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 {
 157                 /* we need to tighten the transfer loop */
 158                 writeb(txp ? *txp++ : 0, hw->base + TINY_SPI_TXDATA);
 159                 for (i = 1; i < t->len; i++) {
 160                         writeb(txp ? *txp++ : 0, hw->base + TINY_SPI_TXDATA);
 161
 162                         if (rxp || (i != t->len - 1))
 163                                 tiny_spi_wait_txr(hw);
 164                         if (rxp)
 165                                 *rxp++ = readb(hw->base + TINY_SPI_TXDATA);
 166                 }
 167                 tiny_spi_wait_txe(hw);
 168                 if (rxp)
 169                         *rxp++ = readb(hw->base + TINY_SPI_RXDATA);
 170         }
 171
 172         return t->len;
 173 }
 174
 175 static irqreturn_t tiny_spi_irq(int irq, void *dev)
 176 {
 177         struct tiny_spi *hw = dev;
 178
 179         writeb(0, hw->base + TINY_SPI_STATUS);
 180         if (hw->rxc + 1 == hw->len) {
 181                 if (hw->rxp)
 182                         *hw->rxp++ = readb(hw->base + TINY_SPI_RXDATA);
 183                 hw->rxc++;
 184                 complete(&hw->done);
 185         } else {
 186                 if (hw->rxp)
 187                         *hw->rxp++ = readb(hw->base + TINY_SPI_TXDATA);
 188                 hw->rxc++;
 189                 if (hw->txc < hw->len) {
 190                         writeb(hw->txp ? *hw->txp++ : 0,
 191                                hw->base + TINY_SPI_TXDATA);
 192                         hw->txc++;
 193                         writeb(TINY_SPI_STATUS_TXR,
 194                                hw->base + TINY_SPI_STATUS);
 195                 } else {
 196                         writeb(TINY_SPI_STATUS_TXE,
 197                                hw->base + TINY_SPI_STATUS);
 198                 }
 199         }
 200         return IRQ_HANDLED;
 201 }
 202
 203 #ifdef CONFIG_OF
 204 #include <linux/of_gpio.h>
 205
 206 static int tiny_spi_of_probe(struct platform_device *pdev)
 207 {
 208         struct tiny_spi *hw = platform_get_drvdata(pdev);
 209         struct device_node *np = pdev->dev.of_node;
 210         unsigned int i;
 211         const __be32 *val;
 212         int len;
 213
 214         if (!np)
 215                 return 0;
 216         hw->gpio_cs_count = of_gpio_count(np);
 217         if (hw->gpio_cs_count > 0) {
 218                 hw->gpio_cs = devm_kzalloc(&pdev->dev,
 219                                 hw->gpio_cs_count * sizeof(unsigned int),
 220                                 GFP_KERNEL);
 221                 if (!hw->gpio_cs)
 222                         return -ENOMEM;
 223         }
 224         for (i = 0; i < hw->gpio_cs_count; i++) {
 225                 hw->gpio_cs[i] = of_get_gpio_flags(np, i, NULL);
 226                 if (hw->gpio_cs[i] < 0)
 227                         return -ENODEV;
 228         }
 229         hw->bitbang.master->dev.of_node = pdev->dev.of_node;
 230         val = of_get_property(pdev->dev.of_node,
 231                               "clock-frequency", &len);
 232         if (val && len >= sizeof(__be32))
 233                 hw->freq = be32_to_cpup(val);
 234         val = of_get_property(pdev->dev.of_node, "baud-width", &len);
 235         if (val && len >= sizeof(__be32))
 236                 hw->baudwidth = be32_to_cpup(val);
 237         return 0;
 238 }
 239 #else /* !CONFIG_OF */
 240 static int tiny_spi_of_probe(struct platform_device *pdev)
 241 {
 242         return 0;
 243 }
 244 #endif /* CONFIG_OF */
 245
 246 static int tiny_spi_probe(struct platform_device *pdev)
 247 {
 248         struct tiny_spi_platform_data *platp = dev_get_platdata(&pdev->dev);
 249         struct tiny_spi *hw;
 250         struct spi_master *master;
 251         struct resource *res;
 252         unsigned int i;
 253         int err = -ENODEV;
 254
 255         master = spi_alloc_master(&pdev->dev, sizeof(struct tiny_spi));
 256         if (!master)
 257                 return err;
 258
 259         /* setup the master state. */
