[PATCH v1 1/2] dt-bindings: mmc: sdhci-of-aspeed: Add power-gpio and power-switch-gpio

[Steven Lee]

AST2600-A2 EVB provides the reference design for enabling SD bus power
and toggling SD bus signal voltage by GPIO pins.
Add the definition and example for power-gpio and power-switch-gpio
properties.

In the reference design, GPIOV0 of AST2600-A2 EVB is connected to power
load switch that providing 3.3v to SD1 bus vdd. GPIOV1 is connected to
a 1.8v and a 3.3v power load switch that providing signal voltage to
SD1 bus.
If GPIOV0 is active high, SD1 bus is enabled. Otherwise, SD1 bus is
disabled.
If GPIOV1 is active high, 3.3v power load switch is enabled, SD1 signal
voltage is 3.3v. Otherwise, 1.8v power load switch will be enabled, SD1
signal voltage becomes 1.8v.

AST2600-A2 EVB also support toggling signal voltage for SD2 bus.
The design is the same as SD1 bus. It uses GPIOV2 as power-gpio and GPIOV3
as power-switch-gpio.

Signed-off-by: Steven Lee <steven_lee at aspeedtech.com>
---
 .../devicetree/bindings/mmc/aspeed,sdhci.yaml | 25 +++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/Documentation/devicetree/bindings/mmc/aspeed,sdhci.yaml b/Documentation/devicetree/bindings/mmc/aspeed,sdhci.yaml
index 987b287f3bff..515a74614f3c 100644
--- a/Documentation/devicetree/bindings/mmc/aspeed,sdhci.yaml
+++ b/Documentation/devicetree/bindings/mmc/aspeed,sdhci.yaml
@@ -37,6 +37,14 @@ properties:
   clocks:
     maxItems: 1
     description: The SD/SDIO controller clock gate
+  power-gpio:
+    description:
+      The GPIO for enabling/disabling SD bus power.
+    maxItems: 1
+  power-switch-gpio:
+    description:
+      The GPIO for toggling the signal voltage between 3.3v and 1.8v.
+    maxItems: 1
 
 patternProperties:
   "^sdhci@[0-9a-f]+$":
@@ -61,6 +69,14 @@ patternProperties:
       sdhci,auto-cmd12:
         type: boolean
         description: Specifies that controller should use auto CMD12
+      power-gpio:
+        description:
+          The GPIO for enabling/disabling SD bus power.
+        maxItems: 1
+      power-switch-gpio:
+        description:
+          The GPIO for toggling the signal voltage between 3.3v and 1.8v.
+        maxItems: 1
     required:
       - compatible
       - reg
@@ -80,6 +96,7 @@ required:
 examples:
   - |
     #include <dt-bindings/clock/aspeed-clock.h>
+    #include <dt-bindings/gpio/aspeed-gpio.h>
     sdc at 1e740000 {
             compatible = "aspeed,ast2500-sd-controller";
             reg = <0x1e740000 0x100>;
@@ -94,6 +111,10 @@ examples:
                     interrupts = <26>;
                     sdhci,auto-cmd12;
                     clocks = <&syscon ASPEED_CLK_SDIO>;
+                    power-gpio = <&gpio0 ASPEED_GPIO(V, 0)
+                                     GPIO_ACTIVE_HIGH>;
+                    power-switch-gpio = <&gpio0 ASPEED_GPIO(V, 1)
+                                     GPIO_ACTIVE_HIGH>;
             };
 
             sdhci1: sdhci at 200 {
@@ -102,5 +123,9 @@ examples:
                     interrupts = <26>;
                     sdhci,auto-cmd12;
                     clocks = <&syscon ASPEED_CLK_SDIO>;
+                    power-gpio = <&gpio0 ASPEED_GPIO(V, 2)
+                                     GPIO_ACTIVE_HIGH>;
+                    power-switch-gpio = <&gpio0 ASPEED_GPIO(V, 3)
+                                     GPIO_ACTIVE_HIGH>;
             };
     };
-- 
2.17.1