iwlwifi: mvm: implement remote wake

With remote wake, the firmware creates a TCP connection
and sends some configurable data on it, until a special
TCP data packet from the server is received that triggers
a wakeup. The configuration is a bit tricky because it is
based on packet pattern matching but this is hidden in
the driver and the exposed API in cfg80211 is just based
on the required TCP connection parameters.

Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 258 insertions, 0 deletions

diff --git a/drivers/net/wireless/iwlwifi/mvm/d3.c b/drivers/net/wireless/iwlwifi/mvm/d3.c
index 376a5776db90..d4578cefe445 100644
--- a/drivers/net/wireless/iwlwifi/mvm/d3.c
+++ b/drivers/net/wireless/iwlwifi/mvm/d3.c
@@ -62,8 +62,10 @@
  *****************************************************************************/
 
 #include <linux/etherdevice.h>
+#include <linux/ip.h>
 #include <net/cfg80211.h>
 #include <net/ipv6.h>
+#include <net/tcp.h>
 #include "iwl-modparams.h"
 #include "fw-api.h"
 #include "mvm.h"
@@ -402,6 +404,233 @@ static int iwl_mvm_send_proto_offload(struct iwl_mvm *mvm,
                                     sizeof(cmd), &cmd);
 }
 
+enum iwl_mvm_tcp_packet_type {
+        MVM_TCP_TX_SYN,
+        MVM_TCP_RX_SYNACK,
+        MVM_TCP_TX_DATA,
+        MVM_TCP_RX_ACK,
+        MVM_TCP_RX_WAKE,
+        MVM_TCP_TX_FIN,
+};
+
+static __le16 pseudo_hdr_check(int len, __be32 saddr, __be32 daddr)
+{
+        __sum16 check = tcp_v4_check(len, saddr, daddr, 0);
+        return cpu_to_le16(be16_to_cpu((__force __be16)check));
+}
+
+static void iwl_mvm_build_tcp_packet(struct iwl_mvm *mvm,
+                                     struct ieee80211_vif *vif,
+                                     struct cfg80211_wowlan_tcp *tcp,
+                                     void *_pkt, u8 *mask,
+                                     __le16 *pseudo_hdr_csum,
+                                     enum iwl_mvm_tcp_packet_type ptype)
+{
+        struct {
+                struct ethhdr eth;
+                struct iphdr ip;
+                struct tcphdr tcp;
+                u8 data[];
+        } __packed *pkt = _pkt;
+        u16 ip_tot_len = sizeof(struct iphdr) + sizeof(struct tcphdr);
+        int i;
+
+        pkt->eth.h_proto = cpu_to_be16(ETH_P_IP),
+        pkt->ip.version = 4;
+        pkt->ip.ihl = 5;
+        pkt->ip.protocol = IPPROTO_TCP;
+
+        switch (ptype) {
+        case MVM_TCP_TX_SYN:
+        case MVM_TCP_TX_DATA:
+        case MVM_TCP_TX_FIN:
+                memcpy(pkt->eth.h_dest, tcp->dst_mac, ETH_ALEN);
+                memcpy(pkt->eth.h_source, vif->addr, ETH_ALEN);
+                pkt->ip.ttl = 128;
+                pkt->ip.saddr = tcp->src;
+                pkt->ip.daddr = tcp->dst;
+                pkt->tcp.source = cpu_to_be16(tcp->src_port);
+                pkt->tcp.dest = cpu_to_be16(tcp->dst_port);
+                /* overwritten for TX SYN later */
+                pkt->tcp.doff = sizeof(struct tcphdr) / 4;
+                pkt->tcp.window = cpu_to_be16(65000);
+                break;
+        case MVM_TCP_RX_SYNACK:
+        case MVM_TCP_RX_ACK:
+        case MVM_TCP_RX_WAKE:
+                memcpy(pkt->eth.h_dest, vif->addr, ETH_ALEN);
+                memcpy(pkt->eth.h_source, tcp->dst_mac, ETH_ALEN);
+                pkt->ip.saddr = tcp->dst;
+                pkt->ip.daddr = tcp->src;
+                pkt->tcp.source = cpu_to_be16(tcp->dst_port);
+                pkt->tcp.dest = cpu_to_be16(tcp->src_port);
+                break;
+        default:
+                WARN_ON(1);
+                return;
+        }
+
+        switch (ptype) {
+        case MVM_TCP_TX_SYN:
+                /* firmware assumes 8 option bytes - 8 NOPs for now */
+                memset(pkt->data, 0x01, 8);
+                ip_tot_len += 8;
+                pkt->tcp.doff = (sizeof(struct tcphdr) + 8) / 4;
+                pkt->tcp.syn = 1;
+                break;
+        case MVM_TCP_TX_DATA:
+                ip_tot_len += tcp->payload_len;
+                memcpy(pkt->data, tcp->payload, tcp->payload_len);
+                pkt->tcp.psh = 1;
+                pkt->tcp.ack = 1;
+                break;
+        case MVM_TCP_TX_FIN:
+                pkt->tcp.fin = 1;
+                pkt->tcp.ack = 1;
+                break;
+        case MVM_TCP_RX_SYNACK:
+                pkt->tcp.syn = 1;
+                pkt->tcp.ack = 1;
+                break;
+        case MVM_TCP_RX_ACK:
+                pkt->tcp.ack = 1;
+                break;
+        case MVM_TCP_RX_WAKE:
+                ip_tot_len += tcp->wake_len;
+                pkt->tcp.psh = 1;
+                pkt->tcp.ack = 1;
+                memcpy(pkt->data, tcp->wake_data, tcp->wake_len);
+                break;
+        }
+
+        switch (ptype) {
+        case MVM_TCP_TX_SYN:
+        case MVM_TCP_TX_DATA:
+        case MVM_TCP_TX_FIN:
+                pkt->ip.tot_len = cpu_to_be16(ip_tot_len);
+                pkt->ip.check = ip_fast_csum(&pkt->ip, pkt->ip.ihl);
+                break;
+        case MVM_TCP_RX_WAKE:
+                for (i = 0; i < DIV_ROUND_UP(tcp->wake_len, 8); i++) {
