drivers/fpga/xilinx-spi.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Xilinx Spartan6 Slave Serial SPI Driver
   4  *
   5  * Copyright (C) 2017 DENX Software Engineering
   6  *
   7  * Anatolij Gustschin <agust@denx.de>
   8  *
   9  * Manage Xilinx FPGA firmware that is loaded over SPI using
  10  * the slave serial configuration interface.
  11  */
  12
  13 #include <linux/delay.h>
  14 #include <linux/device.h>
  15 #include <linux/fpga/fpga-mgr.h>
  16 #include <linux/gpio/consumer.h>
  17 #include <linux/module.h>
  18 #include <linux/mod_devicetable.h>
  19 #include <linux/of.h>
  20 #include <linux/spi/spi.h>
  21 #include <linux/sizes.h>
  22
  23 struct xilinx_spi_conf {
  24         struct spi_device *spi;
  25         struct gpio_desc *prog_b;
  26         struct gpio_desc *done;
  27 };
  28
  29 static enum fpga_mgr_states xilinx_spi_state(struct fpga_manager *mgr)
  30 {
  31         struct xilinx_spi_conf *conf = mgr->priv;
  32
  33         if (!gpiod_get_value(conf->done))
  34                 return FPGA_MGR_STATE_RESET;
  35
  36         return FPGA_MGR_STATE_UNKNOWN;
  37 }
  38
  39 static int xilinx_spi_write_init(struct fpga_manager *mgr,
  40                                  struct fpga_image_info *info,
  41                                  const char *buf, size_t count)
  42 {
  43         struct xilinx_spi_conf *conf = mgr->priv;
  44         const size_t prog_latency_7500us = 7500;
  45         const size_t prog_pulse_1us = 1;
  46
  47         if (info->flags & FPGA_MGR_PARTIAL_RECONFIG) {
  48                 dev_err(&mgr->dev, "Partial reconfiguration not supported.\n");
  49                 return -EINVAL;
  50         }
  51
  52         gpiod_set_value(conf->prog_b, 1);
  53
  54         udelay(prog_pulse_1us); /* min is 500 ns */
  55
  56         gpiod_set_value(conf->prog_b, 0);
  57
  58         if (gpiod_get_value(conf->done)) {
  59                 dev_err(&mgr->dev, "Unexpected DONE pin state...\n");
  60                 return -EIO;
  61         }
  62
  63         /* program latency */
  64         usleep_range(prog_latency_7500us, prog_latency_7500us + 100);
  65         return 0;
  66 }
  67
  68 static int xilinx_spi_write(struct fpga_manager *mgr, const char *buf,
  69                             size_t count)
  70 {
  71         struct xilinx_spi_conf *conf = mgr->priv;
  72         const char *fw_data = buf;
  73         const char *fw_data_end = fw_data + count;
  74
  75         while (fw_data < fw_data_end) {
  76                 size_t remaining, stride;
  77                 int ret;
  78
  79                 remaining = fw_data_end - fw_data;
  80                 stride = min_t(size_t, remaining, SZ_4K);
  81
  82                 ret = spi_write(conf->spi, fw_data, stride);
  83                 if (ret) {
  84                         dev_err(&mgr->dev, "SPI error in firmware write: %d\n",
  85                                 ret);
  86                         return ret;
  87                 }
  88                 fw_data += stride;
  89         }
  90
  91         return 0;
  92 }
  93
  94 static int xilinx_spi_apply_cclk_cycles(struct xilinx_spi_conf *conf)
  95 {
  96         struct spi_device *spi = conf->spi;
  97         const u8 din_data[1] = { 0xff };
  98         int ret;
  99
 100         ret = spi_write(conf->spi, din_data, sizeof(din_data));
 101         if (ret)
 102                 dev_err(&spi->dev, "applying CCLK cycles failed: %d\n", ret);
 103
