Busy loops that poll on a register should call cpu_relax(). On some
architectures, it can lower CPU power consumption or yield to a
hyperthreaded twin processor. It also serves as a compiler barrier,
so it can replace barrier() calls.
Signed-off-by: Timur Tabi <timur@codeaurora.org>
Reviewed-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Use a single common table of struct earlycon_id for both command line
and devicetree. Re-define OF_EARLYCON_DECLARE() macro to instance a
unique earlycon declaration (the declaration is only guaranteed to be
unique within a compilation unit; separate compilation units must still
use unique earlycon names).
The semantics of OF_EARLYCON_DECLARE() is different; it declares an
earlycon which can matched either on the command line or by devicetree.
EARLYCON_DECLARE() is semantically unchanged; it declares an earlycon
which is matched by command line only. Remove redundant instances of
EARLYCON_DECLARE().
This enables all earlycons to properly initialize struct console
with the appropriate name and index, which improves diagnostics and
enables direct earlycon-to-console handoff.
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Instead of defining a new field in the uart_amba_port structure, use the
existing iotype field of the uart_port structure, which is intended for
this purpose. If we need to use 32-bit register access, we set iotype
to UPIO_MEM32, otherwise we set it to UPIO_MEM.
For early console, specify the "mmio32" option on the kernel command-line.
Example:
earlycon=pl011,mmio32,0x3ced1000
Signed-off-by: Timur Tabi <timur@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The REG_x macros are indices into a table, not register offsets. Since earlycon
does not have access to the vendor data, we can currently only support standard
ARM PL011 devices.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Tested-by: Huang Shijie <shijie.huang@arm.com>
Signed-off-by: Timur Tabi <timur@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Using relaxed IO accessors allows GCC to better optimise this code
as we eliminate the heavy memory barriers - for example, GCC can now
cache the address of a register across a read-modify-write sequence,
rather than reloading the base address, offset and access size flag.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add (incomplete) support for the ZTE UART to the AMBA PL011 driver.
This is similar to the ARM and ST variants, except it has a different
register address layout, and requires 32-bit accesses to the registers.
Use the newly introduced register tables and access size support to
cope with these differences.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add support for 32-bit register accesses to the AMBA PL011 UART. This
is needed for ZTE UARTs, which require 32-bit accesses as opposed to
the more normal 16-bit accesses.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Remove the ST micro registers from the standard table. These registers
should never be accessed in non-ST micro variants.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
As we can detect when the LCR register is split between TX and RX,
we don't need three entries in the table to deal with this. Reduce
this down to two entries by converting the REG_ST_LCRH_* entries to
standard REG_LCRH_* and remove REG_LCRH.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add the ST variant register offset table to the driver. Currently,
this is an identical copy of the standard version, but this will be
modified in the following changes.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add the register offset table to the vendor data, allowing vendor
differences to be described in this table.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add a register lookup table, which allows the register offsets to be
adjusted on a per-port basis.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Prepare for REG_* register accessors. This change involves introducing
pl011_reg_to_offset() to convert REG_* to the hardware register offset,
and converting all call sites to use REG_* names. We need to fix up
locations where we check for equivalence of register offsets as well.
Much of this change was made via these sed expressions:
s/ST_UART01[1x]\(_[^_]*\|_LCRH_[TR]X\)\>/REG_ST\1/
s/UART01[1x]_\(DR\|RSR\|ECR\|FR\|ILPR\|[IF]BRD\|LCRH\|CR\|IFLS\|IMSC\|RIS\|MIS\|ICR\|DMACR\)\>/REG_\1/g
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add a helper to detect the split LCRH register found on ST variants.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Convert the new accessor functions to take the uart_amba_port instead
of the port base address.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add register accessor functions to amba-pl011. Much of this
transformation was done using the sed expression below, with any
left-overs fixed up manually afterwards, and code formatted to remain
within coding style.
s/readw(\(uap->port.membase\|regs\|port->membase\) +/pl011_read(\1,/g
s/writew(\(.*\) +/pl011_write(\1,/g
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The UART_DUMMY_DR_RX status bit is equal to (1 << 16), so a u16 is too small
to hold that value. The result is that UART_DUMMY_DR_RX is never passed
to uart_insert_char(). This means that we're always accepting characters,
even when CREAD (in termios) is not set.
