root/drivers/spi/spi-sun4i.c

DEFINITIONS

1. sun4i_spi_read
2. sun4i_spi_write
3. sun4i_spi_get_tx_fifo_count
4. sun4i_spi_enable_interrupt
5. sun4i_spi_disable_interrupt
6. sun4i_spi_drain_fifo
7. sun4i_spi_fill_fifo
8. sun4i_spi_set_cs
9. sun4i_spi_max_transfer_size
10. sun4i_spi_transfer_one
11. sun4i_spi_handler
12. sun4i_spi_runtime_resume
13. sun4i_spi_runtime_suspend
14. sun4i_spi_probe
15. sun4i_spi_remove

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (C) 2012 - 2014 Allwinner Tech
   4  * Pan Nan <pannan@allwinnertech.com>
   5  *
   6  * Copyright (C) 2014 Maxime Ripard
   7  * Maxime Ripard <maxime.ripard@free-electrons.com>
   8  */
   9 
  10 #include <linux/clk.h>
  11 #include <linux/delay.h>
  12 #include <linux/device.h>
  13 #include <linux/interrupt.h>
  14 #include <linux/io.h>
  15 #include <linux/module.h>
  16 #include <linux/platform_device.h>
  17 #include <linux/pm_runtime.h>
  18 
  19 #include <linux/spi/spi.h>
  20 
  21 #define SUN4I_FIFO_DEPTH                64
  22 
  23 #define SUN4I_RXDATA_REG                0x00
  24 
  25 #define SUN4I_TXDATA_REG                0x04
  26 
  27 #define SUN4I_CTL_REG                   0x08
  28 #define SUN4I_CTL_ENABLE                        BIT(0)
  29 #define SUN4I_CTL_MASTER                        BIT(1)
  30 #define SUN4I_CTL_CPHA                          BIT(2)
  31 #define SUN4I_CTL_CPOL                          BIT(3)
  32 #define SUN4I_CTL_CS_ACTIVE_LOW                 BIT(4)
  33 #define SUN4I_CTL_LMTF                          BIT(6)
  34 #define SUN4I_CTL_TF_RST                        BIT(8)
  35 #define SUN4I_CTL_RF_RST                        BIT(9)
  36 #define SUN4I_CTL_XCH                           BIT(10)
  37 #define SUN4I_CTL_CS_MASK                       0x3000
  38 #define SUN4I_CTL_CS(cs)                        (((cs) << 12) & SUN4I_CTL_CS_MASK)
  39 #define SUN4I_CTL_DHB                           BIT(15)
  40 #define SUN4I_CTL_CS_MANUAL                     BIT(16)
  41 #define SUN4I_CTL_CS_LEVEL                      BIT(17)
  42 #define SUN4I_CTL_TP                            BIT(18)
  43 
  44 #define SUN4I_INT_CTL_REG               0x0c
  45 #define SUN4I_INT_CTL_RF_F34                    BIT(4)
  46 #define SUN4I_INT_CTL_TF_E34                    BIT(12)
  47 #define SUN4I_INT_CTL_TC                        BIT(16)
  48 
  49 #define SUN4I_INT_STA_REG               0x10
  50 
  51 #define SUN4I_DMA_CTL_REG               0x14
  52 
  53 #define SUN4I_WAIT_REG                  0x18
  54 
  55 #define SUN4I_CLK_CTL_REG               0x1c
  56 #define SUN4I_CLK_CTL_CDR2_MASK                 0xff
  57 #define SUN4I_CLK_CTL_CDR2(div)                 ((div) & SUN4I_CLK_CTL_CDR2_MASK)
  58 #define SUN4I_CLK_CTL_CDR1_MASK                 0xf
  59 #define SUN4I_CLK_CTL_CDR1(div)                 (((div) & SUN4I_CLK_CTL_CDR1_MASK) << 8)
  60 #define SUN4I_CLK_CTL_DRS                       BIT(12)
  61 
  62 #define SUN4I_MAX_XFER_SIZE                     0xffffff
  63 
  64 #define SUN4I_BURST_CNT_REG             0x20
  65 #define SUN4I_BURST_CNT(cnt)                    ((cnt) & SUN4I_MAX_XFER_SIZE)
  66 
  67 #define SUN4I_XMIT_CNT_REG              0x24
  68 #define SUN4I_XMIT_CNT(cnt)                     ((cnt) & SUN4I_MAX_XFER_SIZE)
  69 
  70 
  71 #define SUN4I_FIFO_STA_REG              0x28
  72 #define SUN4I_FIFO_STA_RF_CNT_MASK              0x7f
  73 #define SUN4I_FIFO_STA_RF_CNT_BITS              0
  74 #define SUN4I_FIFO_STA_TF_CNT_MASK              0x7f
  75 #define SUN4I_FIFO_STA_TF_CNT_BITS              16
