The patchset will add a driver to support basic functionality for
XRA1403 device. Features supported:
        - get/set GPIO direction (input, output)
        - get/set GPIO level (low, high)

Documentation: A gpio-xra1403.txt file was added to document the DTS
	bindings related to driver.

Testing:

1.1 XRA1403 connected to iMX53 MCU
1.2 Use the GPIO tools provided by kernel from tools/gpio dir

2.1 `lsgpio`

root@csmon ppd:~# lsgpio
GPIO chip: gpiochip8, "xra1403", 16 GPIO lines
        line  0: unnamed unused [output]
        line  1: unnamed unused [output]
        line  2: unnamed unused [output]
        line  3: unnamed unused [output]
        line  4: unnamed unused [output]
        line  5: unnamed unused
        line  6: unnamed unused
        line  7: unnamed unused [output]
        line  8: unnamed unused [output]
        line  9: unnamed unused
        line 10: unnamed unused [output]
        line 11: unnamed unused
        line 12: unnamed unused
        line 13: unnamed unused
        line 14: unnamed unused
        line 15: unnamed unused [output]
GPIO chip: gpiochip7, "xra1403", 16 GPIO lines
        line  0: unnamed unused
        line  1: unnamed unused
        line  2: unnamed unused
        line  3: unnamed unused
        line  4: unnamed unused
        line  5: unnamed unused
        line  6: unnamed unused
        line  7: unnamed unused
        line  8: unnamed unused
        line  9: unnamed unused
        line 10: unnamed unused
        line 11: unnamed unused
        line 12: unnamed unused
        line 13: unnamed unused
        line 14: unnamed unused
        line 15: unnamed unused

3.1 `gpio-hammer`

root@csmon ppd:~# gpio-hammer -n gpiochip8 -o0 -o1 -o2 -o3
Hammer lines [0, 1, 2, 3] on gpiochip8, initial states: [0, 0, 0, 0]
[\] [0: 0, 1: 0, 2: 0, 3: 0]
...
[\] [0: 1, 1: 1, 2: 1, 3: 1]

When using `gpio-hammer` I also attached an oscilloscope to one of the pins and I was
able to monitor and validate the GPIO status.


Changes since v2: - improve the commit message by removing the "sysfs"
                    dependency and be more clear.
                  - include "seq_file.h" header.
    Note: documentation patches were accepted already.

Changes since v1: - use regmap for driver
                  - small changes to documentation


Nandor Han (2):
  gpio - Add EXAR XRA1403 SPI GPIO expander driver
  Add XRA1403 support to MAINTAINERS file

 MAINTAINERS                 |   8 ++
 drivers/gpio/Kconfig        |   5 +
 drivers/gpio/Makefile       |   1 +
 drivers/gpio/gpio-xra1403.c | 237 ++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 251 insertions(+)
 create mode 100644 drivers/gpio/gpio-xra1403.c

-- 
2.10.1