1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Tegra20 External Memory Controller driver
4  *
5  * Author: Dmitry Osipenko <digetx@gmail.com>
6  */
7 
8 #include <linux/clk.h>
9 #include <linux/clk/tegra.h>
10 #include <linux/completion.h>
11 #include <linux/debugfs.h>
12 #include <linux/err.h>
13 #include <linux/interrupt.h>
14 #include <linux/io.h>
15 #include <linux/kernel.h>
16 #include <linux/module.h>
17 #include <linux/of.h>
18 #include <linux/platform_device.h>
19 #include <linux/sort.h>
20 #include <linux/types.h>
21 
22 #include <soc/tegra/fuse.h>
23 
24 #define EMC_INTSTATUS				0x000
25 #define EMC_INTMASK				0x004
26 #define EMC_DBG					0x008
27 #define EMC_TIMING_CONTROL			0x028
28 #define EMC_RC					0x02c
29 #define EMC_RFC					0x030
30 #define EMC_RAS					0x034
31 #define EMC_RP					0x038
32 #define EMC_R2W					0x03c
33 #define EMC_W2R					0x040
34 #define EMC_R2P					0x044
35 #define EMC_W2P					0x048
36 #define EMC_RD_RCD				0x04c
37 #define EMC_WR_RCD				0x050
38 #define EMC_RRD					0x054
39 #define EMC_REXT				0x058
40 #define EMC_WDV					0x05c
41 #define EMC_QUSE				0x060
42 #define EMC_QRST				0x064
43 #define EMC_QSAFE				0x068
44 #define EMC_RDV					0x06c
45 #define EMC_REFRESH				0x070
46 #define EMC_BURST_REFRESH_NUM			0x074
47 #define EMC_PDEX2WR				0x078
48 #define EMC_PDEX2RD				0x07c
49 #define EMC_PCHG2PDEN				0x080
50 #define EMC_ACT2PDEN				0x084
51 #define EMC_AR2PDEN				0x088
52 #define EMC_RW2PDEN				0x08c
53 #define EMC_TXSR				0x090
54 #define EMC_TCKE				0x094
55 #define EMC_TFAW				0x098
56 #define EMC_TRPAB				0x09c
57 #define EMC_TCLKSTABLE				0x0a0
58 #define EMC_TCLKSTOP				0x0a4
59 #define EMC_TREFBW				0x0a8
60 #define EMC_QUSE_EXTRA				0x0ac
61 #define EMC_ODT_WRITE				0x0b0
62 #define EMC_ODT_READ				0x0b4
63 #define EMC_FBIO_CFG5				0x104
64 #define EMC_FBIO_CFG6				0x114
65 #define EMC_AUTO_CAL_INTERVAL			0x2a8
66 #define EMC_CFG_2				0x2b8
67 #define EMC_CFG_DIG_DLL				0x2bc
68 #define EMC_DLL_XFORM_DQS			0x2c0
69 #define EMC_DLL_XFORM_QUSE			0x2c4
70 #define EMC_ZCAL_REF_CNT			0x2e0
71 #define EMC_ZCAL_WAIT_CNT			0x2e4
72 #define EMC_CFG_CLKTRIM_0			0x2d0
73 #define EMC_CFG_CLKTRIM_1			0x2d4
74 #define EMC_CFG_CLKTRIM_2			0x2d8
75 
76 #define EMC_CLKCHANGE_REQ_ENABLE		BIT(0)
77 #define EMC_CLKCHANGE_PD_ENABLE			BIT(1)
78 #define EMC_CLKCHANGE_SR_ENABLE			BIT(2)
79 
80 #define EMC_TIMING_UPDATE			BIT(0)
81 
82 #define EMC_REFRESH_OVERFLOW_INT		BIT(3)
83 #define EMC_CLKCHANGE_COMPLETE_INT		BIT(4)
84 
85 #define EMC_DBG_READ_MUX_ASSEMBLY		BIT(0)
86 #define EMC_DBG_WRITE_MUX_ACTIVE		BIT(1)
87 #define EMC_DBG_FORCE_UPDATE			BIT(2)
88 #define EMC_DBG_READ_DQM_CTRL			BIT(9)
89 #define EMC_DBG_CFG_PRIORITY			BIT(24)
90 
91 static const u16 emc_timing_registers[] = {
92 	EMC_RC,
93 	EMC_RFC,
