MIPS/BUS/CDMM: Convert to hotplug state machine

Install the callbacks via the state machine and let the core invoke
the callbacks on the already online CPUs.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160818125731.27256-14-bigeasy@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 12 insertions, 58 deletions

diff --git a/drivers/bus/mips_cdmm.c b/drivers/bus/mips_cdmm.c
index cad49bc38b3e..1b14256376d2 100644
--- a/drivers/bus/mips_cdmm.c
+++ b/drivers/bus/mips_cdmm.c
@@ -596,19 +596,20 @@ BUILD_PERDEV_HELPER(cpu_down)       /* int mips_cdmm_cpu_down_helper(...) */
 BUILD_PERDEV_HELPER(cpu_up)         /* int mips_cdmm_cpu_up_helper(...) */
 
 /**
- * mips_cdmm_bus_down() - Tear down the CDMM bus.
- * @data:       Pointer to unsigned int CPU number.
+ * mips_cdmm_cpu_down_prep() - Callback for CPUHP DOWN_PREP:
+ *                             Tear down the CDMM bus.
+ * @cpu:        unsigned int CPU number.
  *
  * This function is executed on the hotplugged CPU and calls the CDMM
  * driver cpu_down callback for all devices on that CPU.
  */
-static long mips_cdmm_bus_down(void *data)
+static int mips_cdmm_cpu_down_prep(unsigned int cpu)
 {
         struct mips_cdmm_bus *bus;
         long ret;
 
         /* Inform all the devices on the bus */
-        ret = bus_for_each_dev(&mips_cdmm_bustype, NULL, data,
+        ret = bus_for_each_dev(&mips_cdmm_bustype, NULL, &cpu,
                                mips_cdmm_cpu_down_helper);
 
         /*
@@ -623,8 +624,8 @@ static long mips_cdmm_bus_down(void *data)
 }
 
 /**
- * mips_cdmm_bus_up() - Bring up the CDMM bus.
- * @data:       Pointer to unsigned int CPU number.
+ * mips_cdmm_cpu_online() - Callback for CPUHP ONLINE: Bring up the CDMM bus.
+ * @cpu:        unsigned int CPU number.
  *
  * This work_on_cpu callback function is executed on a given CPU to discover
  * CDMM devices on that CPU, or to call the CDMM driver cpu_up callback for all
@@ -634,7 +635,7 @@ static long mips_cdmm_bus_down(void *data)
  * initialisation. When CPUs are brought online the function is
  * invoked directly on the hotplugged CPU.
  */
-static long mips_cdmm_bus_up(void *data)
+static int mips_cdmm_cpu_online(unsigned int cpu)
 {
         struct mips_cdmm_bus *bus;
         long ret;
@@ -651,51 +652,13 @@ static long mips_cdmm_bus_up(void *data)
                 mips_cdmm_bus_discover(bus);
         else
                 /* Inform all the devices on the bus */
-                ret = bus_for_each_dev(&mips_cdmm_bustype, NULL, data,
+                ret = bus_for_each_dev(&mips_cdmm_bustype, NULL, &cpu,
                                        mips_cdmm_cpu_up_helper);
 
         return ret;
 }
 
 /**
- * mips_cdmm_cpu_notify() - Take action when a CPU is going online or offline.
- * @nb:         CPU notifier block .
- * @action:     Event that has taken place (CPU_*).
- * @data:       CPU number.
- *
- * This notifier is used to keep the CDMM buses updated as CPUs are offlined and
- * onlined. When CPUs go offline or come back online, so does their CDMM bus, so
- * devices must be informed. Also when CPUs come online for the first time the
- * devices on the CDMM bus need discovering.
- *
- * Returns:     NOTIFY_OK if event was used.
- *              NOTIFY_DONE if we didn't care.
- */
-static int mips_cdmm_cpu_notify(struct notifier_block *nb,
-                                unsigned long action, void *data)
-{
-        unsigned int cpu = (unsigned int)data;
-
-        switch (action & ~CPU_TASKS_FROZEN) {
-        case CPU_ONLINE:
-        case CPU_DOWN_FAILED:
-                mips_cdmm_bus_up(&cpu);
-                break;
-        case CPU_DOWN_PREPARE:
-                mips_cdmm_bus_down(&cpu);
-                break;
-        default:
-                return NOTIFY_DONE;
-        }
-
-        return NOTIFY_OK;
-}
-
-static struct notifier_block mips_cdmm_cpu_nb = {
-        .notifier_call = mips_cdmm_cpu_notify,
-};
-
-/**
  * mips_cdmm_init() - Initialise CDMM bus.
  *
  * Initialise CDMM bus, discover CDMM devices for online CPUs, and arrange for
@@ -703,7 +666,6 @@ static struct notifier_block mips_cdmm_cpu_nb = {
  */
 static int __init mips_cdmm_init(void)
 {
-        unsigned int cpu;
         int ret;
 
         /* Register the bus */
@@ -712,19 +674,11 @@ static int __init mips_cdmm_init(void)
                 return ret;
 
         /* We want to be notified about new CPUs */
-        ret = register_cpu_notifier(&mips_cdmm_cpu_nb);
-        if (ret) {
+        ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "bus/cdmm:online",
+                                mips_cdmm_cpu_online, mips_cdmm_cpu_down_prep);
+        if (ret < 0)
                 pr_warn("cdmm: Failed to register CPU notifier\n");
-                goto out;
-        }
-
-        /* Discover devices on CDMM of online CPUs */
-        for_each_online_cpu(cpu)
-                work_on_cpu(cpu, mips_cdmm_bus_up, &cpu);
 
-        return 0;
-out:
-        bus_unregister(&mips_cdmm_bustype);
         return ret;
 }
 subsys_initcall(mips_cdmm_init);