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coresight: cti: Add CPU Hotplug handling to CTI driver 

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>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20200518180242.7916-23-mathieu.poirier@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Mike Leach 2020-05-18 12:02:41 -06:00 committed by Greg Kroah-Hartman
parent 3f4943d422
commit e9b880581d
2 changed files with 93 additions and 0 deletions
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92
drivers/hwtracing/coresight/coresight-cti.c
View File

@ -8,6 +8,7 @@
#include <linux/atomic.h>
#include <linux/bits.h>
#include <linux/coresight.h>
#include <linux/cpuhotplug.h>
#include <linux/device.h>
#include <linux/io.h>
#include <linux/kernel.h>
@ -40,6 +41,12 @@ 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 +136,35 @@ 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 +656,44 @@ 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 +729,7 @@ 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 +805,22 @@ 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 +859,7 @@ static int cti_probe(struct amba_device *adev, const struct amba_id *id)
return 0;
err_out:
cti_pm_release(drvdata);
return ret;
}

1
include/linux/cpuhotplug.h
View File

@ -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,