summaryrefslogtreecommitdiff
path: root/drivers/spi/soft_spi.c
blob: 153bbf8b2557e8d7d72cd013948da2093554ea8b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright (c) 2014 Google, Inc
 *
 * (C) Copyright 2002
 * Gerald Van Baren, Custom IDEAS, vanbaren@cideas.com.
 *
 * Influenced by code from:
 * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
 */

#include <common.h>
#include <dm.h>
#include <errno.h>
#include <fdtdec.h>
#include <log.h>
#include <malloc.h>
#include <spi.h>
#include <asm/gpio.h>
#include <linux/bitops.h>
#include <linux/delay.h>

DECLARE_GLOBAL_DATA_PTR;

struct soft_spi_platdata {
	struct gpio_desc cs;
	struct gpio_desc sclk;
	struct gpio_desc mosi;
	struct gpio_desc miso;
	int spi_delay_us;
	int flags;
};

#define SPI_MASTER_NO_RX        BIT(0)
#define SPI_MASTER_NO_TX        BIT(1)

struct soft_spi_priv {
	unsigned int mode;
};

static int soft_spi_scl(struct udevice *dev, int bit)
{
	struct udevice *bus = dev_get_parent(dev);
	struct soft_spi_platdata *plat = dev_get_platdata(bus);

	dm_gpio_set_value(&plat->sclk, bit);

	return 0;
}

static int soft_spi_sda(struct udevice *dev, int bit)
{
	struct udevice *bus = dev_get_parent(dev);
	struct soft_spi_platdata *plat = dev_get_platdata(bus);

	dm_gpio_set_value(&plat->mosi, bit);

	return 0;
}

static int soft_spi_cs_activate(struct udevice *dev)
{
	struct udevice *bus = dev_get_parent(dev);
	struct soft_spi_priv *priv = dev_get_priv(bus);
	struct soft_spi_platdata *plat = dev_get_platdata(bus);
	int cidle = !!(priv->mode & SPI_CPOL);

	dm_gpio_set_value(&plat->cs, 0);
	dm_gpio_set_value(&plat->sclk, cidle); /* to idle */
	dm_gpio_set_value(&plat->cs, 1);

	return 0;
}

static int soft_spi_cs_deactivate(struct udevice *dev)
{
	struct udevice *bus = dev_get_parent(dev);
	struct soft_spi_platdata *plat = dev_get_platdata(bus);

	dm_gpio_set_value(&plat->cs, 0);

	return 0;
}

static int soft_spi_claim_bus(struct udevice *dev)
{
	struct udevice *bus = dev_get_parent(dev);
	struct soft_spi_priv *priv = dev_get_priv(bus);
	int cidle = !!(priv->mode & SPI_CPOL);
	/*
	 * Make sure the SPI clock is in idle state as defined for
	 * this slave.
	 */
	return soft_spi_scl(dev, cidle);
}

static int soft_spi_release_bus(struct udevice *dev)
{
	/* Nothing to do */
	return 0;
}

/*-----------------------------------------------------------------------
 * SPI transfer
 *
 * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks
 * "bitlen" bits in the SPI MISO port.  That's just the way SPI works.
 *
 * The source of the outgoing bits is the "dout" parameter and the
 * destination of the input bits is the "din" parameter.  Note that "dout"
 * and "din" can point to the same memory location, in which case the
 * input data overwrites the output data (since both are buffered by
 * temporary variables, this is OK).
 */
static int soft_spi_xfer(struct udevice *dev, unsigned int bitlen,
			 const void *dout, void *din, unsigned long flags)
{
	struct udevice *bus = dev_get_parent(dev);
	struct soft_spi_priv *priv = dev_get_priv(bus);
	struct soft_spi_platdata *plat = dev_get_platdata(bus);
	uchar		tmpdin  = 0;
	uchar		tmpdout = 0;
	const u8	*txd = dout;
	u8		*rxd = din;
	int		cpha = !!(priv->mode & SPI_CPHA);
	int		cidle = !!(priv->mode & SPI_CPOL);
	unsigned int	j;

	debug("spi_xfer: slave %s:%s dout %08X din %08X bitlen %u\n",
	      dev->parent->name, dev->name, *(uint *)txd, *(uint *)rxd,
	      bitlen);

	if (flags & SPI_XFER_BEGIN)
		soft_spi_cs_activate(dev);

	for (j = 0; j < bitlen; j++) {
		/*
		 * Check if it is time to work on a new byte.
		 */
		if ((j % 8) == 0) {
			if (txd)
				tmpdout = *txd++;
			else
				tmpdout = 0;
			if (j != 0) {
				if (rxd)
					*rxd++ = tmpdin;
			}
			tmpdin  = 0;
		}

