xref: /openbmc/linux/drivers/net/ethernet/sfc/nic.c (revision be58f710)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /****************************************************************************
3  * Driver for Solarflare network controllers and boards
4  * Copyright 2005-2006 Fen Systems Ltd.
5  * Copyright 2006-2013 Solarflare Communications Inc.
6  */
7 
8 #include <linux/bitops.h>
9 #include <linux/delay.h>
10 #include <linux/interrupt.h>
11 #include <linux/pci.h>
12 #include <linux/module.h>
13 #include <linux/seq_file.h>
14 #include <linux/cpu_rmap.h>
15 #include "net_driver.h"
16 #include "bitfield.h"
17 #include "efx.h"
18 #include "nic.h"
19 #include "ef10_regs.h"
20 #include "farch_regs.h"
21 #include "io.h"
22 #include "workarounds.h"
23 #include "mcdi_pcol.h"
24 
25 /**************************************************************************
26  *
27  * Generic buffer handling
28  * These buffers are used for interrupt status, MAC stats, etc.
29  *
30  **************************************************************************/
31 
32 int efx_nic_alloc_buffer(struct efx_nic *efx, struct efx_buffer *buffer,
33 			 unsigned int len, gfp_t gfp_flags)
34 {
35 	buffer->addr = dma_alloc_coherent(&efx->pci_dev->dev, len,
36 					  &buffer->dma_addr, gfp_flags);
37 	if (!buffer->addr)
38 		return -ENOMEM;
39 	buffer->len = len;
40 	return 0;
41 }
42 
43 void efx_nic_free_buffer(struct efx_nic *efx, struct efx_buffer *buffer)
44 {
45 	if (buffer->addr) {
46 		dma_free_coherent(&efx->pci_dev->dev, buffer->len,
47 				  buffer->addr, buffer->dma_addr);
48 		buffer->addr = NULL;
49 	}
50 }
51 
52 /* Check whether an event is present in the eventq at the current
53  * read pointer.  Only useful for self-test.
54  */
55 bool efx_nic_event_present(struct efx_channel *channel)
56 {
57 	return efx_event_present(efx_event(channel, channel->eventq_read_ptr));
58 }
59 
60 void efx_nic_event_test_start(struct efx_channel *channel)
61 {
62 	channel->event_test_cpu = -1;
63 	smp_wmb();
64 	channel->efx->type->ev_test_generate(channel);
65 }
66 
67 int efx_nic_irq_test_start(struct efx_nic *efx)
68 {
69 	efx->last_irq_cpu = -1;
70 	smp_wmb();
71 	return efx->type->irq_test_generate(efx);
72 }
73 
74 /* Hook interrupt handler(s)
75  * Try MSI and then legacy interrupts.
76  */
77 int efx_nic_init_interrupt(struct efx_nic *efx)
78 {
79 	struct efx_channel *channel;
80 	unsigned int n_irqs;
81 	int rc;
82 
83 	if (!EFX_INT_MODE_USE_MSI(efx)) {
84 		rc = request_irq(efx->legacy_irq,
85 				 efx->type->irq_handle_legacy, IRQF_SHARED,
86 				 efx->name, efx);
87 		if (rc) {
