drivers/spi/soft_spi.c

   1 /*
   2  * Copyright (c) 2014 Google, Inc
   3  *
   4  * (C) Copyright 2002
   5  * Gerald Van Baren, Custom IDEAS, vanbaren@cideas.com.
   6  *
   7  * Influenced by code from:
   8  * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
   9  *
  10  * SPDX-License-Identifier:     GPL-2.0+
  11  */
  12
  13 #include <common.h>
  14 #include <dm.h>
  15 #include <errno.h>
  16 #include <fdtdec.h>
  17 #include <malloc.h>
  18 #include <spi.h>
  19 #include <asm/gpio.h>
  20
  21 DECLARE_GLOBAL_DATA_PTR;
  22
  23 struct soft_spi_platdata {
  24         struct fdt_gpio_state cs;
  25         struct fdt_gpio_state sclk;
  26         struct fdt_gpio_state mosi;
  27         struct fdt_gpio_state miso;
  28         int spi_delay_us;
  29 };
  30
  31 struct soft_spi_priv {
  32         unsigned int mode;
  33 };
  34
  35 static int soft_spi_scl(struct udevice *dev, int bit)
  36 {
  37         struct soft_spi_platdata *plat = dev->platdata;
  38         struct soft_spi_priv *priv = dev_get_priv(dev);
  39
  40         gpio_set_value(plat->sclk.gpio, priv->mode & SPI_CPOL ? bit : !bit);
  41
  42         return 0;
  43 }
  44
  45 static int soft_spi_sda(struct udevice *dev, int bit)
  46 {
  47         struct soft_spi_platdata *plat = dev->platdata;
  48
  49         gpio_set_value(plat->mosi.gpio, bit);
  50
  51         return 0;
  52 }
  53
  54 static int soft_spi_cs_activate(struct udevice *dev)
  55 {
  56         struct soft_spi_platdata *plat = dev->platdata;
  57         struct soft_spi_priv *priv = dev_get_priv(dev);
  58
  59         gpio_set_value(plat->cs.gpio, !(priv->mode & SPI_CS_HIGH));
  60         gpio_set_value(plat->sclk.gpio, priv->mode & SPI_CPOL);
  61         gpio_set_value(plat->cs.gpio, priv->mode & SPI_CS_HIGH);
  62
  63         return 0;
  64 }
  65
  66 static int soft_spi_cs_deactivate(struct udevice *dev)
  67 {
  68         struct soft_spi_platdata *plat = dev->platdata;
  69         struct soft_spi_priv *priv = dev_get_priv(dev);
  70
  71         gpio_set_value(plat->cs.gpio, !(priv->mode & SPI_CS_HIGH));
  72
  73         return 0;
  74 }
  75
  76 static int soft_spi_claim_bus(struct udevice *dev)
  77 {
  78         /*
  79          * Make sure the SPI clock is in idle state as defined for
  80          * this slave.
  81          */
  82         return soft_spi_scl(dev, 0);
  83 }
  84
  85 static int soft_spi_release_bus(struct udevice *dev)
  86 {
  87         /* Nothing to do */
  88         return 0;
  89 }
  90
  91 /*-----------------------------------------------------------------------
  92  * SPI transfer
  93  *
  94  * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks
  95  * "bitlen" bits in the SPI MISO port.  That's just the way SPI works.
  96  *
  97  * The source of the outgoing bits is the "dout" parameter and the
  98  * destination of the input bits is the "din" parameter.  Note that "dout"
  99  * and "din" can point to the same memory location, in which case the
 100  * input data overwrites the output data (since both are buffered by
 101  * temporary variables, this is OK).
 102  */
 103 static int soft_spi_xfer(struct udevice *dev, unsigned int bitlen,
 104                          const void *dout, void *din, unsigned long flags)
 105 {
 106         struct soft_spi_priv *priv = dev_get_priv(dev);
 107         struct soft_spi_platdata *plat = dev->platdata;
 108         uchar           tmpdin  = 0;
 109         uchar           tmpdout = 0;
 110         const u8        *txd = dout;
 111         u8              *rxd = din;
 112         int             cpol = priv->mode & SPI_CPOL;
 113         int             cpha = priv->mode & SPI_CPHA;
 114         unsigned int    j;
 115
 116         debug("spi_xfer: slave %s:%s dout %08X din %08X bitlen %u\n",
 117               dev->parent->name, dev->name, *(uint *)txd, *(uint *)rxd,
 118               bitlen);
 119
 120         if (flags & SPI_XFER_BEGIN)
 121                 soft_spi_cs_activate(dev);
 122
 123         for (j = 0; j < bitlen; j++) {
 124                 /*
 125                  * Check if it is time to work on a new byte.
