drivers/fpga/ice40-spi.c

   1 /*
   2  * FPGA Manager Driver for Lattice iCE40.
   3  *
   4  *  Copyright (c) 2016 Joel Holdsworth
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; version 2 of the License.
   9  *
  10  * This driver adds support to the FPGA manager for configuring the SRAM of
  11  * Lattice iCE40 FPGAs through slave SPI.
  12  */
  13
  14 #include <linux/fpga/fpga-mgr.h>
  15 #include <linux/gpio/consumer.h>
  16 #include <linux/module.h>
  17 #include <linux/of_gpio.h>
  18 #include <linux/spi/spi.h>
  19 #include <linux/stringify.h>
  20
  21 #define ICE40_SPI_MAX_SPEED 25000000 /* Hz */
  22 #define ICE40_SPI_MIN_SPEED 1000000 /* Hz */
  23
  24 #define ICE40_SPI_RESET_DELAY 1 /* us (>200ns) */
  25 #define ICE40_SPI_HOUSEKEEPING_DELAY 1200 /* us */
  26
  27 #define ICE40_SPI_NUM_ACTIVATION_BYTES DIV_ROUND_UP(49, 8)
  28
  29 struct ice40_fpga_priv {
  30         struct spi_device *dev;
  31         struct gpio_desc *reset;
  32         struct gpio_desc *cdone;
  33 };
  34
  35 static enum fpga_mgr_states ice40_fpga_ops_state(struct fpga_manager *mgr)
  36 {
  37         struct ice40_fpga_priv *priv = mgr->priv;
  38
  39         return gpiod_get_value(priv->cdone) ? FPGA_MGR_STATE_OPERATING :
  40                 FPGA_MGR_STATE_UNKNOWN;
  41 }
  42
  43 static int ice40_fpga_ops_write_init(struct fpga_manager *mgr,
  44                                      struct fpga_image_info *info,
  45                                      const char *buf, size_t count)
  46 {
  47         struct ice40_fpga_priv *priv = mgr->priv;
  48         struct spi_device *dev = priv->dev;
  49         struct spi_message message;
  50         struct spi_transfer assert_cs_then_reset_delay = {
  51                 .cs_change   = 1,
  52                 .delay_usecs = ICE40_SPI_RESET_DELAY
  53         };
  54         struct spi_transfer housekeeping_delay_then_release_cs = {
  55                 .delay_usecs = ICE40_SPI_HOUSEKEEPING_DELAY
  56         };
  57         int ret;
  58
  59         if ((info->flags & FPGA_MGR_PARTIAL_RECONFIG)) {
  60                 dev_err(&dev->dev,
  61                         "Partial reconfiguration is not supported\n");
  62                 return -ENOTSUPP;
  63         }
  64
  65         /* Lock the bus, assert CRESET_B and SS_B and delay >200ns */
  66         spi_bus_lock(dev->master);
  67
  68         gpiod_set_value(priv->reset, 1);
  69
  70         spi_message_init(&message);
  71         spi_message_add_tail(&assert_cs_then_reset_delay, &message);
  72         ret = spi_sync_locked(dev, &message);
  73
  74         /* Come out of reset */
  75         gpiod_set_value(priv->reset, 0);
  76
  77         /* Abort if the chip-select failed */
  78         if (ret)
  79                 goto fail;
  80
  81         /* Check CDONE is de-asserted i.e. the FPGA is reset */
  82         if (gpiod_get_value(priv->cdone)) {
  83                 dev_err(&dev->dev, "Device reset failed, CDONE is asserted\n");
  84                 ret = -EIO;
  85                 goto fail;
  86         }
  87
  88         /* Wait for the housekeeping to complete, and release SS_B */
  89         spi_message_init(&message);
  90         spi_message_add_tail(&housekeeping_delay_then_release_cs, &message);
  91         ret = spi_sync_locked(dev, &message);
  92
  93 fail:
  94         spi_bus_unlock(dev->master);
  95
  96         return ret;
  97 }
  98
  99 static int ice40_fpga_ops_write(struct fpga_manager *mgr,
 100                                 const char *buf, size_t count)
 101 {
 102         struct ice40_fpga_priv *priv = mgr->priv;
 103
 104         return spi_write(priv->dev, buf, count);
 105 }
 106
