Commit 4d2e26a3 authored by Mauro Carvalho Chehab's avatar Mauro Carvalho Chehab
Browse files

docs: powerpc: convert docs to ReST and rename to *.rst



Convert docs to ReST and add them to the arch-specific
book.

The conversion here was trivial, as almost every file there
was already using an elegant format close to ReST standard.

The changes were mostly to mark literal blocks and add a few
missing section title identifiers.

One note with regards to "--": on Sphinx, this can't be used
to identify a list, as it will format it badly. This can be
used, however, to identify a long hyphen - and "---" is an
even longer one.

At its new index.rst, let's add a :orphan: while this is not linked to
the main index.rst file, in order to avoid build warnings.

Signed-off-by: default avatarMauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com> # cxl
parent 0a8ad0ff
......@@ -403,7 +403,7 @@ That is, the recovery API only requires that:
.. note::
Implementation details for the powerpc platform are discussed in
the file Documentation/powerpc/eeh-pci-error-recovery.txt
the file Documentation/powerpc/eeh-pci-error-recovery.rst
As of this writing, there is a growing list of device drivers with
patches implementing error recovery. Not all of these patches are in
......@@ -422,3 +422,6 @@ That is, the recovery API only requires that:
- drivers/net/cxgb3
- drivers/net/s2io.c
- drivers/net/qlge
The End
-------
......@@ -143,6 +143,7 @@ implementation.
arm64/index
ia64/index
m68k/index
powerpc/index
riscv/index
s390/index
sh/index
......
========================
The PowerPC boot wrapper
------------------------
========================
Copyright (C) Secret Lab Technologies Ltd.
PowerPC image targets compresses and wraps the kernel image (vmlinux) with
......@@ -21,6 +23,7 @@ it uses the wrapper script (arch/powerpc/boot/wrapper) to generate target
image. The details of the build system is discussed in the next section.
Currently, the following image format targets exist:
==================== ========================================================
cuImage.%: Backwards compatible uImage for older version of
U-Boot (for versions that don't understand the device
tree). This image embeds a device tree blob inside
......@@ -29,31 +32,36 @@ Currently, the following image format targets exist:
with boot wrapper code that extracts data from the old
bd_info structure and loads the data into the device
tree before jumping into the kernel.
Because of the series of #ifdefs found in the
Because of the series of #ifdefs found in the
bd_info structure used in the old U-Boot interfaces,
cuImages are platform specific. Each specific
U-Boot platform has a different platform init file
which populates the embedded device tree with data
from the platform specific bd_info file. The platform
specific cuImage platform init code can be found in
arch/powerpc/boot/cuboot.*.c. Selection of the correct
`arch/powerpc/boot/cuboot.*.c`. Selection of the correct
cuImage init code for a specific board can be found in
the wrapper structure.
dtbImage.%: Similar to zImage, except device tree blob is embedded
inside the image instead of provided by firmware. The
output image file can be either an elf file or a flat
binary depending on the platform.
dtbImages are used on systems which do not have an
dtbImages are used on systems which do not have an
interface for passing a device tree directly.
dtbImages are similar to simpleImages except that
dtbImages have platform specific code for extracting
data from the board firmware, but simpleImages do not
talk to the firmware at all.
PlayStation 3 support uses dtbImage. So do Embedded
PlayStation 3 support uses dtbImage. So do Embedded
Planet boards using the PlanetCore firmware. Board
specific initialization code is typically found in a
file named arch/powerpc/boot/<platform>.c; but this
can be overridden by the wrapper script.
simpleImage.%: Firmware independent compressed image that does not
depend on any particular firmware interface and embeds
a device tree blob. This image is a flat binary that
......@@ -61,14 +69,16 @@ Currently, the following image format targets exist:
Firmware cannot pass any configuration data to the
kernel with this image type and it depends entirely on
the embedded device tree for all information.
