Commit 2d58636e authored by Finn Thain's avatar Finn Thain Committed by Greg Kroah-Hartman
Browse files

char/nvram: Allow the set_checksum and initialize ioctls to be omitted 



The drivers/char/nvram.c module has previously supported only RTC "CMOS"
NVRAM, for which it provides appropriate checksum ioctls. Make these
ioctls optional so the module can be re-used with other kinds of NVRAM.

The ops struct methods that implement the ioctls now return error
codes so that a multi-platform kernel binary can do the right thing when
running on hardware without a suitable NVRAM.

Signed-off-by: default avatarFinn Thain <fthain@telegraphics.com.au>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent d5bbb502

drivers/char/nvram.c

+40 −30
Original line number Diff line number Diff line
@@ -136,16 +136,25 @@ static void __nvram_set_checksum(void) 
	__nvram_write_byte(sum & 0xff, PC_CKS_LOC + 1);

}



#if 0

void nvram_set_checksum(void)

static long pc_nvram_set_checksum(void)

{

	unsigned long flags;

	spin_lock_irq(&rtc_lock);

	__nvram_set_checksum();

	spin_unlock_irq(&rtc_lock);

	return 0;

}



	spin_lock_irqsave(&rtc_lock, flags);

static long pc_nvram_initialize(void)

{

	ssize_t i;



	spin_lock_irq(&rtc_lock);

	for (i = 0; i < NVRAM_BYTES; ++i)

		__nvram_write_byte(0, i);

	__nvram_set_checksum();

	spin_unlock_irqrestore(&rtc_lock, flags);

	spin_unlock_irq(&rtc_lock);

	return 0;

}

#endif  /*  0  */



static ssize_t pc_nvram_get_size(void)

{
@@ -156,6 +165,8 @@ const struct nvram_ops arch_nvram_ops = { 
	.read_byte      = pc_nvram_read_byte,

	.write_byte     = pc_nvram_write_byte,

	.get_size       = pc_nvram_get_size,

	.set_checksum   = pc_nvram_set_checksum,

	.initialize     = pc_nvram_initialize,

};

EXPORT_SYMBOL(arch_nvram_ops);

#endif /* CONFIG_X86 */
@@ -241,51 +252,50 @@ checksum_err: 
static long nvram_misc_ioctl(struct file *file, unsigned int cmd,

			     unsigned long arg)

{

	int i;

	long ret = -ENOTTY;



	switch (cmd) {



	case NVRAM_INIT:

		/* initialize NVRAM contents and checksum */

		if (!capable(CAP_SYS_ADMIN))

			return -EACCES;



		if (arch_nvram_ops.initialize != NULL) {

			mutex_lock(&nvram_mutex);

		spin_lock_irq(&rtc_lock);



		for (i = 0; i < NVRAM_BYTES; ++i)

			__nvram_write_byte(0, i);

		__nvram_set_checksum();



		spin_unlock_irq(&rtc_lock);

			ret = arch_nvram_ops.initialize();

			mutex_unlock(&nvram_mutex);

		return 0;



		}

		break;

	case NVRAM_SETCKS:

		/* just set checksum, contents unchanged (maybe useful after

		 * checksum garbaged somehow...) */

		if (!capable(CAP_SYS_ADMIN))

			return -EACCES;



		if (arch_nvram_ops.set_checksum != NULL) {

			mutex_lock(&nvram_mutex);

		spin_lock_irq(&rtc_lock);

		__nvram_set_checksum();

		spin_unlock_irq(&rtc_lock);

			ret = arch_nvram_ops.set_checksum();

			mutex_unlock(&nvram_mutex);

		return 0;



	default:

		return -ENOTTY;

		}

		break;

	}

	return ret;

}



static int nvram_misc_open(struct inode *inode, struct file *file)

{

	spin_lock(&nvram_state_lock);



	/* Prevent multiple readers/writers if desired. */

	if ((nvram_open_cnt && (file->f_flags & O_EXCL)) ||

	    (nvram_open_mode & NVRAM_EXCL) ||

	    ((file->f_mode & FMODE_WRITE) && (nvram_open_mode & NVRAM_WRITE))) {

	    (nvram_open_mode & NVRAM_EXCL)) {

		spin_unlock(&nvram_state_lock);

		return -EBUSY;

	}



	/* Prevent multiple writers if the set_checksum ioctl is implemented. */

	if ((arch_nvram_ops.set_checksum != NULL) &&

	    (file->f_mode & FMODE_WRITE) && (nvram_open_mode & NVRAM_WRITE)) {

		spin_unlock(&nvram_state_lock);

		return -EBUSY;

	}

include/linux/nvram.h

+2 −0
Original line number Diff line number Diff line
@@ -31,6 +31,8 @@ struct nvram_ops { 
	void            (*write_byte)(unsigned char, int);

	ssize_t         (*read)(char *, size_t, loff_t *);

	ssize_t         (*write)(char *, size_t, loff_t *);

	long            (*initialize)(void);

	long            (*set_checksum)(void);

};



extern const struct nvram_ops arch_nvram_ops;

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