The use of stack Variable Length Arrays needs to be avoided, as they
can be a vector for stack exhaustion, which can be both a runtime bug
(kernel Oops) or a security flaw (overwriting memory beyond the
stack). Also, in general, as code evolves it is easy to lose track of
how big a VLA can get. Thus, we can end up having runtime failures
that are hard to debug. As part of the directive[1] to remove all VLAs
from the kernel, and build with -Wvla.

Currently driver is using a VLA declared using the number of descriptors.  This
array is used to store integer values and is later used as an argument to
`gpiod_set_array_value_cansleep()` This can be avoided by using
`kmalloc_array()` to allocate memory for the array of integer values.  Memory is
free'd before return from function.

>From the code it appears that it is safe to sleep so we can use GFP_KERNEL
(based _cansleep() suffix of function `gpiod_set_array_value_cansleep()`.

It can be expected that this patch will result in a small increase in overhead
due to the use of `kmalloc_array()`

[1] https://lkml.org/lkml/2018/3/7/621

Signed-off-by: Tobin C. Harding <me@tobin.cc>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

If the optional power-off-delay-us property is found, insert the
corresponding delay after asserting the GPIO during power off. This enables
a graceful shutdown sequence for some devices.

Cc: linux-mmc@vger.kernel.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>

Some devices need a while to boot their firmware after providing clks /
de-asserting resets before they are ready to receive sdio commands.

This commits adds a post-power-on-delay-ms devicetree property to
mmc-pwrseq-simple for use with such devices.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

simple-pwrseq and emmc-pwrseq drivers rely on platform_device
structure from of_find_device_by_node(), this works mostly. But, as there
is no driver associated with this devices, cases like default/init pinctrl
setup would never be performed by pwrseq. This becomes problem when the
gpios used in pwrseq require pinctrl setup.

Currently most of the common pinctrl setup is done in
drivers/base/pinctrl.c by pinctrl_bind_pins().

There are two ways to solve this issue on either convert pwrseq drivers
to a proper platform drivers or copy the exact code from
pcintrl_bind_pins(). I prefer converting pwrseq to proper drivers so that
other cases like setting up clks/parents from dt would also be possible.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

This patch adds to_pwrseq_simple() macro to make the code more readable.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

Signed-off-by: Peter Chen <peter.chen@freescale.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

The DT binding doc says reset-gpios is an optional property but the code
currently bails out if it is omitted.

This is a regression since it breaks previously working device trees.
Fix it by restoring the original documented behaviour.

Fixes: ce037275861e ("mmc: pwrseq_simple: use GPIO descriptors array API")
Tested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Martin Fuzzey <mfuzzey@parkeon.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

The mmc_pwrseq_ops structures are never modified, so declare them as const.

Done with the help of Coccinelle.

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

The simple power sequence provider sets a value for multiple GPIOs in one
go so it is better to use the API already provided by the GPIO descriptor
API instead of open coding the same logic.

Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

The alloc() and free() hooks required each pwrseq implementation to set
host->pwrseq themselves. This is error-prone and could be done at a
higher level if alloc() was changed to return a pointer to a struct
mmc_pwrseq instead of an error code.

This patch performs this change and moves the burden of maintaining
host->pwrseq from the power sequence hooks to the pwrseq code.

Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>