The simpleImage is useful for booting systems with
The simpleImage is useful for booting systems with
an unknown firmware interface or for booting from
a debugger when no firmware is present (such as on
the Xilinx Virtex platform). The only assumption that
simpleImage makes is that RAM is correctly initialized
and that the MMU is either off or has RAM mapped to
base address 0.
simpleImage also supports inserting special platform
simpleImage also supports inserting special platform
specific initialization code to the start of the bootup
sequence. The virtex405 platform uses this feature to
ensure that the cache is invalidated before caching
......@@ -81,9 +91,11 @@ Currently, the following image format targets exist:
named (virtex405-<board>.dts). Search the wrapper
script for 'virtex405' and see the file
arch/powerpc/boot/virtex405-head.S for details.
treeImage.%; Image format for used with OpenBIOS firmware found
on some ppc4xx hardware. This image embeds a device
tree blob inside the image.
uImage: Native image format used by U-Boot. The uImage target
does not add any boot code. It just wraps a compressed
vmlinux in the uImage data structure. This image
......@@ -91,12 +103,14 @@ Currently, the following image format targets exist:
a device tree to the kernel at boot. If using an older
version of U-Boot, then you need to use a cuImage
instead.
zImage.%: Image format which does not embed a device tree.
Used by OpenFirmware and other firmware interfaces
which are able to supply a device tree. This image
expects firmware to provide the device tree at boot.
Typically, if you have general purpose PowerPC
hardware then you want this image format.
==================== ========================================================
Image types which embed a device tree blob (simpleImage, dtbImage, treeImage,
and cuImage) all generate the device tree blob from a file in the
......
============
CPU Families
============
......@@ -8,8 +9,8 @@ and are supported by arch/powerpc.
Book3S (aka sPAPR)
------------------
- Hash MMU
- Mix of 32 & 64 bit
- Hash MMU
- Mix of 32 & 64 bit::
+--------------+ +----------------+
| Old POWER | --------------> | RS64 (threads) |
......@@ -108,8 +109,8 @@ Book3S (aka sPAPR)
IBM BookE
---------
- Software loaded TLB.
- All 32 bit
- Software loaded TLB.
- All 32 bit::
+--------------+
| 401 |
......@@ -155,8 +156,8 @@ IBM BookE
Motorola/Freescale 8xx
----------------------
- Software loaded with hardware assist.
- All 32 bit
- Software loaded with hardware assist.
- All 32 bit::
+-------------+
| MPC8xx Core |
......@@ -166,9 +167,9 @@ Motorola/Freescale 8xx
Freescale BookE
---------------
- Software loaded TLB.
- e6500 adds HW loaded indirect TLB entries.
- Mix of 32 & 64 bit
- Software loaded TLB.
- e6500 adds HW loaded indirect TLB entries.
- Mix of 32 & 64 bit::
+--------------+
| e200 |
......@@ -207,8 +208,8 @@ Freescale BookE
IBM A2 core
-----------
- Book3E, software loaded TLB + HW loaded indirect TLB entries.
- 64 bit
- Book3E, software loaded TLB + HW loaded indirect TLB entries.
- 64 bit::
+--------------+ +----------------+
| A2 core | --> | WSP |
......
============
CPU Features
============
Hollis Blanchard <hollis@austin.ibm.com>
5 Jun 2002
......@@ -32,7 +36,7 @@ anyways).
After detecting the processor type, the kernel patches out sections of code
that shouldn't be used by writing nop's over it. Using cpufeatures requires
just 2 macros (found in arch/powerpc/include/asm/cputable.h), as seen in head.S
transfer_to_handler:
transfer_to_handler::
#ifdef CONFIG_ALTIVEC
BEGIN_FTR_SECTION
......
