Version:  2.0.40 2.2.26 2.4.37 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1

Linux/drivers/spi/spi-xilinx.c

  1 /*
  2  * Xilinx SPI controller driver (master mode only)
  3  *
  4  * Author: MontaVista Software, Inc.
  5  *      source@mvista.com
  6  *
  7  * Copyright (c) 2010 Secret Lab Technologies, Ltd.
  8  * Copyright (c) 2009 Intel Corporation
  9  * 2002-2007 (c) MontaVista Software, Inc.
 10 
 11  * This program is free software; you can redistribute it and/or modify
 12  * it under the terms of the GNU General Public License version 2 as
 13  * published by the Free Software Foundation.
 14  */
 15 
 16 #include <linux/module.h>
 17 #include <linux/interrupt.h>
 18 #include <linux/of.h>
 19 #include <linux/platform_device.h>
 20 #include <linux/spi/spi.h>
 21 #include <linux/spi/spi_bitbang.h>
 22 #include <linux/spi/xilinx_spi.h>
 23 #include <linux/io.h>
 24 
 25 #define XILINX_SPI_MAX_CS       32
 26 
 27 #define XILINX_SPI_NAME "xilinx_spi"
 28 
 29 /* Register definitions as per "OPB Serial Peripheral Interface (SPI) (v1.00e)
 30  * Product Specification", DS464
 31  */
 32 #define XSPI_CR_OFFSET          0x60    /* Control Register */
 33 
 34 #define XSPI_CR_LOOP            0x01
 35 #define XSPI_CR_ENABLE          0x02
 36 #define XSPI_CR_MASTER_MODE     0x04
 37 #define XSPI_CR_CPOL            0x08
 38 #define XSPI_CR_CPHA            0x10
 39 #define XSPI_CR_MODE_MASK       (XSPI_CR_CPHA | XSPI_CR_CPOL | \
 40                                  XSPI_CR_LSB_FIRST | XSPI_CR_LOOP)
 41 #define XSPI_CR_TXFIFO_RESET    0x20
 42 #define XSPI_CR_RXFIFO_RESET    0x40
 43 #define XSPI_CR_MANUAL_SSELECT  0x80
 44 #define XSPI_CR_TRANS_INHIBIT   0x100
 45 #define XSPI_CR_LSB_FIRST       0x200
 46 
 47 #define XSPI_SR_OFFSET          0x64    /* Status Register */
 48 
 49 #define XSPI_SR_RX_EMPTY_MASK   0x01    /* Receive FIFO is empty */
 50 #define XSPI_SR_RX_FULL_MASK    0x02    /* Receive FIFO is full */
 51 #define XSPI_SR_TX_EMPTY_MASK   0x04    /* Transmit FIFO is empty */
 52 #define XSPI_SR_TX_FULL_MASK    0x08    /* Transmit FIFO is full */
 53 #define XSPI_SR_MODE_FAULT_MASK 0x10    /* Mode fault error */
 54 
 55 #define XSPI_TXD_OFFSET         0x68    /* Data Transmit Register */
 56 #define XSPI_RXD_OFFSET         0x6c    /* Data Receive Register */
 57 
 58 #define XSPI_SSR_OFFSET         0x70    /* 32-bit Slave Select Register */
 59 
 60 /* Register definitions as per "OPB IPIF (v3.01c) Product Specification", DS414
 61  * IPIF registers are 32 bit
 62  */
 63 #define XIPIF_V123B_DGIER_OFFSET        0x1c    /* IPIF global int enable reg */
 64 #define XIPIF_V123B_GINTR_ENABLE        0x80000000
 65 
 66 #define XIPIF_V123B_IISR_OFFSET         0x20    /* IPIF interrupt status reg */
 67 #define XIPIF_V123B_IIER_OFFSET         0x28    /* IPIF interrupt enable reg */
 68 
 69 #define XSPI_INTR_MODE_FAULT            0x01    /* Mode fault error */
 70 #define XSPI_INTR_SLAVE_MODE_FAULT      0x02    /* Selected as slave while
 71                                                  * disabled */
 72 #define XSPI_INTR_TX_EMPTY              0x04    /* TxFIFO is empty */
 73 #define XSPI_INTR_TX_UNDERRUN           0x08    /* TxFIFO was underrun */
