Re: [PATCH v8 18/25] powerpc: Implement nvram sync ioctl

On Sun, Dec 30, 2018 at 8:25 AM Finn Thain [off-list ref] wrote:

On Sat, 29 Dec 2018, Arnd Bergmann wrote:

quoted

quoted

--- 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?

       Arnd