 260         master->bus_num = pdev->id;
 261         master->num_chipselect = 255;
 262         master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
 263         master->setup = tiny_spi_setup;
 264
 265         hw = spi_master_get_devdata(master);
 266         platform_set_drvdata(pdev, hw);
 267
 268         /* setup the state for the bitbang driver */
 269         hw->bitbang.master = master;
 270         if (!hw->bitbang.master)
 271                 return err;
 272         hw->bitbang.setup_transfer = tiny_spi_setup_transfer;
 273         hw->bitbang.chipselect = tiny_spi_chipselect;
 274         hw->bitbang.txrx_bufs = tiny_spi_txrx_bufs;
 275
 276         /* find and map our resources */
 277         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 278         hw->base = devm_ioremap_resource(&pdev->dev, res);
 279         if (IS_ERR(hw->base)) {
 280                 err = PTR_ERR(hw->base);
 281                 goto exit;
 282         }
 283         /* irq is optional */
 284         hw->irq = platform_get_irq(pdev, 0);
 285         if (hw->irq >= 0) {
 286                 init_completion(&hw->done);
 287                 err = devm_request_irq(&pdev->dev, hw->irq, tiny_spi_irq, 0,
 288                                        pdev->name, hw);
 289                 if (err)
 290                         goto exit;
 291         }
 292         /* find platform data */
 293         if (platp) {
 294                 hw->gpio_cs_count = platp->gpio_cs_count;
 295                 hw->gpio_cs = platp->gpio_cs;
 296                 if (platp->gpio_cs_count && !platp->gpio_cs) {
 297                         err = -EBUSY;
 298                         goto exit;
 299                 }
 300                 hw->freq = platp->freq;
 301                 hw->baudwidth = platp->baudwidth;
 302         } else {
 303                 err = tiny_spi_of_probe(pdev);
 304                 if (err)
 305                         goto exit;
 306         }
 307         for (i = 0; i < hw->gpio_cs_count; i++) {
 308                 err = gpio_request(hw->gpio_cs[i], dev_name(&pdev->dev));
 309                 if (err)
 310                         goto exit_gpio;
 311                 gpio_direction_output(hw->gpio_cs[i], 1);
 312         }
 313         hw->bitbang.master->num_chipselect = max(1, hw->gpio_cs_count);
 314
 315         /* register our spi controller */
 316         err = spi_bitbang_start(&hw->bitbang);
 317         if (err)
 318                 goto exit;
 319         dev_info(&pdev->dev, "base %p, irq %d\n", hw->base, hw->irq);
 320
 321         return 0;
 322
 323 exit_gpio:
 324         while (i-- > 0)
 325                 gpio_free(hw->gpio_cs[i]);
 326 exit:
 327         spi_master_put(master);
 328         return err;
 329 }
 330
 331 static int tiny_spi_remove(struct platform_device *pdev)
 332 {
 333         struct tiny_spi *hw = platform_get_drvdata(pdev);
 334         struct spi_master *master = hw->bitbang.master;
 335         unsigned int i;
 336
 337         spi_bitbang_stop(&hw->bitbang);
 338         for (i = 0; i < hw->gpio_cs_count; i++)
 339                 gpio_free(hw->gpio_cs[i]);
 340         spi_master_put(master);
 341         return 0;
 342 }
 343
 344 #ifdef CONFIG_OF
 345 static const struct of_device_id tiny_spi_match[] = {
 346         { .compatible = "opencores,tiny-spi-rtlsvn2", },
 347         {},
 348 };
 349 MODULE_DEVICE_TABLE(of, tiny_spi_match);
 350 #endif /* CONFIG_OF */
 351
 352 static struct platform_driver tiny_spi_driver = {
 353         .probe = tiny_spi_probe,
 354         .remove = tiny_spi_remove,
 355         .driver = {
 356                 .name = DRV_NAME,
 357                 .owner = THIS_MODULE,
 358                 .pm = NULL,
 359                 .of_match_table = of_match_ptr(tiny_spi_match),
 360         },
 361 };
 362 module_platform_driver(tiny_spi_driver);
 363
 364 MODULE_DESCRIPTION("OpenCores tiny SPI driver");
 365 MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
 366 MODULE_LICENSE("GPL");
 367 MODULE_ALIAS("platform:" DRV_NAME);