drivers/spi/spi-sun4i.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
  23 #include <linux/spi/spi.h>
  24
  25 #define SUN4I_FIFO_DEPTH                64
  26
  27 #define SUN4I_RXDATA_REG                0x00
  28
  29 #define SUN4I_TXDATA_REG                0x04
  30
  31 #define SUN4I_CTL_REG                   0x08
  32 #define SUN4I_CTL_ENABLE                        BIT(0)
  33 #define SUN4I_CTL_MASTER                        BIT(1)
  34 #define SUN4I_CTL_CPHA                          BIT(2)
  35 #define SUN4I_CTL_CPOL                          BIT(3)
  36 #define SUN4I_CTL_CS_ACTIVE_LOW                 BIT(4)
  37 #define SUN4I_CTL_LMTF                          BIT(6)
  38 #define SUN4I_CTL_TF_RST                        BIT(8)
  39 #define SUN4I_CTL_RF_RST                        BIT(9)
  40 #define SUN4I_CTL_XCH                           BIT(10)
  41 #define SUN4I_CTL_CS_MASK                       0x3000
  42 #define SUN4I_CTL_CS(cs)                        (((cs) << 12) & SUN4I_CTL_CS_MASK)
  43 #define SUN4I_CTL_DHB                           BIT(15)
  44 #define SUN4I_CTL_CS_MANUAL                     BIT(16)
  45 #define SUN4I_CTL_CS_LEVEL                      BIT(17)
  46 #define SUN4I_CTL_TP                            BIT(18)
  47
  48 #define SUN4I_INT_CTL_REG               0x0c
  49 #define SUN4I_INT_CTL_TC                        BIT(16)
  50
  51 #define SUN4I_INT_STA_REG               0x10
  52
  53 #define SUN4I_DMA_CTL_REG               0x14
  54
  55 #define SUN4I_WAIT_REG                  0x18
  56
  57 #define SUN4I_CLK_CTL_REG               0x1c
  58 #define SUN4I_CLK_CTL_CDR2_MASK                 0xff
  59 #define SUN4I_CLK_CTL_CDR2(div)                 ((div) & SUN4I_CLK_CTL_CDR2_MASK)
  60 #define SUN4I_CLK_CTL_CDR1_MASK                 0xf
  61 #define SUN4I_CLK_CTL_CDR1(div)                 (((div) & SUN4I_CLK_CTL_CDR1_MASK) << 8)
  62 #define SUN4I_CLK_CTL_DRS                       BIT(12)
  63
  64 #define SUN4I_BURST_CNT_REG             0x20
  65 #define SUN4I_BURST_CNT(cnt)                    ((cnt) & 0xffffff)
  66
  67 #define SUN4I_XMIT_CNT_REG              0x24
  68 #define SUN4I_XMIT_CNT(cnt)                     ((cnt) & 0xffffff)
  69
  70 #define SUN4I_FIFO_STA_REG              0x28
  71 #define SUN4I_FIFO_STA_RF_CNT_MASK              0x7f
  72 #define SUN4I_FIFO_STA_RF_CNT_BITS              0
  73 #define SUN4I_FIFO_STA_TF_CNT_MASK              0x7f
  74 #define SUN4I_FIFO_STA_TF_CNT_BITS              16
  75
  76 struct sun4i_spi {
  77         struct spi_master       *master;
  78         void __iomem            *base_addr;
  79         struct clk              *hclk;
  80         struct clk              *mclk;
  81
  82         struct completion       done;
  83
  84         const u8                *tx_buf;
  85         u8                      *rx_buf;
  86         int                     len;
  87 };
  88
  89 static inline u32 sun4i_spi_read(struct sun4i_spi *sspi, u32 reg)
  90 {
  91         return readl(sspi->base_addr + reg);
  92 }
  93
  94 static inline void sun4i_spi_write(struct sun4i_spi *sspi, u32 reg, u32 value)
  95 {
  96         writel(value, sspi->base_addr + reg);
  97 }
  98
  99 static inline void sun4i_spi_drain_fifo(struct sun4i_spi *sspi, int len)
 100 {
 101         u32 reg, cnt;
 102         u8 byte;
 103
