sq.c

// SPDX-License-Identifier: GPL-2.0
/*
 * arch/sh/kernel/cpu/sh4/sq.c
 *
 * General management API for SH-4 integrated Store Queues
 *
 * Copyright (C) 2001 - 2006  Paul Mundt
 * Copyright (C) 2001, 2002  M. R. Brown
 */
#include <linux/init.h>
#include <linux/cpu.h>
#include <linux/bitmap.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/mm.h>
#include <linux/io.h>
#include <linux/prefetch.h>
#include <asm/page.h>
#include <asm/cacheflush.h>
#include <cpu/sq.h>

struct sq_mapping;

struct sq_mapping {
	const char *name;

	unsigned long sq_addr;
	unsigned long addr;
	unsigned int size;

	struct sq_mapping *next;
};

static struct sq_mapping *sq_mapping_list;
static DEFINE_SPINLOCK(sq_mapping_lock);
static struct kmem_cache *sq_cache;
static unsigned long *sq_bitmap;

#define store_queue_barrier()			\
do {						\
	(void)__raw_readl(P4SEG_STORE_QUE);	\
	__raw_writel(0, P4SEG_STORE_QUE + 0);	\
	__raw_writel(0, P4SEG_STORE_QUE + 8);	\
} while (0);

/**
 * sq_flush_range - Flush (prefetch) a specific SQ range
 * @start: the store queue address to start flushing from
 * @len: the length to flush
 *
 * Flushes the store queue cache from @start to @start + @len in a
 * linear fashion.
 */
void sq_flush_range(unsigned long start, unsigned int len)
{
	unsigned long *sq = (unsigned long *)start;

	/* Flush the queues */
	for (len >>= 5; len--; sq += 8)
		prefetchw(sq);

	/* Wait for completion */
	store_queue_barrier();
}
EXPORT_SYMBOL(sq_flush_range);

static inline void sq_mapping_list_add(struct sq_mapping *map)
{
	struct sq_mapping **p, *tmp;

	spin_lock_irq(&sq_mapping_lock);

	p = &sq_mapping_list;
	while ((tmp = *p) != NULL)
		p = &tmp->next;

	map->next = tmp;
	*p = map;

	spin_unlock_irq(&sq_mapping_lock);
}

static inline void sq_mapping_list_del(struct sq_mapping *map)
{
	struct sq_mapping **p, *tmp;

	spin_lock_irq(&sq_mapping_lock);

	for (p = &sq_mapping_list; (tmp = *p); p = &tmp->next)
		if (tmp == map) {
			*p = tmp->next;
			break;
		}

	spin_unlock_irq(&sq_mapping_lock);
}

static int __sq_remap(struct sq_mapping *map, pgprot_t prot)
{
#if defined(CONFIG_MMU)
	struct vm_struct *vma;

	vma = __get_vm_area_caller(map->size, VM_IOREMAP, map->sq_addr,
			SQ_ADDRMAX, __builtin_return_address(0));
	if (!vma)
		return -ENOMEM;

	vma->phys_addr = map->addr;

	if (ioremap_page_range((unsigned long)vma->addr,
			       (unsigned long)vma->addr + map->size,
			       vma->phys_addr, prot)) {
		vunmap(vma->addr);
		return -EAGAIN;
	}
#else
	/*
	 * Without an MMU (or with it turned off), this is much more
	 * straightforward, as we can just load up each queue's QACR with
	 * the physical address appropriately masked.
	 */
	__raw_writel(((map->addr >> 26) << 2) & 0x1c, SQ_QACR0);
	__raw_writel(((map->addr >> 26) << 2) & 0x1c, SQ_QACR1);
#endif

	return 0;
}

/**
 * sq_remap - Map a physical address through the Store Queues
 * @phys: Physical address of mapping.
 * @size: Length of mapping.
 * @name: User invoking mapping.
 * @prot: Protection bits.
 *
 * Remaps the physical address @phys through the next available store queue
 * address of @size length. @name is logged at boot time as well as through
 * the sysfs interface.
 */
unsigned long sq_remap(unsigned long phys, unsigned int size,
		       const char *name, pgprot_t prot)
{
	struct sq_mapping *map;
	unsigned long end;
	unsigned int psz;
	int ret, page;