+                        u8 tmp = tcp->wake_mask[i];
+                        mask[i + 6] |= tmp << 6;
+                        if (i + 1 < DIV_ROUND_UP(tcp->wake_len, 8))
+                                mask[i + 7] = tmp >> 2;
+                }
+                /* fall through for ethernet/IP/TCP headers mask */
+        case MVM_TCP_RX_SYNACK:
+        case MVM_TCP_RX_ACK:
+                mask[0] = 0xff; /* match ethernet */
+                /*
+                 * match ethernet, ip.version, ip.ihl
+                 * the ip.ihl half byte is really masked out by firmware
+                 */
+                mask[1] = 0x7f;
+                mask[2] = 0x80; /* match ip.protocol */
+                mask[3] = 0xfc; /* match ip.saddr, ip.daddr */
+                mask[4] = 0x3f; /* match ip.daddr, tcp.source, tcp.dest */
+                mask[5] = 0x80; /* match tcp flags */
+                /* leave rest (0 or set for MVM_TCP_RX_WAKE) */
+                break;
+        };
+
+        *pseudo_hdr_csum = pseudo_hdr_check(ip_tot_len - sizeof(struct iphdr),
+                                            pkt->ip.saddr, pkt->ip.daddr);
+}
+
+static int iwl_mvm_send_remote_wake_cfg(struct iwl_mvm *mvm,
+                                        struct ieee80211_vif *vif,
+                                        struct cfg80211_wowlan_tcp *tcp)
+{
+        struct iwl_wowlan_remote_wake_config *cfg;
+        struct iwl_host_cmd cmd = {
+                .id = REMOTE_WAKE_CONFIG_CMD,
+                .len = { sizeof(*cfg), },
+                .dataflags = { IWL_HCMD_DFL_NOCOPY, },
+                .flags = CMD_SYNC,
+        };
+        int ret;
+
+        if (!tcp)
+                return 0;
+
+        cfg = kzalloc(sizeof(*cfg), GFP_KERNEL);
+        if (!cfg)
+                return -ENOMEM;
+        cmd.data[0] = cfg;
+
+        cfg->max_syn_retries = 10;
+        cfg->max_data_retries = 10;
+        cfg->tcp_syn_ack_timeout = 1; /* seconds */
+        cfg->tcp_ack_timeout = 1; /* seconds */
+
+        /* SYN (TX) */
+        iwl_mvm_build_tcp_packet(
+                mvm, vif, tcp, cfg->syn_tx.data, NULL,
+                &cfg->syn_tx.info.tcp_pseudo_header_checksum,
+                MVM_TCP_TX_SYN);
+        cfg->syn_tx.info.tcp_payload_length = 0;
+
+        /* SYN/ACK (RX) */
+        iwl_mvm_build_tcp_packet(
+                mvm, vif, tcp, cfg->synack_rx.data, cfg->synack_rx.rx_mask,
+                &cfg->synack_rx.info.tcp_pseudo_header_checksum,
+                MVM_TCP_RX_SYNACK);
+        cfg->synack_rx.info.tcp_payload_length = 0;
+
+        /* KEEPALIVE/ACK (TX) */
+        iwl_mvm_build_tcp_packet(
+                mvm, vif, tcp, cfg->keepalive_tx.data, NULL,
+                &cfg->keepalive_tx.info.tcp_pseudo_header_checksum,
+                MVM_TCP_TX_DATA);
+        cfg->keepalive_tx.info.tcp_payload_length =
+                cpu_to_le16(tcp->payload_len);
+        cfg->sequence_number_offset = tcp->payload_seq.offset;
+        /* length must be 0..4, the field is little endian */
+        cfg->sequence_number_length = tcp->payload_seq.len;
+        cfg->initial_sequence_number = cpu_to_le32(tcp->payload_seq.start);
+        cfg->keepalive_interval = cpu_to_le16(tcp->data_interval);
+        if (tcp->payload_tok.len) {
+                cfg->token_offset = tcp->payload_tok.offset;
+                cfg->token_length = tcp->payload_tok.len;
+                cfg->num_tokens =
+                        cpu_to_le16(tcp->tokens_size % tcp->payload_tok.len);
+                memcpy(cfg->tokens, tcp->payload_tok.token_stream,
+                       tcp->tokens_size);
+        } else {
+                /* set tokens to max value to almost never run out */
+                cfg->num_tokens = cpu_to_le16(65535);
+        }
+
+        /* ACK (RX) */
+        iwl_mvm_build_tcp_packet(
+                mvm, vif, tcp, cfg->keepalive_ack_rx.data,
+                cfg->keepalive_ack_rx.rx_mask,
+                &cfg->keepalive_ack_rx.info.tcp_pseudo_header_checksum,
+                MVM_TCP_RX_ACK);
+        cfg->keepalive_ack_rx.info.tcp_payload_length = 0;
+
+        /* WAKEUP (RX) */
+        iwl_mvm_build_tcp_packet(
+                mvm, vif, tcp, cfg->wake_rx.data, cfg->wake_rx.rx_mask,
+                &cfg->wake_rx.info.tcp_pseudo_header_checksum,
+                MVM_TCP_RX_WAKE);
+        cfg->wake_rx.info.tcp_payload_length =
+                cpu_to_le16(tcp->wake_len);
+
+        /* FIN */
+        iwl_mvm_build_tcp_packet(
+                mvm, vif, tcp, cfg->fin_tx.data, NULL,
+                &cfg->fin_tx.info.tcp_pseudo_header_checksum,
+                MVM_TCP_TX_FIN);
+        cfg->fin_tx.info.tcp_payload_length = 0;
+
+        ret = iwl_mvm_send_cmd(mvm, &cmd);
+        kfree(cfg);
+
+        return ret;
+}
+
 struct iwl_d3_iter_data {
         struct iwl_mvm *mvm;
         struct ieee80211_vif *vif;
@@ -640,6 +869,22 @@ int iwl_mvm_suspend(struct ieee80211_hw *hw, struct cfg80211_wowlan *wowlan)
                 d3_cfg_cmd.wakeup_flags |=
                         cpu_to_le32(IWL_WOWLAN_WAKEUP_RF_KILL_DEASSERT);
 
