sh: trapped io support V2

The idea is that we want to get rid of the in/out/readb/writeb callbacks from
the machvec and replace that with simple inline read and write operations to
memory. Fast and simple for most hardware devices (think pci).

Some devices require special treatment though - like 16-bit only CF devices -
so we need to have some method to hook in callbacks.

This patch makes it possible to add a per-device trap generating filter. This
way we can get maximum performance of sane hardware - which doesn't need this
filter - and crappy hardware works but gets punished by a performance hit.

V2 changes things around a bit and replaces io access callbacks with a
simple minimum_bus_width value. In the future we can add stride as well.

Signed-off-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 269 insertions, 0 deletions

diff --git a/arch/sh/kernel/io_trapped.c b/arch/sh/kernel/io_trapped.c
new file mode 100644
index 00000000000..0bfdc9a34e1
--- /dev/null
+++ b/arch/sh/kernel/io_trapped.c
@@ -0,0 +1,269 @@
+/*
+ * Trapped io support
+ *
+ * Copyright (C) 2008 Magnus Damm
+ *
+ * Intercept io operations by trapping.
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/bitops.h>
+#include <linux/vmalloc.h>
+#include <asm/system.h>
+#include <asm/mmu_context.h>
+#include <asm/uaccess.h>
+#include <asm/io.h>
+#include <asm/io_trapped.h>
+
+#define TRAPPED_PAGES_MAX 16
+#define MAX(a, b) (((a) >= (b)) ? (a) : (b))
+
+#ifdef CONFIG_HAS_IOPORT
+LIST_HEAD(trapped_io);
+#endif
+#ifdef CONFIG_HAS_IOMEM
+LIST_HEAD(trapped_mem);
+#endif
+static DEFINE_SPINLOCK(trapped_lock);
+
+int __init register_trapped_io(struct trapped_io *tiop)
+{
+	struct resource *res;
+	unsigned long len = 0, flags = 0;
+	struct page *pages[TRAPPED_PAGES_MAX];
+	int k, n;
+
+	/* structure must be page aligned */
+	if ((unsigned long)tiop & (PAGE_SIZE - 1))
+		goto bad;
+
+	for (k = 0; k < tiop->num_resources; k++) {
+		res = tiop->resource + k;
+		len += roundup((res->end - res->start) + 1, PAGE_SIZE);
+		flags |= res->flags;
+	}
+
+	/* support IORESOURCE_IO _or_ MEM, not both */
+	if (hweight_long(flags) != 1)
+		goto bad;
+
+	n = len >> PAGE_SHIFT;
+
+	if (n >= TRAPPED_PAGES_MAX)
+		goto bad;
+
+	for (k = 0; k < n; k++)
+		pages[k] = virt_to_page(tiop);
+
+	tiop->virt_base = vmap(pages, n, VM_MAP, PAGE_NONE);
+	if (!tiop->virt_base)
+		goto bad;
+
+	len = 0;
+	for (k = 0; k < tiop->num_resources; k++) {
+		res = tiop->resource + k;
+		pr_info("trapped io 0x%08lx overrides %s 0x%08lx\n",
+		       (unsigned long)(tiop->virt_base + len),
+		       res->flags & IORESOURCE_IO ? "io" : "mmio",
+		       (unsigned long)res->start);
+		len += roundup((res->end - res->start) + 1, PAGE_SIZE);
+	}
+
+	tiop->magic = IO_TRAPPED_MAGIC;
+	INIT_LIST_HEAD(&tiop->list);
+	spin_lock_irq(&trapped_lock);
+	if (flags & IORESOURCE_IO)
+		list_add(&tiop->list, &trapped_io);
+	if (flags & IORESOURCE_MEM)
+		list_add(&tiop->list, &trapped_mem);
+	spin_unlock_irq(&trapped_lock);
+
+	return 0;
+ bad:
+	pr_warning("unable to install trapped io filter\n");
+	return -1;
+}
+
+void __iomem *match_trapped_io_handler(struct list_head *list,
+				       unsigned long offset,
+				       unsigned long size)
+{
+	unsigned long voffs;
+	struct trapped_io *tiop;
+	struct resource *res;
+	int k, len;
+
+	spin_lock_irq(&trapped_lock);
+	list_for_each_entry(tiop, list, list) {
+		voffs = 0;
+		for (k = 0; k < tiop->num_resources; k++) {
+			res = tiop->resource + k;
+			if (res->start == offset) {
+				spin_unlock_irq(&trapped_lock);
