1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Xilinx SPI controller driver (master mode only) 4 * 5 * Author: MontaVista Software, Inc. 6 * source@mvista.com 7 * 8 * Copyright (c) 2010 Secret Lab Technologies, Ltd. 9 * Copyright (c) 2009 Intel Corporation 10 * 2002-2007 (c) MontaVista Software, Inc. 11 12 */ 13 14 #include <linux/module.h> 15 #include <linux/interrupt.h> 16 #include <linux/of.h> 17 #include <linux/platform_device.h> 18 #include <linux/spi/spi.h> 19 #include <linux/spi/spi_bitbang.h> 20 #include <linux/spi/xilinx_spi.h> 21 #include <linux/io.h> 22 23 #define XILINX_SPI_MAX_CS 32 24 25 #define XILINX_SPI_NAME "xilinx_spi" 26 27 /* Register definitions as per "OPB Serial Peripheral Interface (SPI) (v1.00e) 28 * Product Specification", DS464 29 */ 30 #define XSPI_CR_OFFSET 0x60 /* Control Register */ 31 32 #define XSPI_CR_LOOP 0x01 33 #define XSPI_CR_ENABLE 0x02 34 #define XSPI_CR_MASTER_MODE 0x04 35 #define XSPI_CR_CPOL 0x08 36 #define XSPI_CR_CPHA 0x10 37 #define XSPI_CR_MODE_MASK (XSPI_CR_CPHA | XSPI_CR_CPOL | \ 38 XSPI_CR_LSB_FIRST | XSPI_CR_LOOP) 39 #define XSPI_CR_TXFIFO_RESET 0x20 40 #define XSPI_CR_RXFIFO_RESET 0x40 41 #define XSPI_CR_MANUAL_SSELECT 0x80 42 #define XSPI_CR_TRANS_INHIBIT 0x100 43 #define XSPI_CR_LSB_FIRST 0x200 44 45 #define XSPI_SR_OFFSET 0x64 /* Status Register */ 46 47 #define XSPI_SR_RX_EMPTY_MASK 0x01 /* Receive FIFO is empty */ 48 #define XSPI_SR_RX_FULL_MASK 0x02 /* Receive FIFO is full */ 49 #define XSPI_SR_TX_EMPTY_MASK 0x04 /* Transmit FIFO is empty */ 50 #define XSPI_SR_TX_FULL_MASK 0x08 /* Transmit FIFO is full */ 51 #define XSPI_SR_MODE_FAULT_MASK 0x10 /* Mode fault error */ 52 53 #define XSPI_TXD_OFFSET 0x68 /* Data Transmit Register */ 54 #define XSPI_RXD_OFFSET 0x6c /* Data Receive Register */ 55 56 #define XSPI_SSR_OFFSET 0x70 /* 32-bit Slave Select Register */ 57 58 /* Register definitions as per "OPB IPIF (v3.01c) Product Specification", DS414 59 * IPIF registers are 32 bit 60 */ 61 #define XIPIF_V123B_DGIER_OFFSET 0x1c /* IPIF global int enable reg */ 62 #define XIPIF_V123B_GINTR_ENABLE 0x80000000 63 64 #define XIPIF_V123B_IISR_OFFSET 0x20 /* IPIF interrupt status reg */ 65 #define XIPIF_V123B_IIER_OFFSET 0x28 /* IPIF interrupt enable reg */ 66 67 #define XSPI_INTR_MODE_FAULT 0x01 /* Mode fault error */ 68 #define XSPI_INTR_SLAVE_MODE_FAULT 0x02 /* Selected as slave while 69 * disabled */ 70 #define XSPI_INTR_TX_EMPTY 0x04 /* TxFIFO is empty */ 71 #define XSPI_INTR_TX_UNDERRUN 0x08 /* TxFIFO was underrun */ 72 #define XSPI_INTR_RX_FULL 0x10 /* RxFIFO is full */ 73 #define XSPI_INTR_RX_OVERRUN 0x20 /* RxFIFO was overrun */ 74 #define XSPI_INTR_TX_HALF_EMPTY 0x40 /* TxFIFO is half empty */ 75 76 #define XIPIF_V123B_RESETR_OFFSET 0x40 /* IPIF reset register */ 77 #define XIPIF_V123B_RESET_MASK 0x0a /* the value to write */ 78 79 struct xilinx_spi { 80 /* bitbang has to be first */ 81 struct spi_bitbang bitbang; 82 struct completion done; 83 void __iomem *regs; /* virt. address of the control registers */ 84 85 int irq; 86 bool force_irq; /* force irq to setup master inhibit */ 87 u8 *rx_ptr; /* pointer in the Tx buffer */ 88 const u8 *tx_ptr; /* pointer in the Rx buffer */ 89 u8 bytes_per_word; 90 int