diff options
Diffstat (limited to 'Documentation/arm')
| -rw-r--r-- | Documentation/arm/00-INDEX | 16 | ||||
| -rw-r--r-- | Documentation/arm/Booting | 42 | ||||
| -rw-r--r-- | Documentation/arm/Marvell/README | 42 | ||||
| -rw-r--r-- | Documentation/arm/OMAP/omap_pm | 2 | ||||
| -rw-r--r-- | Documentation/arm/Samsung-S3C24XX/GPIO.txt | 13 | ||||
| -rw-r--r-- | Documentation/arm/kernel_mode_neon.txt | 121 | ||||
| -rw-r--r-- | Documentation/arm/memory.txt | 9 | ||||
| -rw-r--r-- | Documentation/arm/sti/stih407-overview.txt | 18 | ||||
| -rw-r--r-- | Documentation/arm/sunxi/README | 26 | ||||
| -rw-r--r-- | Documentation/arm/uefi.txt | 64 |
10 files changed, 320 insertions, 33 deletions
diff --git a/Documentation/arm/00-INDEX b/Documentation/arm/00-INDEX index 36420e116c9..3b08bc2b04c 100644 --- a/Documentation/arm/00-INDEX +++ b/Documentation/arm/00-INDEX @@ -4,6 +4,8 @@ Booting - requirements for booting Interrupts - ARM Interrupt subsystem documentation +IXP4xx + - Intel IXP4xx Network processor. msm - MSM specific documentation Netwinder @@ -24,8 +26,16 @@ SPEAr - ST SPEAr platform Linux Overview VFP/ - Release notes for Linux Kernel Vector Floating Point support code +cluster-pm-race-avoidance.txt + - Algorithm for CPU and Cluster setup/teardown empeg/ - Ltd's Empeg MP3 Car Audio Player +firmware.txt + - Secure firmware registration and calling. +kernel_mode_neon.txt + - How to use NEON instructions in kernel mode +kernel_user_helpers.txt + - Helper functions in kernel space made available for userspace. mem_alignment - alignment abort handler documentation memory.txt @@ -34,3 +44,9 @@ nwfpe/ - NWFPE floating point emulator documentation swp_emulation - SWP/SWPB emulation handler/logging description +tcm.txt + - ARM Tightly Coupled Memory +uefi.txt + - [U]EFI configuration and runtime services documentation +vlocks.txt + - Voting locks, low-level mechanism relying on memory system atomic writes. diff --git a/Documentation/arm/Booting b/Documentation/arm/Booting index 0c1f475fdf3..371814a3671 100644 --- a/Documentation/arm/Booting +++ b/Documentation/arm/Booting @@ -18,7 +18,8 @@ following: 2. Initialise one serial port. 3. Detect the machine type. 4. Setup the kernel tagged list. -5. Call the kernel image. +5. Load initramfs. +6. Call the kernel image. 1. Setup and initialise RAM @@ -120,12 +121,27 @@ tagged list. The boot loader must pass at a minimum the size and location of the system memory, and the root filesystem location. The dtb must be placed in a region of memory where the kernel decompressor will not -overwrite it. The recommended placement is in the first 16KiB of RAM -with the caveat that it may not be located at physical address 0 since -the kernel interprets a value of 0 in r2 to mean neither a tagged list -nor a dtb were passed. +overwrite it, whilst remaining within the region which will be covered +by the kernel's low-memory mapping. -5. Calling the kernel image +A safe location is just above the 128MiB boundary from start of RAM. + +5. Load initramfs. +------------------ + +Existing boot loaders: OPTIONAL +New boot loaders: OPTIONAL + +If an initramfs is in use then, as with the dtb, it must be placed in +a region of memory where the kernel decompressor will not overwrite it +while also with the region which will be covered by the kernel's +low-memory mapping. + +A safe location is just above the device tree blob which itself will +be loaded just above the 128MiB boundary from the start of RAM as +recommended above. + +6. Calling the kernel image --------------------------- Existing boot loaders: MANDATORY @@ -136,11 +152,17 @@ is stored in flash, and is linked correctly to be run from flash, then it is legal for the boot loader to call the zImage in flash directly. -The zImage may also be placed in system RAM (at any location) and -called there. Note that the kernel uses 16K of RAM below the image -to store page tables. The recommended placement is 32KiB into RAM. +The zImage may also be placed in system RAM and called there. The +kernel should be placed in the first 128MiB of RAM. It is recommended +that it is loaded above 32MiB in order to avoid the need to relocate +prior to decompression, which will make the boot process slightly +faster. + +When booting a raw (non-zImage) kernel the constraints are tighter. +In this case the kernel must be loaded at an offset into system equal +to TEXT_OFFSET - PAGE_OFFSET. -In either case, the following conditions must be met: +In any case, the following conditions must be met: - Quiesce all DMA capable devices so that memory does not get corrupted by bogus network packets or disk data. This will save diff --git a/Documentation/arm/Marvell/README b/Documentation/arm/Marvell/README index 8f08a86e03b..2cce5401e32 100644 --- a/Documentation/arm/Marvell/README +++ b/Documentation/arm/Marvell/README @@ -83,13 +83,24 @@ EBU Armada family 88F6710 88F6707 88F6W11 + Product Brief: http://www.marvell.com/embedded-processors/armada-300/assets/Marvell_ARMADA_370_SoC.pdf + + Armada 375 Flavors: + 88F6720 + Product Brief: http://www.marvell.com/embedded-processors/armada-300/assets/ARMADA_375_SoC-01_product_brief.pdf + + Armada 380/385 Flavors: + 88F6810 + 88F6820 + 88F6828 Armada XP Flavors: MV78230 MV78260 MV78460 + NOTE: not to be confused with the non-SMP 78xx0 SoCs + Product Brief: http://www.marvell.com/embedded-processors/armada-xp/assets/Marvell-ArmadaXP-SoC-product%20brief.pdf - Product Brief: http://www.marvell.com/embedded-processors/armada-xp/assets/Marvell-ArmadaXP-SoC-product%20brief.pdf No public datasheet available. Core: Sheeva ARMv7 compatible @@ -210,6 +221,35 @@ MMP/MMP2 family (communication processor) Linux kernel mach directory: arch/arm/mach-mmp Linux kernel plat directory: arch/arm/plat-pxa +Berlin family (Digital Entertainment) +------------------------------------- + + Flavors: + 88DE3005, Armada 1500-mini + Design name: BG2CD + Core: ARM Cortex-A9, PL310 L2CC + Homepage: http://www.marvell.com/digital-entertainment/armada-1500-mini/ + 88DE3100, Armada 1500 + Design name: BG2 + Core: Marvell PJ4B (ARMv7), Tauros3 L2CC + Homepage: http://www.marvell.com/digital-entertainment/armada-1500/ + Product Brief: http://www.marvell.com/digital-entertainment/armada-1500/assets/Marvell-ARMADA-1500-Product-Brief.pdf + 88DE3114, Armada 1500 Pro + Design name: BG2-Q + Core: Quad Core ARM Cortex-A9, PL310 L2CC + Homepage: http://www.marvell.com/digital-entertainment/armada-1500-pro/ + Product Brief: http://www.marvell.com/digital-entertainment/armada-1500-pro/assets/Marvell_ARMADA_1500_PRO-01_product_brief.pdf + 88DE???? + Design name: BG3 + Core: ARM Cortex-A15, CA15 integrated L2CC + + Homepage: http://www.marvell.com/digital-entertainment/ + Directory: arch/arm/mach-berlin + + Comments: + * This line of SoCs is based on Marvell Sheeva or ARM Cortex CPUs + with Synopsys DesignWare (IRQ, GPIO, Timers, ...) and PXA IP (SDHCI, USB, ETH, ...). + Long-term plans --------------- diff --git a/Documentation/arm/OMAP/omap_pm b/Documentation/arm/OMAP/omap_pm index 9012bb03909..4ae915a9f89 100644 --- a/Documentation/arm/OMAP/omap_pm +++ b/Documentation/arm/OMAP/omap_pm @@ -78,7 +78,7 @@ to NULL. Drivers should use the following idiom: The most common usage of these functions will probably be to specify the maximum time from when an interrupt occurs, to when the device becomes accessible. To accomplish this, driver writers should use the -set_max_mpu_wakeup_lat() function to to constrain the MPU wakeup +set_max_mpu_wakeup_lat() function to constrain the MPU wakeup latency, and the set_max_dev_wakeup_lat() function to constrain the device wakeup latency (from clk_enable() to accessibility). For example, diff --git a/Documentation/arm/Samsung-S3C24XX/GPIO.txt b/Documentation/arm/Samsung-S3C24XX/GPIO.txt index 8b46c79679c..0ebd7e2244d 100644 --- a/Documentation/arm/Samsung-S3C24XX/GPIO.txt +++ b/Documentation/arm/Samsung-S3C24XX/GPIO.txt @@ -85,21 +85,10 @@ between the calls. Headers ------- - See arch/arm/mach-s3c2410/include/mach/regs-gpio.h for the list + See arch/arm/mach-s3c24xx/include/mach/regs-gpio.h for the list of GPIO pins, and the configuration values for them. This is included by using #include <mach/regs-gpio.h> - The GPIO management functions are defined in the hardware - header arch/arm/mach-s3c2410/include/mach/hardware.h