diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/ABI/stable/sysfs-acpi-pmprofile | 22 | ||||
| -rw-r--r-- | Documentation/ABI/testing/sysfs-bus-pci-devices-cciss | 7 | ||||
| -rw-r--r-- | Documentation/DocBook/mtdnand.tmpl | 19 | ||||
| -rw-r--r-- | Documentation/blockdev/cciss.txt | 10 | ||||
| -rw-r--r-- | Documentation/devicetree/bindings/mtd/atmel-dataflash.txt | 14 | ||||
| -rw-r--r-- | Documentation/devicetree/bindings/powerpc/fsl/board.txt | 30 | ||||
| -rw-r--r-- | Documentation/devicetree/bindings/powerpc/fsl/dcsr.txt | 395 | ||||
| -rw-r--r-- | Documentation/devicetree/bindings/powerpc/fsl/msi-pic.txt | 42 | ||||
| -rw-r--r-- | Documentation/oops-tracing.txt | 2 | ||||
| -rw-r--r-- | Documentation/power/freezing-of-tasks.txt | 8 | ||||
| -rw-r--r-- | Documentation/power/runtime_pm.txt | 10 | ||||
| -rw-r--r-- | Documentation/watchdog/convert_drivers_to_kernel_api.txt | 195 |
12 files changed, 720 insertions, 34 deletions
diff --git a/Documentation/ABI/stable/sysfs-acpi-pmprofile b/Documentation/ABI/stable/sysfs-acpi-pmprofile new file mode 100644 index 00000000000..964c7a8afb2 --- /dev/null +++ b/Documentation/ABI/stable/sysfs-acpi-pmprofile @@ -0,0 +1,22 @@ +What: /sys/firmware/acpi/pm_profile +Date: 03-Nov-2011 +KernelVersion: v3.2 +Contact: linux-acpi@vger.kernel.org +Description: The ACPI pm_profile sysfs interface exports the platform + power management (and performance) requirement expectations + as provided by BIOS. The integer value is directly passed as + retrieved from the FADT ACPI table. +Values: For possible values see ACPI specification: + 5.2.9 Fixed ACPI Description Table (FADT) + Field: Preferred_PM_Profile + + Currently these values are defined by spec: + 0 Unspecified + 1 Desktop + 2 Mobile + 3 Workstation + 4 Enterprise Server + 5 SOHO Server + 6 Appliance PC + 7 Performance Server + >7 Reserved diff --git a/Documentation/ABI/testing/sysfs-bus-pci-devices-cciss b/Documentation/ABI/testing/sysfs-bus-pci-devices-cciss index f5bb0a3bb8c..53d99edd1d7 100644 --- a/Documentation/ABI/testing/sysfs-bus-pci-devices-cciss +++ b/Documentation/ABI/testing/sysfs-bus-pci-devices-cciss @@ -71,3 +71,10 @@ Description: Value of 1 indicates the controller can honor the reset_devices a dump device, as kdump requires resetting the device in order to work reliably. +Where: /sys/bus/pci/devices/<dev>/ccissX/transport_mode +Date: July 2011 +Kernel Version: 3.0 +Contact: iss_storagedev@hp.com +Description: Value of "simple" indicates that the controller has been placed + in "simple mode". Value of "performant" indicates that the + controller has been placed in "performant mode". diff --git a/Documentation/DocBook/mtdnand.tmpl b/Documentation/DocBook/mtdnand.tmpl index 17910e2052a..0c674be0d3c 100644 --- a/Documentation/DocBook/mtdnand.tmpl +++ b/Documentation/DocBook/mtdnand.tmpl @@ -572,7 +572,7 @@ static void board_select_chip (struct mtd_info *mtd, int chip) </para> <para> The simplest way to activate the FLASH based bad block table support - is to set the option NAND_USE_FLASH_BBT in the option field of + is to set the option NAND_BBT_USE_FLASH in the bbt_option field of the nand chip structure before calling nand_scan(). For AG-AND chips is this done by default. This activates the default FLASH based bad block table functionality @@ -773,20 +773,6 @@ struct nand_oobinfo { done according to the default builtin scheme. </para> </sect2> - <sect2 id="User_space_placement_selection"> - <title>User space placement selection</title> - <para> - All non ecc functions like mtd->read and mtd->write use an internal - structure, which can be set by an ioctl. This structure is preset - to the autoplacement default. - <programlisting> - ioctl (fd, MEMSETOOBSEL, oobsel); - </programlisting> - oobsel is a pointer to a user supplied structure of type - nand_oobconfig. The contents of this structure must match the - criteria of the filesystem, which will be used. See an example in utils/nandwrite.c. - </para> - </sect2> </sect1> <sect1 id="Spare_area_autoplacement_default"> <title>Spare area autoplacement default schemes</title> @@ -1158,9 +1144,6 @@ in