There are a few errors at the PLL calculus, causing the device
to use wrong values.
While here, change the calculus to use 32 bits, as there's no
need for 64 bits there.
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>
Tested-by: NAntti Palosaari <crope@iki.fi>

r820t_standby() can be called before r820t_init().
If that happens, just do nothing.
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>
Tested-by: NAntti Palosaari <crope@iki.fi>

Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>
Tested-by: NAntti Palosaari <crope@iki.fi>

The rtl-sdr library disabled IMR callibration. While I'm not sure
yet why, it could be a good idea to add a modprobe parameter here,
to allow to also disable it. There are two rationale behind it:
- It helps to compare USB dumps between rtl-sdr and the Kernel module;
- If rtl-sdr disabled it, perhaps there's a good reason (e. g. it
  might not be actually working, or it might be causing some trouble).
For both cases, it seems useful to add a modprobe parameter to allow
testing the device with both configurations.
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>
Tested-by: NAntti Palosaari <crope@iki.fi>

Add the code to set the GPIO for this tuner. This code is
currently unused, so it is kept there only for completeness.
With this patch there are just two things that got left from
the original driver:
- At standby, there's another mode, not used by rtl2832u.
  Not sure if it might be needed in the future, but I suspect
  it is not used at all;
- There is a "fast tune" mode. As nor DVB or V4L API supports
  it, it seems an overkill to implement it.
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>
Tested-by: NAntti Palosaari <crope@iki.fi>

This code seems to calibrate I/Q phase and gain during the
device initialization.
This is done only once, and it doesn't seem to be needed to
happen after resuming.
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>
Tested-by: NAntti Palosaari <crope@iki.fi>

The rtl-sdr library, from where this driver was initially
based, doesn't use half PLL clock, but this is used on
the Realtek Kernel driver. So, also do the same here.
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>
Tested-by: NAntti Palosaari <crope@iki.fi>

Instead of using msleep(), use sleep_range(), as it provides
a closer sleep time.
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>
Tested-by: NAntti Palosaari <crope@iki.fi>

Just cosmetic changes: all other functions are prefixed
by r820t. Do the same for r820t_read().
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>
Tested-by: NAntti Palosaari <crope@iki.fi>

As we'll need to retrieve cached registers, make this
function explicit.
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>
Tested-by: NAntti Palosaari <crope@iki.fi>

If signal is zero, shows it as a zero, not as 0xff.
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>
Tested-by: NAntti Palosaari <crope@iki.fi>

This is part of the original driver, and adding it doesn't hurt,
so add it, to better sync the code.
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>
Tested-by: NAntti Palosaari <crope@iki.fi>

As the driver's logic uses the bit-reversed order for read,
use it as well when displaying the debug messages.
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>
Tested-by: NAntti Palosaari <crope@iki.fi>

The Realtek Kernel driver uses the second DVB-T 7MHz table instead
of the first one. Use it as well.
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>
Tested-by: NAntti Palosaari <crope@iki.fi>

On read, the bit order is inverted.
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>
Tested-by: NAntti Palosaari <crope@iki.fi>

IF is set at r820t_set_tv_standard(). So, we can't calculate
LO frequency before calling it.
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>
Tested-by: NAntti Palosaari <crope@iki.fi>

Scale used at get_if_freq and LO freq calculus is Hz.
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>
Tested-by: NAntti Palosaari <crope@iki.fi>

	[ 2255.342797] r820t 3-001a: generic_set_freq: PLL locked on frequency 725476191 Hz, gain=45
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>
Tested-by: NAntti Palosaari <crope@iki.fi>

As this tuner can be used by analog and digital parts of the
driver, be sure that all ops that access the hardware will
be be properly locked.
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>
Tested-by: NAntti Palosaari <crope@iki.fi>

This tuner works with 2 modes: automatic gain mode and manual
gain mode. Put it into automatic mode, as we currently don't
have any API for manual gain adjustment.
The logic to allow setting the manual mode is there, as it is
just a few extra code. This way, if/when we latter add support
for setting the gain mode, the code is already there.
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>
Tested-by: NAntti Palosaari <crope@iki.fi>

Instead of a binary signal strength measure, use the tuner gain
to obtain a better estimation of the signal strength.
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>
Tested-by: NAntti Palosaari <crope@iki.fi>

This driver was written from scratch, based on an existing driver
that it is part of rtl-sdr git tree, released under GPLv2:
	https://groups.google.com/forum/#!topic/ultra-cheap-sdr/Y3rBEOFtHug
	https://github.com/n1gp/gr-baz
	http://cgit.osmocom.org/rtl-sdr/plain/src/tuner_r820t.c
	(there are also other variants of it out there)
>From what I understood from the threads, the original driver was converted
to userspace from a Realtek tree. I couldn't find the original tree.
However, the original driver look awkward on my eyes. So, I decided to
write a new version from it from the scratch, while trying to reproduce
everything found there.
TODO:
- After locking, the original driver seems to have some routines to
  improve reception. This was not implemented here yet.
- RF Gain set/get is not implemented.
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>
Tested-by: NAntti Palosaari <crope@iki.fi>