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* [PATCH v3 0/2] Add CPU power management for CPU bound CTI devices.
@ 2020-05-11 20:48 Mike Leach
  2020-05-11 20:48 ` [PATCH v3 1/2] coresight: cti: Add CPU Hotplug handling to CTI driver Mike Leach
                   ` (2 more replies)
  0 siblings, 3 replies; 4+ messages in thread
From: Mike Leach @ 2020-05-11 20:48 UTC (permalink / raw)
  To: linux-arm-kernel, coresight, mathieu.poirier
  Cc: tglx, Mike Leach, suzuki.poulose

Adds in power management for CPU bound CTI devices:
i) CPU Hotplug - registers a new notifier for CPU start and stop events.
ii) CPU idle PM event notifier to handle PM_ENTER, PM_ENTER_FAILED and
PM_EXIT events.

Tested with DB410c on coresight/next tree (Linux 5.7-rc1)

Changes since v2:
1) removed helper functions filtering on CONFIG_CPU_PM to call cpu_pm
fns directly.
2) add check for return value from cpuhp_remove_state_nocalls().

Changes since V1: (requested by Mathieu).
1) Split into separate patches for CPU pm and CPU hotplug handling.
2) Enable on hotplug has a specific function to enable the hardware,
while leaving the enable reference counts unchanged.

Mike Leach (2):
  coresight: cti: Add CPU Hotplug handling to CTI driver.
  coresight: cti: Add CPU idle pm notifer to CTI devices.

 drivers/hwtracing/coresight/coresight-cti.c | 160 ++++++++++++++++++++
 include/linux/cpuhotplug.h                  |   1 +
 2 files changed, 161 insertions(+)

-- 
2.17.1


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^ permalink raw reply	[flat|nested] 4+ messages in thread

* [PATCH v3 1/2] coresight: cti: Add CPU Hotplug handling to CTI driver.
  2020-05-11 20:48 [PATCH v3 0/2] Add CPU power management for CPU bound CTI devices Mike Leach
@ 2020-05-11 20:48 ` Mike Leach
  2020-05-11 20:48 ` [PATCH v3 2/2] coresight: cti: Add CPU idle pm notifer to CTI devices Mike Leach
  2020-05-14 17:12 ` [PATCH v3 0/2] Add CPU power management for CPU bound " Mathieu Poirier
  2 siblings, 0 replies; 4+ messages in thread
From: Mike Leach @ 2020-05-11 20:48 UTC (permalink / raw)
  To: linux-arm-kernel, coresight, mathieu.poirier
  Cc: tglx, Mike Leach, suzuki.poulose

Adds registration of CPU start and stop functions to CPU hotplug
mechanisms - for any CPU bound CTI.

Sets CTI powered flag according to state.
Will enable CTI on CPU start if there are existing enable requests.

Signed-off-by: Mike Leach <mike.leach@linaro.org>
---
 drivers/hwtracing/coresight/coresight-cti.c | 91 +++++++++++++++++++++
 include/linux/cpuhotplug.h                  |  1 +
 2 files changed, 92 insertions(+)

diff --git a/drivers/hwtracing/coresight/coresight-cti.c b/drivers/hwtracing/coresight/coresight-cti.c
index be61c1705916..716cd5a45d12 100644
--- a/drivers/hwtracing/coresight/coresight-cti.c
+++ b/drivers/hwtracing/coresight/coresight-cti.c
@@ -40,6 +40,12 @@ static DEFINE_MUTEX(ect_mutex);
 #define csdev_to_cti_drvdata(csdev)	\
 	dev_get_drvdata(csdev->dev.parent)
 
+/* power management handling */
+static int nr_cti_cpu;
+
+/* quick lookup list for CPU bound CTIs when power handling */
+static struct cti_drvdata *cti_cpu_drvdata[NR_CPUS];
+
 /*
  * CTI naming. CTI bound to cores will have the name cti_cpu<N> where
  * N is the CPU ID. System CTIs will have the name cti_sys<I> where I
@@ -129,6 +135,35 @@ static int cti_enable_hw(struct cti_drvdata *drvdata)
 	return rc;
 }
 
