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
  24 #include <linux/spi/spi.h>
  25
  26 #define SUN6I_FIFO_DEPTH                128
  27
  28 #define SUN6I_GBL_CTL_REG               0x04
  29 #define SUN6I_GBL_CTL_BUS_ENABLE                BIT(0)
  30 #define SUN6I_GBL_CTL_MASTER                    BIT(1)
  31 #define SUN6I_GBL_CTL_TP                        BIT(7)
  32 #define SUN6I_GBL_CTL_RST                       BIT(31)
  33
  34 #define SUN6I_TFR_CTL_REG               0x08
  35 #define SUN6I_TFR_CTL_CPHA                      BIT(0)
  36 #define SUN6I_TFR_CTL_CPOL                      BIT(1)
  37 #define SUN6I_TFR_CTL_SPOL                      BIT(2)
  38 #define SUN6I_TFR_CTL_CS_MASK                   0x30
  39 #define SUN6I_TFR_CTL_CS(cs)                    (((cs) << 4) & SUN6I_TFR_CTL_CS_MASK)
  40 #define SUN6I_TFR_CTL_CS_MANUAL                 BIT(6)
  41 #define SUN6I_TFR_CTL_CS_LEVEL                  BIT(7)
  42 #define SUN6I_TFR_CTL_DHB                       BIT(8)
  43 #define SUN6I_TFR_CTL_FBS                       BIT(12)
  44 #define SUN6I_TFR_CTL_XCH                       BIT(31)
  45
  46 #define SUN6I_INT_CTL_REG               0x10
  47 #define SUN6I_INT_CTL_RF_OVF                    BIT(8)
  48 #define SUN6I_INT_CTL_TC                        BIT(12)
  49
  50 #define SUN6I_INT_STA_REG               0x14
  51
  52 #define SUN6I_FIFO_CTL_REG              0x18
  53 #define SUN6I_FIFO_CTL_RF_RST                   BIT(15)
  54 #define SUN6I_FIFO_CTL_TF_RST                   BIT(31)
  55
  56 #define SUN6I_FIFO_STA_REG              0x1c
  57 #define SUN6I_FIFO_STA_RF_CNT_MASK              0x7f
  58 #define SUN6I_FIFO_STA_RF_CNT_BITS              0
  59 #define SUN6I_FIFO_STA_TF_CNT_MASK              0x7f
  60 #define SUN6I_FIFO_STA_TF_CNT_BITS              16
  61
  62 #define SUN6I_CLK_CTL_REG               0x24
  63 #define SUN6I_CLK_CTL_CDR2_MASK                 0xff
  64 #define SUN6I_CLK_CTL_CDR2(div)                 (((div) & SUN6I_CLK_CTL_CDR2_MASK) << 0)
  65 #define SUN6I_CLK_CTL_CDR1_MASK                 0xf
  66 #define SUN6I_CLK_CTL_CDR1(div)                 (((div) & SUN6I_CLK_CTL_CDR1_MASK) << 8)
  67 #define SUN6I_CLK_CTL_DRS                       BIT(12)
  68
  69 #define SUN6I_BURST_CNT_REG             0x30
  70 #define SUN6I_BURST_CNT(cnt)                    ((cnt) & 0xffffff)
  71
  72 #define SUN6I_XMIT_CNT_REG              0x34
  73 #define SUN6I_XMIT_CNT(cnt)                     ((cnt) & 0xffffff)
  74
  75 #define SUN6I_BURST_CTL_CNT_REG         0x38
  76 #define SUN6I_BURST_CTL_CNT_STC(cnt)            ((cnt) & 0xffffff)
  77
  78 #define SUN6I_TXDATA_REG                0x200
  79 #define SUN6I_RXDATA_REG                0x300
  80
  81 struct sun6i_spi {
  82         struct spi_master       *master;
  83         void __iomem            *base_addr;
  84         struct clk              *hclk;
  85         struct clk              *mclk;
  86         struct reset_control    *rstc;
  87
  88         struct completion       done;
  89
  90         const u8                *tx_buf;
  91         u8                      *rx_buf;
  92         int                     len;
  93 };
  94
