serial: 8250_pci1xxxx: Drop quirk from 8250_port

We are not supposed to spread quirks in 8250_port module especially
when we have a separate driver for the hardware in question.

Move quirk from generic module to the driver that uses it.

While at it, move IO to ->set_divisor() callback as it has to be from
day 1. ->get_divisor() is not supposed to perform any IO as UART port:
- might not be powered on
- is not locked by a spin lock

Fixes: 1ed67ecd1349 ("8250: microchip: Add 4 Mbps support in PCI1XXXX UART")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Rengarajan S <rengarajan.s@microchip.com>
Link: https://lore.kernel.org/r/20240219162917.2159736-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: 8250_pci1xxxx: Don't use "proxy" headers

Update header inclusions to follow IWYU (Include What You Use)
principle.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20240213193827.3207353-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

8250: microchip: Add 4 Mbps support in PCI1XXXX UART

The current clock input is set to 62.5 MHz for supporting fractional
divider, which enables generation of an acceptable baud rate from any
frequency. With the current clock input the baud rate range is limited
to 3.9 Mbps. Hence, the current range is extended to support 4 Mbps
with Burst mode operation. Divisor calculation for a given baud rate is
updated as the sampling rate is reduced from 16 to 8 for 4 Mbps.

Signed-off-by: Rengarajan S <rengarajan.s@microchip.com>
Link: https://lore.kernel.org/r/20240125100619.154873-1-rengarajan.s@microchip.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

8250: microchip: pci1xxxx: Add Burst mode transmission support in uart driver for reading from FIFO

pci1xxxx_handle_irq reads the burst status and checks if the FIFO
is empty and is ready to accept the incoming data. The handling is
done in pci1xxxx_tx_burst where each transaction processes data in
block of DWORDs, while any remaining bytes are processed individually,
one byte at a time.

Signed-off-by: Rengarajan S <rengarajan.s@microchip.com>
Link: https://lore.kernel.org/r/20240125100006.153342-1-rengarajan.s@microchip.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: 8250_pci1xxxx: partially revert off by one patch

I was reviewing this code again and I realized I made a mistake here.
It should have been > instead of >=. The subtract ensures that we
don't go out of bounds. My patch meant that we don't read the last
chunk of the buffer.

Fixes: 86ee55e9bc7f ("serial: 8250_pci1xxxx: fix off by one in pci1xxxx_process_read_data()")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://lore.kernel.org/r/bd6fb361-bbb9-427d-90e8-a5df4de76221@moroto.mountain
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: 8250_pci1xxxx: fix off by one in pci1xxxx_process_read_data()

These > comparisons should be >= to prevent writing one element beyond
the end of the rx_buff[] array. The rx_buff[] buffer has RX_BUF_SIZE
elements. Fix the buffer overflow.

Fixes: aba8290f368d ("8250: microchip: pci1xxxx: Add Burst mode reception support in uart driver for writing into FIFO")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://lore.kernel.org/r/ZZ7vIfj7Jgh-pJn8@moroto
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

8250: microchip: pci1xxxx: Add Burst mode reception support in uart driver for writing into FIFO

In PCI1XXXX C0 endpoint, support for Burst mode is added.
pci1xxxx_handle_irq checks the burst status and based on that
incoming characters are received in DWORDs, RX handling is done
in pci1xxxx_rx_burst. While reading the burst status the RX error
is checked and the corresponding error statistics are updated.

Signed-off-by: Rengarajan S <rengarajan.s@microchip.com>
Link: https://lore.kernel.org/r/20231215151123.41812-4-rengarajan.s@microchip.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

8250: microchip: pci1xxxx: Add Syslock support for reading UART system registers

Different Host drivers can attempt to access system registers
simultaneously from different memory spaces at the same time. The
syslock mechanism provides a safe option for reading UART system
registers and prevents conflicts by serializing access. Added
three padding bytes in the structure for memory alignment.

Signed-off-by: Rengarajan S <rengarajan.s@microchip.com>
Link: https://lore.kernel.org/r/20231215151123.41812-3-rengarajan.s@microchip.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

8250: microchip: pci1xxxx: Rearranging the structure declarations

Structure declarations in 8250_pci1xxxx.c have been moved above
the functions for code readability.

Signed-off-by: Rengarajan S <rengarajan.s@microchip.com>
Link: https://lore.kernel.org/r/20231215151123.41812-2-rengarajan.s@microchip.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: 8250_pci1xxxx: Annotate struct pci1xxxx_8250 with __counted_by

Prepare for the coming implementation by GCC and Clang of the __counted_by
attribute. Flexible array members annotated with __counted_by can have
their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
(for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
functions).

As found with Coccinelle[1], add __counted_by for struct pci1xxxx_8250.

[1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci

Cc: Kumaravel Thiagarajan <kumaravel.thiagarajan@microchip.com>
Cc: Tharun Kumar P <tharunkumar.pasumarthi@microchip.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jirislaby@kernel.org>
Cc: linux-serial@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20230922175242.work.442-kees@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: 8250_pci1xxxx: 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/20230914183831.587273-14-john.ogness@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: 8250_pci1xxxx: Add power management functions to quad-uart driver

pci1xxxx's quad-uart function has the capability to wake up UART
from suspend state. Enable wakeup before entering into suspend and
disable wakeup on resume.

Co-developed-by: Tharun Kumar P <tharunkumar.pasumarthi@microchip.com>
Signed-off-by: Tharun Kumar P <tharunkumar.pasumarthi@microchip.com>
Signed-off-by: Kumaravel Thiagarajan <kumaravel.thiagarajan@microchip.com>
Link: https://lore.kernel.org/r/20230207164814.3104605-5-kumaravel.thiagarajan@microchip.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: 8250_pci1xxxx: Add RS485 support to quad-uart driver

pci1xxxx uart supports RS485 mode of operation in the hardware with
auto-direction control with configurable delay for releasing RTS after
the transmission. This patch adds support for the RS485 mode.

Co-developed-by: Tharun Kumar P <tharunkumar.pasumarthi@microchip.com>
Signed-off-by: Tharun Kumar P <tharunkumar.pasumarthi@microchip.com>
Signed-off-by: Kumaravel Thiagarajan <kumaravel.thiagarajan@microchip.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20230207164814.3104605-4-kumaravel.thiagarajan@microchip.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: 8250_pci1xxxx: Add driver for quad-uart support

pci1xxxx is a PCIe switch with a multi-function endpoint on one of
its downstream ports. Quad-uart is one of the functions in the
multi-function endpoint. This driver loads for the quad-uart and
enumerates single or multiple instances of uart based on the PCIe
subsystem device ID.

Co-developed-by: Tharun Kumar P <tharunkumar.pasumarthi@microchip.com>
Signed-off-by: Tharun Kumar P <tharunkumar.pasumarthi@microchip.com>
Signed-off-by: Kumaravel Thiagarajan <kumaravel.thiagarajan@microchip.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20230207164814.3104605-3-kumaravel.thiagarajan@microchip.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>