+static int cgw_chk_csum_parms(s8 fr, s8 to, s8 re)
+{
+ /*
+ * absolute dlc values 0 .. 7 => 0 .. 7, e.g. data [0]
+ * relative to received dlc -1 .. -8 :
+ * e.g. for received dlc = 8
+ * -1 => index = 7 (data[7])
+ * -3 => index = 5 (data[5])
+ * -8 => index = 0 (data[0])
+ */
+
+ if (fr > -9 && fr < 8 &&
+ to > -9 && to < 8 &&
+ re > -9 && re < 8)
+ return 0;
+ else
+ return -EINVAL;
+}
+
+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)
+{
+ 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_crc8_rel(struct can_frame *cf, struct cgw_csum_crc8 *crc8)
+{
+ int from = calc_idx(crc8->from_idx, cf->can_dlc);
+ int to = calc_idx(crc8->to_idx, cf->can_dlc);
+ int res = calc_idx(crc8->result_idx, cf->can_dlc);
+ u8 crc = crc8->init_crc_val;
+ int i;
+
+ if (from < 0 || to < 0 || res < 0)
+ return;
+
+ if (from <= to) {
+ for (i = crc8->from_idx; i <= crc8->to_idx; i++)
+ crc = crc8->crctab[crc^cf->data[i]];
+ } else {
+ for (i = crc8->from_idx; i >= crc8->to_idx; i--)
+ crc = crc8->crctab[crc^cf->data[i]];
+ }
+
+ switch (crc8->profile) {
+
+ case CGW_CRC8PRF_1U8:
+ crc = crc8->crctab[crc^crc8->profile_data[0]];
+ break;
+
+ case CGW_CRC8PRF_16U8:
+ crc = crc8->crctab[crc^crc8->profile_data[cf->data[1] & 0xF]];
+ break;
+
+ case CGW_CRC8PRF_SFFID_XOR:
+ crc = crc8->crctab[crc^(cf->can_id & 0xFF)^
+ (cf->can_id >> 8 & 0xFF)];
+ break;
+
+ }
+
+ cf->data[crc8->result_idx] = crc^crc8->final_xor_val;
+}
+
+static void cgw_csum_crc8_pos(struct can_frame *cf, struct cgw_csum_crc8 *crc8)
+{
+ u8 crc = crc8->init_crc_val;
+ int i;
+
+ for (i = crc8->from_idx; i <= crc8->to_idx; i++)
+ crc = crc8->crctab[crc^cf->data[i]];
+
+ switch (crc8->profile) {
+
+ case CGW_CRC8PRF_1U8:
+ crc = crc8->crctab[crc^crc8->profile_data[0]];
+ break;
+
+ case CGW_CRC8PRF_16U8:
+ crc = crc8->crctab[crc^crc8->profile_data[cf->data[1] & 0xF]];
+ break;
+
+ case CGW_CRC8PRF_SFFID_XOR:
+ crc = crc8->crctab[crc^(cf->can_id & 0xFF)^
+ (cf->can_id >> 8 & 0xFF)];
+ break;
+ }
+
+ cf->data[crc8->result_idx] = crc^crc8->final_xor_val;
+}
+
+static void cgw_csum_crc8_neg(struct can_frame *cf, struct cgw_csum_crc8 *crc8)
+{
+ u8 crc = crc8->init_crc_val;
+ int i;
+
+ for (i = crc8->from_idx; i >= crc8->to_idx; i--)
+ crc = crc8->crctab[crc^cf->data[i]];
+
+ switch (crc8->profile) {
+
+ case CGW_CRC8PRF_1U8:
+ crc = crc8->crctab[crc^crc8->profile_data[0]];
+ break;
+
+ case CGW_CRC8PRF_16U8:
+ crc = crc8->crctab[crc^crc8->profile_data[cf->data[1] & 0xF]];
+ break;
+
+ case CGW_CRC8PRF_SFFID_XOR:
+ crc = crc8->crctab[crc^(cf->can_id & 0xFF)^
+ (cf->can_id >> 8 & 0xFF)];
+ break;
+ }
+
+ cf->data[crc8->result_idx] = crc^crc8->final_xor_val;
+}
+