[PATCH v4 0/9] Migrate i8255 GPIO drivers to regmap API

[William Breathitt Gray <william.gray@xxxxxxxxxx>]

Changes in v4:
 - Align trailing '\' characters in macros to same column in 104-dio-48e
   and 104-idi-48
 - Remove superfluous trailing commas in macros in 104-dio-48e and
   104-idi-48
 - Simplify dio48e_handle_mask_sync() regmap_* calls error checks to
   return error codes directly
 - Refactor dio48e_irq_init_hw() for regmap and comment about spurious
   interrupts; in theory this should be enough to prevent spurious
   interrupts before the system is ready, but we can pass this function
   as a callback where needed in the future
 - Cleanup '{0}' as '{}' in probe() callbacks for 104-dio-48e,
   104-idi-48, and gpio-mm
 - Utilize dev_err_probe() in probe() callbacks for 104-dio-48e and
   104-idi-48
 - Provide convenience comments for idi48_regmap_irqs initialization
   list
 - Replace header includes with forward declarations in gpio-i8255.h

The regmap API supports IO port accessors so we can take advantage of
regmap abstractions rather than handling access to the device registers
directly in the driver. The 104-dio-48e and gpio-mm modules depend on
the i8255 library and are thus updated accordingly.

The 104-IDI-48 is hardwired as an input-only device. Because the i8255
control registers are not exposed on the 104-IDI-48, the i8255 library
doesn't provide much benefit here. In this case it's simpler to utilize
the gpio_regmap API directly, so this patch series does such and removes
the i8255 library dependency from the 104-idi-48 module.

The first patch in this series adjusts gpio_regmap to always set
gpio_chip get_direction. This patch is mostly independent of the rest of
the patches in the series and can be picked up separately if desired.
I'm including it here because it allows the input-only 104-idi-48 driver
to continue reporting offset directions after migrating to gpio_regmap.

A handle_mask_sync() callback is introduced for the regmap_irq API. This
is used by the 104-dio-48e driver to handle its enable/disable interrupt
functionality. The 104-DIO-48E has a single register to handle
enabling/disabling interrupts: a write of any value to this register
enables interrupts, while any read disables interrupts.

By leveraging the gpio_regmap API, the i8255 library is reduced to
simply a devm_i8255_regmap_register() function, a configuration
structure struct i8255_regmap_config, and a helper macro
i8255_volatile_regmap_range() provided to simplify volatile PPI register
hinting for the regmap.

The regmap_irq API is leveraged by the 104-idi-48 and 104-dio-48e
modules to support their IRQ functionality. Do their respective regmap
configurations need use_hwlock set to true in this case, or is adequate
locking already handled by the regmap_irq API?

William Breathitt Gray (9):
  gpio: regmap: Always set gpio_chip get_direction
  regmap-irq: Add handle_mask_sync() callback
  gpio: 104-dio-48e: Migrate to the regmap-irq API
  gpio: 104-idi-48: Migrate to the regmap-irq API
  gpio: 104-idi-48: Migrate to gpio-regmap API
  gpio: i8255: Migrate to gpio-regmap API
  gpio: 104-dio-48e: Migrate to regmap API
  gpio: gpio-mm: Migrate to regmap API
  gpio: i8255: Remove unused legacy interface

 drivers/base/regmap/regmap-irq.c |  44 +++-
 drivers/gpio/Kconfig             |   5 +-
 drivers/gpio/gpio-104-dio-48e.c  | 391 ++++++++++---------------------
 drivers/gpio/gpio-104-idi-48.c   | 336 +++++++++-----------------
 drivers/gpio/gpio-gpio-mm.c      | 154 +++---------
 drivers/gpio/gpio-i8255.c        | 320 +++++++------------------
 drivers/gpio/gpio-i8255.h        |  54 ++---
 drivers/gpio/gpio-regmap.c       |   7 +-
 include/linux/regmap.h           |   5 +
 9 files changed, 416 insertions(+), 900 deletions(-)


base-commit: 3b7c7478eda00945987d45f902bc3942c89243d3
-- 
2.38.1