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wdenk77f85582002-09-26 02:01:47 +00001/*
2 * (C) Copyright 2001
3 * Gerald Van Baren, Custom IDEAS, vanbaren@cideas.com.
4 *
5 * See file CREDITS for list of people who contributed to this
6 * project.
7 *
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License as
10 * published by the Free Software Foundation; either version 2 of
11 * the License, or (at your option) any later version.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
21 * MA 02111-1307 USA
22 */
23
24#ifndef _SPI_H_
25#define _SPI_H_
26
Guennadi Liakhovetski38254f42008-04-15 14:14:25 +020027/* SPI mode flags */
28#define SPI_CPHA 0x01 /* clock phase */
29#define SPI_CPOL 0x02 /* clock polarity */
30#define SPI_MODE_0 (0|0) /* (original MicroWire) */
31#define SPI_MODE_1 (0|SPI_CPHA)
32#define SPI_MODE_2 (SPI_CPOL|0)
33#define SPI_MODE_3 (SPI_CPOL|SPI_CPHA)
Haavard Skinnemoend255bb02008-05-16 11:10:31 +020034#define SPI_CS_HIGH 0x04 /* CS active high */
Guennadi Liakhovetski38254f42008-04-15 14:14:25 +020035#define SPI_LSB_FIRST 0x08 /* per-word bits-on-wire */
36#define SPI_3WIRE 0x10 /* SI/SO signals shared */
37#define SPI_LOOP 0x20 /* loopback mode */
38
Haavard Skinnemoend255bb02008-05-16 11:10:31 +020039/* SPI transfer flags */
40#define SPI_XFER_BEGIN 0x01 /* Assert CS before transfer */
41#define SPI_XFER_END 0x02 /* Deassert CS after transfer */
wdenk77f85582002-09-26 02:01:47 +000042
Haavard Skinnemoend255bb02008-05-16 11:10:31 +020043/*-----------------------------------------------------------------------
44 * Representation of a SPI slave, i.e. what we're communicating with.
45 *
46 * Drivers are expected to extend this with controller-specific data.
47 *
48 * bus: ID of the bus that the slave is attached to.
49 * cs: ID of the chip select connected to the slave.
50 */
51struct spi_slave {
52 unsigned int bus;
53 unsigned int cs;
54};
wdenk77f85582002-09-26 02:01:47 +000055
56/*-----------------------------------------------------------------------
57 * Initialization, must be called once on start up.
Haavard Skinnemoend255bb02008-05-16 11:10:31 +020058 *
59 * TODO: I don't think we really need this.
wdenk77f85582002-09-26 02:01:47 +000060 */
61void spi_init(void);
62
Haavard Skinnemoend255bb02008-05-16 11:10:31 +020063/*-----------------------------------------------------------------------
64 * Set up communications parameters for a SPI slave.
65 *
66 * This must be called once for each slave. Note that this function
67 * usually doesn't touch any actual hardware, it only initializes the
68 * contents of spi_slave so that the hardware can be easily
69 * initialized later.
70 *
71 * bus: Bus ID of the slave chip.
72 * cs: Chip select ID of the slave chip on the specified bus.
73 * max_hz: Maximum SCK rate in Hz.
74 * mode: Clock polarity, clock phase and other parameters.
75 *
76 * Returns: A spi_slave reference that can be used in subsequent SPI
77 * calls, or NULL if one or more of the parameters are not supported.
78 */
79struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
80 unsigned int max_hz, unsigned int mode);
81
82/*-----------------------------------------------------------------------
83 * Free any memory associated with a SPI slave.
84 *
85 * slave: The SPI slave
86 */
87void spi_free_slave(struct spi_slave *slave);
88
89/*-----------------------------------------------------------------------
90 * Claim the bus and prepare it for communication with a given slave.
91 *
92 * This must be called before doing any transfers with a SPI slave. It
93 * will enable and initialize any SPI hardware as necessary, and make
94 * sure that the SCK line is in the correct idle state. It is not
95 * allowed to claim the same bus for several slaves without releasing
96 * the bus in between.
