1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * Copyright (c) 2014 Google, Inc
4 *
5 * (C) Copyright 2002
6 * Gerald Van Baren, Custom IDEAS, vanbaren@cideas.com.
7 *
8 * Influenced by code from:
9 * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
10 */
11
12 #include <common.h>
13 #include <dm.h>
14 #include <errno.h>
15 #include <fdtdec.h>
16 #include <malloc.h>
17 #include <spi.h>
18 #include <asm/gpio.h>
19
20 DECLARE_GLOBAL_DATA_PTR;
21
22 struct soft_spi_platdata {
23 struct gpio_desc cs;
24 struct gpio_desc sclk;
25 struct gpio_desc mosi;
26 struct gpio_desc miso;
27 int spi_delay_us;
28 int flags;
29 };
30
31 #define SPI_MASTER_NO_RX BIT(0)
32 #define SPI_MASTER_NO_TX BIT(1)
33
34 struct soft_spi_priv {
35 unsigned int mode;
36 };
37
soft_spi_scl(struct udevice * dev,int bit)38 static int soft_spi_scl(struct udevice *dev, int bit)
39 {
40 struct udevice *bus = dev_get_parent(dev);
41 struct soft_spi_platdata *plat = dev_get_platdata(bus);
42
43 dm_gpio_set_value(&plat->sclk, bit);
44
45 return 0;
46 }
47
soft_spi_sda(struct udevice * dev,int bit)48 static int soft_spi_sda(struct udevice *dev, int bit)
49 {
50 struct udevice *bus = dev_get_parent(dev);
51 struct soft_spi_platdata *plat = dev_get_platdata(bus);
52
53 dm_gpio_set_value(&plat->mosi, bit);
54
55 return 0;
56 }
57
soft_spi_cs_activate(struct udevice * dev)58 static int soft_spi_cs_activate(struct udevice *dev)
59 {
60 struct udevice *bus = dev_get_parent(dev);
61 struct soft_spi_platdata *plat = dev_get_platdata(bus);
62
63 dm_gpio_set_value(&plat->cs, 0);
64 dm_gpio_set_value(&plat->sclk, 0);
65 dm_gpio_set_value(&plat->cs, 1);
66
67 return 0;
68 }
69
soft_spi_cs_deactivate(struct udevice * dev)70 static int soft_spi_cs_deactivate(struct udevice *dev)
71 {
72 struct udevice *bus = dev_get_parent(dev);
73 struct soft_spi_platdata *plat = dev_get_platdata(bus);
74
75 dm_gpio_set_value(&plat->cs, 0);
76
77 return 0;
78 }
79
soft_spi_claim_bus(struct udevice * dev)80 static int soft_spi_claim_bus(struct udevice *dev)
81 {
82 /*
83 * Make sure the SPI clock is in idle state as defined for
84 * this slave.
85 */
86 return soft_spi_scl(dev, 0);
87 }
88
soft_spi_release_bus(struct udevice * dev)89 static int soft_spi_release_bus(struct udevice *dev)
90 {
91 /* Nothing to do */
92 return 0;
93 }
94
95 /*-----------------------------------------------------------------------
96 * SPI transfer
97 *
98 * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks
99 * "bitlen" bits in the SPI MISO port. That's just the way SPI works.
100 *
101 * The source of the outgoing bits is the "dout" parameter and the
102 * destination of the input bits is the "din" parameter. Note that "dout"
103 * and "din" can point to the same memory location, in which case the
104 * input data overwrites the output data (since both are buffered by
105 * temporary variables, this is OK).
106 */
soft_spi_xfer(struct udevice * dev,unsigned int bitlen,const void * dout,void * din,unsigned long flags)107 static int soft_spi_xfer(struct udevice *dev, unsigned int bitlen,
108 const void *dout, void *din, unsigned long flags)
109 {
110 struct udevice *bus = dev_get_parent(dev);
111 struct soft_spi_priv *priv = dev_get_priv(bus);
112 struct soft_spi_platdata *plat = dev_get_platdata(bus);
113 uchar tmpdin = 0;
114 uchar tmpdout = 0;
115 const u8 *txd = dout;
116 u8 *rxd = din;
117 int cpha = priv->mode & SPI_CPHA;
118 unsigned int j;
119
120 debug("spi_xfer: slave %s:%s dout %08X din %08X bitlen %u\n",
121 dev->parent->name, dev->name, *(uint *)txd, *(uint *)rxd,
122 bitlen);
123
124 if (flags & SPI_XFER_BEGIN)
125 soft_spi_cs_activate(dev);
126
127 for (j = 0; j < bitlen; j++) {
128 /*
129 * Check if it is time to work on a new byte.
