Currently, the trf7970a driver blindly turns on its
RF field when configuring its framing.  This isn't
a good idea if there is already a device generating
an RF field.  Instead, check if there is already an
RF field present before turning on this device's RF
field and, if there is, return EBUSY.
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

When trf7970a_init() initializes the trf7970a it
implicitly turns off the RF transmitter.  Track
this by clearing the TRF7970A_CHIP_STATUS_RF_ON
bit in the cached trf->chip_status_ctrl.
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

Don't try to turn off of RF transmitter is its
already off.
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

Rename trf7970a_config_rf_tech() and trf7970a_config_framing()
to trf7970a_in_config_rf_tech() and trf7970a_in_config_framing(),
respectively to avoid confusion when target support is added.
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

The trf7970a should be given at least 1 ms to
completely initialize after the 'Software Init'
and 'Idle' commands have been issued.
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

Add system suspend/resume support by gracefully
shutting things down when suspending and bringing
the device back to full power when resuming.
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

Encapsulate the code to start up and gracefully
shutdown the driver and trf7970a device.  Doing
this makes adding system suspend/resume support
easier and the resulting code cleaner.
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

The current code assumes that CONFIG_PM_RUNTIME
is always defined so it won't power up the trf7970a
when it isn't enabled.  Fix this by moving the power
up/down code from the pm_runtime_resume/suspend
routines into their own routines and calling the
power up function from the probe routine.  This
ensures the device is powered up even when
CONFIG_PM_RUNTIME is not defined.

In order to not power on/off a device that is
already powered on/off, create a new state to
indicate that the power is off (TRF7970A_ST_PWR_OFF).
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

Rename the 'TRF7970A_ST_OFF' state to 'TRF7970A_ST_RF_OFF'
to make it clear that this state means that the RF is
off and not the entire device.
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

trf7970a_switch_rf_on() is currently a void function
but turning on the RF could fail so it should return
a return code.  That return code should also be
propagated back to the entity that initiated the
action.
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

Depending on the interrupt status value given by the
trf7970a, the driver may not know when a receive operation
is complete.  To handle this, the driver waits for a period
of time in case the trf7970a interrupts it again indicating
there are more RX data in the FIFO.  It is possible that the
timeout will occur when there are RX data in the FIFO but
before the trf7970a has generated an interrupt to tell the
driver about it.  Handle this by calling trf7970a_drain_fifo()
(instead of trf7970a_send_upstream() which just passes up the
data gathered to far) to check if there are more data in the
FIFO.  If so, gather that data into the receive buffer.  If
not, pass the data collected so far upstream as before.
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

Receiving an interrupt whose Interrupt Status Register
value has only the SRX bit set is supposed to mean that
all of the data from the tag has been received.  That
turns out to not be true so we need to reread the FIFO
Status Register to tell if there are any new bytes in
the FIFO.  If there are, continue receiving them; if
there aren't, assume that the receive is complete and
pass the data up.
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

Commit 4dd836e4 ("NFC: trf7970a: Reset FIFO when
'End of TX' Interrupt Occurs") fixes the issue that
it was meant to fix but adds the unfortunate side
effect of causing the driver to report an error
when the TX low-watermark level is passed during
transmits.  This can be fixed by checking whether
the IRQ status indicates that the low-watermark
has been passed when transmitting.  If it has been
passed and the FIFO is empty, then its safe to reset
the FIFO.  Otherwise, silently continue since another
TX interrupt will be generated and the FIFO will be
reset then.
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

Handle the case where trf7970a_fill_fifo() is
called but there is no room in the FIFO for
more TX data.  When this happens, wait for
another interrupt indicating that there is
now space (and set a timer in case that
interrupt never occurs).
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

When refilling the FIFO with more TX data (using a new
SPI transaction), the driver must prefix the TX data with
a write to the FIFO I/O Register.  This tells the trf7970a
that the following data is destined for the FIFO so it can
be transmitted.

