Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751660AbaKFQnn (ORCPT ); Thu, 6 Nov 2014 11:43:43 -0500 Received: from bh-25.webhostbox.net ([208.91.199.152]:56041 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751603AbaKFQnj (ORCPT ); Thu, 6 Nov 2014 11:43:39 -0500 From: Guenter Roeck To: linux-kernel@vger.kernel.org Cc: linux-pm@vger.kernel.org, Guenter Roeck , Alan Cox , Alexander Graf , Andrew Morton , Geert Uytterhoeven , Heiko Stuebner , Lee Jones , Len Brown , Linus Torvalds , Pavel Machek , "Rafael J. Wysocki" , Romain Perier Subject: [PATCH v5 00/48] kernel: Add support for power-off handler call chain Date: Thu, 6 Nov 2014 08:42:44 -0800 Message-Id: <1415292213-28652-1-git-send-email-linux@roeck-us.net> X-Mailer: git-send-email 1.9.1 X-Authenticated_sender: guenter@roeck-us.net X-OutGoing-Spam-Status: No, score=-1.0 X-CTCH-PVer: 0000001 X-CTCH-Spam: Unknown X-CTCH-VOD: Unknown X-CTCH-Flags: 0 X-CTCH-RefID: str=0001.0A020209.545BA53A.017B,ss=1,re=0.001,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0 X-CTCH-Score: 0.001 X-CTCH-ScoreCust: 0.000 X-CTCH-Rules: C_4847, X-CTCH-SenderID: linux@roeck-us.net X-CTCH-SenderID-Flags: 0 X-CTCH-SenderID-TotalMessages: 1 X-CTCH-SenderID-TotalSpam: 0 X-CTCH-SenderID-TotalSuspected: 0 X-CTCH-SenderID-TotalConfirmed: 0 X-CTCH-SenderID-TotalBulk: 0 X-CTCH-SenderID-TotalVirus: 0 X-CTCH-SenderID-TotalRecipients: 0 X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - bh-25.webhostbox.net X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - roeck-us.net X-Get-Message-Sender-Via: bh-25.webhostbox.net: mailgid no entry from get_relayhosts_entry X-Source: X-Source-Args: X-Source-Dir: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Various drivers implement architecture and/or device specific means to remove power from the system. For the most part, those drivers set the global variable pm_power_off to point to a function within the driver. This mechanism has a number of drawbacks. Typically only one means to remove power is supported (at least if pm_power_off is used). At least in theory there can be multiple means to remove power, some of which may be less desirable. For example, one mechanism might power off the entire system through an I/O port or gpio pin, while another might power off a board by disabling its power controller. Other mechanisms may really just execute a restart sequence or drop into the ROM monitor, or put the CPU into sleep mode. Using pm_power_off can also be racy if the function pointer is set from a driver built as module, as the driver may be in the process of being unloaded when pm_power_off is called. If there are multiple power-off handlers in the system, removing a module with such a handler may inadvertently reset the pointer to pm_power_off to NULL, leaving the system with no means to remove power. Introduce a system power-off handler call chain to solve the described problems. This call chain is expected to be executed from the architecture specific machine_power_off() function. Drivers providing system power-off functionality are expected to register with this call chain. By using the priority field in the notifier block, callers can control power-off handler execution sequence and thus ensure that the power-off handler with the optimal capabilities to remove power for a given system is called first. A call chain instead of a single call to the highest priority handler is used to provide fallback: If multiple power-off handlers are installed, all handlers will be called until one actually succeeds to power off the system. Patch 01/48 implements the power-off handler API. Patches 02/48 to 04/48 are cleanup patches to prepare for the move of pm_power_off to a common location. Patches 05/48 to 07/48 remove references to pm_power_off from devicetree bindings descriptions. Patch 08/48 moves the pm_power_off variable from architecture code to kernel/reboot.c. Patches 09/48 to 34/48 convert various drivers to register with the kernel power-off handler instead of setting pm_power_off directly. Patches 35/48 to 47/48 do the same for architecture code. Patch 48/48 finally removes pm_power_off. For the most part, the individual patches include explanations why specific priorities were chosen, at least if the selected priority is not the default priority. Subsystem and architecture maintainers are encouraged to have