c9277bf4d97358169bcb4ef119f621a43a391b10
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 */
24 #ifndef _SPI_H_
25 #define _SPI_H_
27 /* Controller-specific definitions: */
29 /* SPI mode flags */
30 #define SPI_CPHA 0x01 /* clock phase */
31 #define SPI_CPOL 0x02 /* clock polarity */
32 #define SPI_MODE_0 (0|0) /* (original MicroWire) */
33 #define SPI_MODE_1 (0|SPI_CPHA)
34 #define SPI_MODE_2 (SPI_CPOL|0)
35 #define SPI_MODE_3 (SPI_CPOL|SPI_CPHA)
36 #define SPI_CS_HIGH 0x04 /* CS active high */
37 #define SPI_LSB_FIRST 0x08 /* per-word bits-on-wire */
38 #define SPI_3WIRE 0x10 /* SI/SO signals shared */
39 #define SPI_LOOP 0x20 /* loopback mode */
40 #define SPI_SLAVE 0x40 /* slave mode */
41 #define SPI_PREAMBLE 0x80 /* Skip preamble bytes */
42 #define SPI_6WIRE 0x10 /* 4 data lines */
44 /* SPI transfer flags */
45 #define SPI_XFER_BEGIN 0x01 /* Assert CS before transfer */
46 #define SPI_XFER_END 0x02 /* Deassert CS after transfer */
48 /*-----------------------------------------------------------------------
49 * Representation of a SPI slave, i.e. what we're communicating with.
50 *
51 * Drivers are expected to extend this with controller-specific data.
52 *
53 * bus: ID of the bus that the slave is attached to.
54 * cs: ID of the chip select connected to the slave.
55 * max_write_size: If non-zero, the maximum number of bytes which can
56 * be written at once, excluding command bytes.
57 */
58 struct spi_slave {
59 unsigned int bus;
60 unsigned int cs;
61 unsigned int max_write_size;
62 bool quad_enable;
63 };
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);
72 /**
73 * spi_do_alloc_slave - Allocate a new SPI slave (internal)
74 *
75 * Allocate and zero all fields in the spi slave, and set the bus/chip
76 * select. Use the helper macro spi_alloc_slave() to call this.
77 *
78 * @offset: Offset of struct spi_slave within slave structure
79 * @size: Size of slave structure
80 * @bus: Bus ID of the slave chip.
81 * @cs: Chip select ID of the slave chip on the specified bus.
82 */
83 void *spi_do_alloc_slave(int offset, int size, unsigned int bus,
84 unsigned int cs);
86 /**
87 * spi_alloc_slave - Allocate a new SPI slave
88 *
89 * Allocate and zero all fields in the spi slave, and set the bus/chip
90 * select.
91 *
92 * @_struct: Name of structure to allocate (e.g. struct tegra_spi). This
93 * structure must contain a member 'struct spi_slave *slave'.
94 * @bus: Bus ID of the slave chip.
95 * @cs: Chip select ID of the slave chip on the specified bus.
96 */
97 #define spi_alloc_slave(_struct, bus, cs) \
98 spi_do_alloc_slave(offsetof(_struct, slave), \
99 sizeof(_struct), bus, cs)
101 /**
102 * spi_alloc_slave_base - Allocate a new SPI slave with no private data
103 *
104 * Allocate and zero all fields in the spi slave, and set the bus/chip
105 * select.
106 *
107 * @bus: Bus ID of the slave chip.
108 * @cs: Chip select ID of the slave chip on the specified bus.
109 */
110 #define spi_alloc_slave_base(bus, cs) \
111 spi_do_alloc_slave(0, sizeof(struct spi_slave), bus, cs)
113 /*-----------------------------------------------------------------------
114 * Set up communications parameters for a SPI slave.
115 *
116 * This must be called once for each slave. Note that this function
117 * usually doesn't touch any actual hardware, it only initializes the
118 * contents of spi_slave so that the hardware can be easily
119 * initialized later.
120 *
121 * bus: Bus ID of the slave chip.
122 * cs: Chip select ID of the slave chip on the specified bus.
123 * max_hz: Maximum SCK rate in Hz.
124 * mode: Clock polarity, clock phase and other parameters.
125 *
126 * Returns: A spi_slave reference that can be used in subsequent SPI
127 * calls, or NULL if one or more of the parameters are not supported.
