target/riscv: generalize custom CSR functionality

While at it, constify it so that the RISCVCSR array in RISCVCPUDef
can also be const.

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

target/riscv/cpu.c

@@ -485,6 +485,19 @@ static void set_satp_mode_default_map(RISCVCPU *cpu)
 }
 #endif
 
+#ifndef CONFIG_USER_ONLY
+static void riscv_register_custom_csrs(RISCVCPU *cpu, const RISCVCSR *csr_list)
+{
+    for (size_t i = 0; csr_list[i].csr_ops.name; i++) {
+        int csrno = csr_list[i].csrno;
+        const riscv_csr_operations *csr_ops = &csr_list[i].csr_ops;
+        if (!csr_list[i].insertion_test || csr_list[i].insertion_test(cpu)) {
+            riscv_set_csr_ops(csrno, csr_ops);
+        }
+    }
+}
+#endif
+
 #if defined(TARGET_RISCV64)
 static void rv64_thead_c906_cpu_init(Object *obj)
 {
@@ -511,7 +524,7 @@ static void rv64_thead_c906_cpu_init(Object *obj)
     cpu->cfg.mvendorid = THEAD_VENDOR_ID;
 #ifndef CONFIG_USER_ONLY
     set_satp_mode_max_supported(cpu, VM_1_10_SV39);
-    th_register_custom_csrs(cpu);
+    riscv_register_custom_csrs(cpu, th_csr_list);
 #endif
 
     /* inherited from parent obj via riscv_cpu_init() */
@@ -1304,6 +1317,11 @@ static void riscv_cpu_init(Object *obj)
     if (mcc->def->vext_spec != RISCV_PROFILE_ATTR_UNUSED) {
         cpu->env.vext_ver = mcc->def->vext_spec;
     }
+#ifndef CONFIG_USER_ONLY
+    if (mcc->def->custom_csrs) {
+        riscv_register_custom_csrs(cpu, mcc->def->custom_csrs);
+    }
+#endif
 }
 
 typedef struct misa_ext_info {
@@ -2906,6 +2924,11 @@ static void riscv_cpu_class_base_init(ObjectClass *c, const void *data)
         mcc->def->misa_ext |= def->misa_ext;
 
         riscv_cpu_cfg_merge(&mcc->def->cfg, &def->cfg);
+
+        if (def->custom_csrs) {
+            assert(!mcc->def->custom_csrs);
+            mcc->def->custom_csrs = def->custom_csrs;
+        }
     }
 
     if (!object_class_is_abstract(c)) {

target/riscv/cpu.h

@@ -538,6 +538,8 @@ struct ArchCPU {
     const GPtrArray *decoders;
 };
 
+typedef struct RISCVCSR RISCVCSR;
+
 typedef struct RISCVCPUDef {
     RISCVMXL misa_mxl_max;  /* max mxl for this cpu */
     RISCVCPUProfile *profile;
@@ -546,6 +548,7 @@ typedef struct RISCVCPUDef {
     int32_t vext_spec;
     RISCVCPUConfig cfg;
     bool bare;
+    const RISCVCSR *custom_csrs;
 } RISCVCPUDef;
 
 /**
@@ -893,6 +896,12 @@ typedef struct {
     uint32_t min_priv_ver;
 } riscv_csr_operations;
 
+struct RISCVCSR {
+    int csrno;
+    bool (*insertion_test)(RISCVCPU *cpu);
+    riscv_csr_operations csr_ops;
+};
+
 /* CSR function table constants */
 enum {
     CSR_TABLE_SIZE = 0x1000
@@ -947,7 +956,7 @@ extern riscv_csr_operations csr_ops[CSR_TABLE_SIZE];
 extern const bool valid_vm_1_10_32[], valid_vm_1_10_64[];
 
 void riscv_get_csr_ops(int csrno, riscv_csr_operations *ops);
-void riscv_set_csr_ops(int csrno, riscv_csr_operations *ops);
+void riscv_set_csr_ops(int csrno, const riscv_csr_operations *ops);
 
 void riscv_cpu_register_gdb_regs_for_features(CPUState *cs);
 
@@ -956,8 +965,8 @@ target_ulong riscv_new_csr_seed(target_ulong new_value,
 
 const char *satp_mode_str(uint8_t satp_mode, bool is_32_bit);
 
-/* Implemented in th_csr.c */
+/* In th_csr.c */
-void th_register_custom_csrs(RISCVCPU *cpu);
+extern const RISCVCSR th_csr_list[];
 
 const char *priv_spec_to_str(int priv_version);
 #endif /* RISCV_CPU_H */

target/riscv/csr.c

@@ -40,7 +40,7 @@ void riscv_get_csr_ops(int csrno, riscv_csr_operations *ops)
     *ops = csr_ops[csrno & (CSR_TABLE_SIZE - 1)];
 }
 
-void riscv_set_csr_ops(int csrno, riscv_csr_operations *ops)
+void riscv_set_csr_ops(int csrno, const riscv_csr_operations *ops)
 {
     csr_ops[csrno & (CSR_TABLE_SIZE - 1)] = *ops;
 }

target/riscv/th_csr.c

@@ -27,12 +27,6 @@
 #define TH_SXSTATUS_MAEE        BIT(21)
 #define TH_SXSTATUS_THEADISAEE  BIT(22)
 
-typedef struct {
-    int csrno;
-    bool (*insertion_test)(RISCVCPU *cpu);
-    riscv_csr_operations csr_ops;
-} riscv_csr;
-
 static RISCVException smode(CPURISCVState *env, int csrno)
 {
     if (riscv_has_ext(env, RVS)) {
@@ -55,20 +49,11 @@ static RISCVException read_th_sxstatus(CPURISCVState *env, int csrno,
     return RISCV_EXCP_NONE;
 }
 
-static riscv_csr th_csr_list[] = {
+const RISCVCSR th_csr_list[] = {
     {
         .csrno = CSR_TH_SXSTATUS,
         .insertion_test = test_thead_mvendorid,
         .csr_ops = { "th.sxstatus", smode, read_th_sxstatus }
-    }
+    },
+    { }
 };
-void th_register_custom_csrs(RISCVCPU *cpu)
-{
-    for (size_t i = 0; i < ARRAY_SIZE(th_csr_list); i++) {
-        int csrno = th_csr_list[i].csrno;
-        riscv_csr_operations *csr_ops = &th_csr_list[i].csr_ops;
-        if (!th_csr_list[i].insertion_test || th_csr_list[i].insertion_test(cpu)) {
-            riscv_set_csr_ops(csrno, csr_ops);
-        }
-    }
-}