platform/mellanox: mlxreg-lc: 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>
Link: https://lore.kernel.org/r/20230927081040.2198742-19-u.kleine-koenig@pengutronix.de
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

platform/mellanox: mlxreg-lc: Make error handling flow consistent

Use 'goto' statement in error flow of mlxreg_lc_event_handler() at all
places for consistency.

This follow-up patch implementing comments from
https://www.spinics.net/lists/platform-driver-x86/msg34587.html

Signed-off-by: Vadim Pasternak <vadimp@nvidia.com>
Link: https://lore.kernel.org/r/20220904141113.49048-1-vadimp@nvidia.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

platform/mellanox: Remove redundant 'NULL' check

Remove 'NULL' check for 'data->hpdev.client' in error flow of
mlxreg_lc_probe(). It cannot be 'NULL' at this point.

Fixes: b4b830a34d80 ("platform/mellanox: mlxreg-lc: Fix error flow and extend verbosity")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Vadim Pasternak <vadimp@nvidia.com>
Link: https://lore.kernel.org/r/20220823201937.46855-5-vadimp@nvidia.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

platform/mellanox: Remove unnecessary code

Remove redundant 'NULL' check for of if 'data->notifier'.

Replace 'return err' by 'return 0' in mlxreg_lc_probe().

Fixes: 62f9529b8d5c87b ("platform/mellanox: mlxreg-lc: Add initial support for Nvidia line card devices")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Vadim Pasternak <vadimp@nvidia.com>
Link: https://lore.kernel.org/r/20220823201937.46855-4-vadimp@nvidia.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

platform/mellanox: mlxreg-lc: Fix locking issue

Fix locking issues:
- mlxreg_lc_state_update() takes a lock when set or clear
"MLXREG_LC_POWERED".
- All the devices can be deleted before MLXREG_LC_POWERED flag is cleared.

To fix it:
- Add lock() / unlock() at the beginning / end of
mlxreg_lc_event_handler() and remove locking from
mlxreg_lc_power_on_off() and mlxreg_lc_enable_disable()
- Add locked version of mlxreg_lc_state_update() -
mlxreg_lc_state_update_locked() for using outside
mlxreg_lc_event_handler().

(2) Remove redundant NULL check for of if 'data->notifier'.

Fixes: 62f9529b8d5c87b ("platform/mellanox: mlxreg-lc: Add initial support for Nvidia line card devices")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Vadim Pasternak <vadimp@nvidia.com>
Link: https://lore.kernel.org/r/20220823201937.46855-3-vadimp@nvidia.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

platform/mellanox: mlxreg-lc: Fix coverity warning

Fix smatch warning:
drivers/platform/mellanox/mlxreg-lc.c:866 mlxreg_lc_probe() warn: passing zero to 'PTR_ERR'
by removing 'err = PTR_ERR(regmap)'.

Fixes: b4b830a34d80 ("platform/mellanox: mlxreg-lc: Fix error flow and extend verbosity")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Vadim Pasternak <vadimp@nvidia.com>
Link: https://lore.kernel.org/r/20220823201937.46855-2-vadimp@nvidia.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

platform/mellanox: Remove redundant 'NULL' check

Remove 'NULL' check for 'data->hpdev.client' in error flow of
mlxreg_lc_probe(). It cannot be 'NULL' at this point.

Fixes: b4b830a34d80 ("platform/mellanox: mlxreg-lc: Fix error flow and extend verbosity")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Vadim Pasternak <vadimp@nvidia.com>
Link: https://lore.kernel.org/r/20220823201937.46855-5-vadimp@nvidia.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

platform/mellanox: Remove unnecessary code

Remove redundant 'NULL' check for of if 'data->notifier'.

Replace 'return err' by 'return 0' in mlxreg_lc_probe().

Fixes: 62f9529b8d5c87b ("platform/mellanox: mlxreg-lc: Add initial support for Nvidia line card devices")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Vadim Pasternak <vadimp@nvidia.com>
Link: https://lore.kernel.org/r/20220823201937.46855-4-vadimp@nvidia.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

platform/mellanox: mlxreg-lc: Fix locking issue

Fix locking issues:
- mlxreg_lc_state_update() takes a lock when set or clear
"MLXREG_LC_POWERED".
- All the devices can be deleted before MLXREG_LC_POWERED flag is cleared.