+/* re-enable CTI on CPU when using CPU hotplug */
+static void cti_cpuhp_enable_hw(struct cti_drvdata *drvdata)
+{
+	struct cti_config *config = &drvdata->config;
+	struct device *dev = &drvdata->csdev->dev;
+
+	pm_runtime_get_sync(dev->parent);
+	spin_lock(&drvdata->spinlock);
+	config->hw_powered = true;
+
+	/* no need to do anything if no enable request */
+	if (!atomic_read(&drvdata->config.enable_req_count))
+		goto cti_hp_not_enabled;
+
+	/* try to claim the device */
+	if (coresight_claim_device(drvdata->base))
+		goto cti_hp_not_enabled;
+
+	cti_write_all_hw_regs(drvdata);
+	config->hw_enabled = true;
+	spin_unlock(&drvdata->spinlock);
+	return;
+
+	/* did not re-enable due to no claim / no request */
+cti_hp_not_enabled:
+	spin_unlock(&drvdata->spinlock);
+	pm_runtime_put(dev->parent);
+}
+
 /* disable hardware */
 static int cti_disable_hw(struct cti_drvdata *drvdata)
 {
@@ -620,6 +655,44 @@ static void cti_remove_conn_xrefs(struct cti_drvdata *drvdata)
 	}
 }
 
+/* CPU HP handlers */
+static int cti_starting_cpu(unsigned int cpu)
+{
+	struct cti_drvdata *drvdata = cti_cpu_drvdata[cpu];
+
+	if (!drvdata)
+		return 0;
+
+	cti_cpuhp_enable_hw(drvdata);
+	return 0;
+}
+
+static int cti_dying_cpu(unsigned int cpu)
+{
+	struct cti_drvdata *drvdata = cti_cpu_drvdata[cpu];
+
+	if (!drvdata)
+		return 0;
+
+	spin_lock(&drvdata->spinlock);
+	drvdata->config.hw_powered = false;
+	coresight_disclaim_device(drvdata->base);
+	spin_unlock(&drvdata->spinlock);
+	return 0;
+}
+
+/* release PM registrations */
+static void cti_pm_release(struct cti_drvdata *drvdata)
+{
+	if (drvdata->ctidev.cpu >= 0) {
+		if (--nr_cti_cpu == 0) {
+			cpuhp_remove_state_nocalls(
+				CPUHP_AP_ARM_CORESIGHT_CTI_STARTING);
+		}
+		cti_cpu_drvdata[drvdata->ctidev.cpu] = NULL;
+	}
+}
+
 /** cti ect operations **/
 int cti_enable(struct coresight_device *csdev)
 {
@@ -655,6 +728,7 @@ static void cti_device_release(struct device *dev)
 
 	mutex_lock(&ect_mutex);
 	cti_remove_conn_xrefs(drvdata);
+	cti_pm_release(drvdata);
 
 	/* remove from the list */
 	list_for_each_entry_safe(ect_item, ect_tmp, &ect_net, node) {
@@ -730,6 +804,22 @@ static int cti_probe(struct amba_device *adev, const struct amba_id *id)
 		goto err_out;
 	}
 
+	/* setup CPU power management handling for CPU bound CTI devices. */
+	if (drvdata->ctidev.cpu >= 0) {
+		cti_cpu_drvdata[drvdata->ctidev.cpu] = drvdata;
+		if (!nr_cti_cpu++) {
+			cpus_read_lock();
+			ret = cpuhp_setup_state_nocalls_cpuslocked(
+				CPUHP_AP_ARM_CORESIGHT_CTI_STARTING,
+				"arm/coresight_cti:starting",
+				cti_starting_cpu, cti_dying_cpu);
+
+			cpus_read_unlock();
+			if (ret)
+				goto err_out;
+		}
+	}
+
 	/* create dynamic attributes for connections */
 	ret = cti_create_cons_sysfs(dev, drvdata);
 	if (ret) {
@@ -768,6 +858,7 @@ static int cti_probe(struct amba_device *adev, const struct amba_id *id)
 	return 0;
 
 err_out:
+	cti_pm_release(drvdata);
 	return ret;
 }
 
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 77d70b633531..6dc7332307ca 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -142,6 +142,7 @@ enum cpuhp_state {
 	CPUHP_AP_ARM_XEN_STARTING,
 	CPUHP_AP_ARM_KVMPV_STARTING,
 	CPUHP_AP_ARM_CORESIGHT_STARTING,
+	CPUHP_AP_ARM_CORESIGHT_CTI_STARTING,
 	CPUHP_AP_ARM64_ISNDEP_STARTING,
 	CPUHP_AP_SMPCFD_DYING,
 	CPUHP_AP_X86_TBOOT_DYING,
-- 
2.17.1


