1 /***********************license start***************
2  * Author: Cavium Networks
3  *
4  * Contact: support@caviumnetworks.com
5  * This file is part of the OCTEON SDK
6  *
7  * Copyright (c) 2003-2008 Cavium Networks
8  *
9  * This file is free software; you can redistribute it and/or modify
10  * it under the terms of the GNU General Public License, Version 2, as
11  * published by the Free Software Foundation.
12  *
13  * This file is distributed in the hope that it will be useful, but
14  * AS-IS and WITHOUT ANY WARRANTY; without even the implied warranty
15  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, TITLE, or
16  * NONINFRINGEMENT.  See the GNU General Public License for more
17  * details.
18  *
19  * You should have received a copy of the GNU General Public License
20  * along with this file; if not, write to the Free Software
21  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
22  * or visit http://www.gnu.org/licenses/.
23  *
24  * This file may also be available under a different license from Cavium.
25  * Contact Cavium Networks for more information
26  ***********************license end**************************************/
27 
28 /*
29  * Functions for RGMII/GMII/MII initialization, configuration,
30  * and monitoring.
31  */
32 #include <asm/octeon/octeon.h>
33 
34 #include <asm/octeon/cvmx-config.h>
35 
36 
37 #include <asm/octeon/cvmx-mdio.h>
38 #include <asm/octeon/cvmx-pko.h>
39 #include <asm/octeon/cvmx-helper.h>
40 #include <asm/octeon/cvmx-helper-board.h>
41 
42 #include <asm/octeon/cvmx-npi-defs.h>
43 #include <asm/octeon/cvmx-gmxx-defs.h>
44 #include <asm/octeon/cvmx-asxx-defs.h>
45 #include <asm/octeon/cvmx-dbg-defs.h>
46 
47 void __cvmx_interrupt_gmxx_enable(int interface);
48 void __cvmx_interrupt_asxx_enable(int block);
49 
50 /**
51  * Probe RGMII ports and determine the number present
52  *
53  * @interface: Interface to probe
54  *
55  * Returns Number of RGMII/GMII/MII ports (0-4).
56  */
57 int __cvmx_helper_rgmii_probe(int interface)
58 {
59 	int num_ports = 0;
60 	union cvmx_gmxx_inf_mode mode;
61 	mode.u64 = cvmx_read_csr(CVMX_GMXX_INF_MODE(interface));
62 
63 	if (mode.s.type) {
64 		if (OCTEON_IS_MODEL(OCTEON_CN38XX)
65 		    || OCTEON_IS_MODEL(OCTEON_CN58XX)) {
66 			cvmx_dprintf("ERROR: RGMII initialize called in "
67 				     "SPI interface\n");
68 		} else if (OCTEON_IS_MODEL(OCTEON_CN31XX)
69 			   || OCTEON_IS_MODEL(OCTEON_CN30XX)
70 			   || OCTEON_IS_MODEL(OCTEON_CN50XX)) {
71 			/*
72 			 * On these chips "type" says we're in
73 			 * GMII/MII mode. This limits us to 2 ports
74 			 */
75 			num_ports = 2;
76 		} else {
77 			cvmx_dprintf("ERROR: Unsupported Octeon model in %s\n",
78 				     __func__);
79 		}
80 	} else {
81 		if (OCTEON_IS_MODEL(OCTEON_CN38XX)
82 		    || OCTEON_IS_MODEL(OCTEON_CN58XX)) {
83 			num_ports = 4;
84 		} else if (OCTEON_IS_MODEL(OCTEON_CN31XX)
85 			   || OCTEON_IS_MODEL(OCTEON_CN30XX)
86 			   || OCTEON_IS_MODEL(OCTEON_CN50XX)) {
87 			num_ports = 3;
88 		} else {
89 			cvmx_dprintf("ERROR: Unsupported Octeon model in %s\n",
90 				     __func__);
91 		}
92 	}
93 	return num_ports;
94 }
95 
96 /**
97  * Put an RGMII interface in loopback mode. Internal packets sent
98  * out will be received back again on the same port. Externally
99  * received packets will echo back out.
100  *
101  * @port:   IPD port number to loop.
