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1.1 root 1: /*
2: * Copyright (C) 2006 Michael Brown <[email protected]>.
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., 675 Mass Ave, Cambridge, MA 02139, USA.
17: */
18:
19: FILE_LICENCE ( GPL2_OR_LATER );
20:
21: #include <stddef.h>
22: #include <errno.h>
23: #include <unistd.h>
24: #include <ipxe/spi.h>
25:
26: /** @file
27: *
28: * SPI devices
29: *
30: */
31:
32: /**
33: * Munge SPI device address into command
34: *
35: * @v command SPI command
36: * @v address Address
37: * @v munge_address Device requires address munging
38: * @ret command Actual SPI command to use
39: *
40: * Some devices with 9-bit addresses (e.g. AT25040A EEPROM) use bit 3
41: * of the command byte as address bit A8, rather than having a
42: * two-byte address. This function takes care of generating the
43: * appropriate command.
44: */
45: static inline unsigned int spi_command ( unsigned int command,
46: unsigned int address,
47: int munge_address ) {
48: return ( command | ( ( ( address >> 8 ) & munge_address ) << 3 ) );
49: }
50:
51: /**
52: * Wait for SPI device to complete operation
53: *
54: * @v device SPI device
55: * @ret rc Return status code
56: */
57: static int spi_wait ( struct spi_device *device ) {
58: struct spi_bus *bus = device->bus;
59: uint8_t status;
60: int i;
61: int rc;
62:
63: for ( i = 0 ; i < 50 ; i++ ) {
64: udelay ( 20 );
65: if ( ( rc = bus->rw ( bus, device, SPI_RDSR, -1, NULL,
66: &status, sizeof ( status ) ) ) != 0 )
67: return rc;
68: if ( ! ( status & SPI_STATUS_NRDY ) )
69: return 0;
70: }
71: DBG ( "SPI %p timed out\n", device );
72: return -ETIMEDOUT;
73: }
74:
75: /**
76: * Read data from SPI device
77: *
78: * @v nvs NVS device
79: * @v address Address from which to read
80: * @v data Data buffer
81: * @v len Length of data buffer
82: * @ret rc Return status code
83: */
84: int spi_read ( struct nvs_device *nvs, unsigned int address,
85: void *data, size_t len ) {
86: struct spi_device *device = nvs_to_spi ( nvs );
87: struct spi_bus *bus = device->bus;
88: unsigned int command = spi_command ( SPI_READ, address,
89: device->munge_address );
90: int rc;
91:
92: DBG ( "SPI %p reading %zd bytes from %#04x\n", device, len, address );
93: if ( ( rc = bus->rw ( bus, device, command, address,
94: NULL, data, len ) ) != 0 ) {
95: DBG ( "SPI %p failed to read data from device\n", device );
96: return rc;
97: }
98:
99: return 0;
100: }
101:
102: /**
103: * Write data to SPI device
104: *
105: * @v nvs NVS device
106: * @v address Address from which to read
107: * @v data Data buffer
108: * @v len Length of data buffer
109: * @ret rc Return status code
110: */
111: int spi_write ( struct nvs_device *nvs, unsigned int address,
112: const void *data, size_t len ) {
113: struct spi_device *device = nvs_to_spi ( nvs );
114: struct spi_bus *bus = device->bus;
115: unsigned int command = spi_command ( SPI_WRITE, address,
116: device->munge_address );
117: int rc;
118:
119: DBG ( "SPI %p writing %zd bytes to %#04x\n", device, len, address );
120:
121: if ( ( rc = bus->rw ( bus, device, SPI_WREN, -1,
122: NULL, NULL, 0 ) ) != 0 ) {
123: DBG ( "SPI %p failed to write-enable device\n", device );
124: return rc;
125: }
126:
127: if ( ( rc = bus->rw ( bus, device, command, address,
128: data, NULL, len ) ) != 0 ) {
129: DBG ( "SPI %p failed to write data to device\n", device );
130: return rc;
131: }
132:
133: if ( ( rc = spi_wait ( device ) ) != 0 ) {
134: DBG ( "SPI %p failed to complete write operation\n", device );
135: return rc;
136: }
137:
138: return 0;
139: }
140:
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