lib: sbi: Introduce the SBI debug triggers extension support

RISC-V Debug specification includes Sdtrig ISA extension
which describes Trigger Module. Triggers can cause
a breakpoint exception or trace action without execution
of a special instruction. They can be used to implement
hardware breakpoints and watchpoints for native debugging.

The SBI Debut Trigger extension (Draft v6) can be found at:
https://lists.riscv.org/g/tech-debug/topic/99825362#1302

This patch is an initial implementation of SBI Debug
Trigger Extension (Draft v6) in OpenSBI.

The following features are supported:
 * mcontrol, mcontrol6 triggers
 * Breakpoint and trace actions

NOTE: Chained triggers are not supported

Signed-off-by: Himanshu Chauhan <hchauhan@ventanamicro.com>
Reviewed-by: Anup Patel <anup@brainfault.org>

include/sbi/sbi_dbtr.h

@@ -0,0 +1,125 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2023 Ventana Micro Systems, Inc.
+ *
+ * Authors:
+ *   Himanshu Chauhan <hchauhan@ventanamicro.com>
+ */
+
+#ifndef __SBI_DBTR_H__
+#define __SBI_DBTR_H__
+
+#include <sbi/riscv_dbtr.h>
+#include <sbi/sbi_types.h>
+
+struct sbi_domain;
+
+enum {
+	RV_DBTR_DECLARE_BIT(TS, MAPPED, 0), /* trigger mapped to hw trigger */
+	RV_DBTR_DECLARE_BIT(TS, U, 1),
+	RV_DBTR_DECLARE_BIT(TS, S, 2),
+	RV_DBTR_DECLARE_BIT(TS, VU, 3),
+	RV_DBTR_DECLARE_BIT(TS, VS, 4),
+	RV_DBTR_DECLARE_BIT(TS, HAVE_TRIG, 5), /* H/w dbtr details available */
+	RV_DBTR_DECLARE_BIT(TS, HW_IDX, 8), /* Hardware index of trigger */
+};
+
+enum {
+	RV_DBTR_DECLARE_BIT_MASK(TS, MAPPED, 1),
+	RV_DBTR_DECLARE_BIT_MASK(TS, U, 1),
+	RV_DBTR_DECLARE_BIT_MASK(TS, S, 1),
+	RV_DBTR_DECLARE_BIT_MASK(TS, VU, 1),
+	RV_DBTR_DECLARE_BIT_MASK(TS, VS, 1),
+	RV_DBTR_DECLARE_BIT_MASK(TS, HAVE_TRIG, 1),
+	RV_DBTR_DECLARE_BIT_MASK(TS, HW_IDX, (__riscv_xlen-9)),
+};
+
+#if __riscv_xlen == 64
+#define SBI_DBTR_SHMEM_INVALID_ADDR	0xFFFFFFFFFFFFFFFFUL
+#elif __riscv_xlen == 32
+#define SBI_DBTR_SHMEM_INVALID_ADDR	0xFFFFFFFFUL
+#else
+#error "Unexpected __riscv_xlen"
+#endif
+
+struct sbi_dbtr_shmem {
+	unsigned long phys_lo;
+	unsigned long phys_hi;
+};
+
+struct sbi_dbtr_trigger {
+	unsigned long index;
+	unsigned long type_mask;
+	unsigned long state;
+	unsigned long tdata1;
+	unsigned long tdata2;
+	unsigned long tdata3;
+};
+
+struct sbi_dbtr_data_msg {
+	unsigned long tstate;
+	unsigned long tdata1;
+	unsigned long tdata2;
+	unsigned long tdata3;
+};
+
+struct sbi_dbtr_id_msg {
+	unsigned long idx;
+};
+
+struct sbi_dbtr_hart_triggers_state {
+	struct sbi_dbtr_trigger triggers[RV_MAX_TRIGGERS];
+	struct sbi_dbtr_shmem shmem;
+	u32 total_trigs;
+	u32 available_trigs;
+	u32 hartid;
+	u32 probed;
+};
+
+#define TDATA1_GET_TYPE(_t1)					\
+	EXTRACT_FIELD(_t1, RV_DBTR_BIT_MASK(TDATA1, TYPE))
+
+/* Set the hardware index of trigger in logical trigger state */
+#define SET_TRIG_HW_INDEX(_state, _idx)				\
+	do {							\
+		_state &= ~RV_DBTR_BIT_MASK(TS, HW_IDX);	\
+		_state |= (((unsigned long)_idx			\
+			    << RV_DBTR_BIT(TS, HW_IDX))		\
+			   & RV_DBTR_BIT_MASK(TS, HW_IDX));	\
+	}while (0);
+
+/** SBI shared mem messages layout */
+struct sbi_dbtr_shmem_entry {
+	struct sbi_dbtr_data_msg data;
+	struct sbi_dbtr_id_msg id;
+};
+
+#define SBI_DBTR_SHMEM_ALIGN_MASK	((__riscv_xlen / 8) - 1)
+
+/** Initialize debug triggers */
+int sbi_dbtr_init(struct sbi_scratch *scratch, bool coldboot);
+
+/** SBI DBTR extension functions */
+int sbi_dbtr_supported(void);
+int sbi_dbtr_setup_shmem(const struct sbi_domain *dom, unsigned long smode,
+			 unsigned long shmem_phys_lo,
+			 unsigned long shmem_phys_hi);
+int sbi_dbtr_num_trig(unsigned long trig_tdata1, unsigned long *out);
+int sbi_dbtr_read_trig(unsigned long smode,
+		       unsigned long trig_idx_base, unsigned long trig_count);
+int sbi_dbtr_install_trig(unsigned long smode,
+			  unsigned long trig_count, unsigned long *out);
+int sbi_dbtr_uninstall_trig(unsigned long trig_idx_base,
+			    unsigned long trig_idx_mask);
+int sbi_dbtr_enable_trig(unsigned long trig_idx_base,
+			 unsigned long trig_idx_mask);
+int sbi_dbtr_update_trig(unsigned long smode,
+			 unsigned long trig_idx_base,
+			 unsigned long trig_idx_mask);
+int sbi_dbtr_disable_trig(unsigned long trig_idx_base,
+			  unsigned long trig_idx_mask);
+
+int sbi_dbtr_get_total_triggers(void);
+
+#endif

lib/sbi/objects.mk

@@ -70,6 +70,7 @@ libsbi-objs-y += sbi_irqchip.o
 libsbi-objs-y += sbi_misaligned_ldst.o
 libsbi-objs-y += sbi_platform.o
 libsbi-objs-y += sbi_pmu.o
+libsbi-objs-y += sbi_dbtr.o
 libsbi-objs-y += sbi_scratch.o
 libsbi-objs-y += sbi_string.o
 libsbi-objs-y += sbi_system.o