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/interrupt.h>
  19 #include <linux/errno.h>
  20 #include <linux/module.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         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 > 0) {
  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 interrupt 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 {
 156                 /* we need to tighten the transfer loop */
 157                 writeb(txp ? *txp++ : 0, hw->base + TINY_SPI_TXDATA);
 158                 for (i = 1; i < t->len; i++) {
 159                         writeb(txp ? *txp++ : 0, hw->base + TINY_SPI_TXDATA);
 160
 161                         if (rxp || (i != t->len - 1))
 162                                 tiny_spi_wait_txr(hw);
 163                         if (rxp)
 164                                 *rxp++ = readb(hw->base + TINY_SPI_TXDATA);
 165                 }
 166                 tiny_spi_wait_txe(hw);
 167                 if (rxp)
 168                         *rxp++ = readb(hw->base + TINY_SPI_RXDATA);
 169         }
 170
 171         return t->len;
 172 }
 173
 174 static irqreturn_t tiny_spi_irq(int irq, void *dev)
 175 {
 176         struct tiny_spi *hw = dev;
 177
 178         writeb(0, hw->base + TINY_SPI_STATUS);
 179         if (hw->rxc + 1 == hw->len) {
 180                 if (hw->rxp)
 181                         *hw->rxp++ = readb(hw->base + TINY_SPI_RXDATA);
 182                 hw->rxc++;
 183                 complete(&hw->done);
 184         } else {
 185                 if (hw->rxp)
 186                         *hw->rxp++ = readb(hw->base + TINY_SPI_TXDATA);
 187                 hw->rxc++;
 188                 if (hw->txc < hw->len) {
 189                         writeb(hw->txp ? *hw->txp++ : 0,
 190                                hw->base + TINY_SPI_TXDATA);
 191                         hw->txc++;
 192                         writeb(TINY_SPI_STATUS_TXR,
 193                                hw->base + TINY_SPI_STATUS);
 194                 } else {
 195                         writeb(TINY_SPI_STATUS_TXE,
 196                                hw->base + TINY_SPI_STATUS);
 197                 }
 198         }
 199         return IRQ_HANDLED;
 200 }
 201
 202 #ifdef CONFIG_OF
 203 #include <linux/of_gpio.h>
 204
 205 static int tiny_spi_of_probe(struct platform_device *pdev)
 206 {
 207         struct tiny_spi *hw = platform_get_drvdata(pdev);
 208         struct device_node *np = pdev->dev.of_node;
 209         unsigned int i;
 210         u32 val;
 211
 212         if (!np)
 213                 return 0;
 214         hw->gpio_cs_count = of_gpio_count(np);
 215         if (hw->gpio_cs_count > 0) {
 216                 hw->gpio_cs = devm_kcalloc(&pdev->dev,
 217                                 hw->gpio_cs_count, sizeof(unsigned int),
 218                                 GFP_KERNEL);
 219                 if (!hw->gpio_cs)
 220                         return -ENOMEM;
 221         }
 222         for (i = 0; i < hw->gpio_cs_count; i++) {
 223                 hw->gpio_cs[i] = of_get_gpio_flags(np, i, NULL);
 224                 if (hw->gpio_cs[i] < 0)
 225                         return -ENODEV;
 226         }
 227         hw->bitbang.master->dev.of_node = pdev->dev.of_node;
 228         if (!of_property_read_u32(np, "clock-frequency", &val))
 229                 hw->freq = val;
 230         if (!of_property_read_u32(np, "baud-width", &val))
 231                 hw->baudwidth = val;
 232         return 0;
 233 }
 234 #else /* !CONFIG_OF */
 235 static int tiny_spi_of_probe(struct platform_device *pdev)
 236 {
 237         return 0;
 238 }
 239 #endif /* CONFIG_OF */
 240
 241 static int tiny_spi_probe(struct platform_device *pdev)
 242 {
 243         struct tiny_spi_platform_data *platp = dev_get_platdata(&pdev->dev);
 244         struct tiny_spi *hw;
 245         struct spi_master *master;
 246         struct resource *res;
 247         unsigned int i;
 248         int err = -ENODEV;
 249
 250         master = spi_alloc_master(&pdev->dev, sizeof(struct tiny_spi));