====================================
Coherent Accelerator Interface (CXL)
====================================
......@@ -21,6 +22,8 @@ Introduction
Hardware overview
=================
::
POWER8/9 FPGA
+----------+ +---------+
| | | |
......@@ -59,14 +62,16 @@ Hardware overview
the fault. The context to which this fault is serviced is based on
who owns that acceleration function.
POWER8 <-----> PSL Version 8 is compliant to the CAIA Version 1.0.
POWER9 <-----> PSL Version 9 is compliant to the CAIA Version 2.0.
- POWER8 and PSL Version 8 are compliant to the CAIA Version 1.0.
- POWER9 and PSL Version 9 are compliant to the CAIA Version 2.0.
This PSL Version 9 provides new features such as:
* Interaction with the nest MMU on the P9 chip.
* Native DMA support.
* Supports sending ASB_Notify messages for host thread wakeup.
* Supports Atomic operations.
* ....
* etc.
Cards with a PSL9 won't work on a POWER8 system and cards with a
PSL8 won't work on a POWER9 system.
......@@ -147,7 +152,9 @@ User API
master devices.
A userspace library libcxl is available here:
https://github.com/ibm-capi/libcxl
This provides a C interface to this kernel API.
open
......@@ -165,7 +172,8 @@ open
When all available contexts are allocated the open call will fail
and return -ENOSPC.
Note: IRQs need to be allocated for each context, which may limit
Note:
IRQs need to be allocated for each context, which may limit
the number of contexts that can be created, and therefore
how many times the device can be opened. The POWER8 CAPP
supports 2040 IRQs and 3 are used by the kernel, so 2037 are
......@@ -186,7 +194,9 @@ ioctl
updated as userspace allocates and frees memory. This ioctl
returns once the AFU context is started.
Takes a pointer to a struct cxl_ioctl_start_work:
Takes a pointer to a struct cxl_ioctl_start_work
::
struct cxl_ioctl_start_work {
__u64 flags;
......@@ -269,7 +279,7 @@ read
The buffer passed to read() must be at least 4K bytes.
The result of the read will be a buffer of one or more events,
each event is of type struct cxl_event, of varying size.
each event is of type struct cxl_event, of varying size::
struct cxl_event {
struct cxl_event_header header;
......@@ -280,7 +290,9 @@ read
};
};
The struct cxl_event_header is defined as:
The struct cxl_event_header is defined as
::
struct cxl_event_header {
__u16 type;
......@@ -307,7 +319,9 @@ read
For future extensions and padding.
If the event type is CXL_EVENT_AFU_INTERRUPT then the event
structure is defined as:
structure is defined as
::
struct cxl_event_afu_interrupt {
__u16 flags;
......@@ -326,7 +340,9 @@ read
For future extensions and padding.
If the event type is CXL_EVENT_DATA_STORAGE then the event
structure is defined as:
structure is defined as
::
struct cxl_event_data_storage {
__u16 flags;
......@@ -356,7 +372,9 @@ read
For future extensions
If the event type is CXL_EVENT_AFU_ERROR then the event structure
is defined as:
is defined as
::
struct cxl_event_afu_error {
__u16 flags;
......@@ -393,15 +411,15 @@ open
ioctl
-----
CXL_IOCTL_DOWNLOAD_IMAGE:
CXL_IOCTL_VALIDATE_IMAGE:
CXL_IOCTL_DOWNLOAD_IMAGE / CXL_IOCTL_VALIDATE_IMAGE:
Starts and controls flashing a new FPGA image. Partial
reconfiguration is not supported (yet), so the image must contain
a copy of the PSL and AFU(s). Since an image can be quite large,
the caller may have to iterate, splitting the image in smaller
chunks.
Takes a pointer to a struct cxl_adapter_image:
Takes a pointer to a struct cxl_adapter_image::
struct cxl_adapter_image {
__u64 flags;
__u64 data;
......@@ -442,7 +460,7 @@ Udev rules
The following udev rules could be used to create a symlink to the
most logical chardev to use in any programming mode (afuX.Yd for
dedicated, afuX.Ys for afu directed), since the API is virtually
identical for each:
identical for each::
SUBSYSTEM=="cxl", ATTRS{mode}=="dedicated_process", SYMLINK="cxl/%b"
SUBSYSTEM=="cxl", ATTRS{mode}=="afu_directed", \
......