102  */
103 void cvmx_helper_rgmii_internal_loopback(int port)
104 {
105 	int interface = (port >> 4) & 1;
106 	int index = port & 0xf;
107 	uint64_t tmp;
108 
109 	union cvmx_gmxx_prtx_cfg gmx_cfg;
110 	gmx_cfg.u64 = 0;
111 	gmx_cfg.s.duplex = 1;
112 	gmx_cfg.s.slottime = 1;
113 	gmx_cfg.s.speed = 1;
114 	cvmx_write_csr(CVMX_GMXX_TXX_CLK(index, interface), 1);
115 	cvmx_write_csr(CVMX_GMXX_TXX_SLOT(index, interface), 0x200);
116 	cvmx_write_csr(CVMX_GMXX_TXX_BURST(index, interface), 0x2000);
117 	cvmx_write_csr(CVMX_GMXX_PRTX_CFG(index, interface), gmx_cfg.u64);
118 	tmp = cvmx_read_csr(CVMX_ASXX_PRT_LOOP(interface));
119 	cvmx_write_csr(CVMX_ASXX_PRT_LOOP(interface), (1 << index) | tmp);
120 	tmp = cvmx_read_csr(CVMX_ASXX_TX_PRT_EN(interface));
121 	cvmx_write_csr(CVMX_ASXX_TX_PRT_EN(interface), (1 << index) | tmp);
122 	tmp = cvmx_read_csr(CVMX_ASXX_RX_PRT_EN(interface));
123 	cvmx_write_csr(CVMX_ASXX_RX_PRT_EN(interface), (1 << index) | tmp);
124 	gmx_cfg.s.en = 1;
125 	cvmx_write_csr(CVMX_GMXX_PRTX_CFG(index, interface), gmx_cfg.u64);
126 }
127 
128 /**
129  * Workaround ASX setup errata with CN38XX pass1
130  *
131  * @interface: Interface to setup
132  * @port:      Port to setup (0..3)
133  * @cpu_clock_hz:
134  *		    Chip frequency in Hertz
135  *
136  * Returns Zero on success, negative on failure
137  */
138 static int __cvmx_helper_errata_asx_pass1(int interface, int port,
139 					  int cpu_clock_hz)
140 {
141 	/* Set hi water mark as per errata GMX-4 */
142 	if (cpu_clock_hz >= 325000000 && cpu_clock_hz < 375000000)
143 		cvmx_write_csr(CVMX_ASXX_TX_HI_WATERX(port, interface), 12);
144 	else if (cpu_clock_hz >= 375000000 && cpu_clock_hz < 437000000)
145 		cvmx_write_csr(CVMX_ASXX_TX_HI_WATERX(port, interface), 11);
146 	else if (cpu_clock_hz >= 437000000 && cpu_clock_hz < 550000000)
147 		cvmx_write_csr(CVMX_ASXX_TX_HI_WATERX(port, interface), 10);
148 	else if (cpu_clock_hz >= 550000000 && cpu_clock_hz < 687000000)
149 		cvmx_write_csr(CVMX_ASXX_TX_HI_WATERX(port, interface), 9);
150 	else
151 		cvmx_dprintf("Illegal clock frequency (%d). "
152 			"CVMX_ASXX_TX_HI_WATERX not set\n", cpu_clock_hz);
153 	return 0;
154 }
155 
156 /**
157  * Configure all of the ASX, GMX, and PKO regsiters required
158  * to get RGMII to function on the supplied interface.
