"Slow" GPIOs (usually those connected over an SPI or an I2C bus) are,
well, slow in their operation. It is generally a good idea to avoid
using them for time-critical operation, but sometimes the hardware just
sucks, and the software has to cope. In addition to that, the I2C bus
itself does not actually define any strict timing limits; the bus is
free to go all the way down to DC. The timeouts (and therefore the
slowest acceptable frequency) are present only in SMBus.
The `can_sleep` is IMHO a wrong concept to use here. My SPI-to-quad-UART
chip (MAX14830) is connected via a 26MHz SPI bus, and it happily drives
SCL at 200kHz (5µs pulses) during my benchmarks. That's faster than the
maximal allowed speed of the traditional I2C.
The previous version of this code did not really block operation over
slow GPIO pins, anyway. Instead, it just resorted to printing a warning
with a backtrace each time a GPIO pin was accessed, thereby slowing
things down even more.
Finally, it's not just me. A similar patch was originally submitted in
2015 [1].
[1] https://patchwork.ozlabs.org/patch/450956/
Signed-off-by: Jan Kundrát <jan.kundrat@cesnet.cz>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Add fault injection capabilities to the i2c-gpio driver. When connected
to another I2C bus, it can create unusual states which the other I2C bus
master driver needs to handle. Only for debugging!
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
This adds support for using the "sda" and "scl" GPIOs in
device tree instead of anonymously using index 0 and 1 of
the "gpios" property.
We add a helper function to retrieve the GPIO descriptors
and some explicit error handling since the probe may have
to be deferred. At least this happened to me when moving
to using named "sda" and "scl" lines (all of a sudden this
started to probe before the GPIO driver) so we need to
gracefully defer probe when we ge -ENOENT in the error
pointer.
Suggested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
By creating local variables for *dev and *np, the code become
much easier to read, in my opinion.
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
The I2C GPIO bitbang driver currently emulates open drain
behaviour by implementing what the gpiolib already does:
not actively driving the line high, instead setting it to
input.
This makes no sense. Use the new facility in gpiolib to
request the lines enforced into open drain mode, and let
the open drain emulation already present in the gpiolib
kick in and handle this.
As a bonus: if the GPIO driver in the back-end actually
supports open drain in hardware using the .set_config()
callback, it will be utilized. That's correct: we never
used that hardware feature before, instead relying on
emulating open drain even if the GPIO controller could
actually handle this for us.
Users will sometimes get messages like this:
gpio-485 (?): enforced open drain please flag it properly
in DT/ACPI DSDT/board file
gpio-486 (?): enforced open drain please flag it properly
in DT/ACPI DSDT/board file
i2c-gpio gpio-i2c: using lines 485 (SDA) and 486 (SCL)
Which is completely proper: since the line is used as
open drain, it should actually be flagged properly with
e.g.
gpios = <&gpio0 5 (GPIO_ACTIVE_HIGH|GPIO_OPEN_DRAIN)>,
<&gpio0 6 (GPIO_ACTIVE_HIGH|GPIO_OPEN_DRAIN)>;
Or similar facilities in board file descriptor tables
or ACPI DSDT.
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
This converts the GPIO-based I2C-driver to using GPIO
descriptors instead of the old global numberspace-based
GPIO interface. We:
- Convert the driver to unconditionally grab two GPIOs
from the device by index 0 (SDA) and 1 (SCL) which
will work fine with device tree and descriptor tables.
The existing device trees will continue to work just
like before, but without any roundtrip through the
global numberspace.
- Brutally convert all boardfiles still passing global
GPIOs by registering descriptor tables associated with
the devices instead so this driver does not need to keep
supporting passing any GPIO numbers as platform data.
There is no stepwise approach as elegant as this, I
strongly prefer this big hammer over any antsteps for this
conversion. This way the old GPIO numbers go away and
NEVER COME BACK.
Special conversion for the different boards utilizing
I2C-GPIO:
- EP93xx (arch/arm/mach-ep93xx): pretty straight forward as
all boards were using the same two GPIO lines, just define
these two in a lookup table for "i2c-gpio" and register
these along with the device. None of them define any
other platform data so just pass NULL as platform data.
This platform selects GPIOLIB so all should be smooth.
