1 /*
2 * (C) Copyright 2002
3 * Gerald Van Baren, Custom IDEAS, vanbaren@cideas.com.
4 *
5 * Influenced by code from:
6 * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
7 *
8 * SPDX-License-Identifier: GPL-2.0+
9 */
10
11 #include <common.h>
12 #include <spi.h>
13
14 #include <malloc.h>
15
16 /*-----------------------------------------------------------------------
17 * Definitions
18 */
19
20 #ifdef DEBUG_SPI
21 #define PRINTD(fmt,args...) printf (fmt ,##args)
22 #else
23 #define PRINTD(fmt,args...)
24 #endif
25
26 struct soft_spi_slave {
27 struct spi_slave slave;
28 unsigned int mode;
29 };
30
to_soft_spi(struct spi_slave * slave)31 static inline struct soft_spi_slave *to_soft_spi(struct spi_slave *slave)
32 {
33 return container_of(slave, struct soft_spi_slave, slave);
34 }
35
36 /*=====================================================================*/
37 /* Public Functions */
38 /*=====================================================================*/
39
40 /*-----------------------------------------------------------------------
41 * Initialization
42 */
spi_init(void)43 void spi_init (void)
44 {
45 }
46
spi_setup_slave(unsigned int bus,unsigned int cs,unsigned int max_hz,unsigned int mode)47 struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
48 unsigned int max_hz, unsigned int mode)
49 {
50 struct soft_spi_slave *ss;
51
52 if (!spi_cs_is_valid(bus, cs))
53 return NULL;
54
55 ss = spi_alloc_slave(struct soft_spi_slave, bus, cs);
56 if (!ss)
57 return NULL;
58
59 ss->mode = mode;
60
61 /* TODO: Use max_hz to limit the SCK rate */
62
63 return &ss->slave;
64 }
65
spi_free_slave(struct spi_slave * slave)66 void spi_free_slave(struct spi_slave *slave)
67 {
68 struct soft_spi_slave *ss = to_soft_spi(slave);
69
70 free(ss);
71 }
72
spi_claim_bus(struct spi_slave * slave)73 int spi_claim_bus(struct spi_slave *slave)
74 {
75 #ifdef CONFIG_SYS_IMMR
76 volatile immap_t *immr = (immap_t *)CONFIG_SYS_IMMR;
77 #endif
78 struct soft_spi_slave *ss = to_soft_spi(slave);
79
80 /*
81 * Make sure the SPI clock is in idle state as defined for
82 * this slave.
83 */
84 if (ss->mode & SPI_CPOL)
85 SPI_SCL(1);
86 else
87 SPI_SCL(0);
88
89 return 0;
90 }
91
spi_release_bus(struct spi_slave * slave)92 void spi_release_bus(struct spi_slave *slave)
93 {
94 /* Nothing to do */
95 }
96
97 /*-----------------------------------------------------------------------
98 * SPI transfer
99 *
100 * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks
101 * "bitlen" bits in the SPI MISO port. That's just the way SPI works.
102 *
103 * The source of the outgoing bits is the "dout" parameter and the
104 * destination of the input bits is the "din" parameter. Note that "dout"
105 * and "din" can point to the same memory location, in which case the
106 * input data overwrites the output data (since both are buffered by
107 * temporary variables, this is OK).
108 */
spi_xfer(struct spi_slave * slave,unsigned int bitlen,const void * dout,void * din,unsigned long flags)109 int spi_xfer(struct spi_slave *slave, unsigned int bitlen,
110 const void *dout, void *din, unsigned long flags)
111 {
112 #ifdef CONFIG_SYS_IMMR
113 volatile immap_t *immr = (immap_t *)CONFIG_SYS_IMMR;
114 #endif
115 struct soft_spi_slave *ss = to_soft_spi(slave);
116 uchar tmpdin = 0;
117 uchar tmpdout = 0;
118 const u8 *txd = dout;
119 u8 *rxd = din;
120 int cpol = ss->mode & SPI_CPOL;
121 int cpha = ss->mode & SPI_CPHA;
122 unsigned int j;
123
124 PRINTD("spi_xfer: slave %u:%u dout %08X din %08X bitlen %u\n",
125 slave->bus, slave->cs, *(uint *)txd, *(uint *)rxd, bitlen);
126
127 if (flags & SPI_XFER_BEGIN)
128 spi_cs_activate(slave);
129
130 for(j = 0; j < bitlen; j++) {
131 /*
132 * Check if it is time to work on a new byte.
133 */
134 if ((j % 8) == 0) {
135 if (txd)
136 tmpdout = *txd++;
137 else
138 tmpdout = 0;
139 if(j != 0) {
140 if (rxd)
141 *rxd++ = tmpdin;
142 }
143 tmpdin = 0;
144 }
145
146 if (!cpha)
147 SPI_SCL(!cpol);
148 SPI_SDA(tmpdout & 0x80);
149 SPI_DELAY;
150 if (cpha)
151 SPI_SCL(!cpol);
152 else
153 SPI_SCL(cpol);
154 tmpdin <<= 1;
155 tmpdin |= SPI_READ;
156 tmpdout <<= 1;
157 SPI_DELAY;
158 if (cpha)
159 SPI_SCL(cpol);
160 }
161 /*
162 * If the number of bits isn't a multiple of 8, shift the last
163 * bits over to left-justify them. Then store the last byte
164 * read in.
165 */
166 if (rxd) {
167 if ((bitlen % 8) != 0)
168 tmpdin <<= 8 - (bitlen % 8);
169 *rxd++ = tmpdin;
170 }
171
172 if (flags & SPI_XFER_END)
173 spi_cs_deactivate(slave);
174
175 return(0);
176 }
177