1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * MPC512x PSC in SPI mode driver.
4 *
5 * Copyright (C) 2007,2008 Freescale Semiconductor Inc.
6 * Original port from 52xx driver:
7 * Hongjun Chen <hong-jun.chen@freescale.com>
8 *
9 * Fork of mpc52xx_psc_spi.c:
10 * Copyright (C) 2006 TOPTICA Photonics AG., Dragos Carp
11 */
12
13 #include <linux/module.h>
14 #include <linux/kernel.h>
15 #include <linux/errno.h>
16 #include <linux/interrupt.h>
17 #include <linux/completion.h>
18 #include <linux/io.h>
19 #include <linux/platform_device.h>
20 #include <linux/property.h>
21 #include <linux/delay.h>
22 #include <linux/clk.h>
23 #include <linux/spi/spi.h>
24 #include <asm/mpc52xx_psc.h>
25
26 enum {
27 TYPE_MPC5121,
28 TYPE_MPC5125,
29 };
30
31 /*
32 * This macro abstracts the differences in the PSC register layout between
33 * MPC5121 (which uses a struct mpc52xx_psc) and MPC5125 (using mpc5125_psc).
34 */
35 #define psc_addr(mps, regname) ({ \
36 void *__ret = NULL; \
37 switch (mps->type) { \
38 case TYPE_MPC5121: { \
39 struct mpc52xx_psc __iomem *psc = mps->psc; \
40 __ret = &psc->regname; \
41 }; \
42 break; \
43 case TYPE_MPC5125: { \
44 struct mpc5125_psc __iomem *psc = mps->psc; \
45 __ret = &psc->regname; \
46 }; \
47 break; \
48 } \
49 __ret; })
50
51 struct mpc512x_psc_spi {
52 /* driver internal data */
53 int type;
54 void __iomem *psc;
55 struct mpc512x_psc_fifo __iomem *fifo;
56 int irq;
57 u8 bits_per_word;
58 u32 mclk_rate;
59
60 struct completion txisrdone;
61 };
62
63 /* controller state */
64 struct mpc512x_psc_spi_cs {
65 int bits_per_word;
66 int speed_hz;
67 };
68
69 /* set clock freq, clock ramp, bits per work
70 * if t is NULL then reset the values to the default values
71 */
mpc512x_psc_spi_transfer_setup(struct spi_device * spi,struct spi_transfer * t)72 static int mpc512x_psc_spi_transfer_setup(struct spi_device *spi,
73 struct spi_transfer *t)
74 {
75 struct mpc512x_psc_spi_cs *cs = spi->controller_state;
76
77 cs->speed_hz = (t && t->speed_hz)
78 ? t->speed_hz : spi->max_speed_hz;
79 cs->bits_per_word = (t && t->bits_per_word)
80 ? t->bits_per_word : spi->bits_per_word;
81 cs->bits_per_word = ((cs->bits_per_word + 7) / 8) * 8;
82 return 0;
83 }
84
mpc512x_psc_spi_activate_cs(struct spi_device * spi)85 static void mpc512x_psc_spi_activate_cs(struct spi_device *spi)
86 {
87 struct mpc512x_psc_spi_cs *cs = spi->controller_state;
88 struct mpc512x_psc_spi *mps = spi_master_get_devdata(spi->master);
89 u32 sicr;
90 u32 ccr;
91 int speed;
92 u16 bclkdiv;
93
94 sicr = in_be32(psc_addr(mps, sicr));
95
96 /* Set clock phase and polarity */
97 if (spi->mode & SPI_CPHA)
98 sicr |= 0x00001000;
99 else
100 sicr &= ~0x00001000;
101
102 if (spi->mode & SPI_CPOL)
103 sicr |= 0x00002000;
104 else
105 sicr &= ~0x00002000;
106
107 if (spi->mode & SPI_LSB_FIRST)
108 sicr |= 0x10000000;
109 else
110 sicr &= ~0x10000000;
111 out_be32(psc_addr(mps, sicr), sicr);
112
113 ccr = in_be32(psc_addr(mps, ccr));
114 ccr &= 0xFF000000;
115 speed = cs->speed_hz;
116 if (!speed)
117 speed = 1000000; /* default 1MHz */
118 bclkdiv = (mps->mclk_rate / speed) - 1;
119