Signed-off-by: Timur Tabi <timur@codeaurora.org>
Reviewed-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit 534e14e229 as with
this patch the serial console is broken on lots of platforms.
Reported-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: Jun Nie <jun.nie@linaro.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Tested-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit 7b753f318d as with
this patch the serial console is broken on lots of platforms.
Reported-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: Jun Nie <jun.nie@linaro.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Tested-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit 2c096a9eed as with
this patch the serial console is broken on lots of platforms.
Reported-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: Jun Nie <jun.nie@linaro.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Tested-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit 09dcc7dfc0 as with
this patch the serial console is broken on lots of platforms.
Reported-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: Jun Nie <jun.nie@linaro.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Tested-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit 8cd90e50d1 as with
this patch the serial console is broken on lots of platforms.
Reported-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: Jun Nie <jun.nie@linaro.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Tested-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Support ZTE uart with some registers differing offset.
Probe as platform device for not AMBA IP ID is
available on ZTE uart.
Signed-off-by: Jun Nie <jun.nie@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Improve LCRH register access decision as ARM PL011 lcrh
register serve as both TX and RX, while other SOC may
implement TX and RX function with separated register.
Signed-off-by: Jun Nie <jun.nie@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Introduce register look up table as different SOC venders
may have different register offset for the some register.
Signed-off-by: Jun Nie <jun.nie@linaro.org>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Introduce register accessor to ease loop up table access
in later patch.
Signed-off-by: Jun Nie <jun.nie@linaro.org>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Rename regs with enumeration to generalize register names.
Signed-off-by: Jun Nie <jun.nie@linaro.org>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Jun Nie <jun.nie@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Value returned by devm_ioremap_resource() was checked for non-NULL but
devm_ioremap_resource() returns IOMEM_ERR_PTR, not NULL. In case of
error this could lead to dereference of ERR_PTR.
Signed-off-by: Krzysztof Kozlowski <k.kozlowski.k@gmail.com>
Cc: <stable@vger.kernel.org>
Fixes: 3873e2d7f6 ("drivers: PL011: refactor pl011_probe()")
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add the necessary driver boilerplate to let the driver be used when
the respective ACPI table is discovered by the ACPI subsystem.
[Andre: change table name, add MODULE_DEVICE_TABLE entry and improve
commit message]
Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Graeme Gregory <graeme.gregory@linaro.org>
Tested-by: Mark Langsdorf <mlangsdo@redhat.com>
Tested-by: Naresh Bhat <nbhat@cavium.com>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The ARM Server Base System Architecture[1] document describes a
generic UART which is a subset of the PL011 UART.
It lacks DMA support, baud rate control and modem status line
control, among other things.
The idea is to move the UART initialization and setup into the
firmware (which does this job today already) and let the kernel just
use the UART for sending and receiving characters.
We use the recent refactoring to build a new struct uart_ops
variable which points to some new functions avoiding access to the
missing registers. We reuse as much existing PL011 code as possible.
In contrast to the PL011 the SBSA UART does not define any AMBA or
PrimeCell relations, so we go with a pretty generic probe function
which only uses platform device functions.
A DT binding is provided with this patch, ACPI support is added in a
separate one.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Tested-by: Mark Langsdorf <mlangsdo@redhat.com>
Tested-by: Naresh Bhat <nbhat@cavium.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The SBSA UART has a fixed baud rate and flow control setting, which
cannot be changed or queried by software.