 74 #define XSPI_INTR_RX_FULL               0x10    /* RxFIFO is full */
 75 #define XSPI_INTR_RX_OVERRUN            0x20    /* RxFIFO was overrun */
 76 #define XSPI_INTR_TX_HALF_EMPTY         0x40    /* TxFIFO is half empty */
 77 
 78 #define XIPIF_V123B_RESETR_OFFSET       0x40    /* IPIF reset register */
 79 #define XIPIF_V123B_RESET_MASK          0x0a    /* the value to write */
 80 
 81 struct xilinx_spi {
 82         /* bitbang has to be first */
 83         struct spi_bitbang bitbang;
 84         struct completion done;
 85         void __iomem    *regs;  /* virt. address of the control registers */
 86 
 87         int             irq;
 88 
 89         u8 *rx_ptr;             /* pointer in the Tx buffer */
 90         const u8 *tx_ptr;       /* pointer in the Rx buffer */
 91         u8 bytes_per_word;
 92         int buffer_size;        /* buffer size in words */
 93         u32 cs_inactive;        /* Level of the CS pins when inactive*/
 94         unsigned int (*read_fn)(void __iomem *);
 95         void (*write_fn)(u32, void __iomem *);
 96 };
 97 
 98 static void xspi_write32(u32 val, void __iomem *addr)
 99 {
100         iowrite32(val, addr);
101 }
102 
103 static unsigned int xspi_read32(void __iomem *addr)
104 {
105         return ioread32(addr);
106 }
107 
108 static void xspi_write32_be(u32 val, void __iomem *addr)
109 {
110         iowrite32be(val, addr);
111 }
112 
113 static unsigned int xspi_read32_be(void __iomem *addr)
114 {
115         return ioread32be(addr);
116 }
117 
118 static void xilinx_spi_tx(struct xilinx_spi *xspi)
119 {
120         u32 data = 0;
121 
122         if (!xspi->tx_ptr) {
123                 xspi->write_fn(0, xspi->regs + XSPI_TXD_OFFSET);
124                 return;
125         }
126 
127         switch (xspi->bytes_per_word) {
128         case 1:
129                 data = *(u8 *)(xspi->tx_ptr);
130                 break;
131         case 2:
132                 data = *(u16 *)(xspi->tx_ptr);
133                 break;
134         case 4:
135                 data = *(u32 *)(xspi->tx_ptr);
136                 break;
137         }
138 
139         xspi->write_fn(data, xspi->regs + XSPI_TXD_OFFSET);
140         xspi->tx_ptr += xspi->bytes_per_word;
141 }
142 
143 static void xilinx_spi_rx(struct xilinx_spi *xspi)
144 {
145         u32 data = xspi->read_fn(xspi->regs + XSPI_RXD_OFFSET);
146 
147         if (!xspi->rx_ptr)
148                 return;
149 
150         switch (xspi->bytes_per_word) {
151         case 1:
152                 *(u8 *)(xspi->rx_ptr) = data;
153                 break;
154         case 2:
155                 *(u16 *)(xspi->rx_ptr) = data;
156                 break;
157         case 4:
158                 *(u32 *)(xspi->rx_ptr) = data;
159                 break;
160         }
161 
162         xspi->rx_ptr += xspi->bytes_per_word;
163 }
164 
165 static void xspi_init_hw(struct xilinx_spi *xspi)
166 {
167         void __iomem *regs_base = xspi->regs;
168 
169         /* Reset the SPI device */
170         xspi->write_fn(XIPIF_V123B_RESET_MASK,
171                 regs_base + XIPIF_V123B_RESETR_OFFSET);
172         /* Enable the transmit empty interrupt, which we use to determine
173          * progress on the transmission.
