mdesc.c

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/* mdesc.c: Sun4V machine description handling.
 *
 * Copyright (C) 2007 David S. Miller <[e-mail]>
 */
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/bootmem.h>
#include <linux/log2.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/miscdevice.h>

#include <asm/hypervisor.h>
#include <asm/mdesc.h>
#include <asm/prom.h>
#include <asm/oplib.h>
#include <asm/smp.h>

/* Unlike the OBP device tree, the machine description is a full-on
 * DAG.  An arbitrary number of ARCs are possible from one
 * node to other nodes and thus we can't use the OBP device_node
 * data structure to represent these nodes inside of the kernel.
 *
 * Actually, it isn't even a DAG, because there are back pointers
 * which create cycles in the graph.
 *
 * mdesc_hdr and mdesc_elem describe the layout of the data structure
 * we get from the Hypervisor.
 */
struct mdesc_hdr {
	u32	version; /* Transport version */
	u32	node_sz; /* node block size */
	u32	name_sz; /* name block size */
	u32	data_sz; /* data block size */
} __attribute__((aligned(16)));

struct mdesc_elem {
	u8	tag;
#define MD_LIST_END	0x00
#define MD_NODE		0x4e
#define MD_NODE_END	0x45
#define MD_NOOP		0x20
#define MD_PROP_ARC	0x61
#define MD_PROP_VAL	0x76
#define MD_PROP_STR	0x73
#define MD_PROP_DATA	0x64
	u8	name_len;
	u16	resv;
	u32	name_offset;
	union {
		struct {
			u32	data_len;
			u32	data_offset;
		} data;
		u64	val;
	} d;
};

struct mdesc_mem_ops {
	struct mdesc_handle *(*alloc)(unsigned int mdesc_size);
	void (*free)(struct mdesc_handle *handle);
};

struct mdesc_handle {
	struct list_head	list;
	struct mdesc_mem_ops	*mops;
	void			*self_base;
	atomic_t		refcnt;
	unsigned int		handle_size;
	struct mdesc_hdr	mdesc;
};

static void mdesc_handle_init(struct mdesc_handle *hp,
			      unsigned int handle_size,
			      void *base)
{
	BUG_ON(((unsigned long)&hp->mdesc) & (16UL - 1));

	memset(hp, 0, handle_size);
	INIT_LIST_HEAD(&hp->list);
	hp->self_base = base;
	atomic_set(&hp->refcnt, 1);
	hp->handle_size = handle_size;
}

static struct mdesc_handle * __init mdesc_bootmem_alloc(unsigned int mdesc_size)
{
	struct mdesc_handle *hp;
	unsigned int handle_size, alloc_size;

	handle_size = (sizeof(struct mdesc_handle) -
		       sizeof(struct mdesc_hdr) +
		       mdesc_size);
	alloc_size = PAGE_ALIGN(handle_size);

	hp = __alloc_bootmem(alloc_size, PAGE_SIZE, 0UL);
	if (hp)
		mdesc_handle_init(hp, handle_size, hp);

	return hp;
}

static void mdesc_bootmem_free(struct mdesc_handle *hp)
{
	unsigned int alloc_size, handle_size = hp->handle_size;
	unsigned long start, end;

	BUG_ON(atomic_read(&hp->refcnt) != 0);
	BUG_ON(!list_empty(&hp->list));

	alloc_size = PAGE_ALIGN(handle_size);

	start = (unsigned long) hp;
	end = start + alloc_size;

	while (start < end) {
		struct page *p;

		p = virt_to_page(start);
		ClearPageReserved(p);
		__free_page(p);
		start += PAGE_SIZE;
	}
}

static struct mdesc_mem_ops bootmem_mdesc_ops = {
	.alloc = mdesc_bootmem_alloc,
	.free  = mdesc_bootmem_free,
};

static struct mdesc_handle *mdesc_kmalloc(unsigned int mdesc_size)
{
	unsigned int handle_size;
	void *base;

	handle_size = (sizeof(struct mdesc_handle) -
		       sizeof(struct mdesc_hdr) +
		       mdesc_size);

	base = kmalloc(handle_size + 15, GFP_KERNEL | __GFP_NOFAIL);
	if (base) {
		struct mdesc_handle *hp;
		unsigned long addr;

		addr = (unsigned long)base;
		addr = (addr + 15UL) & ~15UL;
		hp = (struct mdesc_handle *) addr;

