C6X: early boot code

Original port to early 2.6 kernel using TI COFF toolchain.
Brought up to date by Mark Salter <msalter@redhat.com>

This patch provides the early boot code for C6X architecture. There is a
16 entry vector table which is used to direct reset and interrupt events. The
vector table entries contain a small amount of code (maximum of 8 opcodes)
which simply branches to the actual event handling code.

The head.S code simply clears BSS, setups up a few control registers, and calls
machine_init followed by start_kernel. The machine_init code in setup.c does
the early flat tree parsing (memory, commandline, etc). At setup_arch time, the
code does the usual memory setup and minimally scans the devicetree for any
needed information.

Signed-off-by: Aurelien Jacquiot <a-jacquiot@ti.com>
Signed-off-by: Mark Salter <msalter@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>

1 files changed, 84 insertions, 0 deletions

diff --git a/arch/c6x/kernel/head.S b/arch/c6x/kernel/head.S
new file mode 100644
index 000000000000..133eab6edf6b
--- /dev/null
+++ b/arch/c6x/kernel/head.S
@@ -0,0 +1,84 @@
+;
+;  Port on Texas Instruments TMS320C6x architecture
+;
+;  Copyright (C) 2004, 2009, 2010, 2011 Texas Instruments Incorporated
+;  Author: Aurelien Jacquiot (aurelien.jacquiot@jaluna.com)
+;
+;  This program is free software; you can redistribute it and/or modify
+;  it under the terms of the GNU General Public License version 2 as
+;  published by the Free Software Foundation.
+;
+#include <linux/linkage.h>
+#include <linux/of_fdt.h>
+#include <asm/asm-offsets.h>
+
+        __HEAD
+ENTRY(_c_int00)
+        ;; Save magic and pointer
+        MV      .S1     A4,A10
+        MV      .S2     B4,B10
+        MVKL    .S2     __bss_start,B5
+        MVKH    .S2     __bss_start,B5
+        MVKL    .S2     __bss_stop,B6
+        MVKH    .S2     __bss_stop,B6
+        SUB     .L2     B6,B5,B6 ; bss size
+
+        ;; Set the stack pointer
+        MVKL    .S2     current_ksp,B0
+        MVKH    .S2     current_ksp,B0
+        LDW     .D2T2   *B0,B15
+
+        ;; clear bss
+        SHR     .S2     B6,3,B0   ; number of dwords to clear
+        ZERO    .L2     B13
+        ZERO    .L2     B12
+bss_loop:
+        BDEC    .S2     bss_loop,B0
+        NOP     3
+        CMPLT   .L2     B0,0,B1
+ [!B1]  STDW    .D2T2   B13:B12,*B5++[1]
+
+        NOP     4
+        AND     .D2     ~7,B15,B15
+
+        ;; Clear GIE and PGIE
+        MVC     .S2     CSR,B2
+        CLR     .S2     B2,0,1,B2
+        MVC     .S2     B2,CSR
+        MVC     .S2     TSR,B2
+        CLR     .S2     B2,0,1,B2
+        MVC     .S2     B2,TSR
+        MVC     .S2     ITSR,B2
+        CLR     .S2     B2,0,1,B2
+        MVC     .S2     B2,ITSR
+        MVC     .S2     NTSR,B2
+        CLR     .S2     B2,0,1,B2
+        MVC     .S2     B2,NTSR
+
+        ;; pass DTB pointer to machine_init (or zero if none)
+        MVKL    .S1     OF_DT_HEADER,A0
+        MVKH    .S1     OF_DT_HEADER,A0
+        CMPEQ   .L1     A10,A0,A0
+  [A0]  MV      .S1X    B10,A4
+  [!A0] MVK     .S1     0,A4
+
+#ifdef CONFIG_C6X_BIG_KERNEL
+        MVKL    .S1     machine_init,A0
+        MVKH    .S1     machine_init,A0
+        B       .S2X    A0
+        ADDKPC  .S2     0f,B3,4
+0:
+#else
+        CALLP   .S2     machine_init,B3
+#endif
+
+        ;; Jump to Linux init
+#ifdef CONFIG_C6X_BIG_KERNEL
+        MVKL    .S1     start_kernel,A0
+        MVKH    .S1     start_kernel,A0
+        B       .S2X    A0
+#else
+        B       .S2     start_kernel
+#endif
+        NOP     5
+L1:     BNOP    .S2     L1,5