kernel/drivers/i2c/busses/i2c-i801.c, branch linux-6.12.y

i2c: i801: Revert "i2c: i801: replace acpi_lock with I2C bus lock"

2026-03-13T16:20:43Z

[ Upstream commit cfc69c2e6c699c96949f7b0455195b0bfb7dc715 ] This reverts commit f707d6b9e7c18f669adfdb443906d46cfbaaa0c1. Under rare circumstances, multiple udev threads can collect i801 device info on boot and walk i801_acpi_io_handler somewhat concurrently. The first will note the area is reserved by acpi to prevent further touches. This ultimately causes the area to be deregistered. The second will enter i801_acpi_io_handler after the area is unregistered but before a check can be made that the area is unregistered. i2c_lock_bus relies on the now unregistered area containing lock_ops to lock the bus. The end result is a kernel panic on boot with the following backtrace; [ 14.971872] ioatdma 0000:09:00.2: enabling device (0100 -> 0102) [ 14.971873] BUG: kernel NULL pointer dereference, address: 0000000000000000 [ 14.971880] #PF: supervisor read access in kernel mode [ 14.971884] #PF: error_code(0x0000) - not-present page [ 14.971887] PGD 0 P4D 0 [ 14.971894] Oops: 0000 [#1] PREEMPT SMP PTI [ 14.971900] CPU: 5 PID: 956 Comm: systemd-udevd Not tainted 5.14.0-611.5.1.el9_7.x86_64 #1 [ 14.971905] Hardware name: XXXXXXXXXXXXXXXXXXXXXXX BIOS 1.20.10.SV91 01/30/2023 [ 14.971908] RIP: 0010:i801_acpi_io_handler+0x2d/0xb0 [i2c_i801] [ 14.971929] Code: 00 00 49 8b 40 20 41 57 41 56 4d 8b b8 30 04 00 00 49 89 ce 41 55 41 89 d5 41 54 49 89 f4 be 02 00 00 00 55 4c 89 c5 53 89 fb <48> 8b 00 4c 89 c7 e8 18 61 54 e9 80 bd 80 04 00 00 00 75 09 4c 3b [ 14.971933] RSP: 0018:ffffbaa841483838 EFLAGS: 00010282 [ 14.971938] RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff9685e01ba568 [ 14.971941] RDX: 0000000000000008 RSI: 0000000000000002 RDI: 0000000000000000 [ 14.971944] RBP: ffff9685ca22f028 R08: ffff9685ca22f028 R09: ffff9685ca22f028 [ 14.971948] R10: 000000000000000b R11: 0000000000000580 R12: 0000000000000580 [ 14.971951] R13: 0000000000000008 R14: ffff9685e01ba568 R15: ffff9685c222f000 [ 14.971954] FS: 00007f8287c0ab40(0000) GS:ffff96a47f940000(0000) knlGS:0000000000000000 [ 14.971959] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 14.971963] CR2: 0000000000000000 CR3: 0000000168090001 CR4: 00000000003706f0 [ 14.971966] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 14.971968] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 14.971972] Call Trace: [ 14.971977] [ 14.971981] ? show_trace_log_lvl+0x1c4/0x2df [ 14.971994] ? show_trace_log_lvl+0x1c4/0x2df [ 14.972003] ? acpi_ev_address_space_dispatch+0x16e/0x3c0 [ 14.972014] ? __die_body.cold+0x8/0xd [ 14.972021] ? page_fault_oops+0x132/0x170 [ 14.972028] ? exc_page_fault+0x61/0x150 [ 14.972036] ? asm_exc_page_fault+0x22/0x30 [ 14.972045] ? i801_acpi_io_handler+0x2d/0xb0 [i2c_i801] [ 14.972061] acpi_ev_address_space_dispatch+0x16e/0x3c0 [ 14.972069] ? __pfx_i801_acpi_io_handler+0x10/0x10 [i2c_i801] [ 14.972085] acpi_ex_access_region+0x5b/0xd0 [ 14.972093] acpi_ex_field_datum_io+0x73/0x2e0 [ 14.972100] acpi_ex_read_data_from_field+0x8e/0x230 [ 14.972106] acpi_ex_resolve_node_to_value+0x23d/0x310 [ 14.972114] acpi_ds_evaluate_name_path+0xad/0x110 [ 14.972121] acpi_ds_exec_end_op+0x321/0x510 [ 14.972127] acpi_ps_parse_loop+0xf7/0x680 [ 14.972136] acpi_ps_parse_aml+0x17a/0x3d0 [ 14.972143] acpi_ps_execute_method+0x137/0x270 [ 14.972150] acpi_ns_evaluate+0x1f4/0x2e0 [ 14.972158] acpi_evaluate_object+0x134/0x2f0 [ 14.972164] acpi_evaluate_integer+0x50/0xe0 [ 14.972173] ? vsnprintf+0x24b/0x570 [ 14.972181] acpi_ac_get_state.part.0+0x23/0x70 [ 14.972189] get_ac_property+0x4e/0x60 [ 14.972195] power_supply_show_property+0x90/0x1f0 [ 14.972205] add_prop_uevent+0x29/0x90 [ 14.972213] power_supply_uevent+0x109/0x1d0 [ 14.972222] dev_uevent+0x10e/0x2f0 [ 14.972228] uevent_show+0x8e/0x100 [ 14.972236] dev_attr_show+0x19/0x40 [ 14.972246] sysfs_kf_seq_show+0x9b/0x100 [ 14.972253] seq_read_iter+0x120/0x4b0 [ 14.972262] ? selinux_file_permission+0x106/0x150 [ 14.972273] vfs_read+0x24f/0x3a0 [ 14.972284] ksys_read+0x5f/0xe0 [ 14.972291] do_syscall_64+0x5f/0xe0 ... The kernel panic is mitigated by setting limiting the count of udev children to 1. Revert to using the acpi_lock to continue protecting marking the area as owned by firmware without relying on a lock in a potentially unmapped region of memory. Fixes: f707d6b9e7c1 ("i2c: i801: replace acpi_lock with I2C bus lock") Signed-off-by: Charles Haithcock [wsa: added Fixes-tag and updated comment stating the importance of the lock] Signed-off-by: Wolfram Sang Signed-off-by: Sasha Levin