+        if (wowlan->tcp) {
+                /*
+                 * The firmware currently doesn't really look at these, only
+                 * the IWL_WOWLAN_WAKEUP_LINK_CHANGE bit. We have to set that
+                 * reason bit since losing the connection to the AP implies
+                 * losing the TCP connection.
+                 * Set the flags anyway as long as they exist, in case this
+                 * will be changed in the firmware.
+                 */
+                wowlan_config_cmd.wakeup_filter |=
+                        cpu_to_le32(IWL_WOWLAN_WAKEUP_REMOTE_LINK_LOSS |
+                                    IWL_WOWLAN_WAKEUP_REMOTE_SIGNATURE_TABLE |
+                                    IWL_WOWLAN_WAKEUP_REMOTE_WAKEUP_PACKET |
+                                    IWL_WOWLAN_WAKEUP_LINK_CHANGE);
+        }
+
         iwl_mvm_cancel_scan(mvm);
 
         iwl_trans_stop_device(mvm->trans);
@@ -755,6 +1000,10 @@ int iwl_mvm_suspend(struct ieee80211_hw *hw, struct cfg80211_wowlan *wowlan)
         if (ret)
                 goto out;
 
+        ret = iwl_mvm_send_remote_wake_cfg(mvm, vif, wowlan->tcp);
+        if (ret)
+                goto out;
+
         /* must be last -- this switches firmware state */
         ret = iwl_mvm_send_cmd_pdu(mvm, D3_CONFIG_CMD, CMD_SYNC,
                                    sizeof(d3_cfg_cmd), &d3_cfg_cmd);
@@ -874,6 +1123,15 @@ static void iwl_mvm_query_wakeup_reasons(struct iwl_mvm *mvm,
         if (reasons & IWL_WOWLAN_WAKEUP_BY_FOUR_WAY_HANDSHAKE)
                 wakeup.four_way_handshake = true;
 
+        if (reasons & IWL_WOWLAN_WAKEUP_BY_REM_WAKE_LINK_LOSS)
+                wakeup.tcp_connlost = true;
+
+        if (reasons & IWL_WOWLAN_WAKEUP_BY_REM_WAKE_SIGNATURE_TABLE)
+                wakeup.tcp_nomoretokens = true;
+
+        if (reasons & IWL_WOWLAN_WAKEUP_BY_REM_WAKE_WAKEUP_PACKET)
+                wakeup.tcp_match = true;
+
         if (status->wake_packet_bufsize) {
                 int pktsize = le32_to_cpu(status->wake_packet_bufsize);
                 int pktlen = le32_to_cpu(status->wake_packet_length);