Re: [PATCH v2 1/2] coresight: cti: Add CPU Hotplug handling to CTI driver.

Hi Mike,

On Mon, May 04, 2020 at 05:15:29PM +0100, Mike Leach wrote:

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..9af66719ae5b 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();
  

• 	cpuhp_setup_state_nocalls_cpuslocked(
  

ret = cpuhp_setup_state_nocalls_cpuslocked(

Otherwise this patch looks good to me (many thanks for splitting). On your next revision please CC Thomas Gleixner as suggested by the get_maintainer.pl script.

Mathieu

• 		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