buffer_size; /* buffer size in words */ 91 u32 cs_inactive; /* Level of the CS pins when inactive*/ 92 unsigned int (*read_fn)(void __iomem *); 93 void (*write_fn)(u32, void __iomem *); 94 }; 95 96 static void xspi_write32(u32 val, void __iomem *addr) 97 { 98 iowrite32(val, addr); 99 } 100 101 static unsigned int xspi_read32(void __iomem *addr) 102 { 103 return ioread32(addr); 104 } 105 106 static void xspi_write32_be(u32 val, void __iomem *addr) 107 { 108 iowrite32be(val, addr); 109 } 110 111 static unsigned int xspi_read32_be(void __iomem *addr) 112 { 113 return ioread32be(addr); 114 } 115 116 static void xilinx_spi_tx(struct xilinx_spi *xspi) 117 { 118 u32 data = 0; 119 120 if (!xspi->tx_ptr) { 121 xspi->write_fn(0, xspi->regs + XSPI_TXD_OFFSET); 122 return; 123 } 124 125 switch (xspi->bytes_per_word) { 126 case 1: 127 data = *(u8 *)(xspi->tx_ptr); 128 break; 129 case 2: 130 data = *(u16 *)(xspi->tx_ptr); 131 break; 132 case 4: 133 data = *(u32 *)(xspi->tx_ptr); 134 break; 135 } 136 137 xspi->write_fn(data, xspi->regs + XSPI_TXD_OFFSET); 138 xspi->tx_ptr += xspi->bytes_per_word; 139 } 140 141 static void xilinx_spi_rx(struct xilinx_spi *xspi) 142 { 143 u32 data = xspi->read_fn(xspi->regs + XSPI_RXD_OFFSET); 144 145 if (!xspi->rx_ptr) 146 return; 147 148 switch (xspi->bytes_per_word) { 149 case 1: 150 *(u8 *)(xspi->rx_ptr) = data; 151 break; 152 case 2: 153 *(u16 *)(xspi->rx_ptr) = data; 154 break; 155 case 4: 156 *(u32 *)(xspi->rx_ptr) = data; 157 break; 158 } 159 160 xspi->rx_ptr += xspi->bytes_per_word; 161 } 162 163 static void xspi_init_hw(struct xilinx_spi *xspi) 164 { 165 void __iomem *regs_base = xspi->regs; 166 167 /* Reset the SPI device */ 168 xspi->write_fn(XIPIF_V123B_RESET_MASK, 169 regs_base + XIPIF_V123B_RESETR_OFFSET); 170 /* Enable the transmit empty interrupt, which we use to determine 171 * progress on the transmission. 172 */ 173 xspi->write_fn(XSPI_INTR_TX_EMPTY, 174 regs_base + XIPIF_V123B_IIER_OFFSET); 175 /* Disable the global IPIF interrupt */ 176 xspi->write_fn(0, regs_base + XIPIF_V123B_DGIER_OFFSET); 177 /* Deselect the slave on the SPI bus */ 178 xspi->write_fn(0xffff, regs_base + XSPI_SSR_OFFSET); 179 /* Disable the transmitter, enable Manual Slave Select Assertion, 180 * put SPI controller into master mode, and enable it */ 181 xspi->write_fn(XSPI_CR_MANUAL_SSELECT | XSPI_CR_MASTER_MODE | 182 XSPI_CR_ENABLE | XSPI_CR_TXFIFO_RESET | XSPI_CR_RXFIFO_RESET, 183 regs_base + XSPI_CR_OFFSET); 184 } 185 186 static void xilinx_spi_chipselect(struct spi_device *spi, int is_on) 187 { 188 struct xilinx_spi *xspi = spi_master_get_devdata(spi->master); 189 u16 cr; 190 u32 cs; 191 192 if (is_on == BITBANG_CS_INACTIVE) { 193 /* Deselect the slave on the SPI bus */ 194 xspi->write_fn(xspi->cs_inactive, xspi->regs + XSPI_SSR_OFFSET); 195 return; 196 } 197 198 /* Set the SPI clock phase and polarity */ 199 cr = xspi->read_fn(xspi->regs + XSPI_CR_OFFSET) & ~XSPI_CR_MODE_MASK; 200 if (spi->mode & SPI_CPHA) 201 cr |= XSPI_CR_CPHA; 202 if (spi->mode & SPI_CPOL) 203 cr |= XSPI_CR_CPOL; 204 if (spi->mode & SPI_LSB_FIRST) 205 cr |= XSPI_CR_LSB_FIRST; 206 if (spi->mode & SPI_LOOP) 207 cr |= XSPI_CR_LOOP; 208 xspi->write_fn(cr, xspi->regs + XSPI_CR_OFFSET); 209 210 /* We do not check spi->max_speed_hz here as the SPI clock 211 * frequency is not software programmable (the IP block design 212 * parameter) 213 */ 214 215 cs = xspi->cs_inactive; 216 cs ^= BIT(spi_get_chipselect(spi, 0)); 217 218 /* Activate the chip select */ 219 xspi->write_fn(cs, xspi->regs + XSPI_SSR_OFFSET); 220 } 221 222 /* spi_bitbang requires custom setup_transfer() to be defined if there is a 223 * custom txrx_bufs(). 