The pins appear on a gpiochip for bank "G" as pins 1 (SDA)
and 0 (SCL).
- IXP4 (arch/arm/mach-ixp4): descriptor tables have to
be registered for each board separately. They all use
"IXP4XX_GPIO_CHIP" so it is pretty straight forward.
Most board define no other platform data than SCL/SDA
so they can drop the #include of <linux/i2c-gpio.h> and
assign NULL to platform data.
The "goramo_mlr" (Goramo Multilink Router) board is a bit
worrisome: it implements its own I2C bit-banging in the
board file, and optionally registers an I2C serial port,
but claims the same GPIO lines for itself in the board file.
This is not going to work: there will be competition for the
GPIO lines, so delete the optional extra I2C bus instead, no
I2C devices are registered on it anyway, there are just hints
that it may contain an EEPROM that may be accessed from
userspace. This needs to be fixed up properly by the serial
clock using I2C emulation so drop a note in the code.
- KS8695 board acs5k (arch/arm/mach-ks8695/board-acs5.c)
has some platform data in addition to the pins so it needs to
be kept around sans GPIO lines. Its GPIO chip is named
"KS8695" and the arch selects GPIOLIB.
- PXA boards (arch/arm/mach-pxa/*) use some of the platform
data so it needs to be preserved here. The viper board even
registers two GPIO I2Cs. The gpiochip is named "gpio-pxa" and
the arch selects GPIOLIB.
- SA1100 Simpad (arch/arm/mach-sa1100/simpad.c) defines a GPIO
I2C bus, and the arch selects GPIOLIB.
- Blackfin boards (arch/blackfin/bf533 etc) for these I assume
their I2C GPIOs refer to the local gpiochip defined in
arch/blackfin/kernel/bfin_gpio.c names "BFIN-GPIO".
The arch selects GPIOLIB. The boards get spiked with
IF_ENABLED(I2C_GPIO) but that is a side effect of it
being like that already (I would just have Kconfig select
I2C_GPIO and get rid of them all.) I also delete any
platform data set to 0 as it will get that value anyway
from static declartions of platform data.
- The MIPS selects GPIOLIB and the Alchemy machine is using
two local GPIO chips, one of them has a GPIO I2C. We need
to adjust the local offset from the global number space here.
The ATH79 has a proper GPIO driver in drivers/gpio/gpio-ath79.c
and AFAICT the chip is named "ath79-gpio" and the PB44
PCF857x expander spawns from this on GPIO 1 and 0. The latter
board only use the platform data to specify pins so it can be
cut altogether after this.
- The MFD Silicon Motion SM501 is a special case. It dynamically
spawns an I2C bus off the MFD using sm501_create_subdev().
We use an approach to dynamically create a machine descriptor
table and attach this to the "SM501-LOW" or "SM501-HIGH"
gpiochip. We use chip-local offsets to grab the right lines.
We can get rid of two local static inline helpers as part
of this refactoring.
Cc: Steven Miao <realmz6@gmail.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Magnus Damm <magnus.damm@gmail.com>
Cc: Ben Dooks <ben.dooks@codethink.co.uk>
Cc: Heiko Schocher <hs@denx.de>
Acked-by: Wu, Aaron <Aaron.Wu@analog.com>
Acked-by: Olof Johansson <olof@lixom.net>
Acked-by: Lee Jones <lee.jones@linaro.org>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Now that we have a custom printf format specifier, convert users of
full_name to use %pOF instead. This is preparation to remove storing
of the full path string for each node.
Signed-off-by: Rob Herring <robh@kernel.org>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Commit a0682a31 ("i2c: gpio: Use devm_gpio_request()") left unused
code behind, clean it up.
Fixes: a0682a3158 ("i2c: gpio: Use devm_gpio_request()")
Signed-off-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Use devm_gpio_request() to make cleanup paths simpler.
Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Reviewed-by: Violeta Menendez <violeta.menendez@codethink.co.uk>
Reviewed-by: Ian Molton <ian.molton@codethink.co.uk>
Tested-by: Violeta Menendez <violeta.menendez@codethink.co.uk>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
When using device-tree and the i2c-gpio driver is called before the
GPIO node has been probed then it needs to correctly defer the probe
instead of returning a permanent error that the gpio numbers are not
valid.
