gmux: Add generic write32 function

Move the special-cased backlight update function to a generic gmux_write32
function.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Cc: Seth Forshee <seth.forshee@canonical.com>

1 files changed, 13 insertions, 10 deletions

diff --git a/drivers/platform/x86/apple-gmux.c b/drivers/platform/x86/apple-gmux.c
index 905fa01ac8df..c9db50729f6f 100644
--- a/drivers/platform/x86/apple-gmux.c
+++ b/drivers/platform/x86/apple-gmux.c
@@ -75,6 +75,18 @@ static inline u32 gmux_read32(struct apple_gmux_data *gmux_data, int port)
         return inl(gmux_data->iostart + port);
 }
 
+static inline u32 gmux_write32(struct apple_gmux_data *gmux_data, int port,
+                               u32 val)
+{
+        int i;
+        u8 tmpval;
+
+        for (i = 0; i < 4; i++) {
+                tmpval = (val >> (i * 8)) & 0xff;
+                outb(tmpval, port + i);
+        }
+}
+
 static int gmux_get_brightness(struct backlight_device *bd)
 {
         struct apple_gmux_data *gmux_data = bl_get_data(bd);
@@ -90,16 +102,7 @@ static int gmux_update_status(struct backlight_device *bd)
         if (bd->props.state & BL_CORE_SUSPENDED)
                 return 0;
 
-        /*
-         * Older gmux versions require writing out lower bytes first then
-         * setting the upper byte to 0 to flush the values. Newer versions
-         * accept a single u32 write, but the old method also works, so we
-         * just use the old method for all gmux versions.
-         */
-        gmux_write8(gmux_data, GMUX_PORT_BRIGHTNESS, brightness);
-        gmux_write8(gmux_data, GMUX_PORT_BRIGHTNESS + 1, brightness >> 8);
-        gmux_write8(gmux_data, GMUX_PORT_BRIGHTNESS + 2, brightness >> 16);
-        gmux_write8(gmux_data, GMUX_PORT_BRIGHTNESS + 3, 0);
+        gmux_write32(gmux_data, GMUX_PORT_BRIGHTNESS, brightness);
 
         return 0;
 }