drivers/spi/spi-bcm53xx.c

   1 /*
   2  * Copyright (C) 2014-2016 Rafał Miłecki <rafal@milecki.pl>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  */
   8
   9 #define pr_fmt(fmt)             KBUILD_MODNAME ": " fmt
  10
  11 #include <linux/kernel.h>
  12 #include <linux/module.h>
  13 #include <linux/slab.h>
  14 #include <linux/delay.h>
  15 #include <linux/bcma/bcma.h>
  16 #include <linux/spi/spi.h>
  17
  18 #include "spi-bcm53xx.h"
  19
  20 #define BCM53XXSPI_MAX_SPI_BAUD 13500000        /* 216 MHz? */
  21 #define BCM53XXSPI_FLASH_WINDOW SZ_32M
  22
  23 /* The longest observed required wait was 19 ms */
  24 #define BCM53XXSPI_SPE_TIMEOUT_MS       80
  25
  26 struct bcm53xxspi {
  27         struct bcma_device *core;
  28         struct spi_master *master;
  29         void __iomem *mmio_base;
  30
  31         size_t read_offset;
  32         bool bspi;                              /* Boot SPI mode with memory mapping */
  33 };
  34
  35 static inline u32 bcm53xxspi_read(struct bcm53xxspi *b53spi, u16 offset)
  36 {
  37         return bcma_read32(b53spi->core, offset);
  38 }
  39
  40 static inline void bcm53xxspi_write(struct bcm53xxspi *b53spi, u16 offset,
  41                                     u32 value)
  42 {
  43         bcma_write32(b53spi->core, offset, value);
  44 }
  45
  46 static void bcm53xxspi_disable_bspi(struct bcm53xxspi *b53spi)
  47 {
  48         struct device *dev = &b53spi->core->dev;
  49         unsigned long deadline;
  50         u32 tmp;
  51
  52         if (!b53spi->bspi)
  53                 return;
  54
  55         tmp = bcm53xxspi_read(b53spi, B53SPI_BSPI_MAST_N_BOOT_CTRL);
  56         if (tmp & 0x1)
  57                 return;
  58
  59         deadline = jiffies + usecs_to_jiffies(200);
  60         do {
  61                 tmp = bcm53xxspi_read(b53spi, B53SPI_BSPI_BUSY_STATUS);
  62                 if (!(tmp & 0x1)) {
  63                         bcm53xxspi_write(b53spi, B53SPI_BSPI_MAST_N_BOOT_CTRL,
  64                                          0x1);
  65                         ndelay(200);
  66                         b53spi->bspi = false;
  67                         return;
  68                 }
  69                 udelay(1);
  70         } while (!time_after_eq(jiffies, deadline));
  71
  72         dev_warn(dev, "Timeout disabling BSPI\n");
  73 }
  74
  75 static void bcm53xxspi_enable_bspi(struct bcm53xxspi *b53spi)
  76 {
  77         u32 tmp;
  78
  79         if (b53spi->bspi)
  80                 return;
  81
  82         tmp = bcm53xxspi_read(b53spi, B53SPI_BSPI_MAST_N_BOOT_CTRL);
  83         if (!(tmp & 0x1))
  84                 return;
  85
  86         bcm53xxspi_write(b53spi, B53SPI_BSPI_MAST_N_BOOT_CTRL, 0x0);
  87         b53spi->bspi = true;
  88 }
  89
  90 static inline unsigned int bcm53xxspi_calc_timeout(size_t len)
  91 {
  92         /* Do some magic calculation based on length and buad. Add 10% and 1. */
  93         return (len * 9000 / BCM53XXSPI_MAX_SPI_BAUD * 110 / 100) + 1;
  94 }
  95
  96 static int bcm53xxspi_wait(struct bcm53xxspi *b53spi, unsigned int timeout_ms)
  97 {
  98         unsigned long deadline;
  99         u32 tmp;
 100
 101         /* SPE bit has to be 0 before we read MSPI STATUS */
 102         deadline = jiffies + msecs_to_jiffies(BCM53XXSPI_SPE_TIMEOUT_MS);
 103         do {
 104                 tmp = bcm53xxspi_read(b53spi, B53SPI_MSPI_SPCR2);
 105                 if (!(tmp & B53SPI_MSPI_SPCR2_SPE))
 106                         break;
 107                 udelay(5);
 108         } while (!time_after_eq(jiffies, deadline));
 109
 110         if (tmp & B53SPI_MSPI_SPCR2_SPE)
 111                 goto spi_timeout;
 112
 113         /* Check status */
 114         deadline = jiffies + msecs_to_jiffies(timeout_ms);
 115         do {
 116                 tmp = bcm53xxspi_read(b53spi, B53SPI_MSPI_MSPI_STATUS);
 117                 if (tmp & B53SPI_MSPI_MSPI_STATUS_SPIF) {
 118                         bcm53xxspi_write(b53spi, B53SPI_MSPI_MSPI_STATUS, 0);
 119                         return 0;
 120                 }
 121
 122                 cpu_relax();
 123                 udelay(100);
 124         } while (!time_after_eq(jiffies, deadline));
 125
 126 spi_timeout:
 127         bcm53xxspi_write(b53spi, B53SPI_MSPI_MSPI_STATUS, 0);
 128
