1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * MPC52xx SPI bus driver.
4 *
5 * Copyright (C) 2008 Secret Lab Technologies Ltd.
6 *
7 * This is the driver for the MPC5200's dedicated SPI controller.
8 *
9 * Note: this driver does not support the MPC5200 PSC in SPI mode. For
10 * that driver see drivers/spi/mpc52xx_psc_spi.c
11 */
12
13 #include <linux/module.h>
14 #include <linux/err.h>
15 #include <linux/errno.h>
16 #include <linux/of_platform.h>
17 #include <linux/interrupt.h>
18 #include <linux/delay.h>
19 #include <linux/gpio/consumer.h>
20 #include <linux/spi/spi.h>
21 #include <linux/io.h>
22 #include <linux/slab.h>
23 #include <linux/of_address.h>
24 #include <linux/of_irq.h>
25
26 #include <asm/time.h>
27 #include <asm/mpc52xx.h>
28
29 MODULE_AUTHOR("Grant Likely <grant.likely@secretlab.ca>");
30 MODULE_DESCRIPTION("MPC52xx SPI (non-PSC) Driver");
31 MODULE_LICENSE("GPL");
32
33 /* Register offsets */
34 #define SPI_CTRL1 0x00
35 #define SPI_CTRL1_SPIE (1 << 7)
36 #define SPI_CTRL1_SPE (1 << 6)
37 #define SPI_CTRL1_MSTR (1 << 4)
38 #define SPI_CTRL1_CPOL (1 << 3)
39 #define SPI_CTRL1_CPHA (1 << 2)
40 #define SPI_CTRL1_SSOE (1 << 1)
41 #define SPI_CTRL1_LSBFE (1 << 0)
42
43 #define SPI_CTRL2 0x01
44 #define SPI_BRR 0x04
45
46 #define SPI_STATUS 0x05
47 #define SPI_STATUS_SPIF (1 << 7)
48 #define SPI_STATUS_WCOL (1 << 6)
49 #define SPI_STATUS_MODF (1 << 4)
50
51 #define SPI_DATA 0x09
52 #define SPI_PORTDATA 0x0d
53 #define SPI_DATADIR 0x10
54
55 /* FSM state return values */
56 #define FSM_STOP 0 /* Nothing more for the state machine to */
57 /* do. If something interesting happens */
58 /* then an IRQ will be received */
59 #define FSM_POLL 1 /* need to poll for completion, an IRQ is */
60 /* not expected */
61 #define FSM_CONTINUE 2 /* Keep iterating the state machine */
62
63 /* Driver internal data */
64 struct mpc52xx_spi {
65 struct spi_master *master;
66 void __iomem *regs;
67 int irq0; /* MODF irq */
68 int irq1; /* SPIF irq */
69 unsigned int ipb_freq;
70
71 /* Statistics; not used now, but will be reintroduced for debugfs */
72 int msg_count;
73 int wcol_count;
74 int wcol_ticks;
75 u32 wcol_tx_timestamp;
76 int modf_count;
77 int byte_count;
78
79 struct list_head queue; /* queue of pending messages */
80 spinlock_t lock;
81 struct work_struct work;
82
83 /* Details of current transfer (length, and buffer pointers) */
84 struct spi_message *message; /* current message */
85 struct spi_transfer *transfer; /* current transfer */
86 int (*state)(int irq, struct mpc52xx_spi *ms, u8 status, u8 data);
87 int len;
88 int timestamp;
89 u8 *rx_buf;
90 const u8 *tx_buf;
91 int cs_change;
92 int gpio_cs_count;
93 struct gpio_desc **gpio_cs;
94 };
95
96 /*
97 * CS control function
98 */
mpc52xx_spi_chipsel(struct mpc52xx_spi * ms,int value)99 static void mpc52xx_spi_chipsel(struct mpc52xx_spi *ms, int value)
100 {
101 int cs;
102
103 if (ms->gpio_cs_count > 0) {
104 cs = spi_get_chipselect(ms->message->spi, 0);
105 gpiod_set_value(ms->gpio_cs[cs], value);
106 } else {
107 out_8(ms->regs + SPI_PORTDATA, value ? 0 : 0x08);
108 }
109 }
110
111 /*
112 * Start a new transfer. This is called both by the idle state
113 * for the first transfer in a message, and by the wait state when the
114 * previous transfer in a message is complete.
