ARM: Add code for a simple bootloader for MP boot.

1 files changed, 71 insertions, 0 deletions

diff --git a/system/arm/simple_bootloader/simple.S b/system/arm/simple_bootloader/simple.S
new file mode 100644
index 000000000..d8f2905e9
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+++ b/system/arm/simple_bootloader/simple.S
@@ -0,0 +1,71 @@
+/*
+ * Copyright (c) 2010 ARM Limited
+ * All rights reserved
+ *
+ * The license below extends only to copyright in the software and shall
+ * not be construed as granting a license to any other intellectual
+ * property including but not limited to intellectual property relating
+ * to a hardware implementation of the functionality of the software
+ * licensed hereunder.  You may use the software subject to the license
+ * terms below provided that you ensure that this notice is replicated
+ * unmodified and in its entirety in all distributions of the software,
+ * modified or unmodified, in source code or in binary form.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met: redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer;
+ * redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution;
+ * neither the name of the copyright holders nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Authors: Ali Saidi
+ */
+
+/*************************************************************************
+ * Super simple bootloader
+ * Preserve loaded values that we need to pass to the kernel (r0, r1, r2)
+ * Additionally M5 puts the kernel start address in r3
+ *
+ * Upon executing this code:
+ * r0 = 0, r1 = machine number, r2 = atags ptr
+ * r3 = kernel start address
+ *
+ * CPU 0 should branch to the kernel start address and it's done with
+ * the boot loader. Other CPUs need to start in a wfi loop. When CPU0 sends
+ * an IPI the slave CPUs reads a register which CPU0 has programmed with the
+ * boot address for the secondary cpu
+ **************************************************************************/
+.text
+.globl  _start
+.extern	main
+_start:
+_entry:
+    mrc p15, 0, r4, c0, c0, 5 // get the MPIDR register
+    uxtb r4, r4               // isolate the lower 8 bits (affinity lvl 1)
+    adds r4, r4, #0           // set flags for branch
+    bxeq r3                   // if it's 0 (CPU 0), branch to kernel
+pen:
+    wfi                       // otherwise wait for an interrupt
+    mov r4, #0x30             // Build address of the system controller
+    movt r4, #0x1000          // flag register r4 =  0x10000030
+    ldr r5, [r4]              // load the value
+    movs r5, r5               // set the flags on this value
+    beq pen                   // if it's zero try again
+    bx r5                     // Jump to where we've been told
+    bkpt                      // We should never get here