Commit Graph

86 Commits

Author SHA1 Message Date
Bartosz Golaszewski
76aa3de709 eeprom: at24: fix retrieving the at24_chip_data structure
Commit feb2f19b1e ("eeprom: at24: move platform data processing into
a separate routine") introduced a bug where we incorrectly retireve the
at24_chip_data structure. Remove the unnecessary ampersand operator.

Fixes: feb2f19b1e ("eeprom: at24: move platform data processing into a separate routine")
Reported-by: Vadim Pasternak <vadimp@mellanox.com>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
2018-05-09 17:16:06 +02:00
Bartosz Golaszewski
4ac0d3fb13 eeprom: at24: use SPDX identifier instead of GPL boiler-plate
Replace the GPL (or later) header with the SPDX identifier
for GPL-2.0+.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Tested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-03-23 17:53:06 +01:00
Bartosz Golaszewski
34d43faf3a eeprom: at24: simplify the i2c functionality checking
Save one call and make code prettier by checking the i2c functionality
in the beginning of at24_probe(), saving the relevant values and
reusing them later.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Tested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-03-23 16:25:45 +01:00
Bartosz Golaszewski
df3da615e3 eeprom: at24: fix a line break
Align the broken line with the opening parenthesis to stay consistent
with the rest of the driver code.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Tested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-03-23 16:25:45 +01:00
Bartosz Golaszewski
de5db101fc eeprom: at24: tweak newlines
Remove the newline between the nvmem registration and its return value
check. This is consistent with the rest of the driver code.

Add a missing newline between two pdata checks to stay consistent with
all the others.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Tested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-03-23 16:25:45 +01:00
Bartosz Golaszewski
551a12669d eeprom: at24: refactor at24_probe()
The code in at24_probe() is pretty mangled. It can be cleaned up a bit
by doing things one by one.

Let's group the code by logic: parse and verify pdata, initialize the
regmap, allocate and fill the fields of at24_data, allocate dummy i2c
devices, initialize pm & register with nvmem.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Tested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-03-23 16:25:44 +01:00
Bartosz Golaszewski
7c2806642e eeprom: at24: remove at24_platform_data from at24_data
Not all fields from at24_platform_data are needed in at24_data. Let's
keep just the ones we need and not carry the whole platform_data
structure all the time.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Tested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-03-23 16:25:00 +01:00
Bartosz Golaszewski
feb2f19b1e eeprom: at24: move platform data processing into a separate routine
This driver can receive its device data from different sources
depending on the system. Move the entire code processing platform data,
device tree and acpi into a separate function.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Tested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-03-23 16:25:00 +01:00
Bartosz Golaszewski
48b6a7d1ee eeprom: at24: switch to using probe_new() from the i2c framework
Use the new probe() style for i2c drivers.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Tested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-03-23 16:25:00 +01:00
Bartosz Golaszewski
f1a640c5dc eeprom: at24: provide and use at24_base_client_dev()
Use a helper function for accessing the device struct of the base
i2c client. This routine is named in a way that reflects its purpose
unlike the previously hand-coded dereferencing.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Tested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-03-23 16:25:00 +01:00
Bartosz Golaszewski
11288b7c70 eeprom: at24: readability tweak in at24_probe()
Use a helper variable for the size we want to allocate with
devm_kzalloc() and save an ugly line break.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Tested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-03-23 16:25:00 +01:00
Bartosz Golaszewski
021c7d7b67 eeprom: at24: use a helper variable for dev
We use the &client->dev construct all over in at24_probe(). Use
a helper variable which is more readable and allows to avoid a couple
unnecessary line breaks.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Tested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-03-23 16:25:00 +01:00
Bartosz Golaszewski
f2adff6660 eeprom: at24: rename chip to pdata in at24_probe()
Reflect the purpose of this variable: it contains platform data so name
it such.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Tested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-03-23 16:25:00 +01:00
Bartosz Golaszewski
1f77d1859c eeprom: at24: rename at24_get_pdata()
As preparation for at24_probe() refactoring: rename at24_get_pdata()
to at24_properties_to_pdata(). We're doing it because we'll move the
pdata parsing code into a separate function which will be called
at24_get_pdata(). Current routine with that name actually parses
the device properties so change its name to reflect its purpose.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Tested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-03-23 16:25:00 +01:00
Bartosz Golaszewski
7c7f428eda eeprom: at24: don't check if byte_len is a power of 2
We support certain models the size of which is not a power of 2. This
is not a reason to emit a warning.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Tested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-03-23 16:25:00 +01:00
Bartosz Golaszewski
53998fa89a eeprom: at24: make struct initialization uniform in at24_probe()
When zeroing structs, use "{ }" everywhere.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Tested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-03-23 16:25:00 +01:00
Bartosz Golaszewski
c4fee330f9 eeprom: at24: drop redundant variable in at24_write()
We can reuse ret instead of defining a loop-local status variable.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Tested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-03-23 16:25:00 +01:00
Bartosz Golaszewski
eb27fde273 eeprom: at24: drop redundant variable in at24_read()
We can reuse ret instead of defining a loop-local status variable.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Tested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-03-23 16:25:00 +01:00
Bartosz Golaszewski
14263b893a eeprom: at24: remove code separators
These are just two left-overs from times when this driver was bigger.

