3 * Gerald Van Baren, Custom IDEAS, vanbaren@cideas.com.
5 * See file CREDITS for list of people who contributed to this
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.
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.
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,
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)
34 #define SPI_CS_HIGH 0x04 /* CS active high */
35 #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 */
39 /* SPI transfer flags */
40 #define SPI_XFER_BEGIN 0x01 /* Assert CS before transfer */
41 #define SPI_XFER_END 0x02 /* Deassert CS after transfer */
43 /*-----------------------------------------------------------------------
44 * Representation of a SPI slave, i.e. what we're communicating with.
46 * Drivers are expected to extend this with controller-specific data.
48 * bus: ID of the bus that the slave is attached to.
49 * cs: ID of the chip select connected to the slave.
56 /*-----------------------------------------------------------------------
57 * Initialization, must be called once on start up.
59 * TODO: I don't think we really need this.
63 /*-----------------------------------------------------------------------
64 * Set up communications parameters for a SPI slave.
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
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.
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.
79 struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
80 unsigned int max_hz, unsigned int mode);
82 /*-----------------------------------------------------------------------
83 * Free any memory associated with a SPI slave.
85 * slave: The SPI slave
87 void spi_free_slave(struct spi_slave *slave);
89 /*-----------------------------------------------------------------------
90 * Claim the bus and prepare it for communication with a given slave.
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
98 * slave: The SPI slave
100 * Returns: 0 if the bus was claimed successfully, or a negative value
103 int spi_claim_bus(struct spi_slave *slave);
105 /*-----------------------------------------------------------------------
106 * Release the SPI bus
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
112 * slave: The SPI slave
114 void spi_release_bus(struct spi_slave *slave);
116 /*-----------------------------------------------------------------------
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.
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).
128 * spi_xfer() interface:
129 * 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.
136 * Returns: 0 on success, not 0 on failure
138 int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout,
139 void *din, unsigned long flags);
141 /*-----------------------------------------------------------------------
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.
146 * Returns: 1 if bus:cs identifies a valid chip on this board, 0
149 int spi_cs_is_valid(unsigned int bus, unsigned int cs);
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".
158 void spi_cs_activate(struct spi_slave *slave);
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".
167 void spi_cs_deactivate(struct spi_slave *slave);
169 /*-----------------------------------------------------------------------
170 * Write 8 bits, then read 8 bits.
171 * slave: The SPI slave we're communicating with
172 * byte: Byte to be written
174 * Returns: The value that was read, or a negative value on error.
176 * TODO: This function probably shouldn't be inlined.
178 static inline int spi_w8r8(struct spi_slave *slave, unsigned char byte)
180 unsigned char dout[2];
181 unsigned char din[2];
187 ret = spi_xfer(slave, 16, dout, din, SPI_XFER_BEGIN | SPI_XFER_END);
188 return ret < 0 ? ret : din[1];