224 */ 225 static int xilinx_spi_setup_transfer(struct spi_device *spi, 226 struct spi_transfer *t) 227 { 228 struct xilinx_spi *xspi = spi_master_get_devdata(spi->master); 229 230 if (spi->mode & SPI_CS_HIGH) 231 xspi->cs_inactive &= ~BIT(spi_get_chipselect(spi, 0)); 232 else 233 xspi->cs_inactive |= BIT(spi_get_chipselect(spi, 0)); 234 235 return 0; 236 } 237 238 static int xilinx_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t) 239 { 240 struct xilinx_spi *xspi = spi_master_get_devdata(spi->master); 241 int remaining_words; /* the number of words left to transfer */ 242 bool use_irq = false; 243 u16 cr = 0; 244 245 /* We get here with transmitter inhibited */ 246 247 xspi->tx_ptr = t->tx_buf; 248 xspi->rx_ptr = t->rx_buf; 249 remaining_words = t->len / xspi->bytes_per_word; 250 251 if (xspi->irq >= 0 && 252 (xspi->force_irq || remaining_words > xspi->buffer_size)) { 253 u32 isr; 254 use_irq = true; 255 /* Inhibit irq to avoid spurious irqs on tx_empty*/ 256 cr = xspi->read_fn(xspi->regs + XSPI_CR_OFFSET); 257 xspi->write_fn(cr | XSPI_CR_TRANS_INHIBIT, 258 xspi->regs + XSPI_CR_OFFSET); 259 /* ACK old irqs (if any) */ 260 isr = xspi->read_fn(xspi->regs + XIPIF_V123B_IISR_OFFSET); 261 if (isr) 262 xspi->write_fn(isr, 263 xspi->regs + XIPIF_V123B_IISR_OFFSET); 264 /* Enable the global IPIF interrupt */ 265 xspi->write_fn(XIPIF_V123B_GINTR_ENABLE, 266 xspi->regs + XIPIF_V123B_DGIER_OFFSET); 267 reinit_completion(&xspi->done); 268 } 269 270 while (remaining_words) { 271 int n_words, tx_words, rx_words; 272 u32 sr; 273 int stalled; 274 275 n_words = min(remaining_words, xspi->buffer_size); 276 277 tx_words = n_words; 278 while (tx_words--) 279 xilinx_spi_tx(xspi); 280 281 /* Start the transfer by not inhibiting the transmitter any 282 * longer 283 */ 284 285 if (use_irq) { 286 xspi->write_fn(cr, xspi->regs + XSPI_CR_OFFSET); 287 wait_for_completion(&xspi->done); 288 /* A transmit has just completed. Process received data 289 * and check for more data to transmit. Always inhibit 290 * the transmitter while the Isr refills the transmit 291 * register/FIFO, or make sure it is stopped if we're 292 * done. 293 */ 294 xspi->write_fn(cr | XSPI_CR_TRANS_INHIBIT, 295 xspi->regs + XSPI_CR_OFFSET); 296 sr = XSPI_SR_TX_EMPTY_MASK; 297 } else 298 sr = xspi->read_fn(xspi->regs + XSPI_SR_OFFSET); 299 300 /* Read out all the data from the Rx FIFO */ 301 rx_words = n_words; 302 stalled = 10; 303 while (rx_words) { 304 if (rx_words == n_words && !(stalled--) && 305 !(sr & XSPI_SR_TX_EMPTY_MASK) && 306 (sr & XSPI_SR_RX_EMPTY_MASK)) { 307 dev_err(&spi->dev, 308 "Detected stall. Check C_SPI_MODE and C_SPI_MEMORY\n"); 309 xspi_init_hw(xspi); 310 return -EIO; 311 } 312 313 if ((sr & XSPI_SR_TX_EMPTY_MASK) && (rx_words > 1)) { 314 xilinx_spi_rx(xspi); 315 rx_words--; 316 continue; 317 } 318 319 sr = xspi->read_fn(xspi->regs + XSPI_SR_OFFSET); 320 if (!