174          */
175         xspi->write_fn(XSPI_INTR_TX_EMPTY,
176                         regs_base + XIPIF_V123B_IIER_OFFSET);
177         /* Disable the global IPIF interrupt */
178         xspi->write_fn(0, regs_base + XIPIF_V123B_DGIER_OFFSET);
179         /* Deselect the slave on the SPI bus */
180         xspi->write_fn(0xffff, regs_base + XSPI_SSR_OFFSET);
181         /* Disable the transmitter, enable Manual Slave Select Assertion,
182          * put SPI controller into master mode, and enable it */
183         xspi->write_fn(XSPI_CR_MANUAL_SSELECT | XSPI_CR_MASTER_MODE |
184                 XSPI_CR_ENABLE | XSPI_CR_TXFIFO_RESET | XSPI_CR_RXFIFO_RESET,
185                 regs_base + XSPI_CR_OFFSET);
186 }
187 
188 static void xilinx_spi_chipselect(struct spi_device *spi, int is_on)
189 {
190         struct xilinx_spi *xspi = spi_master_get_devdata(spi->master);
191         u16 cr;
192         u32 cs;
193 
194         if (is_on == BITBANG_CS_INACTIVE) {
195                 /* Deselect the slave on the SPI bus */
196                 xspi->write_fn(xspi->cs_inactive, xspi->regs + XSPI_SSR_OFFSET);
197                 return;
198         }
199 
200         /* Set the SPI clock phase and polarity */
201         cr = xspi->read_fn(xspi->regs + XSPI_CR_OFFSET) & ~XSPI_CR_MODE_MASK;
202         if (spi->mode & SPI_CPHA)
203                 cr |= XSPI_CR_CPHA;
204         if (spi->mode & SPI_CPOL)
205                 cr |= XSPI_CR_CPOL;
206         if (spi->mode & SPI_LSB_FIRST)
207                 cr |= XSPI_CR_LSB_FIRST;
208         if (spi->mode & SPI_LOOP)
209                 cr |= XSPI_CR_LOOP;
210         xspi->write_fn(cr, xspi->regs + XSPI_CR_OFFSET);
211 
212         /* We do not check spi->max_speed_hz here as the SPI clock
213          * frequency is not software programmable (the IP block design
214          * parameter)
215          */
216 
217         cs = xspi->cs_inactive;
218         cs ^= BIT(spi->chip_select);
219 
220         /* Activate the chip select */
221         xspi->write_fn(cs, xspi->regs + XSPI_SSR_OFFSET);
222 }
223 
224 /* spi_bitbang requires custom setup_transfer() to be defined if there is a
225  * custom txrx_bufs().
226  */
227 static int xilinx_spi_setup_transfer(struct spi_device *spi,
228                 struct spi_transfer *t)
229 {
230         struct xilinx_spi *xspi = spi_master_get_devdata(spi->master);
231 
232         if (spi->mode & SPI_CS_HIGH)
233                 xspi->cs_inactive &= ~BIT(spi->chip_select);
234         else
235                 xspi->cs_inactive |= BIT(spi->chip_select);
236 
237         return 0;
238 }
239 
240 static int xilinx_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t)
241 {
242         struct xilinx_spi *xspi = spi_master_get_devdata(spi->master);
243         int remaining_words;    /* the number of words left to transfer */
244         bool use_irq = false;
245         u16 cr = 0;
246 
247         /* We get here with transmitter inhibited */
248 
249         xspi->tx_ptr = t->tx_buf;
250         xspi->rx_ptr = t->rx_buf;
251         remaining_words = t->len / xspi->bytes_per_word;
252         reinit_completion(&xspi->done);
253 
254         if (xspi->irq >= 0 &&  remaining_words > xspi->buffer_size) {
255                 use_irq = true;
256                 xspi->write_fn(XSPI_INTR_TX_EMPTY,
257                                 xspi->regs + XIPIF_V123B_IISR_OFFSET);
258                 /* Enable the global IPIF interrupt */
259                 xspi->write_fn(XIPIF_V123B_GINTR_ENABLE,
260                                 xspi->regs + XIPIF_V123B_DGIER_OFFSET);
261                 /* Inhibit irq to avoid spurious irqs on tx_empty*/
262                 cr = xspi->read_fn(xspi->regs + XSPI_CR_OFFSET);
263                 xspi->write_fn(cr | XSPI_CR_TRANS_INHIBIT,
264                                xspi->regs + XSPI_CR_OFFSET);
265         }
266 
267         while (remaining_words) {
268                 int n_words, tx_words, rx_words;
269 
270                 n_words = min(remaining_words, xspi->buffer_size);
271 
272                 tx_words = n_words;
273                 while (tx_words--)
274                         xilinx_spi_tx(xspi);
275 
276                 /* Start the transfer by not inhibiting the transmitter any
277                  * longer
278                  */
279 
280                 if (use_irq) {
281                         xspi->write_fn(cr, xspi->regs + XSPI_CR_OFFSET);
282                         wait_for_completion(&xspi->done);
283                 } else
284                         while (!(xspi->read_fn(xspi->regs + XSPI_SR_OFFSET) &
285                                                 XSPI_SR_TX_EMPTY_MASK))
286                                 ;
287 
288                 /* A transmit has just completed. Process received data and
289                  * check for more data to transmit. Always inhibit the
290                  * transmitter while the Isr refills the transmit register/FIFO,
291                  * or make sure it is stopped if we're done.
