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/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* Copyright 2010 Benjamin Herrenschmidt, IBM Corp
* <benh@kernel.crashing.org>
* and David Gibson, IBM Corporation.
*/
#ifndef _ASM_POWERPC_SCOM_H
#define _ASM_POWERPC_SCOM_H
#ifdef __KERNEL__
#ifndef __ASSEMBLY__
#ifdef CONFIG_PPC_SCOM
/*
* The SCOM bus is a sideband bus used for accessing various internal
* registers of the processor or the chipset. The implementation details
* differ between processors and platforms, and the access method as
* well.
*
* This API allows to "map" ranges of SCOM register numbers associated
* with a given SCOM controller. The later must be represented by a
* device node, though some implementations might support NULL if there
* is no possible ambiguity
*
* Then, scom_read/scom_write can be used to accesses registers inside
* that range. The argument passed is a register number relative to
* the beginning of the range mapped.
*/
typedef void *scom_map_t;
/* Value for an invalid SCOM map */
#define SCOM_MAP_INVALID (NULL)
/* The scom_controller data structure is what the platform passes
* to the core code in scom_init, it provides the actual implementation
* of all the SCOM functions
*/
struct scom_controller {
scom_map_t (*map)(struct device_node *ctrl_dev, u64 reg, u64 count);
void (*unmap)(scom_map_t map);
int (*read)(scom_map_t map, u64 reg, u64 *value);
int (*write)(scom_map_t map, u64 reg, u64 value);
};
extern const struct scom_controller *scom_controller;
/**
* scom_init - Initialize the SCOM backend, called by the platform
* @controller: The platform SCOM controller
*/
static inline void scom_init(const struct scom_controller *controller)
{
scom_controller = controller;
}
/**
* scom_map_ok - Test is a SCOM mapping is successful
* @map: The result of scom_map to test
*/
static inline int scom_map_ok(scom_map_t map)
{
return map != SCOM_MAP_INVALID;
}
/**
* scom_map - Map a block of SCOM registers
* @ctrl_dev: Device node of the SCOM controller
* some implementations allow NULL here
* @reg: first SCOM register to map
* @count: Number of SCOM registers to map
*/
static inline scom_map_t scom_map(struct device_node *ctrl_dev,
u64 reg, u64 count)
{
return scom_controller->map(ctrl_dev, reg, count);
}
/**
* scom_find_parent - Find the SCOM controller for a device
* @dev: OF node of the device
*
* This is not meant for general usage, but in combination with
* scom_map() allows to map registers not represented by the
* device own scom-reg property. Useful for applying HW workarounds
* on things not properly represented in the device-tree for example.
*/
struct device_node *scom_find_parent(struct device_node *dev);
/**
* scom_map_device - Map a device's block of SCOM registers
* @dev: OF node of the device
* @index: Register bank index (index in "scom-reg" property)
*
* This function will use the device-tree binding for SCOM which
* is to follow "scom-parent" properties until it finds a node with
* a "scom-controller" property to find the controller. It will then
* use the "scom-reg" property which is made of reg/count pairs,
* each of them having a size defined by the controller's #scom-cells
* property
*/
extern scom_map_t scom_map_device(struct device_node *dev, int index);
/**
* scom_unmap - Unmap a block of SCOM registers
* @map: Result of scom_map is to be unmapped
*/
static inline void scom_unmap(scom_map_t map)
{
if (scom_map_ok(map))
scom_controller->unmap(map);
}
/**
* scom_read - Read a SCOM register
* @map: Result of scom_map
* @reg: Register index within that map
* @value: Updated with the value read
*
* Returns 0 (success) or a negative error code
*/
static inline int scom_read(scom_map_t map, u64 reg, u64 *value)
{
int rc;
rc = scom_controller->read(map, reg, value);
if (rc)
*value = 0xfffffffffffffffful;
return rc;
}
/**
* scom_write - Write to a SCOM register
* @map: Result of scom_map
* @reg: Register index within that map
* @value: Value to write
*
* Returns 0 (success) or a negative error code
*/
static inline int scom_write(scom_map_t map, u64 reg, u64 value)
{
return scom_controller->write(map, reg, value);
}
#endif /* CONFIG_PPC_SCOM */
#endif /* __ASSEMBLY__ */
#endif /* __KERNEL__ */
#endif /* _ASM_POWERPC_SCOM_H */
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