As reported by a comment in the c_can_start_xmit() this was not a FIFO.
C/D_CAN controller sends out the buffers prioritized so that the lowest
buffer number wins.
What did c_can_start_xmit() do if head was less tail in the tx ring ? It
waited until all the frames queued in the FIFO was actually transmitted
by the controller before accepting a new CAN frame to transmit, even if
the FIFO was not full, to ensure that the messages were transmitted in
the order in which they were loaded.
By storing the frames in the FIFO without requiring its transmission, we
will be able to use the full size of the FIFO even in cases such as the
one described above. The transmission interrupt will trigger their
transmission only when all the messages previously loaded but stored in
less priority positions of the buffers have been transmitted.
Link: https://lore.kernel.org/r/20210807130800.5246-5-dariobin@libero.it
Suggested-by: Gianluca Falavigna <gianluca.falavigna@inwind.it>
Signed-off-by: Dario Binacchi <dariobin@libero.it>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
The algorithm is already used successfully by other CAN drivers
(e.g. mcp251xfd). Its implementation was kindly suggested to me by
Marc Kleine-Budde following a patch I had previously submitted. You can
find every detail at https://lore.kernel.org/patchwork/patch/1422929/.
The idea is that after this patch, it will be easier to patch the driver
to use the message object memory as a true FIFO.
Link: https://lore.kernel.org/r/20210807130800.5246-4-dariobin@libero.it
Suggested-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Dario Binacchi <dariobin@libero.it>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
With commit 132f2d45fb ("can: c_can: add support to 64 message
objects") the number of message objects used for reception /
transmission depends on FIFO size.
The ethtools API support allows you to retrieve this info. Driver info
has been added too.
Link: https://lore.kernel.org/r/20210514165549.14365-2-dariobin@libero.it
Signed-off-by: Dario Binacchi <dariobin@libero.it>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
The member rxmasked of struct c_can_priv is initialized by
c_can_chip_config(), but's it's never used, so remove it.
Link: https://lore.kernel.org/r/20210509124309.30024-2-dariobin@libero.it
Signed-off-by: Dario Binacchi <dariobin@libero.it>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
D_CAN controller supports 16, 32, 64 or 128 message objects, comparing
to 32 on C_CAN. AM335x/AM437x Sitara processors and DRA7 SOC all
instantiate a D_CAN controller with 64 message objects, as described
in the "DCAN features" subsection of the CAN chapter of their
technical reference manuals.
The driver policy has been kept unchanged, and as in the previous
version, the first half of the message objects is used for reception
and the second for transmission.
The I/O load is increased only in the case of 64 message objects,
keeping it unchanged in the case of 32. Two 32-bit read accesses are
in fact required, which however remained at 16-bit for configurations
with 32 message objects.
Link: https://lore.kernel.org/r/20210302215435.18286-7-dariobin@libero.it
Signed-off-by: Dario Binacchi <dariobin@libero.it>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
As pointed by commit c0a9f4d396 ("can: c_can: Reduce register
access") the "driver casts the 16 message objects in stone, which is
completely braindead as contemporary hardware has up to 128 message
objects".
The patch prepares the module to extend the number of message objects
beyond the 32 currently managed. This was achieved by transforming the
constants used to manage RX/TX messages into variables without
changing the driver policy.
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/r/20210302215435.18286-6-dariobin@libero.it
Signed-off-by: Dario Binacchi <dariobin@libero.it>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Commit 9d23a9818c ("can: c_can: Remove unused inline function") left
behind C_CAN_MSG_OBJ_TX_LAST constant.
Commit fa39b54ccf ("can: c_can: Get rid of pointless interrupts") left
behind C_CAN_MSG_RX_LOW_LAST and C_CAN_MSG_OBJ_RX_SPLIT constants.
The removed code also made a comment useless and misleading.
Link: https://lore.kernel.org/r/20210302215435.18286-2-dariobin@libero.it
Signed-off-by: Dario Binacchi <dariobin@libero.it>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
This patch marks the arrays reg_map_c_can and reg_map_d_can as __maybe_unused,
as they are indeed unused in the c_can driver. This warning shows up, when
compiling the kernel with "W=1":
drivers/net/can/c_can/c_can.c:45:
drivers/net/can/c_can/c_can.h:124:18: warning: ‘reg_map_d_can’ defined but not used [-Wunused-const-variable=]
drivers/net/can/c_can/c_can.h:84:18: warning: ‘reg_map_c_can’ defined but not used [-Wunused-const-variable=]
Link: http://lore.kernel.org/r/20201006203748.1750156-4-mkl@pengutronix.de
Fixes: 33f8100977 ("can: c_can: Move overlay structure to array with offset as index")
Fixes: 69927fccd9 ("can: c_can: Add support for Bosch D_CAN controller")
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
When the status register is read without the status IRQ pending, the
chip may not raise the interrupt line for an upcoming status interrupt
and the driver may miss a status interrupt.
It is critical that the BUSOFF status interrupt is forwarded to the
higher layers, since no more interrupts will follow without
intervention.