this page</entry> These constants are defined in nand.h. They are ored together to describe the functionality. <programlisting> -/* Use a flash based bad block table. This option is parsed by the - * default bad block table function (nand_default_bbt). */ -#define NAND_USE_FLASH_BBT 0x00010000 /* The hw ecc generator provides a syndrome instead a ecc value on read * This can only work if we have the ecc bytes directly behind the * data bytes. Applies for DOC and AG-AND Renesas HW Reed Solomon generators */ diff --git a/Documentation/blockdev/cciss.txt b/Documentation/blockdev/cciss.txt index c00c6a5ab21..71464e09ec1 100644 --- a/Documentation/blockdev/cciss.txt +++ b/Documentation/blockdev/cciss.txt @@ -78,6 +78,16 @@ The device naming scheme is: /dev/cciss/c1d1p2 Controller 1, disk 1, partition 2 /dev/cciss/c1d1p3 Controller 1, disk 1, partition 3 +CCISS simple mode support +------------------------- + +The "cciss_simple_mode=1" boot parameter may be used to prevent the driver +from putting the controller into "performant" mode. The difference is that +with simple mode, each command completion requires an interrupt, while with +"performant mode" (the default, and ordinarily better performing) it is +possible to have multiple command completions indicated by a single +interrupt. + SCSI tape drive and medium changer support ------------------------------------------ diff --git a/Documentation/devicetree/bindings/mtd/atmel-dataflash.txt b/Documentation/devicetree/bindings/mtd/atmel-dataflash.txt new file mode 100644 index 00000000000..ef66ddd01da --- /dev/null +++ b/Documentation/devicetree/bindings/mtd/atmel-dataflash.txt @@ -0,0 +1,14 @@ +* Atmel Data Flash + +Required properties: +- compatible : "atmel,<model>", "atmel,<series>", "atmel,dataflash". + +Example: + +flash@1 { + #address-cells = <1>; + #size-cells = <1>; + compatible = "atmel,at45db321d", "atmel,at45", "atmel,dataflash"; + spi-max-frequency = <25000000>; + reg = <1>; +}; diff --git a/Documentation/devicetree/bindings/powerpc/fsl/board.txt b/Documentation/devicetree/bindings/powerpc/fsl/board.txt index 39e941515a3..380914e965e 100644 --- a/Documentation/devicetree/bindings/powerpc/fsl/board.txt +++ b/Documentation/devicetree/bindings/powerpc/fsl/board.txt @@ -1,3 +1,8 @@ +Freescale Reference Board Bindings + +This document describes device tree bindings for various devices that +exist on some Freescale reference boards. + * Board Control and Status (BCSR) Required properties: @@ -12,25 +17,26 @@ Example: reg = <f8000000 8000>; }; -* Freescale on board FPGA +* Freescale on-board FPGA This is the memory-mapped registers for on board FPGA. Required properities: -- compatible : should be "fsl,fpga-pixis". -- reg : should contain the address and the length of the FPPGA register - set. +- compatible: should be a board-specific string followed by a string + indicating the type of FPGA. Example: + "fsl,<board>-fpga", "fsl,fpga-pixis" +- reg: should contain the address and the length of the FPGA register set. - interrupt-parent: should specify phandle for the interrupt controller. -- interrupts : should specify event (wakeup) IRQ. +- interrupts: should specify event (wakeup) IRQ. -Example (MPC8610HPCD): +Example (P1022DS): - board-control@e8000000 { - compatible = "fsl,fpga-pixis"; - reg = <0xe8000000 32>; - interrupt-parent = <&mpic>; - interrupts = <8 8>; - }; + board-control@3,0 { + compatible = "fsl,p1022ds-fpga", "fsl,fpga-ngpixis"; + reg = <3 0 0x30>; + interrupt-parent = <&mpic>; + interrupts = <8 8 0 0>; + }; * Freescale BCSR GPIO banks diff --git a/Documentation/devicetree/bindings/powerpc/fsl/dcsr.txt b/Documentation/devicetree/bindings/powerpc/fsl/dcsr.txt new file mode 100644 index 00000000000..9d54eb5a295 --- /dev/null +++ b/Documentation/devicetree/bindings/powerpc/fsl/dcsr.txt @@ -0,0 +1,395 @@ +=================================================================== +Debug Control and Status Register (DCSR) Binding +Copyright 2011 Freescale Semiconductor Inc. + +NOTE: The bindings described in this document are preliminary and subject +to change. Some of the compatible strings that