serial: 8250_bcm7271: Switch to use uart_read_port_properties()

Since we have now a common helper to read port properties
use it instead of sparse home grown solution.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Tested-by: Florian Fainelli <florian.fainelli@broadcom.com>
Link: https://lore.kernel.org/r/20240304123035.758700-7-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: 8250_bcm7271: Replace custom unit definitions

Replace custom unit definitions that are available via units.h.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Link: https://lore.kernel.org/r/20240215160234.653305-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: 8250: Convert to platform remove callback returning void

The .remove() callback for a platform driver returns an int which makes
many driver authors wrongly assume it's possible to do error handling by
returning an error code. However the value returned is ignored (apart
from emitting a warning) and this typically results in resource leaks.

To improve here there is a quest to make the remove callback return
void. In the first step of this quest all drivers are converted to
.remove_new(), which already returns void. Eventually after all drivers
are converted, .remove_new() will be renamed to .remove().

Trivially convert this driver from always returning zero in the remove
callback to the void returning variant.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com> # 8250_bcm*
Link: https://lore.kernel.org/r/20231110152927.70601-4-u.kleine-koenig@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: 8250_bcm7271: Use devm_clk_get_optional_enabled()

Use devm_clk_get_optional_enabled() to simplify the code.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://lore.kernel.org/r/20231005124550.3607234-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: 8250_bcm7271: Use dev_err_probe() instead of dev_err()

Make the error messages format unified by switching to use
dev_err_probe() where it makes sense.

This also helps simplifing the code.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Link: https://lore.kernel.org/r/20230918103648.1185663-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: 8250_bcm7271: Use port lock wrappers

When a serial port is used for kernel console output, then all
modifications to the UART registers which are done from other contexts,
e.g. getty, termios, are interference points for the kernel console.

So far this has been ignored and the printk output is based on the
principle of hope. The rework of the console infrastructure which aims to
support threaded and atomic consoles, requires to mark sections which
modify the UART registers as unsafe. This allows the atomic write function
to make informed decisions and eventually to restore operational state. It
also allows to prevent the regular UART code from modifying UART registers
while printk output is in progress.

All modifications of UART registers are guarded by the UART port lock,
which provides an obvious synchronization point with the console
infrastructure.

To avoid adding this functionality to all UART drivers, wrap the
spin_[un]lock*() invocations for uart_port::lock into helper functions
which just contain the spin_[un]lock*() invocations for now. In a
subsequent step these helpers will gain the console synchronization
mechanisms.

Converted with coccinelle. No functional change.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Link: https://lore.kernel.org/r/20230914183831.587273-6-john.ogness@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: 8250_bcm7271: improve bcm7271 8250 port

The 8250 BCM7271 UART is not a direct match to PORT_16550A and other
generic ports do not match its hardware capabilities. PORT_ALTR matches
the rx trigger levels, but its vendor configurations are not compatible.
Unfortunately this means we need to create another port to fully capture
the hardware capabilities of the BCM7271 UART.

To alleviate some latency pressures, we default the rx trigger level to 8.

Signed-off-by: Justin Chen <justin.chen@broadcom.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Acked-by: Doug Berger <opendmb@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/1692643978-16570-1-git-send-email-justin.chen@broadcom.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: 8250: lock port in startup() callbacks

uart_ops startup() callback is called without interrupts
disabled and without port->lock locked, relatively late during the
boot process (from the call path of console_on_rootfs()). If the
device is a console, it was already previously registered and could
be actively printing messages.

The console printing function serial8250_console_write() modifies
the interrupt register (UART_IER) under the port->lock with the
pattern: read, clear, restore.

Since some startup() callbacks are modifying UART_IER without the
port->lock locked, it is possible that the value intended to be
written by the startup() callback will get overwritten and be
lost.

CPU0 CPU1
serial8250_console_write omap_8250_startup
-------------------------- -----------------
spin_lock(port->lock)
oldval = read(UART_IER)
uart_console_write()
write(newval, UART_IER)
write(oldval, UART_IER)
spin_unlock(port->lock)

Add port->lock synchronization to the 8250 startup() callbacks
where they need to access UART_IER. This avoids racing with
serial8250_console_write().

Signed-off-by: John Ogness <john.ogness@linutronix.de>
Link: https://lore.kernel.org/r/20230525093159.223817-2-john.ogness@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: 8250_bcm7271: fix leak in `brcmuart_probe`

Smatch reports:
drivers/tty/serial/8250/8250_bcm7271.c:1120 brcmuart_probe() warn:
'baud_mux_clk' from clk_prepare_enable() not released on lines: 1032.