Thanks to Wolfgang and Joe for bringing up the first idea.
Signed-off-by: Kurt Van Dijck <dev.kurt@vandijck-laurijssen.be>
Cc: Wolfgang Grandegger <wg@grandegger.com>
Cc: Joe Burmeister <joe.burmeister@devtank.co.uk>
Fixes: fa39b54ccf ("can: c_can: Get rid of pointless interrupts")
Cc: linux-stable <stable@vger.kernel.org>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Some SoCs e.g. (TI DRA7xx) need a START pulse to start the
RAMINIT sequence i.e. START bit must be set and cleared before
checking for the DONE bit status.
Signed-off-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Some TI SoCs like DRA7 have a RAMINIT register specification
different from the other AMxx SoCs and as expected by the
existing driver.
To add more insanity, this register is shared with other
IPs like DSS, PCIe and PWM.
Provides a more generic mechanism to specify the RAMINIT
register location and START/DONE bit position and use the
syscon/regmap framework to access the register.
Signed-off-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Some platforms (e.g. TI) need special RAMINIT register handling.
Provide a way to store RAMINIT register description in driver data.
Signed-off-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
We want to have more data than just can_dev_id to be present
in the driver data e.g. TI platforms need RAMINIT register
description. Introduce the c_can_driver_data structure and move
the can_dev_id into it.
Tidy up the way it is used on probe().
Signed-off-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Add helpers for 32-bit accesses and replace open-coded 32-bit access
with calls to helpers. Minimum changes are done to the pci case, as I
don't have access to that hardware.
Tested-by: Thor Thayer <tthayer@altera.com>
Signed-off-by: Thor Thayer <tthayer@altera.com>
Signed-off-by: Pavel Machek <pavel@denx.de>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
This patch makes the {read,write}_reg functions const, this is a preparation to
make use of {read,write}_reg in the hwinit callback.
Signed-off-by: Thor Thayer <tthayer@altera.com>
Signed-off-by: Pavel Machek <pavel@denx.de>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Commit 6439fbce10 (can: c_can: fix error checking of priv->instance in
probe()) found the warning but applied a suboptimal solution. Since, both
pdev->id and of_alias_get_id() return integers, it makes sense to convert the
variable to an integer and avoid the cast.
Signed-off-by: Wolfram Sang <wsa@sang-engineering.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
It's suffcient to kill the TXIE bit in the message control register
even if the documentation of C and D CAN says that it's not allowed to
do that while MSGVAL is set. Reality tells a different story and this
change gives us another 2% of CPU back for not waiting on I/O.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Alexander Stein <alexander.stein@systec-electronic.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Mark suggested to use one IF for the softirq and the other for the
xmit function to avoid the xmit lock.
That requires to write the frame into the interface first, then handle
the echo skb and store the dlc before committing the TX request to the
message ram.
We use an atomic to handle the active buffers instead of reading the
MSGVAL register as thats way faster especially on PCH/x86.
Suggested-by: Mark <mark5@del-llc.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Alexander Stein <alexander.stein@systec-electronic.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Remove the MASK from the TX transfer side.
Make the code readable and get rid of the annoying IFX_WRITE_XXX_16BIT
macros which are just obfuscating the code.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Alexander Stein <alexander.stein@systec-electronic.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Alexander reported that the new optimized handling of the RX fifo
causes random packet loss on Intel PCH C_CAN hardware.
After a few fruitless debugging sessions I got hold of a PCH (eg20t)
afflicted system. That machine does not have the CAN interface wired
up, but it was possible to reproduce the issue with the HW loopback
mode.
As Alexander observed correctly, clearing the NewDat flag along with
reading out the message buffer causes that issue on C_CAN, while D_CAN
handles that correctly.
Instead of restoring the original message buffer handling horror the
following workaround solves the issue:
transfer buffer to IF without clearing the NewDat
handle the message
clear NewDat bit
That's similar to the original code but conditional for C_CAN.
I really wonder why all user manuals (C_CAN, Intel PCH and some more)
recommend to clear the NewDat bit right away. The knows it all Oracle
operated by Gurgle does not unearth any useful information either. I
simply cannot believe that we are the first to uncover that HW issue.
Reported-and-tested-by: Alexander Stein <alexander.stein@systec-electronic.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
The driver handles pointlessly TWO interrupts per packet. The reason
is that it enables the status interrupt which fires for each rx and tx
packet and it enables the per message object interrupts as well.
The status interrupt merily acks or in case of D_CAN ignores the TX/RX
state and then the message object interrupt fires.
The message objects interrupts are only useful if all message objects
have hardware filters activated.
But we don't have that and its not simple to implement in that driver
without rewriting it completely.
So we can ditch the message object interrupts and handle the RX/TX
right away from the status interrupt. Instead of TWO we handle ONE.
Note: We must keep the TXIE/RXIE bits in the message buffers because
the status interrupt alone is not reliable enough in corner cases.
If we ever have the need for HW filtering, then this code needs a
complete overhaul and we can think about it then. For now we prefer a
lower interrupt load.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Alexander Stein <alexander.stein@systec-electronic.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
We can avoid the HW access in TX cleanup path for retrieving the DLC
of the sent package if we store the DLC in a private array.
