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: NRussell King <rmk+kernel@arm.linux.org.uk>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg 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: NRussell King <rmk+kernel@arm.linux.org.uk>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg 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: NRussell King <rmk+kernel@arm.linux.org.uk>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg 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: NRussell King <rmk+kernel@arm.linux.org.uk>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg 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: NRussell King <rmk+kernel@arm.linux.org.uk>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg 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: NRussell King <rmk+kernel@arm.linux.org.uk>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg 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: NRussell King <rmk+kernel@arm.linux.org.uk>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg 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: NRussell King <rmk+kernel@arm.linux.org.uk>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg 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: NRussell King <rmk+kernel@arm.linux.org.uk>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Add a helper to detect the split LCRH register found on ST variants.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg 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: NRussell King <rmk+kernel@arm.linux.org.uk>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg 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: NRussell King <rmk+kernel@arm.linux.org.uk>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg 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: NTimur Tabi <timur@codeaurora.org>
Reviewed-by: NDave Martin <Dave.Martin@arm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This reverts commit 534e14e2 as with
this patch the serial console is broken on lots of platforms.
Reported-by: NMarc Zyngier <marc.zyngier@arm.com>
Cc: Jun Nie <jun.nie@linaro.org>
Acked-by: NWill Deacon <will.deacon@arm.com>
Tested-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This reverts commit 7b753f31 as with
this patch the serial console is broken on lots of platforms.
Reported-by: NMarc Zyngier <marc.zyngier@arm.com>
Cc: Jun Nie <jun.nie@linaro.org>
Acked-by: NWill Deacon <will.deacon@arm.com>
Tested-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This reverts commit 2c096a9e as with
this patch the serial console is broken on lots of platforms.
Reported-by: NMarc Zyngier <marc.zyngier@arm.com>
Cc: Jun Nie <jun.nie@linaro.org>
Acked-by: NWill Deacon <will.deacon@arm.com>
Tested-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This reverts commit 09dcc7df as with
this patch the serial console is broken on lots of platforms.
Reported-by: NMarc Zyngier <marc.zyngier@arm.com>
Cc: Jun Nie <jun.nie@linaro.org>
Acked-by: NWill Deacon <will.deacon@arm.com>
Tested-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This reverts commit 8cd90e50 as with
this patch the serial console is broken on lots of platforms.
Reported-by: NMarc Zyngier <marc.zyngier@arm.com>
Cc: Jun Nie <jun.nie@linaro.org>
Acked-by: NWill Deacon <will.deacon@arm.com>
Tested-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NGreg 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: NJun Nie <jun.nie@linaro.org>
Signed-off-by: NGreg 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: NJun Nie <jun.nie@linaro.org>
Signed-off-by: NGreg 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: NJun Nie <jun.nie@linaro.org>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Introduce register accessor to ease loop up table access
in later patch.
Signed-off-by: NJun Nie <jun.nie@linaro.org>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Rename regs with enumeration to generalize register names.
Signed-off-by: NJun Nie <jun.nie@linaro.org>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NJun Nie <jun.nie@linaro.org>
Signed-off-by: NGreg 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: NKrzysztof Kozlowski <k.kozlowski.k@gmail.com>
Cc: <stable@vger.kernel.org>
Fixes: 3873e2d7 ("drivers: PL011: refactor pl011_probe()")
Signed-off-by: NGreg 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: NHanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: NGraeme Gregory <graeme.gregory@linaro.org>
Tested-by: NMark Langsdorf <mlangsdo@redhat.com>
Tested-by: NNaresh Bhat <nbhat@cavium.com>
Signed-off-by: NAndre Przywara <andre.przywara@arm.com>
Signed-off-by: NGreg 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: NAndre Przywara <andre.przywara@arm.com>
Tested-by: NMark Langsdorf <mlangsdo@redhat.com>
Tested-by: NNaresh Bhat <nbhat@cavium.com>
Signed-off-by: NGreg 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: NAndre Przywara <andre.przywara@arm.com>
Tested-by: NMark Langsdorf <mlangsdo@redhat.com>
Tested-by: NNaresh Bhat <nbhat@cavium.com>
Signed-off-by: NGreg 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: NAndre Przywara <andre.przywara@arm.com>
Tested-by: NMark Langsdorf <mlangsdo@redhat.com>
Tested-by: NNaresh Bhat <nbhat@cavium.com>
Signed-off-by: NGreg 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: NAndre Przywara <andre.przywara@arm.com>
Tested-by: NMark Langsdorf <mlangsdo@redhat.com>
Tested-by: NNaresh Bhat <nbhat@cavium.com>
Signed-off-by: NGreg 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: NAndre Przywara <andre.przywara@arm.com>
Tested-by: NMark Langsdorf <mlangsdo@redhat.com>
Tested-by: NNaresh Bhat <nbhat@cavium.com>
Signed-off-by: NGreg 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: NAndre Przywara <andre.przywara@arm.com>
Tested-by: NMark Langsdorf <mlangsdo@redhat.com>
Tested-by: NNaresh Bhat <nbhat@cavium.com>
Signed-off-by: NGreg 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: NAndre Przywara <andre.przywara@arm.com>
Tested-by: NMark Langsdorf <mlangsdo@redhat.com>
Tested-by: NNaresh Bhat <nbhat@cavium.com>
Signed-off-by: NGreg 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: NAndre Przywara <andre.przywara@arm.com>
Tested-by: NMark Langsdorf <mlangsdo@redhat.com>
Tested-by: NNaresh Bhat <nbhat@cavium.com>
Signed-off-by: NGreg 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: NAndre Przywara <andre.przywara@arm.com>
Tested-by: NMark Langsdorf <mlangsdo@redhat.com>
Tested-by: NNaresh Bhat <nbhat@cavium.com>
Signed-off-by: NGreg 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: NAndre Przywara <andre.przywara@arm.com>
Tested-by: NMark Langsdorf <mlangsdo@redhat.com>
Tested-by: NNaresh Bhat <nbhat@cavium.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Commit 734745ca serial/amba-pl011:
(Activate TX IRQ passively) introduces a race which causes the driver
sometimes to attempt to write a character to the TX FIFO when the FIFO
is already full.

The PL011 does not guarantee its behaviour when the FIFO is overfilled.
In practice, this can cause duplicate and/or dropped characters to be
output on the wire.  The problem is common enough to be readily
observable on the ARM Juno platform when the PL011 UART is used as
the console and DMA is not in use.

This patch fixes this problem by always polling for space before each
character is written to the FIFO.

This will be amended to a less brute-force approach in a later commit,
but this patch should help ensure correct behaviour for now.
Signed-off-by: NDave Martin <Dave.Martin@arm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

In commit 02730d3c
(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: NDave Martin <Dave.Martin@arm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This reverts commit f2ee6dfa.

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: NDave Martin <Dave.Martin@arm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Commit 734745ca 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: NDave Martin <Dave.Martin@arm.com>
Signed-off-by: NJakub Kicinski <kubakici@wp.pl>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This reverts commit f2ee6dfa.

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: NDave Martin <Dave.Martin@arm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>