[ARM] 4184/1: iop: cp6 access handler (undef_hook)

Enable svc access to cp6 via an undefined instruction hook.  Do not enable
access for usr code.

This patch also makes iop13xx select PLAT_IOP, this requires a small change
to drivers/i2c/busses/i2c-iop3xx.c.

Per Lennert Buytenhek's note, the cp6 trap routine is moved to arch/arm/plat-iop
Per Nicolas Pitre's note, the cp_wait is skipped since the latency to
return to the faulting function is longer than cp_wait.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 50 insertions, 0 deletions

diff --git a/arch/arm/plat-iop/cp6.c b/arch/arm/plat-iop/cp6.c
new file mode 100644
index 000000000000..9612a87e2a88
--- /dev/null
+++ b/arch/arm/plat-iop/cp6.c
@@ -0,0 +1,50 @@
+/*
+ * IOP Coprocessor-6 access handler
+ * Copyright (c) 2006, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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., 59 Temple
+ * Place - Suite 330, Boston, MA 02111-1307 USA.
+ *
+ */
+#include <linux/init.h>
+#include <asm/traps.h>
+
+static int cp6_trap(struct pt_regs *regs, unsigned int instr)
+{
+        u32 temp;
+
+        /* enable cp6 access */
+        asm volatile (
+                "mrc    p15, 0, %0, c15, c1, 0\n\t"
+                "orr    %0, %0, #(1 << 6)\n\t"
+                "mcr    p15, 0, %0, c15, c1, 0\n\t"
+                : "=r"(temp));
+
+        return 0;
+}
+
+/* permit kernel space cp6 access
+ * deny user space cp6 access
+ */
+static struct undef_hook cp6_hook = {
+        .instr_mask     = 0x0f000ff0,
+        .instr_val      = 0x0e000610,
+        .cpsr_mask      = MODE_MASK,
+        .cpsr_val       = SVC_MODE,
+        .fn             = cp6_trap,
+};
+
+void __init iop_init_cp6_handler(void)
+{
+        register_undef_hook(&cp6_hook);
+}