To fix it:
- Add lock() / unlock() at the beginning / end of
mlxreg_lc_event_handler() and remove locking from
mlxreg_lc_power_on_off() and mlxreg_lc_enable_disable()
- Add locked version of mlxreg_lc_state_update() -
mlxreg_lc_state_update_locked() for using outside
mlxreg_lc_event_handler().

(2) Remove redundant NULL check for of if 'data->notifier'.

Fixes: 62f9529b8d5c87b ("platform/mellanox: mlxreg-lc: Add initial support for Nvidia line card devices")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Vadim Pasternak <vadimp@nvidia.com>
Link: https://lore.kernel.org/r/20220823201937.46855-3-vadimp@nvidia.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

platform/mellanox: mlxreg-lc: Fix coverity warning

Fix smatch warning:
drivers/platform/mellanox/mlxreg-lc.c:866 mlxreg_lc_probe() warn: passing zero to 'PTR_ERR'
by removing 'err = PTR_ERR(regmap)'.

Fixes: b4b830a34d80 ("platform/mellanox: mlxreg-lc: Fix error flow and extend verbosity")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Vadim Pasternak <vadimp@nvidia.com>
Link: https://lore.kernel.org/r/20220823201937.46855-2-vadimp@nvidia.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

platform/mellanox: mlxreg-lc: Fix error flow and extend verbosity

Fix error flow:
- Clean-up client object in case of probing failure.
- Prevent running remove routine in case of probing failure.
Probing and removing are invoked by hotplug events raised upon line
card insertion and removing. If probing procedure failed all data is
cleared and there is nothing to do in remove routine.

Fixes: 62f9529b8d5c ("platform/mellanox: mlxreg-lc: Add initial support for Nvidia line card devices")
Signed-off-by: Vadim Pasternak <vadimp@nvidia.com>
Link: https://lore.kernel.org/r/20220719153540.61304-1-vadimp@nvidia.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

platform/mellanox: mlxreg-lc: fix error code in mlxreg_lc_create_static_devices()

This code should be using PTR_ERR() instead of IS_ERR(). And because
it's using the wrong "dev->client" pointer, the IS_ERR() check will be
false, meaning the function returns success.

Fixes: 62f9529b8d5c ("platform/mellanox: mlxreg-lc: Add initial support for Nvidia line card devices")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Vadim Pasternak <vadimp@nvidia.com>
Link: https://lore.kernel.org/r/20211110074346.GB5176@kili
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

platform/mellanox: mlxreg-lc: Add initial support for Nvidia line card devices

Provide support for the Nvidia MSN4800-XX line cards for MSN4800
Ethernet modular switch system, providing a high performance switching
solution for Enterprise Data Centers (EDC) for building Ethernet based
clusters, High-Performance Computing (HPC) and embedded environments.
Initial version provides support for line card type MSN4800-C16. This
type of line card is equipped with:
- Lattice CPLD device, used for system and ports control.
- four Nvidia gearbox devices, used for port splitting.
- FPGA device, used for gearboxes management.
- 16x100G QSFP28 ports.
- hotpswap controllers, voltage regulators, analog-to-digital
convertors, nvram devices.
- status LED.

During initialization driver creates:
- line card's I2C tree through "i2c-mux-mlxcpd" driver.
- line card's LED objects through "leds-mlxreg" driver.
- line card's CPLD register space input / output "hwmon" attributes for
line control and monitoring through "mlxreg-io" driver. These
attributes provide CPLD and FPAG versioning, control for upgradable
components burning, NVRAM devices write protection, line card
revision, line card power consuming, line card reset cause
indication, etcetera.

Lattice CPLD device and nvram devices are feeding from auxiliary power
domain and accessible, when line card is powered off. These devices
are connected by line card driver probing routine, invoked after line
card security verification is done by hardware and event lc#n_verified
is received for line card located in slot #n.

Gearboxes, FPGA, hotpswap controllers, voltage regulators,
analog-to-digital convertors are feeding from main power domain. These
devices are connected after power good event "lc#n_powered" is received
for line card located in slot #n.

The driver 'mlxreg-lc' is driven by 'mlxreg-hotplug' driver following
relevant "hotplug" events.

Signed-off-by: Vadim Pasternak <vadimp@nvidia.com>
Reviewed-by: Michael Shych <michaelsh@nvidia.com>
Link: https://lore.kernel.org/r/20211002093238.3771419-8-vadimp@nvidia.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>