This fixes the following error:
/i2c@2: invalid GPIO pins, sda=-517/scl=-517
Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
'of_match_ptr' is defined in linux/of.h. Include it explicitly to
avoid build breakage in the future.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
I2C of helpers used to live in of_i2c.c but experience (from SPI) shows
that it is much cleaner to have this in the core. This also removes a
circular dependency between the helpers and the core, and so we can
finally register child nodes in the core instead of doing this manually
in each driver. So, fix the drivers and documentation, too.
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Use the wrapper function for retrieving the platform data instead of
accessing dev->platform_data directly.
Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
GPIOs may not be available immediately when i2c-gpio looks for them.
Implement support for deferred probing so that probing can be
attempted again later when GPIO pins are finally available.
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Tested-by: Bo Shen <voice.shen@atmel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
CONFIG_HOTPLUG is going away as an option. As result the __dev*
markings will be going away.
Remove use of __devinit, __devexit_p, __devinitdata, __devinitconst,
and __devexit.
Signed-off-by: Bill Pemberton <wfp5p@virginia.edu>
Acked-by: Peter Korsgaard <peter.korsgaard@barco.com> (for ocores and mux-gpio)
Acked-by: Havard Skinnemoen <hskinnemoen@gmail.com> (for i2c-gpio)
Acked-by: Guan Xuetao <gxt@mprc.pku.edu.cn> (for puf3)
Acked-by: Barry Song <baohua.song@csr.com> (for sirf)
Reviewed-by: Jean Delvare <khali@linux-fr.org>
[wsa: Fixed "foo* bar" flaws while we are here]
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
When having multiple i2c-gpio nodes, the name for each is same.
So add the patch to fix it.
The adap->name printing information was added by myself
without this patch the log information is as following
---<8---
adap->name = i2c-gpio-1
i2c-gpio i2c.2: using pins 30 (SDA) and 31 (SCL)
adap->name = i2c-gpio-1
i2c-gpio i2c.3: using pins 64 (SDA) and 65 (SCL)
--->8---
with this patch, the log information is as following
---<8---
adap->name = i2c.2
i2c-gpio i2c.2: using pins 30 (SDA) and 31 (SCL)
adap->name = i2c.3
i2c-gpio i2c.3: using pins 64 (SDA) and 65 (SCL)
--->8---
Signed-off-by: Bo Shen <voice.shen@atmel.com>
Reviewed-by: Stephen Warren <swarren@nvidia.com>
[wsa: minor fixes to the commit mesage]
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Commit 488bf314b ("i2c: Allow i2c_add_numbered_adapter() to assign a
bus id") reworked i2c_add_numbered_adapter() to call i2c_add_adapter()
if requested bus was -1.
This allows to simplify driver's initialization procedure by using
just one function for static and dynamic adapter id registration.
This patch updates few more drivers (missed out in original patch)
to use this functionality.
Signed-off-by: Karol Lewandowski <k.lewandowsk@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
To achieve DT support, we need to populate a custom platform_data in a
private struct from DT information. To simplify code, the adapter and
algorithm are also put into the private struct.
Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Rob Herring <rob.herring@calxeda.com>
Acked-by: Wolfram Sang <w.sang@pengutronix.de>
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
GPIO driven I2C bus can be used for controlling the PMIC chip. The
example of such configuration is Samsung Aquila board.
This patch moves initialization code to subsys_initcall() to ensure
that the i2c bus is available early so the regulators can be quickly
probed and available for other devices on their probe() call.
Such solution has been proposed by Mark Brown to fix the problem of
the regulators not beeing available on the peripheral device probe():
http://lists.infradead.org/pipermail/linux-arm-kernel/2010-March/011971.html
Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
Reviewed-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files. percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.
percpu.h -> slab.h dependency is about to be removed. Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability. As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.
http://userweb.kernel.org/~tj/misc/slabh-sweep.py
The script does the followings.
* Scan files for gfp and slab usages and update includes such that
only the necessary includes are there. ie. if only gfp is used,
gfp.h, if slab is used, slab.h.
* When the script inserts a new include, it looks at the include
blocks and try to put the new include such that its order conforms
to its surrounding. It's put in the include block which contains
core kernel includes, in the same order that the rest are ordered -
alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
doesn't seem to be any matching order.