 107 static int ice40_fpga_ops_write_complete(struct fpga_manager *mgr,
 108                                          struct fpga_image_info *info)
 109 {
 110         struct ice40_fpga_priv *priv = mgr->priv;
 111         struct spi_device *dev = priv->dev;
 112         const u8 padding[ICE40_SPI_NUM_ACTIVATION_BYTES] = {0};
 113
 114         /* Check CDONE is asserted */
 115         if (!gpiod_get_value(priv->cdone)) {
 116                 dev_err(&dev->dev,
 117                         "CDONE was not asserted after firmware transfer\n");
 118                 return -EIO;
 119         }
 120
 121         /* Send of zero-padding to activate the firmware */
 122         return spi_write(dev, padding, sizeof(padding));
 123 }
 124
 125 static const struct fpga_manager_ops ice40_fpga_ops = {
 126         .state = ice40_fpga_ops_state,
 127         .write_init = ice40_fpga_ops_write_init,
 128         .write = ice40_fpga_ops_write,
 129         .write_complete = ice40_fpga_ops_write_complete,
 130 };
 131
 132 static int ice40_fpga_probe(struct spi_device *spi)
 133 {
 134         struct device *dev = &spi->dev;
 135         struct ice40_fpga_priv *priv;
 136         int ret;
 137
 138         priv = devm_kzalloc(&spi->dev, sizeof(*priv), GFP_KERNEL);
 139         if (!priv)
 140                 return -ENOMEM;
 141
 142         priv->dev = spi;
 143
 144         /* Check board setup data. */
 145         if (spi->max_speed_hz > ICE40_SPI_MAX_SPEED) {
 146                 dev_err(dev, "SPI speed is too high, maximum speed is "
 147                         __stringify(ICE40_SPI_MAX_SPEED) "\n");
 148                 return -EINVAL;
 149         }
 150
 151         if (spi->max_speed_hz < ICE40_SPI_MIN_SPEED) {
 152                 dev_err(dev, "SPI speed is too low, minimum speed is "
 153                         __stringify(ICE40_SPI_MIN_SPEED) "\n");
 154                 return -EINVAL;
 155         }
 156
 157         if (spi->mode & SPI_CPHA) {
 158                 dev_err(dev, "Bad SPI mode, CPHA not supported\n");
 159                 return -EINVAL;
 160         }
 161
 162         /* Set up the GPIOs */
 163         priv->cdone = devm_gpiod_get(dev, "cdone", GPIOD_IN);
 164         if (IS_ERR(priv->cdone)) {
 165                 ret = PTR_ERR(priv->cdone);
 166                 dev_err(dev, "Failed to get CDONE GPIO: %d\n", ret);
 167                 return ret;
 168         }
 169
 170         priv->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
 171         if (IS_ERR(priv->reset)) {
 172                 ret = PTR_ERR(priv->reset);
 173                 dev_err(dev, "Failed to get CRESET_B GPIO: %d\n", ret);
 174                 return ret;
 175         }
 176
 177         /* Register with the FPGA manager */
 178         return fpga_mgr_register(dev, "Lattice iCE40 FPGA Manager",
 179                                  &ice40_fpga_ops, priv);
 180 }
 181
 182 static int ice40_fpga_remove(struct spi_device *spi)
 183 {
 184         fpga_mgr_unregister(&spi->dev);
 185         return 0;
 186 }
 187
 188 static const struct of_device_id ice40_fpga_of_match[] = {
 189         { .compatible = "lattice,ice40-fpga-mgr", },
 190         {},
 191 };
 192 MODULE_DEVICE_TABLE(of, ice40_fpga_of_match);
 193
 194 static struct spi_driver ice40_fpga_driver = {
 195         .probe = ice40_fpga_probe,
 196         .remove = ice40_fpga_remove,
 197         .driver = {
 198                 .name = "ice40spi",
 199                 .of_match_table = of_match_ptr(ice40_fpga_of_match),
 200         },
 201 };
 202
 203 module_spi_driver(ice40_fpga_driver);
 204
 205 MODULE_AUTHOR("Joel Holdsworth <joel@airwebreathe.org.uk>");
 206 MODULE_DESCRIPTION("Lattice iCE40 FPGA Manager");
 207 MODULE_LICENSE("GPL v2");