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/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
  48 struct 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
  65 static inline struct altera_spi *altera_spi_to_hw(struct spi_device *sdev)
  66 {
  67         return spi_master_get_devdata(sdev->master);
  68 }
  69
  70 static 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
 106 static 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
 120 static 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
 173 static 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
 201 static 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 = 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         /* find platform data */
 249         if (!platp)
 250                 hw->bitbang.master->dev.of_node = pdev->dev.of_node;
 251
 252         /* register our spi controller */
 253         err = spi_bitbang_start(&hw->bitbang);
 254         if (err)
 255                 goto exit;
 256         dev_info(&pdev->dev, "base %p, irq %d\n", hw->base, hw->irq);
 257
 258         return 0;
 259 exit:
 260         spi_master_put(master);
 261         return err;
 262 }
 263
 264 static int altera_spi_remove(struct platform_device *dev)
 265 {
 266         struct altera_spi *hw = platform_get_drvdata(dev);
 267         struct spi_master *master = hw->bitbang.master;
 268
 269         spi_bitbang_stop(&hw->bitbang);
 270         spi_master_put(master);
 271         return 0;
 272 }
 273
 274 #ifdef CONFIG_OF
 275 static const struct of_device_id altera_spi_match[] = {
 276         { .compatible = "ALTR,spi-1.0", },
 277         { .compatible = "altr,spi-1.0", },
 278         {},
 279 };
 280 MODULE_DEVICE_TABLE(of, altera_spi_match);
 281 #endif /* CONFIG_OF */
 282
 283 static struct platform_driver altera_spi_driver = {
 284         .probe = altera_spi_probe,
 285         .remove = altera_spi_remove,
 286         .driver = {
 287                 .name = DRV_NAME,
 288                 .owner = THIS_MODULE,
 289                 .pm = NULL,
 290                 .of_match_table = of_match_ptr(altera_spi_match),
 291         },
 292 };
 293 module_platform_driver(altera_spi_driver);
 294
 295 MODULE_DESCRIPTION("Altera SPI driver");
 296 MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
 297 MODULE_LICENSE("GPL");
 298 MODULE_ALIAS("platform:" DRV_NAME);