drivers/spi/spi-oc-tiny.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * OpenCores tiny SPI master driver
   4  *
   5  * http://opencores.org/project,tiny_spi
   6  *
   7  * Copyright (C) 2011 Thomas Chou <thomas@wytron.com.tw>
   8  *
   9  * Based on spi_s3c24xx.c, which is:
  10  * Copyright (c) 2006 Ben Dooks
  11  * Copyright (c) 2006 Simtec Electronics
  12  *      Ben Dooks <ben@simtec.co.uk>
  13  */
  14
  15 #include <linux/interrupt.h>
  16 #include <linux/errno.h>
  17 #include <linux/module.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/spi/spi.h>
  20 #include <linux/spi/spi_bitbang.h>
  21 #include <linux/spi/spi_oc_tiny.h>
  22 #include <linux/io.h>
  23 #include <linux/of.h>
  24
  25 #define DRV_NAME "spi_oc_tiny"
  26
  27 #define TINY_SPI_RXDATA 0
  28 #define TINY_SPI_TXDATA 4
  29 #define TINY_SPI_STATUS 8
  30 #define TINY_SPI_CONTROL 12
  31 #define TINY_SPI_BAUD 16
  32
  33 #define TINY_SPI_STATUS_TXE 0x1
  34 #define TINY_SPI_STATUS_TXR 0x2
  35
  36 struct tiny_spi {
  37         /* bitbang has to be first */
  38         struct spi_bitbang bitbang;
  39         struct completion done;
  40
  41         void __iomem *base;
  42         int irq;
  43         unsigned int freq;
  44         unsigned int baudwidth;
  45         unsigned int baud;
  46         unsigned int speed_hz;
  47         unsigned int mode;
  48         unsigned int len;
  49         unsigned int txc, rxc;
  50         const u8 *txp;
  51         u8 *rxp;
  52 };
  53
  54 static inline struct tiny_spi *tiny_spi_to_hw(struct spi_device *sdev)
  55 {
  56         return spi_master_get_devdata(sdev->master);
  57 }
  58
  59 static unsigned int tiny_spi_baud(struct spi_device *spi, unsigned int hz)
  60 {
  61         struct tiny_spi *hw = tiny_spi_to_hw(spi);
  62
  63         return min(DIV_ROUND_UP(hw->freq, hz * 2), (1U << hw->baudwidth)) - 1;
  64 }
  65
  66 static int tiny_spi_setup_transfer(struct spi_device *spi,
  67                                    struct spi_transfer *t)
  68 {
  69         struct tiny_spi *hw = tiny_spi_to_hw(spi);
  70         unsigned int baud = hw->baud;
  71
  72         if (t) {
  73                 if (t->speed_hz && t->speed_hz != hw->speed_hz)
  74                         baud = tiny_spi_baud(spi, t->speed_hz);
  75         }
  76         writel(baud, hw->base + TINY_SPI_BAUD);
  77         writel(hw->mode, hw->base + TINY_SPI_CONTROL);
  78         return 0;
  79 }
  80
  81 static int tiny_spi_setup(struct spi_device *spi)
  82 {
  83         struct tiny_spi *hw = tiny_spi_to_hw(spi);
  84
  85         if (spi->max_speed_hz != hw->speed_hz) {
  86                 hw->speed_hz = spi->max_speed_hz;
  87                 hw->baud = tiny_spi_baud(spi, hw->speed_hz);
  88         }
  89         hw->mode = spi->mode & (SPI_CPOL | SPI_CPHA);
  90         return 0;
  91 }
  92
  93 static inline void tiny_spi_wait_txr(struct tiny_spi *hw)
  94 {
  95         while (!(readb(hw->base + TINY_SPI_STATUS) &
  96                  TINY_SPI_STATUS_TXR))
  97                 cpu_relax();
  98 }
  99
 100 static inline void tiny_spi_wait_txe(struct tiny_spi *hw)
 101 {
 102         while (!(readb(hw->base + TINY_SPI_STATUS) &
 103                  TINY_SPI_STATUS_TXE))
 104                 cpu_relax();
 105 }
 106
 107 static int tiny_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t)
 108 {
 109         struct tiny_spi *hw = tiny_spi_to_hw(spi);
 110         const u8 *txp = t->tx_buf;
 111         u8 *rxp = t->rx_buf;
 112         unsigned int i;
 113
 114         if (hw->irq >= 0) {