The issue is fixed by using a managed clock.

Fixes: 41a469482de2 ("serial: 8250: Add new 8250-core based Broadcom STB driver")
Reported-by: XuDong Liu <m202071377@hust.edu.cn>
Link: https://lore.kernel.org/lkml/20230424125100.4783-1-m202071377@hust.edu.cn/
Signed-off-by: Doug Berger <opendmb@gmail.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20230427181916.2983697-3-opendmb@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: 8250_bcm7271: balance clk_enable calls

The sw_baud clock must be disabled when the device driver is not
connected to the device. This now occurs when probe fails and
upon remove.

Fixes: 41a469482de2 ("serial: 8250: Add new 8250-core based Broadcom STB driver")
Reported-by: XuDong Liu <m202071377@hust.edu.cn>
Link: https://lore.kernel.org/lkml/20230424125100.4783-1-m202071377@hust.edu.cn/
Signed-off-by: Doug Berger <opendmb@gmail.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20230427181916.2983697-2-opendmb@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: 8250_bcm7271: Fix arbitration handling

The arbitration of the UART DMA is mishandled for a few
exceptional cases when probing and releasing the driver.

It is possible that the DMA register spaces are not defined in
device tree for an instance of the driver, so attempts to access
the registers in brcmuart_arbitration() would use NULL pointers.

It is also possible for the probe function to return an error
while still holding the UART DMA. This would prevent the UART
DMA from being claimed by an instance that could use it.

These errors are addressed by only releasing the UART DMA if it
is held by this instance (i.e. priv->dma_enabled == 1) and
directing early error paths in probe to this common release_dma
handling.

Fixes: 41a469482de2 ("serial: 8250: Add new 8250-core based Broadcom STB driver")
Signed-off-by: Doug Berger <opendmb@gmail.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20230309190224.687380-1-opendmb@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: 8250_bcm7271: Fix error handling in brcmuart_init()

A problem about 8250_bcm7271 create debugfs failed is triggered with the
following log given:

[ 324.516635] debugfs: Directory 'bcm7271-uart' with parent '/' already present!

The reason is that brcmuart_init() returns platform_driver_register()
directly without checking its return value, if platform_driver_register()
failed, it returns without destroy the newly created debugfs, resulting
the debugfs of 8250_bcm7271 can never be created later.

brcmuart_init()
debugfs_create_dir() # create debugfs directory
platform_driver_register()
driver_register()
bus_add_driver()
priv = kzalloc(...) # OOM happened
# return without destroy debugfs directory

Fix by removing debugfs when platform_driver_register() returns error.

Fixes: 41a469482de2 ("serial: 8250: Add new 8250-core based Broadcom STB driver")
Signed-off-by: Yuan Can <yuancan@huawei.com>
Link: https://lore.kernel.org/r/20221109072110.117291-2-yuancan@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: 8250_bcm7271: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-7-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: Make ->set_termios() old ktermios const

There should be no reason to adjust old ktermios which is going to get
discarded anyway.

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220816115739.10928-7-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: 8250_bcm7271: Save/restore RTS in suspend/resume

Commit 9cabe26e65a8 ("serial: 8250_bcm7271: UART errors after resuming
from S2") prevented an early enabling of RTS during resume, but it did
not actively restore the RTS state after resume.

Fixes: 9cabe26e65a8 ("serial: 8250_bcm7271: UART errors after resuming from S2")
Signed-off-by: Doug Berger <opendmb@gmail.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20220714031316.404918-1-f.fainelli@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: 8250_bcm7271: Fix return error code in case of dma_alloc_coherent() failure

In case of dma_alloc_coherent() failure return -ENOMEM instead of
returning -EINVAL.

Reported-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Link: https://lore.kernel.org/r/20220105180704.8989-1-prabhakar.mahadev-lad.rj@bp.renesas.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: 8250_bcm7271: Propagate error codes from brcmuart_probe()

In case of failures brcmuart_probe() always returned -ENODEV, this
isn't correct for example platform_get_irq_byname() may return
-EPROBE_DEFER to handle such cases propagate error codes in
brcmuart_probe() in case of failures.

Fixes: 41a469482de25 ("serial: 8250: Add new 8250-core based Broadcom STB driver")
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Link: https://lore.kernel.org/r/20211224142917.6966-4-prabhakar.mahadev-lad.rj@bp.renesas.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: 8250_bcm7271: Use platform_get_irq() to get the interrupt

platform_get_resource(pdev, IORESOURCE_IRQ, ..) relies on static
allocation of IRQ resources in DT core code, this causes an issue
when using hierarchical interrupt domains using "interrupts" property
in the node as this bypasses the hierarchical setup and messes up the
irq chaining.

