power: supply: surface-charger: 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 ac->name to be NUL-terminated based on its usage with format
strings:

surface_charger.c:
190: ac->psy_desc.name = ac->name;

...

power_supply_core.c:
174: dev_dbg(&psy->dev, "%s: Found supply : %s\n",
175: psy->desc->name, epsy->desc->name);

Moreover, NUL-padding is not required as ac is already zero-allocated
before being passed to spwr_ac_init():

surface_charger.c:
240: ac = devm_kzalloc(&sdev->dev, sizeof(*ac), GFP_KERNEL);
241: if (!ac)
242: return -ENOMEM;
243:
244: spwr_ac_init(ac, sdev, p->registry, p->name);

... this means any future 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 for 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_charger-c-v1-1-93ddbf668e10@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_charger: 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/20220527023447.2460025-6-luzmaximilian@gmail.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

power: supply: surface-charger: Fix type of integer variable

The ac->state field is __le32, not u32. So change the variable we're
temporarily storing it in to __le32 as well.

Reported-by: kernel test robot <lkp@intel.com>
Fixes: e61ffb344591 ("power: supply: Add AC 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-charger: Make symbol 'surface_ac_pm_ops' static

The sparse tool complains as follows:

drivers/power/supply/surface_charger.c:229:1: warning:
symbol 'surface_ac_pm_ops' was not declared. Should it be static?

This symbol is not used outside of surface_charger.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 AC 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, AC status is also handled via SSAM,
an ACPI shim was present to translate the standard ACPI AC 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 AC
status/information via the aforementioned interface on said Surface
models.

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