		mdesc_handle_init(hp, handle_size, base);
		return hp;
	}

	return NULL;
}

static void mdesc_kfree(struct mdesc_handle *hp)
{
	BUG_ON(atomic_read(&hp->refcnt) != 0);
	BUG_ON(!list_empty(&hp->list));

	kfree(hp->self_base);
}

static struct mdesc_mem_ops kmalloc_mdesc_memops = {
	.alloc = mdesc_kmalloc,
	.free  = mdesc_kfree,
};

static struct mdesc_handle *mdesc_alloc(unsigned int mdesc_size,
					struct mdesc_mem_ops *mops)
{
	struct mdesc_handle *hp = mops->alloc(mdesc_size);

	if (hp)
		hp->mops = mops;

	return hp;
}

static void mdesc_free(struct mdesc_handle *hp)
{
	hp->mops->free(hp);
}

static struct mdesc_handle *cur_mdesc;
static LIST_HEAD(mdesc_zombie_list);
static DEFINE_SPINLOCK(mdesc_lock);

struct mdesc_handle *mdesc_grab(void)
{
	struct mdesc_handle *hp;
	unsigned long flags;

	spin_lock_irqsave(&mdesc_lock, flags);
	hp = cur_mdesc;
	if (hp)
		atomic_inc(&hp->refcnt);
	spin_unlock_irqrestore(&mdesc_lock, flags);

	return hp;
}
EXPORT_SYMBOL(mdesc_grab);

void mdesc_release(struct mdesc_handle *hp)
{
	unsigned long flags;

	spin_lock_irqsave(&mdesc_lock, flags);
	if (atomic_dec_and_test(&hp->refcnt)) {
		list_del_init(&hp->list);
		hp->mops->free(hp);
	}
	spin_unlock_irqrestore(&mdesc_lock, flags);
}
EXPORT_SYMBOL(mdesc_release);

static DEFINE_MUTEX(mdesc_mutex);
static struct mdesc_notifier_client *client_list;

void mdesc_register_notifier(struct mdesc_notifier_client *client)
{
	u64 node;

	mutex_lock(&mdesc_mutex);
	client->next = client_list;
	client_list = client;

	mdesc_for_each_node_by_name(cur_mdesc, node, client->node_name)
		client->add(cur_mdesc, node);

	mutex_unlock(&mdesc_mutex);
}

static const u64 *parent_cfg_handle(struct mdesc_handle *hp, u64 node)
{
	const u64 *id;
	u64 a;

	id = NULL;
	mdesc_for_each_arc(a, hp, node, MDESC_ARC_TYPE_BACK) {
		u64 target;

		target = mdesc_arc_target(hp, a);
		id = mdesc_get_property(hp, target,
					"cfg-handle", NULL);
		if (id)
			break;
	}

	return id;
}

/* Run 'func' on nodes which are in A but not in B.  */
static void invoke_on_missing(const char *name,
			      struct mdesc_handle *a,
			      struct mdesc_handle *b,
			      void (*func)(struct mdesc_handle *, u64))
{
	u64 node;

	mdesc_for_each_node_by_name(a, node, name) {
		int found = 0, is_vdc_port = 0;
		const char *name_prop;
		const u64 *id;
		u64 fnode;

		name_prop = mdesc_get_property(a, node, "name", NULL);
		if (name_prop && !strcmp(name_prop, "vdc-port")) {
			is_vdc_port = 1;
			id = parent_cfg_handle(a, node);
		} else
			id = mdesc_get_property(a, node, "id", NULL);

		if (!id) {
			printk(KERN_ERR "MD: Cannot find ID for %s node.\n",
			       (name_prop ? name_prop : name));
			continue;
		}

		mdesc_for_each_node_by_name(b, fnode, name) {
			const u64 *fid;

			if (is_vdc_port) {
				name_prop = mdesc_get_property(b, fnode,
							       "name", NULL);
				if (!name_prop ||
				    strcmp(name_prop, "vdc-port"))
					continue;
				fid = parent_cfg_handle(b, fnode);
				if (!fid) {
					printk(KERN_ERR "MD: Cannot find ID "
					       "for vdc-port node.\n");
					continue;
				}
			} else
				fid = mdesc_get_property(b, fnode,
							 "id", NULL);

			if (*id == *fid) {
				found = 1;
				break;
			}
		}
		if (!found)
			func(a, node);
	}
}

