dt-bindings: sdhci-sprd: Add bindings for the sdhci-sprd controller

This patch adds the device-tree binding documentation for Spreadtrum
SDHCI driver.

Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

diff --git a/Documentation/devicetree/bindings/mmc/sdhci-sprd.txt b/Documentation/devicetree/bindings/mmc/sdhci-sprd.txt
new file mode 100644 (file)
index 0000000..45c9978
--- /dev/null
+++ b/Documentation/devicetree/bindings/mmc/sdhci-sprd.txt
@@ -0,0 +1,41 @@
+* Spreadtrum SDHCI controller (sdhci-sprd)
+
+The Secure Digital (SD) Host controller on Spreadtrum SoCs provides an interface
+for MMC, SD and SDIO types of cards.
+
+This file documents differences between the core properties in mmc.txt
+and the properties used by the sdhci-sprd driver.
+
+Required properties:
+- compatible: Should contain "sprd,sdhci-r11".
+- reg: physical base address of the controller and length.
+- interrupts: Interrupts used by the SDHCI controller.
+- clocks: Should contain phandle for the clock feeding the SDHCI controller
+- clock-names: Should contain the following:
+       "sdio" - SDIO source clock (required)
+       "enable" - gate clock which used for enabling/disabling the device (required)
+
+Optional properties:
+- assigned-clocks: the same with "sdio" clock
+- assigned-clock-parents: the default parent of "sdio" clock
+
+Examples:
+
+sdio0: sdio@20600000 {
+       compatible  = "sprd,sdhci-r11";
+       reg = <0 0x20600000 0 0x1000>;
+       interrupts = <GIC_SPI 60 IRQ_TYPE_LEVEL_HIGH>;
+
+       clock-names = "sdio", "enable";
+       clocks = <&ap_clk CLK_EMMC_2X>,
+                <&apahb_gate CLK_EMMC_EB>;
+       assigned-clocks = <&ap_clk CLK_EMMC_2X>;
+       assigned-clock-parents = <&rpll CLK_RPLL_390M>;
+
+       bus-width = <8>;
+       non-removable;
+       no-sdio;
+       no-sd;
+       cap-mmc-hw-reset;
+       status = "okay";
+};