/*
* 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, when using firmwares <= v1.3, 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
* firmwares >= 1.4 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 (firmware <= 1.3)
* i2400m_net_erx Called by the RX code when a data frame is
* available (firmware >= 1.4).
* i2400m_netdev_setup Called to setup all the netdev stuff from
* alloc_netdev.
*/
#include <linux/if_arp.h>
#include <linux/slab.h>
#include <linux/netdevice.h>
#include <linux/ethtool.h>
#include <linux/export.h>
#include "i2400m.h"
#define D_SUBMODULE netdev
#include "debug-levels.h"
enum {
/* netdev interface */
/* 20 secs? yep, this is the maximum timeout that the device
* might take to get out of IDLE / negotiate it with the base
* station. We add 1sec for good measure. */
I2400M_TX_TIMEOUT = 21 * HZ,
/*
* Experimentation has determined that, 20 to be a good value
* for minimizing the jitter in the throughput.
*/
I2400M_TX_QLEN = 20,
};
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);
/* Make sure we wait until init is complete... */
mutex_lock(&i2400m->init_mutex);
if (i2400m->updown)
result = 0;
else
result = -EBUSY;
mutex_unlock(&i2400m->init_mutex);
d_fnend(3, dev, "(net_dev %p [i2400m %p]) = %d\n",
net_dev, i2400m, result);
return result;
}
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);
i2400m_net_wake_stop(i2400m);
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 net_device *net_dev = i2400m->wimax_dev.net_dev;
struct device *dev = i2400m_dev(i2400m);
struct sk_buff *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 disappeared!\n");
goto out_put;
}
/* If we have, somehow, lost the connection after this was
* queued, don't do anything; this might be the device got
* reset or just disconnected. */
if (unlikely(!netif_carrier_ok(net_dev)))
goto out_kfree;
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 - resetting\n", result);
i2400m_reset(i2400m, I2400M_RT_BUS);
goto error;
}
result = wait_event_timeout(i2400m->state_wq,
i2400m->state != I2400M_SS_IDLE,
net_dev->watchdog_timeo - HZ/2);
if (result == 0)
result = -ETIMEDOUT;
if (result < 0) {
dev_err(dev, "WAKE&TX: error waiting for device to exit IDLE: "
"%d - resetting\n", result);
i2400m_reset(i2400m, I2400M_RT_BUS);
goto error;
}
msleep(20); /* device still needs some time or it drops it */
result = i2400m_tx(i2400m, skb->data, skb->len, I2400M_PT_DATA);
error:
netif_wake_queue(net_dev);
out_kfree:
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;
}
/*
* Cleanup resources acquired during i2400m_net_wake_tx()
*
* This is called by __i2400m_dev_stop and means we have to make sure
* the workqueue is flushed from any pending work.
*/
void i2400m_net_wake_stop(struct i2400m *i2400m)
{
struct device *dev = i2400m_dev(i2400m);
struct sk_buff *wake_tx_skb;
unsigned long flags;
d_fnstart(3, dev, "(i2400m %p)\n", i2400m);
/*
* See i2400m_hard_start_xmit(), references are taken there and
* here we release them if the packet was still pending.
*/
cancel_work_sync(&i2400m->wake_tx_ws);
spin_lock_irqsave(&i2400m->tx_lock, flags);
wake_tx_skb = i2400m->wake_tx_skb;
i2400m->wake_tx_skb = NULL;
spin_unlock_irqrestore(&i2400m->tx_lock, flags);
if (wake_tx_skb) {
i2400m_put(i2400m);
kfree_skb(wake_tx_skb);
}
d_fnend(3, dev, "(i2400m %p) = void\n", i2400m);
}
/*
* 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 (!i2400m->wake_tx_skb) {
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
netdev_tx_t i2400m_hard_start_xmit(struct sk_buff *skb,
struct net_device *net_dev)
{
struct i2400m *i2400m = net_dev_to_i2400m(net_dev);
struct device *dev = i2400m_dev(i2400m);
int result = -1;
d_fnstart(3, dev, "(skb %p net_dev %p)\n", skb, net_dev);
if (skb_cow_head(skb, 0))
goto drop;
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) {
drop:
net_dev->stats.tx_dropped++;
} else {
net_dev->stats.tx_packets++;
net_dev->stats.tx_bytes += skb->len;
}
dev_kfree_skb(skb);
d_fnend(3, dev, "(skb %p net_dev %p) = %d\n", skb, net_dev, result);
return NETDEV_TX_OK;
}
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++;
}
/*
* Create a fake ethernet header
*
* For emulating an ethernet device, every received IP header has to
* be prefixed with an ethernet header. Fake it with the given
* protocol.
