user/sven/linux.git/include/linux/i2c.h, branch v4.8.16

Revert "i2c: core: Add function for finding the bus speed from ACPI"

2016-07-19T03:57:23Z

This reverts commit 55d38d060e999ca1a3ea6eb132105a0301e4cd04. There were too heavy merge conflicts and the driver code making use of this was not ready yet anyhow. So, we wait one cycle. Signed-off-by: Wolfram Sang

i2c: core: Add function for finding the bus speed from ACPI

2016-07-14T13:25:10Z

ACPI 5 specification doesn't have property for the I2C bus speed but I2cSerialBus resource descriptors which define each controller-slave connection define the maximum speed supported by that connection. Thus finding the maximum safe speed for the bus is to walk all I2cSerialBus resources that are associated to I2C controller and use the speed of slowest connection. Add function i2c_acpi_find_bus_speed() to the i2c-core that adapter drivers can call prior registering itself to core. This implies two-step walk through the I2cSerialBus resources: call to i2c_acpi_find_bus_speed() does the first scan and finds the safe bus speed that adapter drivers can set up. Adapter driver registration does the second scan when i2c-core creates the I2C slaves by calling the i2c_acpi_register_devices(). In that way the bus speed is set in case slave device probe gets called during registration and does communication. Implement this by reusing the existing ACPI I2C walk routines in the i2c-core. Extend them so that slowest connection speed is saved during the walk and I2C slaves are registered only when calling through the i2c_acpi_register_devices() with the i2c_adapter pointer. Signed-off-by: Jarkko Nikula Reviewed-by: Andy Shevchenko Acked-by: Mika Westerberg Signed-off-by: Wolfram Sang

i2c: smbus: add SMBus Host Notify support

2016-06-17T11:24:05Z

SMBus Host Notify allows a slave device to act as a master on a bus to notify the host of an interrupt. On Intel chipsets, the functionality is directly implemented in the firmware. We just need to export a function to call .alert() on the proper device driver. i2c_handle_smbus_host_notify() behaves like i2c_handle_smbus_alert(). When called, it schedules a task that will be able to sleep to go through the list of devices attached to the adapter. The current implementation allows one Host Notification to be scheduled while an other is running. Tested-by: Andrew Duggan Signed-off-by: Benjamin Tissoires Signed-off-by: Wolfram Sang

i2c: add a protocol parameter to the alert callback

2016-06-17T10:41:25Z

.alert() is meant to be generic, but there is currently no way for the device driver to know which protocol generated the alert. Add a parameter in .alert() to help the device driver to understand what is given in data. This patch is required to have the support of SMBus Host Notify protocol through .alert(). Tested-by: Andrew Duggan For hwmon: Acked-by: Guenter Roeck For IPMI: Acked-by: Corey Minyard Signed-off-by: Benjamin Tissoires Signed-off-by: Wolfram Sang

i2c: Add generic support passing secondary devices addresses

2016-06-13T20:32:09Z

Some I2C devices have multiple addresses assigned, for example each address corresponding to a different internal register map page of the device. So far drivers which need support for this have handled this with a driver specific and non-generic implementation, e.g. passing the additional address via platform data. This patch provides a new helper function called i2c_new_secondary_device() which is intended to provide a generic way to get the secondary address as well as instantiate a struct i2c_client for the secondary address. The function expects a pointer to the primary i2c_client, a name for the secondary address and an optional default address. The name is used as a handle to specify which secondary address to get. The default address is used as a fallback in case no secondary address was explicitly specified. In case no secondary address and no default address were specified the function returns NULL. For now the function only supports look-up of the secondary address from devicetree, but it can be extended in the future to for example support board files and/or ACPI. Signed-off-by: Jean-Michel Hautbois Acked-by: Rob Herring Acked-by: Mika Westerberg Signed-off-by: Wolfram Sang