159  *
160  * @interface: PKO Interface to configure (0 or 1)
161  *
162  * Returns Zero on success
163  */
164 int __cvmx_helper_rgmii_enable(int interface)
165 {
166 	int num_ports = cvmx_helper_ports_on_interface(interface);
167 	int port;
168 	struct cvmx_sysinfo *sys_info_ptr = cvmx_sysinfo_get();
169 	union cvmx_gmxx_inf_mode mode;
170 	union cvmx_asxx_tx_prt_en asx_tx;
171 	union cvmx_asxx_rx_prt_en asx_rx;
172 
173 	mode.u64 = cvmx_read_csr(CVMX_GMXX_INF_MODE(interface));
174 
175 	if (mode.s.en == 0)
176 		return -1;
177 	if ((OCTEON_IS_MODEL(OCTEON_CN38XX) ||
178 	     OCTEON_IS_MODEL(OCTEON_CN58XX)) && mode.s.type == 1)
179 		/* Ignore SPI interfaces */
180 		return -1;
181 
182 	/* Configure the ASX registers needed to use the RGMII ports */
183 	asx_tx.u64 = 0;
184 	asx_tx.s.prt_en = cvmx_build_mask(num_ports);
185 	cvmx_write_csr(CVMX_ASXX_TX_PRT_EN(interface), asx_tx.u64);
186 
187 	asx_rx.u64 = 0;
188 	asx_rx.s.prt_en = cvmx_build_mask(num_ports);
189 	cvmx_write_csr(CVMX_ASXX_RX_PRT_EN(interface), asx_rx.u64);
190 
191 	/* Configure the GMX registers needed to use the RGMII ports */
192 	for (port = 0; port < num_ports; port++) {
193 		/* Setting of CVMX_GMXX_TXX_THRESH has been moved to
194 		   __cvmx_helper_setup_gmx() */
195 
196 		if (cvmx_octeon_is_pass1())
197 			__cvmx_helper_errata_asx_pass1(interface, port,
198 						       sys_info_ptr->
199 						       cpu_clock_hz);
200 		else {
201 			/*
202 			 * Configure more flexible RGMII preamble
203 			 * checking. Pass 1 doesn't support this
204 			 * feature.
205 			 */
206 			union cvmx_gmxx_rxx_frm_ctl frm_ctl;
207 			frm_ctl.u64 =
208 			    cvmx_read_csr(CVMX_GMXX_RXX_FRM_CTL
209 					  (port, interface));
210 			/* New field, so must be compile time */
211 			frm_ctl.s.pre_free = 1;
212 			cvmx_write_csr(CVMX_GMXX_RXX_FRM_CTL(port, interface),
213 				       frm_ctl.u64);
214 		}
215 
216 		/*
217 		 * Each pause frame transmitted will ask for about 10M
218 		 * bit times before resume.  If buffer space comes
219 		 * available before that time has expired, an XON
220 		 * pause frame (0 time) will be transmitted to restart
221 		 * the flow.
222 		 */
223 		cvmx_write_csr(CVMX_GMXX_TXX_PAUSE_PKT_TIME(port, interface),
224 			       20000);
225 		cvmx_write_csr(CVMX_GMXX_TXX_PAUSE_PKT_INTERVAL
226 			       (port, interface), 19000);
227 
228 		if (OCTEON_IS_MODEL(OCTEON_CN50XX)) {
229 			cvmx_write_csr(CVMX_ASXX_TX_CLK_SETX(port, interface),
230 				       16);
231 			cvmx_write_csr(CVMX_ASXX_RX_CLK_SETX(port, interface),
232 				       16);
233 		} else {
234 			cvmx_write_csr(CVMX_ASXX_TX_CLK_SETX(port, interface),
235 				       24);
236 			cvmx_write_csr(CVMX_ASXX_RX_CLK_SETX(port, interface),
237 				       24);
238 		}
239 	}
240 
241 	__cvmx_helper_setup_gmx(interface, num_ports);
242 
243 	/* enable the ports now */
244 	for (port = 0; port < num_ports; port++) {
245 		union cvmx_gmxx_prtx_cfg gmx_cfg;
246 		cvmx_helper_link_autoconf(cvmx_helper_get_ipd_port
247 					  (interface, port));
248 		gmx_cfg.u64 =
249 		    cvmx_read_csr(CVMX_GMXX_PRTX_CFG(port, interface));
250 		gmx_cfg.s.en = 1;
251 		cvmx_write_csr(CVMX_GMXX_PRTX_CFG(port, interface),
252 			       gmx_cfg.u64);
253 	}
254 	__cvmx_interrupt_asxx_enable(interface);
255 	__cvmx_interrupt_gmxx_enable(interface);
256 
257 	return 0;
258 }
259 
260 /**
261  * Return the link state of an IPD/PKO port as returned by
262  * auto negotiation. The result of this function may not match
263  * Octeon's link config if auto negotiation has changed since
264  * the last call to cvmx_helper_link_set().