They are not really useful anymore. Remove them.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Tested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-03-23 16:24:59 +01:00
Bartosz Golaszewski
5ca2b5b70e eeprom: at24: arrange local variables
Arrange declarations of local variables by line length as visually
it's easier to read.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Tested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-03-23 16:22:30 +01:00
Bartosz Golaszewski
8cdc4e7e6d eeprom: at24: remove nvmem_config from at24_data
This structure only needs to exist during the call to nvmem_register().

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Tested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-03-23 16:22:30 +01:00
Bartosz Golaszewski
d154316dde eeprom: at24: disable regmap locking
We use our own mutex for locking. Disable the regmap-specific locking.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Tested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-03-23 16:22:30 +01:00
Bartosz Golaszewski
0f30aca72c eeprom: at24: extend the list of chips supported in DT
Add all supported at24 variants to the of_match table.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
2018-01-02 17:52:45 +01:00
Bartosz Golaszewski
6ce261e87f eeprom: at24: add support for the write-protect pin
AT24 EEPROMs have a write-protect pin, which - when pulled high -
inhibits writes to the upper quadrant of memory (although it has been
observed that on some chips it disables writing to the entire memory
range).

On some boards, this pin is connected to a GPIO and pulled high by
default, which forces the user to manually change its state before
writing. On linux this means that we either need to hog the line all
the time, or set the GPIO value before writing from outside of the
at24 driver.

Make the driver check if the write-protect GPIO was defined in the
device tree and pull it low whenever writing to the EEPROM.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
2018-01-01 19:40:50 +01:00
Sven Van Asbroeck
ef542e59d7 eeprom: at24: remove temporary fix for at24mac402 size
The chip size passed via devicetree, i2c, or acpi device ids is now no
longer limited to a power of two. So the temporary fix can be removed.

Signed-off-by: Sven Van Asbroeck <svendev@arcx.com>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
2018-01-01 19:40:49 +01:00
Sven Van Asbroeck
b680f4fa74 eeprom: at24: convert magic numbers to structs
Fundamental properties such as capacity and page size differ among
at24-type chips. But these chips do not have an id register, so this
can't be discovered at runtime.

Traditionally, at24-type eeprom properties were determined in two ways:
- by passing a 'struct at24_platform_data' via platform_data, or
- by naming the chip type in the devicetree, which passes a 'magic
  number' to probe(), which is then converted to a 'struct
  at24_platform_data'.

Recently a bug was discovered because the magic number rounds down all
chip sizes to the lowest power of two. This was addressed by
a work-around commit 5478e478ee ("eeprom: at24: correctly set the
size for at24mac402"), with the wish that magic numbers should over
time be converted to structs.

This patch replaces the magic numbers with 'struct at24_chip_data'.

Signed-off-by: Sven Van Asbroeck <svendev@arcx.com>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
2018-01-01 19:40:49 +01:00
Bartosz Golaszewski
eef6939849 eeprom: at24: code shrink
A regmap_config struct is pretty big and declaring two of them
statically just to tweak the reg_bits value adds unnecessary bloat.

Declare the regmap config locally in at24_probe() instead.

Bloat-o-meter output for ARM:

add/remove: 0/2 grow/shrink: 1/0 up/down: 4/-272 (-268)
Function                                     old     new   delta
at24_probe                                  1560    1564      +4
regmap_config_8                              136       -    -136
regmap_config_16                             136       -    -136
Total: Before=7012, After=6744, chg -3.82%

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
2018-01-01 19:40:49 +01:00
Bartosz Golaszewski
ec3c2d518b eeprom: at24: use a common prefix for all symbols in at24.c
There are a couple symbols defined in the driver source file which are
missing the at24_ prefix. This patch fixes that.

For module params: use module_param_named() in order to not break
userspace.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
2018-01-01 19:40:49 +01:00
Bartosz Golaszewski
aa4ce22897 eeprom: at24: fix coding style issues
Fix issues reported by checkpatch for at24.c.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
2018-01-01 19:40:48 +01:00
Sven Van Asbroeck
e32213fbc5 eeprom: at24: support eeproms that do not auto-rollover reads
Some multi-address eeproms in the at24 family may not automatically
roll-over reads to the next slave address. On those eeproms, reads
that straddle slave boundaries will not work correctly.

