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/io.h>
  22 #include <linux/of.h>
  23
  24 #define DRV_NAME "spi_altera"
  25
  26 #define ALTERA_SPI_RXDATA       0
  27 #define ALTERA_SPI_TXDATA       4
  28 #define ALTERA_SPI_STATUS       8
  29 #define ALTERA_SPI_CONTROL      12
  30 #define ALTERA_SPI_SLAVE_SEL    20
  31
  32 #define ALTERA_SPI_STATUS_ROE_MSK       0x8
  33 #define ALTERA_SPI_STATUS_TOE_MSK       0x10
  34 #define ALTERA_SPI_STATUS_TMT_MSK       0x20
  35 #define ALTERA_SPI_STATUS_TRDY_MSK      0x40
  36 #define ALTERA_SPI_STATUS_RRDY_MSK      0x80
  37 #define ALTERA_SPI_STATUS_E_MSK         0x100
  38
  39 #define ALTERA_SPI_CONTROL_IROE_MSK     0x8
  40 #define ALTERA_SPI_CONTROL_ITOE_MSK     0x10
  41 #define ALTERA_SPI_CONTROL_ITRDY_MSK    0x40
  42 #define ALTERA_SPI_CONTROL_IRRDY_MSK    0x80
  43 #define ALTERA_SPI_CONTROL_IE_MSK       0x100
  44 #define ALTERA_SPI_CONTROL_SSO_MSK      0x400
  45
  46 struct altera_spi {
  47         void __iomem *base;
  48         int irq;
  49         int len;
  50         int count;
  51         int bytes_per_word;
  52         unsigned long imr;
  53
  54         /* data buffers */
  55         const unsigned char *tx;
  56         unsigned char *rx;
  57 };
  58
  59 static inline struct altera_spi *altera_spi_to_hw(struct spi_device *sdev)
  60 {
  61         return spi_master_get_devdata(sdev->master);
  62 }
  63
  64 static void altera_spi_set_cs(struct spi_device *spi, bool is_high)
  65 {
  66         struct altera_spi *hw = altera_spi_to_hw(spi);
  67
  68         if (is_high) {
  69                 hw->imr &= ~ALTERA_SPI_CONTROL_SSO_MSK;
  70                 writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
  71                 writel(0, hw->base + ALTERA_SPI_SLAVE_SEL);
  72         } else {
  73                 writel(BIT(spi->chip_select), hw->base + ALTERA_SPI_SLAVE_SEL);
  74                 hw->imr |= ALTERA_SPI_CONTROL_SSO_MSK;
  75                 writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
  76         }
  77 }
  78
  79 static void altera_spi_tx_word(struct altera_spi *hw)
  80 {
  81         unsigned int txd = 0;
  82
  83         if (hw->tx) {
  84                 switch (hw->bytes_per_word) {
  85                 case 1:
  86                         txd = hw->tx[hw->count];
  87                         break;
  88                 case 2:
  89                         txd = (hw->tx[hw->count * 2]
  90                                 | (hw->tx[hw->count * 2 + 1] << 8));
  91                         break;
  92                 }
  93         }
  94
  95         writel(txd, hw->base + ALTERA_SPI_TXDATA);
  96 }
  97
  98 static void altera_spi_rx_word(struct altera_spi *hw)
  99 {
 100         unsigned int rxd;
 101
 102         rxd = readl(hw->base + ALTERA_SPI_RXDATA);
 103         if (hw->rx) {
 104                 switch (hw->bytes_per_word) {
 105                 case 1:
 106                         hw->rx[hw->count] = rxd;
 107                         break;
 108                 case 2:
 109                         hw->rx[hw->count * 2] = rxd;
 110                         hw->rx[hw->count * 2 + 1] = rxd >> 8;
 111                         break;
 112                 }
 113         }
 114
 115         hw->count++;
 116 }
 117
 118 static int altera_spi_txrx(struct spi_master *master,
 119         struct spi_device *spi, struct spi_transfer *t)
 120 {
 121         struct altera_spi *hw = spi_master_get_devdata(master);
 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                 altera_spi_tx_word(hw);
 136         } else {
 137                 while (hw->count < hw->len) {
 138                         altera_spi_tx_word(hw);
 139
 140                         while (!(readl(hw->base + ALTERA_SPI_STATUS) &
 141                                  ALTERA_SPI_STATUS_RRDY_MSK))
 142                                 cpu_relax();
