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 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->chip_select); 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->chip_select); 232 else 233 xspi->cs_inactive |= BIT(spi->chip_select); 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 && remaining_words > xspi->buffer_size) { 252 u32 isr; 253 use_irq = true; 254 /* Inhibit irq to avoid spurious irqs on tx_empty*/ 255 cr = xspi->read_fn(xspi->regs + XSPI_CR_OFFSET); 256 xspi->write_fn(cr | XSPI_CR_TRANS_INHIBIT, 257 xspi->regs + XSPI_CR_OFFSET); 258 /* ACK old irqs (if any) */ 259 isr = xspi->read_fn(xspi->regs + XIPIF_V123B_IISR_OFFSET); 260 if (isr) 261 xspi->write_fn(isr, 262 xspi->regs + XIPIF_V123B_IISR_OFFSET); 263 /* Enable the global IPIF interrupt */ 264 xspi->write_fn(XIPIF_V123B_GINTR_ENABLE, 265 xspi->regs + XIPIF_V123B_DGIER_OFFSET); 266 reinit_completion(&xspi->done); 267 } 268 269 while (remaining_words) { 270 int n_words, tx_words, rx_words; 271 u32 sr; 272 int stalled; 273 274 n_words = min(remaining_words, xspi->buffer_size); 275 276 tx_words = n_words; 277 while (tx_words--) 278 xilinx_spi_tx(xspi); 279 280 /* Start the transfer by not inhibiting the transmitter any 281 * longer 282 */ 283 284 if (use_irq) { 285 xspi->write_fn(cr, xspi->regs + XSPI_CR_OFFSET); 286 wait_for_completion(&xspi->done); 287 /* A transmit has just completed. Process received data 288 * and check for more data to transmit. Always inhibit 289 * the transmitter while the Isr refills the transmit 290 * register/FIFO, or make sure it is stopped if we're 291 * done. 292 */ 293 xspi->write_fn(cr | XSPI_CR_TRANS_INHIBIT, 294 xspi->regs + XSPI_CR_OFFSET); 295 sr = XSPI_SR_TX_EMPTY_MASK; 296 } else 297 sr = xspi->read_fn(xspi->regs + XSPI_SR_OFFSET); 298 299 /* Read out all the data from the Rx FIFO */ 300 rx_words = n_words; 301 stalled = 10; 302 while (rx_words) { 303 if (rx_words == n_words && !(stalled--) && 304 !(sr & XSPI_SR_TX_EMPTY_MASK) && 305 (sr & XSPI_SR_RX_EMPTY_MASK)) { 306 dev_err(&spi->dev, 307 "Detected stall. Check C_SPI_MODE and C_SPI_MEMORY\n"); 308 xspi_init_hw(xspi); 309 return -EIO; 310 } 311 312 if ((sr & XSPI_SR_TX_EMPTY_MASK) && (rx_words > 1)) { 313 xilinx_spi_rx(xspi); 314 rx_words--; 315 continue; 316 } 317 318 sr = xspi->read_fn(xspi->regs + XSPI_SR_OFFSET); 319 if (!(sr & XSPI_SR_RX_EMPTY_MASK)) { 320 xilinx_spi_rx(xspi); 321 rx_words--; 322 } 323 } 324 325 remaining_words -= n_words; 326 } 327 328 if (use_irq) { 329 xspi->write_fn(0, xspi->regs + XIPIF_V123B_DGIER_OFFSET); 330 xspi->write_fn(cr, xspi->regs + XSPI_CR_OFFSET); 331 } 332 333 return t->len; 334 } 335 336 337 /* This driver supports single master mode only. Hence Tx FIFO Empty 338 * is the only interrupt we care about. 339 * Receive FIFO Overrun, Transmit FIFO Underrun, Mode Fault, and Slave Mode 340 * Fault are not to happen. 