When instructing the microcode to use just a single
chain when we have power saving enabled, we should
also tell the AP that we are doing SM powersave.
However, using a single chain doesn't actually have
any power saving advantage while idle -- measurements
show that the power consumption is no different when
using one vs. two or three chains.

Therefore, always instruct the microcode to use all
chains.
Signed-off-by: NJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

We never have four chains, but let's fix the typo
while we noticed it. You count 0, 1, 2, 3, not
0, 1, 2, 4 :)
Signed-off-by: NJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

Today's implementation allow LED to blink based on the traffic
condition. We introduce an additional LED mode that reflects the RF
state.

The supported LED modes after this are:
  IWL_LED_BLINK (current/default) - blink rate based on current Tx/Rx
                                    traffic
  IWL_LED_RF_STATE (new) -
    LED OFF: No power/RF disabled, the LED is emitting no light
    LED ON:  Powered/RF enabled, the LED is emitting light
             in a stable non-flashing state.

In order to provide the flexibility to support different LED
behavior per user/system preference we add "led_mode" iwlcore module
parameter.
Signed-off-by: NWey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

Update PCI Subsystem ID for 60x0 series based on HW SKU. Adding new SKU
for "ABG" and "BG" only devices.
Signed-off-by: NWey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

Update PCI Subsystem ID for 1000 series based on HW SKU. Adding new SKU
for "BG" only devices.
Signed-off-by: NWey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

In order for uCode to select the valid antennas for transmit, driver
need to configure the allowed tx antennas through host command.

The TX_ANT_CONFIGURATION_CMD should be used for 5000 series and up
Signed-off-by: NWey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

Current rate scale algorithm fluctuates between different MIMO modes fairly
rapidly, causing widely varying performance. These fluctuations occur because in
the rate_scale tables for expected throughput the values are not very different
for different modes.

However, when aggregation is turned on and MAC overhead is reduced, the
expected throughput for different MIMO modes grows and different modes have
vastly different performance. Add expected throughput tables for this case.

We also need to keep track of aggregation status per-station, so we add the
"is_agg" field to struct lq_sta.

Also includes cleanup of comments and variable names in/around the affected
code.
Signed-off-by: NDaniel C Halperin <daniel.c.halperin@intel.com>
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

OR-in AMPDU flags rather than assigning them.  This lets the TX status for
aggregated packets be processed by rs_tx_status.
Signed-off-by: NDaniel C Halperin <daniel.c.halperin@intel.com>
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

Cut down on redundant code, reorganize structure, and add/improve comments.
Should contain no functional changes.
Signed-off-by: NDaniel C Halperin <daniel.c.halperin@intel.com>
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

Instead of hardcode module parameter's permissions, use pre-defined.
Signed-off-by: NWey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

Update EEPROM version requirement for 1000 and 6000 series of NIC
for EEPROM version verification.
Signed-off-by: NWey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

Allow user to change protection mechanism for HT between RTS/CTS and
CTS-to-self through sysfs:

Show current protection mechanism for HT
   cat /sys/class/net/wlan0/device/rts_ht_protection

Change protection mechanism for HT (only allowed while not-associated)
CTS-to-self:
   echo 0 > /sys/class/net/wlan0/device/rts_ht_protection
RTS/CTS:
   echo 1 > /sys/class/net/wlan0/device/rts_ht_protection
Signed-off-by: NWey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

When 802.11g was introduced, we had RTS/CTS and CTS-to-Self protection
mechanisms. In an HT Beacon, HT stations use the "Operating Mode" field
in the HT Information Element to determine whether or not to use
protection.

The Operating Mode field has 4 possible settings: 0-3:
Mode 0: If all stations in the BSS are 20/40 MHz HT capable, or if the
BSS is 20/40 MHz capable, or if all stations in the BSS are 20 MHz HT
stations in a 20 MHz BSS
Mode 1: used if there are non-HT stations or APs using the primary or
secondary channels
Mode 2: if only HT stations are associated in the BSS and at least one
20 MHz HT station is associated.
Mode 3: used if one or more non-HT stations are associated in the BSS.

When in operating modes 1 or 3, and the Use_Protection field is 1 in the
Beacon's ERP IE, all HT transmissions must be protected using RTS/CTS or
CTS-to-Self.

By default, CTS-to-self is the preferred protection mechanism for less
overhead and higher throughput; but using the full RTS/CTS will better
protect the inner exchange from interference, especially in
highly-congested environment.

For 6000 series WIFI NIC, RTS/CTS protection mechanism is the
recommended choice for HT traffic based on the HW design.
Signed-off-by: NWey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

The chain settings we currently use in iwlwifi are
rather confusing -- and we also go by the wrong
settings entirely under certain circumstances. To
clean it up, create a new variable in the current
HT config -- single_chain_sufficient -- that tells
us whether we need more than one chain. Calculate
that based on the AP and operating mode (no IBSS
HT implemented -- so no need for multiple chains,
for station mode we use the AP's capabilities).

