drivers/spi/spi-oc-tiny.c

   1 /*
   2  * OpenCores tiny SPI master driver
   3  *
   4  * http://opencores.org/project,tiny_spi
   5  *
   6  * Copyright (C) 2011 Thomas Chou <thomas@wytron.com.tw>
   7  *
   8  * Based on spi_s3c24xx.c, which is:
   9  * Copyright (c) 2006 Ben Dooks
  10  * Copyright (c) 2006 Simtec Electronics
  11  *      Ben Dooks <ben@simtec.co.uk>
  12  *
  13  * This program is free software; you can redistribute it and/or modify
  14  * it under the terms of the GNU General Public License version 2 as
  15  * published by the Free Software Foundation.
  16  */
  17
  18 #include <linux/init.h>
  19 #include <linux/interrupt.h>
  20 #include <linux/errno.h>
  21 #include <linux/platform_device.h>
  22 #include <linux/spi/spi.h>
  23 #include <linux/spi/spi_bitbang.h>
  24 #include <linux/spi/spi_oc_tiny.h>
  25 #include <linux/io.h>
  26 #include <linux/gpio.h>
  27 #include <linux/of.h>
  28
  29 #define DRV_NAME "spi_oc_tiny"
  30
  31 #define TINY_SPI_RXDATA 0
  32 #define TINY_SPI_TXDATA 4
  33 #define TINY_SPI_STATUS 8
  34 #define TINY_SPI_CONTROL 12
  35 #define TINY_SPI_BAUD 16
  36
  37 #define TINY_SPI_STATUS_TXE 0x1
  38 #define TINY_SPI_STATUS_TXR 0x2
  39
  40 struct tiny_spi {
  41         /* bitbang has to be first */
  42         struct spi_bitbang bitbang;
  43         struct completion done;
  44
  45         void __iomem *base;
  46         int irq;
  47         unsigned int freq;
  48         unsigned int baudwidth;
  49         unsigned int baud;
  50         unsigned int speed_hz;
  51         unsigned int mode;
  52         unsigned int len;
  53         unsigned int txc, rxc;
  54         const u8 *txp;
  55         u8 *rxp;
  56         unsigned int gpio_cs_count;
  57         int *gpio_cs;
  58 };
  59
  60 static inline struct tiny_spi *tiny_spi_to_hw(struct spi_device *sdev)
  61 {
  62         return spi_master_get_devdata(sdev->master);
  63 }
  64
  65 static unsigned int tiny_spi_baud(struct spi_device *spi, unsigned int hz)
  66 {
  67         struct tiny_spi *hw = tiny_spi_to_hw(spi);
  68
  69         return min(DIV_ROUND_UP(hw->freq, hz * 2), (1U << hw->baudwidth)) - 1;
  70 }
  71
  72 static void tiny_spi_chipselect(struct spi_device *spi, int is_active)
  73 {
  74         struct tiny_spi *hw = tiny_spi_to_hw(spi);
  75
  76         if (hw->gpio_cs_count) {
  77                 gpio_set_value(hw->gpio_cs[spi->chip_select],
  78                         (spi->mode & SPI_CS_HIGH) ? is_active : !is_active);
  79         }
  80 }
  81
  82 static int tiny_spi_setup_transfer(struct spi_device *spi,
  83                                    struct spi_transfer *t)
  84 {
  85         struct tiny_spi *hw = tiny_spi_to_hw(spi);
  86         unsigned int baud = hw->baud;
  87
  88         if (t) {
  89                 if (t->speed_hz && t->speed_hz != hw->speed_hz)
  90                         baud = tiny_spi_baud(spi, t->speed_hz);
  91         }
  92         writel(baud, hw->base + TINY_SPI_BAUD);
  93         writel(hw->mode, hw->base + TINY_SPI_CONTROL);
  94         return 0;
  95 }
  96
  97 static int tiny_spi_setup(struct spi_device *spi)
  98 {
  99         struct tiny_spi *hw = tiny_spi_to_hw(spi);
 100
 101         if (spi->max_speed_hz != hw->speed_hz) {
 102                 hw->speed_hz = spi->max_speed_hz;
 103                 hw->baud = tiny_spi_baud(spi, hw->speed_hz);
 104         }
 105         hw->mode = spi->mode & (SPI_CPOL | SPI_CPHA);
 106         return 0;
 107 }
 108
 109 static inline void tiny_spi_wait_txr(struct tiny_spi *hw)
 110 {
 111         while (!(readb(hw->base + TINY_SPI_STATUS) &
 112                  TINY_SPI_STATUS_TXR))
 113                 cpu_relax();
 114 }
 115
 116 static inline void tiny_spi_wait_txe(struct tiny_spi *hw)
 117 {
 118         while (!(readb(hw->base + TINY_SPI_STATUS) &
 119                  TINY_SPI_STATUS_TXE))
 120                 cpu_relax();
 121 }
 122
 123 static int tiny_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t)
 124 {
 125         struct tiny_spi *hw = tiny_spi_to_hw(spi);
