s2c2440 rtc 平台设备驱动卸载问题 oops

最新推荐文章于 2023-08-28 00:06:58 发布

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最新推荐文章于 2023-08-28 00:06:58 发布

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分类专栏：问题分析文章标签： c 平台 struct null module cmd

本文链接：https://blog.youkuaiyun.com/cnsecs/article/details/6700441

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这篇博客探讨了在S2C2440平台上遇到的RTC（实时时钟）平台设备驱动卸载时出现的Oops问题。作者通过分析gzliu_2440_rtc.c源码，并引用了相关函数和结构体的详细解释，发现错误发生在源码的第580行。经过检查，作者找到了解决方案，即注释掉该行代码，从而避免了错误的发生。

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（1）rtc平台设备驱动源码如下，gzliu_2440_rtc.c：

相关的函数及结构体参见：http://blog.youkuaiyun.com/gzliu_hit/article/details/6699277

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/string.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/interrupt.h>
#include <linux/rtc.h>
#include <linux/bcd.h>
#include <asm/hardware.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/rtc.h>
#include <asm/mach/time.h>
#include <asm/hardware/clock.h>
#include <asm/arch/regs-rtc.h>
// 包含RTC_AF的声明
#include <linux/mc146818rtc.h>

#undef S3C24XX_VA_RTC
#define S3C24XX_VA_RTC s3c2440_rtc_base

static struct resource *s3c2440_rtc_mem = NULL;

static void __iomem *s3c2440_rtc_base = NULL;
static int s3c2440_rtc_alarm_irq = NO_IRQ;
static int s3c2440_rtc_tick_irq  = NO_IRQ;
static int s3c2440_rtc_freq    = 1;                     // rtc tick中断频率

static DEFINE_SPINLOCK(s3c2440_rtc_pie_lock);

static int s3c2440_rtc_proc(char *buf)
{
	unsigned int rtcalm = readb(S3C2410_RTCALM);
	unsigned int ticnt = readb (S3C2410_TICNT);
	char *p = buf;
printk("@@@@@@@@@@@@@@@@@@@@@@\ngzliu s3c2440_rtc_proc()\n@@@@@@@@@@@@@@@@@@@@@@@@\n");

	p += sprintf(p, "alarm_IRQ\t: %s\n", (rtcalm & S3C2410_RTCALM_ALMEN) ? "yes" : "no" );
	p += sprintf(p, "periodic_IRQ\t: %s\n", (ticnt & S3C2410_TICNT_ENABLE) ? "yes" : "no" );
	p += sprintf(p, "periodic_freq\t: %d\n", s3c2440_rtc_freq);

	return p - buf;
}

static int s3c2440_rtc_getalarm(struct rtc_wkalrm *alrm)
{
	struct rtc_time *alm_tm = &alrm->time;
	unsigned int alm_en;
printk("@@@@@@@@@@@@@@@@@@@@@@\ngzliu s3c2440_rtc_getalarm()\n@@@@@@@@@@@@@@@@@@@@@@@@\n");

	alm_tm->tm_sec  = readb(S3C2410_ALMSEC);
	alm_tm->tm_min  = readb(S3C2410_ALMMIN);
	alm_tm->tm_hour = readb(S3C2410_ALMHOUR);
	alm_tm->tm_mon  = readb(S3C2410_ALMMON);
	alm_tm->tm_mday = readb(S3C2410_ALMDATE);
	alm_tm->tm_year = readb(S3C2410_ALMYEAR);

	alm_en = readb(S3C2410_RTCALM);

	pr_debug("read alarm %02x %02x.%02x.%02x %02x/%02x/%02x\n", alm_en, alm_tm->tm_year, alm_tm->tm_mon, alm_tm->tm_mday, alm_tm->tm_hour, alm_tm->tm_min, alm_tm->tm_sec);


	/* decode the alarm enable field */

	if (alm_en & S3C2410_RTCALM_SECEN)
	{
		BCD_TO_BIN(alm_tm->tm_sec);
	}
	else
	{
		alm_tm->tm_sec = 0xff;
	}

	if (alm_en & S3C2410_RTCALM_MINEN)
	{
		BCD_TO_BIN(alm_tm->tm_min);
	}
	else
	{
		alm_tm->tm_min = 0xff;
	}

	if (alm_en & S3C2410_RTCALM_HOUREN)
	{
		BCD_TO_BIN(alm_tm->tm_hour);
	}
	else
	{
		alm_tm->tm_hour = 0xff;
	}

	if (alm_en & S3C2410_RTCALM_DAYEN)
	{
		BCD_TO_BIN(alm_tm->tm_mday);
	}
	else
	{
		alm_tm->tm_mday = 0xff;
	}

	if (alm_en & S3C2410_RTCALM_MONEN)
	{
		BCD_TO_BIN(alm_tm->tm_mon);
		alm_tm->tm_mon -= 1;
	}
	else
	{
		alm_tm->tm_mon = 0xff;
	}

	if (alm_en & S3C2410_RTCALM_YEAREN)
	{
		BCD_TO_BIN(alm_tm->tm_year);
	}
	else
	{
		alm_tm->tm_year = 0xffff;
	}

	/* todo - set alrm->enabled ? */

	return 0;
	
}/* s3c2440_rtc_getalarm(struct rtc_wkalrm *alrm) */

static int s3c2440_rtc_setalarm(struct rtc_wkalrm *alrm)
{
	struct rtc_time *tm = &alrm->time;
	unsigned int alrm_en;
printk("@@@@@@@@@@@@@@@@@@@@@@\ngzliu s3c2440_rtc_setalarm()\n@@@@@@@@@@@@@@@@@@@@@@@@\n");

	pr_debug("s3c2410_rtc_setalarm: %d, %02x/%02x/%02x %02x.%02x.%02x\n", alrm->enabled, tm->tm_mday & 0xff, tm->tm_mon & 0xff, tm->tm_year & 0xff, tm->tm_hour & 0xff, tm->tm_min & 0xff, tm->tm_sec);

	if (alrm->enabled || 1)
	{
		alrm_en = readb(S3C2410_RTCALM) & S3C2410_RTCALM_ALMEN;
		writeb(0x00, S3C2410_RTCALM);

		if (tm->tm_sec < 60 && tm->tm_sec >= 0)
		{
			alrm_en |= S3C2410_RTCALM_SECEN;
			writeb(BIN2BCD(tm->tm_sec), S3C2410_ALMSEC);
		}

		if (tm->tm_min < 60 && tm->tm_min >= 0)
		{
			alrm_en |= S3C2410_RTCALM_