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77f85581 WD |
1 | /* |
2 | * (C) Copyright 2001 | |
3 | * Gerald Van Baren, Custom IDEAS, vanbaren@cideas.com. | |
4 | * | |
1a459660 | 5 | * SPDX-License-Identifier: GPL-2.0+ |
77f85581 WD |
6 | */ |
7 | ||
8 | #ifndef _SPI_H_ | |
9 | #define _SPI_H_ | |
10 | ||
f8cc312b BW |
11 | /* Controller-specific definitions: */ |
12 | ||
38254f45 GL |
13 | /* SPI mode flags */ |
14 | #define SPI_CPHA 0x01 /* clock phase */ | |
15 | #define SPI_CPOL 0x02 /* clock polarity */ | |
16 | #define SPI_MODE_0 (0|0) /* (original MicroWire) */ | |
17 | #define SPI_MODE_1 (0|SPI_CPHA) | |
18 | #define SPI_MODE_2 (SPI_CPOL|0) | |
19 | #define SPI_MODE_3 (SPI_CPOL|SPI_CPHA) | |
d255bb0e | 20 | #define SPI_CS_HIGH 0x04 /* CS active high */ |
38254f45 GL |
21 | #define SPI_LSB_FIRST 0x08 /* per-word bits-on-wire */ |
22 | #define SPI_3WIRE 0x10 /* SI/SO signals shared */ | |
23 | #define SPI_LOOP 0x20 /* loopback mode */ | |
bb786b84 RS |
24 | #define SPI_SLAVE 0x40 /* slave mode */ |
25 | #define SPI_PREAMBLE 0x80 /* Skip preamble bytes */ | |
38254f45 | 26 | |
d255bb0e HS |
27 | /* SPI transfer flags */ |
28 | #define SPI_XFER_BEGIN 0x01 /* Assert CS before transfer */ | |
29 | #define SPI_XFER_END 0x02 /* Deassert CS after transfer */ | |
77f85581 | 30 | |
bb786b84 RS |
31 | /* Header byte that marks the start of the message */ |
32 | #define SPI_PREAMBLE_END_BYTE 0xec | |
33 | ||
d255bb0e HS |
34 | /*----------------------------------------------------------------------- |
35 | * Representation of a SPI slave, i.e. what we're communicating with. | |
36 | * | |
37 | * Drivers are expected to extend this with controller-specific data. | |
38 | * | |
39 | * bus: ID of the bus that the slave is attached to. | |
40 | * cs: ID of the chip select connected to the slave. | |
0c456cee SG |
41 | * max_write_size: If non-zero, the maximum number of bytes which can |
42 | * be written at once, excluding command bytes. | |
d255bb0e HS |
43 | */ |
44 | struct spi_slave { | |
45 | unsigned int bus; | |
46 | unsigned int cs; | |
0c456cee | 47 | unsigned int max_write_size; |
d255bb0e | 48 | }; |
77f85581 WD |
49 | |
50 | /*----------------------------------------------------------------------- | |
51 | * Initialization, must be called once on start up. | |
d255bb0e HS |
52 | * |
53 | * TODO: I don't think we really need this. | |
77f85581 WD |
54 | */ |
55 | void spi_init(void); | |
56 | ||
ba6c3ce9 SG |
57 | /** |
58 | * spi_do_alloc_slave - Allocate a new SPI slave (internal) | |
59 | * | |
60 | * Allocate and zero all fields in the spi slave, and set the bus/chip | |
61 | * select. Use the helper macro spi_alloc_slave() to call this. | |
62 | * | |
63 | * @offset: Offset of struct spi_slave within slave structure | |
64 | * @size: Size of slave structure | |
65 | * @bus: Bus ID of the slave chip. | |
66 | * @cs: Chip select ID of the slave chip on the specified bus. | |
67 | */ | |
68 | void *spi_do_alloc_slave(int offset, int size, unsigned int bus, | |
69 | unsigned int cs); | |
70 | ||
71 | /** | |
72 | * spi_alloc_slave - Allocate a new SPI slave | |
73 | * | |
74 | * Allocate and zero all fields in the spi slave, and set the bus/chip | |
75 | * select. | |
76 | * | |
77 | * @_struct: Name of structure to allocate (e.g. struct tegra_spi). This | |
78 | * structure must contain a member 'struct spi_slave *slave'. | |
79 | * @bus: Bus ID of the slave chip. | |
80 | * @cs: Chip select ID of the slave chip on the specified bus. | |
81 | */ | |
82 | #define spi_alloc_slave(_struct, bus, cs) \ | |
83 | spi_do_alloc_slave(offsetof(_struct, slave), \ | |
84 | sizeof(_struct), bus, cs) | |
85 | ||
86 | /** | |
87 | * spi_alloc_slave_base - Allocate a new SPI slave with no private data | |