128 */
129 struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
130 unsigned int max_hz, unsigned int mode);
132 /*-----------------------------------------------------------------------
133 * Free any memory associated with a SPI slave.
134 *
135 * slave: The SPI slave
136 */
137 void spi_free_slave(struct spi_slave *slave);
139 /*-----------------------------------------------------------------------
140 * Claim the bus and prepare it for communication with a given slave.
141 *
142 * This must be called before doing any transfers with a SPI slave. It
143 * will enable and initialize any SPI hardware as necessary, and make
144 * sure that the SCK line is in the correct idle state. It is not
145 * allowed to claim the same bus for several slaves without releasing
146 * the bus in between.
147 *
148 * slave: The SPI slave
149 *
150 * Returns: 0 if the bus was claimed successfully, or a negative value
151 * if it wasn't.
152 */
153 int spi_claim_bus(struct spi_slave *slave);
155 /*-----------------------------------------------------------------------
156 * Release the SPI bus
157 *
158 * This must be called once for every call to spi_claim_bus() after
159 * all transfers have finished. It may disable any SPI hardware as
160 * appropriate.
161 *
162 * slave: The SPI slave
163 */
164 void spi_release_bus(struct spi_slave *slave);
166 /*-----------------------------------------------------------------------
167 * SPI transfer
168 *
169 * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks
170 * "bitlen" bits in the SPI MISO port. That's just the way SPI works.
171 *
172 * The source of the outgoing bits is the "dout" parameter and the
173 * destination of the input bits is the "din" parameter. Note that "dout"
174 * and "din" can point to the same memory location, in which case the
175 * input data overwrites the output data (since both are buffered by
176 * temporary variables, this is OK).
177 *
178 * spi_xfer() interface:
179 * slave: The SPI slave which will be sending/receiving the data.
180 * bitlen: How many bits to write and read.
181 * dout: Pointer to a string of bits to send out. The bits are
182 * held in a byte array and are sent MSB first.
183 * din: Pointer to a string of bits that will be filled in.
184 * flags: A bitwise combination of SPI_XFER_* flags.
185 *
186 * Returns: 0 on success, not 0 on failure
187 */
188 int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout,
189 void *din, unsigned long flags);
191 /*-----------------------------------------------------------------------
192 * Determine if a SPI chipselect is valid.
193 * This function is provided by the board if the low-level SPI driver
194 * needs it to determine if a given chipselect is actually valid.
195 *
196 * Returns: 1 if bus:cs identifies a valid chip on this board, 0
197 * otherwise.
198 */
199 int spi_cs_is_valid(unsigned int bus, unsigned int cs);
201 /*-----------------------------------------------------------------------
202 * Activate a SPI chipselect.
203 * This function is provided by the board code when using a driver
204 * that can't control its chipselects automatically (e.g.
205 * common/soft_spi.c). When called, it should activate the chip select
206 * to the device identified by "slave".
207 */
208 void spi_cs_activate(struct spi_slave *slave);
210 /*-----------------------------------------------------------------------
211 * Deactivate a SPI chipselect.
212 * This function is provided by the board code when using a driver
213 * that can't control its chipselects automatically (e.g.
214 * common/soft_spi.c). When called, it should deactivate the chip
215 * select to the device identified by "slave".
216 */
217 void spi_cs_deactivate(struct spi_slave *slave);
219 /*-----------------------------------------------------------------------
220 * Set transfer speed.
221 * This sets a new speed to be applied for next spi_xfer().
222 * slave: The SPI slave
223 * hz: The transfer speed
224 */
225 void spi_set_speed(struct spi_slave *slave, uint hz);
227 /*-----------------------------------------------------------------------
228 * Write 8 bits, then read 8 bits.
229 * slave: The SPI slave we're communicating with
230 * byte: Byte to be written
231 *
232 * Returns: The value that was read, or a negative value on error.
233 *
234 * TODO: This function probably shouldn't be inlined.
235 */
236 static inline int spi_w8r8(struct spi_slave *slave, unsigned char byte)
237 {
238 unsigned char dout[2];
239 unsigned char din[2];
240 int ret;
242 dout[0] = byte;
243 dout[1] = 0;
245 ret = spi_xfer(slave, 16, dout, din, SPI_XFER_BEGIN | SPI_XFER_END);
246 return ret < 0 ? ret : din[1];
247 }
249 #endif /* _SPI_H_ */