Add a vendor specific property to always return fixed values when
trying to read the console options.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Tested-by: Mark Langsdorf <mlangsdo@redhat.com>
Tested-by: Naresh Bhat <nbhat@cavium.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The SBSA UART should not be enabled or disabled (it is always on),
and consequently the spec lacks the UART_CR register.
Add a vendor specific property to skip disabling or enabling of the
UART. This will be used later by the SBSA UART support.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Tested-by: Mark Langsdorf <mlangsdo@redhat.com>
Tested-by: Naresh Bhat <nbhat@cavium.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To avoid lines with more than 80 characters and to make the
pl011_int() function more readable, move the workaround out into a
separate function.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Tested-by: Mark Langsdorf <mlangsdo@redhat.com>
Tested-by: Naresh Bhat <nbhat@cavium.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The PL011 register UART_MIS is actually a bitwise AND of the
UART_RIS and the UART_MISC register.
Since the SBSA UART does not include the _MIS register, use the
two separate registers to get the same behaviour. Since we are
inside the spinlock and we read the _IMSC register only once, there
should be no race issue.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Tested-by: Mark Langsdorf <mlangsdo@redhat.com>
Tested-by: Naresh Bhat <nbhat@cavium.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Currently the pl011_probe() function is relying on some AMBA IDs
and a device tree node to initialize the driver and a port.
Both features are not necessarily required for the driver:
- we lack AMBA IDs in the ARM SBSA generic UART and
- we lack a DT node in ACPI systems.
So lets refactor the function to ease later reuse.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Tested-by: Mark Langsdorf <mlangsdo@redhat.com>
Tested-by: Naresh Bhat <nbhat@cavium.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Split the pl011_set_termios() function into smaller chunks to allow
easier reuse later when adding SBSA support.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Tested-by: Mark Langsdorf <mlangsdo@redhat.com>
Tested-by: Naresh Bhat <nbhat@cavium.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Split the pl011_shutdown() function into smaller chunks to allow
easier reuse later when adding SBSA support.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Tested-by: Mark Langsdorf <mlangsdo@redhat.com>
Tested-by: Naresh Bhat <nbhat@cavium.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Split the pl011_startup() function into smaller chunks to allow
easier reuse later when adding SBSA support.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Tested-by: Mark Langsdorf <mlangsdo@redhat.com>
Tested-by: Naresh Bhat <nbhat@cavium.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Although we care about not unregistering the driver if there are
still ports connected during the .remove callback, we do miss this
check in the pl011_probe function. So if the current port allocation
fails, but there are other ports already registered, we will kill
those.
So factor out the port removal into a separate function and use that
in the probe function, too.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Tested-by: Mark Langsdorf <mlangsdo@redhat.com>
Tested-by: Naresh Bhat <nbhat@cavium.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In commit 02730d3c05
(Merge 4.1-rc4 into tty-next), git mismerged some lines,
reintroducing a reference to the removed field
uart_amba_port.tx_irq_seen. This causes a build failure.
This patch removes the mismerged lines, restoring the code to what
was in tty-next (which was the intention).
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit f2ee6dfa0e.
Jakub Kiciński observed that this patch can cause the pl011
driver to hang if if the only process with a pl011 port open is
killed by a signal, pl011_shutdown() can get called with an
arbitrary amount of data still in the FIFO.
Calling _shutdown() with the TX FIFO non-empty is questionable
behaviour and my itself be a bug.
Since the affected patch was speculative anyway, and brings limited
benefit, the simplest course is to remove the assumption that TXIS
will always be left asserted after the port is shut down.
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Commit 734745c serial/amba-pl011: Activate TX IRQ passively
adds some complexity and overhead in the form of a softirq
mechanism for transmitting in the absence of interrupts.
This patch simplifies the code flow to reduce the reliance on
subtle behaviour and avoid fragility under future maintenance.
To this end, the TX softirq mechanism is removed and instead
pl011_start_tx() will now simply stuff the FIFO until full
(guaranteeing future TX IRQs), or until there are no more chars
to write (in which case we don't care whether an IRQ happens).