 104         return ret;
 105 }
 106
 107 static int xilinx_spi_write_complete(struct fpga_manager *mgr,
 108                                      struct fpga_image_info *info)
 109 {
 110         struct xilinx_spi_conf *conf = mgr->priv;
 111         unsigned long timeout;
 112         int ret;
 113
 114         if (gpiod_get_value(conf->done))
 115                 return xilinx_spi_apply_cclk_cycles(conf);
 116
 117         timeout = jiffies + usecs_to_jiffies(info->config_complete_timeout_us);
 118
 119         while (time_before(jiffies, timeout)) {
 120
 121                 ret = xilinx_spi_apply_cclk_cycles(conf);
 122                 if (ret)
 123                         return ret;
 124
 125                 if (gpiod_get_value(conf->done))
 126                         return xilinx_spi_apply_cclk_cycles(conf);
 127         }
 128
 129         dev_err(&mgr->dev, "Timeout after config data transfer.\n");
 130         return -ETIMEDOUT;
 131 }
 132
 133 static const struct fpga_manager_ops xilinx_spi_ops = {
 134         .state = xilinx_spi_state,
 135         .write_init = xilinx_spi_write_init,
 136         .write = xilinx_spi_write,
 137         .write_complete = xilinx_spi_write_complete,
 138 };
 139
 140 static int xilinx_spi_probe(struct spi_device *spi)
 141 {
 142         struct xilinx_spi_conf *conf;
 143         struct fpga_manager *mgr;
 144
 145         conf = devm_kzalloc(&spi->dev, sizeof(*conf), GFP_KERNEL);
 146         if (!conf)
 147                 return -ENOMEM;
 148
 149         conf->spi = spi;
 150
 151         /* PROGRAM_B is active low */
 152         conf->prog_b = devm_gpiod_get(&spi->dev, "prog_b", GPIOD_OUT_LOW);
 153         if (IS_ERR(conf->prog_b)) {
 154                 dev_err(&spi->dev, "Failed to get PROGRAM_B gpio: %ld\n",
 155                         PTR_ERR(conf->prog_b));
 156                 return PTR_ERR(conf->prog_b);
 157         }
 158
 159         conf->done = devm_gpiod_get(&spi->dev, "done", GPIOD_IN);
 160         if (IS_ERR(conf->done)) {
 161                 dev_err(&spi->dev, "Failed to get DONE gpio: %ld\n",
 162                         PTR_ERR(conf->done));
 163                 return PTR_ERR(conf->done);
 164         }
 165
 166         mgr = devm_fpga_mgr_create(&spi->dev,
 167                                    "Xilinx Slave Serial FPGA Manager",
 168                                    &xilinx_spi_ops, conf);
 169         if (!mgr)
 170                 return -ENOMEM;
 171
 172         spi_set_drvdata(spi, mgr);
 173
 174         return fpga_mgr_register(mgr);
 175 }
 176
 177 static int xilinx_spi_remove(struct spi_device *spi)
 178 {
 179         struct fpga_manager *mgr = spi_get_drvdata(spi);
 180
 181         fpga_mgr_unregister(mgr);
 182
 183         return 0;
 184 }
 185
 186 static const struct of_device_id xlnx_spi_of_match[] = {
 187         { .compatible = "xlnx,fpga-slave-serial", },
 188         {}
 189 };
 190 MODULE_DEVICE_TABLE(of, xlnx_spi_of_match);
 191
 192 static struct spi_driver xilinx_slave_spi_driver = {
 193         .driver = {
 194                 .name = "xlnx-slave-spi",
 195                 .of_match_table = of_match_ptr(xlnx_spi_of_match),
 196         },
 197         .probe = xilinx_spi_probe,
 198         .remove = xilinx_spi_remove,
 199 };
 200
 201 module_spi_driver(xilinx_slave_spi_driver)
 202
 203 MODULE_LICENSE("GPL v2");
 204 MODULE_AUTHOR("Anatolij Gustschin <agust@denx.de>");
 205 MODULE_DESCRIPTION("Load Xilinx FPGA firmware over SPI");