drivers/spi/spi-fsl-lpspi.c

   1 /*
   2  * Freescale i.MX7ULP LPSPI driver
   3  *
   4  * Copyright 2016 Freescale Semiconductor, Inc.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  */
  17
  18 #include <linux/clk.h>
  19 #include <linux/completion.h>
  20 #include <linux/delay.h>
  21 #include <linux/err.h>
  22 #include <linux/interrupt.h>
  23 #include <linux/io.h>
  24 #include <linux/irq.h>
  25 #include <linux/kernel.h>
  26 #include <linux/module.h>
  27 #include <linux/of.h>
  28 #include <linux/of_device.h>
  29 #include <linux/platform_device.h>
  30 #include <linux/slab.h>
  31 #include <linux/spi/spi.h>
  32 #include <linux/spi/spi_bitbang.h>
  33 #include <linux/types.h>
  34
  35 #define DRIVER_NAME "fsl_lpspi"
  36
  37 /* i.MX7ULP LPSPI registers */
  38 #define IMX7ULP_VERID   0x0
  39 #define IMX7ULP_PARAM   0x4
  40 #define IMX7ULP_CR      0x10
  41 #define IMX7ULP_SR      0x14
  42 #define IMX7ULP_IER     0x18
  43 #define IMX7ULP_DER     0x1c
  44 #define IMX7ULP_CFGR0   0x20
  45 #define IMX7ULP_CFGR1   0x24
  46 #define IMX7ULP_DMR0    0x30
  47 #define IMX7ULP_DMR1    0x34
  48 #define IMX7ULP_CCR     0x40
  49 #define IMX7ULP_FCR     0x58
  50 #define IMX7ULP_FSR     0x5c
  51 #define IMX7ULP_TCR     0x60
  52 #define IMX7ULP_TDR     0x64
  53 #define IMX7ULP_RSR     0x70
  54 #define IMX7ULP_RDR     0x74
  55
  56 /* General control register field define */
  57 #define CR_RRF          BIT(9)
  58 #define CR_RTF          BIT(8)
  59 #define CR_RST          BIT(1)
  60 #define CR_MEN          BIT(0)
  61 #define SR_TCF          BIT(10)
  62 #define SR_RDF          BIT(1)
  63 #define SR_TDF          BIT(0)
  64 #define IER_TCIE        BIT(10)
  65 #define IER_RDIE        BIT(1)
  66 #define IER_TDIE        BIT(0)
  67 #define CFGR1_PCSCFG    BIT(27)
  68 #define CFGR1_PCSPOL    BIT(8)
  69 #define CFGR1_NOSTALL   BIT(3)
  70 #define CFGR1_MASTER    BIT(0)
  71 #define RSR_RXEMPTY     BIT(1)
  72 #define TCR_CPOL        BIT(31)
  73 #define TCR_CPHA        BIT(30)
  74 #define TCR_CONT        BIT(21)
  75 #define TCR_CONTC       BIT(20)
  76 #define TCR_RXMSK       BIT(19)
  77 #define TCR_TXMSK       BIT(18)
  78
  79 static int clkdivs[] = {1, 2, 4, 8, 16, 32, 64, 128};
  80
  81 struct lpspi_config {
  82         u8 bpw;
  83         u8 chip_select;
  84         u8 prescale;
  85         u16 mode;
  86         u32 speed_hz;
  87 };
  88
  89 struct fsl_lpspi_data {
  90         struct device *dev;
  91         void __iomem *base;
  92         struct clk *clk;
  93
  94         void *rx_buf;
  95         const void *tx_buf;
  96         void (*tx)(struct fsl_lpspi_data *);
  97         void (*rx)(struct fsl_lpspi_data *);
  98
  99         u32 remain;
 100         u8 txfifosize;
 101         u8 rxfifosize;
 102
 103         struct lpspi_config config;
 104         struct completion xfer_done;
 105 };
 106
 107 static const struct of_device_id fsl_lpspi_dt_ids[] = {
 108         { .compatible = "fsl,imx7ulp-spi", },
 109         { /* sentinel */ }
 110 };
 111 MODULE_DEVICE_TABLE(of, fsl_lpspi_dt_ids);
 112
 113 #define LPSPI_BUF_RX(type)                                              \
 114 static void fsl_lpspi_buf_rx_##type(struct fsl_lpspi_data *fsl_lpspi)   \
 115 {                                                                       \
 116         unsigned int val = readl(fsl_lpspi->base + IMX7ULP_RDR);        \
 117                                                                         \
 118         if (fsl_lpspi->rx_buf) {                                        \
 119                 *(type *)fsl_lpspi->rx_buf = val;                       \
 120                 fsl_lpspi->rx_buf += sizeof(type);                      \
 121         }                                                               \
