xref: /linux/Documentation/devicetree/bindings/mfd/aspeed-lpc.yaml (revision 55a42f78ffd386e01a5404419f8c5ded7db70a21) 
1# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
2# # Copyright (c) 2021 Aspeed Technology Inc.
3%YAML 1.2
4---
5$id: http://devicetree.org/schemas/mfd/aspeed-lpc.yaml#
6$schema: http://devicetree.org/meta-schemas/core.yaml#
7
8title: Aspeed Low Pin Count (LPC) Bus Controller
9
10maintainers:
11  - Andrew Jeffery <andrew@aj.id.au>
12  - Chia-Wei Wang <chiawei_wang@aspeedtech.com>
13
14description:
15  The LPC bus is a means to bridge a host CPU to a number of low-bandwidth
16  peripheral devices, replacing the use of the ISA bus in the age of PCI[0]. The
17  primary use case of the Aspeed LPC controller is as a slave on the bus
18  (typically in a Baseboard Management Controller SoC), but under certain
19  conditions it can also take the role of bus master.
20
21  The LPC controller is represented as a multi-function device to account for the
22  mix of functionality, which includes, but is not limited to
23
24  * An IPMI Block Transfer[2] Controller
25
26  * An LPC Host Interface Controller manages functions exposed to the host such
27    as LPC firmware hub cycles, configuration of the LPC-to-AHB mapping, UART
28    management and bus snoop configuration.
29
30  * A set of SuperIO[3] scratch registers enabling implementation of e.g. custom
31    hardware management protocols for handover between the host and baseboard
32    management controller.
33
34  Additionally the state of the LPC controller influences the pinmux
35  configuration, therefore the host portion of the controller is exposed as a
36  syscon as a means to arbitrate access.
37
38properties:
39  compatible:
40    items:
41      - enum:
42          - aspeed,ast2400-lpc-v2
43          - aspeed,ast2500-lpc-v2
44          - aspeed,ast2600-lpc-v2
45      - const: simple-mfd
46      - const: syscon
47
48  reg:
49    maxItems: 1
50
51  "#address-cells":
52    const: 1
53
54  "#size-cells":
55    const: 1
56
57  ranges: true
58
59patternProperties:
60  "^lpc-ctrl@[0-9a-f]+$":
61    type: object
62    additionalProperties: false
63
64    description: |
65      The LPC Host Interface Controller manages functions exposed to the host such as
66      LPC firmware hub cycles, configuration of the LPC-to-AHB mapping, UART management
67      and bus snoop configuration.
68
69    properties:
70      compatible:
71        items:
72          - enum:
73              - aspeed,ast2400-lpc-ctrl
74              - aspeed,ast2500-lpc-ctrl
75              - aspeed,ast2600-lpc-ctrl
76
77      reg:
78        maxItems: 1
79
80      clocks:
81        maxItems: 1
82
83      memory-region:
84        maxItems: 1
85        description: handle to memory reservation for the LPC to AHB mapping region
86
87      flash:
88        $ref: /schemas/types.yaml#/definitions/phandle
89        description: The SPI flash controller containing the flash to be exposed over the LPC to AHB mapping
90
91    required:
92      - compatible
93      - clocks
94
95  "^reset-controller@[0-9a-f]+$":
96    type: object
97    additionalProperties: false
98
99    description:
100      The UARTs present in the ASPEED SoC can have their resets tied to the reset
101      state of the LPC bus. Some systems may chose to modify this configuration
102
103    properties:
104      compatible:
105        items:
106          - enum:
107              - aspeed,ast2400-lpc-reset
108              - aspeed,ast2500-lpc-reset
109              - aspeed,ast2600-lpc-reset
110
111      reg:
112        maxItems: 1
113
114      '#reset-cells':
115        const: 1
116
117    required:
118      - compatible
119      - '#reset-cells'
120
121  "^lpc-snoop@[0-9a-f]+$":
122    type: object
123    additionalProperties: false
124
125    description:
126      The LPC snoop interface allows the BMC to listen on and record the data
127      bytes written by the Host to the targeted LPC I/O pots.
128
129    properties:
130      compatible:
131        items:
132          - enum:
133              - aspeed,ast2400-lpc-snoop
134              - aspeed,ast2500-lpc-snoop
135              - aspeed,ast2600-lpc-snoop
136
137      reg:
138        maxItems: 1
139
140      clocks:
141        maxItems: 1
142
143      interrupts:
144        maxItems: 1
145
146      snoop-ports:
147        $ref: /schemas/types.yaml#/definitions/uint32-array
148        description: The LPC I/O ports to snoop
149
150    required:
151      - compatible
152      - interrupts
153      - snoop-ports
154
155  "^uart-routing@[0-9a-f]+$":
156    $ref: /schemas/soc/aspeed/uart-routing.yaml#
157    description: The UART routing control under LPC register space
158
159required:
160  - compatible
161  - reg
162  - "#address-cells"
163  - "#size-cells"
164  - ranges
165
166additionalProperties:
167  type: object
168
169examples:
170  - |
171    #include <dt-bindings/interrupt-controller/arm-gic.h>
172    #include <dt-bindings/clock/ast2600-clock.h>
173
174    lpc: lpc@1e789000 {
175        compatible = "aspeed,ast2600-lpc-v2", "simple-mfd", "syscon";
176        reg = <0x1e789000 0x1000>;
177
178        #address-cells = <1>;
179        #size-cells = <1>;
180        ranges = <0x0 0x1e789000 0x1000>;
181
182        lpc_ctrl: lpc-ctrl@80 {
183            compatible = "aspeed,ast2600-lpc-ctrl";
184            reg = <0x80 0x80>;
185            clocks = <&syscon ASPEED_CLK_GATE_LCLK>;
186            memory-region = <&flash_memory>;
187            flash = <&spi>;
188        };
189
190        lpc_reset: reset-controller@98 {
191            compatible = "aspeed,ast2600-lpc-reset";
192            reg = <0x98 0x4>;
193            #reset-cells = <1>;
194        };
195
196        lpc_snoop: lpc-snoop@90 {
197            compatible = "aspeed,ast2600-lpc-snoop";
198            reg = <0x90 0x8>;
199            interrupts = <GIC_SPI 144 IRQ_TYPE_LEVEL_HIGH>;
200            snoop-ports = <0x80>;
201        };
202    };
203