94 	EMC_RAS,
95 	EMC_RP,
96 	EMC_R2W,
97 	EMC_W2R,
98 	EMC_R2P,
99 	EMC_W2P,
100 	EMC_RD_RCD,
101 	EMC_WR_RCD,
102 	EMC_RRD,
103 	EMC_REXT,
104 	EMC_WDV,
105 	EMC_QUSE,
106 	EMC_QRST,
107 	EMC_QSAFE,
108 	EMC_RDV,
109 	EMC_REFRESH,
110 	EMC_BURST_REFRESH_NUM,
111 	EMC_PDEX2WR,
112 	EMC_PDEX2RD,
113 	EMC_PCHG2PDEN,
114 	EMC_ACT2PDEN,
115 	EMC_AR2PDEN,
116 	EMC_RW2PDEN,
117 	EMC_TXSR,
118 	EMC_TCKE,
119 	EMC_TFAW,
120 	EMC_TRPAB,
121 	EMC_TCLKSTABLE,
122 	EMC_TCLKSTOP,
123 	EMC_TREFBW,
124 	EMC_QUSE_EXTRA,
125 	EMC_FBIO_CFG6,
126 	EMC_ODT_WRITE,
127 	EMC_ODT_READ,
128 	EMC_FBIO_CFG5,
129 	EMC_CFG_DIG_DLL,
130 	EMC_DLL_XFORM_DQS,
131 	EMC_DLL_XFORM_QUSE,
132 	EMC_ZCAL_REF_CNT,
133 	EMC_ZCAL_WAIT_CNT,
134 	EMC_AUTO_CAL_INTERVAL,
135 	EMC_CFG_CLKTRIM_0,
136 	EMC_CFG_CLKTRIM_1,
137 	EMC_CFG_CLKTRIM_2,
138 };
139 
140 struct emc_timing {
141 	unsigned long rate;
142 	u32 data[ARRAY_SIZE(emc_timing_registers)];
143 };
144 
145 struct tegra_emc {
146 	struct device *dev;
147 	struct completion clk_handshake_complete;
148 	struct notifier_block clk_nb;
149 	struct clk *clk;
150 	void __iomem *regs;
151 
152 	struct emc_timing *timings;
153 	unsigned int num_timings;
154 
155 	struct {
156 		struct dentry *root;
157 		unsigned long min_rate;
158 		unsigned long max_rate;
159 	} debugfs;
160 };
161 
162 static irqreturn_t tegra_emc_isr(int irq, void *data)
163 {
164 	struct tegra_emc *emc = data;
165 	u32 intmask = EMC_REFRESH_OVERFLOW_INT | EMC_CLKCHANGE_COMPLETE_INT;
166 	u32 status;
167 
168 	status = readl_relaxed(emc->regs + EMC_INTSTATUS) & intmask;
169 	if (!status)
170 		return IRQ_NONE;
171 
172 	/* notify about EMC-CAR handshake completion */
173 	if (status & EMC_CLKCHANGE_COMPLETE_INT)
174 		complete(&emc->clk_handshake_complete);
175 
176 	/* notify about HW problem */
177 	if (status & EMC_REFRESH_OVERFLOW_INT)
178 		dev_err_ratelimited(emc->dev,
179 				    "refresh request overflow timeout\n");
180 
181 	/* clear interrupts */
182 	writel_relaxed(status, emc->regs + EMC_INTSTATUS);
183 
184 	return IRQ_HANDLED;
185 }
186 
187 static struct emc_timing *tegra_emc_find_timing(struct tegra_emc *emc,
188 						unsigned long rate)
189 {
190 	struct emc_timing *timing = NULL;
191 	unsigned int i;
192 
193 	for (i = 0; i < emc->num_timings; i++) {
194 		if (emc->timings[i].rate >= rate) {
195 			timing = &emc->timings[i];
196 			break;
197 		}
198 	}
199 
200 	if (!timing) {
201 		dev_err(emc->dev, "no timing for rate %lu\n", rate);
202 		return NULL;
203 	}
204 
205 	return timing;
206 }
207 
208 static int emc_prepare_timing_change(struct tegra_emc *emc, unsigned long rate)
209 {
210 	struct emc_timing *timing = tegra_emc_find_timing(emc, rate);
211 	unsigned int i;
212 
213 	if (!timing)
214 		return -EINVAL;
215 