97 *
98 * slave: The SPI slave
99 *
100 * Returns: 0 if the bus was claimed successfully, or a negative value
101 * if it wasn't.
102 */
103int spi_claim_bus(struct spi_slave *slave);
104
105/*-----------------------------------------------------------------------
106 * Release the SPI bus
107 *
108 * This must be called once for every call to spi_claim_bus() after
109 * all transfers have finished. It may disable any SPI hardware as
110 * appropriate.
111 *
112 * slave: The SPI slave
113 */
114void spi_release_bus(struct spi_slave *slave);
wdenk77f85582002-09-26 02:01:47 +0000115
116/*-----------------------------------------------------------------------
117 * SPI transfer
118 *
119 * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks
120 * "bitlen" bits in the SPI MISO port. That's just the way SPI works.
121 *
122 * The source of the outgoing bits is the "dout" parameter and the
123 * destination of the input bits is the "din" parameter. Note that "dout"
124 * and "din" can point to the same memory location, in which case the
125 * input data overwrites the output data (since both are buffered by
126 * temporary variables, this is OK).
127 *
wdenk77f85582002-09-26 02:01:47 +0000128 * spi_xfer() interface:
Haavard Skinnemoend255bb02008-05-16 11:10:31 +0200129 * slave: The SPI slave which will be sending/receiving the data.
130 * bitlen: How many bits to write and read.
131 * dout: Pointer to a string of bits to send out. The bits are
132 * held in a byte array and are sent MSB first.
133 * din: Pointer to a string of bits that will be filled in.
134 * flags: A bitwise combination of SPI_XFER_* flags.
wdenk77f85582002-09-26 02:01:47 +0000135 *
136 * Returns: 0 on success, not 0 on failure
137 */
Haavard Skinnemoend255bb02008-05-16 11:10:31 +0200138int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout,
139 void *din, unsigned long flags);
Guennadi Liakhovetski38254f42008-04-15 14:14:25 +0200140
Haavard Skinnemoend255bb02008-05-16 11:10:31 +0200141/*-----------------------------------------------------------------------
142 * Determine if a SPI chipselect is valid.
143 * This function is provided by the board if the low-level SPI driver
144 * needs it to determine if a given chipselect is actually valid.
145 *
146 * Returns: 1 if bus:cs identifies a valid chip on this board, 0
147 * otherwise.
148 */
149int spi_cs_is_valid(unsigned int bus, unsigned int cs);
150
151/*-----------------------------------------------------------------------
152 * Activate a SPI chipselect.
153 * This function is provided by the board code when using a driver
154 * that can't control its chipselects automatically (e.g.
155 * common/soft_spi.c). When called, it should activate the chip select
156 * to the device identified by "slave".
157 */
158void spi_cs_activate(struct spi_slave *slave);
159
160/*-----------------------------------------------------------------------
161 * Deactivate a SPI chipselect.
162 * This function is provided by the board code when using a driver
163 * that can't control its chipselects automatically (e.g.
164 * common/soft_spi.c). When called, it should deactivate the chip
165 * select to the device identified by "slave".
166 */
167void spi_cs_deactivate(struct spi_slave *slave);
168
169/*-----------------------------------------------------------------------
170 * Write 8 bits, then read 8 bits.
171 * slave: The SPI slave we're communicating with
172 * byte: Byte to be written
173 *
174 * Returns: The value that was read, or a negative value on error.
175 *
176 * TODO: This function probably shouldn't be inlined.
177 */
178static inline int spi_w8r8(struct spi_slave *slave, unsigned char byte)
179{
180 unsigned char dout[2];
181 unsigned char din[2];
182 int ret;
183
184 dout[0] = byte;
185 dout[1] = 0;
186
187 ret = spi_xfer(slave, 16, dout, din, SPI_XFER_BEGIN | SPI_XFER_END);
188 return ret < 0 ? ret : din[1];
189}
wdenk77f85582002-09-26 02:01:47 +0000190
191#endif /* _SPI_H_ */