1 /*
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
27 /* Controller-specific definitions: */
28
29 /* CONFIG_HARD_SPI triggers SPI bus initialization in PowerPC */
30 #ifdef CONFIG_MPC8XXX_SPI
31 # ifndef CONFIG_HARD_SPI
32 # define CONFIG_HARD_SPI
33 # endif
34 #endif
35
36 /* SPI mode flags */
37 #define SPI_CPHA 0x01 /* clock phase */
38 #define SPI_CPOL 0x02 /* clock polarity */
39 #define SPI_MODE_0 (0|0) /* (original MicroWire) */
40 #define SPI_MODE_1 (0|SPI_CPHA)
41 #define SPI_MODE_2 (SPI_CPOL|0)
42 #define SPI_MODE_3 (SPI_CPOL|SPI_CPHA)
43 #define SPI_CS_HIGH 0x04 /* CS active high */
44 #define SPI_LSB_FIRST 0x08 /* per-word bits-on-wire */
45 #define SPI_3WIRE 0x10 /* SI/SO signals shared */
46 #define SPI_LOOP 0x20 /* loopback mode */
47
48 /* SPI transfer flags */
49 #define SPI_XFER_BEGIN 0x01 /* Assert CS before transfer */
50 #define SPI_XFER_END 0x02 /* Deassert CS after transfer */
51
52 /*-----------------------------------------------------------------------
53 * Representation of a SPI slave, i.e. what we're communicating with.
54 *
55 * Drivers are expected to extend this with controller-specific data.
56 *
57 * bus: ID of the bus that the slave is attached to.
58 * cs: ID of the chip select connected to the slave.
59 */
60 struct spi_slave {
61 unsigned int bus;
62 unsigned int cs;
63 };
64
65 /*-----------------------------------------------------------------------
66 * Initialization, must be called once on start up.
67 *
68 * TODO: I don't think we really need this.
69 */
70 void spi_init(void);
71
72 /*-----------------------------------------------------------------------
73 * Set up communications parameters for a SPI slave.
74 *
75 * This must be called once for each slave. Note that this function
76 * usually doesn't touch any actual hardware, it only initializes the
77 * contents of spi_slave so that the hardware can be easily
78 * initialized later.
79 *
80 * bus: Bus ID of the slave chip.
81 * cs: Chip select ID of the slave chip on the specified bus.
82 * max_hz: Maximum SCK rate in Hz.
83 * mode: Clock polarity, clock phase and other parameters.
84 *
85 * Returns: A spi_slave reference that can be used in subsequent SPI
86 * calls, or NULL if one or more of the parameters are not supported.
87 */
88 struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
89 unsigned int max_hz, unsigned int mode);
90
91 /*-----------------------------------------------------------------------
92 * Free any memory associated with a SPI slave.
93 *
94 * slave: The SPI slave
95 */
96 void spi_free_slave(struct spi_slave *slave);
97
98 /*-----------------------------------------------------------------------
99 * Claim the bus and prepare it for communication with a given slave.
100 *
101 * This must be called before doing any transfers with a SPI slave. It
102 * will enable and initialize any SPI hardware as necessary, and make
103 * sure that the SCK line is in the correct idle state. It is not
104 * allowed to claim the same bus for several slaves without releasing
105 * the bus in between.
106 *
107 * slave: The SPI slave
108 *
109 * Returns: 0 if the bus was claimed successfully, or a negative value
110 * if it wasn't.
111 */
112 int spi_claim_bus(struct spi_slave *slave);
113
114 /*-----------------------------------------------------------------------
115 * Release the SPI bus
116 *
117 * This must be called once for every call to spi_claim_bus() after
118 * all transfers have finished. It may disable any SPI hardware as
119 * appropriate.
120 *
121 * slave: The SPI slave
122 */
123 void spi_release_bus(struct spi_slave *slave);
124
125 /*-----------------------------------------------------------------------
126 * SPI transfer
127 *
128 * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks
129 * "bitlen" bits in the SPI MISO port. That's just the way SPI works.
130 *
131 * The source of the outgoing bits is the "dout" parameter and the
132 * destination of the input bits is the "din" parameter. Note that "dout"
133 * and "din" can point to the same memory location, in which case the
134 * input data overwrites the output data (since both are buffered by
135 * temporary variables, this is OK).
136 *
137 * spi_xfer() interface:
138 * slave: The SPI slave which will be sending/receiving the data.
139 * bitlen: How many bits to write and read.
140 * dout: Pointer to a string of bits to send out. The bits are
141 * held in a byte array and are sent MSB first.
142 * din: Pointer to a string of bits that will be filled in.
143 * flags: A bitwise combination of SPI_XFER_* flags.
144 *
145 * Returns: 0 on success, not 0 on failure
146 */
147 int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout,
148 void *din, unsigned long flags);
149
150 /*-----------------------------------------------------------------------
151 * Determine if a SPI chipselect is valid.
152 * This function is provided by the board if the low-level SPI driver
153 * needs it to determine if a given chipselect is actually valid.
154 *
155 * Returns: 1 if bus:cs identifies a valid chip on this board, 0
156 * otherwise.
157 */
158 int spi_cs_is_valid(unsigned int bus, unsigned int cs);
159
160 /*-----------------------------------------------------------------------
161 * Activate 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 activate the chip select
165 * to the device identified by "slave".
166 */
167 void spi_cs_activate(struct spi_slave *slave);
168
169 /*-----------------------------------------------------------------------
170 * Deactivate a SPI chipselect.
171 * This function is provided by the board code when using a driver
172 * that can't control its chipselects automatically (e.g.
173 * common/soft_spi.c). When called, it should deactivate the chip
174 * select to the device identified by "slave".
175 */
176 void spi_cs_deactivate(struct spi_slave *slave);
177
178 /*-----------------------------------------------------------------------
179 * Write 8 bits, then read 8 bits.
180 * slave: The SPI slave we're communicating with
181 * byte: Byte to be written
182 *
183 * Returns: The value that was read, or a negative value on error.
184 *
185 * TODO: This function probably shouldn't be inlined.
186 */
spi_w8r8(struct spi_slave * slave,unsigned char byte)187 static inline int spi_w8r8(struct spi_slave *slave, unsigned char byte)
188 {
189 unsigned char dout[2];
190 unsigned char din[2];
191 int ret;
192
193 dout[0] = byte;
194 dout[1] = 0;
195
196 ret = spi_xfer(slave, 16, dout, din, SPI_XFER_BEGIN | SPI_XFER_END);
197 return ret < 0 ? ret : din[1];
198 }
199
200 #endif /* _SPI_H_ */
201