contain only generic names +may turn out to be inappropriate, or need additional properties to describe +the integration of the block with the rest of the chip. + +===================================================================== +Debug Control and Status Register Memory Map + +Description + +This node defines the base address and range for the +defined DCSR Memory Map. Child nodes will describe the individual +debug blocks defined within this memory space. + +PROPERTIES + + - compatible + Usage: required + Value type: <string> + Definition: Must include "fsl,dcsr" and "simple-bus". + The DCSR space exists in the memory-mapped bus. + + - #address-cells + Usage: required + Value type: <u32> + Definition: A standard property. Defines the number of cells + or representing physical addresses in child nodes. + + - #size-cells + Usage: required + Value type: <u32> + Definition: A standard property. Defines the number of cells + or representing the size of physical addresses in + child nodes. + + - ranges + Usage: required + Value type: <prop-encoded-array> + Definition: A standard property. Specifies the physical address + range of the DCSR space. + +EXAMPLE + dcsr: dcsr@f00000000 { + #address-cells = <1>; + #size-cells = <1>; + compatible = "fsl,dcsr", "simple-bus"; + ranges = <0x00000000 0xf 0x00000000 0x01008000>; + }; + +===================================================================== +Event Processing Unit + +This node represents the region of DCSR space allocated to the EPU + +PROPERTIES + + - compatible + Usage: required + Value type: <string> + Definition: Must include "fsl,dcsr-epu" + + - interrupts + Usage: required + Value type: <prop_encoded-array> + Definition: Specifies the interrupts generated by the EPU. + The value of the interrupts property consists of three + interrupt specifiers. The format of the specifier is defined + by the binding document describing the node's interrupt parent. + + The EPU counters can be configured to assert the performance + monitor interrupt signal based on either counter overflow or value + match. Which counter asserted the interrupt is captured in an EPU + Counter Interrupt Status Register (EPCPUISR). + + The EPU unit can also be configured to assert either or both of + two interrupt signals based on debug event sources within the SoC. + The interrupt signals are epu_xt_int0 and epu_xt_int1. + Which event source asserted the interrupt is captured in an EPU + Interrupt Status Register (EPISR0,EPISR1). + + Interrupt numbers are lised in order (perfmon, event0, event1). + + - interrupt-parent + Usage: required + Value type: <phandle> + Definition: A single <phandle> value that points + to the interrupt parent to which the child domain + is being mapped. Value must be "&mpic" + + - reg + Usage: required + Value type: <prop-encoded-array> + Definition: A standard property. Specifies the physical address + offset and length of the DCSR space registers of the device + configuration block. + +EXAMPLE + dcsr-epu@0 { + compatible = "fsl,dcsr-epu"; + interrupts = <52 2 0 0 + 84 2 0 0 + 85 2 0 0>; + interrupt-parent = <&mpic>; + reg = <0x0 0x1000>; + }; + +======================================================================= +Nexus Port Controller + +This node represents the region of DCSR space allocated to the NPC + +PROPERTIES + + - compatible + Usage: required + Value type: <string> + Definition: Must include "fsl,dcsr-npc" + + - reg + Usage: required + Value type: <prop-encoded-array> + Definition: A standard property. Specifies the physical address + offset and length of the DCSR space registers of the device + configuration block. + The Nexus Port controller occupies two regions in the DCSR space + with distinct functionality. + + The first register range describes the Nexus Port Controller + control and status registers. + + The second register range describes the Nexus Port Controller + internal trace buffer. The NPC trace buffer is a small memory buffer + which stages the nexus trace data for transmission via the Aurora port + or to a DDR based trace buffer. In some configurations the NPC trace + buffer can