 251         if (!master)
 252                 return err;
 253
 254         /* setup the master state. */
 255         master->bus_num = pdev->id;
 256         master->num_chipselect = 255;
 257         master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
 258         master->setup = tiny_spi_setup;
 259
 260         hw = spi_master_get_devdata(master);
 261         platform_set_drvdata(pdev, hw);
 262
 263         /* setup the state for the bitbang driver */
 264         hw->bitbang.master = master;
 265         hw->bitbang.setup_transfer = tiny_spi_setup_transfer;
 266         hw->bitbang.chipselect = tiny_spi_chipselect;
 267         hw->bitbang.txrx_bufs = tiny_spi_txrx_bufs;
 268
 269         /* find and map our resources */
 270         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 271         hw->base = devm_ioremap_resource(&pdev->dev, res);
 272         if (IS_ERR(hw->base)) {
 273                 err = PTR_ERR(hw->base);
 274                 goto exit;
 275         }
 276         /* irq is optional */
 277         hw->irq = platform_get_irq(pdev, 0);
 278         if (hw->irq >= 0) {
 279                 init_completion(&hw->done);
 280                 err = devm_request_irq(&pdev->dev, hw->irq, tiny_spi_irq, 0,
 281                                        pdev->name, hw);
 282                 if (err)
 283                         goto exit;
 284         }
 285         /* find platform data */
 286         if (platp) {
 287                 hw->gpio_cs_count = platp->gpio_cs_count;
 288                 hw->gpio_cs = platp->gpio_cs;
 289                 if (platp->gpio_cs_count && !platp->gpio_cs) {
 290                         err = -EBUSY;
 291                         goto exit;
 292                 }
 293                 hw->freq = platp->freq;
 294                 hw->baudwidth = platp->baudwidth;
 295         } else {
 296                 err = tiny_spi_of_probe(pdev);
 297                 if (err)
 298                         goto exit;
 299         }
 300         for (i = 0; i < hw->gpio_cs_count; i++) {
 301                 err = gpio_request(hw->gpio_cs[i], dev_name(&pdev->dev));
 302                 if (err)
 303                         goto exit_gpio;
 304                 gpio_direction_output(hw->gpio_cs[i], 1);
 305         }
 306         hw->bitbang.master->num_chipselect = max(1, hw->gpio_cs_count);
 307
 308         /* register our spi controller */
 309         err = spi_bitbang_start(&hw->bitbang);
 310         if (err)
 311                 goto exit;
 312         dev_info(&pdev->dev, "base %p, irq %d\n", hw->base, hw->irq);
 313
 314         return 0;
 315
 316 exit_gpio:
 317         while (i-- > 0)
 318                 gpio_free(hw->gpio_cs[i]);
 319 exit:
 320         spi_master_put(master);
 321         return err;
 322 }
 323
 324 static int tiny_spi_remove(struct platform_device *pdev)
 325 {
 326         struct tiny_spi *hw = platform_get_drvdata(pdev);
 327         struct spi_master *master = hw->bitbang.master;
 328         unsigned int i;
 329
 330         spi_bitbang_stop(&hw->bitbang);
 331         for (i = 0; i < hw->gpio_cs_count; i++)
 332                 gpio_free(hw->gpio_cs[i]);
 333         spi_master_put(master);
 334         return 0;
 335 }
 336
 337 #ifdef CONFIG_OF
 338 static const struct of_device_id tiny_spi_match[] = {
 339         { .compatible = "opencores,tiny-spi-rtlsvn2", },
 340         {},
 341 };
 342 MODULE_DEVICE_TABLE(of, tiny_spi_match);
 343 #endif /* CONFIG_OF */
 344
 345 static struct platform_driver tiny_spi_driver = {
 346         .probe = tiny_spi_probe,
 347         .remove = tiny_spi_remove,
 348         .driver = {
 349                 .name = DRV_NAME,
 350                 .pm = NULL,
 351                 .of_match_table = of_match_ptr(tiny_spi_match),
 352         },
 353 };
 354 module_platform_driver(tiny_spi_driver);
 355
 356 MODULE_DESCRIPTION("OpenCores tiny SPI driver");
 357 MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
 358 MODULE_LICENSE("GPL");
 359 MODULE_ALIAS("platform:" DRV_NAME);