There are several exit path from the PCI probe function.
Some of them, that are taken in case of errors, forget to set the "err"
variable, that is returned by the probe function.
This can lead to the kernel thinking the probe function succeeds while it
didn't, and this in turn causes extra calls to the "remove" function.

This patch fix this problem by ensuring "err" variable is assigned to a proper
non-zero value in each exit path.
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

All boards supported by this driver could work using PIO or MMIO for accessing
registers.
This driver tries to access HW by using MMIO, and, if this fails for somewhat
reason, the driver tries to fall back to PIO mode.

MMIO-mode is straightforward on all boards.
PIO-mode is straightforward on rtl8180 only.

On rtl8185 and rtl8187se boards not all registers are directly available in PIO
mode (they are paged).

On rtl8185 there are two pages and it is known how to switch page.
PIO mode works, except for only one access to a register out of default page,
recently added by me in the initialization code with patch:
rtl818x_pci: Fix rtl8185 excessive IFS after CTS-to-self
This can be easily fixed to work in both cases (MMIO and PIO).

On rtl8187se, for a number of reasons, there is much more work to do to fix PIO
access.
PIO access is currently broken on rtl8187se, and it never worked.

This patch fixes the said register write for rtl8185 and makes the driver to
fail cleanly if PIO mode is attempted with rtl8187se boards.

While doing this, I converted also a couple of printk(KERN_ERR) to dev_err(), in
order to make checkpatch happy.
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

Currently the driver configures mac80211 to provide two rates for each TX frame:
One initial rate and one alternate fallback rate, each one with its retry count.

HW does not support fully this: rtl8180 doesn't have support for rate scaling at
all, and rtl8185/rtl8187SE supports it in a way that does not fit with mac80211:
The HW does automatically fall back to the next lower rate, and only a lower
limit can be specified, so the HW may TX also on rates in between the two rates
specified by mac80211.  Furthermore only the total TX retry count can be
specified for each packet, while the number of TX attempts before scaling rate
can be configured only globally (not per each packet).

Currently the driver sets the HW auto rate fallback mechanism to quickly scale
rate after a couple of retries, and it uses the alternate rate requested by
mac80211 as fallback limit rate (and it does this even wrongly).

The HW indeed will behave differently than what mac80211 mandates, that is
probably undesirable, and the reported TX retry count may not refer to what
mac80211 thinks, and this could fool mac80211.

This patch makes the driver to declare to mac80211 to support only one rate
configuration for each packet, and it does disable the HW auto rate fallback
mechanism, relying only on SW and letting mac80211 to do all by itself.

This should ensure correct operation and fairness respect to mac80211.
Indeed here tests with iperf do not show significant performance differences.
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

HW is programmed with wrong retry count value for TX:

Mac80211 passes to driver the number of times the TX should be attempted.
The HW, instead, wants the number of time the TX should be retried if it fails
the first time (assuming we have to TX it at least one time).

This patch correct this.
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

Rtl8187se support has been added to the rtl818x_pci driver by extracting a lot
of information from a rtl8187se Linux staging driver included in the kernel at
the time rtl8187se support was added.
The rtl818x_pci main file has a comment that advertises this.

Recently this staging driver has been removed from the kernel, but I still feel
it can be useful as "reference" code (in case of bugs, or to implement
improvements in rtl818x_pci driver).

This one-line patch adds a comment in rtl818x_pci driver to point people
searching for that "reference code" to the last kernel version still containing
it (3.14).
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

Measuring time between _end_ of CTS-to-self and _end_ of datapacket (with a
prism54 board and mac80211 hacked to let the MAC timestamp stay untouched in the
radiotap header) resulted in about 300uS, while the datapacket itself should be
by far shorter (less than 100uS) and IFS should be SIFS (10uS).
This measure was confirmed whith a scope: about 250uS IFS has been seen between
the two packets.

This situation causes the CTS-to-self protection mechanism to work incorrectly
due to the NAV expiring during, or even before beginning, the packet
transmission, and it also causes the performances to be anyway reduced due to
time waste.

This problem has been seen at every packet TXed with CTS-to-self enabled on
rtl8185 board.
rtl8187se seems not affected (and rtl8180, being a 802.11b card, does not have
CTS-to-self mechaninsm).

This patch fixes this by adding a magic register write, making the board wait
for correct SIFS after CTS-to-self packet.
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

BSSID register was written with six byte-writes.
It seems that, similarly to what happens with MAC registers, they needs to be
written with one 16-bit and one 32-bit writes, otherwise the write does not work.

The byte write didn't work only on my rtl8185, while it worked on rtl8180 and
rtl8187se, BTW since there are probably a number of different ASIC revisions out
of there, I let the change to affect all cards.
It shouldn't hurt anyway.
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

RX descriptor data must be read only if the descriptor has been fully
updated by HW.
There is a "ownership" flag in the descriptor itself to test this.

The driver code contains a read for the "ownership" flag and, after
it, other read access for descriptor data.

