From: Martin Sperl <kernel@xxxxxxxxxxxxxxxx>
This patchset adds a driver for the mcp25xxfd CanFD controller.
Most of the features of the controller are supported by this driver
release.
The controller includes a few features that the current core Can(FD)
implementation does not support: * Transmit Bandwidth Sharing bits
- this waits for a configurable number of syncronization bits before
atempting to transmit the next frame - for the moment controllable
via a module parameter
* SID11 with CanFD frames
- at this moment not supported by driver
* 3 transmit attempts in addition to ONE_SHOT
* transmitter delay compensation configurations
* micro second exact transmission and reception timestamps
- used internally by driver
* variable number of tx-fifos
- exposed via module parameter at this moment
The driver driver has been split into several patches - first just
initial setup of each section and then driver optimization patches.
As requested the driver has now also been split out into smaller
files for individual components of the driver - in the hope that this
has not been producing regressions...
The driver is able to handle reception of 99.95% of all CAN frames
of a 100% saturated 1MHz Can2.0 Bus with Frames with standard IDs and
DLC=0 on a Raspberry Pi 3. Note that this statistics is without injection
into the network stack, which then drops about 60% of all frames.
At this time the SPI bus is utilized 75% (when counting CS asserted)
and 60% from a SPI-Clock perspective.
On the Rasberry pi 3 in such a situation we are using 100% of one
CPU for the interrupt thread (as the spi driver is using polling for
short transfers) and this has exposed a performance inefficiency in the
spi framework that shows as the the spi-worker thread also consuming
CPU cycles (30% of one CPU in this test case) unnecessarily.
The driver also allows to use the INT0/1 pins as GPIOs.
Lots of internal data/statistics is exposed via debugfs.
On the HW side some errata related to SRAM access have been found
during the development of the patchsets. Since then an errata for
the controller has been shared by microchip.
At this very moment there is no 100% mitigation for this (besides
a newer version of the silicon).
The only instance where this is probably not an issue is when using
a SPI bus driver that reliably deasserts CS in the "requested"
time-frame of a few Can clock cycles.
When the spi-bus-driver is using GPIO-CS (which is nowadays the preferred
implementation of spi-bus-drivers) then we have to rely on
interrupt and interrupt worker thread scheduling latencies to be fast
enough to fullfill the requirements of the mcp2517fd of SCK stop to
CS-deassert. To achive this a faster CPU is needed and preferably more
cores.
A lot of possible mitigations have been investigated (Fifo ordering in
SRAM, the use of CRC SPI commands,...), but none have been successful.
That is why we are only able to reach 99.95% rate, because
when this issue occurres then there is the need to reconfigure the
controller and that takes some time which can not get used to process
frames. Fortunately this only happens on highly congested systems, but it
is more likely to occur on low end systems.
So as an example almost everything related to can-transmission can get
found in mcp25xxfd_can_tx.c. mcp25xxfd_can_rx.c is responsible for
can-reception and mcp25xxfd_can_int.c for interrupt handling.
Unfortunately the limit of the linux-can mailing-list seems lower than
128k (and thus patch 4 of the series seems not to have been accepted).
Thus V7 is essentially splitting V6 patch 4 into basic Can functionality
with Can RX working in V7 patch 4 and TX-support in V7 patch 5.
Changelog:
V1 -> V2: new more generic name based on feedback from microchip
cleanup of code (checkpatch)
address all feedback on code
handle (HW) systemerrors in a much better/reliable way
cleanup of dt custom properties removing (most) gpio
related properties
implemented GPIOLIB support as per feedback
V2 -> V3: added vendor-prefix for gpio-opendrain to dt-binding
added gpio-controller to dt-binding
added feedback by Rob Herring
waited for other feedback regarding the code
V3 -> V4: resend
Patch-1 (dt) added: Reviewed-by: Rob Herring <robh@xxxxxxxxxx>
V4 -> V5: reorganisation of the patchset into smaller patches
review of the whole driver code for better modularization
V5 -> V6: Major refactoring as per feedback from Wilhelm Grandegger
Fixing bugs reported by several other parties
Split out of optimizations into separate patches
V6 -> V7: added include linux/irqreturn.h (feedback by Eric Scholz)
move can transmission into a separate patch to reduce
the size of the individual patches to make the linux-can
mailing-list happy...