Additionally, since APs always send disabled SM PS
mode, keeping track of their sm_ps mode isn't very
useful -- doubly not so for our _own_ RX config
since that should depend on our, not the AP's, SM
PS mode.

Finally, document that our configuration of the
number of RX chains used is currently wrong when
in powersave (by adding a comment).

All together this removes the two remaining items
in struct iwl_ht_config that were done wrong there.

For the future, the number of RX chains and some
SM PS handshaking needs to be added to mac80211,
which then needs to tell us, and the new variable
current_ht_config.single_chain_sufficient should
also be calculated by mac80211.
Signed-off-by: NJohannes Berg <johannes@sipsolutions.net>
Acked-by: NDaniel C Halperin <daniel.c.halperin@intel.com>
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

Show version number along with dumping NVM data, the version information
being removed from sysfs, add it back to debugfs to help debugging.
Signed-off-by: NWey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

Daniel Halperin pointed out that the naming
here is rather inconsistent with at least 3
different names being used for one thing in
different contexts. Rename the struct to
iwl_ht_config (rather than iwl_ht_info) and
use ht_conf as a variable for it.
Signed-off-by: NJohannes Berg <johannes@sipsolutions.net>
Acked-by: NDaniel C Halperin <daniel.c.halperin@intel.com>
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

Adjust led blink rate to compensate on a MAC Clock difference on every
HW. Led blink rate analysis showed an average deviation of 0% on 3945,
5% on 4965 HW and 20% on 5000 series and up.
Need to compensate on the led on/off time per HW according to the
deviation to achieve the desired led frequency
The calculation is: (100-averageDeviation)/100 * blinkTime
For code efficiency the calculation will be:
    compensation = (100 - averageDeviation) * 64 / 100
    NewBlinkTime = (compensation * BlinkTime) / 64
Signed-off-by: NWey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

is_ht can be bool instead of u8, and there's
no need to use IWL_CHANNEL_WIDTH_* constants
in supported_chan_width when that could just
be named is_40mhz instead.
Signed-off-by: NJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

Separate set_hw_params() function for 6000
series from 5000/1000 series because:
    1) 6000 series use different set of sensitivity range table
    2) 6000 series has different uCode image size

Also include the new sensitivity parameters needed by sensitivity
algorithm.
Signed-off-by: NWey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

Different NIC has different requirements for configuration. Currently all
5000 series hardware and later share the same configuration function even
though they do not need the same configurations. Fix this by separating the
needed configuration actions for each hardware model.

.5000 series: L1-ASPM H/W bug work-around
              configure radio
              write CSR_HW_IF_CONFIG_REG for uCode use
              work-around for NIC get stuck after early PCIe power off

.1000 series: write CSR_HW_IF_CONFIG_REG for uCode use
              setting digital SVR for 1000 card to 1.32V

.6000 series: configure radio
              write CSR_HW_IF_CONFIG_REG for uCode use
              write CSR_GP_DRIVER_REG to indicate radio sku
Signed-off-by: NWey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

Remove few of the parameters not used and no longer valid in EEPROM.
Signed-off-by: NWey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

Modify LED blink index table to include 1Mbps.
Signed-off-by: NWey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

When hardware or uCode problem occurs driver captures significant
information from device to enable debugging. The format of this information
is different between 3945 and 4965 and later devices, yet currently the
3945 uses the 4965 and later format. Fix this by adding a new library call
that is initialized to the correct formatting routine based on device.

This moves the iwlagn event and error log handling back to iwl-agn.c to
make it part of iwlagn module.

Also remove the 3945 sysfs file that triggers dump of event log - there is
already a debugfs file that can do it for all drivers.
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

Also free the array of command pointers and meta data of each
command buffer when command queue is freed.
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

We keep track of where to write into a buffer by keeping a count of how
much has been written so far. When writing to the buffer we thus take the
buffer pointer and adding the count of what has been written so far.
Keeping track of what has been written so far is done by incrementing
this number every time something is written to the buffer with how much has
been written at that time.

Currently this number is incremented incorrectly when using the
"hex_dump_to_buffer" call to add data to the buffer. Fix this by only
adding what has been added to the buffer in that call instead of what has
been added since beginning of buffer.

Issue was discovered and discussed during testing of
https://bugzilla.redhat.com/show_bug.cgi?id=464598 .

