Merge tag 'driver-core-6.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/driver-core/driver-core

Pull driver core updates from Danilo Krummrich:
 "Arch Topology:
   - Move parse_acpi_topology() from arm64 to common code for reuse in
     RISC-V

  CPU:
   - Expose housekeeping CPUs through /sys/devices/system/cpu/housekeeping
   - Print a newline (or 0x0A) instead of '(null)' reading
     /sys/devices/system/cpu/nohz_full when nohz_full= is not set

  debugfs
   - Remove (broken) 'no-mount' mode
   - Remove redundant access mode checks in debugfs_get_tree() and
     debugfs_create_*() functions

  Devres:
   - Remove unused devm_free_percpu() helper
   - Move devm_alloc_percpu() from device.h to devres.h

  Firmware Loader:
   - Replace simple_strtol() with kstrtoint()
   - Do not call cancel_store() when no upload is in progress

  kernfs:
   - Increase struct super_block::maxbytes to MAX_LFS_FILESIZE
   - Fix a missing unwind path in __kernfs_new_node()

  Misc:
   - Increase the name size in struct auxiliary_device_id to 40
     characters
   - Replace system_unbound_wq with system_dfl_wq and add WQ_PERCPU to
     alloc_workqueue()

  Platform:
   - Replace ERR_PTR() with IOMEM_ERR_PTR() in platform ioremap
     functions

  Rust:
   - Auxiliary:
      - Unregister auxiliary device on parent device unbind
      - Move parent() to impl Device; implement device context aware
        parent() for Device<Bound>
      - Illustrate how to safely obtain a driver's device private data
        when calling from an auxiliary driver into the parant device
        driver

   - DebugFs:
      - Implement support for binary large objects

   - Device:
      - Let probe() return the driver's device private data as pinned
        initializer, i.e. impl PinInit<Self, Error>
      - Implement safe accessor for a driver's device private data for
        Device<Bound> (returned reference can't out-live driver binding
        and guarantees the correct private data type)
      - Implement AsBusDevice trait, to be used by class device
        abstractions to derive the bus device type of the parent device

   - DMA:
      - Store raw pointer of allocation as NonNull
      - Use start_ptr() and start_ptr_mut() to inherit correct
        mutability of self

   - FS:
      - Add file::Offset type alias

   - I2C:
      - Add abstractions for I2C device / driver infrastructure
      - Implement abstractions for manual I2C device registrations

   - I/O:
      - Use "kernel vertical" style for imports
      - Define ResourceSize as resource_size_t
      - Move ResourceSize to top-level I/O module
      - Add type alias for phys_addr_t
      - Implement Rust version of read_poll_timeout_atomic()

   - PCI:
      - Use "kernel vertical" style for imports
      - Move I/O and IRQ infrastructure to separate files
      - Add support for PCI interrupt vectors
      - Implement TryInto<IrqRequest<'a>> for IrqVector<'a> to convert
        an IrqVector bound to specific pci::Device into an IrqRequest
        bound to the same pci::Device's parent Device
      - Leverage pin_init_scope() to get rid of redundant Result in IRQ
        methods

   - PinInit:
      - Add {pin_}init_scope() to execute code before creating an
        initializer

   - Platform:
      - Leverage pin_init_scope() to get rid of redundant Result in IRQ
        methods

   - Timekeeping:
      - Implement abstraction of udelay()

   - Uaccess:
      - Implement read_slice_partial() and read_slice_file() for
        UserSliceReader
      - Implement write_slice_partial() and write_slice_file() for
        UserSliceWriter

  sysfs:
   - Prepare the constification of struct attribute"

* tag 'driver-core-6.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/driver-core/driver-core: (75 commits)
  rust: pci: fix build failure when CONFIG_PCI_MSI is disabled
  debugfs: Fix default access mode config check
  debugfs: Remove broken no-mount mode
  debugfs: Remove redundant access mode checks
  driver core: Check drivers_autoprobe for all added devices
  driver core: WQ_PERCPU added to alloc_workqueue users
  driver core: replace use of system_unbound_wq with system_dfl_wq
  tick/nohz: Expose housekeeping CPUs in sysfs
  tick/nohz: avoid showing '(null)' if nohz_full= not set
  sysfs/cpu: Use DEVICE_ATTR_RO for nohz_full attribute
  kernfs: fix memory leak of kernfs_iattrs in __kernfs_new_node
  fs/kernfs: raise sb->maxbytes to MAX_LFS_FILESIZE
  mod_devicetable: Bump auxiliary_device_id name size
  sysfs: simplify attribute definition macros
  samples/kobject: constify 'struct foo_attribute'
  samples/kobject: add is_visible() callback to attribute group
  sysfs: attribute_group: enable const variants of is_visible()
  sysfs: introduce __SYSFS_FUNCTION_ALTERNATIVE()
  sysfs: transparently handle const pointers in ATTRIBUTE_GROUPS()
  sysfs: attribute_group: allow registration of const attribute
  ...

