powerpc/nvram: Allow byte length reads from mmio NVRAM driver

Add a byte length read and write interface compatible with the
nvram_generic driver interface to the mmio driver.

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

1 files changed, 32 insertions, 0 deletions

diff --git a/arch/powerpc/sysdev/mmio_nvram.c b/arch/powerpc/sysdev/mmio_nvram.c
index 7b49633a4bd0..207324209065 100644
--- a/arch/powerpc/sysdev/mmio_nvram.c
+++ b/arch/powerpc/sysdev/mmio_nvram.c
@@ -53,6 +53,23 @@ static ssize_t mmio_nvram_read(char *buf, size_t count, loff_t *index)
         return count;
 }
 
+static unsigned char mmio_nvram_read_val(int addr)
+{
+        unsigned long flags;
+        unsigned char val;
+
+        if (addr >= mmio_nvram_len)
+                return 0xff;
+
+        spin_lock_irqsave(&mmio_nvram_lock, flags);
+
+        val = ioread8(mmio_nvram_start + addr);
+
+        spin_unlock_irqrestore(&mmio_nvram_lock, flags);
+
+        return val;
+}
+
 static ssize_t mmio_nvram_write(char *buf, size_t count, loff_t *index)
 {
         unsigned long flags;
@@ -72,6 +89,19 @@ static ssize_t mmio_nvram_write(char *buf, size_t count, loff_t *index)
         return count;
 }
 
+void mmio_nvram_write_val(int addr, unsigned char val)
+{
+        unsigned long flags;
+
+        if (addr < mmio_nvram_len) {
+                spin_lock_irqsave(&mmio_nvram_lock, flags);
+
+                iowrite8(val, mmio_nvram_start + addr);
+
+                spin_unlock_irqrestore(&mmio_nvram_lock, flags);
+        }
+}
+
 static ssize_t mmio_nvram_get_size(void)
 {
         return mmio_nvram_len;
@@ -114,6 +144,8 @@ int __init mmio_nvram_init(void)
         printk(KERN_INFO "mmio NVRAM, %luk at 0x%lx mapped to %p\n",
                mmio_nvram_len >> 10, nvram_addr, mmio_nvram_start);
 
+        ppc_md.nvram_read_val   = mmio_nvram_read_val;
+        ppc_md.nvram_write_val  = mmio_nvram_write_val;
         ppc_md.nvram_read       = mmio_nvram_read;
         ppc_md.nvram_write      = mmio_nvram_write;
         ppc_md.nvram_size       = mmio_nvram_get_size;