120 ccr |= (((bclkdiv & 0xff) << 16) | (((bclkdiv >> 8) & 0xff) << 8));
121 out_be32(psc_addr(mps, ccr), ccr);
122 mps->bits_per_word = cs->bits_per_word;
123
124 if (spi_get_csgpiod(spi, 0)) {
125 /* gpiolib will deal with the inversion */
126 gpiod_set_value(spi_get_csgpiod(spi, 0), 1);
127 }
128 }
129
mpc512x_psc_spi_deactivate_cs(struct spi_device * spi)130 static void mpc512x_psc_spi_deactivate_cs(struct spi_device *spi)
131 {
132 if (spi_get_csgpiod(spi, 0)) {
133 /* gpiolib will deal with the inversion */
134 gpiod_set_value(spi_get_csgpiod(spi, 0), 0);
135 }
136 }
137
138 /* extract and scale size field in txsz or rxsz */
139 #define MPC512x_PSC_FIFO_SZ(sz) ((sz & 0x7ff) << 2);
140
141 #define EOFBYTE 1
142
mpc512x_psc_spi_transfer_rxtx(struct spi_device * spi,struct spi_transfer * t)143 static int mpc512x_psc_spi_transfer_rxtx(struct spi_device *spi,
144 struct spi_transfer *t)
145 {
146 struct mpc512x_psc_spi *mps = spi_master_get_devdata(spi->master);
147 struct mpc512x_psc_fifo __iomem *fifo = mps->fifo;
148 size_t tx_len = t->len;
149 size_t rx_len = t->len;
150 u8 *tx_buf = (u8 *)t->tx_buf;
151 u8 *rx_buf = (u8 *)t->rx_buf;
152
153 if (!tx_buf && !rx_buf && t->len)
154 return -EINVAL;
155
156 while (rx_len || tx_len) {
157 size_t txcount;
158 u8 data;
159 size_t fifosz;
160 size_t rxcount;
161 int rxtries;
162
163 /*
164 * send the TX bytes in as large a chunk as possible
165 * but neither exceed the TX nor the RX FIFOs
166 */
167 fifosz = MPC512x_PSC_FIFO_SZ(in_be32(&fifo->txsz));
168 txcount = min(fifosz, tx_len);
169 fifosz = MPC512x_PSC_FIFO_SZ(in_be32(&fifo->rxsz));
170 fifosz -= in_be32(&fifo->rxcnt) + 1;
171 txcount = min(fifosz, txcount);
172 if (txcount) {
173
174 /* fill the TX FIFO */
175 while (txcount-- > 0) {
176 data = tx_buf ? *tx_buf++ : 0;
177 if (tx_len == EOFBYTE && t->cs_change)
178 setbits32(&fifo->txcmd,
179 MPC512x_PSC_FIFO_EOF);
180 out_8(&fifo->txdata_8, data);
181 tx_len--;
182 }
183
184 /* have the ISR trigger when the TX FIFO is empty */
185 reinit_completion(&mps->txisrdone);
186 out_be32(&fifo->txisr, MPC512x_PSC_FIFO_EMPTY);
187 out_be32(&fifo->tximr, MPC512x_PSC_FIFO_EMPTY);
188 wait_for_completion(&mps->txisrdone);
189 }
190
191 /*
192 * consume as much RX data as the FIFO holds, while we
193 * iterate over the transfer's TX data length
194 *
195 * only insist in draining all the remaining RX bytes
196 * when the TX bytes were exhausted (that's at the very
197 * end of this transfer, not when still iterating over
198 * the transfer's chunks)
199 */
200 rxtries = 50;
201 do {
202
203 /*
204 * grab whatever was in the FIFO when we started
205 * looking, don't bother fetching what was added to
206 * the FIFO while we read from it -- we'll return
207 * here eventually and prefer sending out remaining
208 * TX data
209 */
210 fifosz = in_be32(&fifo->rxcnt);
211 rxcount = min(fifosz, rx_len);
212 while (rxcount-- > 0) {
213 data = in_8(&fifo->rxdata_8);
214 if (rx_buf)
215 *rx_buf++ = data;
216 rx_len--;
217 }
218
219 /*
220 * come back later if there still is TX data to send,
221 * bail out of the RX drain loop if all of the TX data
222 * was sent and all of the RX data was received (i.e.