  76 
  77 struct sun4i_spi {
  78         struct spi_master       *master;
  79         void __iomem            *base_addr;
  80         struct clk              *hclk;
  81         struct clk              *mclk;
  82 
  83         struct completion       done;
  84 
  85         const u8                *tx_buf;
  86         u8                      *rx_buf;
  87         int                     len;
  88 };
  89 
  90 static inline u32 sun4i_spi_read(struct sun4i_spi *sspi, u32 reg)
  91 {
  92         return readl(sspi->base_addr + reg);
  93 }
  94 
  95 static inline void sun4i_spi_write(struct sun4i_spi *sspi, u32 reg, u32 value)
  96 {
  97         writel(value, sspi->base_addr + reg);
  98 }
  99 
 100 static inline u32 sun4i_spi_get_tx_fifo_count(struct sun4i_spi *sspi)
 101 {
 102         u32 reg = sun4i_spi_read(sspi, SUN4I_FIFO_STA_REG);
 103 
 104         reg >>= SUN4I_FIFO_STA_TF_CNT_BITS;
 105 
 106         return reg & SUN4I_FIFO_STA_TF_CNT_MASK;
 107 }
 108 
 109 static inline void sun4i_spi_enable_interrupt(struct sun4i_spi *sspi, u32 mask)
 110 {
 111         u32 reg = sun4i_spi_read(sspi, SUN4I_INT_CTL_REG);
 112 
 113         reg |= mask;
 114         sun4i_spi_write(sspi, SUN4I_INT_CTL_REG, reg);
 115 }
 116 
 117 static inline void sun4i_spi_disable_interrupt(struct sun4i_spi *sspi, u32 mask)
 118 {
 119         u32 reg = sun4i_spi_read(sspi, SUN4I_INT_CTL_REG);
 120 
 121         reg &= ~mask;
 122         sun4i_spi_write(sspi, SUN4I_INT_CTL_REG, reg);
 123 }
 124 
 125 static inline void sun4i_spi_drain_fifo(struct sun4i_spi *sspi, int len)
 126 {
 127         u32 reg, cnt;
 128         u8 byte;
 129 
 130         /* See how much data is available */
 131         reg = sun4i_spi_read(sspi, SUN4I_FIFO_STA_REG);
 132         reg &= SUN4I_FIFO_STA_RF_CNT_MASK;
 133         cnt = reg >> SUN4I_FIFO_STA_RF_CNT_BITS;
 134 
 135         if (len > cnt)
 136                 len = cnt;
 137 
 138         while (len--) {
 139                 byte = readb(sspi->base_addr + SUN4I_RXDATA_REG);
 140                 if (sspi->rx_buf)
 141                         *sspi->rx_buf++ = byte;
 142         }
 143 }
 144 
 145 static inline void sun4i_spi_fill_fifo(struct sun4i_spi *sspi, int len)
 146 {
 147         u32 cnt;
 148         u8 byte;
 149 
 150         /* See how much data we can fit */
 151         cnt = SUN4I_FIFO_DEPTH - sun4i_spi_get_tx_fifo_count(sspi);
 152 
 153         len = min3(len, (int)cnt, sspi->len);
 154 
 155         while (len--) {
 156                 byte = sspi->tx_buf ? *sspi->tx_buf++ : 0;
 157                 writeb(byte, sspi->base_addr + SUN4I_TXDATA_REG);
 158                 sspi->len--;
 159         }
 160 }
 161 
 162 static void sun4i_spi_set_cs(struct spi_device *spi, bool enable)
 163 {
 164         struct sun4i_spi *sspi = spi_master_get_devdata(spi->master);
 165         u32 reg;
 166 
 167         reg = sun4i_spi_read(sspi, SUN4I_CTL_REG);
 168 
 169         reg &= ~SUN4I_CTL_CS_MASK;
 170         reg |= SUN4I_CTL_CS(spi->chip_select);
 171 
 172         /* We want to control the chip select manually */
 173         reg |= SUN4I_CTL_CS_MANUAL;
 174 
 175         if (enable)
 176                 reg |= SUN4I_CTL_CS_LEVEL;
 177         else
 178                 reg &= ~SUN4I_CTL_CS_LEVEL;
 179 
 180         /*
 181          * Even though this looks irrelevant since we are supposed to
 182          * be controlling the chip select manually, this bit also
 183          * controls the levels of the chip select for inactive
 184          * devices.