Author: torvalds

Documentation/ABI/testing/sysfs-devices-system-cpu

@@ -764,6 +764,17 @@ Description:
 		participate in load balancing. These CPUs are set by
 		boot parameter "isolcpus=".
 
+What:		/sys/devices/system/cpu/housekeeping
+Date:		Oct 2025
+Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
+Description:
+		(RO) the list of logical CPUs that are designated by the kernel as
+		"housekeeping". Each CPU are responsible for handling essential
+		system-wide background tasks, including RCU callbacks, delayed
+		timer callbacks, and unbound workqueues, minimizing scheduling
+		jitter on low-latency, isolated CPUs. These CPUs are set when boot
+		parameter "isolcpus=nohz" or "nohz_full=" is specified.
+
 What:		/sys/devices/system/cpu/crash_hotplug
 Date:		Aug 2023
 Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>

Documentation/admin-guide/kernel-parameters.txt

@@ -1211,12 +1211,8 @@ Kernel parameters
 
 	debugfs=    	[KNL,EARLY] This parameter enables what is exposed to
 			userspace and debugfs internal clients.
-			Format: { on, no-mount, off }
+			Format: { on, off }
 			on: 	All functions are enabled.
-			no-mount:
-				Filesystem is not registered but kernel clients can
-			        access APIs and a crashkernel can be used to read
-				its content. There is nothing to mount.
 			off: 	Filesystem is not registered and clients
 			        get a -EPERM as result when trying to register files
 				or directories within debugfs.

Documentation/driver-api/driver-model/devres.rst

@@ -383,7 +383,6 @@ NET
 
 PER-CPU MEM
   devm_alloc_percpu()
-  devm_free_percpu()
 
 PCI
   devm_pci_alloc_host_bridge()  : managed PCI host bridge allocation

MAINTAINERS

@@ -11821,6 +11821,16 @@ F:	include/linux/i2c.h
 F:	include/uapi/linux/i2c-*.h
 F:	include/uapi/linux/i2c.h
 
+I2C SUBSYSTEM [RUST]
+M:	Igor Korotin <igor.korotin.linux@gmail.com>
+R:	Danilo Krummrich <dakr@kernel.org>
+R:	Daniel Almeida <daniel.almeida@collabora.com>
+L:	rust-for-linux@vger.kernel.org
+S:	Maintained
+F:	rust/kernel/i2c.rs
+F:	samples/rust/rust_driver_i2c.rs
+F:	samples/rust/rust_i2c_client.rs
+
 I2C SUBSYSTEM HOST DRIVERS
 M:	Andi Shyti <andi.shyti@kernel.org>
 L:	linux-i2c@vger.kernel.org

arch/arm64/include/asm/topology.h

@@ -36,6 +36,9 @@ void update_freq_counters_refs(void);
 #define arch_scale_hw_pressure topology_get_hw_pressure
 #define arch_update_hw_pressure	topology_update_hw_pressure
 
+#undef arch_cpu_is_threaded
+#define arch_cpu_is_threaded() (read_cpuid_mpidr() & MPIDR_MT_BITMASK)
+
 #include <asm-generic/topology.h>
 