================================
Coherent Accelerator (CXL) Flash
================================
Introduction
============
......@@ -28,7 +32,7 @@ Introduction
responsible for the initialization of the adapter, setting up the
special path for user space access, and performing error recovery. It
communicates directly the Flash Accelerator Functional Unit (AFU)
as described in Documentation/powerpc/cxl.txt.
as described in Documentation/powerpc/cxl.rst.
The cxlflash driver supports two, mutually exclusive, modes of
operation at the device (LUN) level:
......@@ -58,7 +62,7 @@ Overview
The CXL Flash Adapter Driver establishes a master context with the
AFU. It uses memory mapped I/O (MMIO) for this control and setup. The
Adapter Problem Space Memory Map looks like this:
Adapter Problem Space Memory Map looks like this::
+-------------------------------+
| 512 * 64 KB User MMIO |
......@@ -375,7 +379,7 @@ CXL Flash Driver Host IOCTLs
Each host adapter instance that is supported by the cxlflash driver
has a special character device associated with it to enable a set of
host management function. These character devices are hosted in a
class dedicated for cxlflash and can be accessed via /dev/cxlflash/*.
class dedicated for cxlflash and can be accessed via `/dev/cxlflash/*`.
Applications can be written to perform various functions using the
host ioctl APIs below.
......
=====================
DAWR issues on POWER9
============================
=====================
On POWER9 the Data Address Watchpoint Register (DAWR) can cause a checkstop
if it points to cache inhibited (CI) memory. Currently Linux has no way to
disinguish CI memory when configuring the DAWR, so (for now) the DAWR is
disabled by this commit:
disabled by this commit::
commit 9654153158d3e0684a1bdb76dbababdb7111d5a0
Author: Michael Neuling <mikey@neuling.org>
......@@ -12,7 +13,7 @@ disabled by this commit:
powerpc: Disable DAWR in the base POWER9 CPU features
Technical Details:
============================
==================
DAWR has 6 different ways of being set.
1) ptrace
......@@ -37,7 +38,7 @@ DAWR on the migration.
For xmon, the 'bd' command will return an error on P9.
Consequences for users
============================
======================
For GDB watchpoints (ie 'watch' command) on POWER9 bare metal , GDB
will accept the command. Unfortunately since there is no hardware
......@@ -57,8 +58,8 @@ trapped in GDB. The watchpoint is remembered, so if the guest is
migrated back to the POWER8 host, it will start working again.
Force enabling the DAWR
=============================
Kernels (since ~v5.2) have an option to force enable the DAWR via:
=======================
Kernels (since ~v5.2) have an option to force enable the DAWR via::
echo Y > /sys/kernel/debug/powerpc/dawr_enable_dangerous
......@@ -86,5 +87,7 @@ dawr_enable_dangerous file will fail if the hypervisor doesn't support
writing the DAWR.
To double check the DAWR is working, run this kernel selftest:
tools/testing/selftests/powerpc/ptrace/ptrace-hwbreak.c
Any errors/failures/skips mean something is wrong.
DSCR (Data Stream Control Register)
================================================
===================================
DSCR (Data Stream Control Register)
===================================
DSCR register in powerpc allows user to have some control of prefetch of data
stream in the processor. Please refer to the ISA documents or related manual
......@@ -10,14 +11,17 @@ user interface.
(A) Data Structures:
(1) thread_struct:
(1) thread_struct::
dscr /* Thread DSCR value */
dscr_inherit /* Thread has changed default DSCR */
(2) PACA:
(2) PACA::
dscr_default /* per-CPU DSCR default value */
(3) sysfs.c:
(3) sysfs.c::
dscr_default /* System DSCR default value */
(B) Scheduler Changes:
......@@ -35,8 +39,8 @@ user interface.