  95 static inline u32 sun6i_spi_read(struct sun6i_spi *sspi, u32 reg)
  96 {
  97         return readl(sspi->base_addr + reg);
  98 }
  99
 100 static inline void sun6i_spi_write(struct sun6i_spi *sspi, u32 reg, u32 value)
 101 {
 102         writel(value, sspi->base_addr + reg);
 103 }
 104
 105 static inline void sun6i_spi_drain_fifo(struct sun6i_spi *sspi, int len)
 106 {
 107         u32 reg, cnt;
 108         u8 byte;
 109
 110         /* See how much data is available */
 111         reg = sun6i_spi_read(sspi, SUN6I_FIFO_STA_REG);
 112         reg &= SUN6I_FIFO_STA_RF_CNT_MASK;
 113         cnt = reg >> SUN6I_FIFO_STA_RF_CNT_BITS;
 114
 115         if (len > cnt)
 116                 len = cnt;
 117
 118         while (len--) {
 119                 byte = readb(sspi->base_addr + SUN6I_RXDATA_REG);
 120                 if (sspi->rx_buf)
 121                         *sspi->rx_buf++ = byte;
 122         }
 123 }
 124
 125 static inline void sun6i_spi_fill_fifo(struct sun6i_spi *sspi, int len)
 126 {
 127         u8 byte;
 128
 129         if (len > sspi->len)
 130                 len = sspi->len;
 131
 132         while (len--) {
 133                 byte = sspi->tx_buf ? *sspi->tx_buf++ : 0;
 134                 writeb(byte, sspi->base_addr + SUN6I_TXDATA_REG);
 135                 sspi->len--;
 136         }
 137 }
 138
 139 static void sun6i_spi_set_cs(struct spi_device *spi, bool enable)
 140 {
 141         struct sun6i_spi *sspi = spi_master_get_devdata(spi->master);
 142         u32 reg;
 143
 144         reg = sun6i_spi_read(sspi, SUN6I_TFR_CTL_REG);
 145         reg &= ~SUN6I_TFR_CTL_CS_MASK;
 146         reg |= SUN6I_TFR_CTL_CS(spi->chip_select);
 147
 148         if (enable)
 149                 reg |= SUN6I_TFR_CTL_CS_LEVEL;
 150         else
 151                 reg &= ~SUN6I_TFR_CTL_CS_LEVEL;
 152
 153         sun6i_spi_write(sspi, SUN6I_TFR_CTL_REG, reg);
 154 }
 155
 156 static size_t sun6i_spi_max_transfer_size(struct spi_device *spi)
 157 {
 158         return SUN6I_FIFO_DEPTH - 1;
 159 }
 160
 161 static int sun6i_spi_transfer_one(struct spi_master *master,
 162                                   struct spi_device *spi,
 163                                   struct spi_transfer *tfr)
 164 {
 165         struct sun6i_spi *sspi = spi_master_get_devdata(master);
 166         unsigned int mclk_rate, div, timeout;
 167         unsigned int start, end, tx_time;
 168         unsigned int tx_len = 0;
 169         int ret = 0;
 170         u32 reg;
 171
 172         /* We don't support transfer larger than the FIFO */
 173         if (tfr->len > SUN6I_FIFO_DEPTH)
 174                 return -EINVAL;
 175
 176         reinit_completion(&sspi->done);
 177         sspi->tx_buf = tfr->tx_buf;
 178         sspi->rx_buf = tfr->rx_buf;
 179         sspi->len = tfr->len;
 180
 181         /* Clear pending interrupts */
 182         sun6i_spi_write(sspi, SUN6I_INT_STA_REG, ~0);
 183
 184         /* Reset FIFO */
 185         sun6i_spi_write(sspi, SUN6I_FIFO_CTL_REG,
 186                         SUN6I_FIFO_CTL_RF_RST | SUN6I_FIFO_CTL_TF_RST);
 187
 188         /*
 189          * Setup the transfer control register: Chip Select,
 190          * polarities, etc.