 104         /* See how much data is available */
 105         reg = sun4i_spi_read(sspi, SUN4I_FIFO_STA_REG);
 106         reg &= SUN4I_FIFO_STA_RF_CNT_MASK;
 107         cnt = reg >> SUN4I_FIFO_STA_RF_CNT_BITS;
 108
 109         if (len > cnt)
 110                 len = cnt;
 111
 112         while (len--) {
 113                 byte = readb(sspi->base_addr + SUN4I_RXDATA_REG);
 114                 if (sspi->rx_buf)
 115                         *sspi->rx_buf++ = byte;
 116         }
 117 }
 118
 119 static inline void sun4i_spi_fill_fifo(struct sun4i_spi *sspi, int len)
 120 {
 121         u8 byte;
 122
 123         if (len > sspi->len)
 124                 len = sspi->len;
 125
 126         while (len--) {
 127                 byte = sspi->tx_buf ? *sspi->tx_buf++ : 0;
 128                 writeb(byte, sspi->base_addr + SUN4I_TXDATA_REG);
 129                 sspi->len--;
 130         }
 131 }
 132
 133 static void sun4i_spi_set_cs(struct spi_device *spi, bool enable)
 134 {
 135         struct sun4i_spi *sspi = spi_master_get_devdata(spi->master);
 136         u32 reg;
 137
 138         reg = sun4i_spi_read(sspi, SUN4I_CTL_REG);
 139
 140         reg &= ~SUN4I_CTL_CS_MASK;
 141         reg |= SUN4I_CTL_CS(spi->chip_select);
 142
 143         if (enable)
 144                 reg |= SUN4I_CTL_CS_LEVEL;
 145         else
 146                 reg &= ~SUN4I_CTL_CS_LEVEL;
 147
 148         /*
 149          * Even though this looks irrelevant since we are supposed to
 150          * be controlling the chip select manually, this bit also
 151          * controls the levels of the chip select for inactive
 152          * devices.
 153          *
 154          * If we don't set it, the chip select level will go low by
 155          * default when the device is idle, which is not really
 156          * expected in the common case where the chip select is active
 157          * low.
 158          */
 159         if (spi->mode & SPI_CS_HIGH)
 160                 reg &= ~SUN4I_CTL_CS_ACTIVE_LOW;
 161         else
 162                 reg |= SUN4I_CTL_CS_ACTIVE_LOW;
 163
 164         sun4i_spi_write(sspi, SUN4I_CTL_REG, reg);
 165 }
 166
 167 static int sun4i_spi_transfer_one(struct spi_master *master,
 168                                   struct spi_device *spi,
 169                                   struct spi_transfer *tfr)
 170 {
 171         struct sun4i_spi *sspi = spi_master_get_devdata(master);
 172         unsigned int mclk_rate, div, timeout;
 173         unsigned int tx_len = 0;
 174         int ret = 0;
 175         u32 reg;
 176
 177         /* We don't support transfer larger than the FIFO */
 178         if (tfr->len > SUN4I_FIFO_DEPTH)
 179                 return -EINVAL;
 180
 181         reinit_completion(&sspi->done);
 182         sspi->tx_buf = tfr->tx_buf;
 183         sspi->rx_buf = tfr->rx_buf;
 184         sspi->len = tfr->len;
 185
 186         /* Clear pending interrupts */
 187         sun4i_spi_write(sspi, SUN4I_INT_STA_REG, ~0);
 188
 189
 190         reg = sun4i_spi_read(sspi, SUN4I_CTL_REG);
 191
 192         /* Reset FIFOs */
 193         sun4i_spi_write(sspi, SUN4I_CTL_REG,
 194                         reg | SUN4I_CTL_RF_RST | SUN4I_CTL_TF_RST);
 195
 196         /*
 197          * Setup the transfer control register: Chip Select,
 198          * polarities, etc.
