1 /*
2 * Copyright (c) 2014 Google, Inc
3 *
4 * (C) Copyright 2002
5 * Gerald Van Baren, Custom IDEAS, vanbaren@cideas.com.
6 *
7 * Influenced by code from:
8 * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
9 *
10 * SPDX-License-Identifier: GPL-2.0+
11 */
12
13 #include <common.h>
14 #include <dm.h>
15 #include <errno.h>
16 #include <fdtdec.h>
17 #include <malloc.h>
18 #include <spi.h>
19 #include <asm/gpio.h>
20
21 DECLARE_GLOBAL_DATA_PTR;
22
23 struct soft_spi_platdata {
24 struct gpio_desc cs;
25 struct gpio_desc sclk;
26 struct gpio_desc mosi;
27 struct gpio_desc miso;
28 int spi_delay_us;
29 int flags;
30 };
31
32 #define SPI_MASTER_NO_RX BIT(0)
33 #define SPI_MASTER_NO_TX BIT(1)
34
35 struct soft_spi_priv {
36 unsigned int mode;
37 };
38
soft_spi_scl(struct udevice * dev,int bit)39 static int soft_spi_scl(struct udevice *dev, int bit)
40 {
41 struct udevice *bus = dev_get_parent(dev);
42 struct soft_spi_platdata *plat = dev_get_platdata(bus);
43
44 dm_gpio_set_value(&plat->sclk, bit);
45
46 return 0;
47 }
48
soft_spi_sda(struct udevice * dev,int bit)49 static int soft_spi_sda(struct udevice *dev, int bit)
50 {
51 struct udevice *bus = dev_get_parent(dev);
52 struct soft_spi_platdata *plat = dev_get_platdata(bus);
53
54 dm_gpio_set_value(&plat->mosi, bit);
55
56 return 0;
57 }
58
soft_spi_cs_activate(struct udevice * dev)59 static int soft_spi_cs_activate(struct udevice *dev)
60 {
61 struct udevice *bus = dev_get_parent(dev);
62 struct soft_spi_platdata *plat = dev_get_platdata(bus);
63
64 dm_gpio_set_value(&plat->cs, 0);
65 dm_gpio_set_value(&plat->sclk, 0);
66 dm_gpio_set_value(&plat->cs, 1);
67
68 return 0;
69 }
70
soft_spi_cs_deactivate(struct udevice * dev)71 static int soft_spi_cs_deactivate(struct udevice *dev)
72 {
73 struct udevice *bus = dev_get_parent(dev);
74 struct soft_spi_platdata *plat = dev_get_platdata(bus);
75
76 dm_gpio_set_value(&plat->cs, 0);
77
78 return 0;
79 }
80
soft_spi_claim_bus(struct udevice * dev)81 static int soft_spi_claim_bus(struct udevice *dev)
82 {
83 /*
84 * Make sure the SPI clock is in idle state as defined for
85 * this slave.
86 */
87 return soft_spi_scl(dev, 0);
88 }
89
soft_spi_release_bus(struct udevice * dev)90 static int soft_spi_release_bus(struct udevice *dev)
91 {
92 /* Nothing to do */
93 return 0;
94 }
95
96 /*-----------------------------------------------------------------------
97 * SPI transfer
98 *
99 * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks
100 * "bitlen" bits in the SPI MISO port. That's just the way SPI works.
101 *
102 * The source of the outgoing bits is the "dout" parameter and the
103 * destination of the input bits is the "din" parameter. Note that "dout"
104 * and "din" can point to the same memory location, in which case the
105 * input data overwrites the output data (since both are buffered by
106 * temporary variables, this is OK).
107 */
soft_spi_xfer(struct udevice * dev,unsigned int bitlen,const void * dout,void * din,unsigned long flags)108 static int soft_spi_xfer(struct udevice *dev, unsigned int bitlen,
109 const void *dout, void *din, unsigned long flags)
110 {
111 struct udevice *bus = dev_get_parent(dev);
112 struct soft_spi_priv *priv = dev_get_priv(bus);
113 struct soft_spi_platdata *plat = dev_get_platdata(bus);
114 uchar tmpdin = 0;
115 uchar tmpdout = 0;
116 const u8 *txd = dout;
117 u8 *rxd = din;
118 int cpha = priv->mode & SPI_CPHA;
119 unsigned int j;
120
121 debug("spi_xfer: slave %s:%s dout %08X din %08X bitlen %u\n",
122 dev->parent->name, dev->name, *(uint *)txd, *(uint *)rxd,
123 bitlen);
124
125 if (flags & SPI_XFER_BEGIN)
126 soft_spi_cs_activate(dev);
127
128 for (j = 0; j < bitlen; j++) {
129 /*
130 * Check if it is time to work on a new byte.
