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