On some platforms, the TMC driver may probe before the associated CPUs are online. This prevents the driver from securely accessing the hardware or configuring it via smp_call_function_single(), which requires the target CPU to be available.
To address this, defer the hardware initialization if the associated CPUs are offline: 1. Track such deferred devices in a global list. 2. Register a CPU hotplug callback (`tmc_online_cpu`) to detect when a relevant CPU comes online. 3. Upon CPU online, retry the hardware initialization and registration for the waiting TMC devices.
Signed-off-by: Yuanfang Zhang yuanfang.zhang@oss.qualcomm.com --- drivers/hwtracing/coresight/coresight-tmc-core.c | 59 +++++++++++++++++++++++- drivers/hwtracing/coresight/coresight-tmc.h | 4 ++ 2 files changed, 61 insertions(+), 2 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-tmc-core.c b/drivers/hwtracing/coresight/coresight-tmc-core.c index 5b9f2e57c78f42f0f1460d8a8dcbac72b5f6085e..9182fa8e4074a7c9739494b2f5d59be2e96f1d3d 100644 --- a/drivers/hwtracing/coresight/coresight-tmc-core.c +++ b/drivers/hwtracing/coresight/coresight-tmc-core.c @@ -36,6 +36,9 @@ DEFINE_CORESIGHT_DEVLIST(etb_devs, "tmc_etb"); DEFINE_CORESIGHT_DEVLIST(etf_devs, "tmc_etf"); DEFINE_CORESIGHT_DEVLIST(etr_devs, "tmc_etr"); +static LIST_HEAD(tmc_delay_probe); +static enum cpuhp_state hp_online; +static DEFINE_SPINLOCK(delay_lock);
int tmc_wait_for_tmcready(struct tmc_drvdata *drvdata) { @@ -1027,6 +1030,8 @@ static int __tmc_probe(struct device *dev, struct resource *res) if (!drvdata->supported_cpus) return -EINVAL;
+ drvdata->dev = dev; + cpus_read_lock(); for_each_cpu(cpu, drvdata->supported_cpus) { ret = smp_call_function_single(cpu, @@ -1034,11 +1039,16 @@ static int __tmc_probe(struct device *dev, struct resource *res) if (!ret) break; } - cpus_read_unlock(); + if (ret) { + scoped_guard(spinlock, &delay_lock) + list_add(&drvdata->link, &tmc_delay_probe); + cpus_read_unlock(); ret = 0; goto out; } + + cpus_read_unlock(); } else { tmc_init_hw_config(drvdata); } @@ -1103,8 +1113,12 @@ static void __tmc_remove(struct device *dev) misc_deregister(&drvdata->miscdev); if (drvdata->crashdev.fops) misc_deregister(&drvdata->crashdev); - if (drvdata->csdev) + if (drvdata->csdev) { coresight_unregister(drvdata->csdev); + } else { + scoped_guard(spinlock, &delay_lock) + list_del(&drvdata->link); + } }
static void tmc_remove(struct amba_device *adev) @@ -1215,14 +1229,55 @@ static struct platform_driver tmc_platform_driver = { }, };
+static int tmc_online_cpu(unsigned int cpu) +{ + struct tmc_drvdata *drvdata, *tmp; + int ret; + + spin_lock(&delay_lock); + list_for_each_entry_safe(drvdata, tmp, &tmc_delay_probe, link) { + if (cpumask_test_cpu(cpu, drvdata->supported_cpus)) { + list_del(&drvdata->link); + + spin_unlock(&delay_lock); + ret = pm_runtime_resume_and_get(drvdata->dev); + if (ret < 0) + return 0; + + tmc_init_hw_config(drvdata); + tmc_clear_self_claim_tag(drvdata); + tmc_add_coresight_dev(drvdata->dev); + pm_runtime_put(drvdata->dev); + spin_lock(&delay_lock); + } + } + spin_unlock(&delay_lock); + return 0; +} + static int __init tmc_init(void) { + int ret; + + ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, + "arm/coresight-tmc:online", + tmc_online_cpu, NULL); + + if (ret > 0) + hp_online = ret; + else + return ret; + return coresight_init_driver("tmc", &tmc_driver, &tmc_platform_driver, THIS_MODULE); }
static void __exit tmc_exit(void) { coresight_remove_driver(&tmc_driver, &tmc_platform_driver); + if (hp_online) { + cpuhp_remove_state_nocalls(hp_online); + hp_online = 0; + } } module_init(tmc_init); module_exit(tmc_exit); diff --git a/drivers/hwtracing/coresight/coresight-tmc.h b/drivers/hwtracing/coresight/coresight-tmc.h index b104b7bf82d2a7a99382636e41d3718cf258d820..2583bc4f556195cd814e674dc66f08909dea61b2 100644 --- a/drivers/hwtracing/coresight/coresight-tmc.h +++ b/drivers/hwtracing/coresight/coresight-tmc.h @@ -246,6 +246,8 @@ struct tmc_resrv_buf { * @supported_cpus: Represent the CPUs related to this TMC. * @devid: TMC variant ID inferred from the device configuration register. * @desc_name: Name to be used while creating crash interface. + * @dev: pointer to the device associated with this TMC. + * @link: link to the delay_probed list. */ struct tmc_drvdata { struct clk *atclk; @@ -279,6 +281,8 @@ struct tmc_drvdata { struct cpumask *supported_cpus; u32 devid; const char *desc_name; + struct device *dev; + struct list_head link; };
struct etr_buf_operations {