1Rockchip SRAM for IO Voltage Domains:
2-------------------------------------
3
4IO domain voltages on some Rockchip SoCs are variable but need to be
5kept in sync between the regulators and the SoC using a special
6register.
7
8A specific example using rk3288:
9- If the regulator hooked up to a pin like SDMMC0_VDD is 3.3V then
10  bit 7 of GRF_IO_VSEL needs to be 0.  If the regulator hooked up to
11  that same pin is 1.8V then bit 7 of GRF_IO_VSEL needs to be 1.
12
13Said another way, this driver simply handles keeping bits in the SoC's
14general register file (GRF) in sync with the actual value of a voltage
15hooked up to the pins.
16
17Note that this driver specifically doesn't include:
18- any logic for deciding what voltage we should set regulators to
19- any logic for deciding whether regulators (or internal SoC blocks)
20  should have power or not have power
21
22If there were some other software that had the smarts of making
23decisions about regulators, it would work in conjunction with this
24driver.  When that other software adjusted a regulator's voltage then
25this driver would handle telling the SoC about it.  A good example is
26vqmmc for SD.  In that case the dw_mmc driver simply is told about a
27regulator.  It changes the regulator between 3.3V and 1.8V at the
28right time.  This driver notices the change and makes sure that the
29SoC is on the same page.
30
31
32Required properties:
33- compatible: should be one of:
34  - "rockchip,px30-io-voltage-domain" for px30
35  - "rockchip,px30-pmu-io-voltage-domain" for px30 pmu-domains
36  - "rockchip,rk3188-io-voltage-domain" for rk3188
37  - "rockchip,rk3228-io-voltage-domain" for rk3228
38  - "rockchip,rk3288-io-voltage-domain" for rk3288
39  - "rockchip,rk3328-io-voltage-domain" for rk3328
40  - "rockchip,rk3368-io-voltage-domain" for rk3368
41  - "rockchip,rk3368-pmu-io-voltage-domain" for rk3368 pmu-domains
42  - "rockchip,rk3399-io-voltage-domain" for rk3399
43  - "rockchip,rk3399-pmu-io-voltage-domain" for rk3399 pmu-domains
44  - "rockchip,rv1108-io-voltage-domain" for rv1108
45  - "rockchip,rv1108-pmu-io-voltage-domain" for rv1108 pmu-domains
46
47Deprecated properties:
48- rockchip,grf: phandle to the syscon managing the "general register files"
49    Systems should move the io-domains to a sub-node of the grf simple-mfd.
50
51You specify supplies using the standard regulator bindings by including
52a phandle the relevant regulator.  All specified supplies must be able
53to report their voltage.  The IO Voltage Domain for any non-specified
54supplies will be not be touched.
55
56Possible supplies for PX30:
57- vccio6-supply: The supply connected to VCCIO6.
58- vccio1-supply: The supply connected to VCCIO1.
59- vccio2-supply: The supply connected to VCCIO2.
60- vccio3-supply: The supply connected to VCCIO3.
61- vccio4-supply: The supply connected to VCCIO4.
62- vccio5-supply: The supply connected to VCCIO5.
63- vccio-oscgpi-supply: The supply connected to VCCIO_OSCGPI.
64
65Possible supplies for PX30 pmu-domains:
66- pmuio1-supply: The supply connected to PMUIO1.
67- pmuio2-supply: The supply connected to PMUIO2.
68
69Possible supplies for rk3188:
70- ap0-supply:    The supply connected to AP0_VCC.
71- ap1-supply:    The supply connected to AP1_VCC.
72- cif-supply:    The supply connected to CIF_VCC.
73- flash-supply:  The supply connected to FLASH_VCC.
74- lcdc0-supply:  The supply connected to LCD0_VCC.
75- lcdc1-supply:  The supply connected to LCD1_VCC.
76- vccio0-supply: The supply connected to VCCIO0.
77- vccio1-supply: The supply connected to VCCIO1.
78                 Sometimes also labeled VCCIO1 and VCCIO2.
79
80Possible supplies for rk3228:
81- vccio1-supply: The supply connected to VCCIO1.
82- vccio2-supply: The supply connected to VCCIO2.
83- vccio3-supply: The supply connected to VCCIO3.
84- vccio4-supply: The supply connected to VCCIO4.
85
86Possible supplies for rk3288:
87- audio-supply:  The supply connected to APIO4_VDD.
88- bb-supply:     The supply connected to APIO5_VDD.
89- dvp-supply:    The supply connected to DVPIO_VDD.
90- flash0-supply: The supply connected to FLASH0_VDD.  Typically for eMMC
91- flash1-supply: The supply connected to FLASH1_VDD.  Also known as SDIO1.
92- gpio30-supply: The supply connected to APIO1_VDD.
93- gpio1830       The supply connected to APIO2_VDD.
94- lcdc-supply:   The supply connected to LCDC_VDD.
95- sdcard-supply: The supply connected to SDMMC0_VDD.
96- wifi-supply:   The supply connected to APIO3_VDD.  Also known as SDIO0.
97
98Possible supplies for rk3368:
99- audio-supply:  The supply connected to APIO3_VDD.
100- dvp-supply:    The supply connected to DVPIO_VDD.
101- flash0-supply: The supply connected to FLASH0_VDD.  Typically for eMMC
102- gpio30-supply: The supply connected to APIO1_VDD.
103- gpio1830       The supply connected to APIO4_VDD.
104- sdcard-supply: The supply connected to SDMMC0_VDD.
105- wifi-supply:   The supply connected to APIO2_VDD.  Also known as SDIO0.
106
107Possible supplies for rk3368 pmu-domains:
108- pmu-supply:    The supply connected to PMUIO_VDD.
109- vop-supply:    The supply connected to LCDC_VDD.
110
111Possible supplies for rk3399:
112- bt656-supply:  The supply connected to APIO2_VDD.
113- audio-supply:  The supply connected to APIO5_VDD.
114- sdmmc-supply:  The supply connected to SDMMC0_VDD.
115- gpio1830       The supply connected to APIO4_VDD.
116
117Possible supplies for rk3399 pmu-domains:
118- pmu1830-supply:The supply connected to PMUIO2_VDD.
119
120Example:
121
122	io-domains {
123		compatible = "rockchip,rk3288-io-voltage-domain";
124		rockchip,grf = <&grf>;
125
126		audio-supply = <&vcc18_codec>;
127		bb-supply = <&vcc33_io>;
128		dvp-supply = <&vcc_18>;
129		flash0-supply = <&vcc18_flashio>;
130		gpio1830-supply = <&vcc33_io>;
131		gpio30-supply = <&vcc33_pmuio>;
132		lcdc-supply = <&vcc33_lcd>;
133		sdcard-supply = <&vccio_sd>;
134		wifi-supply = <&vcc18_wl>;
135	};
136