perf: RISC-V: Add support for SBI PMU and Sscofpmf

This series improves perf support for RISC-V based system using SBI PMU
and Sscofpmf extensions, by adding a new generic RISC-V perf framework
along with a pair of drivers: one that usese the new
performance-monitoring extensions and one that keeps support for the
existing systems that only have the legacy counters.

Tested-by: Nikita Shubin <n.shubin@yadro.com>

* palmer/riscv-pmu:
  MAINTAINERS: Add entry for RISC-V PMU drivers
  Documentation: riscv: Remove the old documentation
  RISC-V: Add sscofpmf extension support
  RISC-V: Add perf platform driver based on SBI PMU extension
  RISC-V: Add RISC-V SBI PMU extension definitions
  RISC-V: Add a simple platform driver for RISC-V legacy perf
  RISC-V: Add a perf core library for pmu drivers
  RISC-V: Add CSR encodings for all HPMCOUNTERS
  RISC-V: Remove the current perf implementation

2 files changed, 76 insertions, 0 deletions

diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 411a428ace4d..51c7e4929df7 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -165,6 +165,7 @@ enum cpuhp_state {
 	CPUHP_AP_PERF_ARM_HW_BREAKPOINT_STARTING,
 	CPUHP_AP_PERF_ARM_ACPI_STARTING,
 	CPUHP_AP_PERF_ARM_STARTING,
+	CPUHP_AP_PERF_RISCV_STARTING,
 	CPUHP_AP_ARM_L2X0_STARTING,
 	CPUHP_AP_EXYNOS4_MCT_TIMER_STARTING,
 	CPUHP_AP_ARM_ARCH_TIMER_STARTING,
diff --git a/include/linux/perf/riscv_pmu.h b/include/linux/perf/riscv_pmu.h
new file mode 100644
index 000000000000..46f9b6fe306e
--- /dev/null
+++ b/include/linux/perf/riscv_pmu.h
@@ -0,0 +1,75 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2018 SiFive
+ * Copyright (C) 2018 Andes Technology Corporation
+ * Copyright (C) 2021 Western Digital Corporation or its affiliates.
+ *
+ */
+
+#ifndef _ASM_RISCV_PERF_EVENT_H
+#define _ASM_RISCV_PERF_EVENT_H
+
+#include <linux/perf_event.h>
+#include <linux/ptrace.h>
+#include <linux/interrupt.h>
+
+#ifdef CONFIG_RISCV_PMU
+
+/*
+ * The RISCV_MAX_COUNTERS parameter should be specified.
+ */
+
+#define RISCV_MAX_COUNTERS	64
+#define RISCV_OP_UNSUPP		(-EOPNOTSUPP)
+#define RISCV_PMU_PDEV_NAME	"riscv-pmu"
+#define RISCV_PMU_LEGACY_PDEV_NAME	"riscv-pmu-legacy"
+
+#define RISCV_PMU_STOP_FLAG_RESET 1
+
+struct cpu_hw_events {
+	/* currently enabled events */
+	int			n_events;
+	/* Counter overflow interrupt */
+	int		irq;
+	/* currently enabled events */
+	struct perf_event	*events[RISCV_MAX_COUNTERS];
+	/* currently enabled hardware counters */
+	DECLARE_BITMAP(used_hw_ctrs, RISCV_MAX_COUNTERS);
+	/* currently enabled firmware counters */
+	DECLARE_BITMAP(used_fw_ctrs, RISCV_MAX_COUNTERS);
+};
+
+struct riscv_pmu {
+	struct pmu	pmu;
+	char		*name;
+
+	irqreturn_t	(*handle_irq)(int irq_num, void *dev);
+
+	int		num_counters;
+	u64		(*ctr_read)(struct perf_event *event);
+	int		(*ctr_get_idx)(struct perf_event *event);
+	int		(*ctr_get_width)(int idx);
+	void		(*ctr_clear_idx)(struct perf_event *event);
+	void		(*ctr_start)(struct perf_event *event, u64 init_val);
+	void		(*ctr_stop)(struct perf_event *event, unsigned long flag);
+	int		(*event_map)(struct perf_event *event, u64 *config);
+
+	struct cpu_hw_events	__percpu *hw_events;
+	struct hlist_node	node;
+};
+
+#define to_riscv_pmu(p) (container_of(p, struct riscv_pmu, pmu))
+unsigned long riscv_pmu_ctr_read_csr(unsigned long csr);
+int riscv_pmu_event_set_period(struct perf_event *event);
+uint64_t riscv_pmu_ctr_get_width_mask(struct perf_event *event);
+u64 riscv_pmu_event_update(struct perf_event *event);
+#ifdef CONFIG_RISCV_PMU_LEGACY
+void riscv_pmu_legacy_skip_init(void);
+#else
+static inline void riscv_pmu_legacy_skip_init(void) {};
+#endif
+struct riscv_pmu *riscv_pmu_alloc(void);
+
+#endif /* CONFIG_RISCV_PMU */
+
+#endif /* _ASM_RISCV_PERF_EVENT_H */