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: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: default avatarMichael Ellerman <michael@ellerman.id.au>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent cd852579
/*
* 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);
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;
/**
* 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
*/
static inline u64 scom_read(scom_map_t map, u32 reg)
{
return scom_controller->read(map, reg);
}
/**
* scom_write - Write to a SCOM register
* @map: Result of scom_map
* @reg: Register index within that map
* @value: Value to write
*/
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 */
......@@ -15,3 +15,10 @@ config PPC_MSI_BITMAP
source "arch/powerpc/sysdev/xics/Kconfig"
config PPC_SCOM
bool
config SCOM_DEBUGFS
bool "Expose SCOM controllers via debugfs"
depends on PPC_SCOM
default n
......@@ -58,6 +58,8 @@ ifeq ($(CONFIG_SUSPEND),y)
obj-$(CONFIG_6xx) += 6xx-suspend.o
endif
obj-$(CONFIG_PPC_SCOM) += scom.o
subdir-ccflags-$(CONFIG_PPC_WERROR) := -Werror
obj-$(CONFIG_PPC_XICS) += xics/
/*
* 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
*/
#include <linux/kernel.h>
#include <linux/debugfs.h>
#include <linux/slab.h>
#include <asm/prom.h>
#include <asm/scom.h>
const struct scom_controller *scom_controller;
EXPORT_SYMBOL_GPL(scom_controller);
struct device_node *scom_find_parent(struct device_node *node)
{
struct device_node *par, *tmp;
const u32 *p;
for (par = of_node_get(node); par;) {
if (of_get_property(par, "scom-controller", NULL))
break;
p = of_get_property(par, "scom-parent", NULL);
tmp = par;
if (p == NULL)
par = of_get_parent(par);
else
par = of_find_node_by_phandle(*p);
of_node_put(tmp);
}
return par;
}
EXPORT_SYMBOL_GPL(scom_find_parent);
scom_map_t scom_map_device(struct device_node *dev, int index)
{
struct device_node *parent;
unsigned int cells, size;
const u32 *prop;
u64 reg, cnt;
scom_map_t ret;
parent = scom_find_parent(dev);
if (parent == NULL)
return 0;
prop = of_get_property(parent, "#scom-cells", NULL);
cells = prop ? *prop : 1;
prop = of_get_property(dev, "scom-reg", &size);
if (!prop)
return 0;
size >>= 2;
if (index >= (size / (2*cells)))
return 0;
reg = of_read_number(&prop[index * cells * 2], cells);
cnt = of_read_number(&prop[index * cells * 2 + cells], cells);
ret = scom_map(parent, reg, cnt);
of_node_put(parent);
return ret;
}
EXPORT_SYMBOL_GPL(scom_map_device);
#ifdef CONFIG_SCOM_DEBUGFS
struct scom_debug_entry {
struct device_node *dn;
unsigned long addr;
scom_map_t map;
spinlock_t lock;
char name[8];
struct debugfs_blob_wrapper blob;
};
static int scom_addr_set(void *data, u64 val)
{
struct scom_debug_entry *ent = data;
ent->addr = 0;
scom_unmap(ent->map);
ent->map = scom_map(ent->dn, val, 1);
if (scom_map_ok(ent->map))
ent->addr = val;
else
return -EFAULT;
return 0;
}
static int scom_addr_get(void *data, u64 *val)
{
struct scom_debug_entry *ent = data;
*val = ent->addr;
return 0;
}
DEFINE_SIMPLE_ATTRIBUTE(scom_addr_fops, scom_addr_get, scom_addr_set,
"0x%llx\n");
static int scom_val_set(void *data, u64 val)
{
struct scom_debug_entry *ent = data;
if (!scom_map_ok(ent->map))
return -EFAULT;
scom_write(ent->map, 0, val);
return 0;
}
static int scom_val_get(void *data, u64 *val)
{
struct scom_debug_entry *ent = data;
if (!scom_map_ok(ent->map))
return -EFAULT;
*val = scom_read(ent->map, 0);
return 0;
}
DEFINE_SIMPLE_ATTRIBUTE(scom_val_fops, scom_val_get, scom_val_set,
"0x%llx\n");
static int scom_debug_init_one(struct dentry *root, struct device_node *dn,
int i)
{
struct scom_debug_entry *ent;
struct dentry *dir;
ent = kzalloc(sizeof(*ent), GFP_KERNEL);
if (!ent)
return -ENOMEM;
ent->dn = of_node_get(dn);
ent->map = SCOM_MAP_INVALID;
spin_lock_init(&ent->lock);
snprintf(ent->name, 8, "scom%d", i);
ent->blob.data = dn->full_name;
ent->blob.size = strlen(dn->full_name);
dir = debugfs_create_dir(ent->name, root);
if (!dir) {
of_node_put(dn);
kfree(ent);
return -1;
}
debugfs_create_file("addr", 0600, dir, ent, &scom_addr_fops);
debugfs_create_file("value", 0600, dir, ent, &scom_val_fops);
debugfs_create_blob("path", 0400, dir, &ent->blob);
return 0;
}
static int scom_debug_init(void)
{
struct device_node *dn;
struct dentry *root;
int i, rc;
root = debugfs_create_dir("scom", powerpc_debugfs_root);
if (!root)
return -1;
i = rc = 0;
for_each_node_with_property(dn, "scom-controller")
rc |= scom_debug_init_one(root, dn, i++);
return rc;
}
device_initcall(scom_debug_init);
#endif /* CONFIG_SCOM_DEBUGFS */
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