223 * when the transmission has completed)
224 */
225 if (tx_len)
226 break;
227 if (!rx_len)
228 break;
229
230 /*
231 * TX data transmission has completed while RX data
232 * is still pending -- that's a transient situation
233 * which depends on wire speed and specific
234 * hardware implementation details (buffering) yet
235 * should resolve very quickly
236 *
237 * just yield for a moment to not hog the CPU for
238 * too long when running SPI at low speed
239 *
240 * the timeout range is rather arbitrary and tries
241 * to balance throughput against system load; the
242 * chosen values result in a minimal timeout of 50
243 * times 10us and thus work at speeds as low as
244 * some 20kbps, while the maximum timeout at the
245 * transfer's end could be 5ms _if_ nothing else
246 * ticks in the system _and_ RX data still wasn't
247 * received, which only occurs in situations that
248 * are exceptional; removing the unpredictability
249 * of the timeout either decreases throughput
250 * (longer timeouts), or puts more load on the
251 * system (fixed short timeouts) or requires the
252 * use of a timeout API instead of a counter and an
253 * unknown inner delay
254 */
255 usleep_range(10, 100);
256
257 } while (--rxtries > 0);
258 if (!tx_len && rx_len && !rxtries) {
259 /*
260 * not enough RX bytes even after several retries
261 * and the resulting rather long timeout?
262 */
263 rxcount = in_be32(&fifo->rxcnt);
264 dev_warn(&spi->dev,
265 "short xfer, missing %zd RX bytes, FIFO level %zd\n",
266 rx_len, rxcount);
267 }
268
269 /*
270 * drain and drop RX data which "should not be there" in
271 * the first place, for undisturbed transmission this turns
272 * into a NOP (except for the FIFO level fetch)
273 */
274 if (!tx_len && !rx_len) {
275 while (in_be32(&fifo->rxcnt))
276 in_8(&fifo->rxdata_8);
277 }
278
279 }
280 return 0;
281 }
282
mpc512x_psc_spi_msg_xfer(struct spi_master * master,struct spi_message * m)283 static int mpc512x_psc_spi_msg_xfer(struct spi_master *master,
284 struct spi_message *m)
285 {
286 struct spi_device *spi;
287 unsigned cs_change;
288 int status;
289 struct spi_transfer *t;
290
291 spi = m->spi;
292 cs_change = 1;
293 status = 0;
294 list_for_each_entry(t, &m->transfers, transfer_list) {
295 status = mpc512x_psc_spi_transfer_setup(spi, t);
296 if (status < 0)
297 break;
298
299 if (cs_change)
300 mpc512x_psc_spi_activate_cs(spi);
301 cs_change = t->cs_change;
302
303 status = mpc512x_psc_spi_transfer_rxtx(spi, t);
304 if (status)
305 break;
306 m->actual_length += t->len;
307
308 spi_transfer_delay_exec(t);
309
310 if (cs_change)
311 mpc512x_psc_spi_deactivate_cs(spi);
312 }
313
314 m->status = status;
315 if (m->complete)
316 m->complete(m->context);
317
318 if (status || !cs_change)
319 mpc512x_psc_spi_deactivate_cs(spi);
320
321 mpc512x_psc_spi_transfer_setup(spi, NULL);
322
323 spi_finalize_current_message(master);
324 return status;
325 }
326
mpc512x_psc_spi_prep_xfer_hw(struct spi_master * master)327 static int mpc512x_psc_spi_prep_xfer_hw(struct spi_master *master)
328 {
329 struct mpc512x_psc_spi *mps = spi_master_get_devdata(master);
330
331 dev_dbg(&master->dev, "%s()\n", __func__);
332
333 /* Zero MR2 */
334 in_8(psc_addr(mps, mr2));
