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, 279 insertions, 0 deletions

diff --git a/arch/hexagon/kernel/process.c b/arch/hexagon/kernel/process.c
new file mode 100644
index 0000000..18c4f0b
--- /dev/null
+++ b/arch/hexagon/kernel/process.c
@@ -0,0 +1,279 @@
+/*
+ * Process creation 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.
+ */
+
+#include <linux/sched.h>
+#include <linux/types.h>
+#include <linux/module.h>
+#include <linux/tick.h>
+#include <linux/uaccess.h>
+#include <linux/slab.h>
+
+/*
+ * Kernel thread creation.  The desired kernel function is "wrapped"
+ * in the kernel_thread_helper function, which does cleanup
+ * afterwards.
+ */
+static void __noreturn kernel_thread_helper(void *arg, int (*fn)(void *))
+{
+	do_exit(fn(arg));
+}
+
+int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
+{
+	struct pt_regs regs;
+
+	memset(&regs, 0, sizeof(regs));
+	/*
+	 * Yes, we're exploting illicit knowledge of the ABI here.
+	 */
+	regs.r00 = (unsigned long) arg;
+	regs.r01 = (unsigned long) fn;
+	pt_set_elr(&regs, (unsigned long)kernel_thread_helper);
+	pt_set_kmode(&regs);
+
+	return do_fork(flags|CLONE_VM|CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
+}
+EXPORT_SYMBOL(kernel_thread);
+
+/*
+ * Program thread launch.  Often defined as a macro in processor.h,
+ * but we're shooting for a small footprint and it's not an inner-loop
+ * performance-critical operation.
+ *
+ * The Hexagon ABI specifies that R28 is zero'ed before program launch,
+ * so that gets automatically done here.  If we ever stop doing that here,
+ * we'll probably want to define the ELF_PLAT_INIT macro.
+ */
+void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp)
+{
+	/* Set to run with user-mode data segmentation */
+	set_fs(USER_DS);
+	/* We want to zero all data-containing registers. Is this overkill? */
+	memset(regs, 0, sizeof(*regs));
+	/* We might want to also zero all Processor registers here */
+	pt_set_usermode(regs);
+	pt_set_elr(regs, pc);
+	pt_set_rte_sp(regs, sp);
+}
+
+/*
+ *  Spin, or better still, do a hardware or VM wait instruction
+ *  If hardware or VM offer wait termination even though interrupts
+ *  are disabled.
+ */
+static void default_idle(void)
+{
+	__vmwait();
+}
+
+void (*idle_sleep)(void) = default_idle;
+
+void cpu_idle(void)
+{
+	while (1) {
+		tick_nohz_stop_sched_tick(1);
+		local_irq_disable();
+		while (!need_resched()) {
+			idle_sleep();
+			/*  interrupts wake us up, but aren't serviced  */
+			local_irq_enable();	/* service interrupt   */
+			local_irq_disable();
+		}
+		local_irq_enable();
+		tick_nohz_restart_sched_tick();
+		schedule();
+	}
+}
+
+/*
+ *  Return saved PC of a blocked thread
+ */
+unsigned long thread_saved_pc(struct task_struct *tsk)
+{
+	return 0;
+}
+
+/*
+ * Copy architecture-specific thread state
+ */
+int copy_thread(unsigned long clone_flags, unsigned long usp,
+		unsigned long unused, struct task_struct *p,
+		struct pt_regs *regs)
+{
+	struct thread_info *ti = task_thread_info(p);
+	struct hexagon_switch_stack *ss;
+	struct pt_regs *childregs;
+	asmlinkage void ret_from_fork(void);
+
+	childregs = (struct pt_regs *) (((unsigned long) ti + THREAD_SIZE) -
+					sizeof(*childregs));
+
+	memcpy(childregs, regs, sizeof(*childregs));
+	ti->regs = childregs;
+
+	/*
+	 * Establish kernel stack pointer and initial PC for new thread
+	 */
+	ss = (struct hexagon_switch_stack *) ((unsigned long) childregs -
+						    sizeof(*ss));
+	ss->lr = (unsigned long)ret_from_fork;
+	p->thread.switch_sp = ss;
+
+	/* If User mode thread, set pt_reg stack pointer as per parameter */
+	if (user_mode(childregs)) {
+		pt_set_rte_sp(childregs, usp);
+
+		/* Child sees zero return value */
+		childregs->r00 = 0;
+
+		/*
+		 * The clone syscall has the C signature:
+		 * int [r0] clone(int flags [r0],
+		 *           void *child_frame [r1],
+		 *           void *parent_tid [r2],
+		 *           void *child_tid [r3],
+		 *           void *thread_control_block [r4]);
+		 * ugp is used to provide TLS support.
