diff options
Diffstat (limited to 'drivers/net/wimax/i2400m/netdev.c')
| -rw-r--r-- | drivers/net/wimax/i2400m/netdev.c | 524 |
1 files changed, 524 insertions, 0 deletions
diff --git a/drivers/net/wimax/i2400m/netdev.c b/drivers/net/wimax/i2400m/netdev.c new file mode 100644 index 00000000000..63fe708e8a3 --- /dev/null +++ b/drivers/net/wimax/i2400m/netdev.c @@ -0,0 +1,524 @@ +/* + * Intel Wireless WiMAX Connection 2400m + * Glue with the networking stack + * + * + * Copyright (C) 2007 Intel Corporation <linux-wimax@intel.com> + * Yanir Lubetkin <yanirx.lubetkin@intel.com> + * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License version + * 2 as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA + * 02110-1301, USA. + * + * + * This implements an ethernet device for the i2400m. + * + * We fake being an ethernet device to simplify the support from user + * space and from the other side. The world is (sadly) configured to + * take in only Ethernet devices... + * + * Because of this, currently there is an copy-each-rxed-packet + * overhead on the RX path. Each IP packet has to be reallocated to + * add an ethernet header (as there is no space in what we get from + * the device). This is a known drawback and coming versions of the + * device's firmware are being changed to add header space that can be + * used to insert the ethernet header without having to reallocate and + * copy. + * + * TX error handling is tricky; because we have to FIFO/queue the + * buffers for transmission (as the hardware likes it aggregated), we + * just give the skb to the TX subsystem and by the time it is + * transmitted, we have long forgotten about it. So we just don't care + * too much about it. + * + * Note that when the device is in idle mode with the basestation, we + * need to negotiate coming back up online. That involves negotiation + * and possible user space interaction. Thus, we defer to a workqueue + * to do all that. By default, we only queue a single packet and drop + * the rest, as potentially the time to go back from idle to normal is + * long. + * + * ROADMAP + * + * i2400m_open Called on ifconfig up + * i2400m_stop Called on ifconfig down + * + * i2400m_hard_start_xmit Called by the network stack to send a packet + * i2400m_net_wake_tx Wake up device from basestation-IDLE & TX + * i2400m_wake_tx_work + * i2400m_cmd_exit_idle + * i2400m_tx + * i2400m_net_tx TX a data frame + * i2400m_tx + * + * i2400m_change_mtu Called on ifconfig mtu XXX + * + * i2400m_tx_timeout Called when the device times out + * + * i2400m_net_rx Called by the RX code when a data frame is + * available. + * i2400m_netdev_setup Called to setup all the netdev stuff from + * alloc_netdev. + */ +#include <linux/if_arp.h> +#include <linux/netdevice.h> +#include "i2400m.h" + + +#define D_SUBMODULE netdev +#include "debug-levels.h" + +enum { +/* netdev interface */ + /* + * Out of NWG spec (R1_v1.2.2), 3.3.3 ASN Bearer Plane MTU Size + * + * The MTU is 1400 or less + */ + I2400M_MAX_MTU = 1400, + I2400M_TX_TIMEOUT = HZ, + I2400M_TX_QLEN = 5, +}; + + +static +int i2400m_open(struct net_device *net_dev) +{ + int result; + struct i2400m *i2400m = net_dev_to_i2400m(net_dev); + struct device *dev = i2400m_dev(i2400m); + + d_fnstart(3, dev, "(net_dev %p [i2400m %p])\n", net_dev, i2400m); + if (i2400m->ready == 0) { + dev_err(dev, "Device is still initializing\n"); + result = -EBUSY; + } else + result = 0; + d_fnend(3, dev, "(net_dev %p [i2400m %p]) = %d\n", + net_dev, i2400m, result); + return result; +} + + +/* + * + * On kernel versions where cancel_work_sync() didn't return anything, + * we rely on wake_tx_skb() being non-NULL. + */ +static +int i2400m_stop(struct net_device *net_dev) +{ + struct i2400m *i2400m = net_dev_to_i2400m(net_dev); + struct device *dev = i2400m_dev(i2400m); + + d_fnstart(3, dev, "(net_dev %p [i2400m %p])\n", net_dev, i2400m); + /* See i2400m_hard_start_xmit(), references are taken there + * and here we release them if the work was still + * pending. Note we can't differentiate work not pending vs + * never scheduled, so the NULL check does that. */ + if (cancel_work_sync(&i2400m->wake_tx_ws) == 