serial: mctrl_gpio: split disable_ms into sync and no_sync APIs

In the Linux kernel, the following vulnerability has been resolved:

serial: mctrl_gpio: split disable_ms into sync and no_sync APIs

The following splat has been observed on a SAMA5D27 platform using

atmel_serial:

BUG: sleeping function called from invalid context at kernel/irq/manage.c:738

in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 27, name: kworker/u5:0

preempt_count: 1, expected: 0

INFO: lockdep is turned off.

irq event stamp: 0

hardirqs last enabled at (0): [<00000000>] 0x0

hardirqs last disabled at (0): [<c01588f0>] copy_process+0x1c4c/0x7bec

softirqs last enabled at (0): [<c0158944>] copy_process+0x1ca0/0x7bec

softirqs last disabled at (0): [<00000000>] 0x0

CPU: 0 UID: 0 PID: 27 Comm: kworker/u5:0 Not tainted 6.13.0-rc7+ #74

Hardware name: Atmel SAMA5

Workqueue: hci0 hci_power_on [bluetooth]

Call trace:

unwind_backtrace from show_stack+0x18/0x1c

show_stack from dump_stack_lvl+0x44/0x70

dump_stack_lvl from __might_resched+0x38c/0x598

__might_resched from disable_irq+0x1c/0x48

disable_irq from mctrl_gpio_disable_ms+0x74/0xc0

mctrl_gpio_disable_ms from atmel_disable_ms.part.0+0x80/0x1f4

atmel_disable_ms.part.0 from atmel_set_termios+0x764/0x11e8

atmel_set_termios from uart_change_line_settings+0x15c/0x994

uart_change_line_settings from uart_set_termios+0x2b0/0x668

uart_set_termios from tty_set_termios+0x600/0x8ec

tty_set_termios from ttyport_set_flow_control+0x188/0x1e0

ttyport_set_flow_control from wilc_setup+0xd0/0x524 [hci_wilc]

wilc_setup [hci_wilc] from hci_dev_open_sync+0x330/0x203c [bluetooth]

hci_dev_open_sync [bluetooth] from hci_dev_do_open+0x40/0xb0 [bluetooth]

hci_dev_do_open [bluetooth] from hci_power_on+0x12c/0x664 [bluetooth]

hci_power_on [bluetooth] from process_one_work+0x998/0x1a38

process_one_work from worker_thread+0x6e0/0xfb4

worker_thread from kthread+0x3d4/0x484

kthread from ret_from_fork+0x14/0x28

This warning is emitted when trying to toggle, at the highest level,

some flow control (with serdev_device_set_flow_control) in a device

driver. At the lowest level, the atmel_serial driver is using

serial_mctrl_gpio lib to enable/disable the corresponding IRQs

accordingly. The warning emitted by CONFIG_DEBUG_ATOMIC_SLEEP is due to

disable_irq (called in mctrl_gpio_disable_ms) being possibly called in

some atomic context (some tty drivers perform modem lines configuration

in regions protected by port lock).

Split mctrl_gpio_disable_ms into two differents APIs, a non-blocking one

and a blocking one. Replace mctrl_gpio_disable_ms calls with the

relevant version depending on whether the call is protected by some port

lock.