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 <string.h>
23 #include <assert.h>
24 #include <unistd.h>
25 #include <gpxe/threewire.h>
26
27 /** @file
28 *
29 * Three-wire serial devices
30 *
31 */
32
33 /**
34 * Read data from three-wire device
35 *
36 * @v nvs NVS device
37 * @v address Address from which to read
38 * @v data Data buffer
39 * @v len Length of data buffer
40 * @ret rc Return status code
41 */
threewire_read(struct nvs_device * nvs,unsigned int address,void * data,size_t len)42 int threewire_read ( struct nvs_device *nvs, unsigned int address,
43 void *data, size_t len ) {
44 struct spi_device *device = nvs_to_spi ( nvs );
45 struct spi_bus *bus = device->bus;
46 int rc;
47
48 assert ( bus->mode == SPI_MODE_THREEWIRE );
49
50 DBGC ( device, "3wire %p reading %zd bytes at %04x\n",
51 device, len, address );
52
53 if ( ( rc = bus->rw ( bus, device, THREEWIRE_READ, address,
54 NULL, data, len ) ) != 0 ) {
55 DBGC ( device, "3wire %p could not read: %s\n",
56 device, strerror ( rc ) );
57 return rc;
58 }
59
60 return 0;
61 }
62
63 /**
64 * Write data to three-wire device
65 *
66 * @v nvs NVS device
67 * @v address Address from which to read
68 * @v data Data buffer
69 * @v len Length of data buffer
70 * @ret rc Return status code
71 */
threewire_write(struct nvs_device * nvs,unsigned int address,const void * data,size_t len)72 int threewire_write ( struct nvs_device *nvs, unsigned int address,
73 const void *data, size_t len ) {
74 struct spi_device *device = nvs_to_spi ( nvs );
75 struct spi_bus *bus = device->bus;
76 int rc;
77
78 assert ( bus->mode == SPI_MODE_THREEWIRE );
79
80 DBGC ( device, "3wire %p writing %zd bytes at %04x\n",
81 device, len, address );
82
83 /* Enable device for writing */
84 if ( ( rc = bus->rw ( bus, device, THREEWIRE_EWEN,
85 THREEWIRE_EWEN_ADDRESS, NULL, NULL, 0 ) ) != 0 ){
86 DBGC ( device, "3wire %p could not enable writing: %s\n",
87 device, strerror ( rc ) );
88 return rc;
89 }
90
91 /* Write data */
92 if ( ( rc = bus->rw ( bus, device, THREEWIRE_WRITE, address,
93 data, NULL, len ) ) != 0 ) {
94 DBGC ( device, "3wire %p could not write: %s\n",
95 device, strerror ( rc ) );
96 return rc;
97 }
98
99 /* Our model of an SPI bus doesn't provide a mechanism for
100 * "assert CS, wait for MISO to become high, so just wait for
101 * long enough to ensure that the write has completed.
102 */
103 mdelay ( THREEWIRE_WRITE_MDELAY );
104
105 return 0;
106 }
107
108 /**
109 * Autodetect device address length
110 *
111 * @v device SPI device
112 * @ret rc Return status code
113 */
threewire_detect_address_len(struct spi_device * device)114 int threewire_detect_address_len ( struct spi_device *device ) {
115 struct nvs_device *nvs = &device->nvs;
116 int rc;
117
118 DBGC ( device, "3wire %p autodetecting address length\n", device );
119
120 device->address_len = SPI_AUTODETECT_ADDRESS_LEN;
121 if ( ( rc = threewire_read ( nvs, 0, NULL,
122 ( 1 << nvs->word_len_log2 ) ) ) != 0 ) {
123 DBGC ( device, "3wire %p could not autodetect address "
124 "length: %s\n", device, strerror ( rc ) );
125 return rc;
126 }
127
128 DBGC ( device, "3wire %p autodetected address length %d\n",
129 device, device->address_len );
130 return 0;
131 }
132