+				return tiop->virt_base + voffs;
+			}
+
+			len = (res->end - res->start) + 1;
+			voffs += roundup(len, PAGE_SIZE);
+		}
+	}
+	spin_unlock_irq(&trapped_lock);
+	return NULL;
+}
+
+static struct trapped_io *lookup_tiop(unsigned long address)
+{
+	pgd_t *pgd_k;
+	pud_t *pud_k;
+	pmd_t *pmd_k;
+	pte_t *pte_k;
+	pte_t entry;
+
+	pgd_k = swapper_pg_dir + pgd_index(address);
+	if (!pgd_present(*pgd_k))
+		return NULL;
+
+	pud_k = pud_offset(pgd_k, address);
+	if (!pud_present(*pud_k))
+		return NULL;
+
+	pmd_k = pmd_offset(pud_k, address);
+	if (!pmd_present(*pmd_k))
+		return NULL;
+
+	pte_k = pte_offset_kernel(pmd_k, address);
+	entry = *pte_k;
+
+	return pfn_to_kaddr(pte_pfn(entry));
+}
+
+static unsigned long lookup_address(struct trapped_io *tiop,
+				    unsigned long address)
+{
+	struct resource *res;
+	unsigned long vaddr = (unsigned long)tiop->virt_base;
+	unsigned long len;
+	int k;
+
+	for (k = 0; k < tiop->num_resources; k++) {
+		res = tiop->resource + k;
+		len = roundup((res->end - res->start) + 1, PAGE_SIZE);
+		if (address < (vaddr + len))
+			return res->start + (address - vaddr);
+		vaddr += len;
+	}
+	return 0;
+}
+
+static unsigned long long copy_word(unsigned long src_addr, int src_len,
+				    unsigned long dst_addr, int dst_len)
+{
+	unsigned long long tmp = 0;
+
+	switch (src_len) {
+	case 1:
+		tmp = ctrl_inb(src_addr);
+		break;
+	case 2:
+		tmp = ctrl_inw(src_addr);
+		break;
+	case 4:
+		tmp = ctrl_inl(src_addr);
+		break;
+	case 8:
+		tmp = ctrl_inq(src_addr);
+		break;
+	}
+
+	switch (dst_len) {
+	case 1:
+		ctrl_outb(tmp, dst_addr);
+		break;
+	case 2:
+		ctrl_outw(tmp, dst_addr);
+		break;
+	case 4:
+		ctrl_outl(tmp, dst_addr);
+		break;
+	case 8:
+		ctrl_outq(tmp, dst_addr);
+		break;
+	}
+
+	return tmp;
+}
+
+static unsigned long from_device(void *dst, const void *src, unsigned long cnt)
+{
+	struct trapped_io *tiop;
+	unsigned long src_addr = (unsigned long)src;
+	unsigned long long tmp;
+
+	pr_debug("trapped io read 0x%08lx (%ld)\n", src_addr, cnt);
+	tiop = lookup_tiop(src_addr);
+	WARN_ON(!tiop || (tiop->magic != IO_TRAPPED_MAGIC));
+
+	src_addr = lookup_address(tiop, src_addr);
+	if (!src_addr)
+		return cnt;
+
+	tmp = copy_word(src_addr, MAX(cnt, (tiop->minimum_bus_width / 8)),
+			(unsigned long)dst, cnt);
+
+	pr_debug("trapped io read 0x%08lx -> 0x%08llx\n", src_addr, tmp);
+	return 0;
+}
+
+static unsigned long to_device(void *dst, const void *src, unsigned long cnt)
+{
+	struct trapped_io *tiop;
+	unsigned long dst_addr = (unsigned long)dst;
+	unsigned long long tmp;
+
+	pr_debug("trapped io write 0x%08lx (%ld)\n", dst_addr, cnt);
+	tiop = lookup_tiop(dst_addr);
+	WARN_ON(!tiop || (tiop->magic != IO_TRAPPED_MAGIC));
+
+	dst_addr = lookup_address(tiop, dst_addr);
+	if (!dst_addr)
+		return cnt;
+
+	tmp = copy_word((unsigned long)src, cnt,
+			dst_addr, MAX(cnt, (tiop->minimum_bus_width / 8)));
+
+	pr_debug("trapped io write 0x%08lx -> 0x%08llx\n", dst_addr, tmp);
+	return 0;
+}
+
+static struct mem_access trapped_io_access = {
+	from_device,
+	to_device,
+};
+
+int handle_trapped_io(struct pt_regs *regs, unsigned long address)
+{
+	mm_segment_t oldfs;
+	opcode_t instruction;
+	int tmp;
+
+	if (!lookup_tiop(address))
+		return 0;
+
+	WARN_ON(user_mode(regs));
+
+	oldfs = get_fs();
+	set_fs(KERNEL_DS);
+	if (copy_from_user(&instruction, (void *)(regs->pc),
+			   sizeof(instruction))) {
+		set_fs(oldfs);
+		return 0;
+	}
+
+	tmp = handle_unaligned_access(instruction, regs, &trapped_io_access);
+	set_fs(oldfs);
+	return tmp == 0;
+}