Merge tag 'mips_fixes_4.15_2' of git://git.kernel.org/pub/scm/linux/kernel/git/jhogan/mips

Pull MIPS fixes from James Hogan:
 "Some final MIPS fixes for 4.15, including important build fixes and a
  MAINTAINERS update:

   - Add myself as MIPS co-maintainer.

   - Fix various all*config build failures (particularly as a result of
     switching the default MIPS platform to the "generic" platform).

   - Fix GCC7 build failures (duplicate const and questionable calls to
     missing __multi3 intrinsic on mips64r6).

   - Fix warnings when CPU Idle is enabled (4.14).

   - Fix AR7 serial output (since 3.17).

   - Fix ralink platform_get_irq error checking (since 3.12)"

* tag 'mips_fixes_4.15_2' of git://git.kernel.org/pub/scm/linux/kernel/git/jhogan/mips:
  MAINTAINERS: Add James as MIPS co-maintainer
  MIPS: Fix undefined reference to physical_memsize
  MIPS: Implement __multi3 for GCC7 MIPS64r6 builds
  MIPS: mm: Fix duplicate "const" on insn_table_MM
  MIPS: CM: Drop WARN_ON(vp != 0)
  MIPS: ralink: Fix platform_get_irq's error checking
  MIPS: Fix CPS SMP NS16550 UART defaults
  MIPS: BCM47XX Avoid compile error with MIPS allnoconfig
  MIPS: RB532: Avoid undefined mac_pton without GENERIC_NET_UTILS
  MIPS: RB532: Avoid undefined early_serial_setup() without SERIAL_8250_CONSOLE
  MIPS: ath25: Avoid undefined early_serial_setup() without SERIAL_8250_CONSOLE
  MIPS: AR7: ensure the port type's FCR value is used

1 files changed, 54 insertions, 0 deletions

diff --git a/arch/mips/lib/multi3.c b/arch/mips/lib/multi3.c
new file mode 100644
index 000000000000..111ad475aa0c
--- /dev/null
+++ b/arch/mips/lib/multi3.c
@@ -0,0 +1,54 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/export.h>
+
+#include "libgcc.h"
+
+/*
+ * GCC 7 suboptimally generates __multi3 calls for mips64r6, so for that
+ * specific case only we'll implement it here.
+ *
+ * See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82981
+ */
+#if defined(CONFIG_64BIT) && defined(CONFIG_CPU_MIPSR6) && (__GNUC__ == 7)
+
+/* multiply 64-bit values, low 64-bits returned */
+static inline long long notrace dmulu(long long a, long long b)
+{
+	long long res;
+
+	asm ("dmulu %0,%1,%2" : "=r" (res) : "r" (a), "r" (b));
+	return res;
+}
+
+/* multiply 64-bit unsigned values, high 64-bits of 128-bit result returned */
+static inline long long notrace dmuhu(long long a, long long b)
+{
+	long long res;
+
+	asm ("dmuhu %0,%1,%2" : "=r" (res) : "r" (a), "r" (b));
+	return res;
+}
+
+/* multiply 128-bit values, low 128-bits returned */
+ti_type notrace __multi3(ti_type a, ti_type b)
+{
+	TWunion res, aa, bb;
+
+	aa.ti = a;
+	bb.ti = b;
+
+	/*
+	 * a * b =           (a.lo * b.lo)
+	 *         + 2^64  * (a.hi * b.lo + a.lo * b.hi)
+	 *        [+ 2^128 * (a.hi * b.hi)]
+	 */
+	res.s.low = dmulu(aa.s.low, bb.s.low);
+	res.s.high = dmuhu(aa.s.low, bb.s.low);
+	res.s.high += dmulu(aa.s.high, bb.s.low);
+	res.s.high += dmulu(aa.s.low, bb.s.high);
+
+	return res.ti;
+}
+EXPORT_SYMBOL(__multi3);
+
+#endif /* 64BIT && CPU_MIPSR6 && GCC7 */