4cbc6dbd52
On some boards (android tablets) different batches use different sdio wifi modules. This is not a problem since mmc/sdio is an enumerable bus, so we only need to describe and activate the mmc controller in dt and then the kernel will automatically load the right driver. Sometimes it is useful to specify certain ethernet properties for these "unknown" sdio devices, specifically we want the boot-loader to be able to set "local-mac-address" as some of these sdio wifi modules come without an eeprom / without a factory programmed mac address. Since the exact device is unknown (differs per batch) we cannot use a wifi-chip specific compatible, thus sometimes it is desirable to have a mmc function node, without having to make up an otherwise unused compatible for the node, so make the compatible property optional. Cc: Arnd Bergmann <arnd@arndb.de> Cc: Maxime Ripard <maxime.ripard@free-electrons.com> Signed-off-by: Hans de Goede <hdegoede@redhat.com> Acked-by: Rob Herring <robh@kernel.org> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
154 lines
6.2 KiB
Plaintext
154 lines
6.2 KiB
Plaintext
These properties are common to multiple MMC host controllers. Any host
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that requires the respective functionality should implement them using
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these definitions.
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Interpreted by the OF core:
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- reg: Registers location and length.
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- interrupts: Interrupts used by the MMC controller.
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Card detection:
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If no property below is supplied, host native card detect is used.
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Only one of the properties in this section should be supplied:
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- broken-cd: There is no card detection available; polling must be used.
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- cd-gpios: Specify GPIOs for card detection, see gpio binding
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- non-removable: non-removable slot (like eMMC); assume always present.
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Optional properties:
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- bus-width: Number of data lines, can be <1>, <4>, or <8>. The default
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will be <1> if the property is absent.
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- wp-gpios: Specify GPIOs for write protection, see gpio binding
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- cd-inverted: when present, polarity on the CD line is inverted. See the note
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below for the case, when a GPIO is used for the CD line
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- wp-inverted: when present, polarity on the WP line is inverted. See the note
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below for the case, when a GPIO is used for the WP line
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- disable-wp: When set no physical WP line is present. This property should
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only be specified when the controller has a dedicated write-protect
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detection logic. If a GPIO is always used for the write-protect detection
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logic it is sufficient to not specify wp-gpios property in the absence of a WP
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line.
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- max-frequency: maximum operating clock frequency
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- no-1-8-v: when present, denotes that 1.8v card voltage is not supported on
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this system, even if the controller claims it is.
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- cap-sd-highspeed: SD high-speed timing is supported
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- cap-mmc-highspeed: MMC high-speed timing is supported
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- sd-uhs-sdr12: SD UHS SDR12 speed is supported
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- sd-uhs-sdr25: SD UHS SDR25 speed is supported
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- sd-uhs-sdr50: SD UHS SDR50 speed is supported
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- sd-uhs-sdr104: SD UHS SDR104 speed is supported
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- sd-uhs-ddr50: SD UHS DDR50 speed is supported
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- cap-power-off-card: powering off the card is safe
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- cap-mmc-hw-reset: eMMC hardware reset is supported
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- cap-sdio-irq: enable SDIO IRQ signalling on this interface
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- full-pwr-cycle: full power cycle of the card is supported
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- mmc-ddr-1_8v: eMMC high-speed DDR mode(1.8V I/O) is supported
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- mmc-ddr-1_2v: eMMC high-speed DDR mode(1.2V I/O) is supported
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- mmc-hs200-1_8v: eMMC HS200 mode(1.8V I/O) is supported
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- mmc-hs200-1_2v: eMMC HS200 mode(1.2V I/O) is supported
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- mmc-hs400-1_8v: eMMC HS400 mode(1.8V I/O) is supported
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- mmc-hs400-1_2v: eMMC HS400 mode(1.2V I/O) is supported
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- mmc-hs400-enhanced-strobe: eMMC HS400 enhanced strobe mode is supported
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- dsr: Value the card's (optional) Driver Stage Register (DSR) should be
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programmed with. Valid range: [0 .. 0xffff].