131 */
132 if ((j % 8) == 0) {
133 if (txd)
134 tmpdout = *txd++;
135 else
136 tmpdout = 0;
137 if (j != 0) {
138 if (rxd)
139 *rxd++ = tmpdin;
140 }
141 tmpdin = 0;
142 }
143
144 if (!cpha)
145 soft_spi_scl(dev, 0);
146 if ((plat->flags & SPI_MASTER_NO_TX) == 0)
147 soft_spi_sda(dev, !!(tmpdout & 0x80));
148 udelay(plat->spi_delay_us);
149 if (cpha)
150 soft_spi_scl(dev, 0);
151 else
152 soft_spi_scl(dev, 1);
153 tmpdin <<= 1;
154 if ((plat->flags & SPI_MASTER_NO_RX) == 0)
155 tmpdin |= dm_gpio_get_value(&plat->miso);
156 tmpdout <<= 1;
157 udelay(plat->spi_delay_us);
158 if (cpha)
159 soft_spi_scl(dev, 1);
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 soft_spi_cs_deactivate(dev);
174
175 return 0;
176 }
177
soft_spi_set_speed(struct udevice * dev,unsigned int speed)178 static int soft_spi_set_speed(struct udevice *dev, unsigned int speed)
179 {
180 /* Accept any speed */
181 return 0;
182 }
183
soft_spi_set_mode(struct udevice * dev,unsigned int mode)184 static int soft_spi_set_mode(struct udevice *dev, unsigned int mode)
185 {
186 struct soft_spi_priv *priv = dev_get_priv(dev);
187
188 priv->mode = mode;
189
190 return 0;
191 }
192
193 static const struct dm_spi_ops soft_spi_ops = {
194 .claim_bus = soft_spi_claim_bus,
195 .release_bus = soft_spi_release_bus,
196 .xfer = soft_spi_xfer,
197 .set_speed = soft_spi_set_speed,
198 .set_mode = soft_spi_set_mode,
199 };
200
soft_spi_ofdata_to_platdata(struct udevice * dev)201 static int soft_spi_ofdata_to_platdata(struct udevice *dev)
202 {
203 struct soft_spi_platdata *plat = dev->platdata;
204
205 plat->spi_delay_us = dev_read_u32_default(dev, "spi-delay-us", 0);
206
207 return 0;
208 }
209
soft_spi_probe(struct udevice * dev)210 static int soft_spi_probe(struct udevice *dev)
211 {
212 struct spi_slave *slave = dev_get_parent_priv(dev);
213 struct soft_spi_platdata *plat = dev->platdata;
214 int cs_flags, clk_flags;
215 int ret;
216
217 if (slave) {
218 cs_flags = (slave->mode & SPI_CS_HIGH) ? 0 : GPIOD_ACTIVE_LOW;
219 clk_flags = (slave->mode & SPI_CPOL) ? GPIOD_ACTIVE_LOW : 0;
220 } else {
221 cs_flags = GPIOD_ACTIVE_LOW;
222 clk_flags = 0;
223 }
224
225 if (gpio_request_by_name(dev, "cs-gpios", 0, &plat->cs, GPIOD_IS_OUT | cs_flags) ||
226 (gpio_request_by_name(dev, "gpio-sck", 0, &plat->sclk, GPIOD_IS_OUT | clk_flags) &&
227 gpio_request_by_name(dev, "sck-gpios", 0, &plat->sclk, GPIOD_IS_OUT | clk_flags)))
228 return -EINVAL;
229
230 ret = gpio_request_by_name(dev, "gpio-mosi", 0, &plat->mosi,
231 GPIOD_IS_OUT | GPIOD_IS_OUT_ACTIVE);
232 if (ret) {
233 if (gpio_request_by_name(dev, "mosi-gpios", 0, &plat->mosi,
234 GPIOD_IS_OUT | GPIOD_IS_OUT_ACTIVE))
235 plat->flags |= SPI_MASTER_NO_TX;
236 }
237
238 ret = gpio_request_by_name(dev, "gpio-miso", 0, &plat->miso,
239 GPIOD_IS_IN);
240 if (ret) {
241 if (gpio_request_by_name(dev, "miso-gpios", 0, &plat->miso,
242 GPIOD_IS_IN))
243 plat->flags |= SPI_MASTER_NO_RX;
244 }
245
246 if ((plat->flags & (SPI_MASTER_NO_RX | SPI_MASTER_NO_TX)) ==
247 (SPI_MASTER_NO_RX | SPI_MASTER_NO_TX))
248 return -EINVAL;
249
250 return 0;
251 }
252
253 static const struct udevice_id soft_spi_ids[] = {
254 { .compatible = "spi-gpio" },
255 { }
256 };
257
258 U_BOOT_DRIVER(soft_spi) = {
259 .name = "soft_spi",
260 .id = UCLASS_SPI,
261 .of_match = soft_spi_ids,
262 .ops = &soft_spi_ops,
263 .ofdata_to_platdata = soft_spi_ofdata_to_platdata,
264 .platdata_auto_alloc_size = sizeof(struct soft_spi_platdata),
265 .priv_auto_alloc_size = sizeof(struct soft_spi_priv),
266 .probe = soft_spi_probe,
267 };
268