[PATCH v2 5/8] target/riscv: debug: Introduce tinfo CSR

[Bin Meng]

From: Frank Chang <frank.chang@sifive.com>

tinfo.info:
  One bit for each possible type enumerated in tdata1.
  If the bit is set, then that type is supported by the currently
  selected trigger.

Signed-off-by: Frank Chang <frank.chang@sifive.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
---

(no changes since v1)

 target/riscv/cpu_bits.h |  1 +
 target/riscv/debug.h    |  2 ++
 target/riscv/csr.c      |  8 ++++++++
 target/riscv/debug.c    | 10 +++++++---
 4 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/target/riscv/cpu_bits.h b/target/riscv/cpu_bits.h
index 7be12cac2e..1972aee3bb 100644
--- a/target/riscv/cpu_bits.h
+++ b/target/riscv/cpu_bits.h
@@ -321,6 +321,7 @@
 #define CSR_TDATA1          0x7a1
 #define CSR_TDATA2          0x7a2
 #define CSR_TDATA3          0x7a3
+#define CSR_TINFO           0x7a4
 
 /* Debug Mode Registers */
 #define CSR_DCSR            0x7b0
diff --git a/target/riscv/debug.h b/target/riscv/debug.h
index 76146f373a..9f69c64591 100644
--- a/target/riscv/debug.h
+++ b/target/riscv/debug.h
@@ -95,6 +95,8 @@ void tselect_csr_write(CPURISCVState *env, target_ulong val);
 target_ulong tdata_csr_read(CPURISCVState *env, int tdata_index);
 void tdata_csr_write(CPURISCVState *env, int tdata_index, target_ulong val);
 
+target_ulong tinfo_csr_read(CPURISCVState *env);
+
 void riscv_cpu_debug_excp_handler(CPUState *cs);
 bool riscv_cpu_debug_check_breakpoint(CPUState *cs);
 bool riscv_cpu_debug_check_watchpoint(CPUState *cs, CPUWatchpoint *wp);
diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index 3d0d8e0340..e66019048d 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -3089,6 +3089,13 @@ static RISCVException write_tdata(CPURISCVState *env, 
int csrno,
     return RISCV_EXCP_NONE;
 }
 
+static RISCVException read_tinfo(CPURISCVState *env, int csrno,
+                                 target_ulong *val)
+{
+    *val = tinfo_csr_read(env);
+    return RISCV_EXCP_NONE;
+}
+
 /*
  * Functions to access Pointer Masking feature registers
  * We have to check if current priv lvl could modify
@@ -3893,6 +3900,7 @@ riscv_csr_operations csr_ops[CSR_TABLE_SIZE] = {
     [CSR_TDATA1]    =  { "tdata1",  debug, read_tdata,   write_tdata   },
     [CSR_TDATA2]    =  { "tdata2",  debug, read_tdata,   write_tdata   },
     [CSR_TDATA3]    =  { "tdata3",  debug, read_tdata,   write_tdata   },
+    [CSR_TINFO]     =  { "tinfo",   debug, read_tinfo,   write_ignore  },
 
     /* User Pointer Masking */
     [CSR_UMTE]    =    { "umte",    pointer_masking, read_umte,  write_umte },
diff --git a/target/riscv/debug.c b/target/riscv/debug.c
index d6666164cd..7d546ace42 100644
--- a/target/riscv/debug.c
+++ b/target/riscv/debug.c
@@ -37,9 +37,7 @@
  * - tdata1
  * - tdata2
  * - tdata3
- *
- * We don't support writable 'type' field in the tdata1 register, so there is
- * no need to implement the "tinfo" CSR.
+ * - tinfo
  *
  * The following triggers are implemented:
  *
@@ -372,6 +370,12 @@ void tdata_csr_write(CPURISCVState *env, int tdata_index, 
target_ulong val)
     }
 }
 
+target_ulong tinfo_csr_read(CPURISCVState *env)
+{
+    /* assume all triggers support the same types of triggers */
+    return BIT(TRIGGER_TYPE_AD_MATCH);
+}
+
 void riscv_cpu_debug_excp_handler(CPUState *cs)
 {
     RISCVCPU *cpu = RISCV_CPU(cs);
-- 
2.34.1