V4L/DVB (4376): Make it possible for run-time calculation of control min/max in pvrusb2

The internal control implementation in the pvrusb2 driver normally
encodes integer range limits using literal values in a const
structure.  This change adds two function pointers, which if not null
will be called through in order to determine integer min / max
values.
Signed-off-by: Mike Isely <isely@pobox.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

drivers/media/video/pvrusb2/pvrusb2-ctrl.c

@@ -43,12 +43,17 @@ int pvr2_ctrl_set_mask_value(struct pvr2_ctrl *cptr,int mask,int val)
 			if (cptr->info->type == pvr2_ctl_bitmask) {
 				mask &= cptr->info->def.type_bitmask.valid_bits;
 			} else if (cptr->info->type == pvr2_ctl_int) {
-				if (val < cptr->info->def.type_int.min_value) {
-					break;
+				int lim;
+				lim = cptr->info->def.type_int.min_value;
+				if (cptr->info->get_min_value) {
+					cptr->info->get_min_value(cptr,&lim);
 				}
-				if (val > cptr->info->def.type_int.max_value) {
-					break;
+				if (val < lim) break;
+				lim = cptr->info->def.type_int.max_value;
+				if (cptr->info->get_max_value) {
+					cptr->info->get_max_value(cptr,&lim);
 				}
+				if (val > lim) break;
 			} else if (cptr->info->type == pvr2_ctl_enum) {
 				if (val >= cptr->info->def.type_enum.count) {
 					break;
@@ -91,7 +96,9 @@ int pvr2_ctrl_get_max(struct pvr2_ctrl *cptr)
 	int ret = 0;
 	if (!cptr) return 0;
 	LOCK_TAKE(cptr->hdw->big_lock); do {
-		if (cptr->info->type == pvr2_ctl_int) {
+		if (cptr->info->get_max_value) {
+			cptr->info->get_max_value(cptr,&ret);
+		} else if (cptr->info->type == pvr2_ctl_int) {
 			ret = cptr->info->def.type_int.max_value;
 		}
 	} while(0); LOCK_GIVE(cptr->hdw->big_lock);
@@ -105,7 +112,9 @@ int pvr2_ctrl_get_min(struct pvr2_ctrl *cptr)
 	int ret = 0;
 	if (!cptr) return 0;
 	LOCK_TAKE(cptr->hdw->big_lock); do {
-		if (cptr->info->type == pvr2_ctl_int) {
+		if (cptr->info->get_min_value) {
+			cptr->info->get_min_value(cptr,&ret);
+		} else if (cptr->info->type == pvr2_ctl_int) {
 			ret = cptr->info->def.type_int.min_value;
 		}
 	} while(0); LOCK_GIVE(cptr->hdw->big_lock);

drivers/media/video/pvrusb2/pvrusb2-hdw-internal.h

@@ -80,6 +80,8 @@ struct pvr2_ctl_info {
 
 	/* Control's implementation */
 	pvr2_ctlf_get_value get_value;      /* Get its value */
+	pvr2_ctlf_get_value get_min_value;  /* Get minimum allowed value */
+	pvr2_ctlf_get_value get_max_value;  /* Get maximum allowed value */
 	pvr2_ctlf_set_value set_value;      /* Set its value */
 	pvr2_ctlf_val_to_sym val_to_sym;    /* Custom convert value->symbol */
 	pvr2_ctlf_sym_to_val sym_to_val;    /* Custom convert symbol->value */