be the only trace buffer used. + + +EXAMPLE + dcsr-npc { + compatible = "fsl,dcsr-npc"; + reg = <0x1000 0x1000 0x1000000 0x8000>; + }; + +======================================================================= +Nexus Concentrator + +This node represents the region of DCSR space allocated to the NXC + +PROPERTIES + + - compatible + Usage: required + Value type: <string> + Definition: Must include "fsl,dcsr-nxc" + + - reg + Usage: required + Value type: <prop-encoded-array> + Definition: A standard property. Specifies the physical address + offset and length of the DCSR space registers of the device + configuration block. + +EXAMPLE + dcsr-nxc@2000 { + compatible = "fsl,dcsr-nxc"; + reg = <0x2000 0x1000>; + }; +======================================================================= +CoreNet Debug Controller + +This node represents the region of DCSR space allocated to +the CoreNet Debug controller. + +PROPERTIES + + - compatible + Usage: required + Value type: <string> + Definition: Must include "fsl,dcsr-corenet" + + - reg + Usage: required + Value type: <prop-encoded-array> + Definition: A standard property. Specifies the physical address + offset and length of the DCSR space registers of the device + configuration block. + The CoreNet Debug controller occupies two regions in the DCSR space + with distinct functionality. + + The first register range describes the CoreNet Debug Controller + functionalty to perform transaction and transaction attribute matches. + + The second register range describes the CoreNet Debug Controller + functionalty to trigger event notifications and debug traces. + +EXAMPLE + dcsr-corenet { + compatible = "fsl,dcsr-corenet"; + reg = <0x8000 0x1000 0xB0000 0x1000>; + }; + +======================================================================= +Data Path Debug controller + +This node represents the region of DCSR space allocated to +the DPAA Debug Controller. This controller controls debug configuration +for the QMAN and FMAN blocks. + +PROPERTIES + + - compatible + Usage: required + Value type: <string> + Definition: Must include both an identifier specific to the SoC + or Debug IP of the form "fsl,<soc>-dcsr-dpaa" in addition to the + generic compatible string "fsl,dcsr-dpaa". + + - reg + Usage: required + Value type: <prop-encoded-array> + Definition: A standard property. Specifies the physical address + offset and length of the DCSR space registers of the device + configuration block. + +EXAMPLE + dcsr-dpaa@9000 { + compatible = "fsl,p4080-dcsr-dpaa", "fsl,dcsr-dpaa"; + reg = <0x9000 0x1000>; + }; + +======================================================================= +OCeaN Debug controller + +This node represents the region of DCSR space allocated to +the OCN Debug Controller. + +PROPERTIES + + - compatible + Usage: required + Value type: <string> + Definition: Must include both an identifier specific to the SoC + or Debug IP of the form "fsl,<soc>-dcsr-ocn" in addition to the + generic compatible string "fsl,dcsr-ocn". + + - reg + Usage: required + Value type: <prop-encoded-array> + Definition: A standard property. Specifies the physical address + offset and length of the DCSR space registers of the device + configuration block. + +EXAMPLE + dcsr-ocn@11000 { + compatible = "fsl,p4080-dcsr-ocn", "fsl,dcsr-ocn"; + reg = <0x11000 0x1000>; + }; + +======================================================================= +DDR Controller Debug controller + +This node represents the region of DCSR space allocated to +the OCN Debug Controller. + +PROPERTIES + + - compatible + Usage: required + Value type: <string> + Definition: Must include "fsl,dcsr-ddr" + + - dev-handle + Usage: required + Definition: A phandle to associate this debug node with its + component controller. + + - reg + Usage: required + Value type: <prop-encoded-array> + Definition: A standard property. Specifies the physical address + offset and length of the DCSR space registers of the device + configuration block. + +EXAMPLE + dcsr-ddr@12000 { + compatible = "fsl,dcsr-ddr"; + dev-handle = <&ddr1>; + reg = <0x12000 