Solution:
Mark such eeproms with a flag that prevents reads straddling
slave boundaries. Add the AT24_FLAG_NO_RDROL flag to the eeprom
entry in the device_id table, or add 'no-read-rollover' to the
eeprom devicetree entry.

Note that I have not personally enountered an at24 chip that
does not support read rollovers. They may or may not exist.
However, my hardware requires this functionality because of
a quirk.

Signed-off-by: Sven Van Asbroeck <svendev@arcx.com>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
2018-01-01 19:40:48 +01:00
Heiner Kallweit
a23727cb68 eeprom: at24: remove now unneeded smbus-related code
Remove remaining now unneeded code dealing with SMBUS details.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
2018-01-01 19:40:47 +01:00
Heiner Kallweit
dd69a9da71 eeprom: at24: remove old read functions
Remove the old and now unused read functions.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
2018-01-01 19:40:47 +01:00
Heiner Kallweit
4bb5c13cc2 eeprom: at24: add regmap-based read function
Add regmap-based read function and instead of using three different
read functions (standard, mac, serial) use just one and factor out the
read offset adjustment for mac and serial to at24_adjust_read_offset.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
2018-01-01 19:40:46 +01:00
Heiner Kallweit
d4297d6795 eeprom: at24: remove old write functions
Remove the old and now unused write functions.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
2018-01-01 19:40:46 +01:00
Heiner Kallweit
8e5888e17f eeprom: at24: add regmap-based write function
Add a regmap-based write function.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
2018-01-01 19:40:46 +01:00
Heiner Kallweit
4604948641 eeprom: at24: change at24_translate_offset return type
Change return type of at24_translate_offset to *at24_client to make
member regmap accessible for subsequent patches of this series.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
2018-01-01 19:40:46 +01:00
Heiner Kallweit
5c01525847 eeprom: at24: add basic regmap_i2c support
This patch adds basic regmap support to be used by subsequent
patches of this series.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
2018-01-01 19:40:46 +01:00
David Lechner
7f6d2ecd3d eeprom: at24: change nvmem stride to 1
Trying to read the MAC address from an eeprom that has an offset that
is not a multiple of 4 causes an error currently.

Fix it by changing the nvmem stride to 1.

Cc: stable@vger.kernel.org
Signed-off-by: David Lechner <david@lechnology.com>
[Bartosz: tweaked the commit message]
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
2017-12-06 11:22:04 +01:00
Sakari Ailus
f9ecc83f8d eeprom: at24: fix I2C device selection for runtime PM
The at24 driver creates dummy I2C devices to access offsets in the chip
that are outside the area supported using a single I2C address. It is not
meaningful to use runtime PM to such devices; the system firmware (ACPI)
does not know about these devices nor runtime PM was enabled for them.
Always use the real device instead of the dummy ones.

Fixes: 98e8201039 ("eeprom: at24: enable runtime pm support")
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Tested-by: Sven Van Asbroeck on a 24AA16/24LC16B <svendev@arcx.com>
[Bartosz: rebased on top of previous fixes for 4.15, tweaked the
          commit message]
[Sven: fixed Bartosz's rebase]
Signed-off-by: Sven Van Asbroeck <svendev@arcx.com>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
2017-12-03 20:50:31 +01:00
Heiner Kallweit
d9bcd462da eeprom: at24: check at24_read/write arguments
So far we completely rely on the caller to provide valid arguments.
To be on the safe side perform an own sanity check.

Cc: stable@vger.kernel.org
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
2017-11-29 16:05:37 +01:00
Heiner Kallweit
644a1f19c6 eeprom: at24: fix reading from 24MAC402/24MAC602
Chip datasheet mentions that word addresses other than the actual
start position of the MAC delivers undefined results. So fix this.
Current implementation doesn't work due to this wrong offset.

Cc: stable@vger.kernel.org
Fixes: 0b813658c1 ("eeprom: at24: add support for at24mac series")
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
2017-11-29 16:05:30 +01:00
Bartosz Golaszewski
5478e478ee eeprom: at24: correctly set the size for at24mac402
There's an ilog2() expansion in AT24_DEVICE_MAGIC() which rounds down
the actual size of EUI-48 byte array in at24mac402 eeproms to 4 from 6,
making it impossible to read it all.

Fix it by manually adjusting the value in probe().

This patch contains a temporary fix that is suitable for stable
branches. Eventually we'll probably remove the call to ilog2() while
converting the magic values to actual structs.

