drivers/spi/spi-sun6i.c

   1 /*
   2  * Copyright (C) 2012 - 2014 Allwinner Tech
   3  * Pan Nan <pannan@allwinnertech.com>
   4  *
   5  * Copyright (C) 2014 Maxime Ripard
   6  * Maxime Ripard <maxime.ripard@free-electrons.com>
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License as
  10  * published by the Free Software Foundation; either version 2 of
  11  * the License, or (at your option) any later version.
  12  */
  13
  14 #include <linux/clk.h>
  15 #include <linux/delay.h>
  16 #include <linux/device.h>
  17 #include <linux/interrupt.h>
  18 #include <linux/io.h>
  19 #include <linux/module.h>
  20 #include <linux/platform_device.h>
  21 #include <linux/pm_runtime.h>
  22 #include <linux/reset.h>
  23 #include <linux/workqueue.h>
  24
  25 #include <linux/spi/spi.h>
  26
  27 #define SUN6I_FIFO_DEPTH                128
  28
  29 #define SUN6I_GBL_CTL_REG               0x04
  30 #define SUN6I_GBL_CTL_BUS_ENABLE                BIT(0)
  31 #define SUN6I_GBL_CTL_MASTER                    BIT(1)
  32 #define SUN6I_GBL_CTL_TP                        BIT(7)
  33 #define SUN6I_GBL_CTL_RST                       BIT(31)
  34
  35 #define SUN6I_TFR_CTL_REG               0x08
  36 #define SUN6I_TFR_CTL_CPHA                      BIT(0)
  37 #define SUN6I_TFR_CTL_CPOL                      BIT(1)
  38 #define SUN6I_TFR_CTL_SPOL                      BIT(2)
  39 #define SUN6I_TFR_CTL_CS_MASK                   0x30
  40 #define SUN6I_TFR_CTL_CS(cs)                    (((cs) << 4) & SUN6I_TFR_CTL_CS_MASK)
  41 #define SUN6I_TFR_CTL_CS_MANUAL                 BIT(6)
  42 #define SUN6I_TFR_CTL_CS_LEVEL                  BIT(7)
  43 #define SUN6I_TFR_CTL_DHB                       BIT(8)
  44 #define SUN6I_TFR_CTL_FBS                       BIT(12)
  45 #define SUN6I_TFR_CTL_XCH                       BIT(31)
  46
  47 #define SUN6I_INT_CTL_REG               0x10
  48 #define SUN6I_INT_CTL_RF_OVF                    BIT(8)
  49 #define SUN6I_INT_CTL_TC                        BIT(12)
  50
  51 #define SUN6I_INT_STA_REG               0x14
  52
  53 #define SUN6I_FIFO_CTL_REG              0x18
  54 #define SUN6I_FIFO_CTL_RF_RST                   BIT(15)
  55 #define SUN6I_FIFO_CTL_TF_RST                   BIT(31)
  56
  57 #define SUN6I_FIFO_STA_REG              0x1c
  58 #define SUN6I_FIFO_STA_RF_CNT_MASK              0x7f
  59 #define SUN6I_FIFO_STA_RF_CNT_BITS              0
  60 #define SUN6I_FIFO_STA_TF_CNT_MASK              0x7f
  61 #define SUN6I_FIFO_STA_TF_CNT_BITS              16
  62
  63 #define SUN6I_CLK_CTL_REG               0x24
  64 #define SUN6I_CLK_CTL_CDR2_MASK                 0xff
  65 #define SUN6I_CLK_CTL_CDR2(div)                 (((div) & SUN6I_CLK_CTL_CDR2_MASK) << 0)
  66 #define SUN6I_CLK_CTL_CDR1_MASK                 0xf
  67 #define SUN6I_CLK_CTL_CDR1(div)                 (((div) & SUN6I_CLK_CTL_CDR1_MASK) << 8)
  68 #define SUN6I_CLK_CTL_DRS                       BIT(12)
  69
  70 #define SUN6I_BURST_CNT_REG             0x30
  71 #define SUN6I_BURST_CNT(cnt)                    ((cnt) & 0xffffff)
  72
  73 #define SUN6I_XMIT_CNT_REG              0x34
  74 #define SUN6I_XMIT_CNT(cnt)                     ((cnt) & 0xffffff)
  75
  76 #define SUN6I_BURST_CTL_CNT_REG         0x38
  77 #define SUN6I_BURST_CTL_CNT_STC(cnt)            ((cnt) & 0xffffff)
  78
  79 #define SUN6I_TXDATA_REG                0x200
  80 #define SUN6I_RXDATA_REG                0x300
  81
  82 struct sun6i_spi {