0x1000>; + }; + +======================================================================= +Nexus Aurora Link Controller + +This node represents the region of DCSR space allocated to +the NAL Controller. + +PROPERTIES + + - compatible + Usage: required + Value type: <string> + Definition: Must include both an identifier specific to the SoC + or Debug IP of the form "fsl,<soc>-dcsr-nal" in addition to the + generic compatible string "fsl,dcsr-nal". + + - reg + Usage: required + Value type: <prop-encoded-array> + Definition: A standard property. Specifies the physical address + offset and length of the DCSR space registers of the device + configuration block. + +EXAMPLE + dcsr-nal@18000 { + compatible = "fsl,p4080-dcsr-nal", "fsl,dcsr-nal"; + reg = <0x18000 0x1000>; + }; + + +======================================================================= +Run Control and Power Management + +This node represents the region of DCSR space allocated to +the RCPM Debug Controller. This functionlity is limited to the +control the debug operations of the SoC and cores. + +PROPERTIES + + - compatible + Usage: required + Value type: <string> + Definition: Must include both an identifier specific to the SoC + or Debug IP of the form "fsl,<soc>-dcsr-rcpm" in addition to the + generic compatible string "fsl,dcsr-rcpm". + + - reg + Usage: required + Value type: <prop-encoded-array> + Definition: A standard property. Specifies the physical address + offset and length of the DCSR space registers of the device + configuration block. + +EXAMPLE + dcsr-rcpm@22000 { + compatible = "fsl,p4080-dcsr-rcpm", "fsl,dcsr-rcpm"; + reg = <0x22000 0x1000>; + }; + +======================================================================= +Core Service Bridge Proxy + +This node represents the region of DCSR space allocated to +the Core Service Bridge Proxies. +There is one Core Service Bridge Proxy device for each CPU in the system. +This functionlity provides access to the debug operations of the CPU. + +PROPERTIES + + - compatible + Usage: required + Value type: <string> + Definition: Must include both an identifier specific to the cpu + of the form "fsl,dcsr-<cpu>-sb-proxy" in addition to the + generic compatible string "fsl,dcsr-cpu-sb-proxy". + + - cpu-handle + Usage: required + Definition: A phandle to associate this debug node with its cpu. + + - reg + Usage: required + Value type: <prop-encoded-array> + Definition: A standard property. Specifies the physical address + offset and length of the DCSR space registers of the device + configuration block. + +EXAMPLE + dcsr-cpu-sb-proxy@40000 { + compatible = "fsl,dcsr-e500mc-sb-proxy", + "fsl,dcsr-cpu-sb-proxy"; + cpu-handle = <&cpu0>; + reg = <0x40000 0x1000>; + }; + dcsr-cpu-sb-proxy@41000 { + compatible = "fsl,dcsr-e500mc-sb-proxy", + "fsl,dcsr-cpu-sb-proxy"; + cpu-handle = <&cpu1>; + reg = <0x41000 0x1000>; + }; + +======================================================================= diff --git a/Documentation/devicetree/bindings/powerpc/fsl/msi-pic.txt b/Documentation/devicetree/bindings/powerpc/fsl/msi-pic.txt index 70558c3f368..5d586e1ccaf 100644 --- a/Documentation/devicetree/bindings/powerpc/fsl/msi-pic.txt +++ b/Documentation/devicetree/bindings/powerpc/fsl/msi-pic.txt @@ -25,6 +25,16 @@ Required properties: are routed to IPIC, and for 85xx/86xx cpu the interrupts are routed to MPIC. +Optional properties: +- msi-address-64: 64-bit PCI address of the MSIIR register. The MSIIR register + is used for MSI messaging. The address of MSIIR in PCI address space is + the MSI message address. + + This property may be used in virtualized environments where the hypervisor + has created an alternate mapping for the MSIR block. See below for an + explanation. + + Example: msi@41600 { compatible = "fsl,mpc8610-msi", "fsl,mpic-msi"; @@ -41,3 +51,35 @@ Example: 0xe7 0>; interrupt-parent = <&mpic>; }; + +The Freescale hypervisor and msi-address-64 +------------------------------------------- +Normally, PCI devices have access to all of CCSR via an ATMU mapping. The +Freescale MSI driver calculates the address of MSIIR (in the MSI register +block) and sets that address as the MSI message