To accomplish this, the driver cannot simply push the
prefix data just before the next set of TX data that
is to be transmitted because that will overwrite part
of the TX data provided by the digital layer.  Instead,
separate the prefix data and the TX data when calling
trf7970a_transmit().  trf7970a_transmit() can then send
the prefix and TX data from different memory locations
with one spi_sync() operation.  This also means that
the driver doesn't require any skb "tx_headroom" as
provided by the digital layer (see
nfc_digital_allocate_device() and digital_skb_alloc()).

Also ensure that the prefix is of type 'u8' and not
'char'.
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

It is no longer necessary to reset the FIFO and
read the 'RSSI Levels and Oscillator Status Register'
so remove that code.
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

The trf7970a occasionally generates spurious interrupts
which can confuse the driver.  To help alleviate this,
clear any interrupts by reading the 'IRQ Status Register'
before starting a new transaction.
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

Some of the timeout values used in the driver
are not long enough to handle worst-case scenarios
so they need to be recalculated.

The time to wait for the FIFO to drain past the
low-watermark is now 20 ms because it can take
around 14.35 ms to send 95 bytes (127 bytes in
full FIFO minus 32 bytes where the low-watermark
interrupt will fire).  95 bytes will take around
14.35 ms at 6.62 kbps (the lowest supported bit
rate used by ISO/IEC 15693) so 20 ms should be a
safe value.

The time to wait before issuing an EOF to complete
an ISO/IEC 15693 write or lock command is 40 ms--
20 ms to drain the FIFO and another 20 ms to ensure
the wait is long enough before sending an EOF.
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

When turning on the RF field, the driver must wait
an RF-technology-specific amount of time (known as
the guard time) before modulating the field.
Currently, the driver waits 5 ms but that is too
short for NFCF and too long for ISO/IEC 15693.
Fix this by determining the guard time when the
RF technology is set and delaying that amount
of time when turning on the RF field.
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

Currently, the trf7970a is reset & initialized only
when the pm_runtime resume hook is called.  Instead,
initialize it every time the RF is enabled to ensure
that the trf7970a is quiesced and in a known state
before being set up for another RF technology.
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

Currently, support for providing the external
SYS_CLK signal on pin 27 is not supported so
turn it off by writing to the 'Modulator and
SYS_CLK Control' register immediately after
reset.
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

There is no need to sleep for 1-2 ms before
transmitting a new command.
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

Despite what the manual says, the FIFO size
on the trf7970a is really 127 bytes so make
the code respect that.
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

The Overflow bit in the 'FIFO Status Register' has
proven to be untrustworthy so ignore it.
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

To more efficiently handle long continuous reads,
use spi_sync() instead of spi_write_then_read().
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

Call spi_setup() to configure SPI communication
with the trf7970a.  This will ensure that the
correct SPI parameters are used.
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

Currently, the digital layer 'tg_listen_mdaa'
hook is not used and it isn't necessary to have
a stub routine so remove it.
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

of_property_read_u32() does not take a reference
to the specified OF node so don't call of_node_put()
in trf7970a_get_autosuspend_delay().
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NCI RF FRAME interface is used for all kind of tags
except ISODEP ones. So for all other kind of tags the
status byte has to be removed.
Signed-off-by: Vincent Cuissard <cuissard@marvell.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

All contexts have to be initiliazed before calling
nfc_register_device otherwise it is possible to call
nci_dev_up before ending the nci_register_device
function. In such case kernel will crash on non
initialized variables.
Signed-off-by: Vincent Cuissard <cuissard@marvell.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

Update nci.h to respect latest NCI specification proposal
(stop using proprietary opcodes). Handle ISO15693 parameters
in NCI_RF_ACTIVATED_NTF handler.
Signed-off-by: Vincent Cuissard <cuissard@marvell.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