Martin Sperl (10):
dt-binding: can: mcp25xxfd: document device tree bindings
can: mcp25xxfd: Add Microchip mcp25xxfd CAN FD driver basics
can: mcp25xxfd: add gpiolib support for GPIO0/1 (aka. INT0/INT1)
can: mcp25xxfd: Add Microchip mcp25xxfd CAN FD driver
can: mcp25xxfd: Add Can transmission support
can: mcp25xxfd: optimize TEF read avoiding unnecessary SPI transfers
can: mcp25xxfd: optimize TEF reads reading multiple TEFs in one go
can: mcp25xxfd: optimize SPI reads of FIFOs in can2.0 mode
can: mcp25xxfd: add prediction of CanFD frames sizes based on history
can: mcp25xxfd: optimize reception of big CanFD frame reception with
BRS
.../bindings/net/can/microchip,mcp25xxfd.txt | 32 +
drivers/net/can/spi/Kconfig | 2 +
drivers/net/can/spi/Makefile | 2 +
drivers/net/can/spi/mcp25xxfd/Kconfig | 5 +
drivers/net/can/spi/mcp25xxfd/Makefile | 18 +
drivers/net/can/spi/mcp25xxfd/mcp25xxfd_base.c | 281 ++++++++
drivers/net/can/spi/mcp25xxfd/mcp25xxfd_base.h | 14 +
drivers/net/can/spi/mcp25xxfd/mcp25xxfd_can.c | 684 ++++++++++++++++++
drivers/net/can/spi/mcp25xxfd/mcp25xxfd_can.h | 56 ++
.../net/can/spi/mcp25xxfd/mcp25xxfd_can_debugfs.c | 235 ++++++
.../net/can/spi/mcp25xxfd/mcp25xxfd_can_debugfs.h | 44 ++
drivers/net/can/spi/mcp25xxfd/mcp25xxfd_can_fifo.c | 347 +++++++++
drivers/net/can/spi/mcp25xxfd/mcp25xxfd_can_fifo.h | 16 +
drivers/net/can/spi/mcp25xxfd/mcp25xxfd_can_id.h | 69 ++
drivers/net/can/spi/mcp25xxfd/mcp25xxfd_can_int.c | 706 ++++++++++++++++++
drivers/net/can/spi/mcp25xxfd/mcp25xxfd_can_int.h | 17 +
drivers/net/can/spi/mcp25xxfd/mcp25xxfd_can_priv.h | 203 ++++++
drivers/net/can/spi/mcp25xxfd/mcp25xxfd_can_rx.c | 521 ++++++++++++++
drivers/net/can/spi/mcp25xxfd/mcp25xxfd_can_rx.h | 18 +
drivers/net/can/spi/mcp25xxfd/mcp25xxfd_can_tx.c | 794 +++++++++++++++++++++
drivers/net/can/spi/mcp25xxfd/mcp25xxfd_can_tx.h | 86 +++
drivers/net/can/spi/mcp25xxfd/mcp25xxfd_clock.c | 485 +++++++++++++
drivers/net/can/spi/mcp25xxfd/mcp25xxfd_clock.h | 28 +
drivers/net/can/spi/mcp25xxfd/mcp25xxfd_cmd.c | 312 ++++++++
drivers/net/can/spi/mcp25xxfd/mcp25xxfd_cmd.h | 84 +++
drivers/net/can/spi/mcp25xxfd/mcp25xxfd_crc.c | 31 +
drivers/net/can/spi/mcp25xxfd/mcp25xxfd_crc.h | 15 +
drivers/net/can/spi/mcp25xxfd/mcp25xxfd_debugfs.c | 110 +++
drivers/net/can/spi/mcp25xxfd/mcp25xxfd_debugfs.h | 30 +
drivers/net/can/spi/mcp25xxfd/mcp25xxfd_ecc.c | 75 ++
drivers/net/can/spi/mcp25xxfd/mcp25xxfd_ecc.h | 16 +
drivers/net/can/spi/mcp25xxfd/mcp25xxfd_gpio.c | 194 +++++
drivers/net/can/spi/mcp25xxfd/mcp25xxfd_gpio.h | 16 +
drivers/net/can/spi/mcp25xxfd/mcp25xxfd_int.c | 73 ++