(C) SYSFS Interface:
Global DSCR default: /sys/devices/system/cpu/dscr_default
CPU specific DSCR default: /sys/devices/system/cpu/cpuN/dscr
- Global DSCR default: /sys/devices/system/cpu/dscr_default
- CPU specific DSCR default: /sys/devices/system/cpu/cpuN/dscr
Changing the global DSCR default in the sysfs will change all the CPU
specific DSCR defaults immediately in their PACA structures. Again if
......
==========================
PCI Bus EEH Error Recovery
==========================
Linas Vepstas <linas@austin.ibm.com>
PCI Bus EEH Error Recovery
--------------------------
Linas Vepstas
<linas@austin.ibm.com>
12 January 2005
12 January 2005
Overview:
......@@ -143,17 +143,17 @@ seen in /proc/ppc64/eeh (subject to change). Normally, almost
all of these occur during boot, when the PCI bus is scanned, where
a large number of 0xff reads are part of the bus scan procedure.
If a frozen slot is detected, code in
arch/powerpc/platforms/pseries/eeh.c will print a stack trace to
syslog (/var/log/messages). This stack trace has proven to be very
useful to device-driver authors for finding out at what point the EEH
error was detected, as the error itself usually occurs slightly
If a frozen slot is detected, code in
arch/powerpc/platforms/pseries/eeh.c will print a stack trace to
syslog (/var/log/messages). This stack trace has proven to be very
useful to device-driver authors for finding out at what point the EEH
error was detected, as the error itself usually occurs slightly
beforehand.
Next, it uses the Linux kernel notifier chain/work queue mechanism to
allow any interested parties to find out about the failure. Device
drivers, or other parts of the kernel, can use
eeh_register_notifier(struct notifier_block *) to find out about EEH
`eeh_register_notifier(struct notifier_block *)` to find out about EEH
events. The event will include a pointer to the pci device, the
device node and some state info. Receivers of the event can "do as
they wish"; the default handler will be described further in this
......@@ -162,10 +162,13 @@ section.
To assist in the recovery of the device, eeh.c exports the
following functions:
rtas_set_slot_reset() -- assert the PCI #RST line for 1/8th of a second
rtas_configure_bridge() -- ask firmware to configure any PCI bridges
rtas_set_slot_reset()
assert the PCI #RST line for 1/8th of a second
rtas_configure_bridge()
ask firmware to configure any PCI bridges
located topologically under the pci slot.
eeh_save_bars() and eeh_restore_bars(): save and restore the PCI
eeh_save_bars() and eeh_restore_bars():
save and restore the PCI
config-space info for a device and any devices under it.
......@@ -191,7 +194,7 @@ events get delivered to user-space scripts.
Following is an example sequence of events that cause a device driver
close function to be called during the first phase of an EEH reset.
The following sequence is an example of the pcnet32 device driver.
The following sequence is an example of the pcnet32 device driver::
rpa_php_unconfig_pci_adapter (struct slot *) // in rpaphp_pci.c
{
......@@ -241,53 +244,54 @@ The following sequence is an example of the pcnet32 device driver.
}}}}}}
in drivers/pci/pci_driver.c,
struct device_driver->remove() is just pci_device_remove()
which calls struct pci_driver->remove() which is pcnet32_remove_one()
which calls unregister_netdev() (in net/core/dev.c)
which calls dev_close() (in net/core/dev.c)
which calls dev->stop() which is pcnet32_close()
which then does the appropriate shutdown.
in drivers/pci/pci_driver.c,
struct device_driver->remove() is just pci_device_remove()
which calls struct pci_driver->remove() which is pcnet32_remove_one()
which calls unregister_netdev() (in net/core/dev.c)
which calls dev_close() (in net/core/dev.c)
which calls dev->stop() which is pcnet32_close()
which then does the appropriate shutdown.
