drivers/fpga/ice40-spi.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * FPGA Manager Driver for Lattice iCE40.
   4  *
   5  *  Copyright (c) 2016 Joel Holdsworth
   6  *
   7  * This driver adds support to the FPGA manager for configuring the SRAM of
   8  * Lattice iCE40 FPGAs through slave SPI.
   9  */
  10
  11 #include <linux/fpga/fpga-mgr.h>
  12 #include <linux/gpio/consumer.h>
  13 #include <linux/module.h>
  14 #include <linux/of_gpio.h>
  15 #include <linux/spi/spi.h>
  16 #include <linux/stringify.h>
  17
  18 #define ICE40_SPI_MAX_SPEED 25000000 /* Hz */
  19 #define ICE40_SPI_MIN_SPEED 1000000 /* Hz */
  20
  21 #define ICE40_SPI_RESET_DELAY 1 /* us (>200ns) */
  22 #define ICE40_SPI_HOUSEKEEPING_DELAY 1200 /* us */
  23
  24 #define ICE40_SPI_NUM_ACTIVATION_BYTES DIV_ROUND_UP(49, 8)
  25
  26 struct ice40_fpga_priv {
  27         struct spi_device *dev;
  28         struct gpio_desc *reset;
  29         struct gpio_desc *cdone;
  30 };
  31
  32 static enum fpga_mgr_states ice40_fpga_ops_state(struct fpga_manager *mgr)
  33 {
  34         struct ice40_fpga_priv *priv = mgr->priv;
  35
  36         return gpiod_get_value(priv->cdone) ? FPGA_MGR_STATE_OPERATING :
  37                 FPGA_MGR_STATE_UNKNOWN;
  38 }
  39
  40 static int ice40_fpga_ops_write_init(struct fpga_manager *mgr,
  41                                      struct fpga_image_info *info,
  42                                      const char *buf, size_t count)
  43 {
  44         struct ice40_fpga_priv *priv = mgr->priv;
  45         struct spi_device *dev = priv->dev;
  46         struct spi_message message;
  47         struct spi_transfer assert_cs_then_reset_delay = {
  48                 .cs_change   = 1,
  49                 .delay = {
  50                         .value = ICE40_SPI_RESET_DELAY,
  51                         .unit = SPI_DELAY_UNIT_USECS
  52                 }
  53         };
  54         struct spi_transfer housekeeping_delay_then_release_cs = {
  55                 .delay = {
  56                         .value = ICE40_SPI_HOUSEKEEPING_DELAY,
  57                         .unit = SPI_DELAY_UNIT_USECS
  58                 }
  59         };
  60         int ret;
  61
  62         if ((info->flags & FPGA_MGR_PARTIAL_RECONFIG)) {
  63                 dev_err(&dev->dev,
  64                         "Partial reconfiguration is not supported\n");
  65                 return -ENOTSUPP;
  66         }
  67
  68         /* Lock the bus, assert CRESET_B and SS_B and delay >200ns */
  69         spi_bus_lock(dev->master);
  70
  71         gpiod_set_value(priv->reset, 1);
  72
  73         spi_message_init(&message);
  74         spi_message_add_tail(&assert_cs_then_reset_delay, &message);
  75         ret = spi_sync_locked(dev, &message);
  76
  77         /* Come out of reset */
  78         gpiod_set_value(priv->reset, 0);
  79
  80         /* Abort if the chip-select failed */
  81         if (ret)
  82                 goto fail;
  83
  84         /* Check CDONE is de-asserted i.e. the FPGA is reset */
  85         if (gpiod_get_value(priv->cdone)) {
  86                 dev_err(&dev->dev, "Device reset failed, CDONE is asserted\n");
  87                 ret = -EIO;
  88                 goto fail;
  89         }
  90
  91         /* Wait for the housekeeping to complete, and release SS_B */
  92         spi_message_init(&message);
  93         spi_message_add_tail(&housekeeping_delay_then_release_cs, &message);
  94         ret = spi_sync_locked(dev, &message);
  95
  96 fail:
  97         spi_bus_unlock(dev->master);
  98
  99         return ret;
 100 }
 101