 185          *
 186          * If we don't set it, the chip select level will go low by
 187          * default when the device is idle, which is not really
 188          * expected in the common case where the chip select is active
 189          * low.
 190          */
 191         if (spi->mode & SPI_CS_HIGH)
 192                 reg &= ~SUN4I_CTL_CS_ACTIVE_LOW;
 193         else
 194                 reg |= SUN4I_CTL_CS_ACTIVE_LOW;
 195 
 196         sun4i_spi_write(sspi, SUN4I_CTL_REG, reg);
 197 }
 198 
 199 static size_t sun4i_spi_max_transfer_size(struct spi_device *spi)
 200 {
 201         return SUN4I_FIFO_DEPTH - 1;
 202 }
 203 
 204 static int sun4i_spi_transfer_one(struct spi_master *master,
 205                                   struct spi_device *spi,
 206                                   struct spi_transfer *tfr)
 207 {
 208         struct sun4i_spi *sspi = spi_master_get_devdata(master);
 209         unsigned int mclk_rate, div, timeout;
 210         unsigned int start, end, tx_time;
 211         unsigned int tx_len = 0;
 212         int ret = 0;
 213         u32 reg;
 214 
 215         /* We don't support transfer larger than the FIFO */
 216         if (tfr->len > SUN4I_MAX_XFER_SIZE)
 217                 return -EMSGSIZE;
 218 
 219         if (tfr->tx_buf && tfr->len >= SUN4I_MAX_XFER_SIZE)
 220                 return -EMSGSIZE;
 221 
 222         reinit_completion(&sspi->done);
 223         sspi->tx_buf = tfr->tx_buf;
 224         sspi->rx_buf = tfr->rx_buf;
 225         sspi->len = tfr->len;
 226 
 227         /* Clear pending interrupts */
 228         sun4i_spi_write(sspi, SUN4I_INT_STA_REG, ~0);
 229 
 230 
 231         reg = sun4i_spi_read(sspi, SUN4I_CTL_REG);
 232 
 233         /* Reset FIFOs */
 234         sun4i_spi_write(sspi, SUN4I_CTL_REG,
 235                         reg | SUN4I_CTL_RF_RST | SUN4I_CTL_TF_RST);
 236 
 237         /*
 238          * Setup the transfer control register: Chip Select,
 239          * polarities, etc.
 240          */
 241         if (spi->mode & SPI_CPOL)
 242                 reg |= SUN4I_CTL_CPOL;
 243         else
 244                 reg &= ~SUN4I_CTL_CPOL;
 245 
 246         if (spi->mode & SPI_CPHA)
 247                 reg |= SUN4I_CTL_CPHA;
 248         else
 249                 reg &= ~SUN4I_CTL_CPHA;
 250 
 251         if (spi->mode & SPI_LSB_FIRST)
 252                 reg |= SUN4I_CTL_LMTF;
 253         else
 254                 reg &= ~SUN4I_CTL_LMTF;
 255 
 256 
 257         /*
 258          * If it's a TX only transfer, we don't want to fill the RX
 259          * FIFO with bogus data
 260          */
 261         if (sspi->rx_buf)
 262                 reg &= ~SUN4I_CTL_DHB;
 263         else
 264                 reg |= SUN4I_CTL_DHB;
 265 
 266         sun4i_spi_write(sspi, SUN4I_CTL_REG, reg);
 267 
 268         /* Ensure that we have a parent clock fast enough */
 269         mclk_rate = clk_get_rate(sspi->mclk);
 270         if (mclk_rate < (2 * tfr->speed_hz)) {
 271                 clk_set_rate(sspi->mclk, 2 * tfr->speed_hz);
 272                 mclk_rate = clk_get_rate(sspi->mclk);
 273         }
 274 
 275         /*
 276          * Setup clock divider.
