Merge Qualcom Hexagon architecture

This is the fifth version of the patchset (with one tiny whitespace fix)
to the Linux kernel to support the Qualcomm Hexagon architecture.

Between now and the next pull requests, Richard Kuo should have his key
signed, etc., and should be back on kernel.org.  In the meantime, this
got merged as a emailed patch-series.

* Hexagon: (36 commits)
  Add extra arch overrides to asm-generic/checksum.h
  Hexagon: Add self to MAINTAINERS
  Hexagon: Add basic stacktrace functionality for Hexagon architecture.
  Hexagon: Add configuration and makefiles for the Hexagon architecture.
  Hexagon: Comet platform support
  Hexagon: kgdb support files
  Hexagon: Add page-fault support.
  Hexagon: Add page table header files & etc.
  Hexagon: Add ioremap support
  Hexagon: Provide DMA implementation
  Hexagon: Implement basic TLB management routines for Hexagon.
  Hexagon: Implement basic cache-flush support
  Hexagon: Provide basic implementation and/or stubs for I/O routines.
  Hexagon: Add user access functions
  Hexagon: Add locking types and functions
  Hexagon: Add SMP support
  Hexagon: Provide basic debugging and system trap support.
  Hexagon: Add ptrace support
  Hexagon: Add time and timer functions
  Hexagon: Add interrupts
  ...

1 files changed, 116 insertions, 0 deletions

diff --git a/arch/hexagon/include/asm/uaccess.h b/arch/hexagon/include/asm/uaccess.h
new file mode 100644
index 0000000..7e706ea
--- /dev/null
+++ b/arch/hexagon/include/asm/uaccess.h
@@ -0,0 +1,116 @@
+/*
+ * User memory access support for Hexagon
+ *
+ * Copyright (c) 2010-2011, Code Aurora Forum. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * 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., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+#ifndef _ASM_UACCESS_H
+#define _ASM_UACCESS_H
+/*
+ * User space memory access functions
+ */
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <asm/segment.h>
+#include <asm/sections.h>
+
+/*
+ * access_ok: - Checks if a user space pointer is valid
+ * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE.  Note that
+ *        %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe
+ *        to write to a block, it is always safe to read from it.
+ * @addr: User space pointer to start of block to check
+ * @size: Size of block to check
+ *
+ * Context: User context only.  This function may sleep.
+ *
+ * Checks if a pointer to a block of memory in user space is valid.
+ *
+ * Returns true (nonzero) if the memory block *may* be valid, false (zero)
+ * if it is definitely invalid.
+ *
+ * User address space in Hexagon, like x86, goes to 0xbfffffff, so the
+ * simple MSB-based tests used by MIPS won't work.  Some further
+ * optimization is probably possible here, but for now, keep it
+ * reasonably simple and not *too* slow.  After all, we've got the
+ * MMU for backup.
+ */
+#define VERIFY_READ     0
+#define VERIFY_WRITE    1
+
+#define __access_ok(addr, size) \
+	((get_fs().seg == KERNEL_DS.seg) || \
+	(((unsigned long)addr < get_fs().seg) && \
+	  (unsigned long)size < (get_fs().seg - (unsigned long)addr)))
+
+/*
+ * When a kernel-mode page fault is taken, the faulting instruction
+ * address is checked against a table of exception_table_entries.
+ * Each entry is a tuple of the address of an instruction that may
+ * be authorized to fault, and the address at which execution should
+ * be resumed instead of the faulting instruction, so as to effect
+ * a workaround.
+ */
+
+/*  Assembly somewhat optimized copy routines  */
+unsigned long __copy_from_user_hexagon(void *to, const void __user *from,
+				     unsigned long n);
+unsigned long __copy_to_user_hexagon(void __user *to, const void *from,
+				   unsigned long n);
+
+#define __copy_from_user(to, from, n) __copy_from_user_hexagon(to, from, n)
+#define __copy_to_user(to, from, n) __copy_to_user_hexagon(to, from, n)
+
+/*
+ * XXX todo: some additonal performance gain is possible by
+ * implementing __copy_to/from_user_inatomic, which is much
+ * like __copy_to/from_user, but performs slightly less checking.
+ */
+
+__kernel_size_t __clear_user_hexagon(void __user *dest, unsigned long count);
+#define __clear_user(a, s) __clear_user_hexagon((a), (s))
+
+#define __strncpy_from_user(dst, src, n) hexagon_strncpy_from_user(dst, src, n)
+
+/*  get around the ifndef in asm-generic/uaccess.h  */
+#define __strnlen_user __strnlen_user
+
+extern long __strnlen_user(const char __user *src, long n);
+
+static inline long hexagon_strncpy_from_user(char *dst, const char __user *src,
+					     long n);
+
+#include <asm-generic/uaccess.h>
+
+/*  Todo:  an actual accelerated version of this.  */
+static inline long hexagon_strncpy_from_user(char *dst, const char __user *src,
+					     long n)
+{
+	long res = __strnlen_user(src, n);
+
+	/* return from strnlen can't be zero -- that would be rubbish. */
+
+	if (res > n) {
+		copy_from_user(dst, src, n);
+		return n;
+	} else {
+		copy_from_user(dst, src, res);
+		return res-1;
+	}
+}
+
+#endif