i2c: mux: relax locking of the top i2c adapter during mux-locked muxing

2016-05-04T20:39:17Z

With a i2c topology like the following GPIO ---| ------ BAT1 | v / I2C -----+----------+---- MUX | \ EEPROM ------ BAT2 there is a locking problem with the GPIO controller since it is a client on the same i2c bus that it muxes. Transfers to the mux clients (e.g. BAT1) will lock the whole i2c bus prior to attempting to switch the mux to the correct i2c segment. In the above case, the GPIO device is an I/O expander with an i2c interface, and since the GPIO subsystem knows nothing (and rightfully so) about the lockless needs of the i2c mux code, this results in a deadlock when the GPIO driver issues i2c transfers to modify the mux. So, observing that while it is needed to have the i2c bus locked during the actual MUX update in order to avoid random garbage on the slave side, it is not strictly a must to have it locked over the whole sequence of a full select-transfer-deselect mux client operation. The mux itself needs to be locked, so transfers to clients behind the mux are serialized, and the mux needs to be stable during all i2c traffic (otherwise individual mux slave segments might see garbage, or worse). Introduce this new locking concept as "mux-locked" muxes, and call the pre-existing mux locking scheme "parent-locked". Modify the i2c mux locking so that muxes that are "mux-locked" locks only the muxes on the parent adapter instead of the whole i2c bus when there is a transfer to the slave side of the mux. This lock serializes transfers to the slave side of the muxes on the parent adapter. Add code to i2c-mux-gpio and i2c-mux-pinctrl that checks if all involved gpio/pinctrl devices have a parent that is an i2c adapter in the same adapter tree that is muxed, and request a "mux-locked mux" if that is the case. Modify the select-transfer-deselect code for "mux-locked" muxes so that each of the select-transfer-deselect ops locks the mux parent adapter individually. Signed-off-by: Peter Rosin Signed-off-by: Wolfram Sang

i2c: allow adapter drivers to override the adapter locking

2016-05-04T20:28:31Z

Add i2c_lock_bus() and i2c_unlock_bus(), which call the new lock_bus and unlock_bus ops in the adapter. These funcs/ops take an additional flags argument that indicates for what purpose the adapter is locked. There are two flags, I2C_LOCK_ROOT_ADAPTER and I2C_LOCK_SEGMENT, but they are both implemented the same. For now. Locking the root adapter means that the whole bus is locked, locking the segment means that only the current bus segment is locked (i.e. i2c traffic on the parent side of a mux is still allowed even if the child side of the mux is locked). Also support a trylock_bus op (but no function to call it, as it is not expected to be needed outside of the i2c core). Implement i2c_lock_adapter/i2c_unlock_adapter in terms of the new locking scheme (i.e. lock with the I2C_LOCK_ROOT_ADAPTER flag). Locking the root adapter and locking the segment is the same thing for all root adapters (e.g. in the normal case of a simple topology with no i2c muxes). The two locking variants are also the same for traditional muxes (aka parent-locked muxes). These muxes traverse the tree, locking each level as they go until they reach the root. This patch is preparatory for a later patch in the series introducing mux-locked muxes, which behave differently depending on the requested locking. Since all current users are using i2c_lock_adapter, which is a wrapper for I2C_LOCK_ROOT_ADAPTER, we only need to annotate the calls that will not need to lock the root adapter for mux-locked muxes. I.e. the instances that needs to use I2C_LOCK_SEGMENT instead of i2c_lock_adapter/I2C_LOCK_ROOT_ADAPTER. Those instances are in the i2c_transfer and i2c_smbus_xfer functions, so that mux-locked muxes can single out normal i2c accesses to its slave side and adjust the locking for those accesses. Signed-off-by: Peter Rosin Signed-off-by: Wolfram Sang

i2c: introduce helper function to get 8 bit address from a message

2016-04-11T16:54:59Z

Drivers do this in various ways, let's use one standard way of doing it. Note: I2C_M_RD is bit 0, so the code could be simplified. To be extremly robust and to advertise good coding practices, I still use the ternary operator and let the compilers do the optimizing job. Reviewed-by: Andy Shevchenko Signed-off-by: Wolfram Sang

i2c: create builtin_i2c_driver to avoid registration boilerplate

2016-01-13T10:06:03Z

In commit f309d4443130bf814e991f836e919dca22df37ae ("platform_device: better support builtin boilerplate avoidance") we introduced the builtin_driver macro. Here we use that support and extend it to I2C driver registration, so where a driver is clearly non-modular and builtin-only, we can register it in a similar fashion. And existing code that is clearly non-modular can be updated with the simple mapping of module_i2c_driver(...) ---> builtin_i2c_driver(...) We've essentially cloned the former to make the latter, and taken out the remove/module_exit parts since those never get used in a non-modular build of the code. A similar thing was done in commit b4eb6cdbbd13698704863f680c643c569909e1c2 ("PCI: Add builtin_pci_driver() to avoid registration boilerplate"). Signed-off-by: Paul Gortmaker Signed-off-by: Wolfram Sang

i2c: add generic routine to parse DT for timing information

2015-12-14T09:51:07Z

Inspired from the i2c-rk3x driver (thanks guys!) but refactored and extended. See built-in docs for further information. Signed-off-by: Wolfram Sang Reviewed-by: Mika Westerberg Signed-off-by: Wolfram Sang