 277          *
 278          * We have two choices there. Either we can use the clock
 279          * divide rate 1, which is calculated thanks to this formula:
 280          * SPI_CLK = MOD_CLK / (2 ^ (cdr + 1))
 281          * Or we can use CDR2, which is calculated with the formula:
 282          * SPI_CLK = MOD_CLK / (2 * (cdr + 1))
 283          * Wether we use the former or the latter is set through the
 284          * DRS bit.
 285          *
 286          * First try CDR2, and if we can't reach the expected
 287          * frequency, fall back to CDR1.
 288          */
 289         div = mclk_rate / (2 * tfr->speed_hz);
 290         if (div <= (SUN4I_CLK_CTL_CDR2_MASK + 1)) {
 291                 if (div > 0)
 292                         div--;
 293 
 294                 reg = SUN4I_CLK_CTL_CDR2(div) | SUN4I_CLK_CTL_DRS;
 295         } else {
 296                 div = ilog2(mclk_rate) - ilog2(tfr->speed_hz);
 297                 reg = SUN4I_CLK_CTL_CDR1(div);
 298         }
 299 
 300         sun4i_spi_write(sspi, SUN4I_CLK_CTL_REG, reg);
 301 
 302         /* Setup the transfer now... */
 303         if (sspi->tx_buf)
 304                 tx_len = tfr->len;
 305 
 306         /* Setup the counters */
 307         sun4i_spi_write(sspi, SUN4I_BURST_CNT_REG, SUN4I_BURST_CNT(tfr->len));
 308         sun4i_spi_write(sspi, SUN4I_XMIT_CNT_REG, SUN4I_XMIT_CNT(tx_len));
 309 
 310         /*
 311          * Fill the TX FIFO
 312          * Filling the FIFO fully causes timeout for some reason
 313          * at least on spi2 on A10s
 314          */
 315         sun4i_spi_fill_fifo(sspi, SUN4I_FIFO_DEPTH - 1);
 316 
 317         /* Enable the interrupts */
 318         sun4i_spi_enable_interrupt(sspi, SUN4I_INT_CTL_TC |
 319                                          SUN4I_INT_CTL_RF_F34);
 320         /* Only enable Tx FIFO interrupt if we really need it */
 321         if (tx_len > SUN4I_FIFO_DEPTH)
 322                 sun4i_spi_enable_interrupt(sspi, SUN4I_INT_CTL_TF_E34);
 323 
 324         /* Start the transfer */
 325         reg = sun4i_spi_read(sspi, SUN4I_CTL_REG);
 326         sun4i_spi_write(sspi, SUN4I_CTL_REG, reg | SUN4I_CTL_XCH);
 327 
 328         tx_time = max(tfr->len * 8 * 2 / (tfr->speed_hz / 1000), 100U);
 329         start = jiffies;
 330         timeout = wait_for_completion_timeout(&sspi->done,
 331                                               msecs_to_jiffies(tx_time));
 332         end = jiffies;
 333         if (!timeout) {
 334                 dev_warn(&master->dev,
 335                          "%s: timeout transferring %u bytes@%iHz for %i(%i)ms",
 336                          dev_name(&spi->dev), tfr->len, tfr->speed_hz,
 337                          jiffies_to_msecs(end - start), tx_time);
 338                 ret = -ETIMEDOUT;
 339                 goto out;
 340         }
 341 
 342 
 343 out:
 344         sun4i_spi_write(sspi, SUN4I_INT_CTL_REG, 0);
 345 
 346         return ret;
 347 }
 348 
 349 static irqreturn_t sun4i_spi_handler(int irq, void *dev_id)
 350 {
 351         struct sun4i_spi *sspi = dev_id;
 352         u32 status = sun4i_spi_read(sspi, SUN4I_INT_STA_REG);
 353 
 354         /* Transfer complete */
 355         if (status & SUN4I_INT_CTL_TC) {
 356                 sun4i_spi_write(sspi, SUN4I_INT_STA_REG, SUN4I_INT_CTL_TC);
 357                 sun4i_spi_drain_fifo(sspi, SUN4I_FIFO_DEPTH);
 358                 complete(&sspi->done);