 122 }
 123
 124 #define LPSPI_BUF_TX(type)                                              \
 125 static void fsl_lpspi_buf_tx_##type(struct fsl_lpspi_data *fsl_lpspi)   \
 126 {                                                                       \
 127         type val = 0;                                                   \
 128                                                                         \
 129         if (fsl_lpspi->tx_buf) {                                        \
 130                 val = *(type *)fsl_lpspi->tx_buf;                       \
 131                 fsl_lpspi->tx_buf += sizeof(type);                      \
 132         }                                                               \
 133                                                                         \
 134         fsl_lpspi->remain -= sizeof(type);                              \
 135         writel(val, fsl_lpspi->base + IMX7ULP_TDR);                     \
 136 }
 137
 138 LPSPI_BUF_RX(u8)
 139 LPSPI_BUF_TX(u8)
 140 LPSPI_BUF_RX(u16)
 141 LPSPI_BUF_TX(u16)
 142 LPSPI_BUF_RX(u32)
 143 LPSPI_BUF_TX(u32)
 144
 145 static void fsl_lpspi_intctrl(struct fsl_lpspi_data *fsl_lpspi,
 146                               unsigned int enable)
 147 {
 148         writel(enable, fsl_lpspi->base + IMX7ULP_IER);
 149 }
 150
 151 static int lpspi_prepare_xfer_hardware(struct spi_master *master)
 152 {
 153         struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(master);
 154
 155         return clk_prepare_enable(fsl_lpspi->clk);
 156 }
 157
 158 static int lpspi_unprepare_xfer_hardware(struct spi_master *master)
 159 {
 160         struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(master);
 161
 162         clk_disable_unprepare(fsl_lpspi->clk);
 163
 164         return 0;
 165 }
 166
 167 static int fsl_lpspi_txfifo_empty(struct fsl_lpspi_data *fsl_lpspi)
 168 {
 169         u32 txcnt;
 170         unsigned long orig_jiffies = jiffies;
 171
 172         do {
 173                 txcnt = readl(fsl_lpspi->base + IMX7ULP_FSR) & 0xff;
 174
 175                 if (time_after(jiffies, orig_jiffies + msecs_to_jiffies(500))) {
 176                         dev_dbg(fsl_lpspi->dev, "txfifo empty timeout\n");
 177                         return -ETIMEDOUT;
 178                 }
 179                 cond_resched();
 180
 181         } while (txcnt);
 182
 183         return 0;
 184 }
 185
 186 static void fsl_lpspi_write_tx_fifo(struct fsl_lpspi_data *fsl_lpspi)
 187 {
 188         u8 txfifo_cnt;
 189
 190         txfifo_cnt = readl(fsl_lpspi->base + IMX7ULP_FSR) & 0xff;
 191
 192         while (txfifo_cnt < fsl_lpspi->txfifosize) {
 193                 if (!fsl_lpspi->remain)
 194                         break;
 195                 fsl_lpspi->tx(fsl_lpspi);
 196                 txfifo_cnt++;
 197         }
 198
 199         if (!fsl_lpspi->remain && (txfifo_cnt < fsl_lpspi->txfifosize))
 200                 writel(0, fsl_lpspi->base + IMX7ULP_TDR);
 201         else
 202                 fsl_lpspi_intctrl(fsl_lpspi, IER_TDIE);
 203 }
 204
 205 static void fsl_lpspi_read_rx_fifo(struct fsl_lpspi_data *fsl_lpspi)
 206 {
 207         while (!(readl(fsl_lpspi->base + IMX7ULP_RSR) & RSR_RXEMPTY))
 208                 fsl_lpspi->rx(fsl_lpspi);
 209 }
 210
 211 static void fsl_lpspi_set_cmd(struct fsl_lpspi_data *fsl_lpspi,
 212                               bool is_first_xfer)
 213 {
 214         u32 temp = 0;
 215
 216         temp |= fsl_lpspi->config.bpw - 1;
 217         temp |= fsl_lpspi->config.prescale << 27;
 218         temp |= (fsl_lpspi->config.mode & 0x3) << 30;
 219         temp |= (fsl_lpspi->config.chip_select & 0x3) << 24;
 220
 221         /*
 222          * Set TCR_CONT will keep SS asserted after current transfer.
