efifb(4): WSDISPLAYIO_{GET,SET}PARAM ioctl support

[Anton Lindqvist]

This allows the brightness on my Dell Latitude 3160 to be adjusted
through wsconsctl(1).

Index: arch/amd64/amd64/efifb.c
===================================================================
RCS file: /cvs/src/sys/arch/amd64/amd64/efifb.c,v
retrieving revision 1.9
diff -u -p -r1.9 efifb.c
--- arch/amd64/amd64/efifb.c    21 Jun 2016 15:24:55 -0000      1.9
+++ arch/amd64/amd64/efifb.c    11 Dec 2016 09:25:04 -0000
@@ -104,6 +104,9 @@ int  efifb_load_font(void *, void *, str
 
 struct cb_framebuffer *cb_find_fb(paddr_t);
 
+extern int     (*ws_get_param)(struct wsdisplay_param *);
+extern int     (*ws_set_param)(struct wsdisplay_param *);
+
 const struct cfattach efifb_ca = {
        sizeof(struct efifb_softc), efifb_match, efifb_attach, NULL
 };
@@ -235,6 +238,16 @@ efifb_ioctl(void *v, u_long cmd, caddr_t
        struct wsdisplay_fbinfo *wdf;
 
        switch (cmd) {
+       case WSDISPLAYIO_GETPARAM:
+               if (ws_get_param != NULL)
+                       return (*ws_get_param)((struct wsdisplay_param *)data);
+               else
+                       return (-1);
+       case WSDISPLAYIO_SETPARAM:
+               if (ws_set_param != NULL)
+                       return (*ws_set_param)((struct wsdisplay_param *)data);
+               else
+                       return (-1);
        case WSDISPLAYIO_GTYPE:
                *(u_int *)data = WSDISPLAY_TYPE_EFIFB;
                break;