NFC: trf7970a: disable all regulators on removal

During module probe, regulator 'vin' and 'vdd-io' are used and enabled,
but the vdd-io regulator overwrites the 'vin' regulator pointer. During
remove, only the vdd-io is disabled, as the vin regulator pointer is not
available anymore. When regulator_put() is called during resource
cleanup a kernel warning is given, as the regulator is still enabled.

Store the two regulators in separate pointers and disable both the
regulators on module remove.

Fixes: 49d22c70aaf0 ("NFC: trf7970a: Add device tree option of 1.8 Volt IO voltage")
Signed-off-by: Paul Geurts <paul_geurts@live.nl>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/DB7PR09MB26847A4EBF88D9EDFEB1DA0F950E2@DB7PR09MB2684.eurprd09.prod.outlook.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

nfc: trf7970a: mark OF related data as maybe unused

The driver can be compile tested with !CONFIG_OF making certain data
unused:

drivers/nfc/trf7970a.c:2232:34: error: ‘trf7970a_of_match’ defined but not used [-Werror=unused-const-variable=]

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Reviewed-by: Mark Greer <mgreer@animalcreek.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

spi: make remove callback a void function

The value returned by an spi driver's remove function is mostly ignored.
(Only an error message is printed if the value is non-zero that the
error is ignored.)

So change the prototype of the remove function to return no value. This
way driver authors are not tempted to assume that passing an error to
the upper layer is a good idea. All drivers are adapted accordingly.
There is no intended change of behaviour, all callbacks were prepared to
return 0 before.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Marc Kleine-Budde <mkl@pengutronix.de>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Acked-by: Miquel Raynal <miquel.raynal@bootlin.com>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Acked-by: Claudius Heine <ch@denx.de>
Acked-by: Stefan Schmidt <stefan@datenfreihafen.org>
Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Acked-by: Ulf Hansson <ulf.hansson@linaro.org> # For MMC
Acked-by: Marcus Folkesson <marcus.folkesson@gmail.com>
Acked-by: Łukasz Stelmach <l.stelmach@samsung.com>
Acked-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20220123175201.34839-6-u.kleine-koenig@pengutronix.de
Signed-off-by: Mark Brown <broonie@kernel.org>

nfc: trf7970a: drop unneeded debug prints

ftrace is a preferred and standard way to debug entering and exiting
functions so drop useless debug prints.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Acked-by: Mark Greer <mgreer@animalcreek.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

nfc: trf7970a: constify several pointers

Several functions do not modify pointed data so arguments and local
variables can be const for correctness and safety.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

nfc: constify nfc_digital_ops

Neither the core nor the drivers modify the passed pointer to struct
nfc_digital_ops, so make it a pointer to const for correctness and safety.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

nfc: fix typo

change 'regster' to 'register'

Signed-off-by: wengjianfeng <wengjianfeng@yulong.com>
Acked-by: Mark Greer <mgreer@animalcreek.com>
Link: https://lore.kernel.org/r/20210123082550.3748-1-samirweng1979@163.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

nfc: remove unneeded break

A break is not needed if it is preceded by a return

Signed-off-by: Tom Rix <trix@redhat.com>
Link: https://lore.kernel.org/r/20201019191500.9264-1-trix@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

treewide: Use fallthrough pseudo-keyword

Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

[1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 417

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 of
the license as published by the free software foundation

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-only

has been chosen to replace the boilerplate/reference in 1 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Armijn Hemel <armijn@tjaldur.nl>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190531190113.328655274@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

NFC: trf7970a: Correct register settings for 27MHz clock

In prior commits the selected clock frequency does not propagate
correctly to what is written to the TRF7970A_MODULATOR_SYS_CLK_CTRL
register.

Signed-off-by: Geoff Lansberry <geoff@kuvee.com>
Acked-by: Mark Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

Revert "NFC: trf7970a: Handle extra byte in response to Type 5 RMB commands"

This reverts commit ab714817d7e891608d31f6996b1e4c43cf2bf342.