 115                 /* use interrupt driven data transfer */
 116                 hw->len = t->len;
 117                 hw->txp = t->tx_buf;
 118                 hw->rxp = t->rx_buf;
 119                 hw->txc = 0;
 120                 hw->rxc = 0;
 121
 122                 /* send the first byte */
 123                 if (t->len > 1) {
 124                         writeb(hw->txp ? *hw->txp++ : 0,
 125                                hw->base + TINY_SPI_TXDATA);
 126                         hw->txc++;
 127                         writeb(hw->txp ? *hw->txp++ : 0,
 128                                hw->base + TINY_SPI_TXDATA);
 129                         hw->txc++;
 130                         writeb(TINY_SPI_STATUS_TXR, hw->base + TINY_SPI_STATUS);
 131                 } else {
 132                         writeb(hw->txp ? *hw->txp++ : 0,
 133                                hw->base + TINY_SPI_TXDATA);
 134                         hw->txc++;
 135                         writeb(TINY_SPI_STATUS_TXE, hw->base + TINY_SPI_STATUS);
 136                 }
 137
 138                 wait_for_completion(&hw->done);
 139         } else {
 140                 /* we need to tighten the transfer loop */
 141                 writeb(txp ? *txp++ : 0, hw->base + TINY_SPI_TXDATA);
 142                 for (i = 1; i < t->len; i++) {
 143                         writeb(txp ? *txp++ : 0, hw->base + TINY_SPI_TXDATA);
 144
 145                         if (rxp || (i != t->len - 1))
 146                                 tiny_spi_wait_txr(hw);
 147                         if (rxp)
 148                                 *rxp++ = readb(hw->base + TINY_SPI_TXDATA);
 149                 }
 150                 tiny_spi_wait_txe(hw);
 151                 if (rxp)
 152                         *rxp++ = readb(hw->base + TINY_SPI_RXDATA);
 153         }
 154
 155         return t->len;
 156 }
 157
 158 static irqreturn_t tiny_spi_irq(int irq, void *dev)
 159 {
 160         struct tiny_spi *hw = dev;
 161
 162         writeb(0, hw->base + TINY_SPI_STATUS);
 163         if (hw->rxc + 1 == hw->len) {
 164                 if (hw->rxp)
 165                         *hw->rxp++ = readb(hw->base + TINY_SPI_RXDATA);
 166                 hw->rxc++;
 167                 complete(&hw->done);
 168         } else {
 169                 if (hw->rxp)
 170                         *hw->rxp++ = readb(hw->base + TINY_SPI_TXDATA);
 171                 hw->rxc++;
 172                 if (hw->txc < hw->len) {
 173                         writeb(hw->txp ? *hw->txp++ : 0,
 174                                hw->base + TINY_SPI_TXDATA);
 175                         hw->txc++;
 176                         writeb(TINY_SPI_STATUS_TXR,
 177                                hw->base + TINY_SPI_STATUS);
 178                 } else {
 179                         writeb(TINY_SPI_STATUS_TXE,
 180                                hw->base + TINY_SPI_STATUS);
 181                 }
 182         }
 183         return IRQ_HANDLED;
 184 }
 185
 186 #ifdef CONFIG_OF
 187 #include <linux/of_gpio.h>
 188
 189 static int tiny_spi_of_probe(struct platform_device *pdev)
 190 {
 191         struct tiny_spi *hw = platform_get_drvdata(pdev);
 192         struct device_node *np = pdev->dev.of_node;
 193         u32 val;
 194
 195         if (!np)
 196                 return 0;
 197         hw->bitbang.master->dev.of_node = pdev->dev.of_node;
 198         if (!of_property_read_u32(np, "clock-frequency", &val))
 199                 hw->freq = val;
 200         if (!of_property_read_u32(np, "baud-width", &val))
 201                 hw->baudwidth = val;