115 */
mpc52xx_spi_start_transfer(struct mpc52xx_spi * ms)116 static void mpc52xx_spi_start_transfer(struct mpc52xx_spi *ms)
117 {
118 ms->rx_buf = ms->transfer->rx_buf;
119 ms->tx_buf = ms->transfer->tx_buf;
120 ms->len = ms->transfer->len;
121
122 /* Activate the chip select */
123 if (ms->cs_change)
124 mpc52xx_spi_chipsel(ms, 1);
125 ms->cs_change = ms->transfer->cs_change;
126
127 /* Write out the first byte */
128 ms->wcol_tx_timestamp = mftb();
129 if (ms->tx_buf)
130 out_8(ms->regs + SPI_DATA, *ms->tx_buf++);
131 else
132 out_8(ms->regs + SPI_DATA, 0);
133 }
134
135 /* Forward declaration of state handlers */
136 static int mpc52xx_spi_fsmstate_transfer(int irq, struct mpc52xx_spi *ms,
137 u8 status, u8 data);
138 static int mpc52xx_spi_fsmstate_wait(int irq, struct mpc52xx_spi *ms,
139 u8 status, u8 data);
140
141 /*
142 * IDLE state
143 *
144 * No transfers are in progress; if another transfer is pending then retrieve
145 * it and kick it off. Otherwise, stop processing the state machine
146 */
147 static int
mpc52xx_spi_fsmstate_idle(int irq,struct mpc52xx_spi * ms,u8 status,u8 data)148 mpc52xx_spi_fsmstate_idle(int irq, struct mpc52xx_spi *ms, u8 status, u8 data)
149 {
150 struct spi_device *spi;
151 int spr, sppr;
152 u8 ctrl1;
153
154 if (status && irq)
155 dev_err(&ms->master->dev, "spurious irq, status=0x%.2x\n",
156 status);
157
158 /* Check if there is another transfer waiting. */
159 if (list_empty(&ms->queue))
160 return FSM_STOP;
161
162 /* get the head of the queue */
163 ms->message = list_first_entry(&ms->queue, struct spi_message, queue);
164 list_del_init(&ms->message->queue);
165
166 /* Setup the controller parameters */
167 ctrl1 = SPI_CTRL1_SPIE | SPI_CTRL1_SPE | SPI_CTRL1_MSTR;
168 spi = ms->message->spi;
169 if (spi->mode & SPI_CPHA)
170 ctrl1 |= SPI_CTRL1_CPHA;
171 if (spi->mode & SPI_CPOL)
172 ctrl1 |= SPI_CTRL1_CPOL;
173 if (spi->mode & SPI_LSB_FIRST)
174 ctrl1 |= SPI_CTRL1_LSBFE;
175 out_8(ms->regs + SPI_CTRL1, ctrl1);
176
177 /* Setup the controller speed */
178 /* minimum divider is '2'. Also, add '1' to force rounding the
179 * divider up. */
180 sppr = ((ms->ipb_freq / ms->message->spi->max_speed_hz) + 1) >> 1;
181 spr = 0;
182 if (sppr < 1)
183 sppr = 1;
184 while (((sppr - 1) & ~0x7) != 0) {
185 sppr = (sppr + 1) >> 1; /* add '1' to force rounding up */
186 spr++;
187 }
188 sppr--; /* sppr quantity in register is offset by 1 */
189 if (spr > 7) {
190 /* Don't overrun limits of SPI baudrate register */
191 spr = 7;
192 sppr = 7;
193 }
194 out_8(ms->regs + SPI_BRR, sppr << 4 | spr); /* Set speed */
195
196 ms->cs_change = 1;
197 ms->transfer = container_of(ms->message->transfers.next,
198 struct spi_transfer, transfer_list);
199
200 mpc52xx_spi_start_transfer(ms);
201 ms->state = mpc52xx_spi_fsmstate_transfer;
202
203 return FSM_CONTINUE;
204 }
205
206 /*
207 * TRANSFER state
208 *
209 * In the middle of a transfer. If the SPI core has completed processing
210 * a byte, then read out the received data and write out the next byte
211 * (unless this transfer is finished; in which case go on to the wait
212 * state)
213 */
mpc52xx_spi_fsmstate_transfer(int irq,struct mpc52xx_spi * ms,u8 status,u8 data)214 static int mpc52xx_spi_fsmstate_transfer(int irq, struct mpc52xx_spi *ms,
215 u8 status, u8 data)