  83         struct spi_master       *master;
  84         void __iomem            *base_addr;
  85         struct clk              *hclk;
  86         struct clk              *mclk;
  87         struct reset_control    *rstc;
  88
  89         struct completion       done;
  90
  91         const u8                *tx_buf;
  92         u8                      *rx_buf;
  93         int                     len;
  94 };
  95
  96 static inline u32 sun6i_spi_read(struct sun6i_spi *sspi, u32 reg)
  97 {
  98         return readl(sspi->base_addr + reg);
  99 }
 100
 101 static inline void sun6i_spi_write(struct sun6i_spi *sspi, u32 reg, u32 value)
 102 {
 103         writel(value, sspi->base_addr + reg);
 104 }
 105
 106 static inline void sun6i_spi_drain_fifo(struct sun6i_spi *sspi, int len)
 107 {
 108         u32 reg, cnt;
 109         u8 byte;
 110
 111         /* See how much data is available */
 112         reg = sun6i_spi_read(sspi, SUN6I_FIFO_STA_REG);
 113         reg &= SUN6I_FIFO_STA_RF_CNT_MASK;
 114         cnt = reg >> SUN6I_FIFO_STA_RF_CNT_BITS;
 115
 116         if (len > cnt)
 117                 len = cnt;
 118
 119         while (len--) {
 120                 byte = readb(sspi->base_addr + SUN6I_RXDATA_REG);
 121                 if (sspi->rx_buf)
 122                         *sspi->rx_buf++ = byte;
 123         }
 124 }
 125
 126 static inline void sun6i_spi_fill_fifo(struct sun6i_spi *sspi, int len)
 127 {
 128         u8 byte;
 129
 130         if (len > sspi->len)
 131                 len = sspi->len;
 132
 133         while (len--) {
 134                 byte = sspi->tx_buf ? *sspi->tx_buf++ : 0;
 135                 writeb(byte, sspi->base_addr + SUN6I_TXDATA_REG);
 136                 sspi->len--;
 137         }
 138 }
 139
 140 static void sun6i_spi_set_cs(struct spi_device *spi, bool enable)
 141 {
 142         struct sun6i_spi *sspi = spi_master_get_devdata(spi->master);
 143         u32 reg;
 144
 145         reg = sun6i_spi_read(sspi, SUN6I_TFR_CTL_REG);
 146         reg &= ~SUN6I_TFR_CTL_CS_MASK;
 147         reg |= SUN6I_TFR_CTL_CS(spi->chip_select);
 148
 149         if (enable)
 150                 reg |= SUN6I_TFR_CTL_CS_LEVEL;
 151         else
 152                 reg &= ~SUN6I_TFR_CTL_CS_LEVEL;
 153
 154         sun6i_spi_write(sspi, SUN6I_TFR_CTL_REG, reg);
 155 }
 156
 157
 158 static int sun6i_spi_transfer_one(struct spi_master *master,
 159                                   struct spi_device *spi,
 160                                   struct spi_transfer *tfr)
 161 {
 162         struct sun6i_spi *sspi = spi_master_get_devdata(master);
 163         unsigned int mclk_rate, div, timeout;
 164         unsigned int tx_len = 0;
 165         int ret = 0;
 166         u32 reg;
 167
 168         /* We don't support transfer larger than the FIFO */
 169         if (tfr->len > SUN6I_FIFO_DEPTH)
 170                 return -EINVAL;
 171
 172         reinit_completion(&sspi->done);
 173         sspi->tx_buf = tfr->tx_buf;
 174         sspi->rx_buf = tfr->rx_buf;
 175         sspi->len = tfr->len;
 176
 177         /* Clear pending interrupts */
 178         sun6i_spi_write(sspi, SUN6I_INT_STA_REG, ~0);
 179
 180         /* Reset FIFO */
 181         sun6i_spi_write(sspi, SUN6I_FIFO_CTL_REG,
 182                         SUN6I_FIFO_CTL_RF_RST | SUN6I_FIFO_CTL_TF_RST);
 183
 184         /*
 185          * Setup the transfer control register: Chip Select,
 186          * polarities, etc.
