MIPS: Netlogic: COP2 save/restore code

Add COP2 register state structure and functions for Netlogic XLP. The
RX and TX buffers and status registers are to be saved. Since the
registers are 64-bit, do the implementation in inline assembly which
works on both 32-bit and 64-bit kernels.

Signed-off-by: Jayachandran C <jchandra@broadcom.com>
Cc: linux-mips@linux-mips.org
Cc: ddaney.cavm@gmail.com
Patchwork: https://patchwork.linux-mips.org/patch/5413/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

2 files changed, 119 insertions, 1 deletions

diff --git a/arch/mips/netlogic/xlp/Makefile b/arch/mips/netlogic/xlp/Makefile
index a84d6ed3746..e8dd14c38cb 100644
--- a/arch/mips/netlogic/xlp/Makefile
+++ b/arch/mips/netlogic/xlp/Makefile
@@ -1,3 +1,3 @@
-obj-y				+= setup.o nlm_hal.o
+obj-y				+= setup.o nlm_hal.o cop2-ex.o
 obj-$(CONFIG_SMP)		+= wakeup.o
 obj-$(CONFIG_USB)		+= usb-init.o
diff --git a/arch/mips/netlogic/xlp/cop2-ex.c b/arch/mips/netlogic/xlp/cop2-ex.c
new file mode 100644
index 00000000000..52bc5de4200
--- /dev/null
+++ b/arch/mips/netlogic/xlp/cop2-ex.c
@@ -0,0 +1,118 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2013 Broadcom Corporation.
+ *
+ * based on arch/mips/cavium-octeon/cpu.c
+ * Copyright (C) 2009 Wind River Systems,
+ *   written by Ralf Baechle <ralf@linux-mips.org>
+ */
+#include <linux/init.h>
+#include <linux/irqflags.h>
+#include <linux/notifier.h>
+#include <linux/prefetch.h>
+#include <linux/sched.h>
+
+#include <asm/cop2.h>
+#include <asm/current.h>
+#include <asm/mipsregs.h>
+#include <asm/page.h>
+
+#include <asm/netlogic/mips-extns.h>
+
+/*
+ * 64 bit ops are done in inline assembly to support 32 bit
+ * compilation
+ */
+void nlm_cop2_save(struct nlm_cop2_state *r)
+{
+	asm volatile(
+		".set	push\n"
+		".set	noat\n"
+		"dmfc2	$1, $0, 0\n"
+		"sd	$1, 0(%1)\n"
+		"dmfc2	$1, $0, 1\n"
+		"sd	$1, 8(%1)\n"
+		"dmfc2	$1, $0, 2\n"
+		"sd	$1, 16(%1)\n"
+		"dmfc2	$1, $0, 3\n"
+		"sd	$1, 24(%1)\n"
+		"dmfc2	$1, $1, 0\n"
+		"sd	$1, 0(%2)\n"
+		"dmfc2	$1, $1, 1\n"
+		"sd	$1, 8(%2)\n"
+		"dmfc2	$1, $1, 2\n"
+		"sd	$1, 16(%2)\n"
+		"dmfc2	$1, $1, 3\n"
+		"sd	$1, 24(%2)\n"
+		".set	pop\n"
+		: "=m"(*r)
+		: "r"(r->tx), "r"(r->rx));
+
+	r->tx_msg_status = __read_32bit_c2_register($2, 0);
+	r->rx_msg_status = __read_32bit_c2_register($3, 0) & 0x0fffffff;
+}
+
+void nlm_cop2_restore(struct nlm_cop2_state *r)
+{
+	u32 rstat;
+
+	asm volatile(
+		".set	push\n"
+		".set	noat\n"
+		"ld	$1, 0(%1)\n"
+		"dmtc2	$1, $0, 0\n"
+		"ld	$1, 8(%1)\n"
+		"dmtc2	$1, $0, 1\n"
+		"ld	$1, 16(%1)\n"
+		"dmtc2	$1, $0, 2\n"
+		"ld	$1, 24(%1)\n"
+		"dmtc2	$1, $0, 3\n"
+		"ld	$1, 0(%2)\n"
+		"dmtc2	$1, $1, 0\n"
+		"ld	$1, 8(%2)\n"
+		"dmtc2	$1, $1, 1\n"
+		"ld	$1, 16(%2)\n"
+		"dmtc2	$1, $1, 2\n"
+		"ld	$1, 24(%2)\n"
+		"dmtc2	$1, $1, 3\n"
+		".set	pop\n"
+		: : "m"(*r), "r"(r->tx), "r"(r->rx));
+
+	__write_32bit_c2_register($2, 0, r->tx_msg_status);
+	rstat = __read_32bit_c2_register($3, 0) & 0xf0000000u;
+	__write_32bit_c2_register($3, 0, r->rx_msg_status | rstat);
+}
+
+static int nlm_cu2_call(struct notifier_block *nfb, unsigned long action,
+	void *data)
+{
+	unsigned long flags;
+	unsigned int status;
+
+	switch (action) {
+	case CU2_EXCEPTION:
+		if (!capable(CAP_SYS_ADMIN) || !capable(CAP_SYS_RAWIO))
+			break;
+		local_irq_save(flags);
+		KSTK_STATUS(current) |= ST0_CU2;
+		status = read_c0_status();
+		write_c0_status(status | ST0_CU2);
+		nlm_cop2_restore(&(current->thread.cp2));
+		write_c0_status(status & ~ST0_CU2);
+		local_irq_restore(flags);
+		pr_info("COP2 access enabled for pid %d (%s)\n",
+					current->pid, current->comm);
+		return NOTIFY_BAD;	/* Don't call default notifier */
+	}
+
+	return NOTIFY_OK;		/* Let default notifier send signals */
+}
+
+static int __init nlm_cu2_setup(void)
+{
+	return cu2_notifier(nlm_cu2_call, 0);
+}
+early_initcall(nlm_cu2_setup);