0 + && i2400m->wake_tx_skb != NULL) { + unsigned long flags; + struct sk_buff *wake_tx_skb; + spin_lock_irqsave(&i2400m->tx_lock, flags); + wake_tx_skb = i2400m->wake_tx_skb; /* compat help */ + i2400m->wake_tx_skb = NULL; /* compat help */ + spin_unlock_irqrestore(&i2400m->tx_lock, flags); + i2400m_put(i2400m); + kfree_skb(wake_tx_skb); + } + d_fnend(3, dev, "(net_dev %p [i2400m %p]) = 0\n", net_dev, i2400m); + return 0; +} + + +/* + * Wake up the device and transmit a held SKB, then restart the net queue + * + * When the device goes into basestation-idle mode, we need to tell it + * to exit that mode; it will negotiate with the base station, user + * space may have to intervene to rehandshake crypto and then tell us + * when it is ready to transmit the packet we have "queued". Still we + * need to give it sometime after it reports being ok. + * + * On error, there is not much we can do. If the error was on TX, we + * still wake the queue up to see if the next packet will be luckier. + * + * If _cmd_exit_idle() fails...well, it could be many things; most + * commonly it is that something else took the device out of IDLE mode + * (for example, the base station). In that case we get an -EILSEQ and + * we are just going to ignore that one. If the device is back to + * connected, then fine -- if it is someother state, the packet will + * be dropped anyway. + */ +void i2400m_wake_tx_work(struct work_struct *ws) +{ + int result; + struct i2400m *i2400m = container_of(ws, struct i2400m, wake_tx_ws); + struct device *dev = i2400m_dev(i2400m); + struct sk_buff *skb = i2400m->wake_tx_skb; + unsigned long flags; + + spin_lock_irqsave(&i2400m->tx_lock, flags); + skb = i2400m->wake_tx_skb; + i2400m->wake_tx_skb = NULL; + spin_unlock_irqrestore(&i2400m->tx_lock, flags); + + d_fnstart(3, dev, "(ws %p i2400m %p skb %p)\n", ws, i2400m, skb); + result = -EINVAL; + if (skb == NULL) { + dev_err(dev, "WAKE&TX: skb dissapeared!\n"); + goto out_put; + } + result = i2400m_cmd_exit_idle(i2400m); + if (result == -EILSEQ) + result = 0; + if (result < 0) { + dev_err(dev, "WAKE&TX: device didn't get out of idle: " + "%d\n", result); + goto error; + } + result = wait_event_timeout(i2400m->state_wq, + i2400m->state != I2400M_SS_IDLE, 5 * HZ); + if (result == 0) + result = -ETIMEDOUT; + if (result < 0) { + dev_err(dev, "WAKE&TX: error waiting for device to exit IDLE: " + "%d\n", result); + goto error; + } + msleep(20); /* device still needs some time or it drops it */ + result = i2400m_tx(i2400m, skb->data, skb->len, I2400M_PT_DATA); + netif_wake_queue(i2400m->wimax_dev.net_dev); +error: + kfree_skb(skb); /* refcount transferred by _hard_start_xmit() */ +out_put: + i2400m_put(i2400m); + d_fnend(3, dev, "(ws %p i2400m %p skb %p) = void [%d]\n", + ws, i2400m, skb, result); +} + + +/* + * Prepare the data payload TX header + * + * The i2400m expects a 4 byte header in front of a data packet. + * + * Because we pretend to be an ethernet device, this packet comes with + * an ethernet header. Pull it and push our header. + */ +static +void i2400m_tx_prep_header(struct sk_buff *skb) +{ + struct i2400m_pl_data_hdr *pl_hdr; + skb_pull(skb, ETH_HLEN); + pl_hdr = (struct i2400m_pl_data_hdr *) skb_push(skb, sizeof(*pl_hdr)); + pl_hdr->reserved = 0; +} + + +/* + * TX an skb to an idle device + * + * When the device is in basestation-idle mode, we need to wake it up + * and then TX. So we queue a work_struct for doing so. + * + * We need to get an extra ref for the skb (so it is not dropped), as + * well as be careful not to queue more than one request (won't help + * at all). If more than one request comes or there are errors, we + * just drop the packets (see i2400m_hard_start_xmit()). + */ +static +int i2400m_net_wake_tx(struct i2400m *i2400m, struct net_device *net_dev, + struct sk_buff *skb) +{ + int result; + struct device *dev = i2400m_dev(i2400m); + unsigned long flags; + + d_fnstart(3, dev, "(skb %p net_dev %p)\n", skb, net_dev); + if (net_ratelimit()) { + d_printf(3, dev, "WAKE&NETTX: " + "skb %p sending %d bytes to radio\n", + skb, skb->len); + d_dump(4, dev, skb->data, skb->len); + } + /* We hold a ref count for