 187          */
 188         reg = sun6i_spi_read(sspi, SUN6I_TFR_CTL_REG);
 189
 190         if (spi->mode & SPI_CPOL)
 191                 reg |= SUN6I_TFR_CTL_CPOL;
 192         else
 193                 reg &= ~SUN6I_TFR_CTL_CPOL;
 194
 195         if (spi->mode & SPI_CPHA)
 196                 reg |= SUN6I_TFR_CTL_CPHA;
 197         else
 198                 reg &= ~SUN6I_TFR_CTL_CPHA;
 199
 200         if (spi->mode & SPI_LSB_FIRST)
 201                 reg |= SUN6I_TFR_CTL_FBS;
 202         else
 203                 reg &= ~SUN6I_TFR_CTL_FBS;
 204
 205         /*
 206          * If it's a TX only transfer, we don't want to fill the RX
 207          * FIFO with bogus data
 208          */
 209         if (sspi->rx_buf)
 210                 reg &= ~SUN6I_TFR_CTL_DHB;
 211         else
 212                 reg |= SUN6I_TFR_CTL_DHB;
 213
 214         /* We want to control the chip select manually */
 215         reg |= SUN6I_TFR_CTL_CS_MANUAL;
 216
 217         sun6i_spi_write(sspi, SUN6I_TFR_CTL_REG, reg);
 218
 219         /* Ensure that we have a parent clock fast enough */
 220         mclk_rate = clk_get_rate(sspi->mclk);
 221         if (mclk_rate < (2 * spi->max_speed_hz)) {
 222                 clk_set_rate(sspi->mclk, 2 * spi->max_speed_hz);
 223                 mclk_rate = clk_get_rate(sspi->mclk);
 224         }
 225
 226         /*
 227          * Setup clock divider.
 228          *
 229          * We have two choices there. Either we can use the clock
 230          * divide rate 1, which is calculated thanks to this formula:
 231          * SPI_CLK = MOD_CLK / (2 ^ cdr)
 232          * Or we can use CDR2, which is calculated with the formula:
 233          * SPI_CLK = MOD_CLK / (2 * (cdr + 1))
 234          * Wether we use the former or the latter is set through the
 235          * DRS bit.
 236          *
 237          * First try CDR2, and if we can't reach the expected
 238          * frequency, fall back to CDR1.
 239          */
 240         div = mclk_rate / (2 * spi->max_speed_hz);
 241         if (div <= (SUN6I_CLK_CTL_CDR2_MASK + 1)) {
 242                 if (div > 0)
 243                         div--;
 244
 245                 reg = SUN6I_CLK_CTL_CDR2(div) | SUN6I_CLK_CTL_DRS;
 246         } else {
 247                 div = ilog2(mclk_rate) - ilog2(spi->max_speed_hz);
 248                 reg = SUN6I_CLK_CTL_CDR1(div);
 249         }
 250
 251         sun6i_spi_write(sspi, SUN6I_CLK_CTL_REG, reg);
 252
 253         /* Setup the transfer now... */
 254         if (sspi->tx_buf)
 255                 tx_len = tfr->len;
 256
 257         /* Setup the counters */
 258         sun6i_spi_write(sspi, SUN6I_BURST_CNT_REG, SUN6I_BURST_CNT(tfr->len));
 259         sun6i_spi_write(sspi, SUN6I_XMIT_CNT_REG, SUN6I_XMIT_CNT(tx_len));
 260         sun6i_spi_write(sspi, SUN6I_BURST_CTL_CNT_REG,
 261                         SUN6I_BURST_CTL_CNT_STC(tx_len));
 262
 263         /* Fill the TX FIFO */
 264         sun6i_spi_fill_fifo(sspi, SUN6I_FIFO_DEPTH);
 265
 266         /* Enable the interrupts */
 267         sun6i_spi_write(sspi, SUN6I_INT_CTL_REG, SUN6I_INT_CTL_TC);
 268
 269         /* Start the transfer */
 270         reg = sun6i_spi_read(sspi, SUN6I_TFR_CTL_REG);
 271         sun6i_spi_write(sspi, SUN6I_TFR_CTL_REG, reg | SUN6I_TFR_CTL_XCH);
 272
 273         timeout = wait_for_completion_timeout(&sspi->done,
 274                                               msecs_to_jiffies(1000));
 275         if (!timeout) {
 276                 ret = -ETIMEDOUT;
 277                 goto out;
 278         }
 279
