Since this device is only partially initialized by the irqchip driver,
we need to mark the fwnode device as not initialized. This is to let
fw_devlink know that the device will be completely initialized at a
later point. That way, fw_devlink will continue to defer the probe of
the power domain consumers till the power domain driver successfully
binds to the struct device and completes the initialization of the
device.
Signed-off-by: Saravana Kannan <saravanak@google.com>
Tested-by: Douglas Anderson <dianders@chromium.org>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Luca Weiss <luca.weiss@fairphone.com> # qcom/sm7225-fairphone-fp4
Link: https://lore.kernel.org/r/20230207014207.1678715-11-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To keep the power domain on if usb remote wakeup is enabled, add the
GENPD_FLAG_ACTIVE_WAKEUP for otg1/2 of imx8mm/n.
Signed-off-by: Li Jun <jun.li@nxp.com>
Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
In case the power domain clock are ungated before the reset is asserted,
the system might freeze completely. This is likely due to a device is an
undefined state being attached to bus, which sporadically leads to a bus
hang. Assert the reset before the clock are enabled to assure the device
is in defined state before being attached to bus.
Fixes: fe58c887fb ("soc: imx: gpcv2: add support for optional resets")
Signed-off-by: Marek Vasut <marex@denx.de>
Reviewed-by: Fabio Estevam <festevam@denx.de>
Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Make debugging of power management issues easier by printing the reason
why a regulator fails to be enabled or disabled.
Signed-off-by: Martin Kepplinger <martin.kepplinger@puri.sm>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
This adds driver support for all the GPC power domains found on
the i.MX8MP SoC.
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
The PGC control registers in the shared (not per-PGC) region of the
GPC address space have different offsets on i.MX8MP to make space for
additional interrupt control registers.
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
The imx_pgc_power_down() starts by enabling the domain clocks, and thus
disables them in the error path. Commit 18c98573a4 ("soc: imx: gpcv2:
add domain option to keep domain clocks enabled") made the clock enable
conditional, but forgot to add the same condition to the error path.
This can result in a clock enable/disable imbalance. Fix it.
Fixes: 18c98573a4 ("soc: imx: gpcv2: add domain option to keep domain clocks enabled")
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
The dispmix will be needed for the blkctl driver, so add it
to the gpcv2.
Signed-off-by: Adam Ford <aford173@gmail.com>
Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Like the i.MX8MM, keep the gpumix clocks running when the
domain is active.
Signed-off-by: Adam Ford <aford173@gmail.com>
Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Enable the vpu-h1 clock when the domain is active because reading
or writing to the VPU-H1 IP block cause the system to hang.
Fixes: 656ade7aa4 ("soc: imx: gpcv2: keep i.MX8M* bus clocks enabled")
Signed-off-by: Adam Ford <aford173@gmail.com>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
In case the following power domain sequence happens, iMX8M Mini always hangs:
gpumix:on -> gpu:on -> gpu:off -> gpu:on
This is likely due to another quirk of the GPC block. This situation can be
prevented by always synchronously powering off both the domain and MIX domain.
Make it so. This turns the aforementioned sequence into:
gpumix:on -> gpu:on -> gpu:off -> gpumix:off -> gpumix:on -> gpu:on
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Frieder Schrempf <frieder.schrempf@kontron.de>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: NXP Linux Team <linux-imx@nxp.com>
Cc: Peng Fan <peng.fan@nxp.com>
Cc: Shawn Guo <shawnguo@kernel.org>
Acked-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Our usage of runtime PM to control the hierarchy of power domains is
slightly unusual and means that powering up a domain may fail in early
system resume, as runtime PM is still disallowed at this stage.
However the system suspend/resume path takes care of powering down/up
the power domains in the order defined by the device parent/child and
power-domain provider/consumer hierarachy. So we can just runtime
resume all our power-domain devices to allow the power-up to work
properly in the resume path. System suspend will still disable all
domains as intended.
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Acked-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Annotate the domains with bus clocks to keep those clocks enabled
as long as the domain is active.
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Some of the MIX domains are using clocks to drive the bus bridges. Those
must be enabled at all times, as long as the domain is powered up and
they don't have any other consumer than the power domain. Add an option
to keep the clocks attached to a domain enabled as long as the domain
is power up and only disable them after the domain is powered down.
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Some of the GPCv2 power domains are nested inside each other without
visibility to lockdep at the genpd level, as they are in separate
driver instances and don't have a parent/child power-domain relationship.
Add a subclass annotation to the nested domains to let lockdep know that
it is okay to take the genpd lock in a nested fashion.
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
This reverts commit a77ebdd9f553. It turns out that the VPU domain has no
different requirements, even though the downstream ATF implementation seems
to suggest otherwise. Powering on the domain with the reset asserted works
fine. As the changed sequence has caused sporadic issues with the GPU
domains, just revert the change to go back to the working sequence.
