Implement the core infrastructure to allow MMC bus types to handle
REGULATOR_EVENT_UNDER_VOLTAGE events from power regulators. This is
primarily aimed at allowing devices like eMMC to perform an emergency
shutdown to prevent data corruption when a power failure is imminent.
This patch introduces:
- A new 'handle_undervoltage' function pointer to 'struct mmc_bus_ops'.
Bus drivers (e.g., for eMMC) can implement this to define their
emergency procedures.
- A workqueue ('uv_work') in 'struct mmc_supply' to handle the event
asynchronously in a high-priority context.
- A new function 'mmc_handle_undervoltage()' which is called from the
workqueue. It stops the host queue to prevent races with card removal,
checks for the bus op, and invokes the handler.
- Functions to register and unregister the regulator notifier, intended
to be called by bus drivers like 'mmc_attach_mmc' when a compatible
card is detected.
The notifier is only registered for the main vmmc supply, as
undervoltage handling for vqmmc or vqmmc2 is not required at this
time.
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Link: https://lore.kernel.org/r/20250821130751.2089587-2-o.rempel@pengutronix.de
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
To allow an additional external regulator to be controlled by an mmc host
driver, let's add support for a vqmmc2 regulator to the mmc core.
For an SD UHS-II interface the vqmmc2 regulator may correspond to the so
called vdd2 supply, as described by the SD spec. Initially, only 1.8V is
needed, hence limit the new helper function, mmc_regulator_set_vqmmc2() to
this too.
Note that, to allow for flexibility mmc host drivers need to manage the
enable/disable of the vqmmc2 regulator themselves, while the regulator is
looked up through the common mmc_regulator_get_supply().
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://lore.kernel.org/r/20240913102836.6144-5-victorshihgli@gmail.com
Remainder of the kerneldoc descriptions look present and correct.
Fixes the following W=1 kernel build warnings:
drivers/mmc/core/regulator.c:178: warning: Function parameter or member 'mmc' not described in 'mmc_regulator_set_vqmmc'
drivers/mmc/core/regulator.c:178: warning: Function parameter or member 'ios' not described in 'mmc_regulator_set_vqmmc'
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20200701124702.908713-4-lee.jones@linaro.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
The only left user of mmc_regulator_get_ocrmask() is the mmc core itself.
Therefore, let's drop the export and turn it into static.
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
The mmc regulator helper functions, are placed in the extensive core.c
file. In a step towards trying to create a better structure of files,
avoiding too many lines of code per file, let's move these helpers to a new
file, regulator.c.
Moreover, this within this context it makes sense to also drop the export
of mmc_vddrange_to_ocrmask(), but instead let's make it internal to the mmc
core.
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
