- /*********************************************************************************************************
- * @Description:s3c2410的rtc驱动的实现,rtc(real time clock)实时时钟的驱动是个很好的
- * 理解如果编写驱动的硬件,它包括了最基本的硬中断,软中断的底层机制;
- * s3c2410的RTC驱动的实现个人认为更是对linux设备驱动一个很好的例子,他是通过二层结构来
- * 实现的一个驱动,上层是一个arm common的公共层,对上提供标准的通用的RTC操作接口,下层由
- * 我们来实现针对自己的chip和自己要提供的功能来实现的一层驱动;
- *
- * @FileTree:
- **********************************************************************************************************
- linux-2.6.14.6
- |
- |--arch
- | |
- | |--arm
- | | |--mach-s3c2410
- | | | |-devs.c //包含了对各个部件的resource的分配和定义,在这看rtc的资源;
- | | |--common
- | | | |-rtctime.c //一个arm平台的通用rtc函数层,它对上隐藏了各种soc的rtc driver的区别;
- | | |--kernel
- | | | |-time.c //内核的初始化例程time_init()会调用的xxx_cmos_xxx函数的实现;定义了全局自旋锁rtc_lock用来串行化所有CPU对RTC的操作
- |
- |--drivers
- | |--char
- | | |-s3c2410-rtc.c //具体的s3c2410上的rtc chip的驱动实现,如果需要在arm平台的
- | | 板子上实现一个驱动,改写它就ok了。
- |
- |--include
- | |--asm-arm
- | | |--arch-s3c2410
- | | | |-regs-rtc.h //S3C2410 Internal RTC register definition refer to datasheet;
- | | |-rtc.h //arm平台rtc操作抽象层rtctime.c对应的.h
- | |--linux
- | | |-time.h //mktime的实现;
- | | |-rtc.h //公用RTC .h
- *
- *[小结]
- *1)提供给user的接口,在arch/arm/common/rtctime.c,include/asm-arm/rtc.h中实现,调用操作硬件驱动在drivers/char/s3c2410-rtc.c,include/asm-arm/arch-s3c2410/regs-rtc.h实现;
- *2)提供给kernel的接口,在arch/arm/kernel/time.c,include/linux/time.h中实现,调用操作硬件驱动在drivers/char/s3c2410-rtc.c,include/asm-arm/arch-s3c2410/regs-rtc.h实现;
- **********************************************************************************************************
- *
- * @Author: liyangth@gmail.com
- *
- * @Function List: <Functions>
- *
- * <Static functions>
- *
- *
- * @Changelog:
- * 2007-06-24 LiYang First version
- *
- * @FQA:
- * [50%]Q1.在驱动中要将设备注册到总线,必须将设备封装成struct device_driver;调查这个结构体中的每个成员.
- * [0%]Q2.在板子(什么类型)上什么样的设备要用总线(什么类型)注册?
- * [90%]Q3.
- * struct device --总线设备
- * struct device_driver --总线设备驱动
- * struct platform_device --平台设备
- * struct resource --平台资源
- *
- * [!0%]Q4.初始化rtc register的函数的后面的flag具体控制什么? (在s2s65a里是否可以用它控制是softReset or hardwareReset)
- *
- * [0%]Q5.什么时候调用suspend, resume?
- **********************************************************************************************************/
- /**//*****************************************************************************
- * Structures & Unions & Enums (#typedef)
- */
- /**//*[include/linux/device.h]
- *总线设备驱动结构体,将它注册到板子的总线上
- */
- static struct device_driver s3c2410_rtcdrv = ...{
- .name = "s3c2410-rtc",
- .owner = THIS_MODULE,
- .bus = &platform_bus_type, //总线类型,貌似不用管
- .probe = s3c2410_rtc_probe, //自检->初始化REG->注册到上一层
- .remove = s3c2410_rtc_remove, //注销
- .suspend = s3c2410_rtc_suspend, //[挂起???]
