linux/drivers/spi/spi-oc-tiny.c
<<
>>
Prefs
   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
  41struct 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        unsigned int gpio_cs_count;
  58        int *gpio_cs;
  59};
  60
  61static inline struct tiny_spi *tiny_spi_to_hw(struct spi_device *sdev)
  62{
  63        return spi_master_get_devdata(sdev->master);
  64}
  65
  66static 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
  73static 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) {
  78                gpio_set_value(hw->gpio_cs[spi->chip_select],
  79                        (spi->mode & SPI_CS_HIGH) ? is_active : !is_active);
  80        }
  81}
  82
  83static 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
  98static 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
 110static 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
 117static 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
 124static 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
 215static 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
 246static 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) {
 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 */
 280static int tiny_spi_of_probe(struct platform_device *pdev)
 281{
 282        return 0;
 283}
 284#endif /* CONFIG_OF */
 285
 286static int tiny_spi_probe(struct platform_device *pdev)
 287{
 288        struct tiny_spi_platform_data *platp = pdev->dev.platform_data;
 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        if (!res)
 319                goto exit_busy;
 320        if (!devm_request_mem_region(&pdev->dev, res->start, resource_size(res),
 321                                     pdev->name))
 322                goto exit_busy;
 323        hw->base = devm_ioremap_nocache(&pdev->dev, res->start,
 324                                        resource_size(res));
 325        if (!hw->base)
 326                goto exit_busy;
 327        /* irq is optional */
 328        hw->irq = platform_get_irq(pdev, 0);
 329        if (hw->irq >= 0) {
 330                init_completion(&hw->done);
 331                err = devm_request_irq(&pdev->dev, hw->irq, tiny_spi_irq, 0,
 332                                       pdev->name, hw);
 333                if (err)
 334                        goto exit;
 335        }
 336        /* find platform data */
 337        if (platp) {
 338                hw->gpio_cs_count = platp->gpio_cs_count;
 339                hw->gpio_cs = platp->gpio_cs;
 340                if (platp->gpio_cs_count && !platp->gpio_cs)
 341                        goto exit_busy;
 342                hw->freq = platp->freq;
 343                hw->baudwidth = platp->baudwidth;
 344        } else {
 345                err = tiny_spi_of_probe(pdev);
 346                if (err)
 347                        goto exit;
 348        }
 349        for (i = 0; i < hw->gpio_cs_count; i++) {
 350                err = gpio_request(hw->gpio_cs[i], dev_name(&pdev->dev));
 351                if (err)
 352                        goto exit_gpio;
 353                gpio_direction_output(hw->gpio_cs[i], 1);
 354        }
 355        hw->bitbang.master->num_chipselect = max(1U, hw->gpio_cs_count);
 356
 357        /* register our spi controller */
 358        err = spi_bitbang_start(&hw->bitbang);
 359        if (err)
 360                goto exit;
 361        dev_info(&pdev->dev, "base %p, irq %d\n", hw->base, hw->irq);
 362
 363        return 0;
 364
 365exit_gpio:
 366        while (i-- > 0)
 367                gpio_free(hw->gpio_cs[i]);
 368exit_busy:
 369        err = -EBUSY;
 370exit:
 371        platform_set_drvdata(pdev, NULL);
 372        spi_master_put(master);
 373        return err;
 374}
 375
 376static int tiny_spi_remove(struct platform_device *pdev)
 377{
 378        struct tiny_spi *hw = platform_get_drvdata(pdev);
 379        struct spi_master *master = hw->bitbang.master;
 380        unsigned int i;
 381
 382        spi_bitbang_stop(&hw->bitbang);
 383        for (i = 0; i < hw->gpio_cs_count; i++)
 384                gpio_free(hw->gpio_cs[i]);
 385        platform_set_drvdata(pdev, NULL);
 386        spi_master_put(master);
 387        return 0;
 388}
 389
 390#ifdef CONFIG_OF
 391static const struct of_device_id tiny_spi_match[] = {
 392        { .compatible = "opencores,tiny-spi-rtlsvn2", },
 393        {},
 394};
 395MODULE_DEVICE_TABLE(of, tiny_spi_match);
 396#else /* CONFIG_OF */
 397#define tiny_spi_match NULL
 398#endif /* CONFIG_OF */
 399
 400static struct platform_driver tiny_spi_driver = {
 401        .probe = tiny_spi_probe,
 402        .remove = tiny_spi_remove,
 403        .driver = {
 404                .name = DRV_NAME,
 405                .owner = THIS_MODULE,
 406                .pm = NULL,
 407                .of_match_table = tiny_spi_match,
 408        },
 409};
 410module_platform_driver(tiny_spi_driver);
 411
 412MODULE_DESCRIPTION("OpenCores tiny SPI driver");
 413MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
 414MODULE_LICENSE("GPL");
 415MODULE_ALIAS("platform:" DRV_NAME);
 416
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.