341 */ 342 static irqreturn_t xilinx_spi_irq(int irq, void *dev_id) 343 { 344 struct xilinx_spi *xspi = dev_id; 345 u32 ipif_isr; 346 347 /* Get the IPIF interrupts, and clear them immediately */ 348 ipif_isr = xspi->read_fn(xspi->regs + XIPIF_V123B_IISR_OFFSET); 349 xspi->write_fn(ipif_isr, xspi->regs + XIPIF_V123B_IISR_OFFSET); 350 351 if (ipif_isr & XSPI_INTR_TX_EMPTY) { /* Transmission completed */ 352 complete(&xspi->done); 353 return IRQ_HANDLED; 354 } 355 356 return IRQ_NONE; 357 } 358 359 static int xilinx_spi_find_buffer_size(struct xilinx_spi *xspi) 360 { 361 u8 sr; 362 int n_words = 0; 363 364 /* 365 * Before the buffer_size detection we reset the core 366 * to make sure we start with a clean state. 367 */ 368 xspi->write_fn(XIPIF_V123B_RESET_MASK, 369 xspi->regs + XIPIF_V123B_RESETR_OFFSET); 370 371 /* Fill the Tx FIFO with as many words as possible */ 372 do { 373 xspi->write_fn(0, xspi->regs + XSPI_TXD_OFFSET); 374 sr = xspi->read_fn(xspi->regs + XSPI_SR_OFFSET); 375 n_words++; 376 } while (!(sr & XSPI_SR_TX_FULL_MASK)); 377 378 return n_words; 379 } 380 381 static const struct of_device_id xilinx_spi_of_match[] = { 382 { .compatible = "xlnx,axi-quad-spi-1.00.a", }, 383 { .compatible = "xlnx,xps-spi-2.00.a", }, 384 { .compatible = "xlnx,xps-spi-2.00.b", }, 385 {} 386 }; 387 MODULE_DEVICE_TABLE(of, xilinx_spi_of_match); 388 389 static int xilinx_spi_probe(struct platform_device *pdev) 390 { 391 struct xilinx_spi *xspi; 392 struct xspi_platform_data *pdata; 393 struct resource *res; 394 int ret, num_cs = 0, bits_per_word; 395 struct spi_master *master; 396 u32 tmp; 397 u8 i; 398 399 pdata = dev_get_platdata(&pdev->dev); 400 if (pdata) { 401 num_cs = pdata->num_chipselect; 402 bits_per_word = pdata->bits_per_word; 403 } else { 404 of_property_read_u32(pdev->dev.of_node, "xlnx,num-ss-bits", 405 &num_cs); 406 ret = of_property_read_u32(pdev->dev.of_node, 407 "xlnx,num-transfer-bits", 408 &bits_per_word); 409 if (ret) 410 bits_per_word = 8; 411 } 412 413 if (!num_cs) { 414 dev_err(&pdev->dev, 415 "Missing slave select configuration data\n"); 416 return -EINVAL; 417 } 418 419 if (num_cs > XILINX_SPI_MAX_CS) { 420 dev_err(&pdev->dev, "Invalid number of spi slaves\n"); 421 return -EINVAL; 422 } 423 424 master = devm_spi_alloc_master(&pdev->dev, sizeof(struct xilinx_spi)); 425 if (!master) 426 return -ENODEV; 427 428 /* the spi->mode bits understood by this driver: */ 429 master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_LSB_FIRST | SPI_LOOP | 430 SPI_CS_HIGH; 431 432 xspi = spi_master_get_devdata(master); 433 xspi->cs_inactive = 0xffffffff; 434 xspi->bitbang.master = master; 435 xspi->bitbang.chipselect = xilinx_spi_chipselect; 436 xspi->bitbang.setup_transfer = xilinx_spi_setup_transfer; 437 xspi->bitbang.txrx_bufs = xilinx_spi_txrx_bufs; 438 init_completion(&xspi->done); 439 440 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 441 xspi->regs = devm_ioremap_resource(&pdev->dev, res); 442 if (IS_ERR(xspi->regs)) 443 return PTR_ERR(xspi->regs); 444 445 master->bus_num = pdev->id; 446 master->num_chipselect = num_cs; 447 master->dev.of_node = pdev->dev.of_node; 448 449 /* 450 * Detect endianess on the IP via loop bit in CR. Detection 451 * must be done before reset is sent because incorrect reset 452 * value generates error interrupt. 