 223          * For the first transfer, clear TCR_CONTC to assert SS.
 224          * For subsequent transfer, set TCR_CONTC to keep SS asserted.
 225          */
 226         temp |= TCR_CONT;
 227         if (is_first_xfer)
 228                 temp &= ~TCR_CONTC;
 229         else
 230                 temp |= TCR_CONTC;
 231
 232         writel(temp, fsl_lpspi->base + IMX7ULP_TCR);
 233
 234         dev_dbg(fsl_lpspi->dev, "TCR=0x%x\n", temp);
 235 }
 236
 237 static void fsl_lpspi_set_watermark(struct fsl_lpspi_data *fsl_lpspi)
 238 {
 239         u32 temp;
 240
 241         temp = fsl_lpspi->txfifosize >> 1 | (fsl_lpspi->rxfifosize >> 1) << 16;
 242
 243         writel(temp, fsl_lpspi->base + IMX7ULP_FCR);
 244
 245         dev_dbg(fsl_lpspi->dev, "FCR=0x%x\n", temp);
 246 }
 247
 248 static int fsl_lpspi_set_bitrate(struct fsl_lpspi_data *fsl_lpspi)
 249 {
 250         struct lpspi_config config = fsl_lpspi->config;
 251         unsigned int perclk_rate, scldiv;
 252         u8 prescale;
 253
 254         perclk_rate = clk_get_rate(fsl_lpspi->clk);
 255         for (prescale = 0; prescale < 8; prescale++) {
 256                 scldiv = perclk_rate /
 257                          (clkdivs[prescale] * config.speed_hz) - 2;
 258                 if (scldiv < 256) {
 259                         fsl_lpspi->config.prescale = prescale;
 260                         break;
 261                 }
 262         }
 263
 264         if (prescale == 8 && scldiv >= 256)
 265                 return -EINVAL;
 266
 267         writel(scldiv, fsl_lpspi->base + IMX7ULP_CCR);
 268
 269         dev_dbg(fsl_lpspi->dev, "perclk=%d, speed=%d, prescale =%d, scldiv=%d\n",
 270                 perclk_rate, config.speed_hz, prescale, scldiv);
 271
 272         return 0;
 273 }
 274
 275 static int fsl_lpspi_config(struct fsl_lpspi_data *fsl_lpspi)
 276 {
 277         u32 temp;
 278         int ret;
 279
 280         temp = CR_RST;
 281         writel(temp, fsl_lpspi->base + IMX7ULP_CR);
 282         writel(0, fsl_lpspi->base + IMX7ULP_CR);
 283
 284         ret = fsl_lpspi_set_bitrate(fsl_lpspi);
 285         if (ret)
 286                 return ret;
 287
 288         fsl_lpspi_set_watermark(fsl_lpspi);
 289
 290         temp = CFGR1_PCSCFG | CFGR1_MASTER | CFGR1_NOSTALL;
 291         if (fsl_lpspi->config.mode & SPI_CS_HIGH)
 292                 temp |= CFGR1_PCSPOL;
 293         writel(temp, fsl_lpspi->base + IMX7ULP_CFGR1);
 294
 295         temp = readl(fsl_lpspi->base + IMX7ULP_CR);
 296         temp |= CR_RRF | CR_RTF | CR_MEN;
 297         writel(temp, fsl_lpspi->base + IMX7ULP_CR);
 298
 299         return 0;
 300 }
 301
 302 static void fsl_lpspi_setup_transfer(struct spi_device *spi,
 303                                      struct spi_transfer *t)
 304 {
 305         struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(spi->master);
 306
 307         fsl_lpspi->config.mode = spi->mode;
 308         fsl_lpspi->config.bpw = t ? t->bits_per_word : spi->bits_per_word;
 309         fsl_lpspi->config.speed_hz = t ? t->speed_hz : spi->max_speed_hz;
 310         fsl_lpspi->config.chip_select = spi->chip_select;
 311
 312         if (!fsl_lpspi->config.speed_hz)
 313                 fsl_lpspi->config.speed_hz = spi->max_speed_hz;
 314         if (!fsl_lpspi->config.bpw)
 315                 fsl_lpspi->config.bpw = spi->bits_per_word;
 316
 317         /* Initialize the functions for transfer */
 318         if (fsl_lpspi->config.bpw <= 8) {
 319                 fsl_lpspi->rx = fsl_lpspi_buf_rx_u8;