216 {
217 if (!status)
218 return ms->irq0 ? FSM_STOP : FSM_POLL;
219
220 if (status & SPI_STATUS_WCOL) {
221 /* The SPI controller is stoopid. At slower speeds, it may
222 * raise the SPIF flag before the state machine is actually
223 * finished, which causes a collision (internal to the state
224 * machine only). The manual recommends inserting a delay
225 * between receiving the interrupt and sending the next byte,
226 * but it can also be worked around simply by retrying the
227 * transfer which is what we do here. */
228 ms->wcol_count++;
229 ms->wcol_ticks += mftb() - ms->wcol_tx_timestamp;
230 ms->wcol_tx_timestamp = mftb();
231 data = 0;
232 if (ms->tx_buf)
233 data = *(ms->tx_buf - 1);
234 out_8(ms->regs + SPI_DATA, data); /* try again */
235 return FSM_CONTINUE;
236 } else if (status & SPI_STATUS_MODF) {
237 ms->modf_count++;
238 dev_err(&ms->master->dev, "mode fault\n");
239 mpc52xx_spi_chipsel(ms, 0);
240 ms->message->status = -EIO;
241 if (ms->message->complete)
242 ms->message->complete(ms->message->context);
243 ms->state = mpc52xx_spi_fsmstate_idle;
244 return FSM_CONTINUE;
245 }
246
247 /* Read data out of the spi device */
248 ms->byte_count++;
249 if (ms->rx_buf)
250 *ms->rx_buf++ = data;
251
252 /* Is the transfer complete? */
253 ms->len--;
254 if (ms->len == 0) {
255 ms->timestamp = mftb();
256 if (ms->transfer->delay.unit == SPI_DELAY_UNIT_USECS)
257 ms->timestamp += ms->transfer->delay.value *
258 tb_ticks_per_usec;
259 ms->state = mpc52xx_spi_fsmstate_wait;
260 return FSM_CONTINUE;
261 }
262
263 /* Write out the next byte */
264 ms->wcol_tx_timestamp = mftb();
265 if (ms->tx_buf)
266 out_8(ms->regs + SPI_DATA, *ms->tx_buf++);
267 else
268 out_8(ms->regs + SPI_DATA, 0);
269
270 return FSM_CONTINUE;
271 }
272
273 /*
274 * WAIT state
275 *
276 * A transfer has completed; need to wait for the delay period to complete
277 * before starting the next transfer
278 */
279 static int
mpc52xx_spi_fsmstate_wait(int irq,struct mpc52xx_spi * ms,u8 status,u8 data)280 mpc52xx_spi_fsmstate_wait(int irq, struct mpc52xx_spi *ms, u8 status, u8 data)
281 {
282 if (status && irq)
283 dev_err(&ms->master->dev, "spurious irq, status=0x%.2x\n",
284 status);
285
286 if (((int)mftb()) - ms->timestamp < 0)
287 return FSM_POLL;
288
289 ms->message->actual_length += ms->transfer->len;
290
291 /* Check if there is another transfer in this message. If there
292 * aren't then deactivate CS, notify sender, and drop back to idle
293 * to start the next message. */
294 if (ms->transfer->transfer_list.next == &ms->message->transfers) {
295 ms->msg_count++;
296 mpc52xx_spi_chipsel(ms, 0);
297 ms->message->status = 0;
298 if (ms->message->complete)
299 ms->message->complete(ms->message->context);
300 ms->state = mpc52xx_spi_fsmstate_idle;
301 return FSM_CONTINUE;
302 }
303
304 /* There is another transfer; kick it off */
305
306 if (ms->cs_change)
307 mpc52xx_spi_chipsel(ms, 0);
308
309 ms->transfer = container_of(ms->transfer->transfer_list.next,
310 struct spi_transfer, transfer_list);
311 mpc52xx_spi_start_transfer(ms);
312 ms->state = mpc52xx_spi_fsmstate_transfer;
313 return FSM_CONTINUE;
314 }
315
316 /**
317 * mpc52xx_spi_fsm_process - Finite State Machine iteration function
318 * @irq: irq number that triggered the FSM or 0 for polling