88 | * | |
89 | * Allocate and zero all fields in the spi slave, and set the bus/chip | |
90 | * select. | |
91 | * | |
92 | * @bus: Bus ID of the slave chip. | |
93 | * @cs: Chip select ID of the slave chip on the specified bus. | |
94 | */ | |
95 | #define spi_alloc_slave_base(bus, cs) \ | |
96 | spi_do_alloc_slave(0, sizeof(struct spi_slave), bus, cs) | |
97 | ||
d255bb0e HS |
98 | /*----------------------------------------------------------------------- |
99 | * Set up communications parameters for a SPI slave. | |
100 | * | |
101 | * This must be called once for each slave. Note that this function | |
102 | * usually doesn't touch any actual hardware, it only initializes the | |
103 | * contents of spi_slave so that the hardware can be easily | |
104 | * initialized later. | |
105 | * | |
106 | * bus: Bus ID of the slave chip. | |
107 | * cs: Chip select ID of the slave chip on the specified bus. | |
108 | * max_hz: Maximum SCK rate in Hz. | |
109 | * mode: Clock polarity, clock phase and other parameters. | |
110 | * | |
111 | * Returns: A spi_slave reference that can be used in subsequent SPI | |
112 | * calls, or NULL if one or more of the parameters are not supported. | |
113 | */ | |
114 | struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs, | |
115 | unsigned int max_hz, unsigned int mode); | |
116 | ||
117 | /*----------------------------------------------------------------------- | |
118 | * Free any memory associated with a SPI slave. | |
119 | * | |
120 | * slave: The SPI slave | |
121 | */ | |
122 | void spi_free_slave(struct spi_slave *slave); | |
123 | ||
124 | /*----------------------------------------------------------------------- | |
125 | * Claim the bus and prepare it for communication with a given slave. | |
126 | * | |
127 | * This must be called before doing any transfers with a SPI slave. It | |
128 | * will enable and initialize any SPI hardware as necessary, and make | |
129 | * sure that the SCK line is in the correct idle state. It is not | |
130 | * allowed to claim the same bus for several slaves without releasing | |
131 | * the bus in between. | |
132 | * | |
133 | * slave: The SPI slave | |
134 | * | |
135 | * Returns: 0 if the bus was claimed successfully, or a negative value | |
136 | * if it wasn't. | |
137 | */ | |
138 | int spi_claim_bus(struct spi_slave *slave); | |
139 | ||
140 | /*----------------------------------------------------------------------- | |
141 | * Release the SPI bus | |
142 | * | |
143 | * This must be called once for every call to spi_claim_bus() after | |
144 | * all transfers have finished. It may disable any SPI hardware as | |
145 | * appropriate. | |
146 | * | |
147 | * slave: The SPI slave | |
148 | */ | |
149 | void spi_release_bus(struct spi_slave *slave); | |
77f85581 WD |
150 | |
151 | /*----------------------------------------------------------------------- | |
152 | * SPI transfer | |
153 | * | |
154 | * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks | |
155 | * "bitlen" bits in the SPI MISO port. That's just the way SPI works. | |
156 | * | |
157 | * The source of the outgoing bits is the "dout" parameter and the | |
158 | * destination of the input bits is the "din" parameter. Note that "dout" | |
159 | * and "din" can point to the same memory location, in which case the | |
160 | * input data overwrites the output data (since both are buffered by | |
161 | * temporary variables, this is OK). | |
162 | * | |
77f85581 | 163 | * spi_xfer() interface: |
d255bb0e HS |
164 | * slave: The SPI slave which will be sending/receiving the data. |
165 | * bitlen: How many bits to write and read. | |
166 | * dout: Pointer to a string of bits to send out. The bits are | |
167 | * held in a byte array and are sent MSB first. | |