i2c: i801: Hide Intel Birch Stream SoC TCO WDT

2025-09-19T14:35:45Z

commit 664596bd98bb251dd417dfd3f9b615b661e1e44a upstream. Hide the Intel Birch Stream SoC TCO WDT feature since it was removed. On platforms with PCH TCO WDT, this redundant device might be rendering errors like this: [ 28.144542] sysfs: cannot create duplicate filename '/bus/platform/devices/iTCO_wdt' Fixes: 8c56f9ef25a3 ("i2c: i801: Add support for Intel Birch Stream SoC") Link: https://bugzilla.kernel.org/show_bug.cgi?id=220320 Signed-off-by: Chiasheng Lee Cc: # v6.7+ Reviewed-by: Mika Westerberg Reviewed-by: Jarkko Nikula Signed-off-by: Andi Shyti Link: https://lore.kernel.org/r/20250901125943.916522-1-chiasheng.lee@linux.intel.com Signed-off-by: Greg Kroah-Hartman

i2c: i801: Add support for Intel Panther Lake

2024-12-14T19:03:55Z

[ Upstream commit bd492b58371295d3ae26162b9666be584abad68a ] Add SMBus PCI IDs on Intel Panther Lake-P and -U. Signed-off-by: Jarkko Nikula Signed-off-by: Andi Shyti Signed-off-by: Sasha Levin

i2c: i801: Use a different adapter-name for IDF adapters

2024-09-09T22:36:56Z

On chipsets with a second 'Integrated Device Function' SMBus controller use a different adapter-name for the second IDF adapter. This allows platform glue code which is looking for the primary i801 adapter to manually instantiate i2c_clients on to differentiate between the 2. This allows such code to find the primary i801 adapter by name, without needing to duplicate the PCI-ids to feature-flags mapping from i2c-i801.c. Reviewed-by: Pali Rohár Signed-off-by: Hans de Goede Acked-by: Wolfram Sang Signed-off-by: Andi Shyti

i2c: i801: reword according to newest specification

2024-07-11T13:14:11Z

Change the wording of this driver wrt. the newest I2C v7 and SMBus 3.2 specifications and replace "master/slave" with more appropriate terms. Signed-off-by: Wolfram Sang Reviewed-by: Andi Shyti Signed-off-by: Andi Shyti

i2c: i801: Add support for Intel Arrow Lake-H

2024-07-08T22:46:05Z

Add SMBus PCI ID on Intel Arrow Lake-H. Signed-off-by: Jarkko Nikula Signed-off-by: Andi Shyti

i2c: i801: remove printout on handled timeouts

2024-05-05T22:56:47Z

I2C and SMBus timeouts are not something the user needs to be informed about on controller level. The client driver may know if that really is a problem and give more detailed information to the user. The controller should just pass this information upwards. Remove the printout and turn the SMBus-specific termination message to debug. Signed-off-by: Wolfram Sang Reviewed-by: Jean Delvare Signed-off-by: Andi Shyti

i2c: i801: Annotate apanel_addr as __ro_after_init

2024-05-05T22:56:31Z

Annotate this variable as __ro_after_init to protect it from being overwritten later. Signed-off-by: Heiner Kallweit Signed-off-by: Andi Shyti

i2c: i801: Remove usage of I2C_CLASS_SPD

2024-05-05T22:56:13Z

Only remaining client driver supporting I2C_CLASS_SPD is jc42. This type of thermal sensor can be found on several DDR3/DDR4 modules. i2c_register_spd() instantiates also such thermal sensor i2c devices. Since 893fef0bc6aa ("i2c: i801: Call i2c_register_spd for muxed child segments") i2c_register_spd() is called also for the remaining use case, systems with muxed SMBUS segments for SPD EEPROMs. Therefore I2C_CLASS_SPD class-based instantiation isn't needed any longer in this driver, so remove it. Signed-off-by: Heiner Kallweit Signed-off-by: Andi Shyti

i2c: i801: Fix missing Kconfig dependency

2024-05-05T22:55:41Z

The original change adds usage of i2c_root_adapter(), which is implemented in i2c-mux.c. Therefore we can't use the multiplexing if I2C_I801=y and I2C_MUX=m. Handling the dependencies in the code would become unnecessarily complex, therefore create a new config symbol. Fixes: 893fef0bc6aa ("i2c: i801: Call i2c_register_spd for muxed child segments") Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202404042206.MjAQC32x-lkp@intel.com/ Signed-off-by: Heiner Kallweit Reviewed-by: Wolfram Sang Signed-off-by: Andi Shyti