i2400m and skb, so when + * stopping() the device, we need to cancel that work + * and if pending, release those resources. */ + result = 0; + spin_lock_irqsave(&i2400m->tx_lock, flags); + if (!work_pending(&i2400m->wake_tx_ws)) { + netif_stop_queue(net_dev); + i2400m_get(i2400m); + i2400m->wake_tx_skb = skb_get(skb); /* transfer ref count */ + i2400m_tx_prep_header(skb); + result = schedule_work(&i2400m->wake_tx_ws); + WARN_ON(result == 0); + } + spin_unlock_irqrestore(&i2400m->tx_lock, flags); + if (result == 0) { + /* Yes, this happens even if we stopped the + * queue -- blame the queue disciplines that + * queue without looking -- I guess there is a reason + * for that. */ + if (net_ratelimit()) + d_printf(1, dev, "NETTX: device exiting idle, " + "dropping skb %p, queue running %d\n", + skb, netif_queue_stopped(net_dev)); + result = -EBUSY; + } + d_fnend(3, dev, "(skb %p net_dev %p) = %d\n", skb, net_dev, result); + return result; +} + + +/* + * Transmit a packet to the base station on behalf of the network stack. + * + * Returns: 0 if ok, < 0 errno code on error. + * + * We need to pull the ethernet header and add the hardware header, + * which is currently set to all zeroes and reserved. + */ +static +int i2400m_net_tx(struct i2400m *i2400m, struct net_device *net_dev, + struct sk_buff *skb) +{ + int result; + struct device *dev = i2400m_dev(i2400m); + + d_fnstart(3, dev, "(i2400m %p net_dev %p skb %p)\n", + i2400m, net_dev, skb); + /* FIXME: check eth hdr, only IPv4 is routed by the device as of now */ + net_dev->trans_start = jiffies; + i2400m_tx_prep_header(skb); + d_printf(3, dev, "NETTX: skb %p sending %d bytes to radio\n", + skb, skb->len); + d_dump(4, dev, skb->data, skb->len); + result = i2400m_tx(i2400m, skb->data, skb->len, I2400M_PT_DATA); + d_fnend(3, dev, "(i2400m %p net_dev %p skb %p) = %d\n", + i2400m, net_dev, skb, result); + return result; +} + + +/* + * Transmit a packet to the base station on behalf of the network stack + * + * + * Returns: NETDEV_TX_OK (always, even in case of error) + * + * In case of error, we just drop it. Reasons: + * + * - we add a hw header to each skb, and if the network stack + * retries, we have no way to know if that skb has it or not. + * + * - network protocols have their own drop-recovery mechanisms + * + * - there is not much else we can do + * + * If the device is idle, we need to wake it up; that is an operation + * that will sleep. See i2400m_net_wake_tx() for details. + */ +static +int i2400m_hard_start_xmit(struct sk_buff *skb, + struct net_device *net_dev) +{ + int result; + struct i2400m *i2400m = net_dev_to_i2400m(net_dev); + struct device *dev = i2400m_dev(i2400m); + + d_fnstart(3, dev, "(skb %p net_dev %p)\n", skb, net_dev); + if (i2400m->state == I2400M_SS_IDLE) + result = i2400m_net_wake_tx(i2400m, net_dev, skb); + else + result = i2400m_net_tx(i2400m, net_dev, skb); + if (result < 0) + net_dev->stats.tx_dropped++; + else { + net_dev->stats.tx_packets++; + net_dev->stats.tx_bytes += skb->len; + } + kfree_skb(skb); + result = NETDEV_TX_OK; + d_fnend(3, dev, "(skb %p net_dev %p) = %d\n", skb, net_dev, result); + return result; +} + + +static +int i2400m_change_mtu(struct net_device *net_dev, int new_mtu) +{ + int result; + struct i2400m *i2400m = net_dev_to_i2400m(net_dev); + struct device *dev = i2400m_dev(i2400m); + + if (new_mtu >= I2400M_MAX_MTU) { + dev_err(dev, "Cannot change MTU to %d (max is %d)\n", + new_mtu, I2400M_MAX_MTU); + result = -EINVAL; + } else { + net_dev->mtu = new_mtu; + result = 0; + } + return result; +} + + +static +void i2400m_tx_timeout(struct net_device *net_dev) +{ + /* + * We might want to kick the device + * + * There is not much we can do though, as the device requires + * that we send the data aggregated. By the time we receive + * this, there might be data pending to be sent or not... + */ + net_dev->stats.tx_errors++; + return; +} + + +/* + * Create a fake ethernet header + * + * For emulating an ethernet device, every received IP header has to + * be prefixed with an ethernet header. + * + * What we receive has (potentially) many IP packets concatenated with + * no ETH_HLEN bytes