drivers/spi/spi_altera.c

   1 /*
   2  * Altera SPI driver
   3  *
   4  * Copyright (C) 2008 Thomas Chou <thomas@wytron.com.tw>
   5  *
   6  * Based on spi_s3c24xx.c, which is:
   7  * Copyright (c) 2006 Ben Dooks
   8  * Copyright (c) 2006 Simtec Electronics
   9  *      Ben Dooks <ben@simtec.co.uk>
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License version 2 as
  13  * published by the Free Software Foundation.
  14  */
  15
  16 #include <linux/init.h>
  17 #include <linux/interrupt.h>
  18 #include <linux/errno.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/spi/spi.h>
  21 #include <linux/spi/spi_bitbang.h>
  22 #include <linux/io.h>
  23 #include <linux/of.h>
  24
  25 #define DRV_NAME "spi_altera"
  26
  27 #define ALTERA_SPI_RXDATA       0
  28 #define ALTERA_SPI_TXDATA       4
  29 #define ALTERA_SPI_STATUS       8
  30 #define ALTERA_SPI_CONTROL      12
  31 #define ALTERA_SPI_SLAVE_SEL    20
  32
  33 #define ALTERA_SPI_STATUS_ROE_MSK       0x8
  34 #define ALTERA_SPI_STATUS_TOE_MSK       0x10
  35 #define ALTERA_SPI_STATUS_TMT_MSK       0x20
  36 #define ALTERA_SPI_STATUS_TRDY_MSK      0x40
  37 #define ALTERA_SPI_STATUS_RRDY_MSK      0x80
  38 #define ALTERA_SPI_STATUS_E_MSK         0x100
  39
  40 #define ALTERA_SPI_CONTROL_IROE_MSK     0x8
  41 #define ALTERA_SPI_CONTROL_ITOE_MSK     0x10
  42 #define ALTERA_SPI_CONTROL_ITRDY_MSK    0x40
  43 #define ALTERA_SPI_CONTROL_IRRDY_MSK    0x80
  44 #define ALTERA_SPI_CONTROL_IE_MSK       0x100
  45 #define ALTERA_SPI_CONTROL_SSO_MSK      0x400
  46
  47 struct altera_spi {
  48         /* bitbang has to be first */
  49         struct spi_bitbang bitbang;
  50         struct completion done;
  51
  52         void __iomem *base;
  53         int irq;
  54         int len;
  55         int count;
  56         int bytes_per_word;
  57         unsigned long imr;
  58
  59         /* data buffers */
  60         const unsigned char *tx;
  61         unsigned char *rx;
  62 };
  63
  64 static inline struct altera_spi *altera_spi_to_hw(struct spi_device *sdev)
  65 {
  66         return spi_master_get_devdata(sdev->master);
  67 }
  68
  69 static void altera_spi_chipsel(struct spi_device *spi, int value)
  70 {
  71         struct altera_spi *hw = altera_spi_to_hw(spi);
  72
  73         if (spi->mode & SPI_CS_HIGH) {
  74                 switch (value) {
  75                 case BITBANG_CS_INACTIVE:
  76                         writel(1 << spi->chip_select,
  77                                hw->base + ALTERA_SPI_SLAVE_SEL);
  78                         hw->imr |= ALTERA_SPI_CONTROL_SSO_MSK;
  79                         writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
  80                         break;
  81
  82                 case BITBANG_CS_ACTIVE:
  83                         hw->imr &= ~ALTERA_SPI_CONTROL_SSO_MSK;
  84                         writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
  85                         writel(0, hw->base + ALTERA_SPI_SLAVE_SEL);
  86                         break;
  87                 }
  88         } else {
  89                 switch (value) {
  90                 case BITBANG_CS_INACTIVE:
  91                         hw->imr &= ~ALTERA_SPI_CONTROL_SSO_MSK;
  92                         writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
  93                         break;
  94
  95                 case BITBANG_CS_ACTIVE:
  96                         writel(1 << spi->chip_select,
  97                                hw->base + ALTERA_SPI_SLAVE_SEL);
  98                         hw->imr |= ALTERA_SPI_CONTROL_SSO_MSK;
  99                         writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
 100                         break;
 101                 }
 102         }
 103 }
 104
 105 static int altera_spi_setupxfer(struct spi_device *spi, struct spi_transfer *t)
 106 {
 107         return 0;
 108 }
 109
 110 static int altera_spi_setup(struct spi_device *spi)
 111 {
 112         return 0;
 113 }
 114
 115 static inline unsigned int hw_txbyte(struct altera_spi *hw, int count)
 116 {
 117         if (hw->tx) {
 118                 switch (hw->bytes_per_word) {
