drivers/fpga/xilinx-spi.c

   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
  26 struct xilinx_spi_conf {
  27         struct spi_device *spi;
  28         struct gpio_desc *prog_b;
  29         struct gpio_desc *done;
  30 };
  31
  32 static 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
  42 static 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
  71 static 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
  97 static 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
 110 static 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
 136 static 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
 143 static int xilinx_spi_probe(struct spi_device *spi)
 144 {
 145         struct xilinx_spi_conf *conf;
 146
 147         conf = devm_kzalloc(&spi->dev, sizeof(*conf), GFP_KERNEL);
 148         if (!conf)
 149                 return -ENOMEM;
 150
 151         conf->spi = spi;
 152
 153         /* PROGRAM_B is active low */
 154         conf->prog_b = devm_gpiod_get(&spi->dev, "prog_b", GPIOD_OUT_LOW);
 155         if (IS_ERR(conf->prog_b)) {
 156                 dev_err(&spi->dev, "Failed to get PROGRAM_B gpio: %ld\n",
 157                         PTR_ERR(conf->prog_b));
 158                 return PTR_ERR(conf->prog_b);
 159         }
 160
 161         conf->done = devm_gpiod_get(&spi->dev, "done", GPIOD_IN);
 162         if (IS_ERR(conf->done)) {
 163                 dev_err(&spi->dev, "Failed to get DONE gpio: %ld\n",
 164                         PTR_ERR(conf->done));
 165                 return PTR_ERR(conf->done);
 166         }
 167
 168         return fpga_mgr_register(&spi->dev, "Xilinx Slave Serial FPGA Manager",
 169                                  &xilinx_spi_ops, conf);
 170 }
 171
 172 static int xilinx_spi_remove(struct spi_device *spi)
 173 {
 174         fpga_mgr_unregister(&spi->dev);
 175
 176         return 0;
 177 }
 178
 179 static const struct of_device_id xlnx_spi_of_match[] = {
 180         { .compatible = "xlnx,fpga-slave-serial", },
 181         {}
 182 };
 183 MODULE_DEVICE_TABLE(of, xlnx_spi_of_match);
 184
 185 static struct spi_driver xilinx_slave_spi_driver = {
 186         .driver = {
 187                 .name = "xlnx-slave-spi",
 188                 .of_match_table = of_match_ptr(xlnx_spi_of_match),
 189         },
 190         .probe = xilinx_spi_probe,
 191         .remove = xilinx_spi_remove,
 192 };
 193
 194 module_spi_driver(xilinx_slave_spi_driver)
 195
 196 MODULE_LICENSE("GPL v2");
 197 MODULE_AUTHOR("Anatolij Gustschin <agust@denx.de>");
 198 MODULE_DESCRIPTION("Load Xilinx FPGA firmware over SPI");