pinctrl: mediatek: Fix EINT pins input debounce time configuration

The External Interrupt Controller (EINTC) on all of the supported
MediaTek SoCs does support input debouncing, but not all of them
index the debounce time values (DBNC_SETTING registers) the same way.

Before this change, in some cases, as an example, requesting a debounce
time of 16 milliseconds would mistakenly set the relative DBNC_SETTING
register to 0x2, resulting in a way shorter debounce time of 500uS.

To fix the aforementioned issue, define three different debounce_time
arrays, reflecting the correct register index for each value and for
each register index variant, and make sure that each SoC pinctrl
driver uses the right one.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20221111094106.18486-1-angelogioacchino.delregno@collabora.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

pinctrl: mt7622: drop pwm ch7 as mt7622 only has 6 channels

mt7622 is reported by mediatek to have only 6 pwm channels
so drop pindefines for 7th channel

Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
Acked-by: Sean Wang <sean.wang@kernel.org>
Link: https://lore.kernel.org/r/20201016204019.2606-4-linux@fw-web.de
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

pinctrl: mediatek: mt7622: add antsel pins/groups

These pins are named ANTSEL[0~29] in datasheet and are used by wmac for
various functions.

Signed-off-by: Chuanhong Guo <gch981213@gmail.com>
Link: https://lore.kernel.org/r/20200922164159.120920-1-gch981213@gmail.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

pinctrl: mediatek: extend struct mtk_pin_desc which per-pin driver depends on

Because the pincrl-mtk-common.c is an implementation for per-pin binding,
its pin descriptor includes more information than pinctrl-mtk-common-v2
so far can support. So, we complement these data before writing a driver
using pincrl-mtk-common-v2.c for per-pin binding. By the way, the size of
struct mtk_pin_desc would be larger than struct pinctrl_pin_desc can hold,
so it's necessary to have a copy before the pins information is being
registered into the core.

Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

pinctrl: mediatek: add multiple register bases support to pinctrl-mtk-common-v2.c

Certain SoC own multiple register base for accessing each pin groups,
it's easy to be done with extend struct mtk_pin_field_calc to support
the kind of SoC such as MT8183.

Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

pinctrl: mediatek: add ies register support to pinctrl-mtk-common-v2.c

Certain SoCs have to program an extra IES register to configure input
enabled mode so that we add it in the existing path as an option.

Signed-off-by: Ryder.Lee <ryder.lee@mediatek.com>
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

pinctrl: mediatek: add pull related support to pinctrl-mtk-common-v2.c

Put pull control support related functions to pinctrl-mtk-common-v2.c
as these operations might be different by chips and allow different
type of driver to reuse them.

Signed-off-by: Ryder.Lee <ryder.lee@mediatek.com>
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

pinctrl: mediatek: add driving strength related support to pinctrl-mtk-common-v2.c

Put driving strength support related functions to pinctrl-mtk-common-v2.c
as these operations might be different by chips and allow different type
of driver to reuse them.

Signed-off-by: Ryder.Lee <ryder.lee@mediatek.com>
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

pinctrl: mediatek: extend struct mtk_pin_soc to pinctrl-mtk-common-v2.c

Add two parameters gpio_m and eint_m for configuring GPIO mode and EINT
mode, they might be varying depend on SoC.

Signed-off-by: Ryder.Lee <ryder.lee@mediatek.com>
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

pinctrl: mediatek: extend struct mtk_pin_desc to pinctrl-mtk-common-v2.c

This patch introduces a data structure mtk_pin_desc, which is used to
provide information per pin characteristic such as driving current,
eint number and a driving index, that is used to lookup table describing
the details about the groups of driving current by which the pin is able
to adjust the driving strength so that the driver could get the
appropriate driving group when calls .pin_config_get()/set().

Signed-off-by: Ryder.Lee <ryder.lee@mediatek.com>
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

pinctrl: mediatek: extend struct mtk_pin_field_calc to pinctrl-mtk-common-v2.c

This patch adds members sz_reg fixed in struct mtk_pin_field_calc

- The 'fixed' is used to represent the consecutive pins share the same
bits within the same register with the 1st pin so that it can largely
reduce the entry size a bit.

- The 'sz_reg' is used to indicate the range of bits we use in a register
that may vary by SoC

The above changes make the code more generic and this is useful as there
might be other existing or future chips all use the same logic to access
their register set and then being a little more abstract could help in the
long run.

Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

pinctrl: mediatek: add pinctrl-moore that implements the generic pinctrl dt-bindings

Add a generic driver pinctrl-moore.c for MT762x SoC and any other SoC
that would like to use generic dt-binding. The patch is furtherly
refactored from pinctrl-mt7622.c that totally uses the functions back by
the generic pinctrl core such as GENERIC_PINCONF, GENERIC_PINCTRL_GROUPS,
and GENERIC_PINMUX_FUNCTIONS and its binding also completely follows up
pinctrl-bindings.txt in Documentation/devicetree/bindings/pinctrl/ to
implement.

Signed-off-by: Ryder.Lee <ryder.lee@mediatek.com>
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

pinctrl: mediatek: add pinctrl-mtk-common-v2 for all MediaTek pinctrls

Irregular register arrangement and distinct logic access from various
MediaTek SoCs would cause pinctrl-mtk-common to bloat and really hard to
maintain in the future so that the patch creates pinctrl-mtk-common-v2
based on the core of mt7622-pinctrl.

The goals pinctrl-mtk-common-v2 want to achieve are to hopefully support
all of MediaTek SoCs, and two kinds of dt-bindings being supported,
Linux generic pinctrl dt-binding mt7622 supports and MediaTek per-pin
dt-binding the other SoCs support the MT8183 and MT6765 incline to make
use of.

The patch starts to refactor MT7622 pinctrl driver first with splitting
out these portable ways from there such as table-based register operation
and drive strength control that is common in both kinds of driver.

Signed-off-by: Ryder.Lee <ryder.lee@mediatek.com>
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

pinctrl: Include <linux/gpio/driver.h> nothing else

These drivers are GPIO drivers, and the do not need to use the
legacy header in <linux/gpio.h>, go directly for
<linux/gpio/driver.h> instead.

Replace any use of GPIOF_* with 0/1, these flags are for
consumers, not drivers.

Get rid of a few gpio_to_irq() users that was littering
around the place, use local callbacks or avoid using it at
all.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

pinctrl: mt7622: Fix probe fail by misuse the selector

After the commit acf137951367 ("pinctrl: core: Return selector to the
pinctrl driver") and the commit 47f1242d19c3 ("pinctrl: pinmux: Return
selector to the pinctrl driver"), it's necessary to add the fixes
needed for the pin controller drivers to use the appropriate returned
selector for a negative error number returned in case of the fail at
these functions. Otherwise, the driver would have a failed probe and
that causes boot message cannot correctly output and devices fail
to acquire their own pins.

Cc: Kevin Hilman <khilman@baylibre.com>
Fixes: acf137951367 ("pinctrl: core: Return selector to the pinctrl driver")
Fixes: 47f1242d19c3 ("pinctrl: pinmux: Return selector to the pinctrl driver")
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

pinctrl: mt7622: mark expected switch fall-through

In preparation to enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.

Warning level 2 was used: -Wimplicit-fallthrough=2

Addresses-Coverity-ID: 1463284 ("Missing break in switch")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

pinctrl: mt7622: fix a kernel panic when gpio-hog is being applied

When we are explicitly using GPIO hogging mechanism in the pinctrl node,
such as:

&pio {
line_input {
gpio-hog;
gpios = <95 0>, <96 0>, <97 0>;
input;
};
};

A kernel panic happens at dereferencing a NULL pointer: In this case, the
drvdata is still not setup properly yet when it is being accessed.

A better solution for fixing up this issue should be we should obtain the
private data from struct gpio_chip using a specific gpiochip_get_data
instead of a generic dev_get_drvdata.