168 | * din: Pointer to a string of bits that will be filled in. | |
169 | * flags: A bitwise combination of SPI_XFER_* flags. | |
77f85581 WD |
170 | * |
171 | * Returns: 0 on success, not 0 on failure | |
172 | */ | |
d255bb0e HS |
173 | int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout, |
174 | void *din, unsigned long flags); | |
175 | ||
176 | /*----------------------------------------------------------------------- | |
177 | * Determine if a SPI chipselect is valid. | |
178 | * This function is provided by the board if the low-level SPI driver | |
179 | * needs it to determine if a given chipselect is actually valid. | |
180 | * | |
181 | * Returns: 1 if bus:cs identifies a valid chip on this board, 0 | |
182 | * otherwise. | |
183 | */ | |
184 | int spi_cs_is_valid(unsigned int bus, unsigned int cs); | |
185 | ||
186 | /*----------------------------------------------------------------------- | |
187 | * Activate a SPI chipselect. | |
188 | * This function is provided by the board code when using a driver | |
189 | * that can't control its chipselects automatically (e.g. | |
190 | * common/soft_spi.c). When called, it should activate the chip select | |
191 | * to the device identified by "slave". | |
192 | */ | |
193 | void spi_cs_activate(struct spi_slave *slave); | |
194 | ||
195 | /*----------------------------------------------------------------------- | |
196 | * Deactivate a SPI chipselect. | |
197 | * This function is provided by the board code when using a driver | |
198 | * that can't control its chipselects automatically (e.g. | |
199 | * common/soft_spi.c). When called, it should deactivate the chip | |
200 | * select to the device identified by "slave". | |
201 | */ | |
202 | void spi_cs_deactivate(struct spi_slave *slave); | |
203 | ||
fa1423e7 TC |
204 | /*----------------------------------------------------------------------- |
205 | * Set transfer speed. | |
206 | * This sets a new speed to be applied for next spi_xfer(). | |
207 | * slave: The SPI slave | |
208 | * hz: The transfer speed | |
209 | */ | |
210 | void spi_set_speed(struct spi_slave *slave, uint hz); | |
211 | ||
d255bb0e HS |
212 | /*----------------------------------------------------------------------- |
213 | * Write 8 bits, then read 8 bits. | |
214 | * slave: The SPI slave we're communicating with | |
215 | * byte: Byte to be written | |
216 | * | |
217 | * Returns: The value that was read, or a negative value on error. | |
218 | * | |
219 | * TODO: This function probably shouldn't be inlined. | |
220 | */ | |
221 | static inline int spi_w8r8(struct spi_slave *slave, unsigned char byte) | |
222 | { | |
223 | unsigned char dout[2]; | |
224 | unsigned char din[2]; | |
225 | int ret; | |
226 | ||
227 | dout[0] = byte; | |
228 | dout[1] = 0; | |
38254f45 | 229 | |
d255bb0e HS |
230 | ret = spi_xfer(slave, 16, dout, din, SPI_XFER_BEGIN | SPI_XFER_END); |
231 | return ret < 0 ? ret : din[1]; | |
232 | } | |
77f85581 | 233 | |
f3424c55 HT |
234 | /** |
235 | * Set up a SPI slave for a particular device tree node | |
236 | * | |
237 | * This calls spi_setup_slave() with the correct bus number. Call | |
238 | * spi_free_slave() to free it later. | |
239 | * | |
240 | * @param blob Device tree blob | |
241 | * @param node SPI peripheral node to use | |
242 | * @param cs Chip select to use | |
243 | * @param max_hz Maximum SCK rate in Hz (0 for default) | |
244 | * @param mode Clock polarity, clock phase and other parameters | |
245 | * @return pointer to new spi_slave structure | |
246 | */ | |
247 | struct spi_slave *spi_setup_slave_fdt(const void *blob, int node, | |
248 | unsigned int cs, unsigned int max_hz, unsigned int mode); | |
249 | ||
77f85581 | 250 | #endif /* _SPI_H_ */ |