ARCv2: don't assume core 0x54 has dual issue
The first release of core4 (0x54) was dual issue only (HS4x).
Newer releases allow hardware to be configured as single issue (HS3x)
or dual issue.
Prevent accessing a HS4x only aux register in HS3x, which otherwise
leads to illegal instruction exceptions
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
diff --git a/arch/arc/include/asm/arcregs.h b/arch/arc/include/asm/arcregs.h
index f1b86ce..a27eafd 100644
--- a/arch/arc/include/asm/arcregs.h
+++ b/arch/arc/include/asm/arcregs.h
@@ -151,6 +151,14 @@
#endif
};
+struct bcr_uarch_build_arcv2 {
+#ifdef CONFIG_CPU_BIG_ENDIAN
+ unsigned int pad:8, prod:8, maj:8, min:8;
+#else
+ unsigned int min:8, maj:8, prod:8, pad:8;
+#endif
+};
+
struct bcr_mpy {
#ifdef CONFIG_CPU_BIG_ENDIAN
unsigned int pad:8, x1616:8, dsp:4, cycles:2, type:2, ver:8;
diff --git a/arch/arc/kernel/setup.c b/arch/arc/kernel/setup.c
index 93d4d66..7b23409 100644
--- a/arch/arc/kernel/setup.c
+++ b/arch/arc/kernel/setup.c
@@ -199,13 +199,29 @@
cpu->bpu.ret_stk = 4 << bpu.rse;
if (cpu->core.family >= 0x54) {
- unsigned int exec_ctrl;
- READ_BCR(AUX_EXEC_CTRL, exec_ctrl);
- cpu->extn.dual_enb = !(exec_ctrl & 1);
+ struct bcr_uarch_build_arcv2 uarch;
- /* dual issue always present for this core */
- cpu->extn.dual = 1;
+ /*
+ * The first 0x54 core (uarch maj:min 0:1 or 0:2) was
+ * dual issue only (HS4x). But next uarch rev (1:0)
+ * allows it be configured for single issue (HS3x)
+ * Ensure we fiddle with dual issue only on HS4x
+ */
+ READ_BCR(ARC_REG_MICRO_ARCH_BCR, uarch);
+
+ if (uarch.prod == 4) {
+ unsigned int exec_ctrl;
+
+ /* dual issue hardware always present */
+ cpu->extn.dual = 1;
+
+ READ_BCR(AUX_EXEC_CTRL, exec_ctrl);
+
+ /* dual issue hardware enabled ? */
+ cpu->extn.dual_enb = !(exec_ctrl & 1);
+
+ }
}
}