88 			netif_err(efx, drv, efx->net_dev,
89 				  "failed to hook legacy IRQ %d\n",
90 				  efx->pci_dev->irq);
91 			goto fail1;
92 		}
93 		efx->irqs_hooked = true;
94 		return 0;
95 	}
96 
97 #ifdef CONFIG_RFS_ACCEL
98 	if (efx->interrupt_mode == EFX_INT_MODE_MSIX) {
99 		efx->net_dev->rx_cpu_rmap =
100 			alloc_irq_cpu_rmap(efx->n_rx_channels);
101 		if (!efx->net_dev->rx_cpu_rmap) {
102 			rc = -ENOMEM;
103 			goto fail1;
104 		}
105 	}
106 #endif
107 
108 	/* Hook MSI or MSI-X interrupt */
109 	n_irqs = 0;
110 	efx_for_each_channel(channel, efx) {
111 		rc = request_irq(channel->irq, efx->type->irq_handle_msi,
112 				 IRQF_PROBE_SHARED, /* Not shared */
113 				 efx->msi_context[channel->channel].name,
114 				 &efx->msi_context[channel->channel]);
115 		if (rc) {
116 			netif_err(efx, drv, efx->net_dev,
117 				  "failed to hook IRQ %d\n", channel->irq);
118 			goto fail2;
119 		}
120 		++n_irqs;
121 
122 #ifdef CONFIG_RFS_ACCEL
123 		if (efx->interrupt_mode == EFX_INT_MODE_MSIX &&
124 		    channel->channel < efx->n_rx_channels) {
125 			rc = irq_cpu_rmap_add(efx->net_dev->rx_cpu_rmap,
126 					      channel->irq);
127 			if (rc)
128 				goto fail2;
129 		}
130 #endif
131 	}
132 
133 	efx->irqs_hooked = true;
134 	return 0;
135 
136  fail2:
137 #ifdef CONFIG_RFS_ACCEL
138 	free_irq_cpu_rmap(efx->net_dev->rx_cpu_rmap);
139 	efx->net_dev->rx_cpu_rmap = NULL;
140 #endif
141 	efx_for_each_channel(channel, efx) {
142 		if (n_irqs-- == 0)
143 			break;
144 		free_irq(channel->irq, &efx->msi_context[channel->channel]);
145 	}
146  fail1:
147 	return rc;
148 }
149 
150 void efx_nic_fini_interrupt(struct efx_nic *efx)
151 {
152 	struct efx_channel *channel;
153 
154 #ifdef CONFIG_RFS_ACCEL
155 	free_irq_cpu_rmap(efx->net_dev->rx_cpu_rmap);
156 	efx->net_dev->rx_cpu_rmap = NULL;
157 #endif
158 
159 	if (!efx->irqs_hooked)
160 		return;
161 	if (EFX_INT_MODE_USE_MSI(efx)) {
162 		/* Disable MSI/MSI-X interrupts */
163 		efx_for_each_channel(channel, efx)
164 			free_irq(channel->irq,
165 				 &efx->msi_context[channel->channel]);
166 	} else {
167 		/* Disable legacy interrupt */
168 		free_irq(efx->legacy_irq, efx);
169 	}
170 	efx->irqs_hooked = false;
171 }
172 
173 /* Register dump */
174 
175 #define REGISTER_REVISION_FA	1
176 #define REGISTER_REVISION_FB	2
177 #define REGISTER_REVISION_FC	3
178 #define REGISTER_REVISION_FZ	3	/* last Falcon arch revision */
179 #define REGISTER_REVISION_ED	4
180 #define REGISTER_REVISION_EZ	4	/* latest EF10 revision */
181 
182 struct efx_nic_reg {
183 	u32 offset:24;
184 	u32 min_revision:3, max_revision:3;
185 };
186 
