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authorJiaxun Yang <jiaxun.yang@flygoat.com>2020-01-13 18:16:11 +0800
committerPaul Burton <paulburton@kernel.org>2020-01-22 15:56:08 -0800
commitece276de2a1f90b6a7836d388c372b9025345469 (patch)
tree7a1a50ccc9502f153efd87015a51a2c8fdb9b961 /arch/mips/kernel
parent0a3d5b577784e93ae1b21aff4c1f150eca25813a (diff)
downloadlinux-ece276de2a1f90b6a7836d388c372b9025345469.tar.bz2
MIPS: Add MAC2008 Support
MAC2008 means the processor implemented IEEE754 style Fused MADD instruction. It was introduced in Release3 but removed in Release5. The toolchain support of MAC2008 have never landed except for Loongson processors. This patch aimed to disabled the MAC2008 if it's optional. For MAC2008 only processors, we corrected math-emu behavior to align with actual hardware behavior. Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com> [paulburton@kernel.org: Fixup MIPSr2-r5 check in cpu_set_fpu_2008.] Signed-off-by: Paul Burton <paulburton@kernel.org> Cc: linux-mips@vger.kernel.org Cc: chenhc@lemote.com Cc: paul.burton@mips.com Cc: linux-kernel@vger.kernel.org
Diffstat (limited to 'arch/mips/kernel')
-rw-r--r--arch/mips/kernel/cpu-probe.c16
1 files changed, 15 insertions, 1 deletions
diff --git a/arch/mips/kernel/cpu-probe.c b/arch/mips/kernel/cpu-probe.c
index c06365404a8e..6ab6b03d35ba 100644
--- a/arch/mips/kernel/cpu-probe.c
+++ b/arch/mips/kernel/cpu-probe.c
@@ -102,7 +102,12 @@ static void cpu_set_fpu_2008(struct cpuinfo_mips *c)
if (fir & MIPS_FPIR_HAS2008) {
fcsr = read_32bit_cp1_register(CP1_STATUS);
- fcsr0 = fcsr & ~(FPU_CSR_ABS2008 | FPU_CSR_NAN2008);
+ /*
+ * MAC2008 toolchain never landed in real world, so we're only
+ * testing wether it can be disabled and don't try to enabled
+ * it.
+ */
+ fcsr0 = fcsr & ~(FPU_CSR_ABS2008 | FPU_CSR_NAN2008 | FPU_CSR_MAC2008);
write_32bit_cp1_register(CP1_STATUS, fcsr0);
fcsr0 = read_32bit_cp1_register(CP1_STATUS);
@@ -112,6 +117,15 @@ static void cpu_set_fpu_2008(struct cpuinfo_mips *c)
write_32bit_cp1_register(CP1_STATUS, fcsr);
+ if (c->isa_level & (MIPS_CPU_ISA_M32R2 | MIPS_CPU_ISA_M64R2)) {
+ /*
+ * The bit for MAC2008 might be reused by R6 in future,
+ * so we only test for R2-R5.
+ */
+ if (fcsr0 & FPU_CSR_MAC2008)
+ c->options |= MIPS_CPU_MAC_2008_ONLY;
+ }
+
if (!(fcsr0 & FPU_CSR_NAN2008))
c->options |= MIPS_CPU_NAN_LEGACY;
if (fcsr1 & FPU_CSR_NAN2008)