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- no-sdio: controller is limited to send sdio cmd during initialization
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- no-sd: controller is limited to send sd cmd during initialization
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- no-mmc: controller is limited to send mmc cmd during initialization
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*NOTE* on CD and WP polarity. To use common for all SD/MMC host controllers line
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polarity properties, we have to fix the meaning of the "normal" and "inverted"
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line levels. We choose to follow the SDHCI standard, which specifies both those
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lines as "active low." Therefore, using the "cd-inverted" property means, that
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the CD line is active high, i.e. it is high, when a card is inserted. Similar
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logic applies to the "wp-inverted" property.
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CD and WP lines can be implemented on the hardware in one of two ways: as GPIOs,
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specified in cd-gpios and wp-gpios properties, or as dedicated pins. Polarity of
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dedicated pins can be specified, using *-inverted properties. GPIO polarity can
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also be specified using the OF_GPIO_ACTIVE_LOW flag. This creates an ambiguity
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in the latter case. We choose to use the XOR logic for GPIO CD and WP lines.
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This means, the two properties are "superimposed," for example leaving the
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OF_GPIO_ACTIVE_LOW flag clear and specifying the respective *-inverted
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property results in a double-inversion and actually means the "normal" line
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polarity is in effect.
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Optional SDIO properties:
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- keep-power-in-suspend: Preserves card power during a suspend/resume cycle
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- wakeup-source: Enables wake up of host system on SDIO IRQ assertion
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(Legacy property supported: "enable-sdio-wakeup")
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MMC power sequences:
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--------------------
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System on chip designs may specify a specific MMC power sequence. To
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successfully detect an (e)MMC/SD/SDIO card, that power sequence must be
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maintained while initializing the card.
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Optional property:
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- mmc-pwrseq: phandle to the MMC power sequence node. See "mmc-pwrseq-*"
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for documentation of MMC power sequence bindings.
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Use of Function subnodes
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------------------------
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On embedded systems the cards connected to a host may need additional
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properties. These can be specified in subnodes to the host controller node.
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The subnodes are identified by the standard 'reg' property.
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Which information exactly can be specified depends on the bindings for the
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SDIO function driver for the subnode, as specified by the compatible string.
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Required host node properties when using function subnodes:
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- #address-cells: should be one. The cell is the slot id.
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- #size-cells: should be zero.
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Required function subnode properties:
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- reg: Must contain the SDIO function number of the function this subnode
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describes. A value of 0 denotes the memory SD function, values from
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1 to 7 denote the SDIO functions.
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Optional function subnode properties:
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- compatible: name of SDIO function following generic names recommended practice
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Examples
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--------
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Basic example:
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sdhci@ab000000 {
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compatible = "sdhci";
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reg = <0xab000000 0x200>;
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interrupts = <23>;
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bus-width = <4>;
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cd-gpios = <&gpio 69 0>;
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cd-inverted;
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wp-gpios = <&gpio 70 0>;
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max-frequency = <50000000>;
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keep-power-in-suspend;
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wakeup-source;
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mmc-pwrseq = <&sdhci0_pwrseq>
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}
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Example with sdio function subnode:
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mmc3: mmc@01c12000 {
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#address-cells = <1>;
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#size-cells = <0>;
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pinctrl-names = "default";
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pinctrl-0 = <&mmc3_pins_a>;
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vmmc-supply = <®_vmmc3>;
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bus-width = <4>;
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non-removable;
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mmc-pwrseq = <&sdhci0_pwrseq>
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status = "okay";
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brcmf: bcrmf@1 {
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reg = <1>;
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compatible = "brcm,bcm43xx-fmac";
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interrupt-parent = <&pio>;
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interrupts = <10 8>; /* PH10 / EINT10 */
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interrupt-names = "host-wake";
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};
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};
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