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(+)
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,
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;
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:
- 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).
- Split into separate patches for CPU pm and CPU hotplug handling.
- 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
-
Mathieu Poirier -
Mike Leach