- .resume = s3c2410_rtc_resume, //[重起???]
- };
- /**//*[/include/asm-arm/rtc.h]
- *底层特别操作集,将他注册到上层的arm common操作层
- */
- static struct rtc_ops s3c2410_rtcops = ...{
- .owner = THIS_MODULE,
- .open = s3c2410_rtc_open,
- .release = s3c2410_rtc_release,
- .ioctl = s3c2410_rtc_ioctl,
- .read_time = s3c2410_rtc_gettime,
- .set_time = s3c2410_rtc_settime,
- .read_alarm = s3c2410_rtc_getalarm,
- .set_alarm = s3c2410_rtc_setalarm,
- .proc = s3c2410_rtc_proc,
- };
- /**//*****************************************************************************
- * Global Variables
- */
- s3c2410-rtc.c
- |
- |/**//* IRQ Handlers */
- |-s3c2410_rtc_alarmirq(int irq, void *id, struct pt_regs *r)
- | |
- | |-rtc_update(1, RTC_AF | RTC_IRQF); //获得中断标志,和唤醒read阻塞,异步通知;
- |
- |-s3c2410_rtc_tickirq(int irq, void *id, struct pt_regs *r)
- |
- |/**//* Update control registers,与硬件实现有关,refer to datasheet */
- |-s3c2410_rtc_setaie(int to)
- |-s3c2410_rtc_setpie(int to)
- |-s3c2410_rtc_setfreq(int freq)
- |
- |/**//* 实现了要插到上层arm common层的具体的硬件操作,来填充struct rtc_ops,这个具体与硬件相关的操作集会用
- | register_rtc注册到上层的 */
- |
- |-s3c2410_rtc_gettime(struct rtc_time *rtc_tm)
- |
- |-s3c2410_rtc_settime(struct rtc_time *tm)
- |
- |-s3c2410_rtc_getalarm(struct rtc_wkalrm *alrm)
- |
- |-s3c2410_rtc_setalarm(struct rtc_wkalrm *alrm)
- |
- |/**//*
- | * 插入到上层ioctl中的ioctl,上层中已经通过这个driver中的gettime,settime在其ioctl中实现了取得和设置时间
- | *,和一些共同的ioctl操作了
- | * 所以我们在这只要实现与硬件不同部分的ioctl操作 */
- |-s3c2410_rtc_ioctl(unsigned int cmd, unsigned long arg)
- |
- |-s3c2410_rtc_proc(char *buf)
- |-s3c2410_rtc_open(void)
- | |
- | |1.注册申请闹钟中断ISQ --s3c2410_rtc_alarmirq
- | |2.周期中断ISQ --s3c2410_rtc_tickirq
- |
- |-s3c2410_rtc_release(void)
- |
- |/**//* Initialize RTC Regs */
- |-s3c2410_rtc_enable(struct device *dev, int en)
- | |
- | |-if(!en)
- | |/**//*before power off, the RTCEN bit should be cleared to
- | | 0 to prevent inadvertent writing into RTC registers.*/
- | |1.将控制R的RTCEN位清0;
- | |
- | |2.disable interrupt.
- | |
- | |-else /**//* re-enable the device, and check it is ok */
- | |
- | |1.将控制R的RTCEN位致1。
- | |
- | |2.BCD count select.--0=Merge BCD counters
- | |
- | |3.RTC clock count reset.--0=noreset
- | |
- |
- |
- |
- |-s3c2410_rtc_probe(struct device *dev)
- | |[??]struct platform_device *pdev = to_platform_device(dev); //通过这个设备找到它宿主平台的大设备;
- | | struct resource *res;
- | |
- | |/**//* find the IRQs,RTC有2中中断,周期中断和闹钟中断 */
- | |-s3c2410_rtc_tickno = platform_get_irq(pdev, 1); //从平台上取得一个IRQ号给这个设备;
- | |
- | |/**//* get the memory region */
- | |-res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
- | |
- | |/**//* 向内核申请资源空间 */
- | |-s3c2410_rtc_mem = request_mem_region(res->start, res->end-res->start+1,
- pdev->name); //res->start这些资源的分配和在哪个段下,可以看../mach-s3c2410/devs.c
- | |
- | |/**//* 然后将物理地址映射到虚拟地址,这样驱动和内核就可以看到设备的I/O regs了 */
- | |-s3c2410_rtc_base = ioremap(res->start, res->end - res->start + 1);
- | |
- | |/**//* 初始化设备regs */
- | |-s3c2410_rtc_enable(dev, 1); //可以用后面这个1(这个flag在s2s65a中可以用ram0-7来保存,掉电不清的)来控制是softreset还是hardwarereset.
