power: supply: surface_battery: replace deprecated strncpy with strscpy

strncpy() is deprecated for use on NUL-terminated destination strings
[1] and as such we should prefer more robust and less ambiguous string
interfaces.

We expect bat->name to be NUL-terminated based on its usage with
strcmp():

power_supply_core.c:
445: return strcmp(psy->desc->name, name) == 0;

... and also by the manual `... - 1` for the length argument of the
original strncpy() invocation.

Furthermore, no NUL-padding is needed as bat is zero-allocated before
calling spwr_battery_init():
826: bat = devm_kzalloc(&sdev->dev, sizeof(*bat), GFP_KERNEL);
827: if (!bat)
828: return -ENOMEM;
829:
830: spwr_battery_init(bat, sdev, p->registry, p->name);

... this means any further NUL-byte assignments (like the ones that
strncpy() does) are redundant.

Considering the above, a suitable replacement is `strscpy` [2] due to
the fact that it guarantees NUL-termination on the destination buffer
without unnecessarily NUL-padding.

Let's also opt to use the more idiomatic strscpy() usage of:
(dest, src, sizeof(dest)).

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Justin Stitt <justinstitt@google.com>
Link: https://lore.kernel.org/r/20231020-strncpy-drivers-power-supply-surface_battery-c-v2-1-29ed16b2caf1@google.com
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

platform/surface: aggregator: Enforce use of target-ID enum in device ID macros

Similar to the target category (TC), the target ID (TID) can be one
value out of a small number of choices, given in enum ssam_ssh_tid.

In the device ID macros, SSAM_SDEV() and SSAM_VDEV() we already use text
expansion to, both, remove some textual clutter for the target category
values and enforce that the value belongs to the known set. Now that we
know the names for the target IDs, use the same trick for them as well.

Also rename the SSAM_ANY_x macros to SSAM_SSH_x_ANY to better fit in.

Signed-off-by: Maximilian Luz <luzmaximilian@gmail.com>
Acked-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Link: https://lore.kernel.org/r/20221202223327.690880-9-luzmaximilian@gmail.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

power/supply: surface_battery: Use client device wrappers for notifier registration

Use newly introduced client device wrapper functions for notifier
registration and unregistration.

Signed-off-by: Maximilian Luz <luzmaximilian@gmail.com>
Acked-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Link: https://lore.kernel.org/r/20220527023447.2460025-7-luzmaximilian@gmail.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

power: supply: surface_battery: Fix battery event handling

The battery subsystem of the Surface Aggregator Module EC requires us to
register the battery notifier with instance ID 0. However, battery
events are actually sent with the instance ID corresponding to the
device, which is nonzero. Thus, the strict-matching approach doesn't
work here and will discard events that the driver is expected to handle.

To fix this we have to fall back on notifier matching by target-category
only and have to manually check the instance ID in the notifier
callback.

Fixes: 167f77f7d0b3 ("power: supply: Add battery driver for Surface Aggregator Module")
Signed-off-by: Maximilian Luz <luzmaximilian@gmail.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

power: supply: surface-battery: Make some symbols static

The sparse tool complains as follows:

drivers/power/supply/surface_battery.c:700:1: warning:
symbol 'dev_attr_alarm' was not declared. Should it be static?
drivers/power/supply/surface_battery.c:805:1: warning:
symbol 'surface_battery_pm_ops' was not declared. Should it be static?

This symbol is not used outside of surface_battery.c, so this
commit marks it static.

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Qiheng Lin <linqiheng@huawei.com>
Acked-by: Maximilian Luz <luzmaximilian@gmail.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

power: supply: Add battery driver for Surface Aggregator Module

On newer Microsoft Surface models (specifically 7th-generation, i.e.
Surface Pro 7, Surface Book 3, Surface Laptop 3, and Surface Laptop Go),
battery and AC status/information is no longer handled via standard ACPI
devices, but instead directly via the Surface System Aggregator Module
(SSAM), i.e. the embedded controller on those devices.

While on previous generation models, battery status is also handled via
SSAM, an ACPI shim was present to translate the standard ACPI battery
interface to SSAM requests. The SSAM interface itself, which is modeled
closely after the ACPI interface, has not changed.

This commit introduces a new SSAM client device driver to support
battery status/information via the aforementioned interface on said
Surface models. It is in parts based on the standard ACPI battery
driver.

Signed-off-by: Maximilian Luz <luzmaximilian@gmail.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>