292                  */
293                 if (use_irq)
294                         xspi->write_fn(cr | XSPI_CR_TRANS_INHIBIT,
295                                xspi->regs + XSPI_CR_OFFSET);
296 
297                 /* Read out all the data from the Rx FIFO */
298                 rx_words = n_words;
299                 while (rx_words--)
300                         xilinx_spi_rx(xspi);
301 
302                 remaining_words -= n_words;
303         }
304 
305         if (use_irq)
306                 xspi->write_fn(0, xspi->regs + XIPIF_V123B_DGIER_OFFSET);
307 
308         return t->len;
309 }
310 
311 
312 /* This driver supports single master mode only. Hence Tx FIFO Empty
313  * is the only interrupt we care about.
314  * Receive FIFO Overrun, Transmit FIFO Underrun, Mode Fault, and Slave Mode
315  * Fault are not to happen.
316  */
317 static irqreturn_t xilinx_spi_irq(int irq, void *dev_id)
318 {
319         struct xilinx_spi *xspi = dev_id;
320         u32 ipif_isr;
321 
322         /* Get the IPIF interrupts, and clear them immediately */
323         ipif_isr = xspi->read_fn(xspi->regs + XIPIF_V123B_IISR_OFFSET);
324         xspi->write_fn(ipif_isr, xspi->regs + XIPIF_V123B_IISR_OFFSET);
325 
326         if (ipif_isr & XSPI_INTR_TX_EMPTY) {    /* Transmission completed */
327                 complete(&xspi->done);
328         }
329 
330         return IRQ_HANDLED;
331 }
332 
333 static int xilinx_spi_find_buffer_size(struct xilinx_spi *xspi)
334 {
335         u8 sr;
336         int n_words = 0;
337 
338         /*
339          * Before the buffer_size detection we reset the core
340          * to make sure we start with a clean state.
341          */
342         xspi->write_fn(XIPIF_V123B_RESET_MASK,
343                 xspi->regs + XIPIF_V123B_RESETR_OFFSET);
344 
345         /* Fill the Tx FIFO with as many words as possible */
346         do {
347                 xspi->write_fn(0, xspi->regs + XSPI_TXD_OFFSET);
348                 sr = xspi->read_fn(xspi->regs + XSPI_SR_OFFSET);
349                 n_words++;
350         } while (!(sr & XSPI_SR_TX_FULL_MASK));
351 
352         return n_words;
353 }
354 
355 static const struct of_device_id xilinx_spi_of_match[] = {
356         { .compatible = "xlnx,xps-spi-2.00.a", },
357         { .compatible = "xlnx,xps-spi-2.00.b", },
358         {}
359 };
360 MODULE_DEVICE_TABLE(of, xilinx_spi_of_match);
361 
362 static int xilinx_spi_probe(struct platform_device *pdev)
363 {
364         struct xilinx_spi *xspi;
365         struct xspi_platform_data *pdata;
366         struct resource *res;
367         int ret, num_cs = 0, bits_per_word = 8;
368         struct spi_master *master;
369         u32 tmp;
370         u8 i;
371 
372         pdata = dev_get_platdata(&pdev->dev);
373         if (pdata) {
374                 num_cs = pdata->num_chipselect;
375                 bits_per_word = pdata->bits_per_word;
376         } else {
377                 of_property_read_u32(pdev->dev.of_node, "xlnx,num-ss-bits",
378                                           &num_cs);
379         }
380 
381         if (!num_cs) {
382                 dev_err(&pdev->dev,
383                         "Missing slave select configuration data\n");
384                 return -EINVAL;
385         }
386 
387         if (num_cs > XILINX_SPI_MAX_CS) {
388                 dev_err(&pdev->dev, "Invalid number of spi slaves\n");
389                 return -EINVAL;
390         }
391 
392         master = spi_alloc_master(&pdev->dev, sizeof(struct xilinx_spi));
393         if (!master)
394                 return -ENODEV;
395 
396         /* the spi->mode bits understood by this driver: */
397         master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_LSB_FIRST | SPI_LOOP |
398                             SPI_CS_HIGH;
399 
400         xspi = spi_master_get_devdata(master);
401         xspi->cs_inactive = 0xffffffff;
402         xspi->bitbang.master = master;
403         xspi->bitbang.chipselect = xilinx_spi_chipselect;
404         xspi->bitbang.setup_transfer = xilinx_spi_setup_transfer;
405         xspi->bitbang.txrx_bufs = xilinx_spi_txrx_bufs;
406         init_completion(&xspi->done);
407 
408         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
409         xspi->regs = devm_ioremap_resource(&pdev->dev, res);
410         if (IS_ERR(xspi->regs)) {
411                 ret = PTR_ERR(xspi->regs);
412                 goto put_master;
413         }
414 
415         master->bus_num = pdev->id;
416         master->num_chipselect = num_cs;
417         master->dev.of_node = pdev->dev.of_node;
418 
419         /*
420          * Detect endianess on the IP via loop bit in CR. Detection
421          * must be done before reset is sent because incorrect reset
422          * value generates error interrupt.
