On Mon, 31 Dec 2018, Arnd Bergmann wrote:
On Sun, Dec 30, 2018 at 8:25 AM Finn Thain <fthain@xxxxxxxxxxxxxxxxxxx> wrote:
On Sat, 29 Dec 2018, Arnd Bergmann wrote:
--- a/drivers/char/nvram.c
+++ b/drivers/char/nvram.c
@@ -48,6 +48,10 @@
#include <linux/mutex.h>
#include <linux/pagemap.h>
+#ifdef CONFIG_PPC
+#include <asm/nvram.h>
+#include <asm/machdep.h>
+#endif
static DEFINE_MUTEX(nvram_mutex);
static DEFINE_SPINLOCK(nvram_state_lock);
@@ -331,6 +335,37 @@ static long nvram_misc_ioctl(struct file *file, unsigned int cmd,
long ret = -ENOTTY;
switch (cmd) {
+#ifdef CONFIG_PPC
+ case OBSOLETE_PMAC_NVRAM_GET_OFFSET:
+ pr_warn("nvram: Using obsolete PMAC_NVRAM_GET_OFFSET ioctl\n");
+ /* fall through */
+ case IOC_NVRAM_GET_OFFSET:
+ ret = -EINVAL;
+#ifdef CONFIG_PPC_PMAC
I think it would make be nicer here to keep the ppc bits in arch/ppc,
and instead add a .ioctl() callback to nvram_ops.
The problem with having an nvram_ops.ioctl() method is the code in the
!PPC branch. That code would get duplicated because it's needed by
both X86 and M68K, to implement the checksum ioctls.
I was thinking you'd just have a common ioctl function that falls back
to the .ioctl callback for any unhandled commands like
switch (cmd) {
case NVRAM_INIT:
...
break;
case ...:
break;
default:
if (ops->ioctl)
return ops->ioctl(...);
return -EINVAL;
}
Would that work?
There are no ioctls common to all architectures. So your example becomes,
static long nvram_misc_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
if (ops->ioctl)
return ops->ioctl(file, cmd, arg);
return -ENOTTY;
}
And then my objection is the same: m68k and x86 now have to duplicate
their common ops->ioctl() implementation.
Here's a compromise that avoids some code duplication.
switch (cmd) {
#if defined(CONFIG_X86) || defined(CONFIG_M68K)
case NVRAM_INIT:
...
break;
case NVRAM_SETCKS:
...
break;
#endif
default:
if (ops->ioctl)
return ops->ioctl(...);
return -EINVAL;
}
But PPC64 and PPC32 also need to share their ops->ioctl() implementation.
It's not clear to me where that code would go.
Personally, I prefer the present patch series, or something similar, with
it's symmetry between nvram.c and nvram.h:
static long nvram_misc_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
long ret = -ENOTTY;
switch (cmd) {
#if defined(CONFIG_PPC)
case OBSOLETE_PMAC_NVRAM_GET_OFFSET:
...
case IOC_NVRAM_GET_OFFSET:
...
break;
case IOC_NVRAM_SYNC:
...
break;
#elif defined(CONFIG_X86) || defined(CONFIG_M68K)
case NVRAM_INIT:
...
break;
case NVRAM_SETCKS:
...
break;
#endif
}
return ret;
}
... versus the struct definition in nvram.h,
struct nvram_ops {
ssize_t (*read)(char *, size_t, loff_t *);
ssize_t (*write)(char *, size_t, loff_t *);
unsigned char (*read_byte)(int);
void (*write_byte)(unsigned char, int);
ssize_t (*get_size)(void);
#if defined(CONFIG_PPC)
long (*sync)(void);
int (*get_partition)(int);
#elif defined(CONFIG_X86) || defined(CONFIG_M68K)
long (*set_checksum)(void);
long (*initialize)(void);
#endif
};
Which of these alternatives do you prefer? Is there a better way?
--
Arnd