When a user views any of these files they will see something like:

[  179.355202] ------------[ cut here ]------------
[  179.355209] WARNING: at ../lib/vsprintf.c:989 vsnprintf+0x5ec/0x5f0()
[  179.355212] Hardware name: VGN-Z540N
[  179.355213] Modules linked in: i915 drm i2c_algo_bit i2c_core ipv6 acpi_cpufreq cpufreq_userspace cpufreq_powersave cpufreq_ondemand cpufreq_conservative cpufreq_stats freq_table container sbs sbshc arc4 ecb iwlagn iwlcore joydev led_class mac80211 af_packet pcmcia psmouse sony_laptop cfg80211 iTCO_wdt iTCO_vendor_support pcspkr serio_raw rfkill intel_agp video output tpm_infineon tpm tpm_bios button battery yenta_socket rsrc_nonstatic pcmcia_core processor ac evdev ext3 jbd mbcache sr_mod sg cdrom sd_mod ahci libata scsi_mod ehci_hcd uhci_hcd usbcore thermal fan thermal_sys
[  179.355262] Pid: 5449, comm: cat Not tainted 2.6.31-wl-54419-ge881071 #62
[  179.355264] Call Trace:
[  179.355267]  [<ffffffff811ad14c>] ? vsnprintf+0x5ec/0x5f0
[  179.355271]  [<ffffffff81041348>] warn_slowpath_common+0x78/0xd0
[  179.355275]  [<ffffffff810413af>] warn_slowpath_null+0xf/0x20
[  179.355277]  [<ffffffff811ad14c>] vsnprintf+0x5ec/0x5f0
[  179.355280]  [<ffffffff811ad23d>] ? scnprintf+0x5d/0x80
[  179.355283]  [<ffffffff811ad23d>] scnprintf+0x5d/0x80
[  179.355286]  [<ffffffff811aed29>] ? hex_dump_to_buffer+0x189/0x340
[  179.355290]  [<ffffffff810e91d7>] ? __kmalloc+0x207/0x260
[  179.355303]  [<ffffffffa02a02f8>] iwl_dbgfs_nvm_read+0xe8/0x220 [iwlcore]
[  179.355306]  [<ffffffff811a9b62>] ? __up_read+0x92/0xb0
[  179.355310]  [<ffffffff810f0988>] vfs_read+0xc8/0x1a0
[  179.355313]  [<ffffffff810f0b50>] sys_read+0x50/0x90
[  179.355316]  [<ffffffff8100bd6b>] system_call_fastpath+0x16/0x1b
[  179.355319] ---[ end trace 2383d0d5e0752ca0 ]---
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

In some cases firmware can give us bad value of index in transmit
buffers array. This patch add sanity check for such values and return
from processing function instantly when it happens.

https://bugzilla.redhat.com/show_bug.cgi?id=521931

Patch was tested by reporter on iwl5000. I think check can be also
helpful for 4965.
Signed-off-by: NStanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

Replenishment of receive buffers is done in the tasklet handling
received frames as well as in a workqueue. When we are in the tasklet
we cannot sleep and thus attempt atomic skb allocations. It is generally
not a big problem if this fails since iwl_rx_allocate is always followed
by a call to iwl_rx_queue_restock which will queue the work to replenish
the buffers at a time when sleeping is allowed.

We thus add the __GFP_NOWARN to the skb allocation in iwl_rx_allocate to
reduce the noise if such an allocation fails while we still have enough
buffers. We do maintain the warning and the error message when we are low
on buffers to communicate to the user that there is a potential problem with
memory availability on system

This addresses issue reported upstream in thread "iwlagn: order 2 page
allocation failures" in
http://thread.gmane.org/gmane.linux.kernel.wireless.general/39187Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Acked-by: NMel Gorman <mel@csn.ul.ie>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

commit 10c994ca70e8e94bbc85a5bf13de5911ee8de4d2 "iwlwifi: fix remove key
error" fixed an error reported by mac80211 during interface down. The fix
involved changing an async command to synchronous. Unfortunately this was
inside a spinlock section in which we cannot sleep.

Modify the sending of the command back to async. This causes the mac80211
error "mac80211-phy0: failed to remove key (0, ff:ff:ff:ff:ff:ff) from
hardware (-16)." to return. This error is not serious since this occurs
during interface down and the keys will be cleared anyway when ucode is
unloaded. Having this error message is thus less serious than a potential
deadlock introduced when sleeping while holding a spinlock. We will have to
find another fix for that error.

This is a revert of the abovementioned commit.
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

There's a bug in 4965 powersave that appears to
be related to the way it keeps track of its data
during sleep, but we haven't found it yet. Due to
that, using powersave may spontaneously cause the
device to SYSASSERT when transitioning from sleep
to wake. Therefore, disable powersave for 4965,
until (if ever, unfortunately) we can identify
and fix the problem.