216 	dev_dbg(emc->dev, "%s: using timing rate %lu for requested rate %lu\n",
217 		__func__, timing->rate, rate);
218 
219 	/* program shadow registers */
220 	for (i = 0; i < ARRAY_SIZE(timing->data); i++)
221 		writel_relaxed(timing->data[i],
222 			       emc->regs + emc_timing_registers[i]);
223 
224 	/* wait until programming has settled */
225 	readl_relaxed(emc->regs + emc_timing_registers[i - 1]);
226 
227 	reinit_completion(&emc->clk_handshake_complete);
228 
229 	return 0;
230 }
231 
232 static int emc_complete_timing_change(struct tegra_emc *emc, bool flush)
233 {
234 	unsigned long timeout;
235 
236 	dev_dbg(emc->dev, "%s: flush %d\n", __func__, flush);
237 
238 	if (flush) {
239 		/* manually initiate memory timing update */
240 		writel_relaxed(EMC_TIMING_UPDATE,
241 			       emc->regs + EMC_TIMING_CONTROL);
242 		return 0;
243 	}
244 
245 	timeout = wait_for_completion_timeout(&emc->clk_handshake_complete,
246 					      msecs_to_jiffies(100));
247 	if (timeout == 0) {
248 		dev_err(emc->dev, "EMC-CAR handshake failed\n");
249 		return -EIO;
250 	}
251 
252 	return 0;
253 }
254 
255 static int tegra_emc_clk_change_notify(struct notifier_block *nb,
256 				       unsigned long msg, void *data)
257 {
258 	struct tegra_emc *emc = container_of(nb, struct tegra_emc, clk_nb);
259 	struct clk_notifier_data *cnd = data;
260 	int err;
261 
262 	switch (msg) {
263 	case PRE_RATE_CHANGE:
264 		err = emc_prepare_timing_change(emc, cnd->new_rate);
265 		break;
266 
267 	case ABORT_RATE_CHANGE:
268 		err = emc_prepare_timing_change(emc, cnd->old_rate);
269 		if (err)
270 			break;
271 
272 		err = emc_complete_timing_change(emc, true);
273 		break;
274 
275 	case POST_RATE_CHANGE:
276 		err = emc_complete_timing_change(emc, false);
277 		break;
278 
279 	default:
280 		return NOTIFY_DONE;
281 	}
282 
283 	return notifier_from_errno(err);
284 }
285 
286 static int load_one_timing_from_dt(struct tegra_emc *emc,
287 				   struct emc_timing *timing,
288 				   struct device_node *node)
289 {
290 	u32 rate;
291 	int err;
292 
293 	if (!of_device_is_compatible(node, "nvidia,tegra20-emc-table")) {
294 		dev_err(emc->dev, "incompatible DT node: %pOF\n", node);
295 		return -EINVAL;
296 	}
297 
298 	err = of_property_read_u32(node, "clock-frequency", &rate);
299 	if (err) {
300 		dev_err(emc->dev, "timing %pOF: failed to read rate: %d\n",
301 			node, err);
302 		return err;
303 	}
304 
305 	err = of_property_read_u32_array(node, "nvidia,emc-registers",
306 					 timing->data,
307 					 ARRAY_SIZE(emc_timing_registers));
308 	if (err) {
309 		dev_err(emc->dev,
310 			"timing %pOF: failed to read emc timing data: %d\n",
311 			node, err);
312 		return err;
313 	}
314 
315 	/*
316 	 * The EMC clock rate is twice the bus rate, and the bus rate is
317 	 * measured in kHz.
