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authorFinn Thain <fthain@telegraphics.com.au>2019-01-15 15:18:56 +1100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-01-22 10:21:43 +0100
commit2d58636e0af724f38acad25246c1625efec36122 (patch)
treedb6c44e29c9245169f2ce530f3ee30bce4fe9848 /drivers/char
parentd5bbb5021ce8d9ff561c7469f5b4589ccb3bc4a6 (diff)
downloadlinux-2d58636e0af724f38acad25246c1625efec36122.tar.bz2
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: Finn Thain <fthain@telegraphics.com.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/char')
-rw-r--r--drivers/char/nvram.c70
1 files changed, 40 insertions, 30 deletions
diff --git a/drivers/char/nvram.c b/drivers/char/nvram.c
index 2df391f78986..f88ef41d0598 100644
--- a/drivers/char/nvram.c
+++ b/drivers/char/nvram.c
@@ -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;
- 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);
- mutex_unlock(&nvram_mutex);
- return 0;
-
+ if (arch_nvram_ops.initialize != NULL) {
+ mutex_lock(&nvram_mutex);
+ ret = arch_nvram_ops.initialize();
+ mutex_unlock(&nvram_mutex);
+ }
+ break;
case NVRAM_SETCKS:
/* just set checksum, contents unchanged (maybe useful after
* checksum garbaged somehow...) */
if (!capable(CAP_SYS_ADMIN))
return -EACCES;
- mutex_lock(&nvram_mutex);
- spin_lock_irq(&rtc_lock);
- __nvram_set_checksum();
- spin_unlock_irq(&rtc_lock);
- mutex_unlock(&nvram_mutex);
- return 0;
-
- default:
- return -ENOTTY;
+ if (arch_nvram_ops.set_checksum != NULL) {
+ mutex_lock(&nvram_mutex);
+ ret = arch_nvram_ops.set_checksum();
+ mutex_unlock(&nvram_mutex);
+ }
+ 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;
}