1 /******************************************************************************
2 * *
3 * License Agreement *
4 * *
5 * Copyright (c) 2003 Altera Corporation, San Jose, California, USA. *
6 * All rights reserved. *
7 * *
8 * Permission is hereby granted, free of charge, to any person obtaining a *
9 * copy of this software and associated documentation files (the "Software"), *
10 * to deal in the Software without restriction, including without limitation *
11 * the rights to use, copy, modify, merge, publish, distribute, sublicense, *
12 * and/or sell copies of the Software, and to permit persons to whom the *
13 * Software is furnished to do so, subject to the following conditions: *
14 * *
15 * The above copyright notice and this permission notice shall be included in *
16 * all copies or substantial portions of the Software. *
17 * *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR *
19 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, *
20 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE *
21 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER *
22 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING *
23 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER *
24 * DEALINGS IN THE SOFTWARE. *
25 * *
26 * *
27 ******************************************************************************/
28
29 #include "alt_types.h"
30
31 #include "altera_avalon_spi_regs.h"
32 #include "altera_avalon_spi.h"
33
34 /* This is a very simple routine which performs one SPI master transaction.
35 * It would be possible to implement a more efficient version using interrupts
36 * and sleeping threads but this is probably not worthwhile initially.
37 */
38
alt_avalon_spi_command(alt_u32 base,alt_u32 slave,alt_u32 write_length,const alt_u8 * write_data,alt_u32 read_length,alt_u8 * read_data,alt_u32 flags)39 int alt_avalon_spi_command(alt_u32 base, alt_u32 slave,
40 alt_u32 write_length, const alt_u8 * write_data,
41 alt_u32 read_length, alt_u8 * read_data,
42 alt_u32 flags)
43 {
44 const alt_u8 * write_end = write_data + write_length;
45 alt_u8 * read_end = read_data + read_length;
46
47 alt_u32 write_zeros = read_length;
48 alt_u32 read_ignore = write_length;
49 alt_u32 status;
50
51 /* We must not send more than two bytes to the target before it has
52 * returned any as otherwise it will overflow. */
53 /* Unfortunately the hardware does not seem to work with credits > 1,
54 * leave it at 1 for now. */
55 alt_32 credits = 1;
56
57 /* Warning: this function is not currently safe if called in a multi-threaded
58 * environment, something above must perform locking to make it safe if more
59 * than one thread intends to use it.
60 */
61
62 IOWR_ALTERA_AVALON_SPI_SLAVE_SEL(base, 1 << slave);
63
64 /* Set the SSO bit (force chipselect) only if the toggle flag is not set */
65 if ((flags & ALT_AVALON_SPI_COMMAND_TOGGLE_SS_N) == 0) {
66 IOWR_ALTERA_AVALON_SPI_CONTROL(base, ALTERA_AVALON_SPI_CONTROL_SSO_MSK);
67 }
68
69 /*
70 * Discard any stale data present in the RXDATA register, in case
71 * previous communication was interrupted and stale data was left
72 * behind.
73 */
74 IORD_ALTERA_AVALON_SPI_RXDATA(base);
75
76 /* Keep clocking until all the data has been processed. */
77 for ( ; ; )
78 {
79
80 do
81 {
82 status = IORD_ALTERA_AVALON_SPI_STATUS(base);
83 }
84 while (((status & ALTERA_AVALON_SPI_STATUS_TRDY_MSK) == 0 || credits == 0) &&
85 (status & ALTERA_AVALON_SPI_STATUS_RRDY_MSK) == 0);
86
87 if ((status & ALTERA_AVALON_SPI_STATUS_TRDY_MSK) != 0 && credits > 0)
88 {
89 credits--;
90
91 if (write_data < write_end)
92 IOWR_ALTERA_AVALON_SPI_TXDATA(base, *write_data++);
93 else if (write_zeros > 0)
94 {
95 write_zeros--;
96 IOWR_ALTERA_AVALON_SPI_TXDATA(base, 0);
97 }
98 else
99 credits = -1024;
100 };
101
102 if ((status & ALTERA_AVALON_SPI_STATUS_RRDY_MSK) != 0)
103 {
104 alt_u32 rxdata = IORD_ALTERA_AVALON_SPI_RXDATA(base);
105
106 if (read_ignore > 0)
107 read_ignore--;
108 else
109 *read_data++ = (alt_u8)rxdata;
110 credits++;
111
112 if (read_ignore == 0 && read_data == read_end)
113 break;
114 }
115
116 }
117
118 /* Wait until the interface has finished transmitting */
119 do
120 {
121 status = IORD_ALTERA_AVALON_SPI_STATUS(base);
122 }
123 while ((status & ALTERA_AVALON_SPI_STATUS_TMT_MSK) == 0);
124
125 /* Clear SSO (release chipselect) unless the caller is going to
126 * keep using this chip
127 */
128 if ((flags & ALT_AVALON_SPI_COMMAND_MERGE) == 0)
129 IOWR_ALTERA_AVALON_SPI_CONTROL(base, 0);
130
131 return read_length;
132 }
133