* If the script can't find a place to put a new include (mostly
because the file doesn't have fitting include block), it prints out
an error message indicating which .h file needs to be added to the
file.
The conversion was done in the following steps.
1. The initial automatic conversion of all .c files updated slightly
over 4000 files, deleting around 700 includes and adding ~480 gfp.h
and ~3000 slab.h inclusions. The script emitted errors for ~400
files.
2. Each error was manually checked. Some didn't need the inclusion,
some needed manual addition while adding it to implementation .h or
embedding .c file was more appropriate for others. This step added
inclusions to around 150 files.
3. The script was run again and the output was compared to the edits
from #2 to make sure no file was left behind.
4. Several build tests were done and a couple of problems were fixed.
e.g. lib/decompress_*.c used malloc/free() wrappers around slab
APIs requiring slab.h to be added manually.
5. The script was run on all .h files but without automatically
editing them as sprinkling gfp.h and slab.h inclusions around .h
files could easily lead to inclusion dependency hell. Most gfp.h
inclusion directives were ignored as stuff from gfp.h was usually
wildly available and often used in preprocessor macros. Each
slab.h inclusion directive was examined and added manually as
necessary.
6. percpu.h was updated not to include slab.h.
7. Build test were done on the following configurations and failures
were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my
distributed build env didn't work with gcov compiles) and a few
more options had to be turned off depending on archs to make things
build (like ipr on powerpc/64 which failed due to missing writeq).
* x86 and x86_64 UP and SMP allmodconfig and a custom test config.
* powerpc and powerpc64 SMP allmodconfig
* sparc and sparc64 SMP allmodconfig
* ia64 SMP allmodconfig
* s390 SMP allmodconfig
* alpha SMP allmodconfig
* um on x86_64 SMP allmodconfig
8. percpu.h modifications were reverted so that it could be applied as
a separate patch and serve as bisection point.
Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.
Signed-off-by: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Change the i2c_gpio driver to use platform_driver_register()
instead of platform_driver_probe() to ensure that is can
attach to any devices that may be loaded after it has initialised.
Acked-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Let general purpose I2C/SMBus bus drivers add SPD to their class. Once
this is done, we will be able to tell the eeprom driver to only probe
for SPD EEPROMs and similar on these buses.
Note that I took a conservative approach here, adding I2C_CLASS_SPD to
many drivers that have no idea whether they can host SPD EEPROMs or not.
This is to make sure that the eeprom driver doesn't stop probing buses
where SPD EEPROMs or equivalent live.
So, bus driver maintainers and users should feel free to remove the SPD
class from drivers those buses never have SPD EEPROMs or they don't
want the eeprom driver to bind to them. Likewise, feel free to add the
SPD class to any bus driver I might have missed.
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Since 43cc71eed1, the platform
modalias is prefixed with "platform:". Add MODULE_ALIAS() to the
hotpluggable I2C platform drivers, to allow module auto loading.
[ db: add some more drivers ]
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
This is required to let hwmon drivers attach to the adapter.
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
It turns out that platform_device.id is a "u32" so testing it for being
nonnegative is useless when setting up an i2c bitbang device. Instead,
do what the platform_bus code does and test it against the value "-1".
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Acked-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
i2c_gpio_getsda() and i2c_gpio_getscl() are only used in this file.
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Acked-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Use i2c_bit_add_numbered_bus() so that the i2c-gpio adapter works well
with new-style pre-declared devices.
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
This is a very simple bitbanging I2C bus driver utilizing the new
arch-neutral GPIO API. Useful for chips that don't have a built-in
I2C controller, additional I2C busses, or testing purposes.
To use, include something similar to the following in the
board-specific setup code:
#include <linux/i2c-gpio.h>
static struct i2c_gpio_platform_data i2c_gpio_data = {
.sda_pin = GPIO_PIN_FOO,
.scl_pin = GPIO_PIN_BAR,
};
static struct platform_device i2c_gpio_device = {
.name = "i2c-gpio",
.id = 0,
.dev = {
.platform_data = &i2c_gpio_data,
},
};
Register this platform_device, set up the I2C pins as GPIO if
required and you're ready to go. This will use default values for
udelay and timeout, and will work with GPIO hardware that does not
support open drain mode, but allows sensing of the SDA and SCL lines
even when they are being driven.
Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