Make the labels for the two gpio enable lines
more user friendly by prefixing them with the
driver name.
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

Current versions of the trf7970a have an erratum where
the EN2 pin must be kept low.  If it isn't kept low,
it will generate an RF field even when in passive
target mode.  To work around this issue, create the
'en2-rf-quirk' device tree property to indicate that
the trf7970a that the driver is using has this erratum.
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

A bug has been discovered in the trf7970a where it
will generate an RF field even in passive target
mode when EN2 is asserted.  To work around this,
add support for the 'en2-rf-quirk' device tree
property which indicates that EN2 must remain low.
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

The mechanism for specifying that the trf7970a
being used by the driver has the "IRQ Status Read"
erratum has been changed to a device tree property
('irq-status-read-quirk').

Document the new device tree property.
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

The quirk indicating whether the trf7970a has
the "IRQ Status Read" erratum or not is currently
implemented using the 'driver_data' member of the
'spi_device_id' structure.  That requires the
driver to be modified to turn the quirk off when
a version of the trf7970a that doesn't have the
erratum is being used.  To fix that, create a
new device tree property called
'irq-status-read-quirk' that indicates that the
trf7970a being used has the erratum.

While at it, rename 'TRF7970A_QUIRK_IRQ_STATUS_READ_ERRATA'
to 'TRF7970A_QUIRK_IRQ_STATUS_READ' to make it
less of an eyesore.
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

The trf7970a driver recently had support for the
'vin-voltage-override' property added to it.  This
property is used to override the value given by
the regulator subsystem for the VIN pin's voltage.
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

The trf7970a driver uses the voltage from the
power/regulator subsystem to determine what the
voltage on the VIN pin is.  Normally, this is
the right thing to do but sometimes the board
that the trf7970a is on may change the voltage.
This is the case for the trf7970atb board from
Texas Instruments where it boosts the VIN voltage
from 3.3V to 5V (see http://www.ti.com/tool/trf7970atb).

To handle this, add support for the 'vin-voltage-override'
device tree property which overrides the voltage value
given by the regulator subsystem.  When the DT property
is not present, the value from the regulator subsystem
is used.

The value of 'vin-voltage-override' is in uVolts.
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

In order to operate at the fasted bit rate
possible, add initiator-side support for
PSL REQ while in P2P mode.  The PSL REQ
will switch the RF technology to 424F
whenever possible.
Reviewed-by: Thierry Escande <thierry.escande@linux.intel.com>
Tested-by: Thierry Escande <thierry.escande@linux.intel.com>
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

According to RCU_INIT_POINTER()'s block comment 3.a, it can be used if
"3.   The referenced data structure has already been exposed to readers either
at compile time or via rcu_assign_pointer() -and-
 a.   You have not made -any- reader-visible changes to this structure since
then".

This case fulfills the conditions above because between the rcu_dereference()
call (cvif = rcu_dereference(ar->beacon_iter);) and the rcu_assign_pointer()
call there is no update of the "cvif" variable.
Therefore, this patch makes the replacement.

The following Coccinelle semantic patch was used:
@@
identifier v;
@@

v = rcu_dereference(...);
... when != rcu_dereference(...);
    when != v = ...;
    when != (<+...v...+>)++;
    when != \(memcpy\|memset\)(...);
(
- rcu_assign_pointer
+ RCU_INIT_POINTER
  (..., v);
|
 if(...) {
... when != v = ...;
- rcu_assign_pointer
+ RCU_INIT_POINTER
  (..., v);
... when any
 }
)

Because there are cases where between a “rcu_dereference()” call and a
“rcu_assign_pointer()” call might be updates of the value that interests us,
the Coccinelle semantic patch ignores them and replaces with
"RCU_INIT_POINTER()" only when the update is not happening.
Signed-off-by: Andreea-Cristina Bernat <bernat.ada@gmail.com>
Acked-by: Christian Lamparter <chunkeey@googlemail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>