 126         const u8 *txp = t->tx_buf;
 127         u8 *rxp = t->rx_buf;
 128         unsigned int i;
 129
 130         if (hw->irq >= 0) {
 131                 /* use intrrupt driven data transfer */
 132                 hw->len = t->len;
 133                 hw->txp = t->tx_buf;
 134                 hw->rxp = t->rx_buf;
 135                 hw->txc = 0;
 136                 hw->rxc = 0;
 137
 138                 /* send the first byte */
 139                 if (t->len > 1) {
 140                         writeb(hw->txp ? *hw->txp++ : 0,
 141                                hw->base + TINY_SPI_TXDATA);
 142                         hw->txc++;
 143                         writeb(hw->txp ? *hw->txp++ : 0,
 144                                hw->base + TINY_SPI_TXDATA);
 145                         hw->txc++;
 146                         writeb(TINY_SPI_STATUS_TXR, hw->base + TINY_SPI_STATUS);
 147                 } else {
 148                         writeb(hw->txp ? *hw->txp++ : 0,
 149                                hw->base + TINY_SPI_TXDATA);
 150                         hw->txc++;
 151                         writeb(TINY_SPI_STATUS_TXE, hw->base + TINY_SPI_STATUS);
 152                 }
 153
 154                 wait_for_completion(&hw->done);
 155         } else if (txp && rxp) {
 156                 /* we need to tighten the transfer loop */
 157                 writeb(*txp++, hw->base + TINY_SPI_TXDATA);
 158                 if (t->len > 1) {
 159                         writeb(*txp++, hw->base + TINY_SPI_TXDATA);
 160                         for (i = 2; i < t->len; i++) {
 161                                 u8 rx, tx = *txp++;
 162                                 tiny_spi_wait_txr(hw);
 163                                 rx = readb(hw->base + TINY_SPI_TXDATA);
 164                                 writeb(tx, hw->base + TINY_SPI_TXDATA);
 165                                 *rxp++ = rx;
 166                         }
 167                         tiny_spi_wait_txr(hw);
 168                         *rxp++ = readb(hw->base + TINY_SPI_TXDATA);
 169                 }
 170                 tiny_spi_wait_txe(hw);
 171                 *rxp++ = readb(hw->base + TINY_SPI_RXDATA);
 172         } else if (rxp) {
 173                 writeb(0, hw->base + TINY_SPI_TXDATA);
 174                 if (t->len > 1) {
 175                         writeb(0,
 176                                hw->base + TINY_SPI_TXDATA);
 177                         for (i = 2; i < t->len; i++) {
 178                                 u8 rx;
 179                                 tiny_spi_wait_txr(hw);
 180                                 rx = readb(hw->base + TINY_SPI_TXDATA);
 181                                 writeb(0, hw->base + TINY_SPI_TXDATA);
 182                                 *rxp++ = rx;
 183                         }
 184                         tiny_spi_wait_txr(hw);
 185                         *rxp++ = readb(hw->base + TINY_SPI_TXDATA);
 186                 }
 187                 tiny_spi_wait_txe(hw);
 188                 *rxp++ = readb(hw->base + TINY_SPI_RXDATA);
 189         } else if (txp) {
 190                 writeb(*txp++, hw->base + TINY_SPI_TXDATA);
 191                 if (t->len > 1) {
 192                         writeb(*txp++, hw->base + TINY_SPI_TXDATA);
 193                         for (i = 2; i < t->len; i++) {
 194                                 u8 tx = *txp++;
 195                                 tiny_spi_wait_txr(hw);
 196                                 writeb(tx, hw->base + TINY_SPI_TXDATA);
 197                         }
 198                 }
 199                 tiny_spi_wait_txe(hw);
 200         } else {
 201                 writeb(0, hw->base + TINY_SPI_TXDATA);
 202                 if (t->len > 1) {
 203                         writeb(0, hw->base + TINY_SPI_TXDATA);
 204                         for (i = 2; i < t->len; i++) {
 205                                 tiny_spi_wait_txr(hw);
 206                                 writeb(0, hw->base + TINY_SPI_TXDATA);
 207                         }
