arch/arm/armv7/thread.c: Remove stale file

This file is never built. Plus, `CONFIG_STACK_BOTTOM` does not exist.

Change-Id: I111b20e3443dca701ee8666d44261a00a161d83f
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/50909
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
diff --git a/src/arch/arm/armv7/thread.c b/src/arch/arm/armv7/thread.c
deleted file mode 100644
index 63ef7a8..0000000
--- a/src/arch/arm/armv7/thread.c
+++ /dev/null
@@ -1,110 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-only */
-
-#include <thread.h>
-
-/* The stack frame looks like the following. */
-struct pushed_regs {
-	u32 r4;
-	u32 r5;
-	u32 r6;
-	u32 r7;
-	u32 r8;
-	u32 r9;
-	u32 r10;
-	u32 r11;
-	u32 lr;
-};
-
-static inline uintptr_t push_stack(uintptr_t cur_stack, uintptr_t value)
-{
-	uintptr_t *addr;
-
-	cur_stack -= sizeof(value);
-	addr = (uintptr_t *)cur_stack;
-	*addr = value;
-	return cur_stack;
-}
-
-void arch_prepare_thread(struct thread *t,
-			 void asmlinkage(*thread_entry)(void *), void *arg)
-{
-	uintptr_t stack = t->stack_current;
-	int i;
-	uintptr_t poison = 0xdeadbeef;
-
-	/* Push the LR. thread_entry()
-	 * is assumed to never return.
-	 */
-	stack = push_stack(stack, (uintptr_t)thread_entry);
-	/* Make room for the registers.
-	 * Poison the initial stack. This is good hygiene and finds bugs.
-	 * Poisoning the stack with different values helps when you're
-	 * hunting for (e.g.) misaligned stacks or other such
-	 * weirdness. The -1 is because we already pushed lr.
-	 */
-	for (i = 0; i < sizeof(struct pushed_regs) / sizeof(u32) - 1; i++)
-		stack = push_stack(stack, poison++);
-
-	t->stack_current = stack;
-}
-
-/* We could write this as a .S and the first time around that's how we
- * did it. But there's always the question of matching our ARM
- * directives in the .S with how gcc is doing things.  It seems best
- * to follow the pattern of the rest of the ARM port and just use
- * inline assembly and let gcc get all the ELF magic right.
- */
-void __attribute__((naked))
-switch_to_thread(uintptr_t new_stack, uintptr_t *saved_stack)
-{
-	/* Definitions for those of us not totally familiar with ARM:
-	 * R15 -- PC, R14 -- LR, R13 -- SP
-	 * R0-R3 need not be saved, nor R12.
-	 * on entry, the only saved state is in LR -- the old PC.
-	 * The args are in R0,R1.
-	 * R0 is the new stack
-	 * R1 is a pointer to the old stack save location
-	 * Push R4-R11 and LR
-	 * then switch stacks
-	 * then pop R0-R12 and LR
-	 * then mov PC,LR
-	 *
-	 * stack layout
-	 * +------------+
-	 * |    LR      | <-- sp + 0x20
-	 * +------------+
-	 * |    R11     | <-- sp + 0x1c
-	 * +------------+
-	 * |    R10     | <-- sp + 0x18
-	 * +------------+
-	 * |    R9      | <-- sp + 0x14
-	 * +------------+
-	 * |    R8      | <-- sp + 0x10
-	 * +------------+
-	 * |    R7      | <-- sp + 0x0c
-	 * +------------+
-	 * |    R6      | <-- sp + 0x08
-	 * +------------+
-	 * |    R5      | <-- sp + 0x04
-	 * +------------+
-	 * |    R4      | <-- sp + 0x00
-	 * +------------+
-	 */
-	asm volatile (
-	/* save context. */
-	"push {r4-r11,lr}\n\t"
-	/* Save the current stack */
-	"str sp,[r1]\n\t"
-	/* switch to the new stack */
-	"mov sp,r0\n\t"
-	/* restore the registers */
-	"pop {r4-r11,lr}\n\t"
-	/* resume other thread. */
-	"mov pc,lr\n\t"
-	);
-}
-
-void *arch_get_thread_stackbase(void)
-{
-	return (void *)CONFIG_STACK_BOTTOM;
-}