- | |
- | |-s3c2410_rtc_setfreq(s3c2410_rtc_freq); //设定RTC周期频率;
- | |
- | |/**//* 最关键的一步,将与具体不同的底层硬件相关的设备驱动注册给arm通用操作层common/rtctime.c */
- | |-register_rtc(&s3c2410_rtcops);
- |
- |-s3c2410_rtc_remove(struct device *dev)
- | |-unregister_rtc(&s3c2410_rtcops); //从上一层将s3c2410的rtc的device dirver operation set拔下来。
- | |
- | |-s3c2410_rtc_setpie(0); //disable 周期中断
- | |
- | |-s3c2410_rtc_setaie(0); //disable alarm interrupt
- | |
- | |-iounmap(s3c2410_rtc_base);
- | |
- | |-release_resource(s3c2410_rtc_mem);
- | |
- | |-kfree(s3c2410_rtc_mem); //[MQA]哪块kmalloc了呢,为什么这要free?
- |
- |
- |#ifdef CONFIG_PM //如果电源控制开关打开
- |
- |-s3c2410_rtc_suspend(struct device *dev, pm_message_t state, u32 level)
- | |
- | |if (level == SUSPEND_POWER_DOWN) //SUSPEND_POWER_DOWN在include/linux/device.h(generic, centralized driver model)中定义,这个里面是否是对设备的一些公用的行为的操作宏的定义呢?
- | | |1.保存周期中断寄存器的值;
- | | |
- | | |2.从RTC中读出时间
- | | |-s3c2410_rtc_gettime(&tm); //[local variable]struct rtc_time tm;
- | | |
- | | |3.将从RTC取出的时间Convert Gregorian date to seconds since 01-01-1970 00:00:00.
- | | |-rtc_tm_to_time(&tm, &time.tv_sec); //[arch/arm/common/rtctime.c]
- | | |
- | | |4.将系统时间和RTC时间的差值保存到s3c2410_rtc_delta里;
- | | |-save_time_delta(&s3c2410_rtc_delta, &time);
- | | |
- | | |5.启动RTC,注意这次启动后面的falg为0了;
- | | |-s3c2410_rtc_enable(dev, 0);
- |
- |
- |-s3c2410_rtc_resume(struct device *dev, u32 level)
- | |
- | |1.启动RTC,注意这次启动后面的falg为1了;
- | |-s3c2410_rtc_enable(dev, 1);
- | |
- | |2.从RTC中读出时间
- | |-s3c2410_rtc_gettime(&tm);
- | |
- | |3.转换
- | |-rtc_tm_to_time(&tm, &time.tv_sec);
- | |
- | |4.利用在suspend中保存的delta来恢复系统时间
- | |-restore_time_delta(&s3c2410_rtc_delta, &time);
- | |
- | |5.恢复周期中断寄存器的值;
- |
- |[LiY]
- |suspend(暂停,挂起)和resume(恢复,再开始)有点象关机前保存现场和开机后再恢复现场一样;
- |
- |#else
- |#define s3c2410_rtc_suspend NULL
- |#define s3c2410_rtc_resume NULL
- |#endif
- |
- |
- |module_init(s3c2410_rtc_init)
- |-s3c2410_rtc_init
- | |-driver_register(&s3c2410_rtcdrv);
- | | |[purpose]register driver with bus;
- |
- |module_exit(s3c2410_rtc_exit)
- |-s3c2410_rtc_exit(void)
- | |-driver_unregister(&s3c2410_rtcdrv)
- /**//*****************************************************************************
- * Extern Function Details
- */
- /**//**[drivers/base/driver.c]
- * driver_register - register driver with bus
- * @drv: driver to register
- *
- * We pass off most of the work to the bus_add_driver() call,
- * since most of the things we have to do deal with the bus
- * structures.