335 out_8(psc_addr(mps, mr2), 0x0);
336
337 /* enable transmitter/receiver */
338 out_8(psc_addr(mps, command), MPC52xx_PSC_TX_ENABLE | MPC52xx_PSC_RX_ENABLE);
339
340 return 0;
341 }
342
mpc512x_psc_spi_unprep_xfer_hw(struct spi_master * master)343 static int mpc512x_psc_spi_unprep_xfer_hw(struct spi_master *master)
344 {
345 struct mpc512x_psc_spi *mps = spi_master_get_devdata(master);
346 struct mpc512x_psc_fifo __iomem *fifo = mps->fifo;
347
348 dev_dbg(&master->dev, "%s()\n", __func__);
349
350 /* disable transmitter/receiver and fifo interrupt */
351 out_8(psc_addr(mps, command), MPC52xx_PSC_TX_DISABLE | MPC52xx_PSC_RX_DISABLE);
352 out_be32(&fifo->tximr, 0);
353
354 return 0;
355 }
356
mpc512x_psc_spi_setup(struct spi_device * spi)357 static int mpc512x_psc_spi_setup(struct spi_device *spi)
358 {
359 struct mpc512x_psc_spi_cs *cs = spi->controller_state;
360
361 if (spi->bits_per_word % 8)
362 return -EINVAL;
363
364 if (!cs) {
365 cs = kzalloc(sizeof(*cs), GFP_KERNEL);
366 if (!cs)
367 return -ENOMEM;
368
369 spi->controller_state = cs;
370 }
371
372 cs->bits_per_word = spi->bits_per_word;
373 cs->speed_hz = spi->max_speed_hz;
374
375 return 0;
376 }
377
mpc512x_psc_spi_cleanup(struct spi_device * spi)378 static void mpc512x_psc_spi_cleanup(struct spi_device *spi)
379 {
380 kfree(spi->controller_state);
381 }
382
mpc512x_psc_spi_port_config(struct spi_master * master,struct mpc512x_psc_spi * mps)383 static int mpc512x_psc_spi_port_config(struct spi_master *master,
384 struct mpc512x_psc_spi *mps)
385 {
386 struct mpc512x_psc_fifo __iomem *fifo = mps->fifo;
387 u32 sicr;
388 u32 ccr;
389 int speed;
390 u16 bclkdiv;
391
392 /* Reset the PSC into a known state */
393 out_8(psc_addr(mps, command), MPC52xx_PSC_RST_RX);
394 out_8(psc_addr(mps, command), MPC52xx_PSC_RST_TX);
395 out_8(psc_addr(mps, command), MPC52xx_PSC_TX_DISABLE | MPC52xx_PSC_RX_DISABLE);
396
397 /* Disable psc interrupts all useful interrupts are in fifo */
398 out_be16(psc_addr(mps, isr_imr.imr), 0);
399
400 /* Disable fifo interrupts, will be enabled later */
401 out_be32(&fifo->tximr, 0);
402 out_be32(&fifo->rximr, 0);
403
404 /* Setup fifo slice address and size */
405 /*out_be32(&fifo->txsz, 0x0fe00004);*/
406 /*out_be32(&fifo->rxsz, 0x0ff00004);*/
407
408 sicr = 0x01000000 | /* SIM = 0001 -- 8 bit */
409 0x00800000 | /* GenClk = 1 -- internal clk */
410 0x00008000 | /* SPI = 1 */
411 0x00004000 | /* MSTR = 1 -- SPI master */
412 0x00000800; /* UseEOF = 1 -- SS low until EOF */
413
414 out_be32(psc_addr(mps, sicr), sicr);
415
416 ccr = in_be32(psc_addr(mps, ccr));
417 ccr &= 0xFF000000;
418 speed = 1000000; /* default 1MHz */
419 bclkdiv = (mps->mclk_rate / speed) - 1;
420 ccr |= (((bclkdiv & 0xff) << 16) | (((bclkdiv >> 8) & 0xff) << 8));
421 out_be32(psc_addr(mps, ccr), ccr);
422
423 /* Set 2ms DTL delay */
424 out_8(psc_addr(mps, ctur), 0x00);
425 out_8(psc_addr(mps, ctlr), 0x82);
426
427 /* we don't use the alarms */
428 out_be32(&fifo->rxalarm, 0xfff);
429 out_be32(&fifo->txalarm, 0);
430
431 /* Enable FIFO slices for Rx/Tx */
432 out_be32(&fifo->rxcmd,
433 MPC512x_PSC_FIFO_ENABLE_SLICE | MPC512x_PSC_FIFO_ENABLE_DMA);
434 out_be32(&fifo->txcmd,
435 MPC512x_PSC_FIFO_ENABLE_SLICE | MPC512x_PSC_FIFO_ENABLE_DMA);