 129         pr_err("Timeout waiting for SPI to be ready!\n");
 130
 131         return -EBUSY;
 132 }
 133
 134 static void bcm53xxspi_buf_write(struct bcm53xxspi *b53spi, u8 *w_buf,
 135                                  size_t len, bool cont)
 136 {
 137         u32 tmp;
 138         int i;
 139
 140         for (i = 0; i < len; i++) {
 141                 /* Transmit Register File MSB */
 142                 bcm53xxspi_write(b53spi, B53SPI_MSPI_TXRAM + 4 * (i * 2),
 143                                  (unsigned int)w_buf[i]);
 144         }
 145
 146         for (i = 0; i < len; i++) {
 147                 tmp = B53SPI_CDRAM_CONT | B53SPI_CDRAM_PCS_DISABLE_ALL |
 148                       B53SPI_CDRAM_PCS_DSCK;
 149                 if (!cont && i == len - 1)
 150                         tmp &= ~B53SPI_CDRAM_CONT;
 151                 tmp &= ~0x1;
 152                 /* Command Register File */
 153                 bcm53xxspi_write(b53spi, B53SPI_MSPI_CDRAM + 4 * i, tmp);
 154         }
 155
 156         /* Set queue pointers */
 157         bcm53xxspi_write(b53spi, B53SPI_MSPI_NEWQP, 0);
 158         bcm53xxspi_write(b53spi, B53SPI_MSPI_ENDQP, len - 1);
 159
 160         if (cont)
 161                 bcm53xxspi_write(b53spi, B53SPI_MSPI_WRITE_LOCK, 1);
 162
 163         /* Start SPI transfer */
 164         tmp = bcm53xxspi_read(b53spi, B53SPI_MSPI_SPCR2);
 165         tmp |= B53SPI_MSPI_SPCR2_SPE;
 166         if (cont)
 167                 tmp |= B53SPI_MSPI_SPCR2_CONT_AFTER_CMD;
 168         bcm53xxspi_write(b53spi, B53SPI_MSPI_SPCR2, tmp);
 169
 170         /* Wait for SPI to finish */
 171         bcm53xxspi_wait(b53spi, bcm53xxspi_calc_timeout(len));
 172
 173         if (!cont)
 174                 bcm53xxspi_write(b53spi, B53SPI_MSPI_WRITE_LOCK, 0);
 175
 176         b53spi->read_offset = len;
 177 }
 178
 179 static void bcm53xxspi_buf_read(struct bcm53xxspi *b53spi, u8 *r_buf,
 180                                 size_t len, bool cont)
 181 {
 182         u32 tmp;
 183         int i;
 184
 185         for (i = 0; i < b53spi->read_offset + len; i++) {
 186                 tmp = B53SPI_CDRAM_CONT | B53SPI_CDRAM_PCS_DISABLE_ALL |
 187                       B53SPI_CDRAM_PCS_DSCK;
 188                 if (!cont && i == b53spi->read_offset + len - 1)
 189                         tmp &= ~B53SPI_CDRAM_CONT;
 190                 tmp &= ~0x1;
 191                 /* Command Register File */
 192                 bcm53xxspi_write(b53spi, B53SPI_MSPI_CDRAM + 4 * i, tmp);
 193         }
 194
 195         /* Set queue pointers */
 196         bcm53xxspi_write(b53spi, B53SPI_MSPI_NEWQP, 0);
 197         bcm53xxspi_write(b53spi, B53SPI_MSPI_ENDQP,
 198                          b53spi->read_offset + len - 1);
 199
 200         if (cont)
 201                 bcm53xxspi_write(b53spi, B53SPI_MSPI_WRITE_LOCK, 1);
 202
 203         /* Start SPI transfer */
 204         tmp = bcm53xxspi_read(b53spi, B53SPI_MSPI_SPCR2);
 205         tmp |= B53SPI_MSPI_SPCR2_SPE;
 206         if (cont)
 207                 tmp |= B53SPI_MSPI_SPCR2_CONT_AFTER_CMD;
 208         bcm53xxspi_write(b53spi, B53SPI_MSPI_SPCR2, tmp);
 209
 210         /* Wait for SPI to finish */
 211         bcm53xxspi_wait(b53spi, bcm53xxspi_calc_timeout(len));
 212
 213         if (!cont)
 214                 bcm53xxspi_write(b53spi, B53SPI_MSPI_WRITE_LOCK, 0);
 215
 216         for (i = 0; i < len; ++i) {
 217                 int offset = b53spi->read_offset + i;
 218
 219                 /* Data stored in the transmit register file LSB */
 220                 r_buf[i] = (u8)bcm53xxspi_read(b53spi, B53SPI_MSPI_RXRAM + 4 * (1 + offset * 2));
 221         }
 222
 223         b53spi->read_offset = 0;
 224 }
 225
 226 static int bcm53xxspi_transfer_one(struct spi_master *master,
 227                                    struct spi_device *spi,
 228                                    struct spi_transfer *t)
 229 {
 230         struct bcm53xxspi *b53spi = spi_master_get_devdata(master);
 231         u8 *buf;
 232         size_t left;
 233
 234         bcm53xxspi_disable_bspi(b53spi);
 235
 236         if (t->tx_buf) {
 237                 buf = (u8 *)t->tx_buf;
 238                 left = t->len;
 239                 while (left) {
 240                         size_t to_write = min_t(size_t, 16, left);
