xref: /freebsd/sys/contrib/device-tree/Bindings/mfd/aspeed-lpc.yaml (revision 2a58b312b62f908ec92311d1bd8536dbaeb8e55b) 
1# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
2# # Copyright (c) 2021 Aspeed Tehchnology 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 enableing 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      interrupts:
141        maxItems: 1
142
143      snoop-ports:
144        $ref: /schemas/types.yaml#/definitions/uint32-array
145        description: The LPC I/O ports to snoop
146
147    required:
148      - compatible
149      - interrupts
150      - snoop-ports
151
152  "^uart-routing@[0-9a-f]+$":
153    $ref: /schemas/soc/aspeed/uart-routing.yaml#
154    description: The UART routing control under LPC register space
155
156required:
157  - compatible
158  - reg
159  - "#address-cells"
160  - "#size-cells"
161  - ranges
162
163additionalProperties:
164  type: object
165
166examples:
167  - |
168    #include <dt-bindings/interrupt-controller/arm-gic.h>
169    #include <dt-bindings/clock/ast2600-clock.h>
170
171    lpc: lpc@1e789000 {
172        compatible = "aspeed,ast2600-lpc-v2", "simple-mfd", "syscon";
173        reg = <0x1e789000 0x1000>;
174
175        #address-cells = <1>;
176        #size-cells = <1>;
177        ranges = <0x0 0x1e789000 0x1000>;
178
179        lpc_ctrl: lpc-ctrl@80 {
180            compatible = "aspeed,ast2600-lpc-ctrl";
181            reg = <0x80 0x80>;
182            clocks = <&syscon ASPEED_CLK_GATE_LCLK>;
183            memory-region = <&flash_memory>;
184            flash = <&spi>;
185        };
186
187        lpc_reset: reset-controller@98 {
188            compatible = "aspeed,ast2600-lpc-reset";
189            reg = <0x98 0x4>;
190            #reset-cells = <1>;
191        };
192
193        lpc_snoop: lpc-snoop@90 {
194            compatible = "aspeed,ast2600-lpc-snoop";
195            reg = <0x90 0x8>;
196            interrupts = <GIC_SPI 144 IRQ_TYPE_LEVEL_HIGH>;
197            snoop-ports = <0x80>;
198        };
199    };
200