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linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

^ permalink raw reply related	[flat|nested] 4+ messages in thread

* [PATCH v3 2/2] coresight: cti: Add CPU idle pm notifer to CTI devices.
  2020-05-11 20:48 [PATCH v3 0/2] Add CPU power management for CPU bound CTI devices Mike Leach
  2020-05-11 20:48 ` [PATCH v3 1/2] coresight: cti: Add CPU Hotplug handling to CTI driver Mike Leach
@ 2020-05-11 20:48 ` Mike Leach
  2020-05-14 17:12 ` [PATCH v3 0/2] Add CPU power management for CPU bound " Mathieu Poirier
  2 siblings, 0 replies; 4+ messages in thread
From: Mike Leach @ 2020-05-11 20:48 UTC (permalink / raw)
  To: linux-arm-kernel, coresight, mathieu.poirier
  Cc: tglx, Mike Leach, suzuki.poulose

Adds a notify callback for CPU PM events to the CTI driver - for
CPU bound CTI devices.

Signed-off-by: Mike Leach <mike.leach@linaro.org>
---
 drivers/hwtracing/coresight/coresight-cti.c | 69 +++++++++++++++++++++
 1 file changed, 69 insertions(+)

diff --git a/drivers/hwtracing/coresight/coresight-cti.c b/drivers/hwtracing/coresight/coresight-cti.c
index 716cd5a45d12..5886663a641d 100644
--- a/drivers/hwtracing/coresight/coresight-cti.c
+++ b/drivers/hwtracing/coresight/coresight-cti.c
@@ -8,6 +8,7 @@
 #include <linux/atomic.h>
 #include <linux/bits.h>
 #include <linux/coresight.h>
+#include <linux/cpu_pm.h>
 #include <linux/device.h>
 #include <linux/io.h>
 #include <linux/kernel.h>
@@ -655,6 +656,70 @@ static void cti_remove_conn_xrefs(struct cti_drvdata *drvdata)
 	}
 }
 
+/** cti PM callbacks **/
+static int cti_cpu_pm_notify(struct notifier_block *nb, unsigned long cmd,
+			     void *v)
+{
+	struct cti_drvdata *drvdata;
+	unsigned int cpu = smp_processor_id();
+	int notify_res = NOTIFY_OK;
+
+	if (!cti_cpu_drvdata[cpu])
+		return NOTIFY_OK;
+
+	drvdata = cti_cpu_drvdata[cpu];
+
+	if (WARN_ON_ONCE(drvdata->ctidev.cpu != cpu))
+		return NOTIFY_BAD;
+
+	spin_lock(&drvdata->spinlock);
+
+	switch (cmd) {
+	case CPU_PM_ENTER:
+		/* CTI regs all static - we have a copy & nothing to save */
+		drvdata->config.hw_powered = false;
+		if (drvdata->config.hw_enabled)
+			coresight_disclaim_device(drvdata->base);
+		break;
+
+	case CPU_PM_ENTER_FAILED:
+		drvdata->config.hw_powered = true;
+		if (drvdata->config.hw_enabled) {
+			if (coresight_claim_device(drvdata->base))
+				drvdata->config.hw_enabled = false;
+		}
+		break;
+
+	case CPU_PM_EXIT:
+		/* write hardware registers to re-enable. */
+		drvdata->config.hw_powered = true;
+		drvdata->config.hw_enabled = false;
+
+		/* check enable reference count to enable HW */
+		if (atomic_read(&drvdata->config.enable_req_count)) {
+			/* check we can claim the device as we re-power */
+			if (coresight_claim_device(drvdata->base))
+				goto cti_notify_exit;
+
+			drvdata->config.hw_enabled = true;
+			cti_write_all_hw_regs(drvdata);
+		}
+		break;
+
+	default:
+		notify_res = NOTIFY_DONE;
+		break;
+	}
+
+cti_notify_exit:
+	spin_unlock(&drvdata->spinlock);
+	return notify_res;
+}
+
+static struct notifier_block cti_cpu_pm_nb = {
+	.notifier_call = cti_cpu_pm_notify,
+};
+
 /* CPU HP handlers */
 static int cti_starting_cpu(unsigned int cpu)
 {
@@ -686,6 +751,8 @@ static void cti_pm_release(struct cti_drvdata *drvdata)
 {
 	if (drvdata->ctidev.cpu >= 0) {
 		if (--nr_cti_cpu == 0) {
+			cpu_pm_unregister_notifier(&cti_cpu_pm_nb);
+
 			cpuhp_remove_state_nocalls(
 				CPUHP_AP_ARM_CORESIGHT_CTI_STARTING);
 		}
@@ -814,6 +881,8 @@ static int cti_probe(struct amba_device *adev, const struct amba_id *id)
 				"arm/coresight_cti:starting",
 				cti_starting_cpu, cti_dying_cpu);
 