Cc: <stable@vger.kernel.org> # 5.14
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Acked-by: Peng Fan <peng.fan@nxp.com>
Tested-by: Adam Ford <aford173@gmail.com> #imx8mm-beacon
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Some board designs don't supply power to all of the power domains,
as they are not used anyways. In that case we must make sure to
not touch those power domains at all, as trying to power up a
domain that has no power supplied to it will obviously end in a
system crash. Allow to disable those domains via the standard DT
status property.
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Reviewed-By: Tim Harvey <tharvey@gateworks.com>
Tested-By: Tim Harvey <tharvey@gateworks.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
To bring up the MX8MM GPU domain, it is necessary to configure both
GPC_PGC_nCTRL(GPU_2D) and GPC_PGC_nCTRL(GPU_3D) registers. Without
this configuration, the system might hang on boot when bringing up
the GPU power domain. This is sporadically observed on multiple
disparate systems.
Add the GPU3D bit into MX8MM GPU domain pgc bitfield, so that both
GPC_PGC_nCTRL(GPU_2D) and GPC_PGC_nCTRL(GPU_3D) registers are
configured when bringing up the GPU domain. This fixes the sporadic
hang.
Reviewed-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Frieder Schrempf <frieder.schrempf@kontron.de>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: NXP Linux Team <linux-imx@nxp.com>
Cc: Peng Fan <peng.fan@nxp.com>
Cc: Shawn Guo <shawnguo@kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
There is currently the MX8MM GPU domain, which is in fact a composite domain
for both GPU2D and GPU3D. To correctly configure this domain, it is necessary
to control both GPC_PGC_nCTRL(GPU_2D) and GPC_PGC_nCTRL(GPU_3D) at the same
time. This is currently not possible.
Turn the domain->pgc from value into bitfield and use for_each_set_bit() to
iterate over all bits set in domain->pgc when configuring GPC_PGC_nCTRL
register array. This way it is possible to configure all GPC_PGC_nCTRL
registers required in a particular domain.
This is a preparatory patch, no functional change.
Reviewed-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Frieder Schrempf <frieder.schrempf@kontron.de>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: NXP Linux Team <linux-imx@nxp.com>
Cc: Peng Fan <peng.fan@nxp.com>
Cc: Shawn Guo <shawnguo@kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
This adds support for the power domains founds on i.MX8MN. The Nano
has fewer domains than the Mini, and the access to some of these domains
is different than that of the Mini, the Mini power domains cannot be
reused.
Signed-off-by: Adam Ford <aford173@gmail.com>
Acked-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
The i.MX8MM VPU power up sequence is a bit special, it must follow:
1. request power up
2. reset assert
3. reset deassert
This change in this patch will not affect other domains, because
the power domain default is in asserted state, unless bootloader
deassert the reset. It also applies to GPU power domain.
Reviewed-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Tested-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
With the BLK-CTL driver now in place, let's add the missing domains.
Tested-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
This adds support for the power domains found on i.MX8MM. The 2D and 3D
GPU domains are abstracted as a single domain in the driver, as they can't
be powered up/down individually due to a shared reset.
Tested-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Reviewed-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Normally the reset for the devices inside the power domain is
triggered automatically from the PGC in the power-up sequencing,
however on i.MX8MM this doesn't work for the GPU power domains.
Add support for triggering the reset explicitly during the power
up sequencing.
Tested-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Reviewed-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Some of the PGC domains only control the handshake with the ADB400
and don't have any power sequence controls. Make such domains work
by allowing the pxx and map bits to be empty and skip all actions
using those controls.
Tested-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Reviewed-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
This allows to nest domains into other power domains and have the
parent domain powered up/down as required by the child domains.
Tested-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Reviewed-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
New reference manuals show that there is actually a status bit for
the ADB400 handshake. Add a poll loop to wait for the ADB400 to
acknowledge our request.
[Peng Fan: i.MX8MM has blk ctl module, the handshake can only finish
after setting blk ctl. The blk ctl driver will set the bus clk bit and
the handshake will finish there. we just add a delay and suppose the
handshake will finish after that.]
Tested-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
The current mixed function to control both power up and power down
sequences is very hard to follow and already contains some sequence
errors like triggering the ADB400 handshake at the wrong time due to
this. Split the function into two, which results in slightly more
code, but is way easier to get right.
Tested-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Reviewed-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Use clk_bulk API to simplify the code a bit. Also add some error
checking to the clk_prepare_enable calls.
Tested-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Reviewed-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
As long as the power domain driver is active we want power control
over the domain (which is what the mapping bit requests), so there
is no point in whacking it for every power control action, simply
set the bit in driver probe and clear it when the driver is removed.
Tested-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Reviewed-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Switch to "goto out..." error handling in domain driver probe to
avoid repeating all the error paths.
Tested-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Reviewed-by: Marek Vasut <marex@denx.de>
Reviewed-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Tested-by: Adam Ford <aford173@gmail.com>
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
dev_err_probe() can reduce code size, uniform error handling and record the
defer probe reason etc., use it to simplify the code.
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Reviewed-by: Guido Günther <agx@sigxcpu.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
This header is included indirectly on arm/arm64 but not on x86 so
CONFIG_COMPILE_TEST breaks. Fix by including <linux/sizes.h> directly.
Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
The current code prints 'ret' (thus 0) while it should use 'err'.
Signed-off-by: Guido Günther <agx@sigxcpu.org>
Reviewed-by: Daniel Baluta <daniel.baluta@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Use the new helper devm_platform_ioremap_resource() which wraps the
platform_get_resource() and devm_ioremap_resource() together, to
simplify the code.
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Reviewed-by: Mukesh Ojha <mojha@codeaurora.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Replace explicit polling loop with a call to
regmap_read_poll_timeout() to avoid code repetition. Also fix
misspelled "failed" while at it.
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: Chris Healy <cphealy@gmail.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Some power domains handled by the GPCv2 driver need to enable the clocks
for devies inside the domain, so that the reset propagation and proper
power-up sequencing happens. Handle them in the same way as on GPCv1.
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Some of the i.MX8MQ domains have an additional control bit in the PU
handshake (HSK) register. Documentation about this bit is a bit sparse
at the moment, but it seems that it controls a power-down request to
the AMBA domain bridge (ADB-400) attached to those domains.
As the documentation doesn't desribe the usage of this bit yet, handle
it in the same way as done in the ATF implementation.
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
The GPCv2 on the Freescale i.MX8MQ SoC works in the same way as the
GPCv2 on the i.MX7, but only controls more power domains with a
different mapping.
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
The valid register ranges are defined by the implemented power domains,
which are different between the individual SoCs where the GPCv2 is used.
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
So we can add i.MX8M support without introducing name clashes.
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
i.MX8MQ and i.MX8MM share same gpc module with i.MX7D, they
can reuse gpcv2 pgc driver for power domain control, this
patch renames all functions and structure definitions started
with "imx7" to "imx", and use .data in imx_gpcv2_dt_ids[] to
pass platform specific power domain data for power domain
driver, thus make gpcv2 pgc driver more generic for i.MX
platforms.
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Acked-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
gpcv2 driver is NOT just used on i.MX7D which has Cortex-A7
cores, but also on i.MX8MQ/i.MX8MM platforms which use Cortex-A53
cores, so let's use A_CORE instread of A7 to avoid confusion.
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Acked-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Correct MIPI/PCIe/USB_HSIC's PGC offset based on
design RTL, the values in the Reference Manual
(Rev. 1, 01/2018 and the older ones) are incorrect.
The correct offset values should be as below:
0x800 ~ 0x83F: PGC for core0 of A7 platform;
0x840 ~ 0x87F: PGC for core1 of A7 platform;
0x880 ~ 0x8BF: PGC for SCU of A7 platform;
0xA00 ~ 0xA3F: PGC for fastmix/megamix;
0xC00 ~ 0xC3F: PGC for MIPI PHY;
0xC40 ~ 0xC7F: PGC for PCIe_PHY;
0xC80 ~ 0xCBF: PGC for USB OTG1 PHY;
0xCC0 ~ 0xCFF: PGC for USB OTG2 PHY;
0xD00 ~ 0xD3F: PGC for USB HSIC PHY;
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Fixes: 03aa12629f ("soc: imx: Add GPCv2 power gating driver")
Acked-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Platform device core assumes the ownership of dev.platform_data as
well as that it is dynamically allocated and it will try to kfree it
as a part of platform_device_release(). Change the code to use
platform_device_add_data() n instead of a pointer to a static memory
to avoid causing a BUG() when calling platform_device_put().
The problem can be reproduced by artificially enabling the error path
of platform_device_add() call (around line 357).
Note that this change also allows us to constify imx7_pgc_domains,
since we no longer need to be able to modify it.
Cc: Stefan Agner <stefan@agner.ch>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
If a regulator requests a deferred probe, the power domain gets
initialized twice. This leads to a list double add (without
list debugging the kernel hangs due to the double add later):
WARNING: CPU: 0 PID: 19 at lib/list_debug.c:31 __list_add_valid+0xbc/0xc4
list_add double add: new=c1229754, prev=c12383b4, next=c1229754.
Initialize the power domain after we get the regulator. Also do
not print an error in case the regulator defers probing.
Cc: Fabio Estevam <fabio.estevam@nxp.com>
Cc: Andrey Smirnov <andrew.smirnov@gmail.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Fixes: 03aa12629f ("soc: imx: Add GPCv2 power gating driver")
Signed-off-by: Stefan Agner <stefan@agner.ch>
Acked-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Tested-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Add code allowing for control of various power domains managed by GPCv2
IP block found in i.MX7 series of SoCs. Power domains covered by this
patch are:
- PCIE PHY
- MIPI PHY
- USB HSIC PHY
- USB OTG1/2 PHY
Support for any other power domain controlled by GPC is not present, and
can be added at some later point.
Testing of this code was done against a PCIe driver.
Cc: yurovsky@gmail.com
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: Fabio Estevam <fabio.estevam@nxp.com>
Cc: Dong Aisheng <dongas86@gmail.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Saravana Kannan