linux-toradex.git/drivers/pinctrl/pinmux.c, branch v3.10.76

pinctrl: move subsystem mutex to pinctrl_dev struct

2013-04-26T15:01:35+00:00

This mutex avoids deadlock in case of use of multiple pin
controllers. Before this modification, by using a global
mutex, deadlock appeared when, for example, a call to
pinctrl_pins_show() locked the pinctrl_mutex, called the
ops->pin_dbg_show of a particular pin controller. If this
pin controller needs I2C access to retrieve configuration
information and I2C driver is using pinctrl to drive its
pins, a call to pinctrl_select_state() try to lock again
pinctrl_mutex which leads to a deadlock.

Notice that the mutex grab from the two direction functions
was moved into pinctrl_gpio_direction().

For several cases, we can't replace pinctrl_mutex by
pctldev->mutex, because at this stage, pctldev is
not accessible :
	- pinctrl_get()/pinctrl_put()
	- pinctrl_register_maps()

So add respectively pinctrl_list_mutex and
pinctrl_maps_mutex in order to protect
pinctrl_list and pinctrl_maps list instead.

Reintroduce pinctrldev_list_mutex in
find_pinctrl_by_of_node(),
pinctrl_find_and_add_gpio_range()
pinctrl_request_gpio(), pinctrl_free_gpio(),
pinctrl_gpio_direction(), pinctrl_devices_show(),
pinctrl_register() and pinctrl_unregister() to
protect pinctrldev_list.

Changes v2->v3:
- Fix a missing EXPORT_SYMBOL_GPL() for pinctrl_select_state().

Changes v1->v2:
- pinctrl_select_state_locked() is removed, all lock mechanism
  is located inside pinctrl_select_state(). When parsing
  the state->setting list, take the per-pin-controller driver
  lock. (Patrice).
- Introduce pinctrldev_list_mutex to protect pinctrldev_list
  in all functions which parse or modify pictrldev_list.
  (Patrice).
- move find_pinctrl_by_of_node() from pinctrl/devicetree.c to
  pinctrl/core.c in order to protect pinctrldev_list.
  (Patrice).
- Sink mutex:es into some functions and remove some _locked
  variants down to where the lists are actually accessed to
  make things simpler. (Linus)
- Drop *all* mutexes completely from pinctrl_lookup_state()
  and pinctrl_select_state() - no relevant mutex was taken
  and it was unclear what this was protecting against. (Linus)

Reported by : Seraphin Bonnaffe 
Signed-off-by: Patrice Chotard 
Signed-off-by: Linus Walleij

pinmux: forbid mux_usecount to be set at UINT_MAX

2013-03-21T18:26:18+00:00

If pin_free is called on a pin already freed, mux_usecount is set to
UINT_MAX which is really a bad idea.

This will issue a warning, so that we can correct the code responsible
for the double free.

Signed-off-by: Richard Genoud 
Reviewed-by: Stephen Warren 
Signed-off-by: Linus Walleij

pinctrl: pinmux: Release all taken pins in pinmux_enable_setting error paths

2012-11-11T19:18:32+00:00

Currently pinmux_enable_setting does not release all taken pins if
ops->enable() returns error. This patch ensures all taken pins are
released in any error paths.

Signed-off-by: Axel Lin 
Signed-off-by: Linus Walleij

pinctrl: reserve pins when states are activated

2012-11-11T18:05:56+00:00

This switches the way that pins are reserved for multiplexing:

We used to do this when the map was parsed, at the creation of
the settings inside the pinctrl handle, in pinmux_map_to_setting().

However this does not work for us, because we want to use the
same set of pins with different devices at different times: the
current code assumes that the pin groups in a pinmux state will
only be used with one single device, albeit different groups can
be active at different times. For example if a single I2C driver
block is used to drive two different busses located on two
pin groups A and B, then the pins for all possible states of a
function are reserved when fetching the pinctrl handle: the
I2C bus can choose either set A or set B by a mux state at
runtime, but all pins in both group A and B (the superset) are
effectively reserved for that I2C function and mapped to the
device. Another device can never get in and use the pins in
group A, even if the device/function is using group B at the
moment.

Instead: let use reserve the pins when the state is activated
and drop them when the state is disabled, i.e. when we move to
another state. This way different devices/functions can use the
same pins at different times.

We know that this is an odd way of doing things, but we really
need to switch e.g. an SD-card slot to become a tracing output
sink at runtime: we plug in a special "tracing card" then mux
the pins that used to be an SD slot around to the tracing
unit and push out tracing data there instead of SD-card
traffic.

As a side effect pinmux_free_setting() is unused but the stubs
are kept for future additions of code.

Cc: Patrice Chotard 
Cc: Loic Pallardy 
Acked-by: Stephen Warren 
Tested-by: Jean Nicolas Graux 
Signed-off-by: Linus Walleij

pinctrl: use kasprintf() in pinmux_request_gpio()

2012-09-14T13:53:13+00:00

Instead of using a temporary buffer, snprintf() and kstrdup(), just
use kasprintf() that does the same thing in just oneline.

Signed-off-by: Thomas Petazzoni 
Acked-by: Stephen Warren 
Acked-by: Colin Cross 
Signed-off-by: Linus Walleij

pinctrl: make pinmux disable function optional

2012-05-15T07:44:50+00:00

Some SoCs may not have pinmux disable function in HW.

Acked-by: Stephen Warren 
Signed-off-by: Dong Aisheng 
Signed-off-by: Linus Walleij

pinctrl: add more info to error msgs in pin_request

2012-05-07T12:44:38+00:00

Additionally print which pin the request failed for, which entity already
claimed it, and what entity was trying to claim it.

Remove duplicate device name from a debug message.

Clean up some indentation.

Signed-off-by: Stephen Warren 
Signed-off-by: Linus Walleij

pinctrl: enhance reporting of errors when loading from DT

2012-04-26T21:11:04+00:00

There are a few places in the api where the code simply returns -EINVAL when
it finds an error. An example is pinmux_map_to_setting() which now reports an
error if we try to match a group with a function that it does not support.

The reporting of errors in pinconf_check_ops and pinmux_check_ops now has the
same style and is located inside the according functions and not the calling
code.

When the map is found in the DT but the default state can not be selected we
get an error to know that the code at least tried.

The patch also removes a stray word from one comment and a "->" from another
for the sake of consistency.

Finally we replace a few pr_err/debug() calls with dev_err/dbg().

Thanks go to Stephen Warren for reviewing the patch and enhancing the reporting
inside pinmux_map_to_setting().

Signed-off-by: John Crispin 
Acked-by: Stephen Warren 
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Linus Walleij

pinctrl: fix signed vs unsigned conditionals inside pinmux_map_to_setting

2012-04-24T13:09:50+00:00

pinmux_map_to_setting() uses setting->data.mux.func/group to store the return
code of pinmux_func_name_to_selector/pinctrl_get_group_selector(). However,
struct pinctrl_setting_mux defines these elements as unsigned, resulting in all
error codes getting lost. The conditionals following the assignments will always
evaluate to false thus breaking the error paths.

This bug can be triggered by loading a pinmux group map from the devicetree
with an invalid function/group string.

Signed-off-by: John Crispin 
Acked-by: Stephen Warren 
Acked-by: Dong Aisheng 
Signed-off-by: Linus Walleij

pinctrl: show pin name when request pins

2012-04-18T11:53:13+00:00

Pin name is more useful to users.

Acked-by: Stephen Warren 
Signed-off-by: Dong Aisheng 
Signed-off-by: Linus Walleij