318 	 */
319 	timing->rate = rate * 2 * 1000;
320 
321 	dev_dbg(emc->dev, "%s: %pOF: EMC rate %lu\n",
322 		__func__, node, timing->rate);
323 
324 	return 0;
325 }
326 
327 static int cmp_timings(const void *_a, const void *_b)
328 {
329 	const struct emc_timing *a = _a;
330 	const struct emc_timing *b = _b;
331 
332 	if (a->rate < b->rate)
333 		return -1;
334 
335 	if (a->rate > b->rate)
336 		return 1;
337 
338 	return 0;
339 }
340 
341 static int tegra_emc_load_timings_from_dt(struct tegra_emc *emc,
342 					  struct device_node *node)
343 {
344 	struct device_node *child;
345 	struct emc_timing *timing;
346 	int child_count;
347 	int err;
348 
349 	child_count = of_get_child_count(node);
350 	if (!child_count) {
351 		dev_err(emc->dev, "no memory timings in DT node: %pOF\n", node);
352 		return -EINVAL;
353 	}
354 
355 	emc->timings = devm_kcalloc(emc->dev, child_count, sizeof(*timing),
356 				    GFP_KERNEL);
357 	if (!emc->timings)
358 		return -ENOMEM;
359 
360 	emc->num_timings = child_count;
361 	timing = emc->timings;
362 
363 	for_each_child_of_node(node, child) {
364 		err = load_one_timing_from_dt(emc, timing++, child);
365 		if (err) {
366 			of_node_put(child);
367 			return err;
368 		}
369 	}
370 
371 	sort(emc->timings, emc->num_timings, sizeof(*timing), cmp_timings,
372 	     NULL);
373 
374 	dev_info(emc->dev,
375 		 "got %u timings for RAM code %u (min %luMHz max %luMHz)\n",
376 		 emc->num_timings,
377 		 tegra_read_ram_code(),
378 		 emc->timings[0].rate / 1000000,
379 		 emc->timings[emc->num_timings - 1].rate / 1000000);
380 
381 	return 0;
382 }
383 
384 static struct device_node *
385 tegra_emc_find_node_by_ram_code(struct device *dev)
386 {
387 	struct device_node *np;
388 	u32 value, ram_code;
389 	int err;
390 
391 	if (!of_property_read_bool(dev->of_node, "nvidia,use-ram-code"))
392 		return of_node_get(dev->of_node);
393 
394 	ram_code = tegra_read_ram_code();
395 
396 	for (np = of_find_node_by_name(dev->of_node, "emc-tables"); np;
397 	     np = of_find_node_by_name(np, "emc-tables")) {
398 		err = of_property_read_u32(np, "nvidia,ram-code", &value);
399 		if (err || value != ram_code) {
400 			of_node_put(np);
401 			continue;
402 		}
403 
404 		return np;
405 	}
406 
407 	dev_err(dev, "no memory timings for RAM code %u found in device tree\n",
408 		ram_code);
409 
410 	return NULL;
411 }
412 
413 static int emc_setup_hw(struct tegra_emc *emc)
414 {
415 	u32 intmask = EMC_REFRESH_OVERFLOW_INT | EMC_CLKCHANGE_COMPLETE_INT;
416 	u32 emc_cfg, emc_dbg;
417 
418 	emc_cfg = readl_relaxed(emc->regs + EMC_CFG_2);
419 
420 	/*
421 	 * Depending on a memory type, DRAM should enter either self-refresh
422 	 * or power-down state on EMC clock change.
