diff options
| -rw-r--r-- | Documentation/driver-api/firmware/request_firmware.rst | 11 | ||||
| -rw-r--r-- | drivers/base/firmware_class.c | 99 |
2 files changed, 110 insertions, 0 deletions
diff --git a/Documentation/driver-api/firmware/request_firmware.rst b/Documentation/driver-api/firmware/request_firmware.rst index cc0aea8..1c2c496 100644 --- a/Documentation/driver-api/firmware/request_firmware.rst +++ b/Documentation/driver-api/firmware/request_firmware.rst @@ -44,6 +44,17 @@ request_firmware_nowait .. kernel-doc:: drivers/base/firmware_class.c :functions: request_firmware_nowait +Considerations for suspend and resume +===================================== + +During suspend and resume only the built-in firmware and the firmware cache +elements of the firmware API can be used. This is managed by fw_pm_notify(). + +fw_pm_notify +------------ +.. kernel-doc:: drivers/base/firmware_class.c + :functions: fw_pm_notify + request firmware API expected driver use ======================================== diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c index dd9b7f3..a272c86 100644 --- a/drivers/base/firmware_class.c +++ b/drivers/base/firmware_class.c @@ -260,6 +260,38 @@ static int fw_cache_piggyback_on_request(const char *name); * guarding for corner cases a global lock should be OK */ static DEFINE_MUTEX(fw_lock); +static bool __enable_firmware = false; + +static void enable_firmware(void) +{ + mutex_lock(&fw_lock); + __enable_firmware = true; + mutex_unlock(&fw_lock); +} + +static void disable_firmware(void) +{ + mutex_lock(&fw_lock); + __enable_firmware = false; + mutex_unlock(&fw_lock); +} + +/* + * When disabled only the built-in firmware and the firmware cache will be + * used to look for firmware. + */ +static bool firmware_enabled(void) +{ + bool enabled = false; + + mutex_lock(&fw_lock); + if (__enable_firmware) + enabled = true; + mutex_unlock(&fw_lock); + + return enabled; +} + static struct firmware_cache fw_cache; static struct firmware_buf *__allocate_fw_buf(const char *fw_name, @@ -1163,6 +1195,12 @@ _request_firmware(const struct firmware **firmware_p, const char *name, if (ret <= 0) /* error or already assigned */ goto out; + if (!firmware_enabled()) { + WARN(1, "firmware request while host is not available\n"); + ret = -EHOSTDOWN; + goto out; + } + ret = 0; timeout = firmware_loading_timeout(); if (opt_flags & FW_OPT_NOWAIT) { @@ -1695,6 +1733,62 @@ static void device_uncache_fw_images_delay(unsigned long delay) msecs_to_jiffies(delay)); } +/** + * fw_pm_notify - notifier for suspend/resume + * @notify_block: unused + * @mode: mode we are switching to + * @unused: unused + * + * Used to modify the firmware_class state as we move in between states. + * The firmware_class implements a firmware cache to enable device driver + * to fetch firmware upon resume before the root filesystem is ready. We + * disable API calls which do not use the built-in firmware or the firmware + * cache when we know these calls will not work. + * + * The inner logic behind all this is a bit complex so it is worth summarizing + * the kernel's own suspend/resume process with context and focus on how this + * can impact the firmware API. + * + * First a review on how we go to suspend:: + * + * pm_suspend() --> enter_state() --> + * sys_sync() + * suspend_prepare() --> + * __pm_notifier_call_chain(PM_SUSPEND_PREPARE, ...); + * suspend_freeze_processes() --> + * freeze_processes() --> + * __usermodehelper_set_disable_depth(UMH_DISABLED); + * freeze all tasks ... + * freeze_kernel_threads() + * suspend_devices_and_enter() --> + * dpm_suspend_start() --> + * dpm_prepare() + * dpm_suspend() + * suspend_enter() --> + * platform_suspend_prepare() + * dpm_suspend_late() + * freeze_enter() + * syscore_suspend() + * + * When we resume we bail out of a loop from suspend_devices_and_enter() and + * unwind back out to the caller enter_state() where we were before as follows:: + * + * enter_state() --> + * suspend_devices_and_enter() --> (bail from loop) + * dpm_resume_end() --> + * dpm_resume() + * dpm_complete() + * suspend_finish() --> + * suspend_thaw_processes() --> + * thaw_processes() --> + * __usermodehelper_set_disable_depth(UMH_FREEZING); + * thaw_workqueues(); + * thaw all processes ... + * usermodehelper_enable(); + * pm_notifier_call_chain(PM_POST_SUSPEND); + * + * fw_pm_notify() works through pm_notifier_call_chain(). + */ static int fw_pm_notify(struct notifier_block *notify_block, unsigned long mode, void *unused) { @@ -1708,6 +1802,7 @@ static int fw_pm_notify(struct notifier_block *notify_block, */ kill_pending_fw_fallback_reqs(true); device_cache_fw_images(); + disable_firmware(); break; case PM_POST_SUSPEND: @@ -1720,6 +1815,7 @@ static int fw_pm_notify(struct notifier_block *notify_block, mutex_lock(&fw_lock); fw_cache.state = FW_LOADER_NO_CACHE; mutex_unlock(&fw_lock); + enable_firmware(); device_uncache_fw_images_delay(10 * MSEC_PER_SEC); break; @@ -1768,6 +1864,7 @@ static void __init fw_cache_init(void) static int fw_shutdown_notify(struct notifier_block *unused1, unsigned long unused2, void *unused3) { + disable_firmware(); /* * Kill all pending fallback requests to avoid both stalling shutdown, * and avoid a deadlock with the usermode_lock. @@ -1783,6 +1880,7 @@ static struct notifier_block fw_shutdown_nb = { static int __init firmware_class_init(void) { + enable_firmware(); fw_cache_init(); register_reboot_notifier(&fw_shutdown_nb); #ifdef CONFIG_FW_LOADER_USER_HELPER @@ -1794,6 +1892,7 @@ static int __init firmware_class_init(void) static void __exit firmware_class_exit(void) { + disable_firmware(); #ifdef CONFIG_PM_SLEEP unregister_syscore_ops(&fw_syscore_ops); unregister_pm_notifier(&fw_cache.pm_notify); |
