ppc: allow the hdecr timer to be created/destroyed

Machines which don't emulate the HDEC facility are able to use the
timer for something else. Provide functions to start and stop the
hdecr timer.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[ clg: checkpatch fixes ]
Message-Id: <20220216102545.1808018-4-npiggin@gmail.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>

hw/ppc/ppc.c

@@ -1083,6 +1083,27 @@ clk_setup_cb cpu_ppc_tb_init (CPUPPCState *env, uint32_t freq)
     return &cpu_ppc_set_tb_clk;
 }
 
+/* cpu_ppc_hdecr_init may be used if the timer is not used by HDEC emulation */
+void cpu_ppc_hdecr_init(CPUPPCState *env)
+{
+    PowerPCCPU *cpu = env_archcpu(env);
+
+    assert(env->tb_env->hdecr_timer == NULL);
+
+    env->tb_env->hdecr_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL,
+                                            &cpu_ppc_hdecr_cb, cpu);
+}
+
+void cpu_ppc_hdecr_exit(CPUPPCState *env)
+{
+    PowerPCCPU *cpu = env_archcpu(env);
+
+    timer_free(env->tb_env->hdecr_timer);
+    env->tb_env->hdecr_timer = NULL;
+
+    cpu_ppc_hdecr_lower(cpu);
+}
+
 /*****************************************************************************/
 /* PowerPC 40x timers */
 

include/hw/ppc/ppc.h

@@ -54,6 +54,9 @@ struct ppc_tb_t {
 
 uint64_t cpu_ppc_get_tb(ppc_tb_t *tb_env, uint64_t vmclk, int64_t tb_offset);
 clk_setup_cb cpu_ppc_tb_init (CPUPPCState *env, uint32_t freq);
+void cpu_ppc_hdecr_init(CPUPPCState *env);
+void cpu_ppc_hdecr_exit(CPUPPCState *env);
+
 /* Embedded PowerPC DCR management */
 typedef uint32_t (*dcr_read_cb)(void *opaque, int dcrn);
 typedef void (*dcr_write_cb)(void *opaque, int dcrn, uint32_t val);