 202         return 0;
 203 }
 204 #else /* !CONFIG_OF */
 205 static int tiny_spi_of_probe(struct platform_device *pdev)
 206 {
 207         return 0;
 208 }
 209 #endif /* CONFIG_OF */
 210
 211 static int tiny_spi_probe(struct platform_device *pdev)
 212 {
 213         struct tiny_spi_platform_data *platp = dev_get_platdata(&pdev->dev);
 214         struct tiny_spi *hw;
 215         struct spi_master *master;
 216         int err = -ENODEV;
 217
 218         master = spi_alloc_master(&pdev->dev, sizeof(struct tiny_spi));
 219         if (!master)
 220                 return err;
 221
 222         /* setup the master state. */
 223         master->bus_num = pdev->id;
 224         master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
 225         master->setup = tiny_spi_setup;
 226         master->use_gpio_descriptors = true;
 227
 228         hw = spi_master_get_devdata(master);
 229         platform_set_drvdata(pdev, hw);
 230
 231         /* setup the state for the bitbang driver */
 232         hw->bitbang.master = master;
 233         hw->bitbang.setup_transfer = tiny_spi_setup_transfer;
 234         hw->bitbang.txrx_bufs = tiny_spi_txrx_bufs;
 235
 236         /* find and map our resources */
 237         hw->base = devm_platform_ioremap_resource(pdev, 0);
 238         if (IS_ERR(hw->base)) {
 239                 err = PTR_ERR(hw->base);
 240                 goto exit;
 241         }
 242         /* irq is optional */
 243         hw->irq = platform_get_irq(pdev, 0);
 244         if (hw->irq >= 0) {
 245                 init_completion(&hw->done);
 246                 err = devm_request_irq(&pdev->dev, hw->irq, tiny_spi_irq, 0,
 247                                        pdev->name, hw);
 248                 if (err)
 249                         goto exit;
 250         }
 251         /* find platform data */
 252         if (platp) {
 253                 hw->freq = platp->freq;
 254                 hw->baudwidth = platp->baudwidth;
 255         } else {
 256                 err = tiny_spi_of_probe(pdev);
 257                 if (err)
 258                         goto exit;
 259         }
 260
 261         /* register our spi controller */
 262         err = spi_bitbang_start(&hw->bitbang);
 263         if (err)
 264                 goto exit;
 265         dev_info(&pdev->dev, "base %p, irq %d\n", hw->base, hw->irq);
 266
 267         return 0;
 268
 269 exit:
 270         spi_master_put(master);
 271         return err;
 272 }
 273
 274 static int tiny_spi_remove(struct platform_device *pdev)
 275 {
 276         struct tiny_spi *hw = platform_get_drvdata(pdev);
 277         struct spi_master *master = hw->bitbang.master;
 278
 279         spi_bitbang_stop(&hw->bitbang);
 280         spi_master_put(master);
 281         return 0;
 282 }
 283
 284 #ifdef CONFIG_OF
 285 static const struct of_device_id tiny_spi_match[] = {
 286         { .compatible = "opencores,tiny-spi-rtlsvn2", },
 287         {},
 288 };
 289 MODULE_DEVICE_TABLE(of, tiny_spi_match);
 290 #endif /* CONFIG_OF */
 291
 292 static struct platform_driver tiny_spi_driver = {
 293         .probe = tiny_spi_probe,
 294         .remove = tiny_spi_remove,
 295         .driver = {
 296                 .name = DRV_NAME,
 297                 .pm = NULL,
 298                 .of_match_table = of_match_ptr(tiny_spi_match),
 299         },
 300 };
 301 module_platform_driver(tiny_spi_driver);
 302
 303 MODULE_DESCRIPTION("OpenCores tiny SPI driver");
 304 MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
 305 MODULE_LICENSE("GPL");
 306 MODULE_ALIAS("platform:" DRV_NAME);