423 	 */
424 	if (!(emc_cfg & EMC_CLKCHANGE_PD_ENABLE) &&
425 	    !(emc_cfg & EMC_CLKCHANGE_SR_ENABLE)) {
426 		dev_err(emc->dev,
427 			"bootloader didn't specify DRAM auto-suspend mode\n");
428 		return -EINVAL;
429 	}
430 
431 	/* enable EMC and CAR to handshake on PLL divider/source changes */
432 	emc_cfg |= EMC_CLKCHANGE_REQ_ENABLE;
433 	writel_relaxed(emc_cfg, emc->regs + EMC_CFG_2);
434 
435 	/* initialize interrupt */
436 	writel_relaxed(intmask, emc->regs + EMC_INTMASK);
437 	writel_relaxed(intmask, emc->regs + EMC_INTSTATUS);
438 
439 	/* ensure that unwanted debug features are disabled */
440 	emc_dbg = readl_relaxed(emc->regs + EMC_DBG);
441 	emc_dbg |= EMC_DBG_CFG_PRIORITY;
442 	emc_dbg &= ~EMC_DBG_READ_MUX_ASSEMBLY;
443 	emc_dbg &= ~EMC_DBG_WRITE_MUX_ACTIVE;
444 	emc_dbg &= ~EMC_DBG_FORCE_UPDATE;
445 	writel_relaxed(emc_dbg, emc->regs + EMC_DBG);
446 
447 	return 0;
448 }
449 
450 static long emc_round_rate(unsigned long rate,
451 			   unsigned long min_rate,
452 			   unsigned long max_rate,
453 			   void *arg)
454 {
455 	struct emc_timing *timing = NULL;
456 	struct tegra_emc *emc = arg;
457 	unsigned int i;
458 
459 	min_rate = min(min_rate, emc->timings[emc->num_timings - 1].rate);
460 
461 	for (i = 0; i < emc->num_timings; i++) {
462 		if (emc->timings[i].rate < rate && i != emc->num_timings - 1)
463 			continue;
464 
465 		if (emc->timings[i].rate > max_rate) {
466 			i = max(i, 1u) - 1;
467 
468 			if (emc->timings[i].rate < min_rate)
469 				break;
470 		}
471 
472 		if (emc->timings[i].rate < min_rate)
473 			continue;
474 
475 		timing = &emc->timings[i];
476 		break;
477 	}
478 
479 	if (!timing) {
480 		dev_err(emc->dev, "no timing for rate %lu min %lu max %lu\n",
481 			rate, min_rate, max_rate);
482 		return -EINVAL;
483 	}
484 
485 	return timing->rate;
486 }
487 
488 /*
489  * debugfs interface
490  *
491  * The memory controller driver exposes some files in debugfs that can be used
492  * to control the EMC frequency. The top-level directory can be found here:
493  *
494  *   /sys/kernel/debug/emc
495  *
496  * It contains the following files:
497  *
498  *   - available_rates: This file contains a list of valid, space-separated
499  *     EMC frequencies.
500  *
501  *   - min_rate: Writing a value to this file sets the given frequency as the
502  *       floor of the permitted range. If this is higher than the currently
503  *       configured EMC frequency, this will cause the frequency to be
504  *       increased so that it stays within the valid range.
505  *
506  *   - max_rate: Similarily to the min_rate file, writing a value to this file
507  *       sets the given frequency as the ceiling of the permitted range. If
508  *       the value is lower than the currently configured EMC frequency, this
509  *       will cause the frequency to be decreased so that it stays within the
510  *       valid range.