Ideally this should be handled in the can_echo_skb functions, but I
leave that exercise to the CAN folks.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
The network core does not serialize the access to the hardware. The
xmit related code lets the following happen:
CPU0 CPU1
interrupt()
do_poll()
c_can_do_tx()
Fiddle with HW and xmit()
internal data Fiddle with HW and
internal data
due the complete lack of serialization.
Add proper locking.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Add D_CAN raminit support to C_CAN driver to enable D_CAN RAM,
which holds all the message objects during transmission or
receiving of data. This initialization/de-initialization should
be done in synchronous with D_CAN clock.
In case of AM335X-EVM (current user of D_CAN driver) message RAM is
controlled through control module register for both instances. So
control module register details is required to initialization or
de-initialization of message RAM according to instance number.
Control module memory resource is obtained from D_CAN dt node and
instance number obtained from device tree aliases node.
This patch was tested on AM335x-EVM along with pinctrl data addition
patch, d_can dt aliases addition and control module data addition.
pinctrl data addition is not added to am335x-evm.dts (only supports
CPLD profile#0) because d_can1 is supported under CPLD profile#1.
Signed-off-by: AnilKumar Ch <anilkumar@ti.com>
[mkl: fix instance for non DT in probe, cleaned up raminit]
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Adds suspend resume support to DCAN driver which enables
DCAN power down mode bit (PDR). Then DCAN will ack the local
power-down mode by setting PDA bit in STATUS register.
Signed-off-by: AnilKumar Ch <anilkumar@ti.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Add Runtime PM support to C_CAN/D_CAN controller. The runtime PM
APIs control clocks for C_CAN/D_CAN IP and prevent access to the
register of C_CAN/D_CAN IP when clock is turned off.
Signed-off-by: AnilKumar Ch <anilkumar@ti.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Modify c_can device names from *_CAN_DEVTYPE to BOSCH_*_CAN to make
use of same names for array indexes in c_can_id_table[] as well as
device names.
This patch also add indexes to c_can_id_table array.
Signed-off-by: AnilKumar Ch <anilkumar@ti.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
This patch adds the support for D_CAN controller driver to the existing
C_CAN driver.
Bosch D_CAN controller is a full-CAN implementation which is compliant
to CAN protocol version 2.0 part A and B. Bosch D_CAN user manual can be
obtained from: http://www.semiconductors.bosch.de/media/en/pdf/
ipmodules_1/can/d_can_users_manual_111.pdf
A new array is added for accessing the d_can registers, according to d_can
controller register space.
Current D_CAN implementation has following limitations, this is done
to avoid large changes to the C_CAN driver.
1. Message objects are limited to 32, 16 for RX and 16 for TX. C_CAN IP
supports upto 32 message objects but in case of D_CAN we can configure
upto 128 message objects.
2. Using two 16bit reads/writes for accessing the 32bit D_CAN registers.
3. These patches have been tested on little endian machine, there might
be some hidden endian-related issues due to the nature of the accesses
(32-bit registers accessed as 2 16-bit registers). However, I do not
have a big-endian D_CAN implementation to confirm.
Signed-off-by: AnilKumar Ch <anilkumar@ti.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
c_can uses overlay structure for accessing c_can module registers.
With this kind of implementation it is difficult to add one more ip
which is similar to c_can in functionality but different register
offsets.
This patch changes the overlay structure implementation to an array
with register offset as index. This way we can overcome the above
limitation.
Signed-off-by: AnilKumar Ch <anilkumar@ti.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
This patch fixes an interrupt thrash issue with c_can driver.
In c_can_isr() function interrupts are disabled and enabled only in
c_can_poll() function. c_can_isr() & c_can_poll() both read the
irqstatus flag. However, irqstatus is always read as 0 in c_can_poll()
because all C_CAN interrupts are disabled in c_can_isr(). This causes
all interrupts to be re-enabled in c_can_poll() which in turn causes
another interrupt since the event is not really handled. This keeps
happening causing a flood of interrupts.
To fix this, read the irqstatus register in isr and use the same cached
value in the poll function.
Cc: stable@kernel.org # 2.6.39+
Signed-off-by: AnilKumar Ch <anilkumar@ti.com>
Acked-by: Wolfgang Grandegger <wg@grandegger.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Bosch C_CAN controller is a full-CAN implementation which is compliant
to CAN protocol version 2.0 part A and B. Bosch C_CAN user manual can be
obtained from:
http://www.semiconductors.bosch.de/media/en/pdf/ipmodules_1/c_can/users_manual_c_can.pdf
This patch adds the support for this controller.
The following are the design choices made while writing the controller
driver:
1. Interface Register set IF1 has be used only in the current design.
2. Out of the 32 Message objects available, 16 are kept aside for RX
purposes and the rest for TX purposes.
3. NAPI implementation is such that both the TX and RX paths function
in polling mode.
Signed-off-by: Bhupesh Sharma <bhupesh.sharma@st.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