 359                 return IRQ_HANDLED;
 360         }
 361 
 362         /* Receive FIFO 3/4 full */
 363         if (status & SUN4I_INT_CTL_RF_F34) {
 364                 sun4i_spi_drain_fifo(sspi, SUN4I_FIFO_DEPTH);
 365                 /* Only clear the interrupt _after_ draining the FIFO */
 366                 sun4i_spi_write(sspi, SUN4I_INT_STA_REG, SUN4I_INT_CTL_RF_F34);
 367                 return IRQ_HANDLED;
 368         }
 369 
 370         /* Transmit FIFO 3/4 empty */
 371         if (status & SUN4I_INT_CTL_TF_E34) {
 372                 sun4i_spi_fill_fifo(sspi, SUN4I_FIFO_DEPTH);
 373 
 374                 if (!sspi->len)
 375                         /* nothing left to transmit */
 376                         sun4i_spi_disable_interrupt(sspi, SUN4I_INT_CTL_TF_E34);
 377 
 378                 /* Only clear the interrupt _after_ re-seeding the FIFO */
 379                 sun4i_spi_write(sspi, SUN4I_INT_STA_REG, SUN4I_INT_CTL_TF_E34);
 380 
 381                 return IRQ_HANDLED;
 382         }
 383 
 384         return IRQ_NONE;
 385 }
 386 
 387 static int sun4i_spi_runtime_resume(struct device *dev)
 388 {
 389         struct spi_master *master = dev_get_drvdata(dev);
 390         struct sun4i_spi *sspi = spi_master_get_devdata(master);
 391         int ret;
 392 
 393         ret = clk_prepare_enable(sspi->hclk);
 394         if (ret) {
 395                 dev_err(dev, "Couldn't enable AHB clock\n");
 396                 goto out;
 397         }
 398 
 399         ret = clk_prepare_enable(sspi->mclk);
 400         if (ret) {
 401                 dev_err(dev, "Couldn't enable module clock\n");
 402                 goto err;
 403         }
 404 
 405         sun4i_spi_write(sspi, SUN4I_CTL_REG,
 406                         SUN4I_CTL_ENABLE | SUN4I_CTL_MASTER | SUN4I_CTL_TP);
 407 
 408         return 0;
 409 
 410 err:
 411         clk_disable_unprepare(sspi->hclk);
 412 out:
 413         return ret;
 414 }
 415 
 416 static int sun4i_spi_runtime_suspend(struct device *dev)
 417 {
 418         struct spi_master *master = dev_get_drvdata(dev);
 419         struct sun4i_spi *sspi = spi_master_get_devdata(master);
 420 
 421         clk_disable_unprepare(sspi->mclk);
 422         clk_disable_unprepare(sspi->hclk);
 423 
 424         return 0;
 425 }
 426 
 427 static int sun4i_spi_probe(struct platform_device *pdev)
 428 {
 429         struct spi_master *master;
 430         struct sun4i_spi *sspi;
 431         int ret = 0, irq;
 432 
 433         master = spi_alloc_master(&pdev->dev, sizeof(struct sun4i_spi));
 434         if (!master) {
 435                 dev_err(&pdev->dev, "Unable to allocate SPI Master\n");
 436                 return -ENOMEM;
 437         }
 438 
 439         platform_set_drvdata(pdev, master);
 440         sspi = spi_master_get_devdata(master);
 441 
 442         sspi->base_addr = devm_platform_ioremap_resource(pdev, 0);
 443         if (IS_ERR(sspi->base_addr)) {
 444                 ret = PTR_ERR(sspi->base_addr);
 445                 goto err_free_master;
 446         }
 447 
 448         irq = platform_get_irq(pdev, 0);
 449         if (irq < 0) {
 450                 ret = -ENXIO;
 451                 goto err_free_master;
 452         }
 453 
 454         ret = devm_request_irq(&pdev->dev, irq, sun4i_spi_handler,
 455                                0, "sun4i-spi", sspi);
 456         if (ret) {
 457                 dev_err(&pdev->dev, "Cannot request IRQ\n");