187 #define REGISTER(name, arch, min_rev, max_rev) {			\
188 	arch ## R_ ## min_rev ## max_rev ## _ ## name,			\
189 	REGISTER_REVISION_ ## arch ## min_rev,				\
190 	REGISTER_REVISION_ ## arch ## max_rev				\
191 }
192 #define REGISTER_AA(name) REGISTER(name, F, A, A)
193 #define REGISTER_AB(name) REGISTER(name, F, A, B)
194 #define REGISTER_AZ(name) REGISTER(name, F, A, Z)
195 #define REGISTER_BB(name) REGISTER(name, F, B, B)
196 #define REGISTER_BZ(name) REGISTER(name, F, B, Z)
197 #define REGISTER_CZ(name) REGISTER(name, F, C, Z)
198 #define REGISTER_DZ(name) REGISTER(name, E, D, Z)
199 
200 static const struct efx_nic_reg efx_nic_regs[] = {
201 	REGISTER_AZ(ADR_REGION),
202 	REGISTER_AZ(INT_EN_KER),
203 	REGISTER_BZ(INT_EN_CHAR),
204 	REGISTER_AZ(INT_ADR_KER),
205 	REGISTER_BZ(INT_ADR_CHAR),
206 	/* INT_ACK_KER is WO */
207 	/* INT_ISR0 is RC */
208 	REGISTER_AZ(HW_INIT),
209 	REGISTER_CZ(USR_EV_CFG),
210 	REGISTER_AB(EE_SPI_HCMD),
211 	REGISTER_AB(EE_SPI_HADR),
212 	REGISTER_AB(EE_SPI_HDATA),
213 	REGISTER_AB(EE_BASE_PAGE),
214 	REGISTER_AB(EE_VPD_CFG0),
215 	/* EE_VPD_SW_CNTL and EE_VPD_SW_DATA are not used */
216 	/* PMBX_DBG_IADDR and PBMX_DBG_IDATA are indirect */
217 	/* PCIE_CORE_INDIRECT is indirect */
218 	REGISTER_AB(NIC_STAT),
219 	REGISTER_AB(GPIO_CTL),
220 	REGISTER_AB(GLB_CTL),
221 	/* FATAL_INTR_KER and FATAL_INTR_CHAR are partly RC */
222 	REGISTER_BZ(DP_CTRL),
223 	REGISTER_AZ(MEM_STAT),
224 	REGISTER_AZ(CS_DEBUG),
225 	REGISTER_AZ(ALTERA_BUILD),
226 	REGISTER_AZ(CSR_SPARE),
227 	REGISTER_AB(PCIE_SD_CTL0123),
228 	REGISTER_AB(PCIE_SD_CTL45),
229 	REGISTER_AB(PCIE_PCS_CTL_STAT),
230 	/* DEBUG_DATA_OUT is not used */
231 	/* DRV_EV is WO */
232 	REGISTER_AZ(EVQ_CTL),
233 	REGISTER_AZ(EVQ_CNT1),
234 	REGISTER_AZ(EVQ_CNT2),
235 	REGISTER_AZ(BUF_TBL_CFG),
236 	REGISTER_AZ(SRM_RX_DC_CFG),
237 	REGISTER_AZ(SRM_TX_DC_CFG),
238 	REGISTER_AZ(SRM_CFG),
239 	/* BUF_TBL_UPD is WO */
240 	REGISTER_AZ(SRM_UPD_EVQ),
241 	REGISTER_AZ(SRAM_PARITY),
242 	REGISTER_AZ(RX_CFG),
243 	REGISTER_BZ(RX_FILTER_CTL),
244 	/* RX_FLUSH_DESCQ is WO */
245 	REGISTER_AZ(RX_DC_CFG),
246 	REGISTER_AZ(RX_DC_PF_WM),
247 	REGISTER_BZ(RX_RSS_TKEY),
248 	/* RX_NODESC_DROP is RC */
249 	REGISTER_AA(RX_SELF_RST),
250 	/* RX_DEBUG, RX_PUSH_DROP are not used */
251 	REGISTER_CZ(RX_RSS_IPV6_REG1),
252 	REGISTER_CZ(RX_RSS_IPV6_REG2),
253 	REGISTER_CZ(RX_RSS_IPV6_REG3),
254 	/* TX_FLUSH_DESCQ is WO */
255 	REGISTER_AZ(TX_DC_CFG),
256 	REGISTER_AA(TX_CHKSM_CFG),
257 	REGISTER_AZ(TX_CFG),
258 	/* TX_PUSH_DROP is not used */
259 	REGISTER_AZ(TX_RESERVED),
260 	REGISTER_BZ(TX_PACE),
261 	/* TX_PACE_DROP_QID is RC */