 119                 case 1:
 120                         return hw->tx[count];
 121                 case 2:
 122                         return (hw->tx[count * 2]
 123                                 | (hw->tx[count * 2 + 1] << 8));
 124                 }
 125         }
 126         return 0;
 127 }
 128
 129 static int altera_spi_txrx(struct spi_device *spi, struct spi_transfer *t)
 130 {
 131         struct altera_spi *hw = altera_spi_to_hw(spi);
 132
 133         hw->tx = t->tx_buf;
 134         hw->rx = t->rx_buf;
 135         hw->count = 0;
 136         hw->bytes_per_word = (t->bits_per_word ? : spi->bits_per_word) / 8;
 137         hw->len = t->len / hw->bytes_per_word;
 138
 139         if (hw->irq >= 0) {
 140                 /* enable receive interrupt */
 141                 hw->imr |= ALTERA_SPI_CONTROL_IRRDY_MSK;
 142                 writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
 143
 144                 /* send the first byte */
 145                 writel(hw_txbyte(hw, 0), hw->base + ALTERA_SPI_TXDATA);
 146
 147                 wait_for_completion(&hw->done);
 148                 /* disable receive interrupt */
 149                 hw->imr &= ~ALTERA_SPI_CONTROL_IRRDY_MSK;
 150                 writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
 151         } else {
 152                 /* send the first byte */
 153                 writel(hw_txbyte(hw, 0), hw->base + ALTERA_SPI_TXDATA);
 154
 155                 while (1) {
 156                         unsigned int rxd;
 157
 158                         while (!(readl(hw->base + ALTERA_SPI_STATUS) &
 159                                  ALTERA_SPI_STATUS_RRDY_MSK))
 160                                 cpu_relax();
 161
 162                         rxd = readl(hw->base + ALTERA_SPI_RXDATA);
 163                         if (hw->rx) {
 164                                 switch (hw->bytes_per_word) {
 165                                 case 1:
 166                                         hw->rx[hw->count] = rxd;
 167                                         break;
 168                                 case 2:
 169                                         hw->rx[hw->count * 2] = rxd;
 170                                         hw->rx[hw->count * 2 + 1] = rxd >> 8;
 171                                         break;
 172                                 }
 173                         }
 174
 175                         hw->count++;
 176
 177                         if (hw->count < hw->len)
 178                                 writel(hw_txbyte(hw, hw->count),
 179                                        hw->base + ALTERA_SPI_TXDATA);
 180                         else
 181                                 break;
 182                 }
 183
 184         }
 185
 186         return hw->count * hw->bytes_per_word;
 187 }
 188
 189 static irqreturn_t altera_spi_irq(int irq, void *dev)
 190 {
 191         struct altera_spi *hw = dev;
 192         unsigned int rxd;
 193
 194         rxd = readl(hw->base + ALTERA_SPI_RXDATA);
 195         if (hw->rx) {
 196                 switch (hw->bytes_per_word) {
 197                 case 1:
 198                         hw->rx[hw->count] = rxd;
 199                         break;
 200                 case 2:
 201                         hw->rx[hw->count * 2] = rxd;
 202                         hw->rx[hw->count * 2 + 1] = rxd >> 8;
 203                         break;
 204                 }
 205         }
 206
 207         hw->count++;
 208
 209         if (hw->count < hw->len)
 210                 writel(hw_txbyte(hw, hw->count), hw->base + ALTERA_SPI_TXDATA);
 211         else
 212                 complete(&hw->done);
 213
 214         return IRQ_HANDLED;
 215 }
 216
 217 static int __devinit altera_spi_probe(struct platform_device *pdev)
 218 {
 219         struct altera_spi_platform_data *platp = pdev->dev.platform_data;
 220         struct altera_spi *hw;
 221         struct spi_master *master;
 222         struct resource *res;
 223         int err = -ENODEV;
 224
 225         master = spi_alloc_master(&pdev->dev, sizeof(struct altera_spi));
 226         if (!master)
 227                 return err;
 228