 280         sun6i_spi_drain_fifo(sspi, SUN6I_FIFO_DEPTH);
 281
 282 out:
 283         sun6i_spi_write(sspi, SUN6I_INT_CTL_REG, 0);
 284
 285         return ret;
 286 }
 287
 288 static irqreturn_t sun6i_spi_handler(int irq, void *dev_id)
 289 {
 290         struct sun6i_spi *sspi = dev_id;
 291         u32 status = sun6i_spi_read(sspi, SUN6I_INT_STA_REG);
 292
 293         /* Transfer complete */
 294         if (status & SUN6I_INT_CTL_TC) {
 295                 sun6i_spi_write(sspi, SUN6I_INT_STA_REG, SUN6I_INT_CTL_TC);
 296                 complete(&sspi->done);
 297                 return IRQ_HANDLED;
 298         }
 299
 300         return IRQ_NONE;
 301 }
 302
 303 static int sun6i_spi_runtime_resume(struct device *dev)
 304 {
 305         struct spi_master *master = dev_get_drvdata(dev);
 306         struct sun6i_spi *sspi = spi_master_get_devdata(master);
 307         int ret;
 308
 309         ret = clk_prepare_enable(sspi->hclk);
 310         if (ret) {
 311                 dev_err(dev, "Couldn't enable AHB clock\n");
 312                 goto out;
 313         }
 314
 315         ret = clk_prepare_enable(sspi->mclk);
 316         if (ret) {
 317                 dev_err(dev, "Couldn't enable module clock\n");
 318                 goto err;
 319         }
 320
 321         ret = reset_control_deassert(sspi->rstc);
 322         if (ret) {
 323                 dev_err(dev, "Couldn't deassert the device from reset\n");
 324                 goto err2;
 325         }
 326
 327         sun6i_spi_write(sspi, SUN6I_GBL_CTL_REG,
 328                         SUN6I_GBL_CTL_BUS_ENABLE | SUN6I_GBL_CTL_MASTER | SUN6I_GBL_CTL_TP);
 329
 330         return 0;
 331
 332 err2:
 333         clk_disable_unprepare(sspi->mclk);
 334 err:
 335         clk_disable_unprepare(sspi->hclk);
 336 out:
 337         return ret;
 338 }
 339
 340 static int sun6i_spi_runtime_suspend(struct device *dev)
 341 {
 342         struct spi_master *master = dev_get_drvdata(dev);
 343         struct sun6i_spi *sspi = spi_master_get_devdata(master);
 344
 345         reset_control_assert(sspi->rstc);
 346         clk_disable_unprepare(sspi->mclk);
 347         clk_disable_unprepare(sspi->hclk);
 348
 349         return 0;
 350 }
 351
 352 static int sun6i_spi_probe(struct platform_device *pdev)
 353 {
 354         struct spi_master *master;
 355         struct sun6i_spi *sspi;
 356         struct resource *res;
 357         int ret = 0, irq;
 358
 359         master = spi_alloc_master(&pdev->dev, sizeof(struct sun6i_spi));
 360         if (!master) {
 361                 dev_err(&pdev->dev, "Unable to allocate SPI Master\n");
 362                 return -ENOMEM;
 363         }
 364
 365         platform_set_drvdata(pdev, master);
 366         sspi = spi_master_get_devdata(master);
 367
 368         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 369         sspi->base_addr = devm_ioremap_resource(&pdev->dev, res);
 370         if (IS_ERR(sspi->base_addr)) {
 371                 ret = PTR_ERR(sspi->base_addr);
 372                 goto err_free_master;
 373         }
 374
 375         irq = platform_get_irq(pdev, 0);
 376         if (irq < 0) {
 377                 dev_err(&pdev->dev, "No spi IRQ specified\n");
 378                 ret = -ENXIO;
 379                 goto err_free_master;
 380         }
 381
 382         ret = devm_request_irq(&pdev->dev, irq, sun6i_spi_handler,
 383                                0, "sun6i-spi", sspi);
 384         if (ret) {
 385                 dev_err(&pdev->dev, "Cannot request IRQ\n");
 386                 goto err_free_master;