*/
static
void i2400m_rx_fake_eth_header(struct net_device *net_dev,
void *_eth_hdr, __be16 protocol)
{
struct i2400m *i2400m = net_dev_to_i2400m(net_dev);
struct ethhdr *eth_hdr = _eth_hdr;
memcpy(eth_hdr->h_dest, net_dev->dev_addr, sizeof(eth_hdr->h_dest));
memcpy(eth_hdr->h_source, i2400m->src_mac_addr,
sizeof(eth_hdr->h_source));
eth_hdr->h_proto = protocol;
}
/*
* 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
*
* This is only used now for the v1.3 firmware. It will be deprecated
* in >= 2.6.31.
*
* Note that due to firmware limitations, we don't have space to add
* an ethernet header, so we need to copy each packet. Firmware
* versions >= v1.4 fix this [see i2400m_net_erx()].
*
* 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,
cpu_to_be16(ETH_P_IP));
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_net_erx - pass a network packet to the stack (extended version)
*
* @i2400m: device descriptor
* @skb: the skb where the packet is - the skb should be set to point
* at the IP packet; this function will add ethernet headers if
* needed.
* @cs: packet type
*
* This is only used now for firmware >= v1.4. Note it is quite
* similar to i2400m_net_rx() (used only for v1.3 firmware).
*
* 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.
*/
void i2400m_net_erx(struct i2400m *i2400m, struct sk_buff *skb,
enum i2400m_cs cs)
{
struct net_device *net_dev = i2400m->wimax_dev.net_dev;
struct device *dev = i2400m_dev(i2400m);
int protocol;
d_fnstart(2, dev, "(i2400m %p skb %p [%u] cs %d)\n",
i2400m, skb, skb->len, cs);
switch(cs) {
case I2400M_CS_IPV4_0:
case I2400M_CS_IPV4:
protocol = ETH_P_IP;
i2400m_rx_fake_eth_header(i2400m->wimax_dev.net_dev,
skb->data - ETH_HLEN,
cpu_to_be16(ETH_P_IP));
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 += skb->len;
break;
default:
dev_err(dev, "ERX: BUG? CS type %u unsupported\n", cs);
goto error;
}
d_printf(3, dev, "ERX: receiving %d bytes to the network stack\n",
skb->len);
d_dump(4, dev, skb->data, skb->len);
netif_rx_ni(skb); /* see notes in function header */
error:
d_fnend(2, dev, "(i2400m %p skb %p [%u] cs %d) = void\n",
i2400m, skb, skb->len, cs);
}
static const struct net_device_ops i2400m_netdev_ops = {
.ndo_open = i2400m_open,
.ndo_stop = i2400m_stop,
.ndo_start_xmit = i2400m_hard_start_xmit,
.ndo_tx_timeout = i2400m_tx_timeout,
.ndo_change_mtu = i2400m_change_mtu,
};
static void i2400m_get_drvinfo(struct net_device *net_dev,
struct ethtool_drvinfo *info)
{
struct i2400m *i2400m = net_dev_to_i2400m(net_dev);
strlcpy(info->driver, KBUILD_MODNAME, sizeof(info->driver));
strlcpy(info->fw_version, i2400m->fw_name ? : "",
sizeof(info->fw_version));
if (net_dev->dev.parent)
strlcpy(info->bus_info, dev_name(net_dev->dev.parent),
sizeof(info->bus_info));
}
static const struct ethtool_ops i2400m_ethtool_ops = {
.get_drvinfo = i2400m_get_drvinfo,
.get_link = ethtool_op_get_link,
};
/**
* 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->netdev_ops = &i2400m_netdev_ops;
net_dev->ethtool_ops = &i2400m_ethtool_ops;
d_fnend(3, NULL, "(net_dev %p) = void\n", net_dev);
}
EXPORT_SYMBOL_GPL(i2400m_netdev_setup);