[ 0.249424] Unable to handle kernel NULL pointer dereference at virtual
address 000000c8
[ 0.257818] Mem abort info:
[ 0.260704] ESR = 0x96000005
[ 0.263869] Exception class = DABT (current EL), IL = 32 bits
[ 0.270011] SET = 0, FnV = 0
[ 0.273167] EA = 0, S1PTW = 0
[ 0.276421] Data abort info:
[ 0.279398] ISV = 0, ISS = 0x00000005
[ 0.283372] CM = 0, WnR = 0
[ 0.286440] [00000000000000c8] user address but active_mm is swapper
[ 0.293027] Internal error: Oops: 96000005 [#1] PREEMPT SMP
[ 0.298795] Modules linked in:
[ 0.301958] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.16.0-rc1+ #389
[ 0.308716] Hardware name: MediaTek MT7622 RFB1 board (DT)
[ 0.314396] pstate: 80000005 (Nzcv daif -PAN -UAO)
[ 0.319362] pc : mtk_hw_pin_field_get+0x28/0x118
[ 0.324140] lr : mtk_hw_set_value+0x30/0x104
[ 0.328557] sp : ffffff800801b6d0
[ 0.331983] x29: ffffff800801b6d0 x28: ffffff80086b7970
[ 0.337484] x27: 0000000000000000 x26: ffffff80087b8000
[ 0.342986] x25: 0000000000000000 x24: ffffffc00324c230
[ 0.348487] x23: 0000000000000003 x22: 0000000000000000
[ 0.353988] x21: ffffff80087b8000 x20: 0000000000000000
[ 0.359489] x19: 0000000000000054 x18: 00000000fffff7c0
[ 0.364990] x17: 0000000000006300 x16: 000000000000003f
[ 0.370492] x15: 000000000000000e x14: ffffffffffffffff
[ 0.375993] x13: 0000000000000000 x12: 0000000000000020
[ 0.381494] x11: 0000000000000006 x10: 0101010101010101
[ 0.386995] x9 : fffffffffffffffa x8 : 0000000000000007
[ 0.392496] x7 : ffffff80085d63f8 x6 : 0000000000000003
[ 0.397997] x5 : 0000000000000054 x4 : ffffffc0031eb800
[ 0.403499] x3 : ffffff800801b728 x2 : 0000000000000003
[ 0.409000] x1 : 0000000000000054 x0 : 0000000000000000
[ 0.414502] Process swapper/0 (pid: 1, stack limit = 0x000000002a913c1c)
[ 0.421441] Call trace:
[ 0.423968] mtk_hw_pin_field_get+0x28/0x118
[ 0.428387] mtk_hw_set_value+0x30/0x104
[ 0.432445] mtk_gpio_set+0x20/0x28
[ 0.436052] mtk_gpio_direction_output+0x18/0x30
[ 0.440833] gpiod_direction_output_raw_commit+0x7c/0xa0
[ 0.446333] gpiod_direction_output+0x104/0x114
[ 0.451022] gpiod_configure_flags+0xbc/0xfc
[ 0.455441] gpiod_hog+0x8c/0x140
[ 0.458869] of_gpiochip_add+0x27c/0x2d4
[ 0.462928] gpiochip_add_data_with_key+0x338/0x5f0
[ 0.467976] mtk_pinctrl_probe+0x388/0x400
[ 0.472217] platform_drv_probe+0x58/0xa4
[ 0.476365] driver_probe_device+0x204/0x44c
[ 0.480783] __device_attach_driver+0xac/0x108
[ 0.485384] bus_for_each_drv+0x7c/0xac
[ 0.489352] __device_attach+0xa0/0x144
[ 0.493320] device_initial_probe+0x10/0x18
[ 0.497647] bus_probe_device+0x2c/0x8c
[ 0.501616] device_add+0x2f8/0x540
[ 0.505226] of_device_add+0x3c/0x44
[ 0.508925] of_platform_device_create_pdata+0x80/0xb8
[ 0.514245] of_platform_bus_create+0x290/0x3e8
[ 0.518933] of_platform_populate+0x78/0x100
[ 0.523352] of_platform_default_populate+0x24/0x2c
[ 0.528403] of_platform_default_populate_init+0x94/0xa4
[ 0.533903] do_one_initcall+0x98/0x130
[ 0.537874] kernel_init_freeable+0x13c/0x1d4
[ 0.542385] kernel_init+0x10/0xf8
[ 0.545903] ret_from_fork+0x10/0x18
[ 0.549603] Code: 900020a1 f9400800 911dcc21 1400001f (f9406401)
[ 0.555916] ---[ end trace de8c34787fdad3b3 ]---
[ 0.560722] Kernel panic - not syncing: Attempted to kill init!
exitcode=0x0000000b
[ 0.560722]
[ 0.570188] SMP: stopping secondary CPUs
[ 0.574253] ---[ end Kernel panic - not syncing: Attempted to kill
init! exitcode=0x0000000b
[ 0.574253]

Cc: stable@vger.kernel.org
Fixes: d6ed93551320 ("pinctrl: mediatek: add pinctrl driver for MT7622 SoC")
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

pinctrl: mt7622: stop using the deprecated pinctrl_add_gpio_range

If the pinctrl node has the gpio-ranges property, the range will be added
by the gpio core and doesn't need to be added by the pinctrl driver.