319 * @ms: pointer to mpc52xx_spi driver data
320 */
mpc52xx_spi_fsm_process(int irq,struct mpc52xx_spi * ms)321 static void mpc52xx_spi_fsm_process(int irq, struct mpc52xx_spi *ms)
322 {
323 int rc = FSM_CONTINUE;
324 u8 status, data;
325
326 while (rc == FSM_CONTINUE) {
327 /* Interrupt cleared by read of STATUS followed by
328 * read of DATA registers */
329 status = in_8(ms->regs + SPI_STATUS);
330 data = in_8(ms->regs + SPI_DATA);
331 rc = ms->state(irq, ms, status, data);
332 }
333
334 if (rc == FSM_POLL)
335 schedule_work(&ms->work);
336 }
337
338 /**
339 * mpc52xx_spi_irq - IRQ handler
340 */
mpc52xx_spi_irq(int irq,void * _ms)341 static irqreturn_t mpc52xx_spi_irq(int irq, void *_ms)
342 {
343 struct mpc52xx_spi *ms = _ms;
344 spin_lock(&ms->lock);
345 mpc52xx_spi_fsm_process(irq, ms);
346 spin_unlock(&ms->lock);
347 return IRQ_HANDLED;
348 }
349
350 /**
351 * mpc52xx_spi_wq - Workqueue function for polling the state machine
352 */
mpc52xx_spi_wq(struct work_struct * work)353 static void mpc52xx_spi_wq(struct work_struct *work)
354 {
355 struct mpc52xx_spi *ms = container_of(work, struct mpc52xx_spi, work);
356 unsigned long flags;
357
358 spin_lock_irqsave(&ms->lock, flags);
359 mpc52xx_spi_fsm_process(0, ms);
360 spin_unlock_irqrestore(&ms->lock, flags);
361 }
362
363 /*
364 * spi_master ops
365 */
366
mpc52xx_spi_transfer(struct spi_device * spi,struct spi_message * m)367 static int mpc52xx_spi_transfer(struct spi_device *spi, struct spi_message *m)
368 {
369 struct mpc52xx_spi *ms = spi_master_get_devdata(spi->master);
370 unsigned long flags;
371
372 m->actual_length = 0;
373 m->status = -EINPROGRESS;
374
375 spin_lock_irqsave(&ms->lock, flags);
376 list_add_tail(&m->queue, &ms->queue);
377 spin_unlock_irqrestore(&ms->lock, flags);
378 schedule_work(&ms->work);
379
380 return 0;
381 }
382
383 /*
384 * OF Platform Bus Binding
385 */
mpc52xx_spi_probe(struct platform_device * op)386 static int mpc52xx_spi_probe(struct platform_device *op)
387 {
388 struct spi_master *master;
389 struct mpc52xx_spi *ms;
390 struct gpio_desc *gpio_cs;
391 void __iomem *regs;
392 u8 ctrl1;
393 int rc, i = 0;
394
395 /* MMIO registers */
396 dev_dbg(&op->dev, "probing mpc5200 SPI device\n");
397 regs = of_iomap(op->dev.of_node, 0);
398 if (!regs)
399 return -ENODEV;
400
401 /* initialize the device */
402 ctrl1 = SPI_CTRL1_SPIE | SPI_CTRL1_SPE | SPI_CTRL1_MSTR;
403 out_8(regs + SPI_CTRL1, ctrl1);
404 out_8(regs + SPI_CTRL2, 0x0);
405 out_8(regs + SPI_DATADIR, 0xe); /* Set output pins */
406 out_8(regs + SPI_PORTDATA, 0x8); /* Deassert /SS signal */
407
408 /* Clear the status register and re-read it to check for a MODF
409 * failure. This driver cannot currently handle multiple masters
410 * on the SPI bus. This fault will also occur if the SPI signals
411 * are not connected to any pins (port_config setting) */
412 in_8(regs + SPI_STATUS);
413 out_8(regs + SPI_CTRL1, ctrl1);
414
415 in_8(regs + SPI_DATA);
416 if (in_8(regs + SPI_STATUS) & SPI_STATUS_MODF) {
417 dev_err(&op->dev, "mode fault; is port_config correct?\n");
418 rc = -EIO;
419 goto err_init;
420 }
421
422 dev_dbg(&op->dev, "allocating spi_master struct\n");
423 master = spi_alloc_master(&op->dev, sizeof(*ms));
424 if (!master) {
425 rc = -ENOMEM;
426 goto err_alloc;