 191          */
 192         reg = sun6i_spi_read(sspi, SUN6I_TFR_CTL_REG);
 193
 194         if (spi->mode & SPI_CPOL)
 195                 reg |= SUN6I_TFR_CTL_CPOL;
 196         else
 197                 reg &= ~SUN6I_TFR_CTL_CPOL;
 198
 199         if (spi->mode & SPI_CPHA)
 200                 reg |= SUN6I_TFR_CTL_CPHA;
 201         else
 202                 reg &= ~SUN6I_TFR_CTL_CPHA;
 203
 204         if (spi->mode & SPI_LSB_FIRST)
 205                 reg |= SUN6I_TFR_CTL_FBS;
 206         else
 207                 reg &= ~SUN6I_TFR_CTL_FBS;
 208
 209         /*
 210          * If it's a TX only transfer, we don't want to fill the RX
 211          * FIFO with bogus data
 212          */
 213         if (sspi->rx_buf)
 214                 reg &= ~SUN6I_TFR_CTL_DHB;
 215         else
 216                 reg |= SUN6I_TFR_CTL_DHB;
 217
 218         /* We want to control the chip select manually */
 219         reg |= SUN6I_TFR_CTL_CS_MANUAL;
 220
 221         sun6i_spi_write(sspi, SUN6I_TFR_CTL_REG, reg);
 222
 223         /* Ensure that we have a parent clock fast enough */
 224         mclk_rate = clk_get_rate(sspi->mclk);
 225         if (mclk_rate < (2 * tfr->speed_hz)) {
 226                 clk_set_rate(sspi->mclk, 2 * tfr->speed_hz);
 227                 mclk_rate = clk_get_rate(sspi->mclk);
 228         }
 229
 230         /*
 231          * Setup clock divider.
 232          *
 233          * We have two choices there. Either we can use the clock
 234          * divide rate 1, which is calculated thanks to this formula:
 235          * SPI_CLK = MOD_CLK / (2 ^ cdr)
 236          * Or we can use CDR2, which is calculated with the formula:
 237          * SPI_CLK = MOD_CLK / (2 * (cdr + 1))
 238          * Wether we use the former or the latter is set through the
 239          * DRS bit.
 240          *
 241          * First try CDR2, and if we can't reach the expected
 242          * frequency, fall back to CDR1.
 243          */
 244         div = mclk_rate / (2 * tfr->speed_hz);
 245         if (div <= (SUN6I_CLK_CTL_CDR2_MASK + 1)) {
 246                 if (div > 0)
 247                         div--;
 248
 249                 reg = SUN6I_CLK_CTL_CDR2(div) | SUN6I_CLK_CTL_DRS;
 250         } else {
 251                 div = ilog2(mclk_rate) - ilog2(tfr->speed_hz);
 252                 reg = SUN6I_CLK_CTL_CDR1(div);
 253         }
 254
 255         sun6i_spi_write(sspi, SUN6I_CLK_CTL_REG, reg);
 256
 257         /* Setup the transfer now... */
 258         if (sspi->tx_buf)
 259                 tx_len = tfr->len;
 260
 261         /* Setup the counters */
 262         sun6i_spi_write(sspi, SUN6I_BURST_CNT_REG, SUN6I_BURST_CNT(tfr->len));
 263         sun6i_spi_write(sspi, SUN6I_XMIT_CNT_REG, SUN6I_XMIT_CNT(tx_len));
 264         sun6i_spi_write(sspi, SUN6I_BURST_CTL_CNT_REG,
 265                         SUN6I_BURST_CTL_CNT_STC(tx_len));
 266
 267         /* Fill the TX FIFO */
 268         sun6i_spi_fill_fifo(sspi, SUN6I_FIFO_DEPTH);
 269
 270         /* Enable the interrupts */
 271         sun6i_spi_write(sspi, SUN6I_INT_CTL_REG, SUN6I_INT_CTL_TC);
 272
 273         /* Start the transfer */
 274         reg = sun6i_spi_read(sspi, SUN6I_TFR_CTL_REG);
 275         sun6i_spi_write(sspi, SUN6I_TFR_CTL_REG, reg | SUN6I_TFR_CTL_XCH);
 276
 277         tx_time = max(tfr->len * 8 * 2 / (tfr->speed_hz / 1000), 100U);
 278         start = jiffies;
 279         timeout = wait_for_completion_timeout(&sspi->done,
 280                                               msecs_to_jiffies(tx_time));
 281         end = jiffies;
 282         if (!timeout) {
 283                 dev_warn(&master->dev,
 284                          "%s: timeout transferring %u bytes@%iHz for %i(%i)ms",