which can be - included by #include <mach/hardware.h> - - A useful amount of documentation can be found in the hardware - header on how the GPIO functions (and others) work. - - Whilst a number of these functions do make some checks on what - is passed to them, for speed of use, they may not always ensure - that the user supplied data to them is correct. - PIN Numbers ----------- diff --git a/Documentation/arm/kernel_mode_neon.txt b/Documentation/arm/kernel_mode_neon.txt new file mode 100644 index 00000000000..525452726d3 --- /dev/null +++ b/Documentation/arm/kernel_mode_neon.txt @@ -0,0 +1,121 @@ +Kernel mode NEON +================ + +TL;DR summary +------------- +* Use only NEON instructions, or VFP instructions that don't rely on support + code +* Isolate your NEON code in a separate compilation unit, and compile it with + '-mfpu=neon -mfloat-abi=softfp' +* Put kernel_neon_begin() and kernel_neon_end() calls around the calls into your + NEON code +* Don't sleep in your NEON code, and be aware that it will be executed with + preemption disabled + + +Introduction +------------ +It is possible to use NEON instructions (and in some cases, VFP instructions) in +code that runs in kernel mode. However, for performance reasons, the NEON/VFP +register file is not preserved and restored at every context switch or taken +exception like the normal register file is, so some manual intervention is +required. Furthermore, special care is required for code that may sleep [i.e., +may call schedule()], as NEON or VFP instructions will be executed in a +non-preemptible section for reasons outlined below. + + +Lazy preserve and restore +------------------------- +The NEON/VFP register file is managed using lazy preserve (on UP systems) and +lazy restore (on both SMP and UP systems). This means that the register file is +kept 'live', and is only preserved and restored when multiple tasks are +contending for the NEON/VFP unit (or, in the SMP case, when a task migrates to +another core). Lazy restore is implemented by disabling the NEON/VFP unit after +every context switch, resulting in a trap when subsequently a NEON/VFP +instruction is issued, allowing the kernel to step in and perform the restore if +necessary. + +Any use of the NEON/VFP unit in kernel mode should not interfere with this, so +it is required to do an 'eager' preserve of the NEON/VFP register file, and +enable the NEON/VFP unit explicitly so no exceptions are generated on first +subsequent use. This is handled by the function kernel_neon_begin(), which +should be called before any kernel mode NEON or VFP instructions are issued. +Likewise, the NEON/VFP unit should be disabled again after use to make sure user +mode will hit the lazy restore trap upon next use. This is handled by the +function kernel_neon_end(). + + +Interruptions in kernel mode +---------------------------- +For reasons of performance and simplicity, it was decided that there shall be no +preserve/restore mechanism for the kernel mode NEON/VFP register contents. This +implies that interruptions of a kernel mode NEON section can only be allowed if +they are guaranteed not to touch the NEON/VFP registers. For this reason, the +following rules and restrictions apply in the kernel: +* NEON/VFP code is not allowed in interrupt context; +* NEON/VFP code is not allowed to sleep; +* NEON/VFP code is executed with preemption disabled. + +If latency is a concern, it is possible to put back to back calls to +kernel_neon_end() and kernel_neon_begin() in places in your code where none of +the NEON registers are live. (Additional calls to kernel_neon_begin() should be +reasonably cheap if no context switch occurred in the meantime) + + +VFP and support code +-------------------- +Earlier versions of VFP (prior to version 3) rely on software support for things +like IEEE-754 compliant underflow handling etc. When the VFP unit needs such +software assistance, it signals the kernel by raising an undefined instruction +exception. The kernel responds by inspecting the VFP control registers and the +current instruction and arguments, and emulates the instruction in software. + +Such software