 320                 fsl_lpspi->tx = fsl_lpspi_buf_tx_u8;
 321         } else if (fsl_lpspi->config.bpw <= 16) {
 322                 fsl_lpspi->rx = fsl_lpspi_buf_rx_u16;
 323                 fsl_lpspi->tx = fsl_lpspi_buf_tx_u16;
 324         } else {
 325                 fsl_lpspi->rx = fsl_lpspi_buf_rx_u32;
 326                 fsl_lpspi->tx = fsl_lpspi_buf_tx_u32;
 327         }
 328
 329         fsl_lpspi_config(fsl_lpspi);
 330 }
 331
 332 static int fsl_lpspi_transfer_one(struct spi_master *master,
 333                                   struct spi_device *spi,
 334                                   struct spi_transfer *t)
 335 {
 336         struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(master);
 337         int ret;
 338
 339         fsl_lpspi->tx_buf = t->tx_buf;
 340         fsl_lpspi->rx_buf = t->rx_buf;
 341         fsl_lpspi->remain = t->len;
 342
 343         reinit_completion(&fsl_lpspi->xfer_done);
 344         fsl_lpspi_write_tx_fifo(fsl_lpspi);
 345
 346         ret = wait_for_completion_timeout(&fsl_lpspi->xfer_done, HZ);
 347         if (!ret) {
 348                 dev_dbg(fsl_lpspi->dev, "wait for completion timeout\n");
 349                 return -ETIMEDOUT;
 350         }
 351
 352         ret = fsl_lpspi_txfifo_empty(fsl_lpspi);
 353         if (ret)
 354                 return ret;
 355
 356         fsl_lpspi_read_rx_fifo(fsl_lpspi);
 357
 358         return 0;
 359 }
 360
 361 static int fsl_lpspi_transfer_one_msg(struct spi_master *master,
 362                                       struct spi_message *msg)
 363 {
 364         struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(master);
 365         struct spi_device *spi = msg->spi;
 366         struct spi_transfer *xfer;
 367         bool is_first_xfer = true;
 368         u32 temp;
 369         int ret = 0;
 370
 371         msg->status = 0;
 372         msg->actual_length = 0;
 373
 374         list_for_each_entry(xfer, &msg->transfers, transfer_list) {
 375                 fsl_lpspi_setup_transfer(spi, xfer);
 376                 fsl_lpspi_set_cmd(fsl_lpspi, is_first_xfer);
 377
 378                 is_first_xfer = false;
 379
 380                 ret = fsl_lpspi_transfer_one(master, spi, xfer);
 381                 if (ret < 0)
 382                         goto complete;
 383
 384                 msg->actual_length += xfer->len;
 385         }
 386
 387 complete:
 388         /* de-assert SS, then finalize current message */
 389         temp = readl(fsl_lpspi->base + IMX7ULP_TCR);
 390         temp &= ~TCR_CONTC;
 391         writel(temp, fsl_lpspi->base + IMX7ULP_TCR);
 392
 393         msg->status = ret;
 394         spi_finalize_current_message(master);
 395
 396         return ret;
 397 }
 398
 399 static irqreturn_t fsl_lpspi_isr(int irq, void *dev_id)
 400 {
 401         struct fsl_lpspi_data *fsl_lpspi = dev_id;
 402         u32 temp;
 403
 404         fsl_lpspi_intctrl(fsl_lpspi, 0);
 405         temp = readl(fsl_lpspi->base + IMX7ULP_SR);
 406
 407         fsl_lpspi_read_rx_fifo(fsl_lpspi);
 408
 409         if (temp & SR_TDF) {
 410                 fsl_lpspi_write_tx_fifo(fsl_lpspi);
 411
 412                 if (!fsl_lpspi->remain)
 413                         complete(&fsl_lpspi->xfer_done);
 414
 415                 return IRQ_HANDLED;
 416         }
 417
 418         return IRQ_NONE;
 419 }
 420
 421 static int fsl_lpspi_probe(struct platform_device *pdev)
 422 {
 423         struct fsl_lpspi_data *fsl_lpspi;
 424         struct spi_master *master;
 425         struct resource *res;
 426         int ret, irq;
 427         u32 temp;