prefixed. Thus there is no space for an eth + * header. + * + * We would have to reallocate or do ugly fragment tricks in order to + * add it. + * + * But what we do is use the header space of the RX transaction + * (*msg_hdr) as we don't need it anymore; then we'll point all the + * data skbs there, as they share the same backing store. + * + * We only support IPv4 for v3 firmware. + */ +static +void i2400m_rx_fake_eth_header(struct net_device *net_dev, + void *_eth_hdr) +{ + struct ethhdr *eth_hdr = _eth_hdr; + + memcpy(eth_hdr->h_dest, net_dev->dev_addr, sizeof(eth_hdr->h_dest)); + memset(eth_hdr->h_source, 0, sizeof(eth_hdr->h_dest)); + eth_hdr->h_proto = __constant_cpu_to_be16(ETH_P_IP); +} + + +/* + * i2400m_net_rx - pass a network packet to the stack + * + * @i2400m: device instance + * @skb_rx: the skb where the buffer pointed to by @buf is + * @i: 1 if payload is the only one + * @buf: pointer to the buffer containing the data + * @len: buffer's length + * + * We just clone the skb and set it up so that it's skb->data pointer + * points to "buf" and it's length. + * + * Note that if the payload is the last (or the only one) in a + * multi-payload message, we don't clone the SKB but just reuse it. + * + * This function is normally run from a thread context. However, we + * still use netif_rx() instead of netif_receive_skb() as was + * recommended in the mailing list. Reason is in some stress tests + * when sending/receiving a lot of data we seem to hit a softlock in + * the kernel's TCP implementation [aroudn tcp_delay_timer()]. Using + * netif_rx() took care of the issue. + * + * This is, of course, still open to do more research on why running + * with netif_receive_skb() hits this softlock. FIXME. + * + * FIXME: currently we don't do any efforts at distinguishing if what + * we got was an IPv4 or IPv6 header, to setup the protocol field + * correctly. + */ +void i2400m_net_rx(struct i2400m *i2400m, struct sk_buff *skb_rx, + unsigned i, const void *buf, int buf_len) +{ + struct net_device *net_dev = i2400m->wimax_dev.net_dev; + struct device *dev = i2400m_dev(i2400m); + struct sk_buff *skb; + + d_fnstart(2, dev, "(i2400m %p buf %p buf_len %d)\n", + i2400m, buf, buf_len); + if (i) { + skb = skb_get(skb_rx); + d_printf(2, dev, "RX: reusing first payload skb %p\n", skb); + skb_pull(skb, buf - (void *) skb->data); + skb_trim(skb, (void *) skb_end_pointer(skb) - buf); + } else { + /* Yes, this is bad -- a lot of overhead -- see + * comments at the top of the file */ + skb = __netdev_alloc_skb(net_dev, buf_len, GFP_KERNEL); + if (skb == NULL) { + dev_err(dev, "NETRX: no memory to realloc skb\n"); + net_dev->stats.rx_dropped++; + goto error_skb_realloc; + } + memcpy(skb_put(skb, buf_len), buf, buf_len); + } + i2400m_rx_fake_eth_header(i2400m->wimax_dev.net_dev, + skb->data - ETH_HLEN); + skb_set_mac_header(skb, -ETH_HLEN); + skb->dev = i2400m->wimax_dev.net_dev; + skb->protocol = htons(ETH_P_IP); + net_dev->stats.rx_packets++; + net_dev->stats.rx_bytes += buf_len; + d_printf(3, dev, "NETRX: receiving %d bytes to network stack\n", + buf_len); + d_dump(4, dev, buf, buf_len); + netif_rx_ni(skb); /* see notes in function header */ +error_skb_realloc: + d_fnend(2, dev, "(i2400m %p buf %p buf_len %d) = void\n", + i2400m, buf, buf_len); +} + + +/** + * i2400m_netdev_setup - Setup setup @net_dev's i2400m private data + * + * Called by alloc_netdev() + */ +void i2400m_netdev_setup(struct net_device *net_dev) +{ + d_fnstart(3, NULL, "(net_dev %p)\n", net_dev); + ether_setup(net_dev); + net_dev->mtu = I2400M_MAX_MTU; + net_dev->tx_queue_len = I2400M_TX_QLEN; + net_dev->features = + NETIF_F_VLAN_CHALLENGED + | NETIF_F_HIGHDMA; + net_dev->flags = + IFF_NOARP /* i2400m is apure IP device */ + & (~IFF_BROADCAST /* i2400m is P2P */ + & ~IFF_MULTICAST); + net_dev->watchdog_timeo = I2400M_TX_TIMEOUT; + net_dev->open = i2400m_open; + net_dev->stop = i2400m_stop; + net_dev->hard_start_xmit = i2400m_hard_start_xmit; + net_dev->change_mtu = i2400m_change_mtu; + net_dev->tx_timeout = i2400m_tx_timeout; + d_fnend(3, NULL, "(net_dev %p) = void\n", net_dev); +} +EXPORT_SYMBOL_GPL(i2400m_netdev_setup); + |