453 * Setup little endian helper functions first and try to use them 454 * and check if bit was correctly setup or not. 455 */ 456 xspi->read_fn = xspi_read32; 457 xspi->write_fn = xspi_write32; 458 459 xspi->write_fn(XSPI_CR_LOOP, xspi->regs + XSPI_CR_OFFSET); 460 tmp = xspi->read_fn(xspi->regs + XSPI_CR_OFFSET); 461 tmp &= XSPI_CR_LOOP; 462 if (tmp != XSPI_CR_LOOP) { 463 xspi->read_fn = xspi_read32_be; 464 xspi->write_fn = xspi_write32_be; 465 } 466 467 master->bits_per_word_mask = SPI_BPW_MASK(bits_per_word); 468 xspi->bytes_per_word = bits_per_word / 8; 469 xspi->buffer_size = xilinx_spi_find_buffer_size(xspi); 470 471 xspi->irq = platform_get_irq(pdev, 0); 472 if (xspi->irq < 0 && xspi->irq != -ENXIO) { 473 return xspi->irq; 474 } else if (xspi->irq >= 0) { 475 /* Register for SPI Interrupt */ 476 ret = devm_request_irq(&pdev->dev, xspi->irq, xilinx_spi_irq, 0, 477 dev_name(&pdev->dev), xspi); 478 if (ret) 479 return ret; 480 } 481 482 /* SPI controller initializations */ 483 xspi_init_hw(xspi); 484 485 ret = spi_bitbang_start(&xspi->bitbang); 486 if (ret) { 487 dev_err(&pdev->dev, "spi_bitbang_start FAILED\n"); 488 return ret; 489 } 490 491 dev_info(&pdev->dev, "at %pR, irq=%d\n", res, xspi->irq); 492 493 if (pdata) { 494 for (i = 0; i < pdata->num_devices; i++) 495 spi_new_device(master, pdata->devices + i); 496 } 497 498 platform_set_drvdata(pdev, master); 499 return 0; 500 } 501 502 static int xilinx_spi_remove(struct platform_device *pdev) 503 { 504 struct spi_master *master = platform_get_drvdata(pdev); 505 struct xilinx_spi *xspi = spi_master_get_devdata(master); 506 void __iomem *regs_base = xspi->regs; 507 508 spi_bitbang_stop(&xspi->bitbang); 509 510 /* Disable all the interrupts just in case */ 511 xspi->write_fn(0, regs_base + XIPIF_V123B_IIER_OFFSET); 512 /* Disable the global IPIF interrupt */ 513 xspi->write_fn(0, regs_base + XIPIF_V123B_DGIER_OFFSET); 514 515 spi_master_put(xspi->bitbang.master); 516 517 return 0; 518 } 519 520 /* work with hotplug and coldplug */ 521 MODULE_ALIAS("platform:" XILINX_SPI_NAME); 522 523 static struct platform_driver xilinx_spi_driver = { 524 .probe = xilinx_spi_probe, 525 .remove = xilinx_spi_remove, 526 .driver = { 527 .name = XILINX_SPI_NAME, 528 .of_match_table = xilinx_spi_of_match, 529 }, 530 }; 531 module_platform_driver(xilinx_spi_driver); 532 533 MODULE_AUTHOR("MontaVista Software, Inc. <source@mvista.com>"); 534 MODULE_DESCRIPTION("Xilinx SPI driver"); 535 MODULE_LICENSE("GPL"); 536