iPXE
spi_bit.c
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1 /*
2  * Copyright (C) 2006 Michael Brown <mbrown@fensystems.co.uk>.
3  *
4  * This program is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU General Public License as
6  * published by the Free Software Foundation; either version 2 of the
7  * License, or any later version.
8  *
9  * This program is distributed in the hope that it will be useful, but
10  * WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12  * General Public License for more details.
13  *
14  * You should have received a copy of the GNU General Public License
15  * along with this program; if not, write to the Free Software
16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
17  * 02110-1301, USA.
18  *
19  * You can also choose to distribute this program under the terms of
20  * the Unmodified Binary Distribution Licence (as given in the file
21  * COPYING.UBDL), provided that you have satisfied its requirements.
22  */
23 
24 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
25 
26 #include <stddef.h>
27 #include <stdint.h>
28 #include <string.h>
29 #include <byteswap.h>
30 #include <errno.h>
31 #include <assert.h>
32 #include <unistd.h>
33 #include <ipxe/bitbash.h>
34 #include <ipxe/spi_bit.h>
35 
36 /** @file
37  *
38  * SPI bit-bashing interface
39  *
40  */
41 
42 /** Delay between SCLK changes and around SS changes */
43 static void spi_bit_delay ( void ) {
45 }
46 
47 /** Chip select line will be asserted */
48 #define SELECT_SLAVE 0
49 
50 /** Chip select line will be deasserted */
51 #define DESELECT_SLAVE SPI_MODE_SSPOL
52 
53 /**
54  * Select/deselect slave
55  *
56  * @v spibit SPI bit-bashing interface
57  * @v slave Slave number
58  * @v state Slave select state
59  *
60  * @c state must be @c SELECT_SLAVE or @c DESELECT_SLAVE.
61  */
62 static void spi_bit_set_slave_select ( struct spi_bit_basher *spibit,
63  unsigned int slave,
64  unsigned int state ) {
65  struct bit_basher *basher = &spibit->basher;
66 
67  state ^= ( spibit->bus.mode & SPI_MODE_SSPOL );
68  DBGC2 ( spibit, "SPIBIT %p setting slave %d select %s\n",
69  spibit, slave, ( state ? "high" : "low" ) );
70 
71  spi_bit_delay();
72  write_bit ( basher, SPI_BIT_SS ( slave ), state );
73  spi_bit_delay();
74 }
75 
76 /**
77  * Transfer bits over SPI bit-bashing bus
78  *
79  * @v bus SPI bus
80  * @v data_out TX data buffer (or NULL)
81  * @v data_in RX data buffer (or NULL)
82  * @v len Length of transfer (in @b bits)
83  * @v endianness Endianness of this data transfer
84  *
85  * This issues @c len clock cycles on the SPI bus, shifting out data
86  * from the @c data_out buffer to the MOSI line and shifting in data
87  * from the MISO line to the @c data_in buffer. If @c data_out is
88  * NULL, then the data sent will be all zeroes. If @c data_in is
89  * NULL, then the incoming data will be discarded.
90  */
91 static void spi_bit_transfer ( struct spi_bit_basher *spibit,
92  const void *data_out, void *data_in,
93  unsigned int len, int endianness ) {
94  struct spi_bus *bus = &spibit->bus;
95  struct bit_basher *basher = &spibit->basher;
96  unsigned int sclk = ( ( bus->mode & SPI_MODE_CPOL ) ? 1 : 0 );
97  unsigned int cpha = ( ( bus->mode & SPI_MODE_CPHA ) ? 1 : 0 );
98  unsigned int bit_offset;
99  unsigned int byte_offset;
100  unsigned int byte_mask;
101  unsigned int bit;
102  unsigned int step;
103 
104  DBGC2 ( spibit, "SPIBIT %p transferring %d bits in mode %#x\n",
105  spibit, len, bus->mode );
106 
107  for ( step = 0 ; step < ( len * 2 ) ; step++ ) {
108  /* Calculate byte offset and byte mask */
109  bit_offset = ( ( endianness == SPI_BIT_BIG_ENDIAN ) ?