+		 */
+		if (clone_flags & CLONE_SETTLS)
+			childregs->ugp = childregs->r04;
+
+		/*
+		 * Parent sees new pid -- not necessary, not even possible at
+		 * this point in the fork process
+		 * Might also want to set things like ti->addr_limit
+		 */
+	} else {
+		/*
+		 * If kernel thread, resume stack is kernel stack base.
+		 * Note that this is pointer arithmetic on pt_regs *
+		 */
+		pt_set_rte_sp(childregs, (unsigned long)(childregs + 1));
+		/*
+		 * We need the current thread_info fast path pointer
+		 * set up in pt_regs.  The register to be used is
+		 * parametric for assembler code, but the mechanism
+		 * doesn't drop neatly into C.  Needs to be fixed.
+		 */
+		childregs->THREADINFO_REG = (unsigned long) ti;
+	}
+
+	/*
+	 * thread_info pointer is pulled out of task_struct "stack"
+	 * field on switch_to.
+	 */
+	p->stack = (void *)ti;
+
+	return 0;
+}
+
+/*
+ * Release any architecture-specific resources locked by thread
+ */
+void release_thread(struct task_struct *dead_task)
+{
+}
+
+/*
+ * Free any architecture-specific thread data structures, etc.
+ */
+void exit_thread(void)
+{
+}
+
+/*
+ * Some archs flush debug and FPU info here
+ */
+void flush_thread(void)
+{
+}
+
+/*
+ * The "wait channel" terminology is archaic, but what we want
+ * is an identification of the point at which the scheduler
+ * was invoked by a blocked thread.
+ */
+unsigned long get_wchan(struct task_struct *p)
+{
+	unsigned long fp, pc;
+	unsigned long stack_page;
+	int count = 0;
+	if (!p || p == current || p->state == TASK_RUNNING)
+		return 0;
+
+	stack_page = (unsigned long)task_stack_page(p);
+	fp = ((struct hexagon_switch_stack *)p->thread.switch_sp)->fp;
+	do {
+		if (fp < (stack_page + sizeof(struct thread_info)) ||
+			fp >= (THREAD_SIZE - 8 + stack_page))
+			return 0;
+		pc = ((unsigned long *)fp)[1];
+		if (!in_sched_functions(pc))
+			return pc;
+		fp = *(unsigned long *) fp;
+	} while (count++ < 16);
+
+	return 0;
+}
+
+/*
+ * Borrowed from PowerPC -- basically allow smaller kernel stacks if we
+ * go crazy with the page sizes.
+ */
+#if THREAD_SHIFT < PAGE_SHIFT
+
+static struct kmem_cache *thread_info_cache;
+
+struct thread_info *alloc_thread_info_node(struct task_struct *tsk, int node)
+{
+	struct thread_info *ti;
+
+	ti = kmem_cache_alloc_node(thread_info_cache, GFP_KERNEL, node);
+	if (unlikely(ti == NULL))
+		return NULL;
+#ifdef CONFIG_DEBUG_STACK_USAGE
+	memset(ti, 0, THREAD_SIZE);
+#endif
+	return ti;
+}
+
+void free_thread_info(struct thread_info *ti)
+{
+	kmem_cache_free(thread_info_cache, ti);
+}
+
+/*  Weak symbol; called by init/main.c  */
+
+void thread_info_cache_init(void)
+{
+	thread_info_cache = kmem_cache_create("thread_info", THREAD_SIZE,
+					      THREAD_SIZE, 0, NULL);
+	BUG_ON(thread_info_cache == NULL);
+}
+
+#endif /* THREAD_SHIFT < PAGE_SHIFT */
+
+/*
+ * Required placeholder.
+ */
+int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
+{
+	return 0;
+}