+			if (!ret)
+				ret = cpu_pm_register_notifier(&cti_cpu_pm_nb);
 			cpus_read_unlock();
 			if (ret)
 				goto err_out;
-- 
2.17.1


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linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

^ permalink raw reply related	[flat|nested] 4+ messages in thread

* Re: [PATCH v3 0/2] Add CPU power management for CPU bound CTI devices.
  2020-05-11 20:48 [PATCH v3 0/2] Add CPU power management for CPU bound CTI devices Mike Leach
  2020-05-11 20:48 ` [PATCH v3 1/2] coresight: cti: Add CPU Hotplug handling to CTI driver Mike Leach
  2020-05-11 20:48 ` [PATCH v3 2/2] coresight: cti: Add CPU idle pm notifer to CTI devices Mike Leach
@ 2020-05-14 17:12 ` Mathieu Poirier
  2 siblings, 0 replies; 4+ messages in thread
From: Mathieu Poirier @ 2020-05-14 17:12 UTC (permalink / raw)
  To: Mike Leach; +Cc: coresight, tglx, linux-arm-kernel, suzuki.poulose

On Mon, May 11, 2020 at 09:48:34PM +0100, Mike Leach wrote:
> Adds in power management for CPU bound CTI devices:
> i) CPU Hotplug - registers a new notifier for CPU start and stop events.
> ii) CPU idle PM event notifier to handle PM_ENTER, PM_ENTER_FAILED and
> PM_EXIT events.
> 
> Tested with DB410c on coresight/next tree (Linux 5.7-rc1)
> 
> Changes since v2:
> 1) removed helper functions filtering on CONFIG_CPU_PM to call cpu_pm
> fns directly.
> 2) add check for return value from cpuhp_remove_state_nocalls().
> 
> Changes since V1: (requested by Mathieu).
> 1) Split into separate patches for CPU pm and CPU hotplug handling.
> 2) Enable on hotplug has a specific function to enable the hardware,
> while leaving the enable reference counts unchanged.
> 
> Mike Leach (2):
>   coresight: cti: Add CPU Hotplug handling to CTI driver.
>   coresight: cti: Add CPU idle pm notifer to CTI devices.

I have applied this set.

Thanks,
Mathieu

> 
>  drivers/hwtracing/coresight/coresight-cti.c | 160 ++++++++++++++++++++
>  include/linux/cpuhotplug.h                  |   1 +
>  2 files changed, 161 insertions(+)
> 
> -- 
> 2.17.1
> 

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^ permalink raw reply	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2020-05-14 17:12 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-05-11 20:48 [PATCH v3 0/2] Add CPU power management for CPU bound CTI devices Mike Leach
2020-05-11 20:48 ` [PATCH v3 1/2] coresight: cti: Add CPU Hotplug handling to CTI driver Mike Leach
2020-05-11 20:48 ` [PATCH v3 2/2] coresight: cti: Add CPU idle pm notifer to CTI devices Mike Leach
2020-05-14 17:12 ` [PATCH v3 0/2] Add CPU power management for CPU bound " Mathieu Poirier

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