110  ( len - ( step / 2 ) - 1 ) : ( step / 2 ) );
111  byte_offset = ( bit_offset / 8 );
112  byte_mask = ( 1 << ( bit_offset % 8 ) );
113 
114  /* Shift data in or out */
115  if ( sclk == cpha ) {
116  const uint8_t *byte;
117 
118  /* Shift data out */
119  if ( data_out ) {
120  byte = ( data_out + byte_offset );
121  bit = ( *byte & byte_mask );
122  DBGCP ( spibit, "SPIBIT %p wrote bit %d\n",
123  spibit, ( bit ? 1 : 0 ) );
124  } else {
125  bit = 0;
126  }
127  write_bit ( basher, SPI_BIT_MOSI, bit );
128  } else {
129  uint8_t *byte;
130 
131  /* Shift data in */
132  bit = read_bit ( basher, SPI_BIT_MISO );
133  if ( data_in ) {
134  DBGCP ( spibit, "SPIBIT %p read bit %d\n",
135  spibit, ( bit ? 1 : 0 ) );
136  byte = ( data_in + byte_offset );
137  *byte &= ~byte_mask;
138  *byte |= ( bit & byte_mask );
139  }
140  }
141 
142  /* Toggle clock line */
143  spi_bit_delay();
144  sclk ^= 1;
145  write_bit ( basher, SPI_BIT_SCLK, sclk );
146  }
147 }
148 
149 /**
150  * Read/write data via SPI bit-bashing bus
151  *
152  * @v bus SPI bus
153  * @v device SPI device
154  * @v command Command
155  * @v address Address to read/write (<0 for no address)
156  * @v data_out TX data buffer (or NULL)
157  * @v data_in RX data buffer (or NULL)
158  * @v len Length of transfer
159  * @ret rc Return status code
160  */
161 static int spi_bit_rw ( struct spi_bus *bus, struct spi_device *device,
162  unsigned int command, int address,
163  const void *data_out, void *data_in, size_t len ) {
164  struct spi_bit_basher *spibit
165  = container_of ( bus, struct spi_bit_basher, bus );
166  uint32_t tmp_command;
167  uint32_t tmp_address;
168  uint32_t tmp_address_detect;
169 
170  /* Open bit-bashing interface */
171  open_bit ( &spibit->basher );
172 
173  /* Deassert chip select to reset specified slave */
174  spi_bit_set_slave_select ( spibit, device->slave, DESELECT_SLAVE );
175 
176  /* Set clock line to idle state */
177  write_bit ( &spibit->basher, SPI_BIT_SCLK,
178  ( bus->mode & SPI_MODE_CPOL ) );
179 
180  /* Assert chip select on specified slave */
181  spi_bit_set_slave_select ( spibit, device->slave, SELECT_SLAVE );
182 
183  /* Transmit command */
184  assert ( device->command_len <= ( 8 * sizeof ( tmp_command ) ) );
185  tmp_command = cpu_to_le32 ( command );
186  spi_bit_transfer ( spibit, &tmp_command, NULL, device->command_len,
188 
189  /* Transmit address, if present */
190  if ( address >= 0 ) {
191  assert ( device->address_len <= ( 8 * sizeof ( tmp_address )));
192  tmp_address = cpu_to_le32 ( address );
193  if ( device->address_len == SPI_AUTODETECT_ADDRESS_LEN ) {
194  /* Autodetect address length. This relies on
195  * the device responding with a dummy zero
196  * data bit before the first real data bit.
197  */
198  DBGC ( spibit, "SPIBIT %p autodetecting device "
199  "address length\n", spibit );
200  assert ( address == 0 );
201  device->address_len = 0;
202  do {
203  spi_bit_transfer ( spibit, &tmp_address,
204  &tmp_address_detect, 1,
206  device->address_len++;
207  } while ( le32_to_cpu ( tmp_address_detect ) & 1 );
208  DBGC ( spibit, "SPIBIT %p autodetected device address "
209  "length %d\n", spibit, device->address_len );
210  } else {
211  spi_bit_transfer ( spibit, &tmp_address, NULL,
212  device->address_len,
214  }
215  }
216 
217  /* Transmit/receive data */
218  spi_bit_transfer ( spibit, data_out, data_in, ( len * 8 ),
219  spibit->endianness );
220 
221  /* Deassert chip select on specified slave */
222  spi_bit_set_slave_select ( spibit, device->slave, DESELECT_SLAVE );
223 
224  /* Close bit-bashing interface */
225  close_bit ( &spibit->basher );
226 
227  return 0;
228 }
229 
230 /**
231  * Initialise SPI bit-bashing interface
232  *
233  * @v spibit SPI bit-bashing interface
234  */
235 void init_spi_bit_basher ( struct spi_bit_basher *spibit ) {
236  assert ( &spibit->basher.op->read != NULL );
237  assert ( &spibit->basher.op->write != NULL );
238  spibit->bus.rw = spi_bit_rw;
239 }
uint8_t slave
Slave.
Definition: edd.h:30
#define SPI_BIT_UDELAY
Delay between SCLK transitions.
Definition: spi_bit.h:53
struct bit_basher basher
Bit-bashing interface.
Definition: spi_bit.h:20
static int spi_bit_rw(struct spi_bus *bus, struct spi_device *device, unsigned int command, int address, const void *data_out, void *data_in, size_t len)
Read/write data via SPI bit-bashing bus.
