hwtracing/coresight-etm3x: Convert to hotplug state machine

This driver has an asymmetry of ONLINE code without any corresponding tear
down code. Otherwise, this is a straightforward conversion.

Signed-off-by: Richard Cochran <rcochran@linutronix.de>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arm-kernel@lists.infradead.org
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160713153337.147128995@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 49 insertions, 41 deletions

diff --git a/drivers/hwtracing/coresight/coresight-etm3x.c b/drivers/hwtracing/coresight/coresight-etm3x.c
index d83ab82672e4..2de4cad9c5ed 100644
--- a/drivers/hwtracing/coresight/coresight-etm3x.c
+++ b/drivers/hwtracing/coresight/coresight-etm3x.c
@@ -51,6 +51,8 @@ module_param_named(boot_enable, boot_enable, int, S_IRUGO);
 static int etm_count;
 static struct etm_drvdata *etmdrvdata[NR_CPUS];
 
+static enum cpuhp_state hp_online;
+
 /*
  * Memory mapped writes to clear os lock are not supported on some processors
  * and OS lock must be unlocked before any memory mapped access on such
@@ -481,8 +483,7 @@ static int etm_enable_sysfs(struct coresight_device *csdev)
 
         /*
          * Configure the ETM only if the CPU is online.  If it isn't online
-         * hw configuration will take place when 'CPU_STARTING' is received
-         * in @etm_cpu_callback.
+         * hw configuration will take place on the local CPU during bring up.
          */
         if (cpu_online(drvdata->cpu)) {
                 ret = smp_call_function_single(drvdata->cpu,
@@ -641,47 +642,44 @@ static const struct coresight_ops etm_cs_ops = {
         .source_ops     = &etm_source_ops,
 };
 
-static int etm_cpu_callback(struct notifier_block *nfb, unsigned long action,
-                            void *hcpu)
+static int etm_online_cpu(unsigned int cpu)
 {
-        unsigned int cpu = (unsigned long)hcpu;
-
         if (!etmdrvdata[cpu])
-                goto out;
+                return 0;
 
-        switch (action & (~CPU_TASKS_FROZEN)) {
-        case CPU_STARTING:
-                spin_lock(&etmdrvdata[cpu]->spinlock);
-                if (!etmdrvdata[cpu]->os_unlock) {
-                        etm_os_unlock(etmdrvdata[cpu]);
-                        etmdrvdata[cpu]->os_unlock = true;
-                }
-
-                if (local_read(&etmdrvdata[cpu]->mode))
-                        etm_enable_hw(etmdrvdata[cpu]);
-                spin_unlock(&etmdrvdata[cpu]->spinlock);
-                break;
+        if (etmdrvdata[cpu]->boot_enable && !etmdrvdata[cpu]->sticky_enable)
+                coresight_enable(etmdrvdata[cpu]->csdev);
+        return 0;
+}
 
-        case CPU_ONLINE:
-                if (etmdrvdata[cpu]->boot_enable &&
-                    !etmdrvdata[cpu]->sticky_enable)
-                        coresight_enable(etmdrvdata[cpu]->csdev);
-                break;
+static int etm_starting_cpu(unsigned int cpu)
+{
+        if (!etmdrvdata[cpu])
+                return 0;
 
-        case CPU_DYING:
-                spin_lock(&etmdrvdata[cpu]->spinlock);
-                if (local_read(&etmdrvdata[cpu]->mode))
-                        etm_disable_hw(etmdrvdata[cpu]);
-                spin_unlock(&etmdrvdata[cpu]->spinlock);
-                break;
+        spin_lock(&etmdrvdata[cpu]->spinlock);
+        if (!etmdrvdata[cpu]->os_unlock) {
+                etm_os_unlock(etmdrvdata[cpu]);
+                etmdrvdata[cpu]->os_unlock = true;
         }
-out:
-        return NOTIFY_OK;
+
+        if (local_read(&etmdrvdata[cpu]->mode))
+                etm_enable_hw(etmdrvdata[cpu]);
+        spin_unlock(&etmdrvdata[cpu]->spinlock);
+        return 0;
 }
 
-static struct notifier_block etm_cpu_notifier = {
-        .notifier_call = etm_cpu_callback,
-};
+static int etm_dying_cpu(unsigned int cpu)
+{
+        if (!etmdrvdata[cpu])
+                return 0;
+
+        spin_lock(&etmdrvdata[cpu]->spinlock);
+        if (local_read(&etmdrvdata[cpu]->mode))
+                etm_disable_hw(etmdrvdata[cpu]);
+        spin_unlock(&etmdrvdata[cpu]->spinlock);
+        return 0;
+}
 
 static bool etm_arch_supported(u8 arch)
 {
@@ -806,9 +804,17 @@ static int etm_probe(struct amba_device *adev, const struct amba_id *id)
                                      etm_init_arch_data,  drvdata, 1))
                 dev_err(dev, "ETM arch init failed\n");
 
-        if (!etm_count++)
-                register_hotcpu_notifier(&etm_cpu_notifier);
-
+        if (!etm_count++) {
+                cpuhp_setup_state_nocalls(CPUHP_AP_ARM_CORESIGHT_STARTING,
+                                          "AP_ARM_CORESIGHT_STARTING",
+                                          etm_starting_cpu, etm_dying_cpu);
+                ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
+                                                "AP_ARM_CORESIGHT_ONLINE",
+                                                etm_online_cpu, NULL);
+                if (ret < 0)
+                        goto err_arch_supported;
+                hp_online = ret;
+        }
         put_online_cpus();
 
         if (etm_arch_supported(drvdata->arch) == false) {
@@ -839,7 +845,6 @@ static int etm_probe(struct amba_device *adev, const struct amba_id *id)
 
         pm_runtime_put(&adev->dev);
         dev_info(dev, "%s initialized\n", (char *)id->data);
-
         if (boot_enable) {
                 coresight_enable(drvdata->csdev);
                 drvdata->boot_enable = true;
@@ -848,8 +853,11 @@ static int etm_probe(struct amba_device *adev, const struct amba_id *id)
         return 0;
 
 err_arch_supported:
-        if (--etm_count == 0)
-                unregister_hotcpu_notifier(&etm_cpu_notifier);
+        if (--etm_count == 0) {
+                cpuhp_remove_state_nocalls(CPUHP_AP_ARM_CORESIGHT_STARTING);
+                if (hp_online)
+                        cpuhp_remove_state_nocalls(hp_online);
+        }
         return ret;
 }