linux/drivers/spi/spi-altera.c
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   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/interrupt.h>
  17#include <linux/errno.h>
  18#include <linux/module.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
  47struct 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
  64static inline struct altera_spi *altera_spi_to_hw(struct spi_device *sdev)
  65{
  66        return spi_master_get_devdata(sdev->master);
  67}
  68
  69static 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
 105static inline unsigned int hw_txbyte(struct altera_spi *hw, int count)
 106{
 107        if (hw->tx) {
 108                switch (hw->bytes_per_word) {
 109                case 1:
 110                        return hw->tx[count];
 111                case 2:
 112                        return (hw->tx[count * 2]
 113                                | (hw->tx[count * 2 + 1] << 8));
 114                }
 115        }
 116        return 0;
 117}
 118
 119static int altera_spi_txrx(struct spi_device *spi, struct spi_transfer *t)
 120{
 121        struct altera_spi *hw = altera_spi_to_hw(spi);
 122
 123        hw->tx = t->tx_buf;
 124        hw->rx = t->rx_buf;
 125        hw->count = 0;
 126        hw->bytes_per_word = DIV_ROUND_UP(t->bits_per_word, 8);
 127        hw->len = t->len / hw->bytes_per_word;
 128
 129        if (hw->irq >= 0) {
 130                /* enable receive interrupt */
 131                hw->imr |= ALTERA_SPI_CONTROL_IRRDY_MSK;
 132                writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
 133
 134                /* send the first byte */
 135                writel(hw_txbyte(hw, 0), hw->base + ALTERA_SPI_TXDATA);
 136
 137                wait_for_completion(&hw->done);
 138                /* disable receive interrupt */
 139                hw->imr &= ~ALTERA_SPI_CONTROL_IRRDY_MSK;
 140                writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
 141        } else {
 142                while (hw->count < hw->len) {
 143                        unsigned int rxd;
 144
 145                        writel(hw_txbyte(hw, hw->count),
 146                               hw->base + ALTERA_SPI_TXDATA);
 147
 148                        while (!(readl(hw->base + ALTERA_SPI_STATUS) &
 149                                 ALTERA_SPI_STATUS_RRDY_MSK))
 150                                cpu_relax();
 151
 152                        rxd = readl(hw->base + ALTERA_SPI_RXDATA);
 153                        if (hw->rx) {
 154                                switch (hw->bytes_per_word) {
 155                                case 1:
 156                                        hw->rx[hw->count] = rxd;
 157                                        break;
 158                                case 2:
 159                                        hw->rx[hw->count * 2] = rxd;
 160                                        hw->rx[hw->count * 2 + 1] = rxd >> 8;
 161                                        break;
 162                                }
 163                        }
 164
 165                        hw->count++;
 166                }
 167        }
 168
 169        return hw->count * hw->bytes_per_word;
 170}
 171
 172static irqreturn_t altera_spi_irq(int irq, void *dev)
 173{
 174        struct altera_spi *hw = dev;
 175        unsigned int rxd;
 176
 177        rxd = readl(hw->base + ALTERA_SPI_RXDATA);
 178        if (hw->rx) {
 179                switch (hw->bytes_per_word) {
 180                case 1:
 181                        hw->rx[hw->count] = rxd;
 182                        break;
 183                case 2:
 184                        hw->rx[hw->count * 2] = rxd;
 185                        hw->rx[hw->count * 2 + 1] = rxd >> 8;
 186                        break;
 187                }
 188        }
 189
 190        hw->count++;
 191
 192        if (hw->count < hw->len)
 193                writel(hw_txbyte(hw, hw->count), hw->base + ALTERA_SPI_TXDATA);
 194        else
 195                complete(&hw->done);
 196
 197        return IRQ_HANDLED;
 198}
 199
 200static int altera_spi_probe(struct platform_device *pdev)
 201{
 202        struct altera_spi *hw;
 203        struct spi_master *master;
 204        struct resource *res;
 205        int err = -ENODEV;
 206
 207        master = spi_alloc_master(&pdev->dev, sizeof(struct altera_spi));
 208        if (!master)
 209                return err;
 210
 211        /* setup the master state. */
 212        master->bus_num = pdev->id;
 213        master->num_chipselect = 16;
 214        master->mode_bits = SPI_CS_HIGH;
 215        master->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 16);
 216        master->dev.of_node = pdev->dev.of_node;
 217
 218        hw = spi_master_get_devdata(master);
 219        platform_set_drvdata(pdev, hw);
 220
 221        /* setup the state for the bitbang driver */
 222        hw->bitbang.master = master;
 223        hw->bitbang.chipselect = altera_spi_chipsel;
 224        hw->bitbang.txrx_bufs = altera_spi_txrx;
 225
 226        /* find and map our resources */
 227        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 228        hw->base = devm_ioremap_resource(&pdev->dev, res);
 229        if (IS_ERR(hw->base)) {
 230                err = PTR_ERR(hw->base);
 231                goto exit;
 232        }
 233        /* program defaults into the registers */
 234        hw->imr = 0;            /* disable spi interrupts */
 235        writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
 236        writel(0, hw->base + ALTERA_SPI_STATUS);        /* clear status reg */
 237        if (readl(hw->base + ALTERA_SPI_STATUS) & ALTERA_SPI_STATUS_RRDY_MSK)
 238                readl(hw->base + ALTERA_SPI_RXDATA);    /* flush rxdata */
 239        /* irq is optional */
 240        hw->irq = platform_get_irq(pdev, 0);
 241        if (hw->irq >= 0) {
 242                init_completion(&hw->done);
 243                err = devm_request_irq(&pdev->dev, hw->irq, altera_spi_irq, 0,
 244                                       pdev->name, hw);
 245                if (err)
 246                        goto exit;
 247        }
 248
 249        /* register our spi controller */
 250        err = spi_bitbang_start(&hw->bitbang);
 251        if (err)
 252                goto exit;
 253        dev_info(&pdev->dev, "base %p, irq %d\n", hw->base, hw->irq);
 254
 255        return 0;
 256exit:
 257        spi_master_put(master);
 258        return err;
 259}
 260
 261static int altera_spi_remove(struct platform_device *dev)
 262{
 263        struct altera_spi *hw = platform_get_drvdata(dev);
 264        struct spi_master *master = hw->bitbang.master;
 265
 266        spi_bitbang_stop(&hw->bitbang);
 267        spi_master_put(master);
 268        return 0;
 269}
 270
 271#ifdef CONFIG_OF
 272static const struct of_device_id altera_spi_match[] = {
 273        { .compatible = "ALTR,spi-1.0", },
 274        { .compatible = "altr,spi-1.0", },
 275        {},
 276};
 277MODULE_DEVICE_TABLE(of, altera_spi_match);
 278#endif /* CONFIG_OF */
 279
 280static struct platform_driver altera_spi_driver = {
 281        .probe = altera_spi_probe,
 282        .remove = altera_spi_remove,
 283        .driver = {
 284                .name = DRV_NAME,
 285                .owner = THIS_MODULE,
 286                .pm = NULL,
 287                .of_match_table = of_match_ptr(altera_spi_match),
 288        },
 289};
 290module_platform_driver(altera_spi_driver);
 291
 292MODULE_DESCRIPTION("Altera SPI driver");
 293MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
 294MODULE_LICENSE("GPL");
 295MODULE_ALIAS("platform:" DRV_NAME);
 296
Hosted by Missing Link Electronics. The original LXR software by the LXR community, this experimental version by lxr@linux.no.