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Diffstat (limited to 'arch/powerpc/include/asm/scom.h')
| -rw-r--r-- | arch/powerpc/include/asm/scom.h | 167 |
1 files changed, 167 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/scom.h b/arch/powerpc/include/asm/scom.h new file mode 100644 index 000000000..f5cde45b1 --- /dev/null +++ b/arch/powerpc/include/asm/scom.h @@ -0,0 +1,167 @@ +/* + * Copyright 2010 Benjamin Herrenschmidt, IBM Corp + * <benh@kernel.crashing.org> + * 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); + + 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 */ |