[PATCH v9 05/22] m68k/atari: Implement arch_nvram_ops struct

[Finn Thain]

By implementing an arch_nvram_ops struct, a platform can re-use the
drivers/char/nvram.c module without needing any arch-specific code
in that module. Atari does so here.

Acked-by: Geert Uytterhoeven <ge...@linux-m68k.org>
Signed-off-by: Finn Thain <fth...@telegraphics.com.au>
---
Changed since v8:
 - Added static inline wrapper functions to nvram.h.
 - Removed excess whitespace.
 - Renamed functions to avoid collisions with nvram.h wrapper functions.
 - Moved nvram_check_checksum() changes to the preceding patch.
---
 arch/m68k/atari/nvram.c | 49 +++++++++++++++++++++++++++++++++++++++++
 include/linux/nvram.h   | 14 ++++++++++++
 2 files changed, 63 insertions(+)

diff --git a/arch/m68k/atari/nvram.c b/arch/m68k/atari/nvram.c
index 1d767847ffa6..e75adebe6e7d 100644
--- a/arch/m68k/atari/nvram.c
+++ b/arch/m68k/atari/nvram.c
@@ -74,6 +74,55 @@ static void __nvram_set_checksum(void)
        __nvram_write_byte(sum, ATARI_CKS_LOC + 1);
 }
 
+static ssize_t atari_nvram_read(char *buf, size_t count, loff_t *ppos)
+{
+       char *p = buf;
+       loff_t i;
+
+       spin_lock_irq(&rtc_lock);
+       if (!__nvram_check_checksum()) {
+               spin_unlock_irq(&rtc_lock);
+               return -EIO;
+       }
+       for (i = *ppos; count > 0 && i < NVRAM_BYTES; --count, ++i, ++p)
+               *p = __nvram_read_byte(i);
+       spin_unlock_irq(&rtc_lock);
+
+       *ppos = i;
+       return p - buf;
+}
+
+static ssize_t atari_nvram_write(char *buf, size_t count, loff_t *ppos)
+{
+       char *p = buf;
+       loff_t i;
+
+       spin_lock_irq(&rtc_lock);
+       if (!__nvram_check_checksum()) {
+               spin_unlock_irq(&rtc_lock);
+               return -EIO;
+       }
+       for (i = *ppos; count > 0 && i < NVRAM_BYTES; --count, ++i, ++p)
+               __nvram_write_byte(*p, i);
+       __nvram_set_checksum();
+       spin_unlock_irq(&rtc_lock);
+
+       *ppos = i;
+       return p - buf;
+}
+
+static ssize_t atari_nvram_get_size(void)
+{
+       return NVRAM_BYTES;
+}
+
+const struct nvram_ops arch_nvram_ops = {
+       .read           = atari_nvram_read,
+       .write          = atari_nvram_write,
+       .get_size       = atari_nvram_get_size,
+};
+EXPORT_SYMBOL(arch_nvram_ops);
+
 #ifdef CONFIG_PROC_FS
 static struct {
        unsigned char val;
diff --git a/include/linux/nvram.h b/include/linux/nvram.h
index eb5b52a9a747..a1e01dc89759 100644
--- a/include/linux/nvram.h
+++ b/include/linux/nvram.h
@@ -5,8 +5,18 @@
 #include <linux/errno.h>
 #include <uapi/linux/nvram.h>
 
+struct nvram_ops {
+       ssize_t         (*get_size)(void);
+       ssize_t         (*read)(char *, size_t, loff_t *);
+       ssize_t         (*write)(char *, size_t, loff_t *);
+};
+
+extern const struct nvram_ops arch_nvram_ops;
+
 static inline ssize_t nvram_get_size(void)
 {
+       if (arch_nvram_ops.get_size)
+               return arch_nvram_ops.get_size();
        return -ENODEV;
 }
 
@@ -21,11 +31,15 @@ static inline void nvram_write_byte(unsigned char val, int 
addr)
 
 static inline ssize_t nvram_read(char *buf, size_t count, loff_t *ppos)
 {
+       if (arch_nvram_ops.read)
+               return arch_nvram_ops.read(buf, count, ppos);
        return -ENODEV;
 }
 
 static inline ssize_t nvram_write(char *buf, size_t count, loff_t *ppos)
 {
+       if (arch_nvram_ops.write)
+               return arch_nvram_ops.write(buf, count, ppos);
        return -ENODEV;
 }
 
-- 
2.19.2