The original commit was designed to handle a bug in the trf7970a NFC
controller where an extra byte was returned in Read Multiple Blocks (RMB)
command responses. However, it has become less clear whether it is a bug
in the trf7970a or in the tag. In addition, it was assumed that the extra
byte was always returned but it turns out that is not always the case. The
result is that a byte of good data is trimmed off when the extra byte is
not present ultimately causing the neard deamon to fail the read.

Since the trf7970a driver does not have the context to know when to trim
the byte or not, remove the code from the trf7970a driver all together
(and move it up to the neard daemon). This has the added benefit of
simplifying the kernel driver and putting the extra complexity into
userspace.

CC: Rob Herring <robh@kernel.org>
CC: devicetree@vger.kernel.org
Signed-off-by: Mark Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: fix check of clock frequencies, use && instead of ||

The "or" condition (clk_freq != TRF7970A_27MHZ_CLOCK_FREQUENCY) ||
(clk_freq != TRF7970A_13MHZ_CLOCK_FREQUE) will always be true because
clk_freq cannot be equal to two different values at the same time. Use
the && operator instead of || to fix this.

Detected by CoverityScan, CID#1430468 ("Constant expression result")

Fixes: 837eb4d21ecde7 ("NFC: trf7970a: add device tree option for 27MHz clock")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Geoff Lansberry <geoff@kuvee.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: Clean up coding style issues

Clean up coding style issues according to scripts/Lindent.
Some scripts/Lindent changes were reverted when it appeared
to make the code less readable or when it made the line run
over 80 characters.

Signed-off-by: Mark Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: Convert to descriptor based GPIO interface

The trf7970a driver uses the deprecated integer-based GPIO consumer
interface so convert it to use the new descriptor-based GPIO
consumer interface.

Signed-off-by: Mark Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: Remove support for 'vin-voltage-override' DT property

The 'vin-voltage-override' DT property is used by the trf7970a
driver to override the voltage presented to the driver by the
regulator subsystem. This is unnecessary as properly specifying
the regulator chain via DT properties will accomplish the same
thing. Therefore, remove support for 'vin-voltage-override'.

Signed-off-by: Mark Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: Remove useless comment

The last entry in the trf7970a_of_match[] table must be an empty
entry to demarcate the end of the table. Currently, there is a
comment indicating this but it is obvious so remove the comment.

Signed-off-by: Mark Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: Only check 'en2-rf-quirk' if EN2 is specified

The quirk indicated by the 'en2-rf-quirk' device tree property
is only relevant when there is a GPIO connected to the EN2 pin
of the trf7970a. This means we should only check for 'en2-rf-quirk'
when EN2 is specified in the 'ti,enable-gpios' property of the
device tree.

Signed-off-by: Mark Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: Fix inaccurate comment in trf7970a_probe()

As of commit ce69b95ca4e4 ("NFC: Make EN2 pin optional in the
TRF7970A driver"), only the GPIO for the 'EN' enable pin needs
to be specified in the device tree so update the comments that
says both 'EN' and 'EN2' must be specified.

Signed-off-by: Mark Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: Don't de-assert EN2 unless it was asserted

When the trf7970a part has the bug related to 'en2-rf-quirk',
the GPIO connected to the EN2 pin will not be asserted by the
driver when powering up so it shouldn't be de-asserted when
powering down.

Signed-off-by: Mark Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: Add device tree option of 1.8 Volt IO voltage

The TRF7970A has configuration options for supporting hardware designs
with 1.8 Volt or 3.3 Volt IO. This commit adds a device tree option,
using a fixed regulator binding, for setting the io voltage to match
the hardware configuration. If no option is supplied it defaults to
3.3 volt configuration.

Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Mark Greer <mgreer@animalcreek.com>
Signed-off-by: Geoff Lansberry <geoff@kuvee.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: add device tree option for 27MHz clock

The TRF7970A has configuration options to support hardware designs
which use a 27.12MHz clock. This commit adds a device tree option
'clock-frequency' to support configuring the this chip for default
13.56MHz clock or the optional 27.12MHz clock.

Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Mark Greer <mgreer@animalcreek.com>
Signed-off-by: Geoff Lansberry <geoff@kuvee.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: Make EN2 pin optional in the TRF7970A driver

Make the EN2 pin optional. This is useful for boards,
which have this pin fix wired, for example to ground.

Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Guan Ben <ben.guan@cn.bosch.com>
Signed-off-by: Mark Jonas <mark.jonas@de.bosch.com>
Signed-off-by: Heiko Schocher <hs@denx.de>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: add TI recommended write of zero to Register 0x18

Signed-off-by: Geoff Lansberry <geoff@kuvee.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: use to_spi_device

Use to_spi_device() instead of open-coding it.

Signed-off-by: Geliang Tang <geliangtang@163.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

spi: Drop owner assignment from spi_drivers

An spi_driver does not need to set an owner, it will be populated by the
driver core.

Signed-off-by: Andrew F. Davis <afd@ti.com>
Acked-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

NFC: trf7970a: Add OF match table

The Documentation/devicetree/bindings/net/nfc/trf7970a.txt DT binding doc
lists "ti,trf7970a" as a compatible string but the corresponding driver
does not have an OF match table. Add the table to the driver so the SPI
core can do an OF style match.

Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: Add NULL check to clear up smatch warning

Although it should be unnecessary, add a NULL pointer check
to trf7970a_send_upstream() to eliminate a smatch warning.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Mark Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: SDD_EN is bit 5 not bit 3

The SDD_EN bit in the NFC Target Detection Level Register
is bit 5 not bit 3 so change the TRF7970A_NFC_TARGET_LEVEL_SDD_EN
macro accordingly.

Reported-by: Raymond Lei <Raymond.Lei@ecolab.com>
Signed-off-by: Mark Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: Handle extra byte in response to Type 5 RMB commands

The current versions of the trf7970a has an erratum where it returns
an extra byte in the response to 'Read Multiple Block' (RMB) commands.
This command is issued to Type 5 tags (i.e., ISO/IEC 15693 tags) by
the neard daemon.

To handle this, define a new Device Tree property,
't5t-rmb-extra-byte-quirk', which indicates that the associated
trf7970a device has this erratum. The trf7970a device driver
will then ensure that the response length to RMB commands is
reduced by one byte (for devices with the erratum).

Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC / PM: Replace CONFIG_PM_RUNTIME with CONFIG_PM

After commit b2b49ccbdd54 (PM: Kconfig: Set PM_RUNTIME if PM_SLEEP is
selected) PM_RUNTIME is always set if PM is set, so #ifdef blocks
depending on CONFIG_PM_RUNTIME may now be changed to depend on
CONFIG_PM.

Replace CONFIG_PM_RUNTIME with CONFIG_PM in drivers/nfc/trf7970a.c.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

NFC: trf7970a: Unlock mutex before exiting _trf7970a_tg_listen()

The recently added _trf7970a_tg_listen() routine
has some return paths that don't unlock the mutex
that is locked when the routine is entered. Fix
this by always unlocking the mutex before returning.

Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: Unlock mutex before exiting trf7970a_irq()

Recent changes to trf7970a_irq() added a couple return
paths that don't unlock the mutex that is locked when
the routine is entered. Fix this by ensuring the mutex
is always unlocked before returning.

Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: Remove unnecessary local variable initialization

There is no need to initialize the 'ret' variable
in trf7970a_resume().

Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: Remove useless local variable

The trf7970a_suspend() routine always returns
zero so don't use a local return variable to
hold the return value. This fixes up a smatch
warning.

Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: Add Target Mode Detection Support

Add the ability to detect the mode (i.e., RF technology)
used by the initiator. The RF technology that was
detected can be retrieved by calling the 'tg_get_rf_tech'
driver hook.

Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: Add Target Mode Support

Add target mode support to the trf7970a
NFC driver. This effectively enables full
Peer-to-Peer support.

To handle changing framing between sending
a response frame and receiving the subsequent
request frame, most of the framing changes
take effect in the interrupt handler and not
in trf7970a_tg_config_framing().

Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: Handle timeout values of zero

The digital layer can try to send a command with a
timeout value of zero (e.g., digital_tg_send_psl_res().
The zero value is used as a flag to indicate that
the driver should not expect a response. To handle
this, the driver sets an internal timer because it
should still get an interrupt with the TX bit set
in the IRQ Status Register. When it gets that
interrupt, it returns a return value of '0'.
If it doesn't get the interrupt before timing out,
it returns ETIMEDOUT as usual.

Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: Cancel timer when error encountered

Some paths leave a timer still running when
trf7970a_send_err_upstream() is called. This
can cause a timeout to occur in a subsequent
transaction making it fail. Fix this by ensuring
there is no timer running before sending an error
upstream.

Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: Don't turn on RF if there is already an RF field

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>

NFC: trf7970a: trf7970a_init() turns off the RF transmitter

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>

NFC: trf7970a: Don't turn off RF if its already off

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>

NFC: trf7970a: Add '_in_' to initiator routines

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>

NFC: trf7970a: Delay after initialization

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>

NFC: trf7970a: Add System Suspend/Resume support

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>

NFC: trf7970a: Create startup and shutdown routines

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>

NFC: trf7970a: Don't assume CONFIG_PM_RUNTIME is enabled

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>

NFC: trf7970a: Rename TRF7970A_ST_OFF to TRF7970A_ST_RF_OFF

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>

NFC: trf7970a: Return error code when turning on RF fails

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>

NFC: trf7970a: Ensure no more RX data before completing receive

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>

NFC: trf7970a: Reread FIFO Status Register when draining FIFO

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>

NFC: trf7970a: Handle low-watermark IRQ when transmitting

Commit 4dd836e46c3d ("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>

NFC: trf7970a: Only fill FIFO if there is space

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>

NFC: trf7970a: Prefix TX data when refilling FIFO

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>

NFC: trf7970a: Remove unnecessary FIFO reset & RSSI read

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>

NFC: trf7970a: Clear possible spurious interrupt before transmitting

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>

NFC: trf7970a: Recalculate driver timeout values

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>

NFC: trf7970a: Add RF technology specific guard times

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>

NFC: trf7970a: Initialize when enabling RF

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>

NFC: trf7970a: Disable SYS_CLK Output

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>

NFC: trf7970a: Remove unnecessary sleep

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>

NFC: trf7970a: FIFO Size is really 127 bytes

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>

NFC: trf7970a: Ignore Overflow bit in FIFO Status Register

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>

NFC: trf7970a: Use spi_sync() instead of spi_write_then_read()

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>

NFC: trf7970a: Call spi_setup() to configure SPI communication

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>

NFC: trf7970a: Remove trf7970a_tg_listen_mdaa()

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>

NFC: trf7970a: Remove incorrect of_node_put() call

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>

NFC: trf7970a: Make gpio labels more readable

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>

NFC: trf7970a: Add quirk to keep EN2 low

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>

NFC: trf7970a: Move IRQ Status Read quirk to device tree

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>

NFC: trf7970a: Add VIN voltage override support

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>

NFC: trf7970a: Add support for Felica Type 3 tags

Add support for the Felica protocol and Type 3 tags.
Both 212 and 424 kbps are supported.

Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: Add support for the ISO/IEC 14443-B and Type 4B tags

Now that the NFC digital layer has support for the ISO/IEC 14443-B
protocol and type 4B tags, add the corresponding support to the
trf7970a driver.

Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: Add 'autosuspend-delay' DTS property

The trf7970a driver currently uses a fixed autosuspend delay of 30 seconds.
To enable users to customize the delay as they see fit, add support for the
new 'autosuspend-delay' DTS property (part of the nfc node) which can
override the default 30 seconds.

Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: Don't return value from trf7970a_switch_rf_on()

trf7970a_switch_rf_on() no longer returns anything other than 0 so make
it void and clean up the code that checks for errors when its called.

Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: Add pm_runtime support

Add pm_runtime support by moving the code that enables the trf7970a to
the pm_runtime hook routines. The pm_runtime 'autosuspend' feature is
used so that the device isn't disabled until at least 30 seconds have
passed since trf7970a_switch_rf_off() was last called.

The result is that when trf7970a_switch_rf_on() is called, the device
will be enabled and initialized (if it isn't already). When
trf7970a_switch_rf_off() is called, it will turn off the RF immediately
but leave the device enabled for at least 30 seconds.
If 30 seconds have passed and the pm_runtime facility decides to suspend
the driver, the device will be disabled then.

Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: Turn RF on after hardware is configured

The NFC digital layer calls the 'switch_rf' hook to turn the RF on before
it configures the RF technology and framing. There is potential to confuse
a tag doing it this way so don't enable the RF until the RF technology and
initial framing have been configured.

Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: Set correct Vin voltage in Chip Status Control register

Currently, the trf7970a driver assumes that the Vin voltage is 5V when
it writes to the 'Chip Status Control' register. That may not be correct
so use the regulator facility to get the Vin voltage and set the VRS5_3
bit correctly when writing to that register.

Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: Allow different Modulator and SYS_CLK Control register values

Currently the driver writes the same value to the 'Modulator and SYS_CLK
Control' register no matter what RF technology is being used. That works
for now but new RF technologies (e.g., ISO/IEC 14443-B) will require
different values to be written to that register. To support this, add a
member to the trf7970a structure which is set by the RF technology handling
code and used by the framing code when it writes to that register.

Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: Set 'Modulator and SYS_CLK Control' after 'ISO Control'

Writing to the 'ISO Control' register may cause the contents of the
'Modulator and SYS_CLK Control' register to change so be sure to write
to 'Modulator and SYS_CLK Control' after writing to 'ISO Control'.

Note that writing to the 'Modulator and SYS_CLK Control' register
shouldn't be necessary at all according to the trf790a manual but testing
shows that it is necessary.

Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: Only write 'ISO Control' when its changing

The current code always writes to the 'ISO Control' register when the
RF framing is set. That's not necessary since the register's value
doesn't always change. Instead, only write to it when its value is
actually being changed.

Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: Reset FIFO when 'End of TX' Interrupt Occurs

Sometimes after sending a frame there is tx data leftover in the FIFO
which the driver will think is part of the receive frame. That data can
be cleared when an 'End of TX' interrupt is received by issuing the
'FIFO Reset' command.

Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: Clear 'NFC Target Detection Level' register

Due to a trf7970a erratum, the 'NFC Target Detection Level' register
(0x18) must be cleared after power-up.

Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: Only abort a command if one is active

Only initiate the abort command process when there is an active command.
If the abort process were started and there wasn't an active command
then the next command issued by the digital layer would be incorrectly
aborted.

Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: Increase TRF7970A_WAIT_FOR_RX_DATA_TIMEOUT to 20 ms

After further testing periods of ~16 ms have been observed
between interrupts indicating that there is receive data in
the FIFO. To accomodate that, increase the time the driver
waits before deciding there is no more data to receive to
20 ms. The macro that represents that delay is
'TRF7970A_WAIT_FOR_RX_DATA_TIMEOUT'.

Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: Add ISO/IEC 15693 and Type 5 tag Support

Add support for ISO/IEC 15693 RF technology and Type 5 tags.
Note that Type 5 tags used to be referred to as Type V tags.

CC: Erick Macias <emacias@ti.com>
CC: Felipe Balbi <balbi@ti.com>
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: Add support for Type 4A Tags

Add support for Type 4A Tags which includes
supporting the underlying ISO/IEC 14443-A
protocol.

Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: trf7970a: Add driver with ISO/IEC 14443 Type 2 Tag Support

Add a driver for the Texas Instruments TRF7970a RFID/NFC/15693
transceiver. The driver currently supports ISO/IEC 14443 Type 2
tags only (MIFARE Ultralight and Ultralight C but not Classic).

CC: Erick Macias <emacias@ti.com>
CC: Felipe Balbi <balbi@ti.com>
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>