130 */
131 if ((j % 8) == 0) {
132 if (txd)
133 tmpdout = *txd++;
134 else
135 tmpdout = 0;
136 if (j != 0) {
137 if (rxd)
138 *rxd++ = tmpdin;
139 }
140 tmpdin = 0;
141 }
142
143 if (!cpha)
144 soft_spi_scl(dev, 0);
145 if ((plat->flags & SPI_MASTER_NO_TX) == 0)
146 soft_spi_sda(dev, !!(tmpdout & 0x80));
147 udelay(plat->spi_delay_us);
148 if (cpha)
149 soft_spi_scl(dev, 0);
150 else
151 soft_spi_scl(dev, 1);
152 tmpdin <<= 1;
153 if ((plat->flags & SPI_MASTER_NO_RX) == 0)
154 tmpdin |= dm_gpio_get_value(&plat->miso);
155 tmpdout <<= 1;
156 udelay(plat->spi_delay_us);
157 if (cpha)
158 soft_spi_scl(dev, 1);
159 }
160 /*
161 * If the number of bits isn't a multiple of 8, shift the last
162 * bits over to left-justify them. Then store the last byte
163 * read in.
164 */
165 if (rxd) {
166 if ((bitlen % 8) != 0)
167 tmpdin <<= 8 - (bitlen % 8);
168 *rxd++ = tmpdin;
169 }
170
171 if (flags & SPI_XFER_END)
172 soft_spi_cs_deactivate(dev);
173
174 return 0;
175 }
176
soft_spi_set_speed(struct udevice * dev,unsigned int speed)177 static int soft_spi_set_speed(struct udevice *dev, unsigned int speed)
178 {
179 /* Accept any speed */
180 return 0;
181 }
182
soft_spi_set_mode(struct udevice * dev,unsigned int mode)183 static int soft_spi_set_mode(struct udevice *dev, unsigned int mode)
184 {
185 struct soft_spi_priv *priv = dev_get_priv(dev);
186
187 priv->mode = mode;
188
189 return 0;
190 }
191
192 static const struct dm_spi_ops soft_spi_ops = {
193 .claim_bus = soft_spi_claim_bus,
194 .release_bus = soft_spi_release_bus,
195 .xfer = soft_spi_xfer,
196 .set_speed = soft_spi_set_speed,
197 .set_mode = soft_spi_set_mode,
198 };
199
soft_spi_ofdata_to_platdata(struct udevice * dev)200 static int soft_spi_ofdata_to_platdata(struct udevice *dev)
201 {
202 struct soft_spi_platdata *plat = dev->platdata;
203 const void *blob = gd->fdt_blob;
204 int node = dev_of_offset(dev);
205
206 plat->spi_delay_us = fdtdec_get_int(blob, node, "spi-delay-us", 0);
207
208 return 0;
209 }
210
soft_spi_probe(struct udevice * dev)211 static int soft_spi_probe(struct udevice *dev)
212 {
213 struct spi_slave *slave = dev_get_parent_priv(dev);
214 struct soft_spi_platdata *plat = dev->platdata;
215 int cs_flags, clk_flags;
216 int ret;
217
218 cs_flags = (slave->mode & SPI_CS_HIGH) ? 0 : GPIOD_ACTIVE_LOW;
219 clk_flags = (slave->mode & SPI_CPOL) ? GPIOD_ACTIVE_LOW : 0;
220
221 if (gpio_request_by_name(dev, "cs-gpios", 0, &plat->cs,
222 GPIOD_IS_OUT | cs_flags) ||
223 gpio_request_by_name(dev, "gpio-sck", 0, &plat->sclk,
224 GPIOD_IS_OUT | clk_flags))
225 return -EINVAL;
226
227 ret = gpio_request_by_name(dev, "gpio-mosi", 0, &plat->mosi,
228 GPIOD_IS_OUT | GPIOD_IS_OUT_ACTIVE);
229 if (ret)
230 plat->flags |= SPI_MASTER_NO_TX;
231
232 ret = gpio_request_by_name(dev, "gpio-miso", 0, &plat->miso,
233 GPIOD_IS_IN);
234 if (ret)
235 plat->flags |= SPI_MASTER_NO_RX;
236
237 if ((plat->flags & (SPI_MASTER_NO_RX | SPI_MASTER_NO_TX)) ==
238 (SPI_MASTER_NO_RX | SPI_MASTER_NO_TX))
239 return -EINVAL;
240
241 return 0;
242 }
243
244 static const struct udevice_id soft_spi_ids[] = {
245 { .compatible = "spi-gpio" },
246 { }
247 };
248
249 U_BOOT_DRIVER(soft_spi) = {
250 .name = "soft_spi",
251 .id = UCLASS_SPI,
252 .of_match = soft_spi_ids,
253 .ops = &soft_spi_ops,
254 .ofdata_to_platdata = soft_spi_ofdata_to_platdata,
255 .platdata_auto_alloc_size = sizeof(struct soft_spi_platdata),
256 .priv_auto_alloc_size = sizeof(struct soft_spi_priv),
257 .probe = soft_spi_probe,
258 };
259