511  */
512 
513 static bool tegra_emc_validate_rate(struct tegra_emc *emc, unsigned long rate)
514 {
515 	unsigned int i;
516 
517 	for (i = 0; i < emc->num_timings; i++)
518 		if (rate == emc->timings[i].rate)
519 			return true;
520 
521 	return false;
522 }
523 
524 static int tegra_emc_debug_available_rates_show(struct seq_file *s, void *data)
525 {
526 	struct tegra_emc *emc = s->private;
527 	const char *prefix = "";
528 	unsigned int i;
529 
530 	for (i = 0; i < emc->num_timings; i++) {
531 		seq_printf(s, "%s%lu", prefix, emc->timings[i].rate);
532 		prefix = " ";
533 	}
534 
535 	seq_puts(s, "\n");
536 
537 	return 0;
538 }
539 
540 static int tegra_emc_debug_available_rates_open(struct inode *inode,
541 						struct file *file)
542 {
543 	return single_open(file, tegra_emc_debug_available_rates_show,
544 			   inode->i_private);
545 }
546 
547 static const struct file_operations tegra_emc_debug_available_rates_fops = {
548 	.open = tegra_emc_debug_available_rates_open,
549 	.read = seq_read,
550 	.llseek = seq_lseek,
551 	.release = single_release,
552 };
553 
554 static int tegra_emc_debug_min_rate_get(void *data, u64 *rate)
555 {
556 	struct tegra_emc *emc = data;
557 
558 	*rate = emc->debugfs.min_rate;
559 
560 	return 0;
561 }
562 
563 static int tegra_emc_debug_min_rate_set(void *data, u64 rate)
564 {
565 	struct tegra_emc *emc = data;
566 	int err;
567 
568 	if (!tegra_emc_validate_rate(emc, rate))
569 		return -EINVAL;
570 
571 	err = clk_set_min_rate(emc->clk, rate);
572 	if (err < 0)
573 		return err;
574 
575 	emc->debugfs.min_rate = rate;
576 
577 	return 0;
578 }
579 
580 DEFINE_SIMPLE_ATTRIBUTE(tegra_emc_debug_min_rate_fops,
581 			tegra_emc_debug_min_rate_get,
582 			tegra_emc_debug_min_rate_set, "%llu\n");
583 
584 static int tegra_emc_debug_max_rate_get(void *data, u64 *rate)
585 {
586 	struct tegra_emc *emc = data;
587 
588 	*rate = emc->debugfs.max_rate;
589 
590 	return 0;
591 }
592 
593 static int tegra_emc_debug_max_rate_set(void *data, u64 rate)
594 {
595 	struct tegra_emc *emc = data;
596 	int err;
597 
598 	if (!tegra_emc_validate_rate(emc, rate))
599 		return -EINVAL;
600 
601 	err = clk_set_max_rate(emc->clk, rate);
602 	if (err < 0)
603 		return err;
604 
605 	emc->debugfs.max_rate = rate;
606 
607 	return 0;
608 }
609 
610 DEFINE_SIMPLE_ATTRIBUTE(tegra_emc_debug_max_rate_fops,
611 			tegra_emc_debug_max_rate_get,
612 			tegra_emc_debug_max_rate_set, "%llu\n");
613 
614 static void tegra_emc_debugfs_init(struct tegra_emc *emc)
615 {
616 	struct device *dev = emc->dev;
617 	unsigned int i;
618 	int err;
619 
620 	emc->debugfs.min_rate = ULONG_MAX;
621 	emc->debugfs.max_rate = 0;
622 
623 	for (i = 0; i < emc->num_timings; i++) {
624 		if (emc->timings[i].rate < emc->debugfs.min_rate)
625 			emc->debugfs.min_rate = emc->timings[i].rate;
626 
627 		if (emc->timings[i].rate > emc->debugfs.max_rate)
628 			emc->debugfs.max_rate = emc->timings[i].rate;
629 	}
630 
631 	err = clk_set_rate_range(emc->clk, emc->debugfs.min_rate,
632 				 emc->debugfs.max_rate);
633 	if (err < 0) {
634 		dev_err(dev, "failed to set rate range [%lu-%lu] for %pC\n",
635 			emc->debugfs.min_rate, emc->debugfs.max_rate,
636 			emc->clk);
637 	}
638 
639 	emc->debugfs.root = debugfs_create_dir("emc", NULL);