265  *
266  * @ipd_port: IPD/PKO port to query
267  *
268  * Returns Link state
269  */
270 cvmx_helper_link_info_t __cvmx_helper_rgmii_link_get(int ipd_port)
271 {
272 	int interface = cvmx_helper_get_interface_num(ipd_port);
273 	int index = cvmx_helper_get_interface_index_num(ipd_port);
274 	union cvmx_asxx_prt_loop asxx_prt_loop;
275 
276 	asxx_prt_loop.u64 = cvmx_read_csr(CVMX_ASXX_PRT_LOOP(interface));
277 	if (asxx_prt_loop.s.int_loop & (1 << index)) {
278 		/* Force 1Gbps full duplex on internal loopback */
279 		cvmx_helper_link_info_t result;
280 		result.u64 = 0;
281 		result.s.full_duplex = 1;
282 		result.s.link_up = 1;
283 		result.s.speed = 1000;
284 		return result;
285 	} else
286 		return __cvmx_helper_board_link_get(ipd_port);
287 }
288 
289 /**
290  * Configure an IPD/PKO port for the specified link state. This
291  * function does not influence auto negotiation at the PHY level.
292  * The passed link state must always match the link state returned
293  * by cvmx_helper_link_get(). It is normally best to use
294  * cvmx_helper_link_autoconf() instead.
295  *
296  * @ipd_port:  IPD/PKO port to configure
297  * @link_info: The new link state
298  *
299  * Returns Zero on success, negative on failure
300  */
301 int __cvmx_helper_rgmii_link_set(int ipd_port,
302 				 cvmx_helper_link_info_t link_info)
303 {
304 	int result = 0;
305 	int interface = cvmx_helper_get_interface_num(ipd_port);
306 	int index = cvmx_helper_get_interface_index_num(ipd_port);
307 	union cvmx_gmxx_prtx_cfg original_gmx_cfg;
308 	union cvmx_gmxx_prtx_cfg new_gmx_cfg;
309 	union cvmx_pko_mem_queue_qos pko_mem_queue_qos;
310 	union cvmx_pko_mem_queue_qos pko_mem_queue_qos_save[16];
311 	union cvmx_gmxx_tx_ovr_bp gmx_tx_ovr_bp;
312 	union cvmx_gmxx_tx_ovr_bp gmx_tx_ovr_bp_save;
313 	int i;
314 
315 	/* Ignore speed sets in the simulator */
316 	if (cvmx_sysinfo_get()->board_type == CVMX_BOARD_TYPE_SIM)
317 		return 0;
318 
319 	/* Read the current settings so we know the current enable state */
320 	original_gmx_cfg.u64 =
321 	    cvmx_read_csr(CVMX_GMXX_PRTX_CFG(index, interface));
322 	new_gmx_cfg = original_gmx_cfg;
323 
324 	/* Disable the lowest level RX */
325 	cvmx_write_csr(CVMX_ASXX_RX_PRT_EN(interface),
326 		       cvmx_read_csr(CVMX_ASXX_RX_PRT_EN(interface)) &
327 				     ~(1 << index));
328 
329 	memset(pko_mem_queue_qos_save, 0, sizeof(pko_mem_queue_qos_save));
330 	/* Disable all queues so that TX should become idle */
331 	for (i = 0; i < cvmx_pko_get_num_queues(ipd_port); i++) {
332 		int queue = cvmx_pko_get_base_queue(ipd_port) + i;
333 		cvmx_write_csr(CVMX_PKO_REG_READ_IDX, queue);
334 		pko_mem_queue_qos.u64 = cvmx_read_csr(CVMX_PKO_MEM_QUEUE_QOS);
335 		pko_mem_queue_qos.s.pid = ipd_port;
336 		pko_mem_queue_qos.s.qid = queue;
337 		pko_mem_queue_qos_save[i] = pko_mem_queue_qos;
338 		pko_mem_queue_qos.s.qos_mask = 0;
339 		cvmx_write_csr(CVMX_PKO_MEM_QUEUE_QOS, pko_mem_queue_qos.u64);
340 	}
341 
342 	/* Disable backpressure */
343 	gmx_tx_ovr_bp.u64 = cvmx_read_csr(CVMX_GMXX_TX_OVR_BP(interface));
344 	gmx_tx_ovr_bp_save = gmx_tx_ovr_bp;
345 	gmx_tx_ovr_bp.s.bp &= ~(1 << index);
346 	gmx_tx_ovr_bp.s.en |= 1 << index;
347 	cvmx_write_csr(CVMX_GMXX_TX_OVR_BP(interface), gmx_tx_ovr_bp.u64);
348 	cvmx_read_csr(CVMX_GMXX_TX_OVR_BP(interface));
349 
350 	/*
351 	 * Poll the GMX state machine waiting for it to become
352 	 * idle. Preferably we should only change speed when it is
353 	 * idle. If it doesn't become idle we will still do the speed
354 	 * change, but there is a slight chance that GMX will
355 	 * lockup.