 241                         bool cont = left - to_write > 0;
 242
 243                         bcm53xxspi_buf_write(b53spi, buf, to_write, cont);
 244                         left -= to_write;
 245                         buf += to_write;
 246                 }
 247         }
 248
 249         if (t->rx_buf) {
 250                 buf = (u8 *)t->rx_buf;
 251                 left = t->len;
 252                 while (left) {
 253                         size_t to_read = min_t(size_t, 16 - b53spi->read_offset,
 254                                                left);
 255                         bool cont = left - to_read > 0;
 256
 257                         bcm53xxspi_buf_read(b53spi, buf, to_read, cont);
 258                         left -= to_read;
 259                         buf += to_read;
 260                 }
 261         }
 262
 263         return 0;
 264 }
 265
 266 static int bcm53xxspi_flash_read(struct spi_device *spi,
 267                                  struct spi_flash_read_message *msg)
 268 {
 269         struct bcm53xxspi *b53spi = spi_master_get_devdata(spi->master);
 270         int ret = 0;
 271
 272         if (msg->from + msg->len > BCM53XXSPI_FLASH_WINDOW)
 273                 return -EINVAL;
 274
 275         bcm53xxspi_enable_bspi(b53spi);
 276         memcpy_fromio(msg->buf, b53spi->mmio_base + msg->from, msg->len);
 277         msg->retlen = msg->len;
 278
 279         return ret;
 280 }
 281
 282 /**************************************************
 283  * BCMA
 284  **************************************************/
 285
 286 static const struct bcma_device_id bcm53xxspi_bcma_tbl[] = {
 287         BCMA_CORE(BCMA_MANUF_BCM, BCMA_CORE_NS_QSPI, BCMA_ANY_REV, BCMA_ANY_CLASS),
 288         {},
 289 };
 290 MODULE_DEVICE_TABLE(bcma, bcm53xxspi_bcma_tbl);
 291
 292 static int bcm53xxspi_bcma_probe(struct bcma_device *core)
 293 {
 294         struct device *dev = &core->dev;
 295         struct bcm53xxspi *b53spi;
 296         struct spi_master *master;
 297         int err;
 298
 299         if (core->bus->drv_cc.core->id.rev != 42) {
 300                 pr_err("SPI on SoC with unsupported ChipCommon rev\n");
 301                 return -ENOTSUPP;
 302         }
 303
 304         master = spi_alloc_master(dev, sizeof(*b53spi));
 305         if (!master)
 306                 return -ENOMEM;
 307
 308         b53spi = spi_master_get_devdata(master);
 309         b53spi->master = master;
 310         b53spi->core = core;
 311
 312         if (core->addr_s[0])
 313                 b53spi->mmio_base = devm_ioremap(dev, core->addr_s[0],
 314                                                  BCM53XXSPI_FLASH_WINDOW);
 315         b53spi->bspi = true;
 316         bcm53xxspi_disable_bspi(b53spi);
 317
 318         master->dev.of_node = dev->of_node;
 319         master->transfer_one = bcm53xxspi_transfer_one;
 320         if (b53spi->mmio_base)
 321                 master->spi_flash_read = bcm53xxspi_flash_read;
 322
 323         bcma_set_drvdata(core, b53spi);
 324
 325         err = devm_spi_register_master(dev, master);
 326         if (err) {
 327                 spi_master_put(master);
 328                 bcma_set_drvdata(core, NULL);
 329                 return err;
 330         }
 331
 332         return 0;
 333 }
 334
 335 static struct bcma_driver bcm53xxspi_bcma_driver = {
 336         .name           = KBUILD_MODNAME,
 337         .id_table       = bcm53xxspi_bcma_tbl,
 338         .probe          = bcm53xxspi_bcma_probe,
 339 };
 340
 341 /**************************************************
 342  * Init & exit
 343  **************************************************/
 344
 345 static int __init bcm53xxspi_module_init(void)
 346 {
 347         int err = 0;
 348
 349         err = bcma_driver_register(&bcm53xxspi_bcma_driver);
 350         if (err)
 351                 pr_err("Failed to register bcma driver: %d\n", err);
 352
 353         return err;
 354 }
 355
 356 static void __exit bcm53xxspi_module_exit(void)
 357 {
 358         bcma_driver_unregister(&bcm53xxspi_bcma_driver);
 359 }
 360
 361 module_init(bcm53xxspi_module_init);
 362 module_exit(bcm53xxspi_module_exit);
 363
 364 MODULE_DESCRIPTION("Broadcom BCM53xx SPI Controller driver");
 365 MODULE_AUTHOR("Rafał Miłecki <zajec5@gmail.com>");
 366 MODULE_LICENSE("GPL v2");