168 lines
4.9 KiB
C
168 lines
4.9 KiB
C
/*
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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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int (*read)(scom_map_t map, u64 reg, u64 *value);
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int (*write)(scom_map_t map, u64 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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* @value: Updated with the value read
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*
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* Returns 0 (success) or a negative error code
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*/
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static inline int scom_read(scom_map_t map, u64 reg, u64 *value)
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{
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int rc;
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rc = scom_controller->read(map, reg, value);
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if (rc)
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*value = 0xfffffffffffffffful;
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return rc;
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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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* Returns 0 (success) or a negative error code
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*/
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static inline int scom_write(scom_map_t map, u64 reg, u64 value)
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{
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return 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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