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/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
  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 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
 119 static 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
 172 static 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
 200 static 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;
 256 exit:
 257         spi_master_put(master);
 258         return err;
 259 }
 260
 261 static 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
 272 static const struct of_device_id altera_spi_match[] = {
 273         { .compatible = "ALTR,spi-1.0", },
 274         { .compatible = "altr,spi-1.0", },
 275         {},
 276 };
 277 MODULE_DEVICE_TABLE(of, altera_spi_match);
 278 #endif /* CONFIG_OF */
 279
 280 static struct platform_driver altera_spi_driver = {
 281         .probe = altera_spi_probe,
 282         .remove = altera_spi_remove,
 283         .driver = {
 284                 .name = DRV_NAME,
 285                 .pm = NULL,
 286                 .of_match_table = of_match_ptr(altera_spi_match),
 287         },
 288 };
 289 module_platform_driver(altera_spi_driver);
 290
 291 MODULE_DESCRIPTION("Altera SPI driver");
 292 MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
 293 MODULE_LICENSE("GPL");
 294 MODULE_ALIAS("platform:" DRV_NAME);