This is in DMA coherent memory, that is _not_ guaranteed to be immune
to instruction reordering, thus it is possible that the descriptor
data is read _before_ the "ownership" flag.

This can theoretically lead to a DMA/CPU race that may end up with the
driver reading the data when it is still not valid, and the "ownership"
bit just after enough time that the HW make the whole descriptor valid.
The driver will in this case believe the data is valid, but it will use
the invalid data read earlier.

In order to avoid this, this patch adds a rmb() to force the "ownership"
bit read to be issued before other descriptor data reads are attempted.
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

This patch makes the driver report signal information for rtl8185
boards using dBm instead of unspecified unit.
Rtl8180 remains untouched.

I did some tests to confirm the correctness of the measure performed
by the board and it seems reasonably correct.

The test setup has been made by connecting an AP with coax and
RF attenuators to the card antenna port.

In order to get a reference measure I tried with several cards with
different chipset I own. I found that many gave different results, and
I finally selected two cards that gave me consistent results to use
as reference: AR9271 and Prism54-usb (isl3887 with Frisbee radio).

Using this references I compared the RSSI information with my rtl8185
and I repeated tests with three different attenuation values, increasing
attenuation by 10dB each step.
I made only relative measures, making NO assumption about source power.

CCK measures seem very close to my references, OFDM are a little bit
less precise but, considering that these cards are not measuring
instrumentation, IMHO this is still fairly good.

CCK measures (1Mbps beacons)

 ATTENUATOR 1
p54usb:    -58dBm
ath9k_htc: -59dBm
rtl8185:   -59dBm

 ATTENUATOR 2
p54usb:    -67dBm
ath9k_htc: -68dBm
rtl8185:   -70dBm

 ATTENUATOR 3
p54usb:    -78dBm
ath9k_htc: -79dBm
rtl8185:   -79dBm

OFDM measures (54Mbps ping)

 ATTENUATOR 1
p54usb:    -58dBm
ath9k_htc: -57dBm
rtl8185:   -62dBm

 ATTENUATOR 2
p54usb:    -68dBm
rtl8185:   -71dBm
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

remove the if-else chains and use switch-case to make code more
readable and avoiding long lines that broke in several lines
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

CTS protection was not working properly because the HW still need
RTS flag to be asserted, and it need also RTS rate field to be
set with CTS-to-self rate and RTS duration field to be filled with
CTS-to-self duration.

This patch makes the driver to do this.
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

This patch make it possible to mac80211 to know whether a frame
has been received with short preamble.

It simply checks for the "splcp" flag in the RX status
descriptor, and eventually set RX_FLAG_SHORTPRE in mac80211
rx status structure.
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

HW should never attempt to perform DMA for unused queues.
For rtl8187se this is ensured by setting a dedicated register at
init time, before enabling TX.

In rtl8180/5 the register is only written at the first TX (because
in rtl8180/5 it serves also to kick DMA for used queues).
This should be enough, but it's worth to add a register write at
init time, before enabling TX.
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

When preparing the bitfield to write to HW register, the high-priority
queue error interrupt bit is set two times, and the beacon queue
TX-OK interrupt is not enabled.

Currently this have no functional impact because the high-priority
queue is not used at all, and the beacon queue is not used yet.

This patch removes high-priority queue bits and it adds the
beacon queue missing bit.
It removes also the management queue bits because it is not used.

This was found by static code analyzer.
Reported-by: NFengguang Wu <fengguang.wu@intel.com>
Reported-by: NJulia Lawall <julia.lawall@lip6.fr>
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

Finally make rtl8187se works (hopefylly).
This patch adds PCI ID for rtl8187, updates copyright notes and
updates MODULE_DESCRIPTION.
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

Add case to detect the rtl8187se card and its RF frontend.
In this case set also accordingly mac80211 queue number.
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

Introduce a new function to configure AC parameters for TX queues
on rtl8187se cards, and hook it onto mac80211 in order to enable
WMM support.
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

MSR register for rtl8187se must always have ENEDCA flag set.
Write it accordingly when updated on BSS change.
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

This patch adds ERP configuration support for rtl8187se to the
existing ERP configuration function.
It needs a different register offset and it must not apply
rtl8185 workaround.
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

This patch adds few functions that initializes extra stuff that
is present only in rtl8187se HW, and it modify the existing
HW initialization function where necessary
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

This patch introduce new RF code for rtl8225 zebra v4 radio
frontend.