(sr & XSPI_SR_RX_EMPTY_MASK)) { 321 xilinx_spi_rx(xspi); 322 rx_words--; 323 } 324 } 325 326 remaining_words -= n_words; 327 } 328 329 if (use_irq) { 330 xspi->write_fn(0, xspi->regs + XIPIF_V123B_DGIER_OFFSET); 331 xspi->write_fn(cr, xspi->regs + XSPI_CR_OFFSET); 332 } 333 334 return t->len; 335 } 336 337 338 /* This driver supports single master mode only. Hence Tx FIFO Empty 339 * is the only interrupt we care about. 340 * Receive FIFO Overrun, Transmit FIFO Underrun, Mode Fault, and Slave Mode 341 * Fault are not to happen. 342 */ 343 static irqreturn_t xilinx_spi_irq(int irq, void *dev_id) 344 { 345 struct xilinx_spi *xspi = dev_id; 346 u32 ipif_isr; 347 348 /* Get the IPIF interrupts, and clear them immediately */ 349 ipif_isr = xspi->read_fn(xspi->regs + XIPIF_V123B_IISR_OFFSET); 350 xspi->write_fn(ipif_isr, xspi->regs + XIPIF_V123B_IISR_OFFSET); 351 352 if (ipif_isr & XSPI_INTR_TX_EMPTY) { /* Transmission completed */ 353 complete(&xspi->done); 354 return IRQ_HANDLED; 355 } 356 357 return IRQ_NONE; 358 } 359 360 static int xilinx_spi_find_buffer_size(struct xilinx_spi *xspi) 361 { 362 u8 sr; 363 int n_words = 0; 364 365 /* 366 * Before the buffer_size detection we reset the core 367 * to make sure we start with a clean state. 368 */ 369 xspi->write_fn(XIPIF_V123B_RESET_MASK, 370 xspi->regs + XIPIF_V123B_RESETR_OFFSET); 371 372 /* Fill the Tx FIFO with as many words as possible */ 373 do { 374 xspi->write_fn(0, xspi->regs + XSPI_TXD_OFFSET); 375 sr = xspi->read_fn(xspi->regs + XSPI_SR_OFFSET); 376 n_words++; 377 } while (!(sr & XSPI_SR_TX_FULL_MASK)); 378 379 return n_words; 380 } 381 382 static const struct of_device_id xilinx_spi_of_match[] = { 383 { .compatible = "xlnx,axi-quad-spi-1.00.a", }, 384 { .compatible = "xlnx,xps-spi-2.00.a", }, 385 { .compatible = "xlnx,xps-spi-2.00.b", }, 386 {} 387 }; 388 MODULE_DEVICE_TABLE(of, xilinx_spi_of_match); 389 390 static int xilinx_spi_probe(struct platform_device *pdev) 391 { 392 struct xilinx_spi *xspi; 393 struct xspi_platform_data *pdata; 394 struct resource *res; 395 int ret, num_cs = 0, bits_per_word; 396 struct spi_master *master; 397 bool force_irq = false; 398 u32 tmp; 399 u8 i; 400 401 pdata = dev_get_platdata(&pdev->dev); 402 if (pdata) { 403 num_cs = pdata->num_chipselect; 404 bits_per_word = pdata->bits_per_word; 405 force_irq = pdata->force_irq; 406 } else { 407 of_property_read_u32(pdev->dev.of_node, "xlnx,num-ss-bits", 408 &num_cs); 409 ret = of_property_read_u32(pdev->dev.of_node, 410 "xlnx,num-transfer-bits", 411 &bits_per_word); 412 if (ret) 413 bits_per_word = 8; 414 } 415 416 if (!num_cs) { 417 dev_err(&pdev->dev, 418 "Missing slave select configuration data\n"); 419 return -EINVAL; 420 } 421 422 if (num_cs > XILINX_SPI_MAX_CS) { 423 dev_err(&pdev->dev, "Invalid number of spi slaves\n"); 424 return -EINVAL; 425 } 426 427 master = devm_spi_alloc_master(&pdev->dev, sizeof(struct xilinx_spi)); 428 if (!master) 429 return -ENODEV; 430 431 /* the spi->mode bits understood by this driver: */ 432 master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_LSB_FIRST | SPI_LOOP | 433 SPI_CS_HIGH; 434 435 xspi = spi_master_get_devdata(master); 