address. + +In a virtualized environment, the hypervisor may need to create an IOMMU +mapping for MSIIR. The Freescale ePAPR hypervisor has this requirement +because of hardware limitations of the Peripheral Access Management Unit +(PAMU), which is currently the only IOMMU that the hypervisor supports. +The ATMU is programmed with the guest physical address, and the PAMU +intercepts transactions and reroutes them to the true physical address. + +In the PAMU, each PCI controller is given only one primary window. The +PAMU restricts DMA operations so that they can only occur within a window. +Because PCI devices must be able to DMA to memory, the primary window must +be used to cover all of the guest's memory space. + +PAMU primary windows can be divided into 256 subwindows, and each +subwindow can have its own address mapping ("guest physical" to "true +physical"). However, each subwindow has to have the same alignment, which +means they cannot be located at just any address. Because of these +restrictions, it is usually impossible to create a 4KB subwindow that +covers MSIIR where it's normally located. + +Therefore, the hypervisor has to create a subwindow inside the same +primary window used for memory, but mapped to the MSIR block (where MSIIR +lives). The first subwindow after the end of guest memory is used for +this. The address specified in the msi-address-64 property is the PCI +address of MSIIR. The hypervisor configures the PAMU to map that address to +the true physical address of MSIIR. diff --git a/Documentation/oops-tracing.txt b/Documentation/oops-tracing.txt index 6fe9001b926..13032c0140d 100644 --- a/Documentation/oops-tracing.txt +++ b/Documentation/oops-tracing.txt @@ -263,6 +263,8 @@ characters, each representing a particular tainted value. 12: 'I' if the kernel is working around a severe bug in the platform firmware (BIOS or similar). + 13: 'O' if an externally-built ("out-of-tree") module has been loaded. + The primary reason for the 'Tainted: ' string is to tell kernel debuggers if this is a clean kernel or if anything unusual has occurred. Tainting is permanent: even if an offending module is diff --git a/Documentation/power/freezing-of-tasks.txt b/Documentation/power/freezing-of-tasks.txt index 38b57248fd6..316c2ba187f 100644 --- a/Documentation/power/freezing-of-tasks.txt +++ b/Documentation/power/freezing-of-tasks.txt @@ -22,12 +22,12 @@ try_to_freeze_tasks() that sets TIF_FREEZE for all of the freezable tasks and either wakes them up, if they are kernel threads, or sends fake signals to them, if they are user space processes. A task that has TIF_FREEZE set, should react to it by calling the function called refrigerator() (defined in -kernel/power/process.c), which sets the task's PF_FROZEN flag, changes its state +kernel/freezer.c), which sets the task's PF_FROZEN flag, changes its state to TASK_UNINTERRUPTIBLE and makes it loop until PF_FROZEN is cleared for it. Then, we say that the task is 'frozen' and therefore the set of functions handling this mechanism is referred to as 'the freezer' (these functions are -defined in kernel/power/process.c and include/linux/freezer.h). User space -processes are generally frozen before kernel threads. +defined in kernel/power/process.c, kernel/freezer.c & include/linux/freezer.h). +User space processes are generally frozen before kernel threads. It is not recommended to call refrigerator() directly. Instead, it is recommended to use the try_to_freeze() function (defined in @@ -95,7 +95,7 @@ after the memory for the image has been freed, we don't want tasks to allocate additional memory and we prevent them from doing that by freezing them earlier. [Of course, this also means that device drivers should not allocate substantial amounts of memory from their .suspend() callbacks before hibernation, but this -is e separate issue.] +is a separate issue.] 