356 	 */
357 	cvmx_write_csr(CVMX_NPI_DBG_SELECT,
358 		       interface * 0x800 + index * 0x100 + 0x880);
359 	CVMX_WAIT_FOR_FIELD64(CVMX_DBG_DATA, union cvmx_dbg_data, data & 7,
360 			==, 0, 10000);
361 	CVMX_WAIT_FOR_FIELD64(CVMX_DBG_DATA, union cvmx_dbg_data, data & 0xf,
362 			==, 0, 10000);
363 
364 	/* Disable the port before we make any changes */
365 	new_gmx_cfg.s.en = 0;
366 	cvmx_write_csr(CVMX_GMXX_PRTX_CFG(index, interface), new_gmx_cfg.u64);
367 	cvmx_read_csr(CVMX_GMXX_PRTX_CFG(index, interface));
368 
369 	/* Set full/half duplex */
370 	if (cvmx_octeon_is_pass1())
371 		/* Half duplex is broken for 38XX Pass 1 */
372 		new_gmx_cfg.s.duplex = 1;
373 	else if (!link_info.s.link_up)
374 		/* Force full duplex on down links */
375 		new_gmx_cfg.s.duplex = 1;
376 	else
377 		new_gmx_cfg.s.duplex = link_info.s.full_duplex;
378 
379 	/* Set the link speed. Anything unknown is set to 1Gbps */
380 	if (link_info.s.speed == 10) {
381 		new_gmx_cfg.s.slottime = 0;
382 		new_gmx_cfg.s.speed = 0;
383 	} else if (link_info.s.speed == 100) {
384 		new_gmx_cfg.s.slottime = 0;
385 		new_gmx_cfg.s.speed = 0;
386 	} else {
387 		new_gmx_cfg.s.slottime = 1;
388 		new_gmx_cfg.s.speed = 1;
389 	}
390 
391 	/* Adjust the clocks */
392 	if (link_info.s.speed == 10) {
393 		cvmx_write_csr(CVMX_GMXX_TXX_CLK(index, interface), 50);
394 		cvmx_write_csr(CVMX_GMXX_TXX_SLOT(index, interface), 0x40);
395 		cvmx_write_csr(CVMX_GMXX_TXX_BURST(index, interface), 0);
396 	} else if (link_info.s.speed == 100) {
397 		cvmx_write_csr(CVMX_GMXX_TXX_CLK(index, interface), 5);
398 		cvmx_write_csr(CVMX_GMXX_TXX_SLOT(index, interface), 0x40);
399 		cvmx_write_csr(CVMX_GMXX_TXX_BURST(index, interface), 0);
400 	} else {
401 		cvmx_write_csr(CVMX_GMXX_TXX_CLK(index, interface), 1);
402 		cvmx_write_csr(CVMX_GMXX_TXX_SLOT(index, interface), 0x200);
403 		cvmx_write_csr(CVMX_GMXX_TXX_BURST(index, interface), 0x2000);
404 	}
405 
406 	if (OCTEON_IS_MODEL(OCTEON_CN30XX) || OCTEON_IS_MODEL(OCTEON_CN50XX)) {
407 		if ((link_info.s.speed == 10) || (link_info.s.speed == 100)) {
408 			union cvmx_gmxx_inf_mode mode;
409 			mode.u64 = cvmx_read_csr(CVMX_GMXX_INF_MODE(interface));
410 
411 	/*
412 	 * Port	 .en  .type  .p0mii  Configuration
413 	 * ----	 ---  -----  ------  -----------------------------------------
414 	 *  X	   0	 X	X    All links are disabled.
