summaryrefslogtreecommitdiff
path: root/drivers/fpga/xilinx-spi.c
blob: b6bcf1d9233d2b46f11942d6220b3965765823ac (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
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Xilinx Spartan6 and 7 Series Slave Serial SPI Driver
 *
 * Copyright (C) 2017 DENX Software Engineering
 *
 * Anatolij Gustschin <agust@denx.de>
 *
 * Manage Xilinx FPGA firmware that is loaded over SPI using
 * the slave serial configuration interface.
 */

#include <linux/delay.h>
#include <linux/device.h>
#include <linux/fpga/fpga-mgr.h>
#include <linux/gpio/consumer.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/of.h>
#include <linux/spi/spi.h>
#include <linux/sizes.h>

struct xilinx_spi_conf {
	struct spi_device *spi;
	struct gpio_desc *prog_b;
	struct gpio_desc *init_b;
	struct gpio_desc *done;
};

static int get_done_gpio(struct fpga_manager *mgr)
{
	struct xilinx_spi_conf *conf = mgr->priv;
	int ret;

	ret = gpiod_get_value(conf->done);

	if (ret < 0)
		dev_err(&mgr->dev, "Error reading DONE (%d)\n", ret);

	return ret;
}

static enum fpga_mgr_states xilinx_spi_state(struct fpga_manager *mgr)
{
	if (!get_done_gpio(mgr))
		return FPGA_MGR_STATE_RESET;

	return FPGA_MGR_STATE_UNKNOWN;
}

/**
 * wait_for_init_b - wait for the INIT_B pin to have a given state, or wait
 * a given delay if the pin is unavailable
 *
 * @mgr:        The FPGA manager object
 * @value:      Value INIT_B to wait for (1 = asserted = low)
 * @alt_udelay: Delay to wait if the INIT_B GPIO is not available
 *
 * Returns 0 when the INIT_B GPIO reached the given state or -ETIMEDOUT if
 * too much time passed waiting for that. If no INIT_B GPIO is available
 * then always return 0.
 */
static int wait_for_init_b(struct fpga_manager *mgr, int value,
			   unsigned long alt_udelay)
{
	struct xilinx_spi_conf *conf = mgr->priv;
	unsigned long timeout = jiffies + msecs_to_jiffies(1000);

	if (conf->init_b) {
		while (time_before(jiffies, timeout)) {
			int ret = gpiod_get_value(conf->init_b);

			if (ret == value)
				return 0;

			if (ret < 0) {
				dev_err(&mgr->dev, "Error reading INIT_B (%d)\n", ret);
				return ret;
			}

			usleep_range(100, 400);
		}

		dev_err(&mgr->dev, "Timeout waiting for INIT_B to %s\n",
			value ? "assert" : "deassert");
		return -ETIMEDOUT;
	}

	udelay(alt_udelay);

	return 0;
}

static int xilinx_spi_write_init(struct fpga_manager *mgr,
				 struct fpga_image_info *info,
				 const char *buf, size_t count)
{
	struct xilinx_spi_conf *conf = mgr->priv;
	int err;

	if (info->flags & FPGA_MGR_PARTIAL_RECONFIG) {
		dev_err(&mgr->dev, "Partial reconfiguration not supported\n");
		return -EINVAL;
	}

	gpiod_set_value(conf->prog_b, 1);

	err = wait_for_init_b(mgr, 1, 1); /* min is 500 ns */
	if (err) {
		gpiod_set_value(conf->prog_b, 0);
		return err;
	}

	gpiod_set_value(conf->prog_b, 0);

	err = wait_for_init_b(mgr, 0, 0);
	if (err)
		return err;

	if (get_done_gpio(mgr)) {
		dev_err(&mgr->dev, "Unexpected DONE pin state...\n");
		return -EIO;
	}