drivers/net/can/spi/mcp25xxfd/mcp25xxfd_int.h | 15 +
drivers/net/can/spi/mcp25xxfd/mcp25xxfd_priv.h | 83 +++
drivers/net/can/spi/mcp25xxfd/mcp25xxfd_regs.h | 661 +++++++++++++++++
37 files changed, 6378 insertions(+)
create mode 100644 Documentation/devicetree/bindings/net/can/microchip,mcp25xxfd.txt
create mode 100644 drivers/net/can/spi/mcp25xxfd/Kconfig
create mode 100644 drivers/net/can/spi/mcp25xxfd/Makefile
create mode 100644 drivers/net/can/spi/mcp25xxfd/mcp25xxfd_base.c
create mode 100644 drivers/net/can/spi/mcp25xxfd/mcp25xxfd_base.h
create mode 100644 drivers/net/can/spi/mcp25xxfd/mcp25xxfd_can.c
create mode 100644 drivers/net/can/spi/mcp25xxfd/mcp25xxfd_can.h
create mode 100644 drivers/net/can/spi/mcp25xxfd/mcp25xxfd_can_debugfs.c
create mode 100644 drivers/net/can/spi/mcp25xxfd/mcp25xxfd_can_debugfs.h
create mode 100644 drivers/net/can/spi/mcp25xxfd/mcp25xxfd_can_fifo.c
create mode 100644 drivers/net/can/spi/mcp25xxfd/mcp25xxfd_can_fifo.h
create mode 100644 drivers/net/can/spi/mcp25xxfd/mcp25xxfd_can_id.h
create mode 100644 drivers/net/can/spi/mcp25xxfd/mcp25xxfd_can_int.c
create mode 100644 drivers/net/can/spi/mcp25xxfd/mcp25xxfd_can_int.h
create mode 100644 drivers/net/can/spi/mcp25xxfd/mcp25xxfd_can_priv.h
create mode 100644 drivers/net/can/spi/mcp25xxfd/mcp25xxfd_can_rx.c
create mode 100644 drivers/net/can/spi/mcp25xxfd/mcp25xxfd_can_rx.h
create mode 100644 drivers/net/can/spi/mcp25xxfd/mcp25xxfd_can_tx.c
create mode 100644 drivers/net/can/spi/mcp25xxfd/mcp25xxfd_can_tx.h
create mode 100644 drivers/net/can/spi/mcp25xxfd/mcp25xxfd_clock.c
create mode 100644 drivers/net/can/spi/mcp25xxfd/mcp25xxfd_clock.h
create mode 100644 drivers/net/can/spi/mcp25xxfd/mcp25xxfd_cmd.c
create mode 100644 drivers/net/can/spi/mcp25xxfd/mcp25xxfd_cmd.h
create mode 100644 drivers/net/can/spi/mcp25xxfd/mcp25xxfd_crc.c
create mode 100644 drivers/net/can/spi/mcp25xxfd/mcp25xxfd_crc.h
create mode 100644 drivers/net/can/spi/mcp25xxfd/mcp25xxfd_debugfs.c
create mode 100644 drivers/net/can/spi/mcp25xxfd/mcp25xxfd_debugfs.h
create mode 100644 drivers/net/can/spi/mcp25xxfd/mcp25xxfd_ecc.c
create mode 100644 drivers/net/can/spi/mcp25xxfd/mcp25xxfd_ecc.h
create mode 100644 drivers/net/can/spi/mcp25xxfd/mcp25xxfd_gpio.c
create mode 100644 drivers/net/can/spi/mcp25xxfd/mcp25xxfd_gpio.h
create mode 100644 drivers/net/can/spi/mcp25xxfd/mcp25xxfd_int.c
create mode 100644 drivers/net/can/spi/mcp25xxfd/mcp25xxfd_int.h
create mode 100644 drivers/net/can/spi/mcp25xxfd/mcp25xxfd_priv.h
create mode 100644 drivers/net/can/spi/mcp25xxfd/mcp25xxfd_regs.h
--
2.11.0