 285                          dev_name(&spi->dev), tfr->len, tfr->speed_hz,
 286                          jiffies_to_msecs(end - start), tx_time);
 287                 ret = -ETIMEDOUT;
 288                 goto out;
 289         }
 290
 291         sun6i_spi_drain_fifo(sspi, SUN6I_FIFO_DEPTH);
 292
 293 out:
 294         sun6i_spi_write(sspi, SUN6I_INT_CTL_REG, 0);
 295
 296         return ret;
 297 }
 298
 299 static irqreturn_t sun6i_spi_handler(int irq, void *dev_id)
 300 {
 301         struct sun6i_spi *sspi = dev_id;
 302         u32 status = sun6i_spi_read(sspi, SUN6I_INT_STA_REG);
 303
 304         /* Transfer complete */
 305         if (status & SUN6I_INT_CTL_TC) {
 306                 sun6i_spi_write(sspi, SUN6I_INT_STA_REG, SUN6I_INT_CTL_TC);
 307                 complete(&sspi->done);
 308                 return IRQ_HANDLED;
 309         }
 310
 311         return IRQ_NONE;
 312 }
 313
 314 static int sun6i_spi_runtime_resume(struct device *dev)
 315 {
 316         struct spi_master *master = dev_get_drvdata(dev);
 317         struct sun6i_spi *sspi = spi_master_get_devdata(master);
 318         int ret;
 319
 320         ret = clk_prepare_enable(sspi->hclk);
 321         if (ret) {
 322                 dev_err(dev, "Couldn't enable AHB clock\n");
 323                 goto out;
 324         }
 325
 326         ret = clk_prepare_enable(sspi->mclk);
 327         if (ret) {
 328                 dev_err(dev, "Couldn't enable module clock\n");
 329                 goto err;
 330         }
 331
 332         ret = reset_control_deassert(sspi->rstc);
 333         if (ret) {
 334                 dev_err(dev, "Couldn't deassert the device from reset\n");
 335                 goto err2;
 336         }
 337
 338         sun6i_spi_write(sspi, SUN6I_GBL_CTL_REG,
 339                         SUN6I_GBL_CTL_BUS_ENABLE | SUN6I_GBL_CTL_MASTER | SUN6I_GBL_CTL_TP);
 340
 341         return 0;
 342
 343 err2:
 344         clk_disable_unprepare(sspi->mclk);
 345 err:
 346         clk_disable_unprepare(sspi->hclk);
 347 out:
 348         return ret;
 349 }
 350
 351 static int sun6i_spi_runtime_suspend(struct device *dev)
 352 {
 353         struct spi_master *master = dev_get_drvdata(dev);
 354         struct sun6i_spi *sspi = spi_master_get_devdata(master);
 355
 356         reset_control_assert(sspi->rstc);
 357         clk_disable_unprepare(sspi->mclk);
 358         clk_disable_unprepare(sspi->hclk);
 359
 360         return 0;
 361 }
 362
 363 static int sun6i_spi_probe(struct platform_device *pdev)
 364 {
 365         struct spi_master *master;
 366         struct sun6i_spi *sspi;
 367         struct resource *res;
 368         int ret = 0, irq;
 369
 370         master = spi_alloc_master(&pdev->dev, sizeof(struct sun6i_spi));
 371         if (!master) {
 372                 dev_err(&pdev->dev, "Unable to allocate SPI Master\n");
 373                 return -ENOMEM;
 374         }
 375
 376         platform_set_drvdata(pdev, master);
 377         sspi = spi_master_get_devdata(master);
 378
 379         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 380         sspi->base_addr = devm_ioremap_resource(&pdev->dev, res);
 381         if (IS_ERR(sspi->base_addr)) {
 382                 ret = PTR_ERR(sspi->base_addr);
 383                 goto err_free_master;
 384         }
 385
 386         irq = platform_get_irq(pdev, 0);
 387         if (irq < 0) {
 388                 dev_err(&pdev->dev, "No spi IRQ specified\n");
 389                 ret = -ENXIO;
 390                 goto err_free_master;
 391         }
 392
 393         ret = devm_request_irq(&pdev->dev, irq, sun6i_spi_handler,
 394                                0, "sun6i-spi", sspi);
 395         if (ret) {
 396                 dev_err(&pdev->dev, "Cannot request IRQ\n");