	/* program latency */
	usleep_range(7500, 7600);
	return 0;
}

static int xilinx_spi_write(struct fpga_manager *mgr, const char *buf,
			    size_t count)
{
	struct xilinx_spi_conf *conf = mgr->priv;
	const char *fw_data = buf;
	const char *fw_data_end = fw_data + count;

	while (fw_data < fw_data_end) {
		size_t remaining, stride;
		int ret;

		remaining = fw_data_end - fw_data;
		stride = min_t(size_t, remaining, SZ_4K);

		ret = spi_write(conf->spi, fw_data, stride);
		if (ret) {
			dev_err(&mgr->dev, "SPI error in firmware write: %d\n",
				ret);
			return ret;
		}
		fw_data += stride;
	}

	return 0;
}

static int xilinx_spi_apply_cclk_cycles(struct xilinx_spi_conf *conf)
{
	struct spi_device *spi = conf->spi;
	const u8 din_data[1] = { 0xff };
	int ret;

	ret = spi_write(conf->spi, din_data, sizeof(din_data));
	if (ret)
		dev_err(&spi->dev, "applying CCLK cycles failed: %d\n", ret);

	return ret;
}

static int xilinx_spi_write_complete(struct fpga_manager *mgr,
				     struct fpga_image_info *info)
{
	struct xilinx_spi_conf *conf = mgr->priv;
	unsigned long timeout = jiffies + usecs_to_jiffies(info->config_complete_timeout_us);
	bool expired = false;
	int done;
	int ret;

	/*
	 * This loop is carefully written such that if the driver is
	 * scheduled out for more than 'timeout', we still check for DONE
	 * before giving up and we apply 8 extra CCLK cycles in all cases.
	 */
	while (!expired) {
		expired = time_after(jiffies, timeout);

		done = get_done_gpio(mgr);
		if (done < 0)
			return done;

		ret = xilinx_spi_apply_cclk_cycles(conf);
		if (ret)
			return ret;

		if (done)
			return 0;
	}

	if (conf->init_b) {
		ret = gpiod_get_value(conf->init_b);

		if (ret < 0) {
			dev_err(&mgr->dev, "Error reading INIT_B (%d)\n", ret);
			return ret;
		}

		dev_err(&mgr->dev,
			ret ? "CRC error or invalid device\n"
			: "Missing sync word or incomplete bitstream\n");
	} else {
		dev_err(&mgr->dev, "Timeout after config data transfer\n");
	}

	return -ETIMEDOUT;
}

static const struct fpga_manager_ops xilinx_spi_ops = {
	.state = xilinx_spi_state,
	.write_init = xilinx_spi_write_init,
	.write = xilinx_spi_write,
	.write_complete = xilinx_spi_write_complete,
};

static int xilinx_spi_probe(struct spi_device *spi)
{
	struct xilinx_spi_conf *conf;
	struct fpga_manager *mgr;

	conf = devm_kzalloc(&spi->dev, sizeof(*conf), GFP_KERNEL);
	if (!conf)
		return -ENOMEM;

	conf->spi = spi;

	/* PROGRAM_B is active low */
	conf->prog_b = devm_gpiod_get(&spi->dev, "prog_b", GPIOD_OUT_LOW);
	if (IS_ERR(conf->prog_b))
		return dev_err_probe(&spi->dev, PTR_ERR(conf->prog_b),
				     "Failed to get PROGRAM_B gpio\n");

	conf->init_b = devm_gpiod_get_optional(&spi->dev, "init-b", GPIOD_IN);
	if (IS_ERR(conf->init_b))
		return dev_err_probe(&spi->dev, PTR_ERR(conf->init_b),
				     "Failed to get INIT_B gpio\n");

	conf->done = devm_gpiod_get(&spi->dev, "done", GPIOD_IN);
	if (IS_ERR(conf->done))
		return dev_err_probe(&spi->dev, PTR_ERR(conf->done),
				     "Failed to get DONE gpio\n");

	mgr = devm_fpga_mgr_create(&spi->dev,
				   "Xilinx Slave Serial FPGA Manager",
				   &xilinx_spi_ops, conf);
	if (!mgr)
		return -ENOMEM;

	return devm_fpga_mgr_register(&spi->dev, mgr);
}

#ifdef CONFIG_OF
static const struct of_device_id xlnx_spi_of_match[] = {
	{ .compatible = "xlnx,fpga-slave-serial", },
	{}
};
MODULE_DEVICE_TABLE(of, xlnx_spi_of_match);
#endif

static struct spi_driver xilinx_slave_spi_driver = {
	.driver = {
		.name = "xlnx-slave-spi",
		.of_match_table = of_match_ptr(xlnx_spi_of_match),
	},
	.probe = xilinx_spi_probe,
};

module_spi_driver(xilinx_slave_spi_driver)

MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Anatolij Gustschin <agust@denx.de>");
MODULE_DESCRIPTION("Load Xilinx FPGA firmware over SPI");