But for keeping backward compatibility, an explicit pinctrl_add_gpio_range
is still needed to be called when there is a missing gpio-ranges in pinctrl
node in old dts files.

Cc: stable@vger.kernel.org
Fixes: d6ed93551320 ("pinctrl: mediatek: add pinctrl driver for MT7622 SoC")
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

pinctrl: mt7622: fix that pinctrl_claim_hogs cannot work

To allow claiming hogs by pinctrl, we cannot enable pinctrl until all
groups and functions are being added done. Also, it's necessary that
the corresponding gpiochip is being added when the pinctrl device is
enabled.

Cc: stable@vger.kernel.org
Fixes: d6ed93551320 ("pinctrl: mediatek: add pinctrl driver for MT7622 SoC")
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

pinctrl: mt7622: fix initialization sequence between eint and gpiochip

Because gpichip applied in the driver must depend on mtk eint to implement
the input data debouncing and the translation between gpio and irq, it's
better to keep logic consistent with mtk eint being built prior to gpiochip
being added.

Cc: stable@vger.kernel.org
Fixes: e6dabd38d8e7 ("pinctrl: mediatek: add EINT support to MT7622 SoC")
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

pinctrl: mt7622: fix error path on failing at groups building

It should be to return an error code when failing at groups building.

Cc: stable@vger.kernel.org
Fixes: d6ed93551320 ("pinctrl: mediatek: add pinctrl driver for MT7622 SoC")
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

pinctrl: mt7622: fix a kernel panic when pio don't work as EINT controller

The function, external interrupt controller, is made as an optional to
mt7622 pinctrl. But if we don't want pio behaves as an external interrupt
controller, it would lead to hw->eint not be created properly and then
will cause 'kernel NULL pointer' issue when gpiochip try to call .to_irq
or .set_config. To fix it, check hw->eint before accessing the member.

[ 1.339494] Unable to handle kernel NULL pointer dereference at virtual
address 00000010
[ 1.347857] Mem abort info:
[ 1.350742] ESR = 0x96000005
[ 1.353905] Exception class = DABT (current EL), IL = 32 bits
[ 1.360024] SET = 0, FnV = 0
[ 1.363185] EA = 0, S1PTW = 0
[ 1.366431] Data abort info:
[ 1.369405] ISV = 0, ISS = 0x00000005
[ 1.373363] CM = 0, WnR = 0
[ 1.376437] [0000000000000010] user address but active_mm is swapper
[ 1.383005] Internal error: Oops: 96000005 [#1] PREEMPT SMP
[ 1.388748] Modules linked in:
[ 1.391897] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.16.0-rc1+ #344
[ 1.398625] Hardware name: MediaTek MT7622 RFB1 board (DT)
[ 1.404279] pstate: 80000005 (Nzcv daif -PAN -UAO)
[ 1.409221] pc : mtk_eint_find_irq+0x8/0x24
[ 1.413532] lr : mtk_gpio_to_irq+0x20/0x28
[ 1.417749] sp : ffffff800801baf0
[ 1.421161] x29: ffffff800801baf0 x28: ffffff8008792f40
[ 1.426637] x27: ffffff800886b000 x26: ffffff8008615620
[ 1.432113] x25: ffffffc00e4dbdc8 x24: ffffff80087b8000
[ 1.437589] x23: ffffffc00325a000 x22: ffffffc00325a010
[ 1.443066] x21: ffffffc0033dec18 x20: 00000000ffffffea
[ 1.448542] x19: ffffffc00e4db800 x18: 0000000000000130
[ 1.454018] x17: 000000000000000e x16: 0000000000000007
[ 1.459494] x15: ffffff80085ee000 x14: 0000000000000001
[ 1.464970] x13: 0000000000000001 x12: 0000000000000010
[ 1.470446] x11: 0101010101010101 x10: 0000000000000880
[ 1.475922] x9 : ffffff800801b990 x8 : ffffffc0030688e0
[ 1.481399] x7 : ffffff80080c0660 x6 : ffffffc00e4dbbb0
[ 1.486875] x5 : 0000000000000000 x4 : 0000000000000000
[ 1.492351] x3 : ffffff80082a92f4 x2 : 00000000fffffffa
[ 1.497826] x1 : 0000000000000051 x0 : 0000000000000000
[ 1.503305] Process swapper/0 (pid: 1, stack limit = 0x0000000054e053bd)
[ 1.510210] Call trace:
[ 1.512727] mtk_eint_find_irq+0x8/0x24
[ 1.516677] mtk_gpio_to_irq+0x20/0x28
[ 1.520539] gpiod_to_irq+0x48/0x60
[ 1.524135] mmc_gpiod_request_cd_irq+0x3c/0xc4
[ 1.528804] mmc_start_host+0x6c/0x8c
[ 1.532575] mmc_add_host+0x58/0x7c
[ 1.536168] msdc_drv_probe+0x4fc/0x67c
[ 1.540121] platform_drv_probe+0x58/0xa4
[ 1.544251] driver_probe_device+0x204/0x44c
[ 1.548649] __driver_attach+0x84/0xf8
[ 1.552512] bus_for_each_dev+0x68/0xa0
[ 1.556461] driver_attach+0x20/0x28
[ 1.560142] bus_add_driver+0xec/0x240
[ 1.564002] driver_register+0x98/0xe4
[ 1.567863] __platform_driver_register+0x48/0x50
[ 1.572711] mt_msdc_driver_init+0x18/0x20
[ 1.576932] do_one_initcall+0x98/0x130
[ 1.580886] kernel_init_freeable+0x13c/0x1d4
[ 1.585375] kernel_init+0x10/0xf8
[ 1.588879] ret_from_fork+0x10/0x18
[ 1.592564] Code: a8c67bfd d65f03c0 a9bf7bfd 910003fd (f9400800)
[ 1.598849] ---[ end trace 4bbcb7bc30e98492 ]---
[ 1.603677] Kernel panic - not syncing: Attempted to kill init!
exitcode=0x0000000b
[ 1.603677]