 387         }
 388
 389         sspi->master = master;
 390         master->set_cs = sun6i_spi_set_cs;
 391         master->transfer_one = sun6i_spi_transfer_one;
 392         master->num_chipselect = 4;
 393         master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH | SPI_LSB_FIRST;
 394         master->bits_per_word_mask = SPI_BPW_MASK(8);
 395         master->dev.of_node = pdev->dev.of_node;
 396         master->auto_runtime_pm = true;
 397
 398         sspi->hclk = devm_clk_get(&pdev->dev, "ahb");
 399         if (IS_ERR(sspi->hclk)) {
 400                 dev_err(&pdev->dev, "Unable to acquire AHB clock\n");
 401                 ret = PTR_ERR(sspi->hclk);
 402                 goto err_free_master;
 403         }
 404
 405         sspi->mclk = devm_clk_get(&pdev->dev, "mod");
 406         if (IS_ERR(sspi->mclk)) {
 407                 dev_err(&pdev->dev, "Unable to acquire module clock\n");
 408                 ret = PTR_ERR(sspi->mclk);
 409                 goto err_free_master;
 410         }
 411
 412         init_completion(&sspi->done);
 413
 414         sspi->rstc = devm_reset_control_get(&pdev->dev, NULL);
 415         if (IS_ERR(sspi->rstc)) {
 416                 dev_err(&pdev->dev, "Couldn't get reset controller\n");
 417                 ret = PTR_ERR(sspi->rstc);
 418                 goto err_free_master;
 419         }
 420
 421         /*
 422          * This wake-up/shutdown pattern is to be able to have the
 423          * device woken up, even if runtime_pm is disabled
 424          */
 425         ret = sun6i_spi_runtime_resume(&pdev->dev);
 426         if (ret) {
 427                 dev_err(&pdev->dev, "Couldn't resume the device\n");
 428                 goto err_free_master;
 429         }
 430
 431         pm_runtime_set_active(&pdev->dev);
 432         pm_runtime_enable(&pdev->dev);
 433         pm_runtime_idle(&pdev->dev);
 434
 435         ret = devm_spi_register_master(&pdev->dev, master);
 436         if (ret) {
 437                 dev_err(&pdev->dev, "cannot register SPI master\n");
 438                 goto err_pm_disable;
 439         }
 440
 441         return 0;
 442
 443 err_pm_disable:
 444         pm_runtime_disable(&pdev->dev);
 445         sun6i_spi_runtime_suspend(&pdev->dev);
 446 err_free_master:
 447         spi_master_put(master);
 448         return ret;
 449 }
 450
 451 static int sun6i_spi_remove(struct platform_device *pdev)
 452 {
 453         pm_runtime_disable(&pdev->dev);
 454
 455         return 0;
 456 }
 457
 458 static const struct of_device_id sun6i_spi_match[] = {
 459         { .compatible = "allwinner,sun6i-a31-spi", },
 460         {}
 461 };
 462 MODULE_DEVICE_TABLE(of, sun6i_spi_match);
 463
 464 static const struct dev_pm_ops sun6i_spi_pm_ops = {
 465         .runtime_resume         = sun6i_spi_runtime_resume,
 466         .runtime_suspend        = sun6i_spi_runtime_suspend,
 467 };
 468
 469 static struct platform_driver sun6i_spi_driver = {
 470         .probe  = sun6i_spi_probe,
 471         .remove = sun6i_spi_remove,
 472         .driver = {
 473                 .name           = "sun6i-spi",
 474                 .owner          = THIS_MODULE,
 475                 .of_match_table = sun6i_spi_match,
 476                 .pm             = &sun6i_spi_pm_ops,
 477         },
 478 };
 479 module_platform_driver(sun6i_spi_driver);
 480
 481 MODULE_AUTHOR("Pan Nan <pannan@allwinnertech.com>");
 482 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
 483 MODULE_DESCRIPTION("Allwinner A31 SPI controller driver");
 484 MODULE_LICENSE("GPL");