powerpc/nvram: Enable use Generic NVRAM driver for different size chips

Remove the reliance on a staticly defined NVRAM size, allowing
platforms to support NVRAMs with sizes differing from the standard.

A fall back value is provided for platforms not supporting this extension.

Signed-off-by: Martyn Welch <martyn.welch@gefanuc.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

2 files changed, 11 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/nvram.h b/arch/powerpc/include/asm/nvram.h
index efde5ac82f7b..6c587eddee59 100644
--- a/arch/powerpc/include/asm/nvram.h
+++ b/arch/powerpc/include/asm/nvram.h
@@ -107,6 +107,9 @@ extern void	pmac_xpram_write(int xpaddr, u8 data);
 /* Synchronize NVRAM */
 extern void     nvram_sync(void);
 
+/* Determine NVRAM size */
+extern ssize_t nvram_get_size(void);
+
 /* Normal access to NVRAM */
 extern unsigned char nvram_read_byte(int i);
 extern void nvram_write_byte(unsigned char c, int i);
diff --git a/arch/powerpc/kernel/setup_32.c b/arch/powerpc/kernel/setup_32.c
index e1e3059cf34b..53bcf3d792db 100644
--- a/arch/powerpc/kernel/setup_32.c
+++ b/arch/powerpc/kernel/setup_32.c
@@ -210,6 +210,14 @@ void nvram_write_byte(unsigned char val, int addr)
 }
 EXPORT_SYMBOL(nvram_write_byte);
 
+ssize_t nvram_get_size(void)
+{
+        if (ppc_md.nvram_size)
+                return ppc_md.nvram_size();
+        return -1;
+}
+EXPORT_SYMBOL(nvram_get_size);
+
 void nvram_sync(void)
 {
         if (ppc_md.nvram_sync)