 102 static int ice40_fpga_ops_write(struct fpga_manager *mgr,
 103                                 const char *buf, size_t count)
 104 {
 105         struct ice40_fpga_priv *priv = mgr->priv;
 106
 107         return spi_write(priv->dev, buf, count);
 108 }
 109
 110 static int ice40_fpga_ops_write_complete(struct fpga_manager *mgr,
 111                                          struct fpga_image_info *info)
 112 {
 113         struct ice40_fpga_priv *priv = mgr->priv;
 114         struct spi_device *dev = priv->dev;
 115         const u8 padding[ICE40_SPI_NUM_ACTIVATION_BYTES] = {0};
 116
 117         /* Check CDONE is asserted */
 118         if (!gpiod_get_value(priv->cdone)) {
 119                 dev_err(&dev->dev,
 120                         "CDONE was not asserted after firmware transfer\n");
 121                 return -EIO;
 122         }
 123
 124         /* Send of zero-padding to activate the firmware */
 125         return spi_write(dev, padding, sizeof(padding));
 126 }
 127
 128 static const struct fpga_manager_ops ice40_fpga_ops = {
 129         .state = ice40_fpga_ops_state,
 130         .write_init = ice40_fpga_ops_write_init,
 131         .write = ice40_fpga_ops_write,
 132         .write_complete = ice40_fpga_ops_write_complete,
 133 };
 134
 135 static int ice40_fpga_probe(struct spi_device *spi)
 136 {
 137         struct device *dev = &spi->dev;
 138         struct ice40_fpga_priv *priv;
 139         struct fpga_manager *mgr;
 140         int ret;
 141
 142         priv = devm_kzalloc(&spi->dev, sizeof(*priv), GFP_KERNEL);
 143         if (!priv)
 144                 return -ENOMEM;
 145
 146         priv->dev = spi;
 147
 148         /* Check board setup data. */
 149         if (spi->max_speed_hz > ICE40_SPI_MAX_SPEED) {
 150                 dev_err(dev, "SPI speed is too high, maximum speed is "
 151                         __stringify(ICE40_SPI_MAX_SPEED) "\n");
 152                 return -EINVAL;
 153         }
 154
 155         if (spi->max_speed_hz < ICE40_SPI_MIN_SPEED) {
 156                 dev_err(dev, "SPI speed is too low, minimum speed is "
 157                         __stringify(ICE40_SPI_MIN_SPEED) "\n");
 158                 return -EINVAL;
 159         }
 160
 161         if (spi->mode & SPI_CPHA) {
 162                 dev_err(dev, "Bad SPI mode, CPHA not supported\n");
 163                 return -EINVAL;
 164         }
 165
 166         /* Set up the GPIOs */
 167         priv->cdone = devm_gpiod_get(dev, "cdone", GPIOD_IN);
 168         if (IS_ERR(priv->cdone)) {
 169                 ret = PTR_ERR(priv->cdone);
 170                 dev_err(dev, "Failed to get CDONE GPIO: %d\n", ret);
 171                 return ret;
 172         }
 173
 174         priv->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
 175         if (IS_ERR(priv->reset)) {
 176                 ret = PTR_ERR(priv->reset);
 177                 dev_err(dev, "Failed to get CRESET_B GPIO: %d\n", ret);
 178                 return ret;
 179         }
 180
 181         mgr = devm_fpga_mgr_create(dev, "Lattice iCE40 FPGA Manager",
 182                                    &ice40_fpga_ops, priv);
 183         if (!mgr)
 184                 return -ENOMEM;
 185
 186         return devm_fpga_mgr_register(dev, mgr);
 187 }
 188
 189 static const struct of_device_id ice40_fpga_of_match[] = {
 190         { .compatible = "lattice,ice40-fpga-mgr", },
 191         {},
 192 };
 193 MODULE_DEVICE_TABLE(of, ice40_fpga_of_match);
 194
 195 static struct spi_driver ice40_fpga_driver = {
 196         .probe = ice40_fpga_probe,
 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");