 428
 429         master = spi_alloc_master(&pdev->dev, sizeof(struct fsl_lpspi_data));
 430         if (!master)
 431                 return -ENOMEM;
 432
 433         platform_set_drvdata(pdev, master);
 434
 435         master->bits_per_word_mask = SPI_BPW_RANGE_MASK(8, 32);
 436         master->bus_num = pdev->id;
 437
 438         fsl_lpspi = spi_master_get_devdata(master);
 439         fsl_lpspi->dev = &pdev->dev;
 440
 441         master->transfer_one_message = fsl_lpspi_transfer_one_msg;
 442         master->prepare_transfer_hardware = lpspi_prepare_xfer_hardware;
 443         master->unprepare_transfer_hardware = lpspi_unprepare_xfer_hardware;
 444         master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
 445         master->flags = SPI_MASTER_MUST_RX | SPI_MASTER_MUST_TX;
 446         master->dev.of_node = pdev->dev.of_node;
 447         master->bus_num = pdev->id;
 448
 449         init_completion(&fsl_lpspi->xfer_done);
 450
 451         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 452         fsl_lpspi->base = devm_ioremap_resource(&pdev->dev, res);
 453         if (IS_ERR(fsl_lpspi->base)) {
 454                 ret = PTR_ERR(fsl_lpspi->base);
 455                 goto out_master_put;
 456         }
 457
 458         irq = platform_get_irq(pdev, 0);
 459         if (irq < 0) {
 460                 ret = irq;
 461                 goto out_master_put;
 462         }
 463
 464         ret = devm_request_irq(&pdev->dev, irq, fsl_lpspi_isr, 0,
 465                                dev_name(&pdev->dev), fsl_lpspi);
 466         if (ret) {
 467                 dev_err(&pdev->dev, "can't get irq%d: %d\n", irq, ret);
 468                 goto out_master_put;
 469         }
 470
 471         fsl_lpspi->clk = devm_clk_get(&pdev->dev, "ipg");
 472         if (IS_ERR(fsl_lpspi->clk)) {
 473                 ret = PTR_ERR(fsl_lpspi->clk);
 474                 goto out_master_put;
 475         }
 476
 477         ret = clk_prepare_enable(fsl_lpspi->clk);
 478         if (ret) {
 479                 dev_err(&pdev->dev, "can't enable lpspi clock, ret=%d\n", ret);
 480                 goto out_master_put;
 481         }
 482
 483         temp = readl(fsl_lpspi->base + IMX7ULP_PARAM);
 484         fsl_lpspi->txfifosize = 1 << (temp & 0x0f);
 485         fsl_lpspi->rxfifosize = 1 << ((temp >> 8) & 0x0f);
 486
 487         clk_disable_unprepare(fsl_lpspi->clk);
 488
 489         ret = devm_spi_register_master(&pdev->dev, master);
 490         if (ret < 0) {
 491                 dev_err(&pdev->dev, "spi_register_master error.\n");
 492                 goto out_master_put;
 493         }
 494
 495         return 0;
 496
 497 out_master_put:
 498         spi_master_put(master);
 499
 500         return ret;
 501 }
 502
 503 static int fsl_lpspi_remove(struct platform_device *pdev)
 504 {
 505         struct spi_master *master = platform_get_drvdata(pdev);
 506         struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(master);
 507
 508         clk_disable_unprepare(fsl_lpspi->clk);
 509
 510         return 0;
 511 }
 512
 513 static struct platform_driver fsl_lpspi_driver = {
 514         .driver = {
 515                 .name = DRIVER_NAME,
 516                 .of_match_table = fsl_lpspi_dt_ids,
 517         },
 518         .probe = fsl_lpspi_probe,
 519         .remove = fsl_lpspi_remove,
 520 };
 521 module_platform_driver(fsl_lpspi_driver);
 522
 523 MODULE_DESCRIPTION("LPSPI Master Controller driver");
 524 MODULE_AUTHOR("Gao Pan <pandy.gao@nxp.com>");
 525 MODULE_LICENSE("GPL");