 126                  */
 127                 if ((j % 8) == 0) {
 128                         if (txd)
 129                                 tmpdout = *txd++;
 130                         else
 131                                 tmpdout = 0;
 132                         if (j != 0) {
 133                                 if (rxd)
 134                                         *rxd++ = tmpdin;
 135                         }
 136                         tmpdin  = 0;
 137                 }
 138
 139                 if (!cpha)
 140                         soft_spi_scl(dev, !cpol);
 141                 soft_spi_sda(dev, tmpdout & 0x80);
 142                 udelay(plat->spi_delay_us);
 143                 if (cpha)
 144                         soft_spi_scl(dev, !cpol);
 145                 else
 146                         soft_spi_scl(dev, cpol);
 147                 tmpdin  <<= 1;
 148                 tmpdin  |= gpio_get_value(plat->miso.gpio);
 149                 tmpdout <<= 1;
 150                 udelay(plat->spi_delay_us);
 151                 if (cpha)
 152                         soft_spi_scl(dev, cpol);
 153         }
 154         /*
 155          * If the number of bits isn't a multiple of 8, shift the last
 156          * bits over to left-justify them.  Then store the last byte
 157          * read in.
 158          */
 159         if (rxd) {
 160                 if ((bitlen % 8) != 0)
 161                         tmpdin <<= 8 - (bitlen % 8);
 162                 *rxd++ = tmpdin;
 163         }
 164
 165         if (flags & SPI_XFER_END)
 166                 soft_spi_cs_deactivate(dev);
 167
 168         return 0;
 169 }
 170
 171 static int soft_spi_set_speed(struct udevice *dev, unsigned int speed)
 172 {
 173         /* Accept any speed */
 174         return 0;
 175 }
 176
 177 static int soft_spi_set_mode(struct udevice *dev, unsigned int mode)
 178 {
 179         struct soft_spi_priv *priv = dev_get_priv(dev);
 180
 181         priv->mode = mode;
 182
 183         return 0;
 184 }
 185
 186 static int soft_spi_child_pre_probe(struct udevice *dev)
 187 {
 188         struct spi_slave *slave = dev_get_parentdata(dev);
 189
 190         slave->dev = dev;
 191         return spi_ofdata_to_platdata(gd->fdt_blob, dev->of_offset, slave);
 192 }
 193
 194 static const struct dm_spi_ops soft_spi_ops = {
 195         .claim_bus      = soft_spi_claim_bus,
 196         .release_bus    = soft_spi_release_bus,
 197         .xfer           = soft_spi_xfer,
 198         .set_speed      = soft_spi_set_speed,
 199         .set_mode       = soft_spi_set_mode,
 200 };
 201
 202 static int soft_spi_ofdata_to_platdata(struct udevice *dev)
 203 {
 204         struct soft_spi_platdata *plat = dev->platdata;
 205         const void *blob = gd->fdt_blob;
 206         int node = dev->of_offset;
 207
 208         if (fdtdec_decode_gpio(blob, node, "cs-gpio", &plat->cs) ||
 209             fdtdec_decode_gpio(blob, node, "sclk-gpio", &plat->sclk) ||
 210             fdtdec_decode_gpio(blob, node, "mosi-gpio", &plat->mosi) ||
 211             fdtdec_decode_gpio(blob, node, "miso-gpio", &plat->miso))
 212                 return -EINVAL;
 213         plat->spi_delay_us = fdtdec_get_int(blob, node, "spi-delay-us", 0);
 214
 215         return 0;
 216 }
 217
 218 static int soft_spi_probe(struct udevice *dev)
 219 {
 220         struct spi_slave *slave = dev_get_parentdata(dev);
 221         struct soft_spi_platdata *plat = dev->platdata;
 222
 223         gpio_request(plat->cs.gpio, "soft_spi_cs");
 224         gpio_request(plat->sclk.gpio, "soft_spi_sclk");
 225         gpio_request(plat->mosi.gpio, "soft_spi_mosi");
 226         gpio_request(plat->miso.gpio, "soft_spi_miso");
 227
 228         gpio_direction_output(plat->sclk.gpio, slave->mode & SPI_CPOL);
 229         gpio_direction_output(plat->mosi.gpio, 1);
 230         gpio_direction_input(plat->miso.gpio);
 231         gpio_direction_output(plat->cs.gpio, !(slave->mode & SPI_CS_HIGH));
 232
 233         return 0;
 234 }
 235
 236 static const struct udevice_id soft_spi_ids[] = {
 237         { .compatible = "u-boot,soft-spi" },
 238         { }
 239 };
 240
 241 U_BOOT_DRIVER(soft_spi) = {
 242         .name   = "soft_spi",
 243         .id     = UCLASS_SPI,
 244         .of_match = soft_spi_ids,
 245         .ops    = &soft_spi_ops,
 246         .ofdata_to_platdata = soft_spi_ofdata_to_platdata,
 247         .platdata_auto_alloc_size = sizeof(struct soft_spi_platdata),
 248         .priv_auto_alloc_size = sizeof(struct soft_spi_priv),
 249         .per_child_auto_alloc_size      = sizeof(struct spi_slave),
 250         .probe  = soft_spi_probe,
 251         .child_pre_probe        = soft_spi_child_pre_probe,
 252 };