staging/atomisp: Add support for the Intel IPU v2

This patch adds support for the Intel IPU v2 as found on Android and IoT
Baytrail-T and Baytrail-CR platforms (those with the IPU PCI mapped). You
will also need the firmware files from your device (Android usually puts
them into /etc) - or you can find them in the downloadable restore/upgrade
kits if you blew them away for some reason.

It may be possible to extend the driver to handle the BYT/T windows
platforms such as the ASUS T100TA. These platforms don't expose the IPU via
the PCI interface but via ACPI buried in the GPU description and with the
camera information somewhere unknown so would need a platform driver
interface adding to the codebase *IFF* the firmware works on such devices.

To get good results you also need a suitable support library such as
libxcam. The camera is intended to be driven from Android so it has a lot of
features that many desktop apps don't fully spport.

In theory all the pieces are there to build it with -DISP2401 and some
differing files to get CherryTrail/T support, but unifying the drivers
properlly is a work in progress.

The IPU driver represents the work of a lot of people within Intel over many
years. It's historical goal was portability rather than Linux upstream. Any
queries about the upstream aimed driver should be sent to me not to the
original authors.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 64 insertions, 0 deletions

diff --git a/drivers/staging/media/atomisp/TODO b/drivers/staging/media/atomisp/TODO
new file mode 100644
index 000000000000..737452cbf8a0
--- /dev/null
+++ b/drivers/staging/media/atomisp/TODO
@@ -0,0 +1,64 @@
+1. A single AtomISP driver needs to be implemented to support both BYT and
+   CHT platforms. The current driver is a mechanical and hand combined merge
+   of the two using an ifdef ISP2401 to select the CHT version, which at the
+   moment is not enabled. Eventually this should become a runtime if check,
+   but there are some quite tricky things that need sorting out before that
+   will be possible.
+
+2. The file structure needs to get tidied up to resemble a normal Linux
+   driver.
+
+3. Lots of the midlayer glue. unused code and abstraction needs removing.
+
+3. The sensor drivers read MIPI settings from EFI variables or default to the
+   settings hard-coded in the platform data file for different platforms.
+   This isn't ideal but may be hard to improve as this is how existing
+   platforms work.
+
+4. The sensor drivers use the regulator framework API. In the ideal world it
+   would be using ACPI but that's not how the existing devices work.
+
+5. The AtomISP driver includes some special IOCTLS (ATOMISP_IOC_XXXX_XXXX)
+   that may need some cleaning up.
+
+6. Correct Coding Style. Please don't send coding style patches for this
+   driver until the other work is done.
+
+7. The ISP code depends on the exact FW version. The version defined in
+   BYT: 
+   drivers/staging/media/atomisp/pci/atomisp2/css2400/sh_css_firmware.c
+   static const char *release_version = STR(irci_stable_candrpv_0415_20150521_0458);
+   CHT:
+   drivers/staging/media/atomisp/pci/atomisp2/css/sh_css_firmware.c
+   static const char *release_version = STR(irci_ecr-master_20150911_0724);
+
+   At some point we may need to round up a few driver versions and see if
+   there are any specific things that can be done to fold in support for
+   multiple firmware versions.
+
+
+Limitations:
+
+1. Currently the patch only support some camera sensors
+   gc2235/gc0310/0v2680/ov2722/ov5693/mt9m114...
+
+2. To test the patches, you also need the ISP firmware
+
+   for BYT:/lib/firmware/shisp_2400b0_v21.bin
+   for CHT:/lib/firmware/shisp_2401a0_v21.bin
+
+   The firmware files will usually be found in /etc/firmware on an Android
+   device but can also be extracted from the upgrade kit if you've managed
+   to lose them somehow.
+
+3. Without a 3A libary the capture behaviour is not very good. To take a good
+   picture, you need tune ISP parameters by IOCTL functions or use a 3A libary
+   such as libxcam.
+
+4. The driver is intended to drive the PCI exposed versions of the device.
+   It will not detect those devices enumerated via ACPI as a field of the
+   i915 GPU driver.
+
+5. The driver supports only v2 of the IPU/Camera. It will not work with the
+   versions of the hardware in other SoCs.
+