135 lines
4.7 KiB
Plaintext
135 lines
4.7 KiB
Plaintext
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* TI Highspeed MMC host controller for OMAP and 66AK2G family.
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The Highspeed MMC Host Controller on TI OMAP and 66AK2G family
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provides an interface for MMC, SD, and SDIO types of memory cards.
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This file documents differences between the core properties described
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by mmc.txt and the properties used by the omap_hsmmc driver.
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Required properties:
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--------------------
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- compatible:
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Should be "ti,omap2-hsmmc", for OMAP2 controllers
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Should be "ti,omap3-hsmmc", for OMAP3 controllers
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Should be "ti,omap3-pre-es3-hsmmc" for OMAP3 controllers pre ES3.0
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Should be "ti,omap4-hsmmc", for OMAP4 controllers
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Should be "ti,am33xx-hsmmc", for AM335x controllers
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Should be "ti,k2g-hsmmc", "ti,omap4-hsmmc" for 66AK2G controllers.
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SoC specific required properties:
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---------------------------------
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The following are mandatory properties for OMAPs, AM33xx and AM43xx SoCs only:
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- ti,hwmods: Must be "mmc<n>", n is controller instance starting 1.
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The following are mandatory properties for 66AK2G SoCs only:
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- power-domains:Should contain a phandle to a PM domain provider node
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and an args specifier containing the MMC device id
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value. This property is as per the binding,
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Documentation/devicetree/bindings/soc/ti/sci-pm-domain.yaml
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- clocks: Must contain an entry for each entry in clock-names. Should
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be defined as per the he appropriate clock bindings consumer
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usage in Documentation/devicetree/bindings/clock/ti,sci-clk.yaml
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- clock-names: Shall be "fck" for the functional clock,
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and "mmchsdb_fck" for the debounce clock.
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Optional properties:
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--------------------
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- ti,dual-volt: boolean, supports dual voltage cards
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- <supply-name>-supply: phandle to the regulator device tree node
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"supply-name" examples are "vmmc",
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"vmmc_aux"(deprecated)/"vqmmc" etc
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- ti,non-removable: non-removable slot (like eMMC)
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- ti,needs-special-reset: Requires a special softreset sequence
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- ti,needs-special-hs-handling: HSMMC IP needs special setting
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for handling High Speed
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- dmas: List of DMA specifiers with the controller specific
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format as described in the generic DMA client
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binding. A tx and rx specifier is required.
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- dma-names: List of DMA request names. These strings correspond
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1:1 with the DMA specifiers listed in dmas.
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The string naming is to be "rx" and "tx" for
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RX and TX DMA requests, respectively.
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Examples:
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[hwmod populated DMA resources]
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mmc1: mmc@4809c000 {
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compatible = "ti,omap4-hsmmc";
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reg = <0x4809c000 0x400>;
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ti,hwmods = "mmc1";
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ti,dual-volt;
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bus-width = <4>;
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vmmc-supply = <&vmmc>; /* phandle to regulator node */
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ti,non-removable;
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};
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[generic DMA request binding]
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mmc1: mmc@4809c000 {
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compatible = "ti,omap4-hsmmc";
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reg = <0x4809c000 0x400>;
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ti,hwmods = "mmc1";
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ti,dual-volt;
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bus-width = <4>;
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vmmc-supply = <&vmmc>; /* phandle to regulator node */
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ti,non-removable;
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dmas = <&edma 24
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&edma 25>;
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dma-names = "tx", "rx";
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};
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[workaround for missing swakeup on am33xx]
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This SOC is missing the swakeup line, it will not detect SDIO irq
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while in suspend.
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------
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| PRCM |
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------
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^ |
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swakeup | | fclk
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| v
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------ ------- -----
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| card | -- CIRQ --> | hsmmc | -- IRQ --> | CPU |
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------ ------- -----
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In suspend the fclk is off and the module is disfunctional. Even register reads
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will fail. A small logic in the host will request fclk restore, when an
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external event is detected. Once the clock is restored, the host detects the
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event normally. Since am33xx doesn't have this line it never wakes from
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suspend.
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The workaround is to reconfigure the dat1 line as a GPIO upon suspend. To make
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this work, we need to set the named pinctrl states "default" and "idle".
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Prepare idle to remux dat1 as a gpio, and default to remux it back as sdio
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dat1. The MMC driver will then toggle between idle and default state during
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runtime.
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In summary:
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1. select matching 'compatible' section, see example below.
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2. specify pinctrl states "default" and "idle", "sleep" is optional.
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3. specify the gpio irq used for detecting sdio irq in suspend
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If configuration is incomplete, a warning message is emitted "falling back to
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polling". Also check the "sdio irq mode" in /sys/kernel/debug/mmc0/regs. Mind
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not every application needs SDIO irq, e.g. MMC cards.
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mmc1: mmc@48060100 {
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compatible = "ti,am33xx-hsmmc";
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...
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pinctrl-names = "default", "idle", "sleep"
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pinctrl-0 = <&mmc1_pins>;
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pinctrl-1 = <&mmc1_idle>;
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pinctrl-2 = <&mmc1_sleep>;
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...
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interrupts-extended = <&intc 64 &gpio2 28 IRQ_TYPE_LEVEL_LOW>;
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};
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mmc1_idle : pinmux_cirq_pin {
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pinctrl-single,pins = <
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0x0f8 0x3f /* GPIO2_28 */
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>;
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};
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