Cf. http://bugzilla.intellinuxwireless.org/show_bug.cgi?id=1982
which was closed, but now has re-appeared with
IDLE mode, which probably means we never really
fixed it.
Signed-off-by: NJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

We can not assume antenna "A" is the first valid anttena for
all the NIC. Need to make sure choice the correct antenna based on
h/w configuration for transmit to avoid sending frame on invalid
antenna
Signed-off-by: NWey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

RX handling maintains a few lists that keep track of the RX buffers.
Buffers move from one list to the other as they are used, replenished, and
again made available for usage. In one such instance, when a buffer is used
it enters the "rx_used" list. When buffers are replenished an skb is
attached to the buffer and it is moved to the "rx_free" list. The problem
here is that the buffer is first removed from the "rx_used" list _before_ the
skb is allocated. Thus, if the skb allocation fails this buffer remains
removed from the "rx_used" list and is thus lost for future usage.

Fix this by first allocating the skb before trying to attach it to a list.
We add an additional check to not do this unnecessarily.
Reported-by: NRick Farrington <rickdic@hotmail.com>
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

When we cleaned up the driver to properly tell mac80211 about HT rates
("iwlwifi: use iwl_hwrate_get_mac80211_idx where appropriate"), we broke
internal rate indexing in 2.4 GHz band.
Signed-off-by: NDaniel C Halperin <daniel.c.halperin@intel.com>
Tested-by: NWey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

There's a bug in 4965 powersave that appears to
be related to the way it keeps track of its data
during sleep, but we haven't found it yet. Due to
that, using powersave may spontaneously cause the
device to SYSASSERT when transitioning from sleep
to wake. Therefore, disable powersave for 4965,
until (if ever, unfortunately) we can identify
and fix the problem.

Cf. http://bugzilla.intellinuxwireless.org/show_bug.cgi?id=1982
which was closed, but now has re-appeared with
IDLE mode, which probably means we never really
fixed it.
Signed-off-by: NJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

We can not assume antenna "A" is the first valid anttena for
all the NIC. Need to make sure choice the correct antenna based on
h/w configuration for transmit to avoid sending frame on invalid
antenna
Signed-off-by: NWey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

RX handling maintains a few lists that keep track of the RX buffers.
Buffers move from one list to the other as they are used, replenished, and
again made available for usage. In one such instance, when a buffer is used
it enters the "rx_used" list. When buffers are replenished an skb is
attached to the buffer and it is moved to the "rx_free" list. The problem
here is that the buffer is first removed from the "rx_used" list _before_ the
skb is allocated. Thus, if the skb allocation fails this buffer remains
removed from the "rx_used" list and is thus lost for future usage.

Fix this by first allocating the skb before trying to attach it to a list.
We add an additional check to not do this unnecessarily.
Reported-by: NRick Farrington <rickdic@hotmail.com>
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

When we cleaned up the driver to properly tell mac80211 about HT rates
("iwlwifi: use iwl_hwrate_get_mac80211_idx where appropriate"), we broke
internal rate indexing in 2.4 GHz band.
Signed-off-by: NDaniel C Halperin <daniel.c.halperin@intel.com>
Tested-by: NWey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

Significant literature suggests users use debug flags 0x43fff - this causes
the debug flags to be set that causes information to be printed for every
received frame - including beacons. In the best case it fills up the logs,
at worst it slows driver down and causes failures due to timeouts.

In the RX handler, print debugging only if user requested RX debugging.
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

3945 does not have update_chain_flags defined and because if this we always
see the debug message that does not apply to it. Add a check to be specific
about what is actually happening.
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

Some concerns were raised about the automatic adjustment
of sleep intervals to all the same, potentially high,
value, and I can imagine the hardware behaving better
when we don't ask too much of it.

So let's convert to use a succession of sleep levels
when requesting to go to deeper sleeps (which can only
happen with large DTIM intervals), using the succession
values from power level three, which have the benefit of
also having been tested extensively already.

As a result, the automatic sleep level adjustment will
now be mostly equivalent to power level three, except
for the RX/TX timeouts and possibly using smaller sleep
vectors to account for networking latency.
Signed-off-by: NJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

For HT packets, mac80211 expects the rate_idx to be an MCS number, which is the
lower byte of rate_n_flags.  However, iwl_hwrate_to_plcp_idx takes the MCS
number and reduces it down to the range 0-8 (6 to 60 Mbps), removing the bits
that signify multiply streams, HT40 Duplicate mode, or unequal modulation.
This version is used for various internal purposes through the driver.

Add the function iwl_hwrate_get_mac80211_idx, an alternate version which takes
the rate and the band and returns the mac80211 index (MCS, for HT packets, and
PLCP rate, for legacy packets).
Signed-off-by: NDaniel C Halperin <daniel.c.halperin@intel.com>
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>