 #endif /* _ASM_ARM_TOPOLOGY_H */

arch/arm64/kernel/topology.c

@@ -25,107 +25,6 @@
 #include <asm/cputype.h>
 #include <asm/topology.h>
 
-#ifdef CONFIG_ACPI
-static bool __init acpi_cpu_is_threaded(int cpu)
-{
-	int is_threaded = acpi_pptt_cpu_is_thread(cpu);
-
-	/*
-	 * if the PPTT doesn't have thread information, assume a homogeneous
-	 * machine and return the current CPU's thread state.
-	 */
-	if (is_threaded < 0)
-		is_threaded = read_cpuid_mpidr() & MPIDR_MT_BITMASK;
-
-	return !!is_threaded;
-}
-
-struct cpu_smt_info {
-	unsigned int thread_num;
-	int core_id;
-};
-
-/*
- * Propagate the topology information of the processor_topology_node tree to the
- * cpu_topology array.
- */
-int __init parse_acpi_topology(void)
-{
-	unsigned int max_smt_thread_num = 1;
-	struct cpu_smt_info *entry;
-	struct xarray hetero_cpu;
-	unsigned long hetero_id;
-	int cpu, topology_id;
-
-	if (acpi_disabled)
-		return 0;
-
-	xa_init(&hetero_cpu);
-
-	for_each_possible_cpu(cpu) {
-		topology_id = find_acpi_cpu_topology(cpu, 0);
-		if (topology_id < 0)
-			return topology_id;
-
-		if (acpi_cpu_is_threaded(cpu)) {
-			cpu_topology[cpu].thread_id = topology_id;
-			topology_id = find_acpi_cpu_topology(cpu, 1);
-			cpu_topology[cpu].core_id   = topology_id;
-
-			/*
-			 * In the PPTT, CPUs below a node with the 'identical
-			 * implementation' flag have the same number of threads.
-			 * Count the number of threads for only one CPU (i.e.
-			 * one core_id) among those with the same hetero_id.
-			 * See the comment of find_acpi_cpu_topology_hetero_id()
-			 * for more details.
-			 *
-			 * One entry is created for each node having:
-			 * - the 'identical implementation' flag
-			 * - its parent not having the flag
-			 */
-			hetero_id = find_acpi_cpu_topology_hetero_id(cpu);
-			entry = xa_load(&hetero_cpu, hetero_id);
-			if (!entry) {
-				entry = kzalloc(sizeof(*entry), GFP_KERNEL);
-				WARN_ON_ONCE(!entry);
-
-				if (entry) {
-					entry->core_id = topology_id;
-					entry->thread_num = 1;
-					xa_store(&hetero_cpu, hetero_id,
-						 entry, GFP_KERNEL);
-				}
-			} else if (entry->core_id == topology_id) {
-				entry->thread_num++;
-			}
-		} else {
-			cpu_topology[cpu].thread_id  = -1;
-			cpu_topology[cpu].core_id    = topology_id;
-		}
-		topology_id = find_acpi_cpu_topology_cluster(cpu);
-		cpu_topology[cpu].cluster_id = topology_id;
-		topology_id = find_acpi_cpu_topology_package(cpu);
-		cpu_topology[cpu].package_id = topology_id;
-	}
-
-	/*
-	 * This is a short loop since the number of XArray elements is the
-	 * number of heterogeneous CPU clusters. On a homogeneous system
-	 * there's only one entry in the XArray.
-	 */
-	xa_for_each(&hetero_cpu, hetero_id, entry) {
-		max_smt_thread_num = max(max_smt_thread_num, entry->thread_num);
-		xa_erase(&hetero_cpu, hetero_id);
-		kfree(entry);
-	}
-
-	cpu_smt_set_num_threads(max_smt_thread_num, max_smt_thread_num);
-	xa_destroy(&hetero_cpu);
-	return 0;
-}
-#endif
-
 #ifdef CONFIG_ARM64_AMU_EXTN
 #define read_corecnt()	read_sysreg_s(SYS_AMEVCNTR0_CORE_EL0)
 #define read_constcnt()	read_sysreg_s(SYS_AMEVCNTR0_CONST_EL0)

drivers/base/arch_topology.c

@@ -823,12 +823,106 @@ void remove_cpu_topology(unsigned int cpu)
 	clear_cpu_topology(cpu);
 }
 
