
④输入“date --help回车”,查看date命令如何设置系统时间。
⑤输入“date -s "2025-02-09 13:16:00"回车”,修改当前时间，但还没有写入到STM32MP1内部RTC里面或其他的RTC芯片里面，因此，系统重启以后时间又会丢失。
⑥输入“date回车”,查看时间。
⑦输入“hwclock -w回车”,将当前的系统时间写入到RTC里。
⑧重启开发板
