ath10k: avoid possible deadlock with scan timeout

This should prevent deadlock predicted by the
following splat:

 ======================================================
 [ INFO: possible circular locking dependency detected ]
 3.17.0-wl-ath+ #67 Not tainted
 -------------------------------------------------------
 kworker/u32:1/7230 is trying to acquire lock:
  (&ar->conf_mutex){+.+.+.}, at: [<ffffffffa040a57d>] ath10k_scan_timeout_work+0x2d/0x50 [ath10k_core]

 but task is already holding lock:
  ((&(&ar->scan.timeout)->work)){+.+...}, at: [<ffffffff8106dae1>] process_one_work+0x151/0x470

 which lock already depends on the new lock.

 the existing dependency chain (in reverse order) is:

 -> #1 ((&(&ar->scan.timeout)->work)){+.+...}:
        [<ffffffff810a12e5>] lock_acquire+0x85/0x100
        [<ffffffff8106cb4d>] flush_work+0x3d/0x270
        [<ffffffff8106e49d>] __cancel_work_timer+0x7d/0x110
        [<ffffffff8106e543>] cancel_delayed_work_sync+0x13/0x20
        [<ffffffffa0409f16>] ath10k_cancel_remain_on_channel+0x36/0x60 [ath10k_core]
        [<ffffffffa028c75c>] ieee80211_cancel_roc+0x1cc/0x2f0 [mac80211]
        [<ffffffffa028c8a2>] ieee80211_mgmt_tx_cancel_wait+0x22/0x30 [mac80211]
        [<ffffffffa0132288>] nl80211_tx_mgmt_cancel_wait+0xa8/0x130 [cfg80211]
        [<ffffffff816654a5>] genl_family_rcv_msg+0x1a5/0x3c0
        [<ffffffff81665749>] genl_rcv_msg+0x89/0xc0
        [<ffffffff81664e91>] netlink_rcv_skb+0xb1/0xc0
        [<ffffffff816650bc>] genl_rcv+0x2c/0x40
        [<ffffffff8166474d>] netlink_unicast+0x18d/0x200
        [<ffffffff81664add>] netlink_sendmsg+0x31d/0x430
        [<ffffffff8161a9ac>] sock_sendmsg+0x9c/0xd0
        [<ffffffff8161b469>] ___sys_sendmsg+0x389/0x3a0
        [<ffffffff8161bed9>] __sys_sendmsg+0x49/0x90
        [<ffffffff8161bf32>] SyS_sendmsg+0x12/0x20
        [<ffffffff8174c456>] system_call_fastpath+0x1a/0x1f

 -> #0 (&ar->conf_mutex){+.+.+.}:
        [<ffffffff810a0bde>] __lock_acquire+0x1b6e/0x1ce0
        [<ffffffff810a12e5>] lock_acquire+0x85/0x100
        [<ffffffff817491eb>] mutex_lock_nested+0x4b/0x370
        [<ffffffffa040a57d>] ath10k_scan_timeout_work+0x2d/0x50 [ath10k_core]
        [<ffffffff8106db41>] process_one_work+0x1b1/0x470
        [<ffffffff8106df63>] worker_thread+0x123/0x460
        [<ffffffff81073f34>] kthread+0xe4/0x100
        [<ffffffff8174c3ac>] ret_from_fork+0x7c/0xb0

 other info that might help us debug this:

  Possible unsafe locking scenario:

        CPU0                    CPU1
        ----                    ----
   lock((&(&ar->scan.timeout)->work));
                                lock(&ar->conf_mutex);
                                lock((&(&ar->scan.timeout)->work));
   lock(&ar->conf_mutex);

  *** DEADLOCK ***

Reported-by: Marek Puzyniak <marek.puzyniak@tieto.com>
Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
ath10k: change ce ring cleanup logic

Make ath10k_pci_init_pipes() effectively only
alter shared target-host data.

The per_transfer_context is a host-only thing.
It is necessary to preserve it's contents for a
more robust ring cleanup.

This is required for future warm reset fixes.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
ath10k: make warm reset a bit safer and faster

One of the problems with warm reset I've found is
that it must be guaranteed that copy engine
registers are not being accessed while being
reset. Otherwise in worst case scenario the host
may lock up.

Instead of using sleeps and hoping the device is
operational in some arbitrary timeframes use
firmware indication register.

As a side effect this makes driver
boot/stop/recovery faster.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
ath10k: split reset logic from power up

The power up procedure was overly complex due to
warm/cold reset workarounds and issues.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
ath10k: don't reset chip on power_down

Currently hif_power_up performs effectively a
reset and hif_stop resets the chip as well so
there's no point in resetting here.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
ath10k: fix possible bmi crash

While testing other things I've found that CE
items aren't cleared properly. This could lead to
null dereferences in BMI.

To prevent that make sure CE revoking clears the
nbytes value (which is used as a buffer completion
indication) and memset the entire CE ring data
shared between host and target when
(re)initializing.

Also make sure to check BMI xfer pointer and print
a splat instead of crashing the kernel.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
ath10k: expose hw restart via debugfs

Until now it was possible to simulate soft and
hard fw crashes but it wasn't possible to trigger
an immediately hw restart itself (without the fw
crash).

This can be useful when stress testing hw
restarting stability, e.g. during heavy tx/rx
traffic.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
ath10k: speed up hw recovery

In some cases hw recovery was taking an absurdly
long time due to ath10k waiting for things that
would never really complete.

Instead of waiting for inevitable timeouts poke
all completions and wakequeues and check if it's
still worth waiting.

Reading/writing ar->state requires conf_mutex.
Since waiters might be holding it introduce a new
flag CRASH_FLUSH so it's possible to tell waiters
to abort whatever they were waiting for.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>