262 	REGISTER_BB(TX_VLAN),
263 	REGISTER_BZ(TX_IPFIL_PORTEN),
264 	REGISTER_AB(MD_TXD),
265 	REGISTER_AB(MD_RXD),
266 	REGISTER_AB(MD_CS),
267 	REGISTER_AB(MD_PHY_ADR),
268 	REGISTER_AB(MD_ID),
269 	/* MD_STAT is RC */
270 	REGISTER_AB(MAC_STAT_DMA),
271 	REGISTER_AB(MAC_CTRL),
272 	REGISTER_BB(GEN_MODE),
273 	REGISTER_AB(MAC_MC_HASH_REG0),
274 	REGISTER_AB(MAC_MC_HASH_REG1),
275 	REGISTER_AB(GM_CFG1),
276 	REGISTER_AB(GM_CFG2),
277 	/* GM_IPG and GM_HD are not used */
278 	REGISTER_AB(GM_MAX_FLEN),
279 	/* GM_TEST is not used */
280 	REGISTER_AB(GM_ADR1),
281 	REGISTER_AB(GM_ADR2),
282 	REGISTER_AB(GMF_CFG0),
283 	REGISTER_AB(GMF_CFG1),
284 	REGISTER_AB(GMF_CFG2),
285 	REGISTER_AB(GMF_CFG3),
286 	REGISTER_AB(GMF_CFG4),
287 	REGISTER_AB(GMF_CFG5),
288 	REGISTER_BB(TX_SRC_MAC_CTL),
289 	REGISTER_AB(XM_ADR_LO),
290 	REGISTER_AB(XM_ADR_HI),
291 	REGISTER_AB(XM_GLB_CFG),
292 	REGISTER_AB(XM_TX_CFG),
293 	REGISTER_AB(XM_RX_CFG),
294 	REGISTER_AB(XM_MGT_INT_MASK),
295 	REGISTER_AB(XM_FC),
296 	REGISTER_AB(XM_PAUSE_TIME),
297 	REGISTER_AB(XM_TX_PARAM),
298 	REGISTER_AB(XM_RX_PARAM),
299 	/* XM_MGT_INT_MSK (note no 'A') is RC */
300 	REGISTER_AB(XX_PWR_RST),
301 	REGISTER_AB(XX_SD_CTL),
302 	REGISTER_AB(XX_TXDRV_CTL),
303 	/* XX_PRBS_CTL, XX_PRBS_CHK and XX_PRBS_ERR are not used */
304 	/* XX_CORE_STAT is partly RC */
305 	REGISTER_DZ(BIU_HW_REV_ID),
306 	REGISTER_DZ(MC_DB_LWRD),
307 	REGISTER_DZ(MC_DB_HWRD),
308 };
309 
310 struct efx_nic_reg_table {
311 	u32 offset:24;
312 	u32 min_revision:3, max_revision:3;
313 	u32 step:6, rows:21;
314 };
315 
316 #define REGISTER_TABLE_DIMENSIONS(_, offset, arch, min_rev, max_rev, step, rows) { \
317 	offset,								\
318 	REGISTER_REVISION_ ## arch ## min_rev,				\
319 	REGISTER_REVISION_ ## arch ## max_rev,				\
320 	step, rows							\
321 }
322 #define REGISTER_TABLE(name, arch, min_rev, max_rev)			\
323 	REGISTER_TABLE_DIMENSIONS(					\
324 		name, arch ## R_ ## min_rev ## max_rev ## _ ## name,	\
325 		arch, min_rev, max_rev,					\
326 		arch ## R_ ## min_rev ## max_rev ## _ ## name ## _STEP,	\
327 		arch ## R_ ## min_rev ## max_rev ## _ ## name ## _ROWS)
328 #define REGISTER_TABLE_AA(name) REGISTER_TABLE(name, F, A, A)
329 #define REGISTER_TABLE_AZ(name) REGISTER_TABLE(name, F, A, Z)
330 #define REGISTER_TABLE_BB(name) REGISTER_TABLE(name, F, B, B)
331 #define REGISTER_TABLE_BZ(name) REGISTER_TABLE(name, F, B, Z)
332 #define REGISTER_TABLE_BB_CZ(name)					\
333 	REGISTER_TABLE_DIMENSIONS(name, FR_BZ_ ## name, F, B, B,	\
334 				  FR_BZ_ ## name ## _STEP,		\
335 				  FR_BB_ ## name ## _ROWS),		\