640 	if (!emc->debugfs.root) {
641 		dev_err(emc->dev, "failed to create debugfs directory\n");
642 		return;
643 	}
644 
645 	debugfs_create_file("available_rates", S_IRUGO, emc->debugfs.root,
646 			    emc, &tegra_emc_debug_available_rates_fops);
647 	debugfs_create_file("min_rate", S_IRUGO | S_IWUSR, emc->debugfs.root,
648 			    emc, &tegra_emc_debug_min_rate_fops);
649 	debugfs_create_file("max_rate", S_IRUGO | S_IWUSR, emc->debugfs.root,
650 			    emc, &tegra_emc_debug_max_rate_fops);
651 }
652 
653 static int tegra_emc_probe(struct platform_device *pdev)
654 {
655 	struct device_node *np;
656 	struct tegra_emc *emc;
657 	struct resource *res;
658 	int irq, err;
659 
660 	/* driver has nothing to do in a case of memory timing absence */
661 	if (of_get_child_count(pdev->dev.of_node) == 0) {
662 		dev_info(&pdev->dev,
663 			 "EMC device tree node doesn't have memory timings\n");
664 		return 0;
665 	}
666 
667 	irq = platform_get_irq(pdev, 0);
668 	if (irq < 0) {
669 		dev_err(&pdev->dev, "interrupt not specified\n");
670 		dev_err(&pdev->dev, "please update your device tree\n");
671 		return irq;
672 	}
673 
674 	np = tegra_emc_find_node_by_ram_code(&pdev->dev);
675 	if (!np)
676 		return -EINVAL;
677 
678 	emc = devm_kzalloc(&pdev->dev, sizeof(*emc), GFP_KERNEL);
679 	if (!emc) {
680 		of_node_put(np);
681 		return -ENOMEM;
682 	}
683 
684 	init_completion(&emc->clk_handshake_complete);
685 	emc->clk_nb.notifier_call = tegra_emc_clk_change_notify;
686 	emc->dev = &pdev->dev;
687 
688 	err = tegra_emc_load_timings_from_dt(emc, np);
689 	of_node_put(np);
690 	if (err)
691 		return err;
692 
693 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
694 	emc->regs = devm_ioremap_resource(&pdev->dev, res);
695 	if (IS_ERR(emc->regs))
696 		return PTR_ERR(emc->regs);
697 
698 	err = emc_setup_hw(emc);
699 	if (err)
700 		return err;
701 
702 	err = devm_request_irq(&pdev->dev, irq, tegra_emc_isr, 0,
703 			       dev_name(&pdev->dev), emc);
704 	if (err) {
705 		dev_err(&pdev->dev, "failed to request IRQ#%u: %d\n", irq, err);
706 		return err;
707 	}
708 
709 	tegra20_clk_set_emc_round_callback(emc_round_rate, emc);
710 
711 	emc->clk = devm_clk_get(&pdev->dev, "emc");
712 	if (IS_ERR(emc->clk)) {
713 		err = PTR_ERR(emc->clk);
714 		dev_err(&pdev->dev, "failed to get emc clock: %d\n", err);
715 		goto unset_cb;
716 	}
717 
718 	err = clk_notifier_register(emc->clk, &emc->clk_nb);
719 	if (err) {
720 		dev_err(&pdev->dev, "failed to register clk notifier: %d\n",
721 			err);
722 		goto unset_cb;
723 	}
724 
725 	platform_set_drvdata(pdev, emc);
726 	tegra_emc_debugfs_init(emc);
727 
728 	return 0;
729 
730 unset_cb:
731 	tegra20_clk_set_emc_round_callback(NULL, NULL);
732 
733 	return err;
734 }
735 
736 static const struct of_device_id tegra_emc_of_match[] = {
737 	{ .compatible = "nvidia,tegra20-emc", },
738 	{},
739 };
740 
741 static struct platform_driver tegra_emc_driver = {
742 	.probe = tegra_emc_probe,
743 	.driver = {
744 		.name = "tegra20-emc",
745 		.of_match_table = tegra_emc_of_match,
746 		.suppress_bind_attrs = true,
747 	},
748 };
749 
750 static int __init tegra_emc_init(void)
751 {
752 	return platform_driver_register(&tegra_emc_driver);
753 }
754 subsys_initcall(tegra_emc_init);
755