This code contains a lot of black magic and it can work probably
only with the radio embdedded in the rtl8187se single-chip.
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

rtl8180 has one register for analog converters setting ,rtl8185 has
two and rtl8187se has three.
Setting those registers require more than a simple write, and for
one of them a function is already provided.
This patch introduces functions for the other two.
rtl8187se will use them. rtl8185 doesen't yet, but should
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

rtl8187se nees extra parameters to be read from the eeprom.
This patch adds support for it
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

configuration of carbus-related registers is different for
rtl8187se.
Introduce a dedicated function that does it for all cards in the
proper way
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

This patch adds tx queue mapping for rtl8187se and a long comment
block about their usages.
It adapts the TX function to use that map and it sets properly
the TX descriptor rtl8187se-only fields
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

MAR registers are not present in rtl8187se, and attempting to
write to them must be avoided
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

This patch introduces two dedicated functions for enabling and
disabling ints.
Support for rtl8187se is also added to them
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

rtl8187se has more queues and different ISR flags.
This patch adds a separated ISR handler for rtl8187se
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

Currently RX status descriptor and RX command descriptor are
represented using the same struct type.
This patch splits this by introducing different types for
rx status and command descriptor.
Doing this make it possible to handle rtl8187se RX descriptors
easier.
This patch do also this by adding specific cases where needed.
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

Basic rate configuration is a bit different for rtl8187se.
Adding this also fixes the gcc warning introduced in last patch
about unhandled case in switch.
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

On currently supported HW there are four TX queues (three for normal
packets and one for beacons).

The driver uses just one TX queue, and declare to mac80211 to
support just one queue, but it allocates coherent memory for all
queues.
Furthermore the TX is code is written assumimg four queues exists,
and even if we decide to enable more queues in future, its mapping
rule to mac80211 is fixed.

This means we have memory waste on rtl8180/rtl8185, and we have also
not enough flexibility to add support for boards (rtl8187se) that
will use more queues.

This patch changes things in order to allocate coherent memory only
for the queues effectively used and it make it possible to specify
how to map hardware queues on mac80211 queues, that will be used
by rtl8187se code as soon it will be merged.

Note: even if the beacon queue is currently unused, this should
change, so I kept it.
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

Hw DMA registers are written in rtl8180_init_hw function.
They are also written again just after calling rtl8180_init_hw.
There is no point in doing this twice.

Remove those redundant register writes from rtl8180_start.
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

Eeprom read operations are mixed in the probe function.
Make the code more readable and clean by extracting this code and
moving it in a dedicated function.

The variable eeprom_cck_table_adr, now useless, is here because
it will be needed for rtl8187se support, that I hope to add soon.
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

SLOT, SIFS, DIFS, EIFS, CW and ACK-timeout registers are set in an
RF-code callback and their values are fixed.

This patch moves this off the rf-code, and introduce two new functions
that calculate these values depending by slot time and CW values
requested by mac80211.

This seems to improve performances on my setup.

Currently the ack and slot time values could be stored in a local
variable, but this patch stores it in the driver "priv" structure
because it will be useful for rtl8187se support that will be added
(hopefully) soon.
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

Basic rates setting is done with hardcoded register write with
fixed settings.

This patch introduces a new function that makes it possible to
configure basic rates and it add a check for mac80211
BSS_CHANGED_BASIC_RATES flag in order to eventually invoke that
function when needed.
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

Currently a "r8185" integer variable is used as a boolean flag to
indicate whether the card is a rtl8185 or not.
Since now the driver supports only rtl8185 and rtl8180 cards, if
"r8185" variable is zero then the card is implicitly assumed to
be a rtl8180.

Now I'm preparing to add support for a third card type (rtl8187se).

This patch changes the "r8185" flag with an enum variable to
explicitly indicate which card type we have.

I'm submitting this this patch now, even if I still have to submit
other patches that not pertain with rtl8187se support, because
IMHO it's not worth rebasing them on the current code, using r8185
flag, and then changing them back again nearly immediately.
BTW if someone feels I really should do this, please tell me..
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

The TX descriptors are consumed by the HW using DMA.
Even if in the driver code the TX descriptor writes appears before
the HW "dma kick" register writes, the CPU may reorder them.

If this happens, the TX may not happen at all becase the "valid"
descriptor flag may have not been set yet.

This patch adds a write memory barrier to ensures the TX
descriptor is written before writing to the HW "dma kick" register.
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

The TX descriptors are consumed by the HW using DMA.
Even if in the driver code the memory write that sets the "valid"
flag appears after all other writes, the CPU may reorder writes,
causing the HW to consider as valid a not-fully-written yet
descriptor.

This may cause HW incorrect behaviour.

This can happen because (AFAIK) the HW may attempt DMA
asynchronously without waiting to be kicked by the following
register write.

This patch adds a write memory barrier to enforce writes ordering.
Reported-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

Certain HW options (TX packet retry count, CW configuration and
TX power configuration) can be specified in both the TX packet
descriptor and also into HW "global" registers.

The HW is thus configured to honour the global register or the
TX descriptor field depending by the case.

This patch adds few comments that hopefully clarify in which cases
the driver uses one method and in which cases it uses the other.
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

During driver initialization, some skbs are preallocated for RX.
Currenly if the allocation fails, the driver's allocation routine
exits immediatly but it will return zero (success) anyway.

In this way the driver will continue initialization with buggy
pointers around.

This patch makes the driver's allocation routine to return
an error value and to print a complaint message when skb allocation
fails.
In this way its caller will not go further, avoinding the driver to
successfully load, and preventing dereferencing buggy pointers.

An hint is thus printed about why the driver failed.
Signed-off-by: NAndrea Merello <andrea.merello@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>