3. The third reason is to prevent user space processes and some kernel threads from interfering with the suspending and resuming of devices. A user space diff --git a/Documentation/power/runtime_pm.txt b/Documentation/power/runtime_pm.txt index 0e856088db7..5336149f831 100644 --- a/Documentation/power/runtime_pm.txt +++ b/Documentation/power/runtime_pm.txt @@ -789,6 +789,16 @@ will behave normally, not taking the autosuspend delay into account. Similarly, if the power.use_autosuspend field isn't set then the autosuspend helper functions will behave just like the non-autosuspend counterparts. +Under some circumstances a driver or subsystem may want to prevent a device +from autosuspending immediately, even though the usage counter is zero and the +autosuspend delay time has expired. If the ->runtime_suspend() callback +returns -EAGAIN or -EBUSY, and if the next autosuspend delay expiration time is +in the future (as it normally would be if the callback invoked +pm_runtime_mark_last_busy()), the PM core will automatically reschedule the +autosuspend. The ->runtime_suspend() callback can't do this rescheduling +itself because no suspend requests of any kind are accepted while the device is +suspending (i.e., while the callback is running). + The implementation is well suited for asynchronous use in interrupt contexts. However such use inevitably involves races, because the PM core can't synchronize ->runtime_suspend() callbacks with the arrival of I/O requests. diff --git a/Documentation/watchdog/convert_drivers_to_kernel_api.txt b/Documentation/watchdog/convert_drivers_to_kernel_api.txt new file mode 100644 index 00000000000..ae1e90036d0 --- /dev/null +++ b/Documentation/watchdog/convert_drivers_to_kernel_api.txt @@ -0,0 +1,195 @@ +Converting old watchdog drivers to the watchdog framework +by Wolfram Sang <w.sang@pengutronix.de> +========================================================= + +Before the watchdog framework came into the kernel, every driver had to +implement the API on its own. Now, as the framework factored out the common +components, those drivers can be lightened making it a user of the framework. +This document shall guide you for this task. The necessary steps are described +as well as things to look out for. + + +Remove the file_operations struct +--------------------------------- + +Old drivers define their own file_operations for actions like open(), write(), +etc... These are now handled by the framework and just call the driver when +needed. So, in general, the 'file_operations' struct and assorted functions can +go. Only very few driver-specific details have to be moved to other functions. +Here is a overview of the functions and probably needed actions: + +- open: Everything dealing with resource management (file-open checks, magic + close preparations) can simply go. Device specific stuff needs to go to the + driver specific start-function. Note that for some drivers, the start-function + also serves as the ping-function. If that is the case and you need start/stop + to be balanced (clocks!), you are better off refactoring a separate start-function. + +- close: Same hints as for open apply. + +- write: Can simply go, all defined behaviour is taken care of by the framework, + i.e. ping on write and magic char ('V') handling. + +- ioctl: While the driver is allowed to have extensions to the IOCTL interface, + the most common ones are handled by the framework, supported by some assistance + from the driver: + + WDIOC_GETSUPPORT: + Returns the mandatory watchdog_info struct from the driver + + WDIOC_GETSTATUS: + Needs the status-callback defined, otherwise returns 0 + + WDIOC_GETBOOTSTATUS: + Needs the bootstatus member properly set. Make sure it is 0 if you + don't have further support! + + WDIOC_SETOPTIONS: + No preparations needed + + WDIOC_KEEPALIVE: + If wanted, options in watchdog_info need to have WDIOF_KEEPALIVEPING + set + + WDIOC_SETTIMEOUT: + Options in watchdog_info need to have WDIOF_SETTIMEOUT set + and a set_timeout-callback has to be defined. The core will also + do limit-checking, if min_timeout and max_timeout in the watchdog + device are set. All is optional. + + WDIOC_GETTIMEOUT: + No preparations needed + + Other IOCTLs can be served using the ioctl-callback. Note that this is mainly + intended for porting old drivers; new drivers should not invent private