436 xspi->cs_inactive = 0xffffffff; 437 xspi->bitbang.master = master; 438 xspi->bitbang.chipselect = xilinx_spi_chipselect; 439 xspi->bitbang.setup_transfer = xilinx_spi_setup_transfer; 440 xspi->bitbang.txrx_bufs = xilinx_spi_txrx_bufs; 441 init_completion(&xspi->done); 442 443 xspi->regs = devm_platform_get_and_ioremap_resource(pdev, 0, &res); 444 if (IS_ERR(xspi->regs)) 445 return PTR_ERR(xspi->regs); 446 447 master->bus_num = pdev->id; 448 master->num_chipselect = num_cs; 449 master->dev.of_node = pdev->dev.of_node; 450 451 /* 452 * Detect endianess on the IP via loop bit in CR. Detection 453 * must be done before reset is sent because incorrect reset 454 * value generates error interrupt. 455 * Setup little endian helper functions first and try to use them 456 * and check if bit was correctly setup or not. 457 */ 458 xspi->read_fn = xspi_read32; 459 xspi->write_fn = xspi_write32; 460 461 xspi->write_fn(XSPI_CR_LOOP, xspi->regs + XSPI_CR_OFFSET); 462 tmp = xspi->read_fn(xspi->regs + XSPI_CR_OFFSET); 463 tmp &= XSPI_CR_LOOP; 464 if (tmp != XSPI_CR_LOOP) { 465 xspi->read_fn = xspi_read32_be; 466 xspi->write_fn = xspi_write32_be; 467 } 468 469 master->bits_per_word_mask = SPI_BPW_MASK(bits_per_word); 470 xspi->bytes_per_word = bits_per_word / 8; 471 xspi->buffer_size = xilinx_spi_find_buffer_size(xspi); 472 473 xspi->irq = platform_get_irq(pdev, 0); 474 if (xspi->irq < 0 && xspi->irq != -ENXIO) { 475 return xspi->irq; 476 } else if (xspi->irq >= 0) { 477 /* Register for SPI Interrupt */ 478 ret = devm_request_irq(&pdev->dev, xspi->irq, xilinx_spi_irq, 0, 479 dev_name(&pdev->dev), xspi); 480 if (ret) 481 return ret; 482 483 xspi->force_irq = force_irq; 484 } 485 486 /* SPI controller initializations */ 487 xspi_init_hw(xspi); 488 489 ret = spi_bitbang_start(&xspi->bitbang); 490 if (ret) { 491 dev_err(&pdev->dev, "spi_bitbang_start FAILED\n"); 492 return ret; 493 } 494 495 dev_info(&pdev->dev, "at %pR, irq=%d\n", res, xspi->irq); 496 497 if (pdata) { 498 for (i = 0; i < pdata->num_devices; i++) 499 spi_new_device(master, pdata->devices + i); 500 } 501 502 platform_set_drvdata(pdev, master); 503 return 0; 504 } 505 506 static void xilinx_spi_remove(struct platform_device *pdev) 507 { 508 struct spi_master *master = platform_get_drvdata(pdev); 509 struct xilinx_spi *xspi = spi_master_get_devdata(master); 510 void __iomem *regs_base = xspi->regs; 511 512 spi_bitbang_stop(&xspi->bitbang); 513 514 /* Disable all the interrupts just in case */ 515 xspi->write_fn(0, regs_base + XIPIF_V123B_IIER_OFFSET); 516 /* Disable the global IPIF interrupt */ 517 xspi->write_fn(0, regs_base + XIPIF_V123B_DGIER_OFFSET); 518 519 spi_master_put(xspi->bitbang.master); 520 } 521 522 /* work with hotplug and coldplug */ 523 MODULE_ALIAS("platform:" XILINX_SPI_NAME); 524 525 static struct platform_driver xilinx_spi_driver = { 526 .probe = xilinx_spi_probe, 527 .remove_new = xilinx_spi_remove, 528 .driver = { 529 .name = XILINX_SPI_NAME, 530 .of_match_table = xilinx_spi_of_match, 531 }, 532 }; 533 module_platform_driver(xilinx_spi_driver); 534 535 MODULE_AUTHOR("MontaVista Software, Inc. <source@mvista.com>"); 536 MODULE_DESCRIPTION("Xilinx SPI driver"); 537 MODULE_LICENSE("GPL"); 538