427 }
428
429 master->transfer = mpc52xx_spi_transfer;
430 master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_LSB_FIRST;
431 master->bits_per_word_mask = SPI_BPW_MASK(8);
432 master->dev.of_node = op->dev.of_node;
433
434 platform_set_drvdata(op, master);
435
436 ms = spi_master_get_devdata(master);
437 ms->master = master;
438 ms->regs = regs;
439 ms->irq0 = irq_of_parse_and_map(op->dev.of_node, 0);
440 ms->irq1 = irq_of_parse_and_map(op->dev.of_node, 1);
441 ms->state = mpc52xx_spi_fsmstate_idle;
442 ms->ipb_freq = mpc5xxx_get_bus_frequency(&op->dev);
443 ms->gpio_cs_count = gpiod_count(&op->dev, NULL);
444 if (ms->gpio_cs_count > 0) {
445 master->num_chipselect = ms->gpio_cs_count;
446 ms->gpio_cs = kmalloc_array(ms->gpio_cs_count,
447 sizeof(*ms->gpio_cs),
448 GFP_KERNEL);
449 if (!ms->gpio_cs) {
450 rc = -ENOMEM;
451 goto err_alloc_gpio;
452 }
453
454 for (i = 0; i < ms->gpio_cs_count; i++) {
455 gpio_cs = gpiod_get_index(&op->dev,
456 NULL, i, GPIOD_OUT_LOW);
457 rc = PTR_ERR_OR_ZERO(gpio_cs);
458 if (rc) {
459 dev_err(&op->dev,
460 "failed to get spi cs gpio #%d: %d\n",
461 i, rc);
462 goto err_gpio;
463 }
464
465 ms->gpio_cs[i] = gpio_cs;
466 }
467 }
468
469 spin_lock_init(&ms->lock);
470 INIT_LIST_HEAD(&ms->queue);
471 INIT_WORK(&ms->work, mpc52xx_spi_wq);
472
473 /* Decide if interrupts can be used */
474 if (ms->irq0 && ms->irq1) {
475 rc = request_irq(ms->irq0, mpc52xx_spi_irq, 0,
476 "mpc5200-spi-modf", ms);
477 rc |= request_irq(ms->irq1, mpc52xx_spi_irq, 0,
478 "mpc5200-spi-spif", ms);
479 if (rc) {
480 free_irq(ms->irq0, ms);
481 free_irq(ms->irq1, ms);
482 ms->irq0 = ms->irq1 = 0;
483 }
484 } else {
485 /* operate in polled mode */
486 ms->irq0 = ms->irq1 = 0;
487 }
488
489 if (!ms->irq0)
490 dev_info(&op->dev, "using polled mode\n");
491
492 dev_dbg(&op->dev, "registering spi_master struct\n");
493 rc = spi_register_master(master);
494 if (rc)
495 goto err_register;
496
497 dev_info(&ms->master->dev, "registered MPC5200 SPI bus\n");
498
499 return rc;
500
501 err_register:
502 dev_err(&ms->master->dev, "initialization failed\n");
503 err_gpio:
504 while (i-- > 0)
505 gpiod_put(ms->gpio_cs[i]);
506
507 kfree(ms->gpio_cs);
508 err_alloc_gpio:
509 spi_master_put(master);
510 err_alloc:
511 err_init:
512 iounmap(regs);
513 return rc;
514 }
515
mpc52xx_spi_remove(struct platform_device * op)516 static void mpc52xx_spi_remove(struct platform_device *op)
517 {
518 struct spi_master *master = spi_master_get(platform_get_drvdata(op));
519 struct mpc52xx_spi *ms = spi_master_get_devdata(master);
520 int i;
521
522 free_irq(ms->irq0, ms);
523 free_irq(ms->irq1, ms);
524
525 for (i = 0; i < ms->gpio_cs_count; i++)
526 gpiod_put(ms->gpio_cs[i]);
527
528 kfree(ms->gpio_cs);
529 spi_unregister_master(master);
530 iounmap(ms->regs);
531 spi_master_put(master);
532 }
533
534 static const struct of_device_id mpc52xx_spi_match[] = {
535 { .compatible = "fsl,mpc5200-spi", },
536 {}
537 };
538 MODULE_DEVICE_TABLE(of, mpc52xx_spi_match);
539
540 static struct platform_driver mpc52xx_spi_of_driver = {
541 .driver = {
542 .name = "mpc52xx-spi",
543 .of_match_table = mpc52xx_spi_match,
544 },
545 .probe = mpc52xx_spi_probe,
546 .remove_new = mpc52xx_spi_remove,
547 };
548 module_platform_driver(mpc52xx_spi_of_driver);
549