+static inline int calc_idx(int idx, int rx_dlc)
+{
+ if (idx < 0)
+ return rx_dlc + idx;
+ else
+ return idx;
+}
+
+static void cgw_csum_xor_rel(struct can_frame *cf, struct cgw_csum_xor *xor)
+{
+ int from = calc_idx(xor->from_idx, cf->can_dlc);
+ int to = calc_idx(xor->to_idx, cf->can_dlc);
+ int res = calc_idx(xor->result_idx, cf->can_dlc);
+ u8 val = xor->init_xor_val;
+ int i;
+
+ if (from < 0 || to < 0 || res < 0)
+ return;
+
+ if (from <= to) {
+ for (i = from; i <= to; i++)
+ val ^= cf->data[i];
+ } else {
+ for (i = from; i >= to; i--)
+ val ^= cf->data[i];
+ }
+
+ cf->data[res] = val;
+}
+
+static void cgw_csum_xor_pos(struct can_frame *cf, struct cgw_csum_xor *xor)
+{
+ u8 val = xor->init_xor_val;
+ int i;
+
+ for (i = xor->from_idx; i <= xor->to_idx; i++)
+ val ^= cf->data[i];
+
+ cf->data[xor->result_idx] = val;
+}
+
+static void cgw_csum_xor_neg(struct can_frame *cf, struct cgw_csum_xor *xor)