 208                 }
 209                 tiny_spi_wait_txe(hw);
 210         }
 211         return t->len;
 212 }
 213
 214 static irqreturn_t tiny_spi_irq(int irq, void *dev)
 215 {
 216         struct tiny_spi *hw = dev;
 217
 218         writeb(0, hw->base + TINY_SPI_STATUS);
 219         if (hw->rxc + 1 == hw->len) {
 220                 if (hw->rxp)
 221                         *hw->rxp++ = readb(hw->base + TINY_SPI_RXDATA);
 222                 hw->rxc++;
 223                 complete(&hw->done);
 224         } else {
 225                 if (hw->rxp)
 226                         *hw->rxp++ = readb(hw->base + TINY_SPI_TXDATA);
 227                 hw->rxc++;
 228                 if (hw->txc < hw->len) {
 229                         writeb(hw->txp ? *hw->txp++ : 0,
 230                                hw->base + TINY_SPI_TXDATA);
 231                         hw->txc++;
 232                         writeb(TINY_SPI_STATUS_TXR,
 233                                hw->base + TINY_SPI_STATUS);
 234                 } else {
 235                         writeb(TINY_SPI_STATUS_TXE,
 236                                hw->base + TINY_SPI_STATUS);
 237                 }
 238         }
 239         return IRQ_HANDLED;
 240 }
 241
 242 #ifdef CONFIG_OF
 243 #include <linux/of_gpio.h>
 244
 245 static int __devinit tiny_spi_of_probe(struct platform_device *pdev)
 246 {
 247         struct tiny_spi *hw = platform_get_drvdata(pdev);
 248         struct device_node *np = pdev->dev.of_node;
 249         unsigned int i;
 250         const __be32 *val;
 251         int len;
 252
 253         if (!np)
 254                 return 0;
 255         hw->gpio_cs_count = of_gpio_count(np);
 256         if (hw->gpio_cs_count) {
 257                 hw->gpio_cs = devm_kzalloc(&pdev->dev,
 258                                 hw->gpio_cs_count * sizeof(unsigned int),
 259                                 GFP_KERNEL);
 260                 if (!hw->gpio_cs)
 261                         return -ENOMEM;
 262         }
 263         for (i = 0; i < hw->gpio_cs_count; i++) {
 264                 hw->gpio_cs[i] = of_get_gpio_flags(np, i, NULL);
 265                 if (hw->gpio_cs[i] < 0)
 266                         return -ENODEV;
 267         }
 268         hw->bitbang.master->dev.of_node = pdev->dev.of_node;
 269         val = of_get_property(pdev->dev.of_node,
 270                               "clock-frequency", &len);
 271         if (val && len >= sizeof(__be32))
 272                 hw->freq = be32_to_cpup(val);
 273         val = of_get_property(pdev->dev.of_node, "baud-width", &len);
 274         if (val && len >= sizeof(__be32))
 275                 hw->baudwidth = be32_to_cpup(val);
 276         return 0;
 277 }
 278 #else /* !CONFIG_OF */
 279 static int __devinit tiny_spi_of_probe(struct platform_device *pdev)
 280 {
 281         return 0;
 282 }
 283 #endif /* CONFIG_OF */
 284
 285 static int __devinit tiny_spi_probe(struct platform_device *pdev)
 286 {
 287         struct tiny_spi_platform_data *platp = pdev->dev.platform_data;
 288         struct tiny_spi *hw;
 289         struct spi_master *master;
 290         struct resource *res;
 291         unsigned int i;
 292         int err = -ENODEV;
 293
 294         master = spi_alloc_master(&pdev->dev, sizeof(struct tiny_spi));
 295         if (!master)
 296                 return err;
 297
 298         /* setup the master state. */
 299         master->bus_num = pdev->id;
 300         master->num_chipselect = 255;
 301         master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
 302         master->setup = tiny_spi_setup;
 303
 304         hw = spi_master_get_devdata(master);
 305         platform_set_drvdata(pdev, hw);
 306
 307         /* setup the state for the bitbang driver */
 308         hw->bitbang.master = spi_master_get(master);
 309         if (!hw->bitbang.master)
 310                 return err;
 311         hw->bitbang.setup_transfer = tiny_spi_setup_transfer;
 312         hw->bitbang.chipselect = tiny_spi_chipselect;
 313         hw->bitbang.txrx_bufs = tiny_spi_txrx_bufs;