		/*
		 * CPOL 0: idle is low (0), active is high (1)
		 * CPOL 1: idle is high (1), active is low (0)
		 */

		/*
		 * drive bit
		 *  CPHA 1: CLK from idle to active
		 */
		if (cpha)
			soft_spi_scl(dev, !cidle);
		if ((plat->flags & SPI_MASTER_NO_TX) == 0)
			soft_spi_sda(dev, !!(tmpdout & 0x80));
		udelay(plat->spi_delay_us);

		/*
		 * sample bit
		 *  CPHA 0: CLK from idle to active
		 *  CPHA 1: CLK from active to idle
		 */
		if (!cpha)
			soft_spi_scl(dev, !cidle);
		else
			soft_spi_scl(dev, cidle);
		tmpdin	<<= 1;
		if ((plat->flags & SPI_MASTER_NO_RX) == 0)
			tmpdin	|= dm_gpio_get_value(&plat->miso);
		tmpdout	<<= 1;
		udelay(plat->spi_delay_us);

		/*
		 * drive bit
		 *  CPHA 0: CLK from active to idle
		 */
		if (!cpha)
			soft_spi_scl(dev, cidle);
	}
	/*
	 * If the number of bits isn't a multiple of 8, shift the last
	 * bits over to left-justify them.  Then store the last byte
	 * read in.
	 */
	if (rxd) {
		if ((bitlen % 8) != 0)
			tmpdin <<= 8 - (bitlen % 8);
		*rxd++ = tmpdin;
	}

	if (flags & SPI_XFER_END)
		soft_spi_cs_deactivate(dev);

	return 0;
}

static int soft_spi_set_speed(struct udevice *dev, unsigned int speed)
{
	/* Ignore any speed settings. Speed is implemented via "spi-delay-us" */
	return 0;
}

static int soft_spi_set_mode(struct udevice *dev, unsigned int mode)
{
	struct soft_spi_priv *priv = dev_get_priv(dev);

	priv->mode = mode;

	return 0;
}

static const struct dm_spi_ops soft_spi_ops = {
	.claim_bus	= soft_spi_claim_bus,
	.release_bus	= soft_spi_release_bus,
	.xfer		= soft_spi_xfer,
	.set_speed	= soft_spi_set_speed,
	.set_mode	= soft_spi_set_mode,
};

static int soft_spi_ofdata_to_platdata(struct udevice *dev)
{
	struct soft_spi_platdata *plat = dev->platdata;
	const void *blob = gd->fdt_blob;
	int node = dev_of_offset(dev);

	plat->spi_delay_us = fdtdec_get_int(blob, node, "spi-delay-us", 0);

	return 0;
}

static int soft_spi_probe(struct udevice *dev)
{
	struct spi_slave *slave = dev_get_parent_priv(dev);
	struct soft_spi_platdata *plat = dev->platdata;
	int cs_flags, clk_flags;
	int ret;

	cs_flags = (slave && slave->mode & SPI_CS_HIGH) ? 0 : GPIOD_ACTIVE_LOW;
	clk_flags = (slave && slave->mode & SPI_CPOL) ? GPIOD_ACTIVE_LOW : 0;

	if (gpio_request_by_name(dev, "cs-gpios", 0, &plat->cs,
				 GPIOD_IS_OUT | cs_flags) ||
	    gpio_request_by_name(dev, "gpio-sck", 0, &plat->sclk,
				 GPIOD_IS_OUT | clk_flags))
		return -EINVAL;

	ret = gpio_request_by_name(dev, "gpio-mosi", 0, &plat->mosi,
				   GPIOD_IS_OUT | GPIOD_IS_OUT_ACTIVE);
	if (ret)
		plat->flags |= SPI_MASTER_NO_TX;

	ret = gpio_request_by_name(dev, "gpio-miso", 0, &plat->miso,
				   GPIOD_IS_IN);
	if (ret)
		plat->flags |= SPI_MASTER_NO_RX;

	if ((plat->flags & (SPI_MASTER_NO_RX | SPI_MASTER_NO_TX)) ==
	    (SPI_MASTER_NO_RX | SPI_MASTER_NO_TX))
		return -EINVAL;

	return 0;
}

static const struct udevice_id soft_spi_ids[] = {
	{ .compatible = "spi-gpio" },
	{ }
};

U_BOOT_DRIVER(soft_spi) = {
	.name	= "soft_spi",
	.id	= UCLASS_SPI,
	.of_match = soft_spi_ids,
	.ops	= &soft_spi_ops,
	.ofdata_to_platdata = soft_spi_ofdata_to_platdata,
	.platdata_auto_alloc_size = sizeof(struct soft_spi_platdata),
	.priv_auto_alloc_size = sizeof(struct soft_spi_priv),
	.probe	= soft_spi_probe,
};