[PATCH 4/5] target/riscv: csr: Hook debug CSR read/write

[Bin Meng <bmeng.cn@gmail.com>]

This adds debug CSR read/write support to the RISC-V CSR RW table.

Signed-off-by: Bin Meng <bin.meng@windriver.com>
---

 target/riscv/cpu.c |  6 +++++
 target/riscv/csr.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 63 insertions(+)

diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index 3a2fa97098..45b054b294 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -563,6 +563,12 @@ static void riscv_cpu_realize(DeviceState *dev, Error **errp)
 
     riscv_cpu_register_gdb_regs_for_features(cs);
 
+#ifndef CONFIG_USER_ONLY
+    if (riscv_feature(env, RISCV_FEATURE_DEBUG)) {
+        riscv_trigger_init(env);
+    }
+#endif
+
     qemu_init_vcpu(cs);
     cpu_reset(cs);
 
diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index 69e4d65fcd..baa55efc91 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -209,6 +209,15 @@ static RISCVException epmp(CPURISCVState *env, int csrno)
 
     return RISCV_EXCP_ILLEGAL_INST;
 }
+
+static RISCVException debug(CPURISCVState *env, int csrno)
+{
+    if (riscv_feature(env, RISCV_FEATURE_DEBUG)) {
+        return RISCV_EXCP_NONE;
+    }
+
+    return RISCV_EXCP_ILLEGAL_INST;
+}
 #endif
 
 /* User Floating-Point CSRs */
@@ -1425,6 +1434,48 @@ static RISCVException write_pmpaddr(CPURISCVState *env, int csrno,
     return RISCV_EXCP_NONE;
 }
 
+static RISCVException read_tselect(CPURISCVState *env, int csrno,
+                                   target_ulong *val)
+{
+    *val = tselect_csr_read(env);
+    return RISCV_EXCP_NONE;
+}
+
+static RISCVException write_tselect(CPURISCVState *env, int csrno,
+                                    target_ulong val)
+{
+    tselect_csr_write(env, val);
+    return RISCV_EXCP_NONE;
+}
+
+static RISCVException read_tdata(CPURISCVState *env, int csrno,
+                                 target_ulong *val)
+{
+    /* return 0 in tdata1 to end the trigger enumeration */
+    if (env->trigger_cur >= TRIGGER_NUM && csrno == CSR_TDATA1) {
+        *val = 0;
+        return RISCV_EXCP_NONE;
+    }
+
+    if (!tdata_available(env, csrno - CSR_TDATA1)) {
+        return RISCV_EXCP_ILLEGAL_INST;
+    }
+
+    *val = tdata_csr_read(env, csrno - CSR_TDATA1);
+    return RISCV_EXCP_NONE;
+}
+
+static RISCVException write_tdata(CPURISCVState *env, int csrno,
+                                  target_ulong val)
+{
+    if (!tdata_available(env, csrno - CSR_TDATA1)) {
+        return RISCV_EXCP_ILLEGAL_INST;
+    }
+
+    tdata_csr_write(env, csrno - CSR_TDATA1, val);
+    return RISCV_EXCP_NONE;
+}
+
 #endif
 
 /*
@@ -1659,6 +1710,12 @@ riscv_csr_operations csr_ops[CSR_TABLE_SIZE] = {
     [CSR_PMPADDR14] =  { "pmpaddr14", pmp, read_pmpaddr, write_pmpaddr },
     [CSR_PMPADDR15] =  { "pmpaddr15", pmp, read_pmpaddr, write_pmpaddr },
 
+    /* Debug CSRs */
+    [CSR_TSELECT]   =  { "tselect", debug, read_tselect, write_tselect },
+    [CSR_TDATA1]    =  { "tdata1",  debug, read_tdata,   write_tdata   },
+    [CSR_TDATA2]    =  { "tdata2",  debug, read_tdata,   write_tdata   },
+    [CSR_TDATA3]    =  { "tdata3",  debug, read_tdata,   write_tdata   },
+
     /* Performance Counters */
     [CSR_HPMCOUNTER3]    = { "hpmcounter3",    ctr,    read_zero },
     [CSR_HPMCOUNTER4]    = { "hpmcounter4",    ctr,    read_zero },
-- 
2.25.1