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u-boot/drivers/i2c/muxes/Makefile

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SPDX: Convert all of our single license tags to Linux Kernel style When U-Boot started using SPDX tags we were among the early adopters and there weren't a lot of other examples to borrow from. So we picked the area of the file that usually had a full license text and replaced it with an appropriate SPDX-License-Identifier: entry. Since then, the Linux Kernel has adopted SPDX tags and they place it as the very first line in a file (except where shebangs are used, then it's second line) and with slightly different comment styles than us. In part due to community overlap, in part due to better tag visibility and in part for other minor reasons, switch over to that style. This commit changes all instances where we have a single declared license in the tag as both the before and after are identical in tag contents. There's also a few places where I found we did not have a tag and have introduced one. Signed-off-by: Tom Rini <trini@konsulko.com>
2018-05-06 21:58:06 +00:00
# SPDX-License-Identifier: GPL-2.0+
dm: i2c: Add support for multiplexed I2C buses Add a new I2C_MUX uclass. Devices in this class can multiplex between several I2C buses, selecting them one at a time for use by the system. The multiplexing mechanism is left to the driver to decide - it may be controlled by GPIOs, for example. The uclass supports only two methods: select() and deselect(). The current mux state is expected to be stored in the mux itself since it is the only thing that knows how to make things work. The mux can record the current state and then avoid switching unless it is necessary. So select() can be skipped if the mux is already in the correct state. Also deselect() can be made a nop if required. Signed-off-by: Simon Glass <sjg@chromium.org>
2015-08-03 14:19:21 +00:00
#
# Copyright (c) 2015 Google, Inc
i2c: Add a mux for GPIO-based I2C bus arbitration While I2C supports multi-master buses this is difficult to get right. The implementation on the master side in software is quite complex. Clock-stretching and the arbitrary time that an I2C transaction can take make it difficult to share the bus fairly in the face of high traffic. When one or more masters can be reset independently part-way through a transaction it is hard to know the state of the bus. This driver provides a scheme based on two 'claim' GPIOs, one driven by the AP (Application Processor, meaning the main CPU) and one driven by the EC (Embedded Controller, a small CPU aimed at handling system tasks). With these they can communicate and reliably share the bus. This scheme has minimal overhead and involves very little code. It is used on snow to permit the EC and the AP to share access to the main system PMIC and battery. The scheme can survive reboots by either side without difficulty. This scheme has been tested in the field with millions of devices. Since U-Boot runs on the AP, the terminology used is 'our' claim GPIO, meaning the AP's, and 'their' claim GPIO, meaning the EC's. This terminology is used by the device tree bindings in Linux also. Signed-off-by: Simon Glass <sjg@chromium.org>
2015-08-03 14:19:22 +00:00
obj-$(CONFIG_I2C_ARB_GPIO_CHALLENGE) += i2c-arb-gpio-challenge.o
Link failure with CONFIG_SPL and CONFIG_I2C_MUX_PCA954x Fix for the case of a U-Boot configuration with CONFIG_SPL, CONFIG_I2C_MUX, CONFIG_I2C_MUX_PCA954x, no CONFIG_SPL_DM and no CONFIG_SPL_I2C_MUX. Without this fix linking of pca954x fails because dm_write_i2c does not exist because CONFIG_SPL_DM is not defined. Signed-off-by: Kees Trommel <kees.trommel.contractor@draeger.com> Cc: Heiko Schocher <hs@denx.de>
2020-08-03 14:49:47 +00:00
obj-$(CONFIG_I2C_MUX) += i2c-mux-uclass.o
i2c: muxes: Add support for TI PCA954X mux Add support for common TI i2c mux which is available on ZynqMP zcu102 board. DM i2c mux core code is selecting/deselecting bus before/after every command is performed that's why only one channel is active at a time. That's also the reason why deselect is just disable all available channels. Signed-off-by: Michal Simek <michal.simek@xilinx.com> Reviewed-by: Heiko Schocher <hs@denx.de> Reviewed-by: Simon Glass <sjg@chromium.org>
2016-04-25 08:50:42 +00:00
obj-$(CONFIG_I2C_MUX_PCA954x) += pca954x.o
i2c: muxes: add i2c gpio multiplexer driver Add an i2c mux driver providing access to i2c bus segments using a hardware MUX sitting on a master bus and controlled through gpio pins. E.G. something like: ---------- ---------- Bus segment 1 - - - - - | | SCL/SDA | |-------------- | | | |------------| | | | | | Bus segment 2 | | | Linux | GPIO 1..N | MUX |--------------- Devices | |------------| | | | | | | | Bus segment M | | | |---------------| | ---------- ---------- - - - - - SCL/SDA of the master I2C bus is multiplexed to bus segment 1..M according to the settings of the GPIO pins 1..N. Note commit log from kernel commit 92ed1a76("i2c: Add generic I2C multiplexer using GPIO API") Signed-off-by: Peng Fan <peng.fan@nxp.com> Tested-by: Peng Fan <peng.fan@nxp.com> (i.MX6QP-Sabreauto) Cc: Heiko Schocher <hs@denx.de> Cc: Stefano Babic <sbabic@denx.de> Cc: Simon Glass <sjg@chromium.org>
2017-08-14 10:00:05 +00:00
obj-$(CONFIG_I2C_MUX_GPIO) += i2c-mux-gpio.o
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