diff options
| -rw-r--r-- | Documentation/acpi/enumeration.txt | 27 | ||||
| -rw-r--r-- | drivers/mfd/mfd-core.c | 40 | ||||
| -rw-r--r-- | include/linux/mfd/core.h | 3 |
3 files changed, 70 insertions, 0 deletions
diff --git a/Documentation/acpi/enumeration.txt b/Documentation/acpi/enumeration.txt index e182be5e3c83..b60d2ab69497 100644 --- a/Documentation/acpi/enumeration.txt +++ b/Documentation/acpi/enumeration.txt @@ -312,3 +312,30 @@ a code like this: There are also devm_* versions of these functions which release the descriptors once the device is released. + +MFD devices +~~~~~~~~~~~ +The MFD devices register their children as platform devices. For the child +devices there needs to be an ACPI handle that they can use to reference +parts of the ACPI namespace that relate to them. In the Linux MFD subsystem +we provide two ways: + + o The children share the parent ACPI handle. + o The MFD cell can specify the ACPI id of the device. + +For the first case, the MFD drivers do not need to do anything. The +resulting child platform device will have its ACPI_COMPANION() set to point +to the parent device. + +If the ACPI namespace has a device that we can match using an ACPI id, +the id should be set like: + + static struct mfd_cell my_subdevice_cell = { + .name = "my_subdevice", + /* set the resources relative to the parent */ + .acpi_pnpid = "XYZ0001", + }; + +The ACPI id "XYZ0001" is then used to lookup an ACPI device directly under +the MFD device and if found, that ACPI companion device is bound to the +resulting child platform device. diff --git a/drivers/mfd/mfd-core.c b/drivers/mfd/mfd-core.c index 5d0fbe1e097a..f3338fe9d069 100644 --- a/drivers/mfd/mfd-core.c +++ b/drivers/mfd/mfd-core.c @@ -78,6 +78,44 @@ static int mfd_platform_add_cell(struct platform_device *pdev, return 0; } +#if IS_ENABLED(CONFIG_ACPI) +static void mfd_acpi_add_device(const struct mfd_cell *cell, + struct platform_device *pdev) +{ + struct acpi_device *parent_adev; + struct acpi_device *adev; + + parent_adev = ACPI_COMPANION(pdev->dev.parent); + if (!parent_adev) + return; + + /* + * MFD child device gets its ACPI handle either from the ACPI + * device directly under the parent that matches the acpi_pnpid or + * it will use the parent handle if is no acpi_pnpid is given. + */ + adev = parent_adev; + if (cell->acpi_pnpid) { + struct acpi_device_id ids[2] = {}; + struct acpi_device *child_adev; + + strlcpy(ids[0].id, cell->acpi_pnpid, sizeof(ids[0].id)); + list_for_each_entry(child_adev, &parent_adev->children, node) + if (acpi_match_device_ids(child_adev, ids)) { + adev = child_adev; + break; + } + } + + ACPI_COMPANION_SET(&pdev->dev, adev); +} +#else +static inline void mfd_acpi_add_device(const struct mfd_cell *cell, + struct platform_device *pdev) +{ +} +#endif + static int mfd_add_device(struct device *parent, int id, const struct mfd_cell *cell, atomic_t *usage_count, struct resource *mem_base, @@ -119,6 +157,8 @@ static int mfd_add_device(struct device *parent, int id, } } + mfd_acpi_add_device(cell, pdev); + if (cell->pdata_size) { ret = platform_device_add_data(pdev, cell->platform_data, cell->pdata_size); diff --git a/include/linux/mfd/core.h b/include/linux/mfd/core.h index f543de91ce19..73e1709d4c09 100644 --- a/include/linux/mfd/core.h +++ b/include/linux/mfd/core.h @@ -44,6 +44,9 @@ struct mfd_cell { */ const char *of_compatible; + /* Matches ACPI PNP id, either _HID or _CID */ + const char *acpi_pnpid; + /* * These resources can be specified relative to the parent device. * For accessing hardware you should use resources from the platform dev |