IOCTLs. + Private IOCTLs are processed first. When the callback returns with + -ENOIOCTLCMD, the IOCTLs of the framework will be tried, too. Any other error + is directly given to the user. + +Example conversion: + +-static const struct file_operations s3c2410wdt_fops = { +- .owner = THIS_MODULE, +- .llseek = no_llseek, +- .write = s3c2410wdt_write, +- .unlocked_ioctl = s3c2410wdt_ioctl, +- .open = s3c2410wdt_open, +- .release = s3c2410wdt_release, +-}; + +Check the functions for device-specific stuff and keep it for later +refactoring. The rest can go. + + +Remove the miscdevice +--------------------- + +Since the file_operations are gone now, you can also remove the 'struct +miscdevice'. The framework will create it on watchdog_dev_register() called by +watchdog_register_device(). + +-static struct miscdevice s3c2410wdt_miscdev = { +- .minor = WATCHDOG_MINOR, +- .name = "watchdog", +- .fops = &s3c2410wdt_fops, +-}; + + +Remove obsolete includes and defines +------------------------------------ + +Because of the simplifications, a few defines are probably unused now. Remove +them. Includes can be removed, too. For example: + +- #include <linux/fs.h> +- #include <linux/miscdevice.h> (if MODULE_ALIAS_MISCDEV is not used) +- #include <linux/uaccess.h> (if no custom IOCTLs are used) + + +Add the watchdog operations +--------------------------- + +All possible callbacks are defined in 'struct watchdog_ops'. You can find it +explained in 'watchdog-kernel-api.txt' in this directory. start(), stop() and +owner must be set, the rest are optional. You will easily find corresponding +functions in the old driver. Note that you will now get a pointer to the +watchdog_device as a parameter to these functions, so you probably have to +change the function header. Other changes are most likely not needed, because +here simply happens the direct hardware access. If you have device-specific +code left from the above steps, it should be refactored into these callbacks. + +Here is a simple example: + ++static struct watchdog_ops s3c2410wdt_ops = { ++ .owner = THIS_MODULE, ++ .start = s3c2410wdt_start, ++ .stop = s3c2410wdt_stop, ++ .ping = s3c2410wdt_keepalive, ++ .set_timeout = s3c2410wdt_set_heartbeat, ++}; + +A typical function-header change looks like: + +-static void s3c2410wdt_keepalive(void) ++static int s3c2410wdt_keepalive(struct watchdog_device *wdd) + { +... ++ ++ return 0; + } + +... + +- s3c2410wdt_keepalive(); ++ s3c2410wdt_keepalive(&s3c2410_wdd); + + +Add the watchdog device +----------------------- + +Now we need to create a 'struct watchdog_device' and populate it with the +necessary information for the framework. The struct is also explained in detail +in 'watchdog-kernel-api.txt' in this directory. We pass it the mandatory +watchdog_info struct and the newly created watchdog_ops. Often, old drivers +have their own record-keeping for things like bootstatus and timeout using +static variables. Those have to be converted to use the members in +watchdog_device. Note that the timeout values are unsigned int. Some drivers +use signed int, so this has to be converted, too. + +Here is a simple example for a watchdog device: + ++static struct watchdog_device s3c2410_wdd = { ++ .info = &s3c2410_wdt_ident, ++ .ops = &s3c2410wdt_ops, ++}; + + +Register the watchdog device +---------------------------- + +Replace misc_register(&miscdev) with watchdog_register_device(&watchdog_dev). +Make sure the return value gets checked and the error message, if present, +still fits. Also convert the unregister case. + +- ret = misc_register(&s3c2410wdt_miscdev); ++ ret = watchdog_register_device(&s3c2410_wdd); + +... + +- misc_deregister(&s3c2410wdt_miscdev); ++ watchdog_unregister_device(&s3c2410_wdd); + + +Update the Kconfig-entry +------------------------ + +The entry for the driver now needs to select WATCHDOG_CORE: + ++ select WATCHDOG_CORE + + +Create a patch and send it to upstream +-------------------------------------- + +Make sure you understood Documentation/SubmittingPatches and send your patch to +linux-watchdog@vger.kernel.org. We are looking forward to it :) + |