 458                 goto err_free_master;
 459         }
 460 
 461         sspi->master = master;
 462         master->max_speed_hz = 100 * 1000 * 1000;
 463         master->min_speed_hz = 3 * 1000;
 464         master->set_cs = sun4i_spi_set_cs;
 465         master->transfer_one = sun4i_spi_transfer_one;
 466         master->num_chipselect = 4;
 467         master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH | SPI_LSB_FIRST;
 468         master->bits_per_word_mask = SPI_BPW_MASK(8);
 469         master->dev.of_node = pdev->dev.of_node;
 470         master->auto_runtime_pm = true;
 471         master->max_transfer_size = sun4i_spi_max_transfer_size;
 472 
 473         sspi->hclk = devm_clk_get(&pdev->dev, "ahb");
 474         if (IS_ERR(sspi->hclk)) {
 475                 dev_err(&pdev->dev, "Unable to acquire AHB clock\n");
 476                 ret = PTR_ERR(sspi->hclk);
 477                 goto err_free_master;
 478         }
 479 
 480         sspi->mclk = devm_clk_get(&pdev->dev, "mod");
 481         if (IS_ERR(sspi->mclk)) {
 482                 dev_err(&pdev->dev, "Unable to acquire module clock\n");
 483                 ret = PTR_ERR(sspi->mclk);
 484                 goto err_free_master;
 485         }
 486 
 487         init_completion(&sspi->done);
 488 
 489         /*
 490          * This wake-up/shutdown pattern is to be able to have the
 491          * device woken up, even if runtime_pm is disabled
 492          */
 493         ret = sun4i_spi_runtime_resume(&pdev->dev);
 494         if (ret) {
 495                 dev_err(&pdev->dev, "Couldn't resume the device\n");
 496                 goto err_free_master;
 497         }
 498 
 499         pm_runtime_set_active(&pdev->dev);
 500         pm_runtime_enable(&pdev->dev);
 501         pm_runtime_idle(&pdev->dev);
 502 
 503         ret = devm_spi_register_master(&pdev->dev, master);
 504         if (ret) {
 505                 dev_err(&pdev->dev, "cannot register SPI master\n");
 506                 goto err_pm_disable;
 507         }
 508 
 509         return 0;
 510 
 511 err_pm_disable:
 512         pm_runtime_disable(&pdev->dev);
 513         sun4i_spi_runtime_suspend(&pdev->dev);
 514 err_free_master:
 515         spi_master_put(master);
 516         return ret;
 517 }
 518 
 519 static int sun4i_spi_remove(struct platform_device *pdev)
 520 {
 521         pm_runtime_force_suspend(&pdev->dev);
 522 
 523         return 0;
 524 }
 525 
 526 static const struct of_device_id sun4i_spi_match[] = {
 527         { .compatible = "allwinner,sun4i-a10-spi", },
 528         {}
 529 };
 530 MODULE_DEVICE_TABLE(of, sun4i_spi_match);
 531 
 532 static const struct dev_pm_ops sun4i_spi_pm_ops = {
 533         .runtime_resume         = sun4i_spi_runtime_resume,
 534         .runtime_suspend        = sun4i_spi_runtime_suspend,
 535 };
 536 
 537 static struct platform_driver sun4i_spi_driver = {
 538         .probe  = sun4i_spi_probe,
 539         .remove = sun4i_spi_remove,
 540         .driver = {
 541                 .name           = "sun4i-spi",
 542                 .of_match_table = sun4i_spi_match,
 543                 .pm             = &sun4i_spi_pm_ops,
 544         },
 545 };
 546 module_platform_driver(sun4i_spi_driver);
 547 
 548 MODULE_AUTHOR("Pan Nan <pannan@allwinnertech.com>");
 549 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
 550 MODULE_DESCRIPTION("Allwinner A1X/A20 SPI controller driver");
 551 MODULE_LICENSE("GPL");