static void notify_one(struct mdesc_notifier_client *p,
		       struct mdesc_handle *old_hp,
		       struct mdesc_handle *new_hp)
{
	invoke_on_missing(p->node_name, old_hp, new_hp, p->remove);
	invoke_on_missing(p->node_name, new_hp, old_hp, p->add);
}

static void mdesc_notify_clients(struct mdesc_handle *old_hp,
				 struct mdesc_handle *new_hp)
{
	struct mdesc_notifier_client *p = client_list;

	while (p) {
		notify_one(p, old_hp, new_hp);
		p = p->next;
	}
}

void mdesc_update(void)
{
	unsigned long len, real_len, status;
	struct mdesc_handle *hp, *orig_hp;
	unsigned long flags;

	mutex_lock(&mdesc_mutex);

	(void) sun4v_mach_desc(0UL, 0UL, &len);

	hp = mdesc_alloc(len, &kmalloc_mdesc_memops);
	if (!hp) {
		printk(KERN_ERR "MD: mdesc alloc fails\n");
		goto out;
	}

	status = sun4v_mach_desc(__pa(&hp->mdesc), len, &real_len);
	if (status != HV_EOK || real_len > len) {
		printk(KERN_ERR "MD: mdesc reread fails with %lu\n",
		       status);
		atomic_dec(&hp->refcnt);
		mdesc_free(hp);
		goto out;
	}

	spin_lock_irqsave(&mdesc_lock, flags);
	orig_hp = cur_mdesc;
	cur_mdesc = hp;
	spin_unlock_irqrestore(&mdesc_lock, flags);

	mdesc_notify_clients(orig_hp, hp);

	spin_lock_irqsave(&mdesc_lock, flags);
	if (atomic_dec_and_test(&orig_hp->refcnt))
		mdesc_free(orig_hp);
	else
		list_add(&orig_hp->list, &mdesc_zombie_list);
	spin_unlock_irqrestore(&mdesc_lock, flags);

out:
	mutex_unlock(&mdesc_mutex);
}

static struct mdesc_elem *node_block(struct mdesc_hdr *mdesc)
{
	return (struct mdesc_elem *) (mdesc + 1);
}

static void *name_block(struct mdesc_hdr *mdesc)
{
	return ((void *) node_block(mdesc)) + mdesc->node_sz;
}

static void *data_block(struct mdesc_hdr *mdesc)
{
	return ((void *) name_block(mdesc)) + mdesc->name_sz;
}

u64 mdesc_node_by_name(struct mdesc_handle *hp,
		       u64 from_node, const char *name)
{
	struct mdesc_elem *ep = node_block(&hp->mdesc);
	const char *names = name_block(&hp->mdesc);
	u64 last_node = hp->mdesc.node_sz / 16;
	u64 ret;

	if (from_node == MDESC_NODE_NULL) {
		ret = from_node = 0;
	} else if (from_node >= last_node) {
		return MDESC_NODE_NULL;
	} else {
		ret = ep[from_node].d.val;
	}

	while (ret < last_node) {
		if (ep[ret].tag != MD_NODE)
			return MDESC_NODE_NULL;
		if (!strcmp(names + ep[ret].name_offset, name))
			break;
		ret = ep[ret].d.val;
	}
	if (ret >= last_node)
		ret = MDESC_NODE_NULL;
	return ret;
}
EXPORT_SYMBOL(mdesc_node_by_name);

const void *mdesc_get_property(struct mdesc_handle *hp, u64 node,
			       const char *name, int *lenp)
{
	const char *names = name_block(&hp->mdesc);
	u64 last_node = hp->mdesc.node_sz / 16;
	void *data = data_block(&hp->mdesc);
	struct mdesc_elem *ep;

	if (node == MDESC_NODE_NULL || node >= last_node)
		return NULL;

	ep = node_block(&hp->mdesc) + node;
	ep++;
	for (; ep->tag != MD_NODE_END; ep++) {
		void *val = NULL;
		int len = 0;

		switch (ep->tag) {
		case MD_PROP_VAL:
			val = &ep->d.val;
			len = 8;
			break;

		case MD_PROP_STR:
		case MD_PROP_DATA:
			val = data + ep->d.data.data_offset;
			len = ep->d.data.data_len;
			break;

		default:
			break;
		}
		if (!val)
			continue;

		if (!strcmp(names + ep->name_offset, name)) {
			if (lenp)
				*lenp = len;
			return val;
		}
	}