+#if defined(CONFIG_ARM64) || defined(CONFIG_RISCV)
+struct cpu_smt_info {
+	unsigned int thread_num;
+	int core_id;
+};
+
+static bool __init acpi_cpu_is_threaded(int cpu)
+{
+	int is_threaded = acpi_pptt_cpu_is_thread(cpu);
+
+	/*
+	 * if the PPTT doesn't have thread information, check for architecture
+	 * specific fallback if available
+	 */
+	if (is_threaded < 0)
+		is_threaded = arch_cpu_is_threaded();
+
+	return !!is_threaded;
+}
+
+/*
+ * Propagate the topology information of the processor_topology_node tree to the
+ * cpu_topology array.
+ */
 __weak int __init parse_acpi_topology(void)
 {
+	unsigned int max_smt_thread_num = 1;
+	struct cpu_smt_info *entry;
+	struct xarray hetero_cpu;
+	unsigned long hetero_id;
+	int cpu, topology_id;
+
+	if (acpi_disabled)
+		return 0;
+
+	xa_init(&hetero_cpu);
+
+	for_each_possible_cpu(cpu) {
+		topology_id = find_acpi_cpu_topology(cpu, 0);
+		if (topology_id < 0)
+			return topology_id;
+
+		if (acpi_cpu_is_threaded(cpu)) {
+			cpu_topology[cpu].thread_id = topology_id;
+			topology_id = find_acpi_cpu_topology(cpu, 1);
+			cpu_topology[cpu].core_id   = topology_id;
+
+			/*
+			 * In the PPTT, CPUs below a node with the 'identical
+			 * implementation' flag have the same number of threads.
+			 * Count the number of threads for only one CPU (i.e.
+			 * one core_id) among those with the same hetero_id.
+			 * See the comment of find_acpi_cpu_topology_hetero_id()
+			 * for more details.
+			 *
+			 * One entry is created for each node having:
+			 * - the 'identical implementation' flag
+			 * - its parent not having the flag
+			 */
+			hetero_id = find_acpi_cpu_topology_hetero_id(cpu);
+			entry = xa_load(&hetero_cpu, hetero_id);
+			if (!entry) {
+				entry = kzalloc(sizeof(*entry), GFP_KERNEL);
+				WARN_ON_ONCE(!entry);
+
+				if (entry) {
+					entry->core_id = topology_id;
+					entry->thread_num = 1;
+					xa_store(&hetero_cpu, hetero_id,
+						 entry, GFP_KERNEL);
+				}
+			} else if (entry->core_id == topology_id) {
+				entry->thread_num++;
+			}
+		} else {
+			cpu_topology[cpu].thread_id  = -1;
+			cpu_topology[cpu].core_id    = topology_id;
+		}
+		topology_id = find_acpi_cpu_topology_cluster(cpu);
+		cpu_topology[cpu].cluster_id = topology_id;
+		topology_id = find_acpi_cpu_topology_package(cpu);
+		cpu_topology[cpu].package_id = topology_id;
+	}
+
+	/*
+	 * This is a short loop since the number of XArray elements is the
+	 * number of heterogeneous CPU clusters. On a homogeneous system
+	 * there's only one entry in the XArray.
+	 */
+	xa_for_each(&hetero_cpu, hetero_id, entry) {
+		max_smt_thread_num = max(max_smt_thread_num, entry->thread_num);
+		xa_erase(&hetero_cpu, hetero_id);
+		kfree(entry);
+	}
+
+	cpu_smt_set_num_threads(max_smt_thread_num, max_smt_thread_num);
+	xa_destroy(&hetero_cpu);
 	return 0;
 }
 
-#if defined(CONFIG_ARM64) || defined(CONFIG_RISCV)
 void __init init_cpu_topology(void)
 {
 	int cpu, ret;

drivers/base/base.h

@@ -85,6 +85,18 @@ struct driver_private {
 };
 #define to_driver(obj) container_of(obj, struct driver_private, kobj)
 
+#ifdef CONFIG_RUST
+/**
+ * struct driver_type - Representation of a Rust driver type.
+ */
+struct driver_type {
+	/**
+	 * @id: Representation of core::any::TypeId.
+	 */
+	u8 id[16];
+} __packed;
+#endif
+
 /**
  * struct device_private - structure to hold the private to the driver core portions of the device structure.
  *
@@ -100,6 +112,7 @@ struct driver_private {
  * @async_driver - pointer to device driver awaiting probe via async_probe
  * @device - pointer back to the struct device that this structure is
  * associated with.
+ * @driver_type - The type of the bound Rust driver.
  * @dead - This device is currently either in the process of or has been
  *	removed from the system. Any asynchronous events scheduled for this
  *	device should exit without taking any action.
@@ -116,6 +129,9 @@ struct device_private {
 	const struct device_driver *async_driver;
 	char *deferred_probe_reason;
 	struct device *device;
+#ifdef CONFIG_RUST
+	struct driver_type driver_type;
+#endif
 	u8 dead:1;
 };
 #define to_device_private_parent(obj)	\

drivers/base/bus.c

@@ -533,8 +533,7 @@ void bus_probe_device(struct device *dev)
 	if (!sp)
 		return;
 
-	if (sp->drivers_autoprobe)
-		device_initial_probe(dev);
+	device_initial_probe(dev);
 
 	mutex_lock(&sp->mutex);
 	list_for_each_entry(sif, &sp->interfaces, node)

drivers/base/core.c

@@ -4138,7 +4138,7 @@ int __init devices_init(void)
 	sysfs_dev_char_kobj = kobject_create_and_add("char", dev_kobj);
 	if (!sysfs_dev_char_kobj)
 		goto char_kobj_err;
-	device_link_wq = alloc_workqueue("device_link_wq", 0, 0);
+	device_link_wq = alloc_workqueue("device_link_wq", WQ_PERCPU, 0);
 	if (!device_link_wq)
 		goto wq_err;