1/*
2 * Xilinx Spartan6 Slave Serial SPI Driver
3 *
4 * Copyright (C) 2017 DENX Software Engineering
5 *
6 * Anatolij Gustschin <agust@denx.de>
7 *
8 * This program is free software; you can redistribute it and/or modify it
9 * under the terms and conditions of the GNU General Public License,
10 * version 2, as published by the Free Software Foundation.
11 *
12 * Manage Xilinx FPGA firmware that is loaded over SPI using
13 * the slave serial configuration interface.
14 */
15
16#include <linux/delay.h>
17#include <linux/device.h>
18#include <linux/fpga/fpga-mgr.h>
19#include <linux/gpio/consumer.h>
20#include <linux/module.h>
21#include <linux/mod_devicetable.h>
22#include <linux/of.h>
23#include <linux/spi/spi.h>
24#include <linux/sizes.h>
25
26struct xilinx_spi_conf {
27 struct spi_device *spi;
28 struct gpio_desc *prog_b;
29 struct gpio_desc *done;
30};
31
32static enum fpga_mgr_states xilinx_spi_state(struct fpga_manager *mgr)
33{
34 struct xilinx_spi_conf *conf = mgr->priv;
35
36 if (!gpiod_get_value(conf->done))
37 return FPGA_MGR_STATE_RESET;
38
39 return FPGA_MGR_STATE_UNKNOWN;
40}
41
42static int xilinx_spi_write_init(struct fpga_manager *mgr,
43 struct fpga_image_info *info,
44 const char *buf, size_t count)
45{
46 struct xilinx_spi_conf *conf = mgr->priv;
47 const size_t prog_latency_7500us = 7500;
48 const size_t prog_pulse_1us = 1;
49
50 if (info->flags & FPGA_MGR_PARTIAL_RECONFIG) {
51 dev_err(&mgr->dev, "Partial reconfiguration not supported.\n");
52 return -EINVAL;
53 }
54
55 gpiod_set_value(conf->prog_b, 1);
56
57 udelay(prog_pulse_1us); /* min is 500 ns */
58
59 gpiod_set_value(conf->prog_b, 0);
60
61 if (gpiod_get_value(conf->done)) {
62 dev_err(&mgr->dev, "Unexpected DONE pin state...\n");
63 return -EIO;
64 }
65
66 /* program latency */
67 usleep_range(prog_latency_7500us, prog_latency_7500us + 100);
68 return 0;
69}
70
71static int xilinx_spi_write(struct fpga_manager *mgr, const char *buf,
72 size_t count)
73{
74 struct xilinx_spi_conf *conf = mgr->priv;
75 const char *fw_data = buf;
76 const char *fw_data_end = fw_data + count;
77
78 while (fw_data < fw_data_end) {
79 size_t remaining, stride;
80 int ret;
81
82 remaining = fw_data_end - fw_data;
83 stride = min_t(size_t, remaining, SZ_4K);
84
85 ret = spi_write(conf->spi, fw_data, stride);
86 if (ret) {
87 dev_err(&mgr->dev, "SPI error in firmware write: %d\n",
88 ret);
89 return ret;
90 }
91 fw_data += stride;
92 }
93
94 return 0;
95}
96
97static int xilinx_spi_apply_cclk_cycles(struct xilinx_spi_conf *conf)
98{
99 struct spi_device *spi = conf->spi;
100 const u8 din_data[1] = { 0xff };
101 int ret;
102
103 ret = spi_write(conf->spi, din_data, sizeof(din_data));
104 if (ret)
105 dev_err(&spi->dev, "applying CCLK cycles failed: %d\n", ret);
106
107 return ret;
108}
109
110static int xilinx_spi_write_complete(struct fpga_manager *mgr,
111 struct fpga_image_info *info)
112{
113 struct xilinx_spi_conf *conf = mgr->priv;
114 unsigned long timeout;
115 int ret;
116
117 if (gpiod_get_value(conf->done))
118 return xilinx_spi_apply_cclk_cycles(conf);
119
120 timeout = jiffies + usecs_to_jiffies(info->config_complete_timeout_us);
121
122 while (time_before(jiffies, timeout)) {
123
124 ret = xilinx_spi_apply_cclk_cycles(conf);
125 if (ret)
126 return ret;
127
128 if (gpiod_get_value(conf->done))
129 return xilinx_spi_apply_cclk_cycles(conf);
130 }
131
132 dev_err(&mgr->dev, "Timeout after config data transfer.\n");
133 return -ETIMEDOUT;
134}
135
136static const struct fpga_manager_ops xilinx_spi_ops = {
137 .state = xilinx_spi_state,
138 .write_init = xilinx_spi_write_init,
139 .write = xilinx_spi_write,
140 .write_complete = xilinx_spi_write_complete,
141};
142
143static int xilinx_spi_probe(struct spi_device *spi)
144{
145 struct xilinx_spi_conf *conf;
146 struct fpga_manager *mgr;
147
148 conf = devm_kzalloc(&spi->dev, sizeof(*conf), GFP_KERNEL);
149 if (!conf)
150 return -ENOMEM;
151
152 conf->spi = spi;
153
154 /* PROGRAM_B is active low */
155 conf->prog_b = devm_gpiod_get(&spi->dev, "prog_b", GPIOD_OUT_LOW);
156 if (IS_ERR(conf->prog_b)) {
157 dev_err(&spi->dev, "Failed to get PROGRAM_B gpio: %ld\n",
158 PTR_ERR(conf->prog_b));
159 return PTR_ERR(conf->prog_b);
160 }
161
162 conf->done = devm_gpiod_get(&spi->dev, "done", GPIOD_IN);
163 if (IS_ERR(conf->done)) {
164 dev_err(&spi->dev, "Failed to get DONE gpio: %ld\n",
165 PTR_ERR(conf->done));
166 return PTR_ERR(conf->done);
167 }
168
169 mgr = devm_fpga_mgr_create(&spi->dev,
170 "Xilinx Slave Serial FPGA Manager",
171 &xilinx_spi_ops, conf);
172 if (!mgr)
173 return -ENOMEM;
174
175 spi_set_drvdata(spi, mgr);
176
177 return fpga_mgr_register(mgr);
178}
179
180static int xilinx_spi_remove(struct spi_device *spi)
181{
182 struct fpga_manager *mgr = spi_get_drvdata(spi);
183
184 fpga_mgr_unregister(mgr);
185
186 return 0;
187}
188
189static const struct of_device_id xlnx_spi_of_match[] = {
190 { .compatible = "xlnx,fpga-slave-serial", },
191 {}
192};
193MODULE_DEVICE_TABLE(of, xlnx_spi_of_match);
194
195static struct spi_driver xilinx_slave_spi_driver = {
196 .driver = {
197 .name = "xlnx-slave-spi",
198 .of_match_table = of_match_ptr(xlnx_spi_of_match),
199 },
200 .probe = xilinx_spi_probe,
201 .remove = xilinx_spi_remove,
202};
203
204module_spi_driver(xilinx_slave_spi_driver)
205
206MODULE_LICENSE("GPL v2");
207MODULE_AUTHOR("Anatolij Gustschin <agust@denx.de>");
208MODULE_DESCRIPTION("Load Xilinx FPGA firmware over SPI");
209