436
437 mps->bits_per_word = 8;
438
439 return 0;
440 }
441
mpc512x_psc_spi_isr(int irq,void * dev_id)442 static irqreturn_t mpc512x_psc_spi_isr(int irq, void *dev_id)
443 {
444 struct mpc512x_psc_spi *mps = (struct mpc512x_psc_spi *)dev_id;
445 struct mpc512x_psc_fifo __iomem *fifo = mps->fifo;
446
447 /* clear interrupt and wake up the rx/tx routine */
448 if (in_be32(&fifo->txisr) &
449 in_be32(&fifo->tximr) & MPC512x_PSC_FIFO_EMPTY) {
450 out_be32(&fifo->txisr, MPC512x_PSC_FIFO_EMPTY);
451 out_be32(&fifo->tximr, 0);
452 complete(&mps->txisrdone);
453 return IRQ_HANDLED;
454 }
455 return IRQ_NONE;
456 }
457
mpc512x_psc_spi_of_probe(struct platform_device * pdev)458 static int mpc512x_psc_spi_of_probe(struct platform_device *pdev)
459 {
460 struct device *dev = &pdev->dev;
461 struct mpc512x_psc_spi *mps;
462 struct spi_master *master;
463 int ret;
464 void *tempp;
465 struct clk *clk;
466
467 master = devm_spi_alloc_master(dev, sizeof(*mps));
468 if (master == NULL)
469 return -ENOMEM;
470
471 dev_set_drvdata(dev, master);
472 mps = spi_master_get_devdata(master);
473 mps->type = (int)device_get_match_data(dev);
474
475 master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH | SPI_LSB_FIRST;
476 master->setup = mpc512x_psc_spi_setup;
477 master->prepare_transfer_hardware = mpc512x_psc_spi_prep_xfer_hw;
478 master->transfer_one_message = mpc512x_psc_spi_msg_xfer;
479 master->unprepare_transfer_hardware = mpc512x_psc_spi_unprep_xfer_hw;
480 master->use_gpio_descriptors = true;
481 master->cleanup = mpc512x_psc_spi_cleanup;
482
483 device_set_node(&master->dev, dev_fwnode(dev));
484
485 tempp = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
486 if (IS_ERR(tempp))
487 return dev_err_probe(dev, PTR_ERR(tempp), "could not ioremap I/O port range\n");
488 mps->psc = tempp;
489 mps->fifo =
490 (struct mpc512x_psc_fifo *)(tempp + sizeof(struct mpc52xx_psc));
491
492 mps->irq = platform_get_irq(pdev, 0);
493 if (mps->irq < 0)
494 return mps->irq;
495
496 ret = devm_request_irq(dev, mps->irq, mpc512x_psc_spi_isr, IRQF_SHARED,
497 "mpc512x-psc-spi", mps);
498 if (ret)
499 return ret;
500 init_completion(&mps->txisrdone);
501
502 clk = devm_clk_get_enabled(dev, "mclk");
503 if (IS_ERR(clk))
504 return PTR_ERR(clk);
505
506 mps->mclk_rate = clk_get_rate(clk);
507
508 clk = devm_clk_get_enabled(dev, "ipg");
509 if (IS_ERR(clk))
510 return PTR_ERR(clk);
511
512 ret = mpc512x_psc_spi_port_config(master, mps);
513 if (ret < 0)
514 return ret;
515
516 return devm_spi_register_master(dev, master);
517 }
518
519 static const struct of_device_id mpc512x_psc_spi_of_match[] = {
520 { .compatible = "fsl,mpc5121-psc-spi", .data = (void *)TYPE_MPC5121 },
521 { .compatible = "fsl,mpc5125-psc-spi", .data = (void *)TYPE_MPC5125 },
522 {},
523 };
524
525 MODULE_DEVICE_TABLE(of, mpc512x_psc_spi_of_match);
526
527 static struct platform_driver mpc512x_psc_spi_of_driver = {
528 .probe = mpc512x_psc_spi_of_probe,
529 .driver = {
530 .name = "mpc512x-psc-spi",
531 .of_match_table = mpc512x_psc_spi_of_match,
532 },
533 };
534 module_platform_driver(mpc512x_psc_spi_of_driver);
535
536 MODULE_AUTHOR("John Rigby");
537 MODULE_DESCRIPTION("MPC512x PSC SPI Driver");
538 MODULE_LICENSE("GPL");
539