SDIO / MMC device model (DM)

The MMC/SD core (dev_mmcsd_core.c, …) builds with **RT_USING_SDIO** alone. DM helpers are an extra layer: only when **RT_USING_DM** is on does **SConscript** add **dev_sdio_dm.c** (see **components/drivers/sdio/SConscript**). APIs live in **dev_sdio_dm.h**.

Feature	Kconfig (typical)	Source (only with `RT_USING_DM`)
Host naming, OFW parse	`RT_USING_DM` + `RT_USING_OFW` for parse	`dev_sdio_dm.c`
SDHCI stack	`RT_USING_DM` + `RT_USING_SDIO` + `RT_USING_SDHCI`	`dev_sdhci.c`, `dev_sdhci_dm.c`, `dev_sdhci_host.c`
`vmmc` / `vqmmc`	`RT_USING_DM` + `RT_USING_REGULATOR`	`dev_regulator.c`
SoC SDHCI / DW MMC hosts	`RT_USING_DM` + `RT_USING_SDIO`	`sdio/host/` (see `host/Kconfig`*)

Without **RT_USING_DM**, implement **struct rt_mmcsd_host_ops** yourself and use SDIO / MMC core; there is no in-tree **dev_sdhci_*** or **sdio_regulator_*** build.

Driver / BSP quick notes

Topic	Guidance
Parse before card activity	Call `sdio_ofw_parse` (when `RT_USING_OFW`) while filling `struct rt_mmcsd_host` and before the core starts enumeration—invalid `bus-width` yields `-RT_EIO`; handle in `probe` instead of at first transaction.
Stable host names	Prefer DTS `aliases { mmcN = &...; }` so `sdio_host_set_name` matches board wiring and userland scripts; purely software hosts still rely on `rt_ofw_get_alias_last_id("mmc")` to avoid colliding with aliased indices.
Supplies	`vmmc` / `vqmmc` need DM + regulator—see SDIO supplies (regulator) and Regulator.
SDHCI (DM only)	`RT_USING_SDHCI` is implemented only with DM. Platform drivers use `dev_sdhci_dm.c` (`rt_dm_dev_iomap`, `rt_dm_dev_get_irq`, `rt_sdhci_get_property`)—see SDHCI host controller.

Host naming: <tt>sdio_host_set_name</tt>

**sdio_host_set_name(host, out_devname)** fills **host->name** with a stable **sdu** string.

If **RT_USING_OFW** and **host->ofw_node** are set, it first tries **rt_ofw_get_alias_id(host->ofw_node, "mmc")** so names align with **aliases { mmc0 = &...; }** in DTS.
Otherwise it allocates a monotonic numeric id (atomically, seeded from **rt_ofw_get_alias_last_id("mmc")** when OFW is enabled so software-only hosts do not collide with aliased indices).

Optional **out_devname** receives a copy of the same string (up to **RT_NAME_MAX**).

Open Firmware: <tt>sdio_ofw_parse</tt>

When **RT_USING_OFW** is enabled, **sdio_ofw_parse(dev_np, host)** parses common MMC controller properties from **dev_np** into **struct rt_mmcsd_host**:

Property	Effect
`bus-width`	`1` / `4` / `8` → sets *`MMCSD_BUSWIDTH_` in `host->flags`; invalid values return `-RT_EIO`**.
`max-frequency`	`host->freq_max`.
`non-removable`	`MMCSD_SUP_NONREMOVABLE`.
`cap-sdio-irq`	`MMCSD_SUP_SDIO_IRQ`.
`cap-sd-highspeed` / `cap-mmc-highspeed`	`MMCSD_SUP_HIGHSPEED`.
*`mmc-ddr-`, `mmc-hs200-`, `mmc-hs400-`**	DDR / HS200 / HS400 capability flags.
*`sd-uhs-`**	UHS SDR/DDR capability flags.

It also assigns **host->ofw_node** if it was not already set (**host->ofw_node ? : dev_np**), and forces **MMCSD_MUTBLKWRITE** in **host->flags**.

Without **RT_USING_OFW**, **sdio_ofw_parse** is a stub that returns **RT_EOK** and does nothing.

Regulator hooks (DM + regulator)

**dev_regulator.c** is compiled only when **RT_USING_DM** and **RT_USING_REGULATOR** are both set (regulator framework itself depends on DM). See SDIO supplies (regulator) for **vmmc / vqmmc**.

SDHCI (DM + SDHCI)

**RT_USING_SDHCI** pulls in **dev_sdhci.c** only under **RT_USING_DM**. Platform probe uses **dev_sdhci_dm.c** (**rt_sdhci_pltfm_init**, **rt_dm_dev_iomap**, **rt_dm_dev_get_irq**, **rt_sdhci_get_property**). Details: SDHCI host controller.