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