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Jakub Kicinski <kubakici@wp.pl>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit f2ee6dfa0e.
Jakub Kiciński observed that this patch can cause the pl011
driver to hang if if the only process with a pl011 port open is
killed by a signal, pl011_shutdown() can get called with an
arbitrary amount of data still in the FIFO.
Calling _shutdown() with the TX FIFO non-empty is questionable
behaviour and my itself be a bug.
Since the affected patch was speculative anyway, and brings limited
benefit, the simplest course is to remove the assumption that TXIS
will always be left asserted after the port is shut down.
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Unacceptable levels of debug info will happen when the DMA driver defined in
the DT/ACPI is a blacklisted module.
Another cause for log polution would be the defer probing of the DMA driver
taking too long - in which case the message that this commit removes would be
cluttering the logs due to the init daemons activity.
Signed-off-by: Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Fix a race condition that happens when device_initcall(pl011_dma_initicall)
is executed before all the devices have been probed - this issue was observed on
a hisi_6220 SoC (HiKey board from Linaro).
The deferred driver probing framework relies on late_initcall to trigger
deferred probes so it is just possible that, even with a valid DMA driver ready
to be loaded, we fail to synchronize with it.
The proposed implementation delays probing the DMA until dma_startup.
As this is invoked on port startup and port resume - but DMA probing is only
required once - we avoid calling multiple times using a new field in
uart_amba_port to track this scenario.
This commit allows for subsequent attempts to associate an external DMA if the
DMA driver itself is not available (but present in the deferred probe pending
list).
Signed-off-by: Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Getting the TX IRQ re-asserted from scratch can be inefficient in
some setups.
This patch avoids clearing the TX IRQ across pl011_shutdown()...
pl011_startup(), so that if the port is closed and reopened, the
IRQ will still work afterwards without having to bootstrap it again.
The TX IRQ continues to be masked in IMSC when the UART is not in
use.
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Tested-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The current PL011 driver transmits a dummy character when the UART
is opened, to assert the TX IRQ for the first time
(see pl011_startup()). The UART is put in loopback mode temporarily,
so the receiver presumably shouldn't see anything.
However...
At least some platforms containing a PL011 send characters down the
wire even when loopback mode is enabled. This means that a
spurious NUL character may be seen at the receiver when the PL011 is
opened through the TTY layer.
The current code also temporarily sets the baud rate to maximum and
the character width to the minimum, to that the dummy TX completes
as quickly as possible. If this is seen by the receiver it will
result in a framing error and can knock the receiver out of sync --
turning subsequent output into garbage until synchronisation
is reestablished. (Particularly problematic during boot with systemd.)
To avoid spurious transmissions, this patch removes assumptions about
whether the TX IRQ will fire until at least one TX IRQ has been seen.
Instead, the UART will unmask the TX IRQ and then slow-start via
polling and timer-based soft IRQs initially. If the TTY layer writes
enough data to fill the FIFO to the interrupt threshold in one go,
the TX IRQ should assert, at which point the driver changes to
fully interrupt-driven TX.
In this way, the TX IRQ is activated as a side-effect instead of
being done deliberately.
This should also mean that the driver works on the SBSA Generic
UART[1] (a cut-down PL011) without invasive changes. The Generic
UART lacks some features needed for the dummy TX approach to work
(FIFO disabling and loopback).
[1] Server Base System Architecture (ARM-DEN-0029-v2.3)
http://infocenter.arm.com/
(click-thru required :/)
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Tested-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add equivalent attributes to those provided in the platform data
for use when RX DMA is enabled.
Signed-off-by: Andrew Jackson <Andrew.Jackson@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
If the DMA engine doesn't support residue processing then the RX DMA
handling won't work terribly well if polling is enabled. So, disable
RX DMA if residue handling isn't available.
Signed-off-by: Andrew Jackson <Andrew.Jackson@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