- *
- * The one interesting aspect is that we setup @drv->unloaded
- * as a completion that gets complete when the driver reference
- * count reaches 0.
- */
- int driver_register(struct device_driver * drv)
- ...{
- klist_init(&drv->klist_devices, klist_devices_get, klist_devices_put);
- init_completion(&drv->unloaded);
- return bus_add_driver(drv);
- }
- /**//**[drivers/base/platform.c]
- * platform_get_irq - get an IRQ for a device
- * @dev: platform device
- * @num: IRQ number index
- */
- int platform_get_irq(struct platform_device *dev, unsigned int num)
- ...{
- struct resource *r = platform_get_resource(dev, IORESOURCE_IRQ, num);
- return r ? r->start : 0;
- }
- /**//**[drivers/base/platform.c]
- * platform_get_resource - get a resource for a device
- * @dev: platform device
- * @type: resource type
- * @num: resource index
- */
- struct resource *
- platform_get_resource(struct platform_device *dev, unsigned int type,
- unsigned int num)
- ...{
- int i;
- for (i = 0; i < dev->num_resources; i++) ...{
- struct resource *r = &dev->resource[i];
- if ((r->flags & (IORESOURCE_IO|IORESOURCE_MEM|
- IORESOURCE_IRQ|IORESOURCE_DMA))
- == type)
- if (num-- == 0)
- return r;
- }
- return NULL;
- }
- /**//*[../include/linux/ioport.h]
- * Resources are tree-like, allowing
- * nesting etc..
- */
- struct resource ...{
- const char *name;
- unsigned long start, end;
- unsigned long flags;
- struct resource *parent, *sibling, *child;
- };
- /**//**[arch/arm/kernel/time.c]
- * save_time_delta - Save the offset between system time and RTC time
- * @delta: pointer to timespec to store delta
- * @rtc: pointer to timespec for current RTC time
- *
- * Return a delta between the system time and the RTC time, such
- * that system time can be restored later with restore_time_delta()
- *
- *[LiY]返回一个系统时间和RTC时间的差值,在重起或系统去读RTC后,可以再用这个差值(delta)来恢复系统时间(系统时间不一定非要和RTC时间相同的);
- */
- void save_time_delta(struct timespec *delta, struct timespec *rtc)
- ...{
- set_normalized_timespec(delta,
- xtime.tv_sec - rtc->tv_sec,
- xtime.tv_nsec - rtc->tv_nsec);
- }
- /**//***[arch/arm/kernel/time.c]
- * restore_time_delta - Restore the current system time
- * @delta: delta returned by save_time_delta()
- * @rtc: pointer to timespec for current RTC time
- */
- void restore_time_delta(struct timespec *delta, struct timespec *rtc)
- ...{
- struct timespec ts;
- set_normalized_timespec(&ts,
- delta->tv_sec + rtc->tv_sec,
- delta->tv_nsec + rtc->tv_nsec);
- do_settimeofday(&ts);
- }
- /**//*
- *[arch/arm/common/rtctime.c]
- */
- void rtc_update(unsigned long num, unsigned long events)
- ...{
- spin_lock(&rtc_lock);
- rtc_irq_data = (rtc_irq_data + (num << 8)) | events;
- spin_unlock(&rtc_lock);
- wake_up_interruptible(&rtc_wait);
- kill_fasync(&rtc_async_queue, SIGIO, POLL_IN);
- }
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