scom.h

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/*
 * Copyright 2010 Benjamin Herrenschmidt, IBM Corp
 *                <[email protected]>
 *     and        David Gibson, IBM Corporation.
 *
 *   This program is free software;  you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY;  without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
 *   the GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program;  if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#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);

    u64 (*read)(scom_map_t map, u32 reg);
    void (*write)(scom_map_t map, u32 reg, u64 value);
};

extern const struct scom_controller *scom_controller;

static inline void scom_init(const struct scom_controller *controller)
{
    scom_controller = controller;
}

static inline int scom_map_ok(scom_map_t map)
{
    return map != SCOM_MAP_INVALID;
}

static inline scom_map_t scom_map(struct device_node *ctrl_dev,
                  u64 reg, u64 count)
{
    return scom_controller->map(ctrl_dev, reg, count);
}

struct device_node *scom_find_parent(struct device_node *dev);


extern scom_map_t scom_map_device(struct device_node *dev, int index);


static inline void scom_unmap(scom_map_t map)
{
    if (scom_map_ok(map))
        scom_controller->unmap(map);
}

static inline u64 scom_read(scom_map_t map, u32 reg)
{
    return scom_controller->read(map, reg);
}

static inline void scom_write(scom_map_t map, u32 reg, u64 value)
{
    scom_controller->write(map, reg, value);
}

#endif /* CONFIG_PPC_SCOM */
#endif /* __ASSEMBLY__ */
#endif /* __KERNEL__ */
#endif /* _ASM_POWERPC_SCOM_H */