Definition: spi_bit.c:161
FILE_LICENCE(GPL2_OR_LATER_OR_UBDL)
int(* rw)(struct spi_bus *bus, struct spi_device *device, unsigned int command, int address, const void *data_out, void *data_in, size_t len)
Read/write data via SPI bus.
Definition: spi.h:152
static void spi_bit_set_slave_select(struct spi_bit_basher *spibit, unsigned int slave, unsigned int state)
Select/deselect slave.
Definition: spi_bit.c:62
static void open_bit(struct bit_basher *basher)
Open bit-bashing interface.
Definition: bitbash.h:65
uint8_t state
State.
Definition: eth_slow.h:47
static unsigned int unsigned int bit
Definition: bigint.h:205
#define le32_to_cpu(value)
Definition: byteswap.h:113
Error codes.
SPI bit-bashing interface.
A command-line command.
Definition: command.h:9
uint64_t address
Base address.
Definition: ena.h:24
An SPI bus.
Definition: spi.h:126
#define DBGC(...)
Definition: compiler.h:505
#define SPI_MODE_CPHA
Clock phase (CPHA) mode bit.
Definition: spi.h:163
#define SPI_MODE_CPOL
Clock polarity (CPOL) mode bit.
Definition: spi.h:169
Master In Slave Out.
Definition: spi_bit.h:39
struct bit_basher_operations * op
Bit-bashing operations.
Definition: bitbash.h:57
unsigned int mode
SPI interface mode.
Definition: spi.h:136
A hardware device.
Definition: device.h:73
Assertions.
assert((readw(&hdr->flags) &(GTF_reading|GTF_writing))==0)
#define container_of(ptr, type, field)
Get containing structure.
Definition: stddef.h:35
void init_spi_bit_basher(struct spi_bit_basher *spibit)
Initialise SPI bit-bashing interface.
Definition: spi_bit.c:235
void udelay(unsigned long usecs)
Delay for a fixed number of microseconds.
Definition: timer.c:60
Bit-bashing interfaces.
Master Out Slave In.
Definition: spi_bit.h:37
A bit-bashing SPI bus.
Definition: spi_bit.h:16
#define cpu_to_le32(value)
Definition: byteswap.h:107
int(* read)(struct bit_basher *basher, unsigned int bit_id)
Read input bit.
Definition: bitbash.h:51
A bit-bashing interface.
Definition: bitbash.h:55
#define DESELECT_SLAVE
Chip select line will be deasserted.
Definition: spi_bit.c:51
Serial clock.
Definition: spi_bit.h:35
#define SPI_BIT_SS(slave)
Determine bit index for a particular slave.
Definition: spi_bit.h:50
unsigned char uint8_t
Definition: stdint.h:10
static void spi_bit_transfer(struct spi_bit_basher *spibit, const void *data_out, void *data_in, unsigned int len, int endianness)
Transfer bits over SPI bit-bashing bus.
Definition: spi_bit.c:91
unsigned int uint32_t
Definition: stdint.h:12
unsigned char byte
Definition: smc9000.h:38
struct spi_bus bus
SPI bus.
Definition: spi_bit.h:18
int read_bit(struct bit_basher *basher, unsigned int bit_id)
Read input bit.
Definition: bitbash.c:60
#define SPI_MODE_SSPOL
Slave select polarity mode bit.
Definition: spi.h:178
#define SPI_BIT_BIG_ENDIAN
SPI bit basher treats data as big-endian.
Definition: spi_bit.h:56
void(* write)(struct bit_basher *basher, unsigned int bit_id, unsigned long data)
Set/clear output bit.
Definition: bitbash.h:41
uint32_t len
Length.
Definition: ena.h:14
#define DBGC2(...)
Definition: compiler.h:522
void step(void)
Single-step a single process.
Definition: process.c:98
#define SELECT_SLAVE
Chip select line will be asserted.
Definition: spi_bit.c:48
#define DBGCP(...)
Definition: compiler.h:539
An SPI device.
Definition: spi.h:86
static void close_bit(struct bit_basher *basher)
Close bit-bashing interface.
Definition: bitbash.h:75
static void spi_bit_delay(void)
Delay between SCLK changes and around SS changes.
Definition: spi_bit.c:43
#define NULL
NULL pointer (VOID *)
Definition: Base.h:362
String functions.
uint8_t bus
Bus.
Definition: edd.h:14
#define SPI_AUTODETECT_ADDRESS_LEN
SPI magic autodetection address length.
Definition: spi.h:113
void write_bit(struct bit_basher *basher, unsigned int bit_id, unsigned long data)
Set/clear output bit.
Definition: bitbash.c:44
int endianness
Endianness of data.
Definition: spi_bit.h:29