336 	REGISTER_TABLE_DIMENSIONS(name, FR_BZ_ ## name, F, C, Z,	\
337 				  FR_BZ_ ## name ## _STEP,		\
338 				  FR_CZ_ ## name ## _ROWS)
339 #define REGISTER_TABLE_CZ(name) REGISTER_TABLE(name, F, C, Z)
340 #define REGISTER_TABLE_DZ(name) REGISTER_TABLE(name, E, D, Z)
341 
342 static const struct efx_nic_reg_table efx_nic_reg_tables[] = {
343 	/* DRIVER is not used */
344 	/* EVQ_RPTR, TIMER_COMMAND, USR_EV and {RX,TX}_DESC_UPD are WO */
345 	REGISTER_TABLE_BB(TX_IPFIL_TBL),
346 	REGISTER_TABLE_BB(TX_SRC_MAC_TBL),
347 	REGISTER_TABLE_AA(RX_DESC_PTR_TBL_KER),
348 	REGISTER_TABLE_BB_CZ(RX_DESC_PTR_TBL),
349 	REGISTER_TABLE_AA(TX_DESC_PTR_TBL_KER),
350 	REGISTER_TABLE_BB_CZ(TX_DESC_PTR_TBL),
351 	REGISTER_TABLE_AA(EVQ_PTR_TBL_KER),
352 	REGISTER_TABLE_BB_CZ(EVQ_PTR_TBL),
353 	/* We can't reasonably read all of the buffer table (up to 8MB!).
354 	 * However this driver will only use a few entries.  Reading
355 	 * 1K entries allows for some expansion of queue count and
356 	 * size before we need to change the version. */
357 	REGISTER_TABLE_DIMENSIONS(BUF_FULL_TBL_KER, FR_AA_BUF_FULL_TBL_KER,
358 				  F, A, A, 8, 1024),
359 	REGISTER_TABLE_DIMENSIONS(BUF_FULL_TBL, FR_BZ_BUF_FULL_TBL,
360 				  F, B, Z, 8, 1024),
361 	REGISTER_TABLE_CZ(RX_MAC_FILTER_TBL0),
362 	REGISTER_TABLE_BB_CZ(TIMER_TBL),
363 	REGISTER_TABLE_BB_CZ(TX_PACE_TBL),
364 	REGISTER_TABLE_BZ(RX_INDIRECTION_TBL),
365 	/* TX_FILTER_TBL0 is huge and not used by this driver */
366 	REGISTER_TABLE_CZ(TX_MAC_FILTER_TBL0),
367 	REGISTER_TABLE_CZ(MC_TREG_SMEM),
368 	/* MSIX_PBA_TABLE is not mapped */
369 	/* SRM_DBG is not mapped (and is redundant with BUF_FLL_TBL) */
370 	REGISTER_TABLE_BZ(RX_FILTER_TBL0),
371 	REGISTER_TABLE_DZ(BIU_MC_SFT_STATUS),
372 };
373 
374 size_t efx_nic_get_regs_len(struct efx_nic *efx)
375 {
376 	const struct efx_nic_reg *reg;
377 	const struct efx_nic_reg_table *table;
378 	size_t len = 0;
379 
380 	for (reg = efx_nic_regs;
381 	     reg < efx_nic_regs + ARRAY_SIZE(efx_nic_regs);
382 	     reg++)
383 		if (efx->type->revision >= reg->min_revision &&
384 		    efx->type->revision <= reg->max_revision)
385 			len += sizeof(efx_oword_t);
386 
387 	for (table = efx_nic_reg_tables;
388 	     table < efx_nic_reg_tables + ARRAY_SIZE(efx_nic_reg_tables);
389 	     table++)
390 		if (efx->type->revision >= table->min_revision &&
391 		    efx->type->revision <= table->max_revision)
392 			len += table->rows * min_t(size_t, table->step, 16);
393 
394 	return len;
395 }
396 
397 void efx_nic_get_regs(struct efx_nic *efx, void *buf)
398 {
399 	const struct efx_nic_reg *reg;
400 	const struct efx_nic_reg_table *table;