a look at the selected priorities and suggest improvements. I ran the final code through my normal build and qemu tests. Results are available at http://server.roeck-us.net:8010/builders in the 'poweroff-handler' column. I also built all available configurations for arm, mips, powerpc, m68k, and sh architectures. The series is available in branch poweroff-handler of my repository at git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging.git. It is based on 3.18-rc3 plus the power-off tracking branch from git://git.kernel.org/pub/scm/linux/kernel/git/mpe/linux.git (to merge powerpc related power-off changes). A note on Cc: In the initial submission I had way too many Cc:, causing the patchset to be treated as spam by many mailers and mailing list handlers, which of course defeated the purpose. Starting with v3, the distribution list has been cut down significantly. Copied mailing lists and individuals are for the most part generated from the output of get_maintainer.pl for each individual patch. My apologies to anyone I may have failed to copy; if you believe that some additional individuals or mailing lists should be copied on the entire series or on individual patches, please let me know. Merge plan is to send the entire series directly to Linus during the next commit window, except for the last patch. The last patch would then be part of another pull request after -rc1, which would include any changes necessary due to newly merged power-off handling code. v5: - Rebased series to v3.18-rc3 - Merge remote-tracking branch 'power/topic/pm-power-off' from git://git.kernel.org/pub/scm/linux/kernel/git/mpe/linux.git and implement powerpc conversion (patch 41/48). v4: - Do not use notifiers but internal functions and data structures to manage the list of power-off handlers. Drop unused parameters from callbacks, and make the power-off function type void. Code to manage and walk the list of callbacks was derived from notifier.c. Note that only patch 01/47 was sent for review of this version. v3: - Rebased series to v3.18-rc2. - Do not hold any locks while executing the power-off call chain. This ensures that power-off handlers are executed in the state selected by the machine_power_off function for a given architecture, ie without changing the current semantics of power-off callbacks and machine_power_off functions. Power-off handler registration and de-registration is handled in atomic context with interrupts disabled to ensure that those functions are not interrupted by code which powers off the system. - Use [xxx_]power_off[_xxx] instead of [xxx_]poweroff[_xxx] for newly introduced function and variable names. - Use power-off instead of poweroff in descriptive text and comments. - Replace POWEROFF_PRIORITY_xxx with POWER_OFF_PRIORITY_xxx - Use ACPI: instead of acpi: for messages in acpi code. v2: - Rebased series to v3.18-rc1. - Use raw notifier with spinlock protection instead of atomic notifiers, since some power-off handlers need to have interrupts enabled. - Renamed API functions from _poweroff to _power_off. - Added various Acks. - Build tested all configurations for arm, powerpc, and mips architectures. - Fixed two compile errors in mips patch. - Replaced dev_err and pr_err with dev_warn and pr_warn if an error is not fatal. - Provide managed resources API and use where appropriate. - Provide and use definitions for standard priorities. - Added patches to convert newly introduced power-off handlers. - Various minor changes. v1 (from RFC): - Move API to new file kernel/power/power_off_handler.c. - Move pm_power_off pointer to kernel/power/power_off_handler.c. Call pm_power_off from do_kernel_power_off, and only call do_kernel_power_off from architecture code instead of calling both pm_power_off and do_kernel_power_off. - Provide additional API function register_power_off_handler_simple to simplify conversion of architecture code. - Provide additional API function have_kernel_power_off to check if a power-off handler was installed. - Convert all drivers and architecture code to use the new API. - Remove pm_power_off as last patch of the series. Cc: Alan Cox Cc: Alexander Graf Cc: Andrew Morton Cc: Geert Uytterhoeven cc: Heiko Stuebner Cc: Lee Jones Cc: Len Brown Cc: Linus Torvalds Cc: Pavel Machek Cc: Rafael J. Wysocki Cc: Romain Perier -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/