	/* Don't allow wraparound or zero size */
	end = phys + size - 1;
	if (unlikely(!size || end < phys))
		return -EINVAL;
	/* Don't allow anyone to remap normal memory.. */
	if (unlikely(phys < virt_to_phys(high_memory)))
		return -EINVAL;

	phys &= PAGE_MASK;
	size = PAGE_ALIGN(end + 1) - phys;

	map = kmem_cache_alloc(sq_cache, GFP_KERNEL);
	if (unlikely(!map))
		return -ENOMEM;

	map->addr = phys;
	map->size = size;
	map->name = name;

	page = bitmap_find_free_region(sq_bitmap, 0x04000000 >> PAGE_SHIFT,
				       get_order(map->size));
	if (unlikely(page < 0)) {
		ret = -ENOSPC;
		goto out;
	}

	map->sq_addr = P4SEG_STORE_QUE + (page << PAGE_SHIFT);

	ret = __sq_remap(map, prot);
	if (unlikely(ret != 0))
		goto out;

	psz = (size + (PAGE_SIZE - 1)) >> PAGE_SHIFT;
	pr_info("sqremap: %15s  [%4d page%s]  va 0x%08lx   pa 0x%08lx\n",
		likely(map->name) ? map->name : "???",
		psz, psz == 1 ? " " : "s",
		map->sq_addr, map->addr);

	sq_mapping_list_add(map);

	return map->sq_addr;

out:
	kmem_cache_free(sq_cache, map);
	return ret;
}
EXPORT_SYMBOL(sq_remap);

/**
 * sq_unmap - Unmap a Store Queue allocation
 * @vaddr: Pre-allocated Store Queue mapping.
 *
 * Unmaps the store queue allocation @map that was previously created by
 * sq_remap(). Also frees up the pte that was previously inserted into
 * the kernel page table and discards the UTLB translation.
 */
void sq_unmap(unsigned long vaddr)
{
	struct sq_mapping **p, *map;
	int page;

	for (p = &sq_mapping_list; (map = *p); p = &map->next)
		if (map->sq_addr == vaddr)
			break;

	if (unlikely(!map)) {
		printk("%s: bad store queue address 0x%08lx\n",
		       __func__, vaddr);
		return;
	}

	page = (map->sq_addr - P4SEG_STORE_QUE) >> PAGE_SHIFT;
	bitmap_release_region(sq_bitmap, page, get_order(map->size));

#ifdef CONFIG_MMU
	{
		/*
		 * Tear down the VMA in the MMU case.
		 */
		struct vm_struct *vma;

		vma = remove_vm_area((void *)(map->sq_addr & PAGE_MASK));
		if (!vma) {
			printk(KERN_ERR "%s: bad address 0x%08lx\n",
			       __func__, map->sq_addr);
			return;
		}
	}
#endif

	sq_mapping_list_del(map);

	kmem_cache_free(sq_cache, map);
}
EXPORT_SYMBOL(sq_unmap);

/*
 * Needlessly complex sysfs interface. Unfortunately it doesn't seem like
 * there is any other easy way to add things on a per-cpu basis without
 * putting the directory entries somewhere stupid and having to create
 * links in sysfs by hand back in to the per-cpu directories.
 *
 * Some day we may want to have an additional abstraction per store
 * queue, but considering the kobject hell we already have to deal with,
 * it's simply not worth the trouble.
 */
static struct kobject *sq_kobject[NR_CPUS];

struct sq_sysfs_attr {
	struct attribute attr;
	ssize_t (*show)(char *buf);
	ssize_t (*store)(const char *buf, size_t count);
};