assistance is currently not implemented for VFP instructions +executed in kernel mode. If such a condition is encountered, the kernel will +fail and generate an OOPS. + + +Separating NEON code from ordinary code +--------------------------------------- +The compiler is not aware of the special significance of kernel_neon_begin() and +kernel_neon_end(), i.e., that it is only allowed to issue NEON/VFP instructions +between calls to these respective functions. Furthermore, GCC may generate NEON +instructions of its own at -O3 level if -mfpu=neon is selected, and even if the +kernel is currently compiled at -O2, future changes may result in NEON/VFP +instructions appearing in unexpected places if no special care is taken. + +Therefore, the recommended and only supported way of using NEON/VFP in the +kernel is by adhering to the following rules: +* isolate the NEON code in a separate compilation unit and compile it with + '-mfpu=neon -mfloat-abi=softfp'; +* issue the calls to kernel_neon_begin(), kernel_neon_end() as well as the calls + into the unit containing the NEON code from a compilation unit which is *not* + built with the GCC flag '-mfpu=neon' set. + +As the kernel is compiled with '-msoft-float', the above will guarantee that +both NEON and VFP instructions will only ever appear in designated compilation +units at any optimization level. + + +NEON assembler +-------------- +NEON assembler is supported with no additional caveats as long as the rules +above are followed. + + +NEON code generated by GCC +-------------------------- +The GCC option -ftree-vectorize (implied by -O3) tries to exploit implicit +parallelism, and generates NEON code from ordinary C source code. This is fully +supported as long as the rules above are followed. + + +NEON intrinsics +--------------- +NEON intrinsics are also supported. However, as code using NEON intrinsics +relies on the GCC header <arm_neon.h>, (which #includes <stdint.h>), you should +observe the following in addition to the rules above: +* Compile the unit containing the NEON intrinsics with '-ffreestanding' so GCC + uses its builtin version of <stdint.h> (this is a C99 header which the kernel + does not supply); +* Include <arm_neon.h> last, or at least after <linux/types.h> diff --git a/Documentation/arm/memory.txt b/Documentation/arm/memory.txt index 4bfb9ffbdbc..38dc06d0a79 100644 --- a/Documentation/arm/memory.txt +++ b/Documentation/arm/memory.txt @@ -41,16 +41,9 @@ fffe8000 fffeffff DTCM mapping area for platforms with fffe0000 fffe7fff ITCM mapping area for platforms with ITCM mounted inside the CPU. -fff00000 fffdffff Fixmap mapping region. Addresses provided +ffc00000 ffdfffff Fixmap mapping region. Addresses provided by fix_to_virt() will be located here. -ffc00000 ffefffff DMA memory mapping region. Memory returned - by the dma_alloc_xxx functions will be - dynamically mapped here. - -ff000000 ffbfffff Reserved for future expansion of DMA - mapping region. - fee00000 feffffff Mapping of PCI I/O space. This is a static mapping within the vmalloc space. diff --git a/Documentation/arm/sti/stih407-overview.txt b/Documentation/arm/sti/stih407-overview.txt new file mode 100644 index 00000000000..3343f32f58b --- /dev/null +++ b/Documentation/arm/sti/stih407-overview.txt @@ -0,0 +1,18 @@ + STiH407 Overview + ================ + +Introduction +------------ + + The STiH407 is the new generation of SoC for Multi-HD, AVC set-top boxes + and server/connected client application for satellite, cable, terrestrial + and IP-STB markets. + + Features + - ARM Cortex-A9 1.5 GHz dual core CPU (28nm) + - SATA2, USB 3.0, PCIe, Gbit Ethernet + + Document Author + --------------- + + Maxime Coquelin <maxime.coquelin@st.com>, (c) 2014 ST Microelectronics diff --git a/Documentation/arm/sunxi/README b/Documentation/arm/sunxi/README index e3f93fb9224..7945238453e 100644 --- a/Documentation/arm/sunxi/README +++ b/Documentation/arm/sunxi/README @@ -10,6 +10,10 @@ SunXi family Linux kernel mach directory: arch/arm/mach-sunxi Flavors: + * ARM926 based SoCs + - Allwinner F20 (sun3i) + + Not Supported + * ARM Cortex-A8 based SoCs - Allwinner A10 (sun4i) + Datasheet @@ -25,4 +29,24 @@ SunXi family + Datasheet http://dl.linux-sunxi.org/A13/A13%20Datasheet%20-%20v1.12%20%282012-03-29%29.pdf + User Manual - http://dl.linux-sunxi.org/A13/A13%20User%20Manual%20-%20v1.2%20%282013-08-08%29.pdf + http://dl.linux-sunxi.org/A13/A13%20User%20Manual%20-%20v1.2%20%282013-01-08%29.pdf + + * Dual ARM Cortex-A7 based SoCs + - Allwinner A20 (sun7i) + + User Manual + http://dl.linux-sunxi.org/A20/A20%20User%20Manual%202013-03-22.pdf + + - Allwinner A23 + + Not Supported + + * Quad ARM Cortex-A7 based SoCs + - Allwinner A31 (sun6i) + + Datasheet + http://dl.linux-sunxi.org/A31/A31%20Datasheet%20-%20v1.00%20(2012-12-24).pdf + + - Allwinner A31s (sun6i) + + Not Supported + + * Quad ARM Cortex-A15, Quad ARM Cortex-A7 based SoCs + - Allwinner A80 + + Not Supported
\ No newline at end of file diff --git a/Documentation/arm/uefi.txt b/Documentation/arm/uefi.txt new file mode 100644 index 00000000000..d60030a1b90 --- /dev/null +++ b/Documentation/arm/uefi.txt @@ -0,0 +1,64 @@ +UEFI, the Unified Extensible Firmware Interface, is a specification +governing the behaviours of compatible firmware interfaces. It is +maintained by the UEFI Forum - http://www.uefi.org/. + +UEFI is an evolution of its predecessor 'EFI', so the terms EFI and +UEFI are used somewhat interchangeably in this document and associated +source code. As a rule, anything new uses 'UEFI', whereas 'EFI' refers +to legacy code or specifications. + +UEFI support in Linux +===================== +Booting on a platform with firmware compliant with the UEFI specification +makes it possible for the kernel to support additional features: +- UEFI Runtime Services +- Retrieving various configuration information through the standardised + interface of UEFI configuration tables. (ACPI, SMBIOS, ...) + +For actually enabling [U]EFI support, enable: +- CONFIG_EFI=y +- CONFIG_EFI_VARS=y or m + +The implementation depends on receiving information about the UEFI environment +in a Flattened Device Tree (FDT) - so is only available with CONFIG_OF. + +UEFI stub +========= +The "stub" is a feature that extends the Image/zImage into a valid UEFI +PE/COFF executable, including a loader application that makes it possible to +load the kernel directly from the UEFI shell, boot menu, or one of the +lightweight bootloaders like Gummiboot or rEFInd. + +The kernel image built with stub support remains a valid kernel image for +booting in non-UEFI environments. + +UEFI kernel support on ARM +========================== +UEFI kernel support on the ARM architectures (arm and arm64) is only available +when boot is performed through the stub. + +When booting in UEFI mode, the stub deletes any memory nodes from a provided DT. +Instead, the kernel reads the UEFI memory map. + +The stub populates the FDT /chosen node with (and the kernel scans for) the +following parameters: +________________________________________________________________________________ +Name | Size | Description +================================================================================ +linux,uefi-system-table | 64-bit | Physical address of the UEFI System Table. +-------------------------------------------------------------------------------- +linux,uefi-mmap-start | 64-bit | Physical address of the UEFI memory map, + | | populated by the UEFI GetMemoryMap() call. +-------------------------------------------------------------------------------- +linux,uefi-mmap-size | 32-bit | Size in bytes of the UEFI memory map + | | pointed to in previous entry. +-------------------------------------------------------------------------------- +linux,uefi-mmap-desc-size | 32-bit | Size in bytes of each entry in the UEFI + | | memory map. +-------------------------------------------------------------------------------- +linux,uefi-mmap-desc-ver | 32-bit | Version of the mmap descriptor format. +-------------------------------------------------------------------------------- +linux,uefi-stub-kern-ver | string | Copy of linux_banner from build. +-------------------------------------------------------------------------------- + +For verbose debug messages, specify 'uefi_debug' on the kernel command line. |