staging: fbtft: Rectify GPIO handling

The infamous commit c440eee1a7a1 ("Staging: staging: fbtft: Switch to
the GPIO descriptor interface") broke GPIO handling completely.
It has already four commits to rectify and it seems not enough.
In order to fix the mess here we:

1) Set default to "inactive" for all requested pins

2) Fix CS#, RD#, and WR# pins polarity since it's active low
and GPIO descriptor interface takes it into consideration
from the Device Tree or ACPI

3) Consolidate chip activation (CS# assertion) under default
->reset() callback

To summarize the expectations about polarity for GPIOs:

RD# Low
WR# Low
CS# Low
RESET# Low
DC or RS High
RW High
Data 0 .. 15 High

See also Adafruit learning course [1] for the example of the schematics.

While at it, drop unneeded NULL checks, since GPIO API is tolerant to that.

[1]: https://learn.adafruit.com/adafruit-2-8-and-3-2-color-tft-touchscreen-breakout-v2/downloads

Fixes: 92e3e884887c ("Staging: fbtft: Fix GPIO handling")
Fixes: b918d1c27066 ("Staging: fbtft: Fix reset assertion when using gpio descriptor")
Fixes: dbc4f989c878 ("Staging: fbtft: Fix probing of gpio descriptor")
Fixes: c440eee1a7a1 ("Staging: fbtft: Switch to the gpio descriptor interface")
Cc: Jan Sebastian Götte <linux@jaseg.net>
Cc: Nishad Kamdar <nishadkamdar@gmail.com>
Reviewed-by: Phil Reid <preid@electromag.com.au>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20210503172114.27891-2-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Staging: fbtft: Switch to the gpio descriptor interface

This switches the fbtft driver to use GPIO descriptors
rather than numerical gpios:

Utilize the GPIO library's intrinsic handling of OF GPIOs
and polarity. If the line is flagged active low, gpiolib
will deal with this.

Remove gpios from platform device structure. Neither assign
statically numbers to gpios in platform device nor allow
gpios to be parsed as module parameters.

Signed-off-by: Nishad Kamdar <nishadkamdar@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

staging: fbtft: remove redundant license text

Now that the SPDX tag is in all fbtft files, that identifies the license
in a specific and legally-defined manner. So the extra GPL text wording
can be removed as it is no longer needed at all.

This is done on a quest to remove the 700+ different ways that files in
the kernel describe the GPL license text. And there's unneeded stuff
like the address (sometimes incorrect) for the FSF which is never
needed.

No copyright headers or other non-license-description text was removed.

Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

staging: fbtft: add SPDX identifiers

It's good to have SPDX identifiers in all files to make it easier to
audit the kernel tree for correct licenses.

Fix up the all of the staging fbtft drivers to have a proper SPDX
identifier, based on the license text in the file itself. The SPDX
identifier is a legally binding shorthand, which can be used instead of
the full boiler plate text.

This work is based on a script and data from Thomas Gleixner, Philippe
Ombredanne, and Kate Stewart.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

staging: fbtft: Fix alignment to match open parenthesis

Fix alignment issues by properly indenting function parameters in
accordance to the kernel coding style. Checkpatch pointed out this
issue.

CHECK: Alignment should match open parenthesis

Signed-off-by: Eva Rachel Retuya <eraretuya@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

staging: fbtft: Use standard MIPI DCS command defines for ili9340

This patch makes use of the standard MIPI Display Command Set to remove
some of the magic constants found in source code.

Signed-off-by: Priit Laes <plaes@plaes.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Staging: fbtft: Remove debug messages

Remove debug messages related to fbtft_par_dbg(DEBUG_INIT_DISPLAY.. )
as this info can be obtained using kernel function tracer

Signed-off-by: Shraddha Barke <shraddha.6596@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

staging/fbtft : Fix multiple/missing blank line issues

Remove or add blank lines as recommended by checkpatch.pl

Signed-off-by: Anish Bhatt <anish@chelsio.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

staging/fbtft : Remove repeated set_addr_win debug messages

fbtft_par_dbg(DEBUG_SET_ADDR_WIN.. ) is repeated in every
set_addr_win() handler, this could be replicated by using the kernel
function tracer instead.

Signed-off-by: Anish Bhatt <anish@chelsio.com>
Suggested-by: Greg KH <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

staging/fbtft : Remove FSF mailing address

checkpatch.pl recommends that this is no longer required.
Also replaces ASCII-art copyright notice with simple text

Signed-off-by: Anish Bhatt <anish@chelsio.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

staging: fbtft: Fix typo in fbtft

This patch fix spelling typo in comment and printk within fbtft

Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

staging: fbtft: fix space prohibited before that ','

This patch fixes the following checkpatch.pl error:
space prohibited before that ','

Signed-off-by: Aya Mahfouz <mahfouz.saif.elyazal@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

staging: fbtft: add fb_ili9340 driver

This commit adds the fb_ili9340 driver from the fbtft project at
https://github.com/notro/fbtft.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Noralf Tronnes <notro@tronnes.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>