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e151a1c288
The syscon implementation in U-Boot is different from that in Linux.
Thus, DT files imported from Linux do not work for U-Boot.
In U-Boot driver model, each node is bound to a dedicated driver
that is the most compatible to it. This design gets along with the
concept of DT, and the syscon in Linux originally worked like that.
However, Linux commit bdb0066df96e ("mfd: syscon: Decouple syscon
interface from platform devices") changed the behavior because it is
useful to let a device bind to another driver, but still work as a
syscon provider.
That change had happened before U-Boot initially supported the syscon
driver by commit 6f98b7504f ("dm: Add support for generic system
controllers (syscon)"). So, the U-Boot's syscon works differently
from the beginning. I'd say this is mis-implementation given that
DT is not oriented to a particular project, but Linux is the canon
of DT in practice.
The problem typically arises in the combination of "syscon" and
"simple-mfd" compatibles.
In Linux, they are orthogonal, i.e., the order between "syscon" and
"simple-mfd" does not matter at all.
Assume the following compatible.
compatible = "foo,bar-syscon", "syscon", "simple-mfd";
In U-Boot, this device node is bound to the syscon driver
(driver/core/syscon-uclass.c) since the "syscon" is found to be the
most compatible. Then, syscon_get_regmap() succeeds.
However,
compatible = "foo,bar-syscon", "simple-mfd", "syscon";
does not work because this node is bound to the simple-bus driver
(drivers/core/simple-bus.c) in favor of "simple-mfd" compatible.
The compatible string "syscon" is just dismissed.
Moreover,
compatible = "foo,bar-syscon", "syscon";
works like the first case because the syscon driver populates the
child devices. This is wrong because populating children is the job
of "simple-mfd" (or "simple-bus").
This commit ports syscon_node_to_regmap() from Linux. This API
does not require the given node to be bound to a driver in any way.
Reported-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
92 lines
2.6 KiB
C
92 lines
2.6 KiB
C
/* SPDX-License-Identifier: GPL-2.0+ */
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/*
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* Copyright (c) 2015 Google, Inc
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* Written by Simon Glass <sjg@chromium.org>
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*/
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#ifndef __SYSCON_H
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#define __SYSCON_H
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#include <dm/ofnode.h>
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#include <fdtdec.h>
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/**
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* struct syscon_uc_info - Information stored by the syscon UCLASS_UCLASS
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*
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* @regmap: Register map for this controller
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*/
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struct syscon_uc_info {
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struct regmap *regmap;
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};
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/* So far there are no ops so this is a placeholder */
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struct syscon_ops {
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};
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#define syscon_get_ops(dev) ((struct syscon_ops *)(dev)->driver->ops)
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#if CONFIG_IS_ENABLED(OF_PLATDATA)
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/*
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* We don't support 64-bit machines. If they are so resource-contrained that
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* they need to use OF_PLATDATA, something is horribly wrong with the
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* education of our hardware engineers.
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*
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* Update: 64-bit is now supported and we have an education crisis.
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*/
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struct syscon_base_platdata {
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fdt_val_t reg[2];
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};
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#endif
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/**
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* syscon_get_regmap() - Get access to a register map
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*
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* @dev: Device to check (UCLASS_SCON)
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* @info: Returns regmap for the device
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* @return 0 if OK, -ve on error
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*/
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struct regmap *syscon_get_regmap(struct udevice *dev);
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/**
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* syscon_get_regmap_by_driver_data() - Look up a controller by its ID
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*
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* Each system controller can be accessed by its driver data, which is
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* assumed to be unique through the scope of all system controllers that
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* are in use. This function looks up the controller given this driver data.
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*
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* @driver_data: Driver data value to look up
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* @devp: Returns the controller correponding to @driver_data
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* @return 0 on success, -ENODEV if the ID was not found, or other -ve error
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* code
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*/
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int syscon_get_by_driver_data(ulong driver_data, struct udevice **devp);
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/**
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* syscon_get_regmap_by_driver_data() - Look up a controller by its ID
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*
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* Each system controller can be accessed by its driver data, which is
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* assumed to be unique through the scope of all system controllers that
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* are in use. This function looks up the regmap given this driver data.
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*
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* @driver_data: Driver data value to look up
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* @return register map correponding to @driver_data, or -ve error code
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*/
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struct regmap *syscon_get_regmap_by_driver_data(ulong driver_data);
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/**
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* syscon_get_first_range() - get the first memory range from a syscon regmap
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*
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* @driver_data: Driver data value to look up
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* @return first region of register map correponding to @driver_data, or
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* -ve error code
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*/
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void *syscon_get_first_range(ulong driver_data);
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/**
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* syscon_node_to_regmap - get regmap from syscon
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*
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* @node: Device node of syscon
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*/
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struct regmap *syscon_node_to_regmap(ofnode node);
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#endif
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