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Subject[patch V2 52/67] hwtracing/coresight-etm4x: Convert to hotplug state machine
From: Sebastian Andrzej Siewior <bigeasy@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: 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-etm4x.c | 85 ++++++++++++++------------
include/linux/cpuhotplug.h | 1
2 files changed, 49 insertions(+), 37 deletions(-)

--- a/drivers/hwtracing/coresight/coresight-etm4x.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x.c
@@ -48,6 +48,8 @@ static int etm4_count;
static struct etmv4_drvdata *etmdrvdata[NR_CPUS];
static void etm4_set_default(struct etmv4_config *config);

+static enum cpuhp_state hp_online;
+
static void etm4_os_unlock(struct etmv4_drvdata *drvdata)
{
/* Writing any value to ETMOSLAR unlocks the trace registers */
@@ -673,47 +675,44 @@ void etm4_config_trace_mode(struct etmv4
config->addr_acc[ETM_DEFAULT_ADDR_COMP + 1] = addr_acc;
}

-static int etm4_cpu_callback(struct notifier_block *nfb, unsigned long action,
- void *hcpu)
+static int etm4_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) {
- etm4_os_unlock(etmdrvdata[cpu]);
- etmdrvdata[cpu]->os_unlock = true;
- }
-
- if (local_read(&etmdrvdata[cpu]->mode))
- etm4_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 etm4_starting_cpu(unsigned int cpu)
+{
+ if (!etmdrvdata[cpu])
+ return 0;

- case CPU_DYING:
- spin_lock(&etmdrvdata[cpu]->spinlock);
- if (local_read(&etmdrvdata[cpu]->mode))
- etm4_disable_hw(etmdrvdata[cpu]);
- spin_unlock(&etmdrvdata[cpu]->spinlock);
- break;
+ spin_lock(&etmdrvdata[cpu]->spinlock);
+ if (!etmdrvdata[cpu]->os_unlock) {
+ etm4_os_unlock(etmdrvdata[cpu]);
+ etmdrvdata[cpu]->os_unlock = true;
}
-out:
- return NOTIFY_OK;
+
+ if (local_read(&etmdrvdata[cpu]->mode))
+ etm4_enable_hw(etmdrvdata[cpu]);
+ spin_unlock(&etmdrvdata[cpu]->spinlock);
+ return 0;
}

-static struct notifier_block etm4_cpu_notifier = {
- .notifier_call = etm4_cpu_callback,
-};
+static int etm4_dying_cpu(unsigned int cpu)
+{
+ if (!etmdrvdata[cpu])
+ return 0;
+
+ spin_lock(&etmdrvdata[cpu]->spinlock);
+ if (local_read(&etmdrvdata[cpu]->mode))
+ etm4_disable_hw(etmdrvdata[cpu]);
+ spin_unlock(&etmdrvdata[cpu]->spinlock);
+ return 0;
+}

static void etm4_init_trace_id(struct etmv4_drvdata *drvdata)
{
@@ -767,8 +766,17 @@ static int etm4_probe(struct amba_device
etm4_init_arch_data, drvdata, 1))
dev_err(dev, "ETM arch init failed\n");

- if (!etm4_count++)
- register_hotcpu_notifier(&etm4_cpu_notifier);
+ if (!etm4_count++) {
+ cpuhp_setup_state_nocalls(CPUHP_AP_ARM_CORESIGHT4_STARTING,
+ "AP_ARM_CORESIGHT4_STARTING",
+ etm4_starting_cpu, etm4_dying_cpu);
+ ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
+ "AP_ARM_CORESIGHT4_ONLINE",
+ etm4_online_cpu, NULL);
+ if (ret < 0)
+ goto err_arch_supported;
+ hp_online = ret;
+ }

put_online_cpus();

@@ -809,8 +817,11 @@ static int etm4_probe(struct amba_device
return 0;

err_arch_supported:
- if (--etm4_count == 0)
- unregister_hotcpu_notifier(&etm4_cpu_notifier);
+ if (--etm4_count == 0) {
+ cpuhp_remove_state_nocalls(CPUHP_AP_ARM_CORESIGHT4_STARTING);
+ if (hp_online)
+ cpuhp_remove_state_nocalls(hp_online);
+ }
return ret;
}

--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -51,6 +51,7 @@ enum cpuhp_state {
CPUHP_AP_KVM_ARM_TIMER_STARTING,
CPUHP_AP_ARM_XEN_STARTING,
CPUHP_AP_ARM_CORESIGHT_STARTING,
+ CPUHP_AP_ARM_CORESIGHT4_STARTING,
CPUHP_AP_LEDTRIG_STARTING,
CPUHP_AP_NOTIFY_STARTING,
CPUHP_AP_ONLINE,

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