 199          */
 200         if (spi->mode & SPI_CPOL)
 201                 reg |= SUN4I_CTL_CPOL;
 202         else
 203                 reg &= ~SUN4I_CTL_CPOL;
 204
 205         if (spi->mode & SPI_CPHA)
 206                 reg |= SUN4I_CTL_CPHA;
 207         else
 208                 reg &= ~SUN4I_CTL_CPHA;
 209
 210         if (spi->mode & SPI_LSB_FIRST)
 211                 reg |= SUN4I_CTL_LMTF;
 212         else
 213                 reg &= ~SUN4I_CTL_LMTF;
 214
 215
 216         /*
 217          * If it's a TX only transfer, we don't want to fill the RX
 218          * FIFO with bogus data
 219          */
 220         if (sspi->rx_buf)
 221                 reg &= ~SUN4I_CTL_DHB;
 222         else
 223                 reg |= SUN4I_CTL_DHB;
 224
 225         /* We want to control the chip select manually */
 226         reg |= SUN4I_CTL_CS_MANUAL;
 227
 228         sun4i_spi_write(sspi, SUN4I_CTL_REG, reg);
 229
 230         /* Ensure that we have a parent clock fast enough */
 231         mclk_rate = clk_get_rate(sspi->mclk);
 232         if (mclk_rate < (2 * spi->max_speed_hz)) {
 233                 clk_set_rate(sspi->mclk, 2 * spi->max_speed_hz);
 234                 mclk_rate = clk_get_rate(sspi->mclk);
 235         }
 236
 237         /*
 238          * Setup clock divider.
 239          *
 240          * We have two choices there. Either we can use the clock
 241          * divide rate 1, which is calculated thanks to this formula:
 242          * SPI_CLK = MOD_CLK / (2 ^ (cdr + 1))
 243          * Or we can use CDR2, which is calculated with the formula:
 244          * SPI_CLK = MOD_CLK / (2 * (cdr + 1))
 245          * Wether we use the former or the latter is set through the
 246          * DRS bit.
 247          *
 248          * First try CDR2, and if we can't reach the expected
 249          * frequency, fall back to CDR1.
 250          */
 251         div = mclk_rate / (2 * spi->max_speed_hz);
 252         if (div <= (SUN4I_CLK_CTL_CDR2_MASK + 1)) {
 253                 if (div > 0)
 254                         div--;
 255
 256                 reg = SUN4I_CLK_CTL_CDR2(div) | SUN4I_CLK_CTL_DRS;
 257         } else {
 258                 div = ilog2(mclk_rate) - ilog2(spi->max_speed_hz);
 259                 reg = SUN4I_CLK_CTL_CDR1(div);
 260         }
 261
 262         sun4i_spi_write(sspi, SUN4I_CLK_CTL_REG, reg);
 263
 264         /* Setup the transfer now... */
 265         if (sspi->tx_buf)
 266                 tx_len = tfr->len;
 267
 268         /* Setup the counters */
 269         sun4i_spi_write(sspi, SUN4I_BURST_CNT_REG, SUN4I_BURST_CNT(tfr->len));
 270         sun4i_spi_write(sspi, SUN4I_XMIT_CNT_REG, SUN4I_XMIT_CNT(tx_len));
 271
 272         /* Fill the TX FIFO */
 273         sun4i_spi_fill_fifo(sspi, SUN4I_FIFO_DEPTH);
 274
 275         /* Enable the interrupts */
 276         sun4i_spi_write(sspi, SUN4I_INT_CTL_REG, SUN4I_INT_CTL_TC);
 277
 278         /* Start the transfer */
 279         reg = sun4i_spi_read(sspi, SUN4I_CTL_REG);
 280         sun4i_spi_write(sspi, SUN4I_CTL_REG, reg | SUN4I_CTL_XCH);
 281
 282         timeout = wait_for_completion_timeout(&sspi->done,
 283                                               msecs_to_jiffies(1000));
 284         if (!timeout) {
 285                 ret = -ETIMEDOUT;
 286                 goto out;
 287         }
 288
 289         sun4i_spi_drain_fifo(sspi, SUN4I_FIFO_DEPTH);
 290
 291 out:
 292         sun4i_spi_write(sspi, SUN4I_INT_CTL_REG, 0);
 293
 294         return ret;
 295 }
 296
 297 static irqreturn_t sun4i_spi_handler(int irq, void *dev_id)
 298 {
 299         struct sun4i_spi *sspi = dev_id;
 300         u32 status = sun4i_spi_read(sspi, SUN4I_INT_STA_REG);
 301
 302         /* Transfer complete */
 303         if (status & SUN4I_INT_CTL_TC) {
 304                 sun4i_spi_write(sspi, SUN4I_INT_STA_REG, SUN4I_INT_CTL_TC);
 305                 complete(&sspi->done);
 306                 return IRQ_HANDLED;
 307         }
 308