#define to_sq_sysfs_attr(a)	container_of(a, struct sq_sysfs_attr, attr)

static ssize_t sq_sysfs_show(struct kobject *kobj, struct attribute *attr,
			     char *buf)
{
	struct sq_sysfs_attr *sattr = to_sq_sysfs_attr(attr);

	if (likely(sattr->show))
		return sattr->show(buf);

	return -EIO;
}

static ssize_t sq_sysfs_store(struct kobject *kobj, struct attribute *attr,
			      const char *buf, size_t count)
{
	struct sq_sysfs_attr *sattr = to_sq_sysfs_attr(attr);

	if (likely(sattr->store))
		return sattr->store(buf, count);

	return -EIO;
}

static ssize_t mapping_show(char *buf)
{
	struct sq_mapping **list, *entry;
	char *p = buf;

	for (list = &sq_mapping_list; (entry = *list); list = &entry->next)
		p += sprintf(p, "%08lx-%08lx [%08lx]: %s\n",
			     entry->sq_addr, entry->sq_addr + entry->size,
			     entry->addr, entry->name);

	return p - buf;
}

static ssize_t mapping_store(const char *buf, size_t count)
{
	unsigned long base = 0, len = 0;

	sscanf(buf, "%lx %lx", &base, &len);
	if (!base)
		return -EIO;

	if (likely(len)) {
		int ret = sq_remap(base, len, "Userspace", PAGE_SHARED);
		if (ret < 0)
			return ret;
	} else
		sq_unmap(base);

	return count;
}

static struct sq_sysfs_attr mapping_attr =
	__ATTR(mapping, 0644, mapping_show, mapping_store);

static struct attribute *sq_sysfs_attrs[] = {
	&mapping_attr.attr,
	NULL,
};
ATTRIBUTE_GROUPS(sq_sysfs);

static const struct sysfs_ops sq_sysfs_ops = {
	.show	= sq_sysfs_show,
	.store	= sq_sysfs_store,
};

static struct kobj_type ktype_percpu_entry = {
	.sysfs_ops	= &sq_sysfs_ops,
	.default_groups	= sq_sysfs_groups,
};

static int sq_dev_add(struct device *dev, struct subsys_interface *sif)
{
	unsigned int cpu = dev->id;
	struct kobject *kobj;
	int error;

	sq_kobject[cpu] = kzalloc(sizeof(struct kobject), GFP_KERNEL);
	if (unlikely(!sq_kobject[cpu]))
		return -ENOMEM;

	kobj = sq_kobject[cpu];
	error = kobject_init_and_add(kobj, &ktype_percpu_entry, &dev->kobj,
				     "%s", "sq");
	if (!error)
		kobject_uevent(kobj, KOBJ_ADD);
	return error;
}

static void sq_dev_remove(struct device *dev, struct subsys_interface *sif)
{
	unsigned int cpu = dev->id;
	struct kobject *kobj = sq_kobject[cpu];

	kobject_put(kobj);
}

static struct subsys_interface sq_interface = {
	.name		= "sq",
	.subsys		= &cpu_subsys,
	.add_dev	= sq_dev_add,
	.remove_dev	= sq_dev_remove,
};

static int __init sq_api_init(void)
{
	unsigned int nr_pages = 0x04000000 >> PAGE_SHIFT;
	int ret = -ENOMEM;

	printk(KERN_NOTICE "sq: Registering store queue API.\n");

	sq_cache = kmem_cache_create("store_queue_cache",
				sizeof(struct sq_mapping), 0, 0, NULL);
	if (unlikely(!sq_cache))
		return ret;

	sq_bitmap = bitmap_zalloc(nr_pages, GFP_KERNEL);
	if (unlikely(!sq_bitmap))
		goto out;

	ret = subsys_interface_register(&sq_interface);
	if (unlikely(ret != 0))
		goto out;

	return 0;

out:
	bitmap_free(sq_bitmap);
	kmem_cache_destroy(sq_cache);

	return ret;
}

static void __exit sq_api_exit(void)
{
	subsys_interface_unregister(&sq_interface);
	bitmap_free(sq_bitmap);
	kmem_cache_destroy(sq_cache);
}

module_init(sq_api_init);
module_exit(sq_api_exit);

MODULE_AUTHOR("Paul Mundt <[email protected]>, M. R. Brown <[email protected]>");
MODULE_DESCRIPTION("Simple API for SH-4 integrated Store Queues");
MODULE_LICENSE("GPL");