riscv: perf: RISCV_BASE_PMU should be independent

Selecting PERF_EVENTS without selecting RISCV_BASE_PMU results in a build
error.

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
[Palmer: commit text]
Fixes: 178e9fc47aae("perf: riscv: preliminary RISC-V support")
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

arch/riscv/include/asm/perf_event.h

@@ -12,19 +12,14 @@
 #include <linux/ptrace.h>
 #include <linux/interrupt.h>
 
+#ifdef CONFIG_RISCV_BASE_PMU
 #define RISCV_BASE_COUNTERS	2
 
 /*
  * The RISCV_MAX_COUNTERS parameter should be specified.
  */
 
-#ifdef CONFIG_RISCV_BASE_PMU
 #define RISCV_MAX_COUNTERS	2
-#endif
-
-#ifndef RISCV_MAX_COUNTERS
-#error "Please provide a valid RISCV_MAX_COUNTERS for the PMU."
-#endif
 
 /*
  * These are the indexes of bits in counteren register *minus* 1,
@@ -82,6 +77,7 @@ struct riscv_pmu {
 	int		irq;
 };
 
+#endif
 #ifdef CONFIG_PERF_EVENTS
 #define perf_arch_bpf_user_pt_regs(regs) (struct user_regs_struct *)regs
 #endif

arch/riscv/kernel/Makefile

@@ -43,7 +43,7 @@ obj-$(CONFIG_MODULE_SECTIONS)	+= module-sections.o
 obj-$(CONFIG_FUNCTION_TRACER)	+= mcount.o ftrace.o
 obj-$(CONFIG_DYNAMIC_FTRACE)	+= mcount-dyn.o
 
-obj-$(CONFIG_PERF_EVENTS)	+= perf_event.o
+obj-$(CONFIG_RISCV_BASE_PMU)	+= perf_event.o
 obj-$(CONFIG_PERF_EVENTS)	+= perf_callchain.o
 obj-$(CONFIG_HAVE_PERF_REGS)	+= perf_regs.o
 obj-$(CONFIG_RISCV_SBI)		+= sbi.o