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., 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 <gpxe/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 */
spi_command(unsigned int command,unsigned int address,int munge_address)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 */
spi_wait(struct spi_device * device)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 */
spi_read(struct nvs_device * nvs,unsigned int address,void * data,size_t len)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 */
spi_write(struct nvs_device * nvs,unsigned int address,const void * data,size_t len)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
141