 229         /* setup the master state. */
 230         master->bus_num = pdev->id;
 231         master->num_chipselect = 16;
 232         master->mode_bits = SPI_CS_HIGH;
 233         master->setup = altera_spi_setup;
 234
 235         hw = spi_master_get_devdata(master);
 236         platform_set_drvdata(pdev, hw);
 237
 238         /* setup the state for the bitbang driver */
 239         hw->bitbang.master = spi_master_get(master);
 240         if (!hw->bitbang.master)
 241                 return err;
 242         hw->bitbang.setup_transfer = altera_spi_setupxfer;
 243         hw->bitbang.chipselect = altera_spi_chipsel;
 244         hw->bitbang.txrx_bufs = altera_spi_txrx;
 245
 246         /* find and map our resources */
 247         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 248         if (!res)
 249                 goto exit_busy;
 250         if (!devm_request_mem_region(&pdev->dev, res->start, resource_size(res),
 251                                      pdev->name))
 252                 goto exit_busy;
 253         hw->base = devm_ioremap_nocache(&pdev->dev, res->start,
 254                                         resource_size(res));
 255         if (!hw->base)
 256                 goto exit_busy;
 257         /* program defaults into the registers */
 258         hw->imr = 0;            /* disable spi interrupts */
 259         writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
 260         writel(0, hw->base + ALTERA_SPI_STATUS);        /* clear status reg */
 261         if (readl(hw->base + ALTERA_SPI_STATUS) & ALTERA_SPI_STATUS_RRDY_MSK)
 262                 readl(hw->base + ALTERA_SPI_RXDATA);    /* flush rxdata */
 263         /* irq is optional */
 264         hw->irq = platform_get_irq(pdev, 0);
 265         if (hw->irq >= 0) {
 266                 init_completion(&hw->done);
 267                 err = devm_request_irq(&pdev->dev, hw->irq, altera_spi_irq, 0,
 268                                        pdev->name, hw);
 269                 if (err)
 270                         goto exit;
 271         }
 272         /* find platform data */
 273         if (!platp)
 274                 hw->bitbang.master->dev.of_node = pdev->dev.of_node;
 275
 276         /* register our spi controller */
 277         err = spi_bitbang_start(&hw->bitbang);
 278         if (err)
 279                 goto exit;
 280         dev_info(&pdev->dev, "base %p, irq %d\n", hw->base, hw->irq);
 281
 282         return 0;
 283
 284 exit_busy:
 285         err = -EBUSY;
 286 exit:
 287         platform_set_drvdata(pdev, NULL);
 288         spi_master_put(master);
 289         return err;
 290 }
 291
 292 static int __devexit altera_spi_remove(struct platform_device *dev)
 293 {
 294         struct altera_spi *hw = platform_get_drvdata(dev);
 295         struct spi_master *master = hw->bitbang.master;
 296
 297         spi_bitbang_stop(&hw->bitbang);
 298         platform_set_drvdata(dev, NULL);
 299         spi_master_put(master);
 300         return 0;
 301 }
 302
 303 #ifdef CONFIG_OF
 304 static const struct of_device_id altera_spi_match[] = {
 305         { .compatible = "ALTR,spi-1.0", },
 306         {},
 307 };
 308 MODULE_DEVICE_TABLE(of, altera_spi_match);
 309 #else /* CONFIG_OF */
 310 #define altera_spi_match NULL
 311 #endif /* CONFIG_OF */
 312
 313 static struct platform_driver altera_spi_driver = {
 314         .probe = altera_spi_probe,
 315         .remove = __devexit_p(altera_spi_remove),
 316         .driver = {
 317                 .name = DRV_NAME,
 318                 .owner = THIS_MODULE,
 319                 .pm = NULL,
 320                 .of_match_table = altera_spi_match,
 321         },
 322 };
 323
 324 static int __init altera_spi_init(void)
 325 {
 326         return platform_driver_register(&altera_spi_driver);
 327 }
 328 module_init(altera_spi_init);
 329
 330 static void __exit altera_spi_exit(void)
 331 {
 332         platform_driver_unregister(&altera_spi_driver);
 333 }
 334 module_exit(altera_spi_exit);
 335
 336 MODULE_DESCRIPTION("Altera SPI driver");
 337 MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
 338 MODULE_LICENSE("GPL");
 339 MODULE_ALIAS("platform:" DRV_NAME);