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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,rk3188-io-voltage-domain" for rk3188
35 - "rockchip,rk3288-io-voltage-domain" for rk3288
36 - "rockchip,rk3368-io-voltage-domain" for rk3368
37 - "rockchip,rk3368-pmu-io-voltage-domain" for rk3368 pmu-domains
38 - "rockchip,rk3399-io-voltage-domain" for rk3399
39 - "rockchip,rk3399-pmu-io-voltage-domain" for rk3399 pmu-domains
40
41Deprecated properties:
42- rockchip,grf: phandle to the syscon managing the "general register files"
43 Systems should move the io-domains to a sub-node of the grf simple-mfd.
44
45You specify supplies using the standard regulator bindings by including
46a phandle the relevant regulator. All specified supplies must be able
47to report their voltage. The IO Voltage Domain for any non-specified
48supplies will be not be touched.
49
50Possible supplies for rk3188:
51- ap0-supply: The supply connected to AP0_VCC.
52- ap1-supply: The supply connected to AP1_VCC.
53- cif-supply: The supply connected to CIF_VCC.
54- flash-supply: The supply connected to FLASH_VCC.
55- lcdc0-supply: The supply connected to LCD0_VCC.
56- lcdc1-supply: The supply connected to LCD1_VCC.
57- vccio0-supply: The supply connected to VCCIO0.
58- vccio1-supply: The supply connected to VCCIO1.
59 Sometimes also labeled VCCIO1 and VCCIO2.
60
61Possible supplies for rk3288:
62- audio-supply: The supply connected to APIO4_VDD.
63- bb-supply: The supply connected to APIO5_VDD.
64- dvp-supply: The supply connected to DVPIO_VDD.
65- flash0-supply: The supply connected to FLASH0_VDD. Typically for eMMC
66- flash1-supply: The supply connected to FLASH1_VDD. Also known as SDIO1.
67- gpio30-supply: The supply connected to APIO1_VDD.
68- gpio1830 The supply connected to APIO2_VDD.
69- lcdc-supply: The supply connected to LCDC_VDD.
70- sdcard-supply: The supply connected to SDMMC0_VDD.
71- wifi-supply: The supply connected to APIO3_VDD. Also known as SDIO0.
72
73Possible supplies for rk3368:
74- audio-supply: The supply connected to APIO3_VDD.
75- dvp-supply: The supply connected to DVPIO_VDD.
76- flash0-supply: The supply connected to FLASH0_VDD. Typically for eMMC
77- gpio30-supply: The supply connected to APIO1_VDD.
78- gpio1830 The supply connected to APIO4_VDD.
79- sdcard-supply: The supply connected to SDMMC0_VDD.
80- wifi-supply: The supply connected to APIO2_VDD. Also known as SDIO0.
81
82Possible supplies for rk3368 pmu-domains:
83- pmu-supply: The supply connected to PMUIO_VDD.
84- vop-supply: The supply connected to LCDC_VDD.
85
86Possible supplies for rk3399:
87- bt656-supply: The supply connected to APIO2_VDD.
88- audio-supply: The supply connected to APIO5_VDD.
89- sdmmc-supply: The supply connected to SDMMC0_VDD.
90- gpio1830 The supply connected to APIO4_VDD.
91
92Possible supplies for rk3399 pmu-domains:
93- pmu1830-supply:The supply connected to PMUIO2_VDD.
94
95Example:
96
97 io-domains {
98 compatible = "rockchip,rk3288-io-voltage-domain";
99 rockchip,grf = <&grf>;
100
101 audio-supply = <&vcc18_codec>;
102 bb-supply = <&vcc33_io>;
103 dvp-supply = <&vcc_18>;
104 flash0-supply = <&vcc18_flashio>;
105 gpio1830-supply = <&vcc33_io>;
106 gpio30-supply = <&vcc33_pmuio>;
107 lcdc-supply = <&vcc33_lcd>;
108 sdcard-supply = <&vccio_sd>;
109 wifi-supply = <&vcc18_wl>;
110 };