cc: Kevin Hilman <khilman@baylibre.com>
Cc: stable@vger.kernel.org
Fixes: e6dabd38d8e7 ("pinctrl: mediatek: add EINT support to MT7622 SoC")
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

pinctrl: mediatek: add EINT support to MT7622 SoC

Add EINT support to MT7622 SoC and the support is made as just an option
to MT7622 pinctrl.

Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

pinctrl: mediatek: mt7622: align error handling of mtk_hw_get_value call

Make consistent error handling of all mtk_hw_get_value occurrences using
propagating error code from the internal instead of creating a new one.

Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

pinctrl: mediatek: mt7622: fix potential uninitialized value being returned

commit d6ed93551320 ("pinctrl: mediatek: add pinctrl driver for MT7622
SoC") leads to the following static checker warning:

drivers/pinctrl/mediatek/pinctrl-mt7622.c:1419 mtk_gpio_get()
error: uninitialized symbol 'value'.
1412 static int mtk_gpio_get(struct gpio_chip *chip, unsigned int gpio)
1413 {
1414 struct mtk_pinctrl *hw = dev_get_drvdata(chip->parent);
1415 int value;
1416
1417 mtk_hw_get_value(hw, gpio, PINCTRL_PIN_REG_DI, &value);
^^^^^^^^^^^^^^^^
1418
1419 return !!value;
1420 }

The appropriate error handling must be added to avoid the potential error
caused by uninitialized value being returned.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

pinctrl: mediatek: add pinctrl driver for MT7622 SoC

Add support for pinctrl on MT7622 SoC. The IO core found on the SoC has
the registers for pinctrl, pinconf and gpio mixed up in the same register
range. However, the IO core for the MT7622 SoC is completely distinct from
anyone of previous MediaTek SoCs which already had support, such as
the hardware internal, register address map and register detailed
definition for each pin.

Therefore, instead, the driver is being newly implemented by reusing
generic methods provided from the core layer with GENERIC_PINCONF,
GENERIC_PINCTRL_GROUPS, and GENERIC_PINMUX_FUNCTIONS for the sake of code
simplicity and rid of superfluous code. Where the function of pins
determined by groups is utilized in this driver which can help developers
less confused with what combinations of pins effective on the SoC and even
reducing the mistakes during the integration of those relevant boards.

As the gpio_chip handling is also only a few lines, the driver also
implements the gpio functionality directly through GPIOLIB.

Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Reviewed-by: Biao Huang <biao.huang@mediatek.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>