• Martin Blumenstingl's avatar
    pinctrl: meson: meson8b: fix requesting GPIOs greater than GPIOZ_3 · 55af415b
    Martin Blumenstingl authored
    Meson8b is a cost reduced variant of the Meson8 SoC. It's package size
    is smaller than Meson8.
    Unfortunately there are a few key differences which cannot be seen
    without close inspection of the code and the public S805 datasheet:
    - the GPIOX bank is missing the GPIOX_12, GPIOX_13, GPIOX_14 and
      GPIOX_15 GPIOs
    - the GPIOY bank is missing the GPIOY_2, GPIOY_4, GPIOY_5, GPIOY_15 and
      GPIOY_16 GPIOs
    - the GPIODV bank is missing all GPIOs except GPIODV_9, GPIODV_24,
      GPIODV_25, GPIODV_26, GPIODV_27, GPIODV_28 and GPIODV_29
    - the GPIOZ bank is missing completely
    - there is a new GPIO bank called "DIF"
    
    This means that Meson8b only has 83 actual GPIO lines. Without any holes
    there would be 130 GPIO lines in total (120 are inherited from Meson8
    plus 10 new from the DIF bank).
    
    GPIOs greater GPIOZ_3 (whose ID is 83 - as a reminder: this is exactly
    the number of actual GPIO lines on Meson8b and also the value of
    meson8b_cbus_pinctrl_data.num_pins) cannot berequested. Using CARD_6
    (which used ID 100 prior to this patch, "base of the GPIO controller was
    382) as an example:
    $ echo 482 > /sys/class/gpio/export
    export_store: invalid GPIO 482
    
    This removes all non-existing pins from to dt-bindings header file
    (include/dt-bindings/gpio/meson8b-gpio.h). This allows us to have a
    consecutive numbering for the GPIO #defines (GPIOY_2 doesn't exist for
    example, so previously the GPIOY_3 ID was "GPIOY_1 + 2", after this
    patch it is "GPIOY_1 + 1"). As a nice side-effect this means that we get
    compile-time (instead of runtime) errors if Meson8b .dts uses a pin that
    only exists on Meson8.
    
    Additionally the pinctrl-meson8b driver has to be updated to handle this
    new GPIO numbering. By default a struct meson_bank only handles GPIO
    banks where the pins are numbered consecutively because it calculates
    the bit offsets based on the GPIO IDs.
    This is solved by  taking the original BANK() definition and splitting it
    into consecutive subsets (X0..11 and X16..21). The bit offsets for each
    new bank includes the skipped GPIOs (the definition of the "X0..11" bank
    is identical to the old "X" bank apart from the "last IRQ" field, the
    definition of the new, split "X16..21" bank takes the original "X" bank
    and adds 16 - the start of the new split bank - to the "first IRQ",
    pullen bit, pull bit, dir bit, out bit and in bit).
    
    Commit 984cffde ("pinctrl: Fix gpio/pin mapping for Meson8b")
    fixed the same issue by setting "ngpio" (of the gpio_chip) to 130.
    Unfortunately this broke in db80f0e1 ("pinctrl: meson: get rid of
    unneeded domain structures").
    The solution from this patch was considered to be better than the
    previous attempt at fixing this because it provides compile-time error
    checking for the GPIOs that exist on Meson8 but don't exist on Meson8b.
    
    The following pins were tested on an Odroid-C1 using the sysfs GPIO
    interface checking that their value (high or low) could be read:
    - GPIOX_0, GPIOX_1, GPIOX_2, GPIOX_3, GPIOX_4, GPIOX_5, GPIOX_6,
      GPIOX_7, GPIOX_8, GPIOX_9, GPIOX_10, GPIOX_11, GPIOX_18, GPIOX_19,
      GPIOX_20, GPIOX_21
    - GPIOY_3, GPIOY_7, GPIOY_8
    (some of these had to be pulled up because they were low by default,
    others were high by default so these had to be pulled down)
    Reported-by: default avatarLinus Lüssing <linus.luessing@c0d3.blue>
    Suggested-by: default avatarJerome Brunet <jbrunet@baylibre.com>
    Signed-off-by: default avatarMartin Blumenstingl <martin.blumenstingl@googlemail.com>
    Reviewed-by: default avatarJerome Brunet <jbrunet@baylibre.com>
    Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
    55af415b
pinctrl-meson8b.c 28.9 KB