401 
402 	for (reg = efx_nic_regs;
403 	     reg < efx_nic_regs + ARRAY_SIZE(efx_nic_regs);
404 	     reg++) {
405 		if (efx->type->revision >= reg->min_revision &&
406 		    efx->type->revision <= reg->max_revision) {
407 			efx_reado(efx, (efx_oword_t *)buf, reg->offset);
408 			buf += sizeof(efx_oword_t);
409 		}
410 	}
411 
412 	for (table = efx_nic_reg_tables;
413 	     table < efx_nic_reg_tables + ARRAY_SIZE(efx_nic_reg_tables);
414 	     table++) {
415 		size_t size, i;
416 
417 		if (!(efx->type->revision >= table->min_revision &&
418 		      efx->type->revision <= table->max_revision))
419 			continue;
420 
421 		size = min_t(size_t, table->step, 16);
422 
423 		for (i = 0; i < table->rows; i++) {
424 			switch (table->step) {
425 			case 4: /* 32-bit SRAM */
426 				efx_readd(efx, buf, table->offset + 4 * i);
427 				break;
428 			case 8: /* 64-bit SRAM */
429 				efx_sram_readq(efx,
430 					       efx->membase + table->offset,
431 					       buf, i);
432 				break;
433 			case 16: /* 128-bit-readable register */
434 				efx_reado_table(efx, buf, table->offset, i);
435 				break;
436 			case 32: /* 128-bit register, interleaved */
437 				efx_reado_table(efx, buf, table->offset, 2 * i);
438 				break;
439 			default:
440 				WARN_ON(1);
441 				return;
442 			}
443 			buf += size;
444 		}
445 	}
446 }
447 
448 /**
449  * efx_nic_describe_stats - Describe supported statistics for ethtool
450  * @desc: Array of &struct efx_hw_stat_desc describing the statistics
451  * @count: Length of the @desc array
452  * @mask: Bitmask of which elements of @desc are enabled
453  * @names: Buffer to copy names to, or %NULL.  The names are copied
454  *	starting at intervals of %ETH_GSTRING_LEN bytes.
455  *
456  * Returns the number of visible statistics, i.e. the number of set
457  * bits in the first @count bits of @mask for which a name is defined.
458  */
459 size_t efx_nic_describe_stats(const struct efx_hw_stat_desc *desc, size_t count,
460 			      const unsigned long *mask, u8 *names)
461 {
462 	size_t visible = 0;
463 	size_t index;
464 
465 	for_each_set_bit(index, mask, count) {
466 		if (desc[index].name) {
467 			if (names) {
468 				strlcpy(names, desc[index].name,
469 					ETH_GSTRING_LEN);
470 				names += ETH_GSTRING_LEN;
471 			}
472 			++visible;
473 		}
474 	}
475 
476 	return visible;
477 }
478 
479 /**
480  * efx_nic_copy_stats - Copy stats from the DMA buffer in to an
481  *	intermediate buffer. This is used to get a consistent
482  *	set of stats while the DMA buffer can be written at any time
483  *	by the NIC.
484  * @efx: The associated NIC.
