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