 143
 144                         altera_spi_rx_word(hw);
 145                 }
 146                 spi_finalize_current_transfer(master);
 147         }
 148
 149         return t->len;
 150 }
 151
 152 static irqreturn_t altera_spi_irq(int irq, void *dev)
 153 {
 154         struct spi_master *master = dev;
 155         struct altera_spi *hw = spi_master_get_devdata(master);
 156
 157         altera_spi_rx_word(hw);
 158
 159         if (hw->count < hw->len) {
 160                 altera_spi_tx_word(hw);
 161         } else {
 162                 /* disable receive interrupt */
 163                 hw->imr &= ~ALTERA_SPI_CONTROL_IRRDY_MSK;
 164                 writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
 165
 166                 spi_finalize_current_transfer(master);
 167         }
 168
 169         return IRQ_HANDLED;
 170 }
 171
 172 static int altera_spi_probe(struct platform_device *pdev)
 173 {
 174         struct altera_spi *hw;
 175         struct spi_master *master;
 176         struct resource *res;
 177         int err = -ENODEV;
 178
 179         master = spi_alloc_master(&pdev->dev, sizeof(struct altera_spi));
 180         if (!master)
 181                 return err;
 182
 183         /* setup the master state. */
 184         master->bus_num = pdev->id;
 185         master->num_chipselect = 16;
 186         master->mode_bits = SPI_CS_HIGH;
 187         master->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 16);
 188         master->dev.of_node = pdev->dev.of_node;
 189         master->transfer_one = altera_spi_txrx;
 190         master->set_cs = altera_spi_set_cs;
 191
 192         hw = spi_master_get_devdata(master);
 193
 194         /* find and map our resources */
 195         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 196         hw->base = devm_ioremap_resource(&pdev->dev, res);
 197         if (IS_ERR(hw->base)) {
 198                 err = PTR_ERR(hw->base);
 199                 goto exit;
 200         }
 201         /* program defaults into the registers */
 202         hw->imr = 0;            /* disable spi interrupts */
 203         writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
 204         writel(0, hw->base + ALTERA_SPI_STATUS);        /* clear status reg */
 205         if (readl(hw->base + ALTERA_SPI_STATUS) & ALTERA_SPI_STATUS_RRDY_MSK)
 206                 readl(hw->base + ALTERA_SPI_RXDATA);    /* flush rxdata */
 207         /* irq is optional */
 208         hw->irq = platform_get_irq(pdev, 0);
 209         if (hw->irq >= 0) {
 210                 err = devm_request_irq(&pdev->dev, hw->irq, altera_spi_irq, 0,
 211                                        pdev->name, master);
 212                 if (err)
 213                         goto exit;
 214         }
 215
 216         err = devm_spi_register_master(&pdev->dev, master);
 217         if (err)
 218                 goto exit;
 219         dev_info(&pdev->dev, "base %p, irq %d\n", hw->base, hw->irq);
 220
 221         return 0;
 222 exit:
 223         spi_master_put(master);
 224         return err;
 225 }
 226
 227 #ifdef CONFIG_OF
 228 static const struct of_device_id altera_spi_match[] = {
 229         { .compatible = "ALTR,spi-1.0", },
 230         { .compatible = "altr,spi-1.0", },
 231         {},
 232 };
 233 MODULE_DEVICE_TABLE(of, altera_spi_match);
 234 #endif /* CONFIG_OF */
 235
 236 static struct platform_driver altera_spi_driver = {
 237         .probe = altera_spi_probe,
 238         .driver = {
 239                 .name = DRV_NAME,
 240                 .pm = NULL,
 241                 .of_match_table = of_match_ptr(altera_spi_match),
 242         },
 243 };
 244 module_platform_driver(altera_spi_driver);
 245
 246 MODULE_DESCRIPTION("Altera SPI driver");
 247 MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
 248 MODULE_LICENSE("GPL");
 249 MODULE_ALIAS("platform:" DRV_NAME);