Cc: stable@vger.kernel.org
Fixes: 0b813658c1 ("eeprom: at24: add support for at24mac series")
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
2017-11-29 15:22:24 +01:00
Javier Martinez Canillas
7f2a2f0d0d eeprom: at24: Add OF device ID table
The driver doesn't have a struct of_device_id table but supported devices
are registered via Device Trees. This is working on the assumption that a
I2C device registered via OF will always match a legacy I2C device ID and
that the MODALIAS reported will always be of the form i2c:<device>.

But this could change in the future so the correct approach is to have an
OF device ID table if the devices are registered via OF.

To maintain backward compatibility with old Device Trees, only use the OF
device ID table .data if the device was registered via OF and the OF node
compatible matches an entry in the OF device ID table.

Suggested-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
2017-11-05 22:21:28 +01:00
Divagar Mohandass
98e8201039 eeprom: at24: enable runtime pm support
Currently the device is kept in D0, there is an opportunity
to save power by enabling runtime pm.

Device can be daisy chained from PMIC and we can't rely on I2C core
for auto resume/suspend. Driver will decide when to resume/suspend.

Reviewed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Divagar Mohandass <divagar.mohandass@intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
2017-10-17 23:33:03 +02:00
Divagar Mohandass
dbc1ab9c12 eeprom: at24: add support to fetch eeprom device property "size"
Obtain the size of the EEPROM chip from DT if the "size" property is
specified for the device.

Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Divagar Mohandass <divagar.mohandass@intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
2017-10-17 23:32:04 +02:00
Ben Gardner
dd905a61e9 misc: eeprom: at24: use device_property_*() functions instead of of_get_property()
Allow the at24 driver to get configuration information from both OF and
ACPI by using the more generic device_property functions.
This change was inspired by the at25.c driver.

I have a custom board with a ST M24C02 EEPROM attached to an I2C bus.
With the following ACPI construct, this patch instantiates a working
instance of the driver.

Device (EEP0) {
 Name (_HID, "PRP0001")
 Name (_DSD, Package () {
  ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
  Package () {
   Package () {"compatible", Package () {"st,24c02"}},
   Package () {"pagesize", 16},
  },
 })
 Name (_CRS, ResourceTemplate () {
  I2cSerialBus (
   0x0057, ControllerInitiated, 400000,
   AddressingMode7Bit, "\\_SB.PCI0.I2C3", 0x00,
   ResourceConsumer,,)
 })
}

Signed-off-by: Ben Gardner <gardner.ben@gmail.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
2017-02-11 21:23:43 +01:00
Bartosz Golaszewski
00f0ea70d2 eeprom: at24: check if the chip is functional in probe()
The at24 driver doesn't check if the chip is functional in its probe
function. This leads to instantiating devices that are not physically
present. For example the cape EEPROMs for BeagleBone Black are defined
in the device tree at four addresses on i2c2, but normally only one of
them is present.

If the userspace doesn't know the location in advance, it will need to
check if reading the nvmem attributes fails to determine which EEPROM
is actually there.

Try to read a single byte in probe() and bail-out with -ENODEV if the
read fails.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
2016-08-22 08:19:58 +02:00
Bartosz Golaszewski
24da3cc0e2 eeprom: at24: tweak the loop_until_timeout() macro
loop_until_timeout() replaced a do {} while loop in the at24 driver
with a for loop which, under certain circumstances (such as heavy load
or low value of the write_timeout argument), can lead to the code in
the loop never being executed.

Make sure that at least one iteration of the code enclosed within
loop_until_timeout() is always executed.

Suggested-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
2016-07-18 20:07:54 +02:00
Bartosz Golaszewski
0b813658c1 eeprom: at24: add support for at24mac series
Add a new read function to the at24 driver allowing to retrieve the
factory-programmed mac address embedded in chips from the at24mac
family.

These chips can be instantiated similarily to the at24cs family,
except that there's no way of having access to both the serial number
and the mac address at the same time - the user must instantiate
either an at24cs or at24mac device as both special memory areas are
accessible on the same slave address.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
2016-07-17 19:58:00 +02:00
Bartosz Golaszewski
818d0220d8 eeprom: at24: support reading the serial number for 24csxx
The chips from the at24cs family have two memory areas - a regular
read-write block and a read-only area containing the serial number.

The latter is visible on a different slave address (the address of the
rw memory block + 0x08). In order to access both blocks the user needs
to instantiate a regular at24c device for the rw block address and a
corresponding at24cs device on the serial number block address.

Add a function that allows to access the serial number and assign it
to at24->read_func if the chip allows serial number read operations
and the driver was passed the relevant flag for this device.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
2016-07-17 19:57:30 +02:00