In preparation for removal of static setup of IRQ resource from DT core
code use platform_get_irq().

Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Link: https://lore.kernel.org/r/20211224142917.6966-3-prabhakar.mahadev-lad.rj@bp.renesas.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: 8250_bcm7271: UART errors after resuming from S2

There is a small window in time during resume where the hardware
flow control signal RTS can be asserted (which allows a sender to
resume sending data to the UART) but the baud rate has not yet
been restored. This will cause corrupted data and FRAMING, OVERRUN
and BREAK errors. This is happening because the MCTRL register is
shadowed in uart_port struct and is later used during resume to set
the MCTRL register during both serial8250_do_startup() and
uart_resume_port(). Unfortunately, serial8250_do_startup()
happens before the UART baud rate is restored. The fix is to clear
the shadowed mctrl value at the end of suspend and restore it at the
end of resume.

Fixes: 41a469482de2 ("serial: 8250: Add new 8250-core based Broadcom STB driver")
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Al Cooper <alcooperx@gmail.com>
Link: https://lore.kernel.org/r/20211201201402.47446-1-alcooperx@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: 8250_bcm7271: use NULL to initialized a null pointer

Pointer membase is currently being in initialized with zero rather
than NULL. Fix this.

Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Link: https://lore.kernel.org/r/20210719095533.14017-1-colin.king@canonical.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: 8250: Make symbol 'brcmuart_debugfs_root' static

symbol 'brcmuart_debugfs_root' is not used outside of 8250_bcm7271.c,
so this commit marks it static.

Signed-off-by: Zucheng Zheng <zhengzucheng@huawei.com>
Link: https://lore.kernel.org/r/20210401074919.56573-1-zhengzucheng@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: 8250_bcm7271: Fix return value check in brcmuart_probe()

In case of error, the function devm_ioremap() returns NULL
pointer not ERR_PTR(). The IS_ERR() test in the return value
check should be replaced with NULL test.

Fixes: 41a469482de2 ("serial: 8250: Add new 8250-core based Broadcom STB driver")
Reported-by: Hulk Robot <hulkci@huawei.com>
Reviewed-by: Al Cooper <alcooperx@gmail.com>
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Link: https://lore.kernel.org/r/20210329140659.1832950-1-weiyongjun1@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: 8250: Add new 8250-core based Broadcom STB driver

Add a UART driver for the new Broadcom 8250 based STB UART. The new
UART is backward compatible with the standard 8250, but has some
additional features. The new features include a high accuracy baud
rate clock system and DMA support.

The driver will use the new optional BAUD MUX clock to select the best
one of the four master clocks (81MHz, 108MHz, 64MHz and 48MHz) to feed
the baud rate selection logic for any requested baud rate. This allows
for more accurate BAUD rates when high speed baud rates are selected.

The driver will use the new UART DMA hardware if the UART DMA registers
are specified in Device Tree "reg" property.

The driver also sets the UPSTAT_AUTOCTS flag when hardware flow control
is enabled. This flag is needed for UARTs that don't assert a CTS
changed interrupt when CTS changes and AFE (Hardware Flow Control) is
enabled.

The driver also contains a workaround for a bug in the Synopsis 8250
core. The problem is that at high baud rates, the RX partial FIFO
timeout interrupt can occur but there is no RX data (DR not set in
the LSR register). In this case the driver will not read the Receive
Buffer Register, which clears the interrupt, and the system will get
continuous UART interrupts until the next RX character arrives. The
fix originally suggested by Synopsis was to read the Receive Buffer
Register and discard the character when the DR bit in the LSR was
not set, to clear the interrupt. The problem was that occasionally
a character would arrive just after the DR bit check and a valid
character would be discarded. The fix that was added will clear
receive interrupts to stop the interrupt, deassert RTS to insure
that no new data can arrive, wait for 1.5 character times for the
sender to react to RTS and then check for data and either do a dummy
read or a valid read. Debugfs error counters were also added and were
used to help create test software that would cause the error condition.
The counters can be found at:
/sys/kernel/debug/bcm7271-uart/<device-name>/stats

This also includes a few fixes for build warnings reported by
the kernel test robot.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Al Cooper <alcooperx@gmail.com>
Link: https://lore.kernel.org/r/20210325185256.16156-3-alcooperx@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>