 314
 315         /* find and map our resources */
 316         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 317         if (!res)
 318                 goto exit_busy;
 319         if (!devm_request_mem_region(&pdev->dev, res->start, resource_size(res),
 320                                      pdev->name))
 321                 goto exit_busy;
 322         hw->base = devm_ioremap_nocache(&pdev->dev, res->start,
 323                                         resource_size(res));
 324         if (!hw->base)
 325                 goto exit_busy;
 326         /* irq is optional */
 327         hw->irq = platform_get_irq(pdev, 0);
 328         if (hw->irq >= 0) {
 329                 init_completion(&hw->done);
 330                 err = devm_request_irq(&pdev->dev, hw->irq, tiny_spi_irq, 0,
 331                                        pdev->name, hw);
 332                 if (err)
 333                         goto exit;
 334         }
 335         /* find platform data */
 336         if (platp) {
 337                 hw->gpio_cs_count = platp->gpio_cs_count;
 338                 hw->gpio_cs = platp->gpio_cs;
 339                 if (platp->gpio_cs_count && !platp->gpio_cs)
 340                         goto exit_busy;
 341                 hw->freq = platp->freq;
 342                 hw->baudwidth = platp->baudwidth;
 343         } else {
 344                 err = tiny_spi_of_probe(pdev);
 345                 if (err)
 346                         goto exit;
 347         }
 348         for (i = 0; i < hw->gpio_cs_count; i++) {
 349                 err = gpio_request(hw->gpio_cs[i], dev_name(&pdev->dev));
 350                 if (err)
 351                         goto exit_gpio;
 352                 gpio_direction_output(hw->gpio_cs[i], 1);
 353         }
 354         hw->bitbang.master->num_chipselect = max(1U, hw->gpio_cs_count);
 355
 356         /* register our spi controller */
 357         err = spi_bitbang_start(&hw->bitbang);
 358         if (err)
 359                 goto exit;
 360         dev_info(&pdev->dev, "base %p, irq %d\n", hw->base, hw->irq);
 361
 362         return 0;
 363
 364 exit_gpio:
 365         while (i-- > 0)
 366                 gpio_free(hw->gpio_cs[i]);
 367 exit_busy:
 368         err = -EBUSY;
 369 exit:
 370         platform_set_drvdata(pdev, NULL);
 371         spi_master_put(master);
 372         return err;
 373 }
 374
 375 static int __devexit tiny_spi_remove(struct platform_device *pdev)
 376 {
 377         struct tiny_spi *hw = platform_get_drvdata(pdev);
 378         struct spi_master *master = hw->bitbang.master;
 379         unsigned int i;
 380
 381         spi_bitbang_stop(&hw->bitbang);
 382         for (i = 0; i < hw->gpio_cs_count; i++)
 383                 gpio_free(hw->gpio_cs[i]);
 384         platform_set_drvdata(pdev, NULL);
 385         spi_master_put(master);
 386         return 0;
 387 }
 388
 389 #ifdef CONFIG_OF
 390 static const struct of_device_id tiny_spi_match[] = {
 391         { .compatible = "opencores,tiny-spi-rtlsvn2", },
 392         {},
 393 };
 394 MODULE_DEVICE_TABLE(of, tiny_spi_match);
 395 #else /* CONFIG_OF */
 396 #define tiny_spi_match NULL
 397 #endif /* CONFIG_OF */
 398
 399 static struct platform_driver tiny_spi_driver = {
 400         .probe = tiny_spi_probe,
 401         .remove = __devexit_p(tiny_spi_remove),
 402         .driver = {
 403                 .name = DRV_NAME,
 404                 .owner = THIS_MODULE,
 405                 .pm = NULL,
 406                 .of_match_table = tiny_spi_match,
 407         },
 408 };
 409
 410 static int __init tiny_spi_init(void)
 411 {
 412         return platform_driver_register(&tiny_spi_driver);
 413 }
 414 module_init(tiny_spi_init);
 415
 416 static void __exit tiny_spi_exit(void)
 417 {
 418         platform_driver_unregister(&tiny_spi_driver);
 419 }
 420 module_exit(tiny_spi_exit);
 421
 422 MODULE_DESCRIPTION("OpenCores tiny SPI driver");
 423 MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
 424 MODULE_LICENSE("GPL");
 425 MODULE_ALIAS("platform:" DRV_NAME);