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Subject[patch V2 51/67] hwtracing/coresight-etm3x: Convert to hotplug state machine
From: Richard Cochran <rcochran@linutronix.de>

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>
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
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
drivers/hwtracing/coresight/coresight-etm3x.c | 90 ++++++++++++++------------
include/linux/cpuhotplug.h | 1
2 files changed, 50 insertions(+), 41 deletions(-)

--- a/drivers/hwtracing/coresight/coresight-etm3x.c
+++ b/drivers/hwtracing/coresight/coresight-etm3x.c
@@ -51,6 +51,8 @@ module_param_named(boot_enable, boot_ena
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 cores

/*
* 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
.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
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

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
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;
}

--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -50,6 +50,7 @@ enum cpuhp_state {
CPUHP_AP_KVM_ARM_VGIC_STARTING,
CPUHP_AP_KVM_ARM_TIMER_STARTING,
CPUHP_AP_ARM_XEN_STARTING,
+ CPUHP_AP_ARM_CORESIGHT_STARTING,
CPUHP_AP_LEDTRIG_STARTING,
CPUHP_AP_NOTIFY_STARTING,
CPUHP_AP_ONLINE,

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