485  * @dest: Destination buffer. Must be the same size as the DMA buffer.
486  */
487 int efx_nic_copy_stats(struct efx_nic *efx, __le64 *dest)
488 {
489 	__le64 *dma_stats = efx->stats_buffer.addr;
490 	__le64 generation_start, generation_end;
491 	int rc = 0, retry;
492 
493 	if (!dest)
494 		return 0;
495 
496 	if (!dma_stats)
497 		goto return_zeroes;
498 
499 	/* If we're unlucky enough to read statistics during the DMA, wait
500 	 * up to 10ms for it to finish (typically takes <500us)
501 	 */
502 	for (retry = 0; retry < 100; ++retry) {
503 		generation_end = dma_stats[efx->num_mac_stats - 1];
504 		if (generation_end == EFX_MC_STATS_GENERATION_INVALID)
505 			goto return_zeroes;
506 		rmb();
507 		memcpy(dest, dma_stats, efx->num_mac_stats * sizeof(__le64));
508 		rmb();
509 		generation_start = dma_stats[MC_CMD_MAC_GENERATION_START];
510 		if (generation_end == generation_start)
511 			return 0; /* return good data */
512 		udelay(100);
513 	}
514 
515 	rc = -EIO;
516 
517 return_zeroes:
518 	memset(dest, 0, efx->num_mac_stats * sizeof(u64));
519 	return rc;
520 }
521 
522 /**
523  * efx_nic_update_stats - Convert statistics DMA buffer to array of u64
524  * @desc: Array of &struct efx_hw_stat_desc describing the DMA buffer
525  *	layout.  DMA widths of 0, 16, 32 and 64 are supported; where
526  *	the width is specified as 0 the corresponding element of
527  *	@stats is not updated.
528  * @count: Length of the @desc array
529  * @mask: Bitmask of which elements of @desc are enabled
530  * @stats: Buffer to update with the converted statistics.  The length
531  *	of this array must be at least @count.
532  * @dma_buf: DMA buffer containing hardware statistics
533  * @accumulate: If set, the converted values will be added rather than
534  *	directly stored to the corresponding elements of @stats
535  */
536 void efx_nic_update_stats(const struct efx_hw_stat_desc *desc, size_t count,
537 			  const unsigned long *mask,
538 			  u64 *stats, const void *dma_buf, bool accumulate)
539 {
540 	size_t index;
541 
542 	for_each_set_bit(index, mask, count) {
543 		if (desc[index].dma_width) {
544 			const void *addr = dma_buf + desc[index].offset;
545 			u64 val;
546 
547 			switch (desc[index].dma_width) {
548 			case 16:
549 				val = le16_to_cpup((__le16 *)addr);
550 				break;
551 			case 32:
552 				val = le32_to_cpup((__le32 *)addr);
553 				break;
554 			case 64:
555 				val = le64_to_cpup((__le64 *)addr);
556 				break;
557 			default:
558 				WARN_ON(1);
559 				val = 0;
560 				break;
561 			}
562 
563 			if (accumulate)
564 				stats[index] += val;
565 			else
566 				stats[index] = val;
567 		}
568 	}
569 }
570 
571 void efx_nic_fix_nodesc_drop_stat(struct efx_nic *efx, u64 *rx_nodesc_drops)
572 {
573 	/* if down, or this is the first update after coming up */
574 	if (!(efx->net_dev->flags & IFF_UP) || !efx->rx_nodesc_drops_prev_state)
575 		efx->rx_nodesc_drops_while_down +=
576 			*rx_nodesc_drops - efx->rx_nodesc_drops_total;
577 	efx->rx_nodesc_drops_total = *rx_nodesc_drops;
578 	efx->rx_nodesc_drops_prev_state = !!(efx->net_dev->flags & IFF_UP);
579 	*rx_nodesc_drops -= efx->rx_nodesc_drops_while_down;
580 }
581