powerpc: Add SCOM infrastructure
SCOM is a side-band configuration bus implemented on some processors. This code provides a way for code to map and operate on devices via SCOM, while the details of how that is implemented is left up to a SCOM "controller" in the platform code. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Michael Ellerman <michael@ellerman.id.au> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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Benjamin Herrenschmidt
parent
cd85257905
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ab814b938d
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/*
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* Copyright 2010 Benjamin Herrenschmidt, IBM Corp
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* <benh@kernel.crashing.org>
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* and David Gibson, IBM Corporation.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
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* the GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#ifndef _ASM_POWERPC_SCOM_H
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#define _ASM_POWERPC_SCOM_H
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#ifdef __KERNEL__
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#ifndef __ASSEMBLY__
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#ifdef CONFIG_PPC_SCOM
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/*
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* The SCOM bus is a sideband bus used for accessing various internal
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* registers of the processor or the chipset. The implementation details
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* differ between processors and platforms, and the access method as
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* well.
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*
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* This API allows to "map" ranges of SCOM register numbers associated
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* with a given SCOM controller. The later must be represented by a
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* device node, though some implementations might support NULL if there
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* is no possible ambiguity
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*
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* Then, scom_read/scom_write can be used to accesses registers inside
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* that range. The argument passed is a register number relative to
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* the beginning of the range mapped.
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*/
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typedef void *scom_map_t;
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/* Value for an invalid SCOM map */
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#define SCOM_MAP_INVALID (NULL)
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/* The scom_controller data structure is what the platform passes
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* to the core code in scom_init, it provides the actual implementation
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* of all the SCOM functions
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*/
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struct scom_controller {
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scom_map_t (*map)(struct device_node *ctrl_dev, u64 reg, u64 count);
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void (*unmap)(scom_map_t map);
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u64 (*read)(scom_map_t map, u32 reg);
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void (*write)(scom_map_t map, u32 reg, u64 value);
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};
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extern const struct scom_controller *scom_controller;
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/**
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* scom_init - Initialize the SCOM backend, called by the platform
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* @controller: The platform SCOM controller
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*/
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static inline void scom_init(const struct scom_controller *controller)
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{
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scom_controller = controller;
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}
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/**
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* scom_map_ok - Test is a SCOM mapping is successful
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* @map: The result of scom_map to test
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*/
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static inline int scom_map_ok(scom_map_t map)
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{
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return map != SCOM_MAP_INVALID;
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}
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/**
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* scom_map - Map a block of SCOM registers
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* @ctrl_dev: Device node of the SCOM controller
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* some implementations allow NULL here
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* @reg: first SCOM register to map
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* @count: Number of SCOM registers to map
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*/
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static inline scom_map_t scom_map(struct device_node *ctrl_dev,
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u64 reg, u64 count)
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{
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return scom_controller->map(ctrl_dev, reg, count);
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}
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/**
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* scom_find_parent - Find the SCOM controller for a device
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* @dev: OF node of the device
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*
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* This is not meant for general usage, but in combination with
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* scom_map() allows to map registers not represented by the
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* device own scom-reg property. Useful for applying HW workarounds
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* on things not properly represented in the device-tree for example.
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*/
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struct device_node *scom_find_parent(struct device_node *dev);
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/**
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* scom_map_device - Map a device's block of SCOM registers
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* @dev: OF node of the device
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* @index: Register bank index (index in "scom-reg" property)
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*
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* This function will use the device-tree binding for SCOM which
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* is to follow "scom-parent" properties until it finds a node with
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* a "scom-controller" property to find the controller. It will then
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* use the "scom-reg" property which is made of reg/count pairs,
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* each of them having a size defined by the controller's #scom-cells
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* property
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*/
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extern scom_map_t scom_map_device(struct device_node *dev, int index);
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/**
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* scom_unmap - Unmap a block of SCOM registers
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* @map: Result of scom_map is to be unmapped
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*/
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static inline void scom_unmap(scom_map_t map)
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{
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if (scom_map_ok(map))
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scom_controller->unmap(map);
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}
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/**
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* scom_read - Read a SCOM register
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* @map: Result of scom_map
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* @reg: Register index within that map
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*/
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static inline u64 scom_read(scom_map_t map, u32 reg)
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{
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return scom_controller->read(map, reg);
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}
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/**
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* scom_write - Write to a SCOM register
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* @map: Result of scom_map
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* @reg: Register index within that map
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* @value: Value to write
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*/
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static inline void scom_write(scom_map_t map, u32 reg, u64 value)
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{
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scom_controller->write(map, reg, value);
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}
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#endif /* CONFIG_PPC_SCOM */
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#endif /* __ASSEMBLY__ */
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#endif /* __KERNEL__ */
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#endif /* _ASM_POWERPC_SCOM_H */
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@ -15,3 +15,10 @@ config PPC_MSI_BITMAP
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source "arch/powerpc/sysdev/xics/Kconfig"
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config PPC_SCOM
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bool
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config SCOM_DEBUGFS
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bool "Expose SCOM controllers via debugfs"
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depends on PPC_SCOM
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default n