 397                 goto err_free_master;
 398         }
 399
 400         sspi->master = master;
 401         master->max_speed_hz = 100 * 1000 * 1000;
 402         master->min_speed_hz = 3 * 1000;
 403         master->set_cs = sun6i_spi_set_cs;
 404         master->transfer_one = sun6i_spi_transfer_one;
 405         master->num_chipselect = 4;
 406         master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH | SPI_LSB_FIRST;
 407         master->bits_per_word_mask = SPI_BPW_MASK(8);
 408         master->dev.of_node = pdev->dev.of_node;
 409         master->auto_runtime_pm = true;
 410         master->max_transfer_size = sun6i_spi_max_transfer_size;
 411
 412         sspi->hclk = devm_clk_get(&pdev->dev, "ahb");
 413         if (IS_ERR(sspi->hclk)) {
 414                 dev_err(&pdev->dev, "Unable to acquire AHB clock\n");
 415                 ret = PTR_ERR(sspi->hclk);
 416                 goto err_free_master;
 417         }
 418
 419         sspi->mclk = devm_clk_get(&pdev->dev, "mod");
 420         if (IS_ERR(sspi->mclk)) {
 421                 dev_err(&pdev->dev, "Unable to acquire module clock\n");
 422                 ret = PTR_ERR(sspi->mclk);
 423                 goto err_free_master;
 424         }
 425
 426         init_completion(&sspi->done);
 427
 428         sspi->rstc = devm_reset_control_get(&pdev->dev, NULL);
 429         if (IS_ERR(sspi->rstc)) {
 430                 dev_err(&pdev->dev, "Couldn't get reset controller\n");
 431                 ret = PTR_ERR(sspi->rstc);
 432                 goto err_free_master;
 433         }
 434
 435         /*
 436          * This wake-up/shutdown pattern is to be able to have the
 437          * device woken up, even if runtime_pm is disabled
 438          */
 439         ret = sun6i_spi_runtime_resume(&pdev->dev);
 440         if (ret) {
 441                 dev_err(&pdev->dev, "Couldn't resume the device\n");
 442                 goto err_free_master;
 443         }
 444
 445         pm_runtime_set_active(&pdev->dev);
 446         pm_runtime_enable(&pdev->dev);
 447         pm_runtime_idle(&pdev->dev);
 448
 449         ret = devm_spi_register_master(&pdev->dev, master);
 450         if (ret) {
 451                 dev_err(&pdev->dev, "cannot register SPI master\n");
 452                 goto err_pm_disable;
 453         }
 454
 455         return 0;
 456
 457 err_pm_disable:
 458         pm_runtime_disable(&pdev->dev);
 459         sun6i_spi_runtime_suspend(&pdev->dev);
 460 err_free_master:
 461         spi_master_put(master);
 462         return ret;
 463 }
 464
 465 static int sun6i_spi_remove(struct platform_device *pdev)
 466 {
 467         pm_runtime_disable(&pdev->dev);
 468
 469         return 0;
 470 }
 471
 472 static const struct of_device_id sun6i_spi_match[] = {
 473         { .compatible = "allwinner,sun6i-a31-spi", },
 474         {}
 475 };
 476 MODULE_DEVICE_TABLE(of, sun6i_spi_match);
 477
 478 static const struct dev_pm_ops sun6i_spi_pm_ops = {
 479         .runtime_resume         = sun6i_spi_runtime_resume,
 480         .runtime_suspend        = sun6i_spi_runtime_suspend,
 481 };
 482
 483 static struct platform_driver sun6i_spi_driver = {
 484         .probe  = sun6i_spi_probe,
 485         .remove = sun6i_spi_remove,
 486         .driver = {
 487                 .name           = "sun6i-spi",
 488                 .of_match_table = sun6i_spi_match,
 489                 .pm             = &sun6i_spi_pm_ops,
 490         },
 491 };
 492 module_platform_driver(sun6i_spi_driver);
 493
 494 MODULE_AUTHOR("Pan Nan <pannan@allwinnertech.com>");
 495 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
 496 MODULE_DESCRIPTION("Allwinner A31 SPI controller driver");
 497 MODULE_LICENSE("GPL");