423          * Setup little endian helper functions first and try to use them
424          * and check if bit was correctly setup or not.
425          */
426         xspi->read_fn = xspi_read32;
427         xspi->write_fn = xspi_write32;
428 
429         xspi->write_fn(XSPI_CR_LOOP, xspi->regs + XSPI_CR_OFFSET);
430         tmp = xspi->read_fn(xspi->regs + XSPI_CR_OFFSET);
431         tmp &= XSPI_CR_LOOP;
432         if (tmp != XSPI_CR_LOOP) {
433                 xspi->read_fn = xspi_read32_be;
434                 xspi->write_fn = xspi_write32_be;
435         }
436 
437         master->bits_per_word_mask = SPI_BPW_MASK(bits_per_word);
438         xspi->bytes_per_word = bits_per_word / 8;
439         xspi->buffer_size = xilinx_spi_find_buffer_size(xspi);
440 
441         xspi->irq = platform_get_irq(pdev, 0);
442         if (xspi->irq >= 0) {
443                 /* Register for SPI Interrupt */
444                 ret = devm_request_irq(&pdev->dev, xspi->irq, xilinx_spi_irq, 0,
445                                 dev_name(&pdev->dev), xspi);
446                 if (ret)
447                         goto put_master;
448         }
449 
450         /* SPI controller initializations */
451         xspi_init_hw(xspi);
452 
453         ret = spi_bitbang_start(&xspi->bitbang);
454         if (ret) {
455                 dev_err(&pdev->dev, "spi_bitbang_start FAILED\n");
456                 goto put_master;
457         }
458 
459         dev_info(&pdev->dev, "at 0x%08llX mapped to 0x%p, irq=%d\n",
460                 (unsigned long long)res->start, xspi->regs, xspi->irq);
461 
462         if (pdata) {
463                 for (i = 0; i < pdata->num_devices; i++)
464                         spi_new_device(master, pdata->devices + i);
465         }
466 
467         platform_set_drvdata(pdev, master);
468         return 0;
469 
470 put_master:
471         spi_master_put(master);
472 
473         return ret;
474 }
475 
476 static int xilinx_spi_remove(struct platform_device *pdev)
477 {
478         struct spi_master *master = platform_get_drvdata(pdev);
479         struct xilinx_spi *xspi = spi_master_get_devdata(master);
480         void __iomem *regs_base = xspi->regs;
481 
482         spi_bitbang_stop(&xspi->bitbang);
483 
484         /* Disable all the interrupts just in case */
485         xspi->write_fn(0, regs_base + XIPIF_V123B_IIER_OFFSET);
486         /* Disable the global IPIF interrupt */
487         xspi->write_fn(0, regs_base + XIPIF_V123B_DGIER_OFFSET);
488 
489         spi_master_put(xspi->bitbang.master);
490 
491         return 0;
492 }
493 
494 /* work with hotplug and coldplug */
495 MODULE_ALIAS("platform:" XILINX_SPI_NAME);
496 
497 static struct platform_driver xilinx_spi_driver = {
498         .probe = xilinx_spi_probe,
499         .remove = xilinx_spi_remove,
500         .driver = {
501                 .name = XILINX_SPI_NAME,
502                 .of_match_table = xilinx_spi_of_match,
503         },
504 };
505 module_platform_driver(xilinx_spi_driver);
506 
507 MODULE_AUTHOR("MontaVista Software, Inc. <source@mvista.com>");
508 MODULE_DESCRIPTION("Xilinx SPI driver");
509 MODULE_LICENSE("GPL");
510 

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