 309         return IRQ_NONE;
 310 }
 311
 312 static int sun4i_spi_runtime_resume(struct device *dev)
 313 {
 314         struct spi_master *master = dev_get_drvdata(dev);
 315         struct sun4i_spi *sspi = spi_master_get_devdata(master);
 316         int ret;
 317
 318         ret = clk_prepare_enable(sspi->hclk);
 319         if (ret) {
 320                 dev_err(dev, "Couldn't enable AHB clock\n");
 321                 goto out;
 322         }
 323
 324         ret = clk_prepare_enable(sspi->mclk);
 325         if (ret) {
 326                 dev_err(dev, "Couldn't enable module clock\n");
 327                 goto err;
 328         }
 329
 330         sun4i_spi_write(sspi, SUN4I_CTL_REG,
 331                         SUN4I_CTL_ENABLE | SUN4I_CTL_MASTER | SUN4I_CTL_TP);
 332
 333         return 0;
 334
 335 err:
 336         clk_disable_unprepare(sspi->hclk);
 337 out:
 338         return ret;
 339 }
 340
 341 static int sun4i_spi_runtime_suspend(struct device *dev)
 342 {
 343         struct spi_master *master = dev_get_drvdata(dev);
 344         struct sun4i_spi *sspi = spi_master_get_devdata(master);
 345
 346         clk_disable_unprepare(sspi->mclk);
 347         clk_disable_unprepare(sspi->hclk);
 348
 349         return 0;
 350 }
 351
 352 static int sun4i_spi_probe(struct platform_device *pdev)
 353 {
 354         struct spi_master *master;
 355         struct sun4i_spi *sspi;
 356         struct resource *res;
 357         int ret = 0, irq;
 358
 359         master = spi_alloc_master(&pdev->dev, sizeof(struct sun4i_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, sun4i_spi_handler,
 383                                0, "sun4i-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 = sun4i_spi_set_cs;
 391         master->transfer_one = sun4i_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         /*
 415          * This wake-up/shutdown pattern is to be able to have the
 416          * device woken up, even if runtime_pm is disabled
 417          */
 418         ret = sun4i_spi_runtime_resume(&pdev->dev);
 419         if (ret) {
 420                 dev_err(&pdev->dev, "Couldn't resume the device\n");
 421                 goto err_free_master;
 422         }
 423
 424         pm_runtime_set_active(&pdev->dev);
 425         pm_runtime_enable(&pdev->dev);
 426         pm_runtime_idle(&pdev->dev);
 427
 428         ret = devm_spi_register_master(&pdev->dev, master);
 429         if (ret) {
 430                 dev_err(&pdev->dev, "cannot register SPI master\n");
 431                 goto err_pm_disable;
 432         }
 433
 434         return 0;
 435
 436 err_pm_disable:
 437         pm_runtime_disable(&pdev->dev);
 438         sun4i_spi_runtime_suspend(&pdev->dev);
 439 err_free_master:
 440         spi_master_put(master);
 441         return ret;
 442 }
 443
 444 static int sun4i_spi_remove(struct platform_device *pdev)
 445 {
 446         pm_runtime_disable(&pdev->dev);
 447
 448         return 0;
 449 }
 450
 451 static const struct of_device_id sun4i_spi_match[] = {
 452         { .compatible = "allwinner,sun4i-a10-spi", },
 453         {}
 454 };
 455 MODULE_DEVICE_TABLE(of, sun4i_spi_match);
 456
 457 static const struct dev_pm_ops sun4i_spi_pm_ops = {
 458         .runtime_resume         = sun4i_spi_runtime_resume,
 459         .runtime_suspend        = sun4i_spi_runtime_suspend,
 460 };
 461
 462 static struct platform_driver sun4i_spi_driver = {
 463         .probe  = sun4i_spi_probe,
 464         .remove = sun4i_spi_remove,
 465         .driver = {
 466                 .name           = "sun4i-spi",
 467                 .of_match_table = sun4i_spi_match,
 468                 .pm             = &sun4i_spi_pm_ops,
 469         },
 470 };
 471 module_platform_driver(sun4i_spi_driver);
 472
 473 MODULE_AUTHOR("Pan Nan <pannan@allwinnertech.com>");
 474 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
 475 MODULE_DESCRIPTION("Allwinner A1X/A20 SPI controller driver");
 476 MODULE_LICENSE("GPL");