reset: hisilicon: document hisi-hi6220 reset controllers bindings

Add DT bindings documentation for hi6220 SoC reset controller.
Signed-off-by: Chen Feng <puck.chen@hisilicon.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/reset/hisilicon,hi6220-reset.txt

+Hisilicon System Reset Controller
+======================================
+
+Please also refer to reset.txt in this directory for common reset
+controller binding usage.
+
+The reset controller registers are part of the system-ctl block on
+hi6220 SoC.
+
+Required properties:
+- compatible: may be "hisilicon,hi6220-sysctrl"
+- reg: should be register base and length as documented in the
+  datasheet
+- #reset-cells: 1, see below
+
+Example:
+sys_ctrl: sys_ctrl@f7030000 {
+	compatible = "hisilicon,hi6220-sysctrl", "syscon";
+	reg = <0x0 0xf7030000 0x0 0x2000>;
+	#clock-cells = <1>;
+	#reset-cells = <1>;
+};
+
+Specifying reset lines connected to IP modules
+==============================================
+example:
+
+        uart1: serial@..... {
+                ...
+                resets = <&sys_ctrl PERIPH_RSTEN3_UART1>;
+                ...
+        };
+
+The index could be found in <dt-bindings/reset/hisi,hi6220-resets.h>.

include/dt-bindings/reset/hisi,hi6220-resets.h

+/**
+ * This header provides index for the reset controller
+ * based on hi6220 SoC.
+ */
+#ifndef _DT_BINDINGS_RESET_CONTROLLER_HI6220
+#define _DT_BINDINGS_RESET_CONTROLLER_HI6220
+
+#define PERIPH_RSTDIS0_MMC0             0x000
+#define PERIPH_RSTDIS0_MMC1             0x001
+#define PERIPH_RSTDIS0_MMC2             0x002
+#define PERIPH_RSTDIS0_NANDC            0x003
+#define PERIPH_RSTDIS0_USBOTG_BUS       0x004
+#define PERIPH_RSTDIS0_POR_PICOPHY      0x005
+#define PERIPH_RSTDIS0_USBOTG           0x006
+#define PERIPH_RSTDIS0_USBOTG_32K       0x007
+#define PERIPH_RSTDIS1_HIFI             0x100
+#define PERIPH_RSTDIS1_DIGACODEC        0x105
+#define PERIPH_RSTEN2_IPF               0x200
+#define PERIPH_RSTEN2_SOCP              0x201
+#define PERIPH_RSTEN2_DMAC              0x202
+#define PERIPH_RSTEN2_SECENG            0x203
+#define PERIPH_RSTEN2_ABB               0x204
+#define PERIPH_RSTEN2_HPM0              0x205
+#define PERIPH_RSTEN2_HPM1              0x206
+#define PERIPH_RSTEN2_HPM2              0x207
+#define PERIPH_RSTEN2_HPM3              0x208
+#define PERIPH_RSTEN3_CSSYS             0x300
+#define PERIPH_RSTEN3_I2C0              0x301
+#define PERIPH_RSTEN3_I2C1              0x302
+#define PERIPH_RSTEN3_I2C2              0x303
+#define PERIPH_RSTEN3_I2C3              0x304
+#define PERIPH_RSTEN3_UART1             0x305
+#define PERIPH_RSTEN3_UART2             0x306
+#define PERIPH_RSTEN3_UART3             0x307
+#define PERIPH_RSTEN3_UART4             0x308
+#define PERIPH_RSTEN3_SSP               0x309
+#define PERIPH_RSTEN3_PWM               0x30a
+#define PERIPH_RSTEN3_BLPWM             0x30b
+#define PERIPH_RSTEN3_TSENSOR           0x30c
+#define PERIPH_RSTEN3_DAPB              0x312
+#define PERIPH_RSTEN3_HKADC             0x313
+#define PERIPH_RSTEN3_CODEC_SSI         0x314
+#define PERIPH_RSTEN3_PMUSSI1           0x316
+#define PERIPH_RSTEN8_RS0               0x400
+#define PERIPH_RSTEN8_RS2               0x401
+#define PERIPH_RSTEN8_RS3               0x402
+#define PERIPH_RSTEN8_MS0               0x403
+#define PERIPH_RSTEN8_MS2               0x405
+#define PERIPH_RSTEN8_XG2RAM0           0x406
+#define PERIPH_RSTEN8_X2SRAM_TZMA       0x407
+#define PERIPH_RSTEN8_SRAM              0x408
+#define PERIPH_RSTEN8_HARQ              0x40a
+#define PERIPH_RSTEN8_DDRC              0x40c
+#define PERIPH_RSTEN8_DDRC_APB          0x40d
+#define PERIPH_RSTEN8_DDRPACK_APB       0x40e
+#define PERIPH_RSTEN8_DDRT              0x411
+#define PERIPH_RSDIST9_CARM_DAP         0x500
+#define PERIPH_RSDIST9_CARM_ATB         0x501
+#define PERIPH_RSDIST9_CARM_LBUS        0x502
+#define PERIPH_RSDIST9_CARM_POR         0x503
+#define PERIPH_RSDIST9_CARM_CORE        0x504
+#define PERIPH_RSDIST9_CARM_DBG         0x505
+#define PERIPH_RSDIST9_CARM_L2          0x506
+#define PERIPH_RSDIST9_CARM_SOCDBG      0x507
+#define PERIPH_RSDIST9_CARM_ETM         0x508
+
+#endif /*_DT_BINDINGS_RESET_CONTROLLER_HI6220*/