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@ -58,6 +58,8 @@ ifeq ($(CONFIG_SUSPEND),y)
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obj-$(CONFIG_6xx) += 6xx-suspend.o
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endif
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obj-$(CONFIG_PPC_SCOM) += scom.o
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subdir-ccflags-$(CONFIG_PPC_WERROR) := -Werror
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obj-$(CONFIG_PPC_XICS) += xics/
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@ -0,0 +1,192 @@
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/*
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* Copyright 2010 Benjamin Herrenschmidt, IBM Corp
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* <benh@kernel.crashing.org>
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* and David Gibson, IBM Corporation.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
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* the GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include <linux/kernel.h>
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#include <linux/debugfs.h>
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#include <linux/slab.h>
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#include <asm/prom.h>
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#include <asm/scom.h>
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const struct scom_controller *scom_controller;
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EXPORT_SYMBOL_GPL(scom_controller);
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struct device_node *scom_find_parent(struct device_node *node)
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{
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struct device_node *par, *tmp;
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const u32 *p;
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for (par = of_node_get(node); par;) {
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if (of_get_property(par, "scom-controller", NULL))
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break;
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p = of_get_property(par, "scom-parent", NULL);
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tmp = par;
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if (p == NULL)
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par = of_get_parent(par);
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else
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par = of_find_node_by_phandle(*p);
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of_node_put(tmp);
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}
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return par;
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}
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EXPORT_SYMBOL_GPL(scom_find_parent);
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scom_map_t scom_map_device(struct device_node *dev, int index)
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{
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struct device_node *parent;
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unsigned int cells, size;
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const u32 *prop;
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u64 reg, cnt;
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scom_map_t ret;
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parent = scom_find_parent(dev);
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if (parent == NULL)
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return 0;
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prop = of_get_property(parent, "#scom-cells", NULL);
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cells = prop ? *prop : 1;
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prop = of_get_property(dev, "scom-reg", &size);
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if (!prop)
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return 0;
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size >>= 2;
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if (index >= (size / (2*cells)))
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return 0;
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reg = of_read_number(&prop[index * cells * 2], cells);
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cnt = of_read_number(&prop[index * cells * 2 + cells], cells);
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ret = scom_map(parent, reg, cnt);
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of_node_put(parent);
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return ret;
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}
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EXPORT_SYMBOL_GPL(scom_map_device);
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#ifdef CONFIG_SCOM_DEBUGFS
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struct scom_debug_entry {
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struct device_node *dn;
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unsigned long addr;
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scom_map_t map;
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spinlock_t lock;
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char name[8];
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struct debugfs_blob_wrapper blob;
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};
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static int scom_addr_set(void *data, u64 val)
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{
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struct scom_debug_entry *ent = data;
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ent->addr = 0;
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scom_unmap(ent->map);
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ent->map = scom_map(ent->dn, val, 1);
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if (scom_map_ok(ent->map))
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ent->addr = val;
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else
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return -EFAULT;
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return 0;
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}
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static int scom_addr_get(void *data, u64 *val)
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{
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struct scom_debug_entry *ent = data;
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*val = ent->addr;
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return 0;
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}
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DEFINE_SIMPLE_ATTRIBUTE(scom_addr_fops, scom_addr_get, scom_addr_set,
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"0x%llx\n");
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static int scom_val_set(void *data, u64 val)
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{
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struct scom_debug_entry *ent = data;
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if (!scom_map_ok(ent->map))
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return -EFAULT;
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scom_write(ent->map, 0, val);
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return 0;
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}
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static int scom_val_get(void *data, u64 *val)
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{
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struct scom_debug_entry *ent = data;
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if (!scom_map_ok(ent->map))
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return -EFAULT;
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*val = scom_read(ent->map, 0);
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return 0;
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}
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DEFINE_SIMPLE_ATTRIBUTE(scom_val_fops, scom_val_get, scom_val_set,
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"0x%llx\n");
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static int scom_debug_init_one(struct dentry *root, struct device_node *dn,
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int i)
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{
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struct scom_debug_entry *ent;
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struct dentry *dir;
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ent = kzalloc(sizeof(*ent), GFP_KERNEL);
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if (!ent)
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return -ENOMEM;
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ent->dn = of_node_get(dn);
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ent->map = SCOM_MAP_INVALID;
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spin_lock_init(&ent->lock);
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snprintf(ent->name, 8, "scom%d", i);
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ent->blob.data = dn->full_name;
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ent->blob.size = strlen(dn->full_name);
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dir = debugfs_create_dir(ent->name, root);
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if (!dir) {
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of_node_put(dn);
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kfree(ent);
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return -1;
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}
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debugfs_create_file("addr", 0600, dir, ent, &scom_addr_fops);
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debugfs_create_file("value", 0600, dir, ent, &scom_val_fops);
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debugfs_create_blob("path", 0400, dir, &ent->blob);
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return 0;
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}
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static int scom_debug_init(void)
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{
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struct device_node *dn;
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struct dentry *root;
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int i, rc;
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root = debugfs_create_dir("scom", powerpc_debugfs_root);
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if (!root)
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return -1;
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i = rc = 0;
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for_each_node_with_property(dn, "scom-controller")
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rc |= scom_debug_init_one(root, dn, i++);
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return rc;
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}
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device_initcall(scom_debug_init);
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#endif /* CONFIG_SCOM_DEBUGFS */
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