diff options
author | Tamas Zsoldos | 2022-07-05 16:59:35 +0200 |
---|---|---|
committer | Suzuki K Poulose | 2022-10-31 10:32:46 +0000 |
commit | 3c728e079d83f581a1f8b7755f6e26087b15c4fb (patch) | |
tree | 720137b9354f70a4fdfe91bec1bf1516b48194d6 /drivers/hwtracing | |
parent | 30a0b95b1335e12efef89dd78518ed3e4a71a763 (diff) |
coresight: etm4x: add CPU hotplug support for probing
etm4x devices cannot be successfully probed when their CPU is offline.
For example, when booting with maxcpus=n, ETM probing will fail on
CPUs >n, and the probing won't be reattempted once the CPUs come
online. This will leave those CPUs unable to make use of ETM.
This change adds a mechanism to delay the probing if the corresponding
CPU is offline, and to try it again when the CPU comes online.
Signed-off-by: Tamas Zsoldos <tamas.zsoldos@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20220705145935.24679-1-tamas.zsoldos@arm.com
Diffstat (limited to 'drivers/hwtracing')
-rw-r--r-- | drivers/hwtracing/coresight/coresight-etm4x-core.c | 153 |
1 files changed, 113 insertions, 40 deletions
diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c index 80fefaba58ee..9dc0d7f57565 100644 --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c @@ -66,10 +66,13 @@ static enum cpuhp_state hp_online; struct etm4_init_arg { unsigned int pid; - struct etmv4_drvdata *drvdata; + struct device *dev; struct csdev_access *csa; }; +static DEFINE_PER_CPU(struct etm4_init_arg *, delayed_probe); +static int etm4_probe_cpu(unsigned int cpu); + /* * Check if TRCSSPCICRn(i) is implemented for a given instance. * @@ -1085,7 +1088,7 @@ static void etm4_init_arch_data(void *info) struct csdev_access *csa; int i; - drvdata = init_arg->drvdata; + drvdata = dev_get_drvdata(init_arg->dev); csa = init_arg->csa; /* @@ -1528,7 +1531,7 @@ void etm4_config_trace_mode(struct etmv4_config *config) static int etm4_online_cpu(unsigned int cpu) { if (!etmdrvdata[cpu]) - return 0; + return etm4_probe_cpu(cpu); if (etmdrvdata[cpu]->boot_enable && !etmdrvdata[cpu]->sticky_enable) coresight_enable(etmdrvdata[cpu]->csdev); @@ -1904,48 +1907,20 @@ static void etm4_pm_clear(void) } } -static int etm4_probe(struct device *dev, void __iomem *base, u32 etm_pid) +static int etm4_add_coresight_dev(struct etm4_init_arg *init_arg) { int ret; struct coresight_platform_data *pdata = NULL; - struct etmv4_drvdata *drvdata; + struct device *dev = init_arg->dev; + struct etmv4_drvdata *drvdata = dev_get_drvdata(dev); struct coresight_desc desc = { 0 }; - struct etm4_init_arg init_arg = { 0 }; u8 major, minor; char *type_name; - drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL); if (!drvdata) - return -ENOMEM; - - dev_set_drvdata(dev, drvdata); - - if (pm_save_enable == PARAM_PM_SAVE_FIRMWARE) - pm_save_enable = coresight_loses_context_with_cpu(dev) ? - PARAM_PM_SAVE_SELF_HOSTED : PARAM_PM_SAVE_NEVER; - - if (pm_save_enable != PARAM_PM_SAVE_NEVER) { - drvdata->save_state = devm_kmalloc(dev, - sizeof(struct etmv4_save_state), GFP_KERNEL); - if (!drvdata->save_state) - return -ENOMEM; - } - - drvdata->base = base; - - spin_lock_init(&drvdata->spinlock); - - drvdata->cpu = coresight_get_cpu(dev); - if (drvdata->cpu < 0) - return drvdata->cpu; - - init_arg.drvdata = drvdata; - init_arg.csa = &desc.access; - init_arg.pid = etm_pid; + return -EINVAL; - if (smp_call_function_single(drvdata->cpu, - etm4_init_arch_data, &init_arg, 1)) - dev_err(dev, "ETM arch init failed\n"); + desc.access = *init_arg->csa; if (!drvdata->arch) return -EINVAL; @@ -2016,6 +1991,68 @@ static int etm4_probe(struct device *dev, void __iomem *base, u32 etm_pid) return 0; } +static int etm4_probe(struct device *dev, void __iomem *base, u32 etm_pid) +{ + struct etmv4_drvdata *drvdata; + struct csdev_access access = { 0 }; + struct etm4_init_arg init_arg = { 0 }; + struct etm4_init_arg *delayed; + + drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL); + if (!drvdata) + return -ENOMEM; + + dev_set_drvdata(dev, drvdata); + + if (pm_save_enable == PARAM_PM_SAVE_FIRMWARE) + pm_save_enable = coresight_loses_context_with_cpu(dev) ? + PARAM_PM_SAVE_SELF_HOSTED : PARAM_PM_SAVE_NEVER; + + if (pm_save_enable != PARAM_PM_SAVE_NEVER) { + drvdata->save_state = devm_kmalloc(dev, + sizeof(struct etmv4_save_state), GFP_KERNEL); + if (!drvdata->save_state) + return -ENOMEM; + } + + drvdata->base = base; + + spin_lock_init(&drvdata->spinlock); + + drvdata->cpu = coresight_get_cpu(dev); + if (drvdata->cpu < 0) + return drvdata->cpu; + + init_arg.dev = dev; + init_arg.csa = &access; + init_arg.pid = etm_pid; + + /* + * Serialize against CPUHP callbacks to avoid race condition + * between the smp call and saving the delayed probe. + */ + cpus_read_lock(); + if (smp_call_function_single(drvdata->cpu, + etm4_init_arch_data, &init_arg, 1)) { + /* The CPU was offline, try again once it comes online. */ + delayed = devm_kmalloc(dev, sizeof(*delayed), GFP_KERNEL); + if (!delayed) { + cpus_read_unlock(); + return -ENOMEM; + } + + *delayed = init_arg; + + per_cpu(delayed_probe, drvdata->cpu) = delayed; + + cpus_read_unlock(); + return 0; + } + cpus_read_unlock(); + + return etm4_add_coresight_dev(&init_arg); +} + static int etm4_probe_amba(struct amba_device *adev, const struct amba_id *id) { void __iomem *base; @@ -2054,6 +2091,35 @@ static int etm4_probe_platform_dev(struct platform_device *pdev) return ret; } +static int etm4_probe_cpu(unsigned int cpu) +{ + int ret; + struct etm4_init_arg init_arg; + struct csdev_access access = { 0 }; + struct etm4_init_arg *iap = *this_cpu_ptr(&delayed_probe); + + if (!iap) + return 0; + + init_arg = *iap; + devm_kfree(init_arg.dev, iap); + *this_cpu_ptr(&delayed_probe) = NULL; + + ret = pm_runtime_resume_and_get(init_arg.dev); + if (ret < 0) { + dev_err(init_arg.dev, "Failed to get PM runtime!\n"); + return 0; + } + + init_arg.csa = &access; + etm4_init_arch_data(&init_arg); + + etm4_add_coresight_dev(&init_arg); + + pm_runtime_put(init_arg.dev); + return 0; +} + static struct amba_cs_uci_id uci_id_etm4[] = { { /* ETMv4 UCI data */ @@ -2068,16 +2134,20 @@ static void clear_etmdrvdata(void *info) int cpu = *(int *)info; etmdrvdata[cpu] = NULL; + per_cpu(delayed_probe, cpu) = NULL; } static int __exit etm4_remove_dev(struct etmv4_drvdata *drvdata) { - etm_perf_symlink(drvdata->csdev, false); + bool had_delayed_probe; /* * Taking hotplug lock here to avoid racing between etm4_remove_dev() * and CPU hotplug call backs. */ cpus_read_lock(); + + had_delayed_probe = per_cpu(delayed_probe, drvdata->cpu); + /* * The readers for etmdrvdata[] are CPU hotplug call backs * and PM notification call backs. Change etmdrvdata[i] on @@ -2085,12 +2155,15 @@ static int __exit etm4_remove_dev(struct etmv4_drvdata *drvdata) * inside one call back function. */ if (smp_call_function_single(drvdata->cpu, clear_etmdrvdata, &drvdata->cpu, 1)) - etmdrvdata[drvdata->cpu] = NULL; + clear_etmdrvdata(&drvdata->cpu); cpus_read_unlock(); - cscfg_unregister_csdev(drvdata->csdev); - coresight_unregister(drvdata->csdev); + if (!had_delayed_probe) { + etm_perf_symlink(drvdata->csdev, false); + cscfg_unregister_csdev(drvdata->csdev); + coresight_unregister(drvdata->csdev); + } return 0; } |