---
Following is the analogous stack trace for events sent to user-space
when the pci device is unconfigured.
when the pci device is unconfigured::
rpa_php_unconfig_pci_adapter() { // in rpaphp_pci.c
calls
pci_remove_bus_device (struct pci_dev *) { // in /drivers/pci/remove.c
rpa_php_unconfig_pci_adapter() { // in rpaphp_pci.c
calls
pci_destroy_dev (struct pci_dev *) {
pci_remove_bus_device (struct pci_dev *) { // in /drivers/pci/remove.c
calls
device_unregister (&dev->dev) { // in /drivers/base/core.c
pci_destroy_dev (struct pci_dev *) {
calls
device_del(struct device * dev) { // in /drivers/base/core.c
device_unregister (&dev->dev) { // in /drivers/base/core.c
calls
kobject_del() { //in /libs/kobject.c
device_del(struct device * dev) { // in /drivers/base/core.c
calls
kobject_uevent() { // in /libs/kobject.c
kobject_del() { //in /libs/kobject.c
calls
kset_uevent() { // in /lib/kobject.c
kobject_uevent() { // in /libs/kobject.c
calls
kset->uevent_ops->uevent() // which is really just
a call to
dev_uevent() { // in /drivers/base/core.c
kset_uevent() { // in /lib/kobject.c
calls
dev->bus->uevent() which is really just a call to
pci_uevent () { // in drivers/pci/hotplug.c
which prints device name, etc....
kset->uevent_ops->uevent() // which is really just
a call to
dev_uevent() { // in /drivers/base/core.c
calls
dev->bus->uevent() which is really just a call to
pci_uevent () { // in drivers/pci/hotplug.c
which prints device name, etc....
}
}
}
then kobject_uevent() sends a netlink uevent to userspace
--> userspace uevent
(during early boot, nobody listens to netlink events and
kobject_uevent() executes uevent_helper[], which runs the
event process /sbin/hotplug)
then kobject_uevent() sends a netlink uevent to userspace
--> userspace uevent
(during early boot, nobody listens to netlink events and
kobject_uevent() executes uevent_helper[], which runs the
event process /sbin/hotplug)
}
}
}
kobject_del() then calls sysfs_remove_dir(), which would
trigger any user-space daemon that was watching /sysfs,
and notice the delete event.
kobject_del() then calls sysfs_remove_dir(), which would
trigger any user-space daemon that was watching /sysfs,
and notice the delete event.
Pro's and Con's of the Current Design
......@@ -299,12 +303,12 @@ individual device drivers, so that the current design throws a wide net.
The biggest negative of the design is that it potentially disturbs
network daemons and file systems that didn't need to be disturbed.
-- A minor complaint is that resetting the network card causes
- A minor complaint is that resetting the network card causes
user-space back-to-back ifdown/ifup burps that potentially disturb
network daemons, that didn't need to even know that the pci
card was being rebooted.
-- A more serious concern is that the same reset, for SCSI devices,
- A more serious concern is that the same reset, for SCSI devices,
causes havoc to mounted file systems. Scripts cannot post-facto
unmount a file system without flushing pending buffers, but this
is impossible, because I/O has already been stopped. Thus,
......@@ -322,7 +326,7 @@ network daemons and file systems that didn't need to be disturbed.
from the block layer. It would be very natural to add an EEH
reset into this chain of events.
-- If a SCSI error occurs for the root device, all is lost unless
- If a SCSI error occurs for the root device, all is lost unless
the sysadmin had the foresight to run /bin, /sbin, /etc, /var
and so on, out of ramdisk/tmpfs.
......@@ -330,5 +334,3 @@ network daemons and file systems that didn't need to be disturbed.
Conclusions
-----------
There's forward progress ...