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

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

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

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

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

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

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

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

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

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

Due to a trf7970a erratum, the 'NFC Target Detection Level' register
(0x18) must be cleared after power-up.
Signed-off-by: NMark A. Greer <mgreer@animalcreek.com>
Signed-off-by: NSamuel Ortiz <sameo@linux.intel.com>

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

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

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

Add support for Type 4A Tags which includes
supporting the underlying ISO/IEC 14443-A
protocol.
Signed-off-by: NMark A. Greer <mgreer@animalcreek.com>
Signed-off-by: NSamuel Ortiz <sameo@linux.intel.com>

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