415 	 *  0	   1	 X	0    Port 0 is RGMII
416 	 *  0	   1	 X	1    Port 0 is MII
417 	 *  1	   1	 0	X    Ports 1 and 2 are configured as RGMII ports.
418 	 *  1	   1	 1	X    Port 1: GMII/MII; Port 2: disabled. GMII or
419 	 *			     MII port is selected by GMX_PRT1_CFG[SPEED].
420 	 */
421 
422 			/* In MII mode, CLK_CNT = 1. */
423 			if (((index == 0) && (mode.s.p0mii == 1))
424 			    || ((index != 0) && (mode.s.type == 1))) {
425 				cvmx_write_csr(CVMX_GMXX_TXX_CLK
426 					       (index, interface), 1);
427 			}
428 		}
429 	}
430 
431 	/* Do a read to make sure all setup stuff is complete */
432 	cvmx_read_csr(CVMX_GMXX_PRTX_CFG(index, interface));
433 
434 	/* Save the new GMX setting without enabling the port */
435 	cvmx_write_csr(CVMX_GMXX_PRTX_CFG(index, interface), new_gmx_cfg.u64);
436 
437 	/* Enable the lowest level RX */
438 	cvmx_write_csr(CVMX_ASXX_RX_PRT_EN(interface),
439 		       cvmx_read_csr(CVMX_ASXX_RX_PRT_EN(interface)) | (1 <<
440 									index));
441 
442 	/* Re-enable the TX path */
443 	for (i = 0; i < cvmx_pko_get_num_queues(ipd_port); i++) {
444 		int queue = cvmx_pko_get_base_queue(ipd_port) + i;
445 		cvmx_write_csr(CVMX_PKO_REG_READ_IDX, queue);
446 		cvmx_write_csr(CVMX_PKO_MEM_QUEUE_QOS,
447 			       pko_mem_queue_qos_save[i].u64);
448 	}
449 
450 	/* Restore backpressure */
451 	cvmx_write_csr(CVMX_GMXX_TX_OVR_BP(interface), gmx_tx_ovr_bp_save.u64);
452 
453 	/* Restore the GMX enable state. Port config is complete */
454 	new_gmx_cfg.s.en = original_gmx_cfg.s.en;
455 	cvmx_write_csr(CVMX_GMXX_PRTX_CFG(index, interface), new_gmx_cfg.u64);
456 
457 	return result;
458 }
459 
460 /**
461  * Configure a port for internal and/or external loopback. Internal loopback
462  * causes packets sent by the port to be received by Octeon. External loopback
463  * causes packets received from the wire to sent out again.
464  *
465  * @ipd_port: IPD/PKO port to loopback.
466  * @enable_internal:
467  *		   Non zero if you want internal loopback
468  * @enable_external:
469  *		   Non zero if you want external loopback
470  *
471  * Returns Zero on success, negative on failure.
472  */
473 int __cvmx_helper_rgmii_configure_loopback(int ipd_port, int enable_internal,
474 					   int enable_external)
475 {
476 	int interface = cvmx_helper_get_interface_num(ipd_port);
477 	int index = cvmx_helper_get_interface_index_num(ipd_port);
478 	int original_enable;
479 	union cvmx_gmxx_prtx_cfg gmx_cfg;
480 	union cvmx_asxx_prt_loop asxx_prt_loop;
481 
482 	/* Read the current enable state and save it */
483 	gmx_cfg.u64 = cvmx_read_csr(CVMX_GMXX_PRTX_CFG(index, interface));
484 	original_enable = gmx_cfg.s.en;
485 	/* Force port to be disabled */
486 	gmx_cfg.s.en = 0;
487 	if (enable_internal) {
488 		/* Force speed if we're doing internal loopback */
489 		gmx_cfg.s.duplex = 1;
490 		gmx_cfg.s.slottime = 1;
491 		gmx_cfg.s.speed = 1;
492 		cvmx_write_csr(CVMX_GMXX_TXX_CLK(index, interface), 1);
493 		cvmx_write_csr(CVMX_GMXX_TXX_SLOT(index, interface), 0x200);
494 		cvmx_write_csr(CVMX_GMXX_TXX_BURST(index, interface), 0x2000);
495 	}
496 	cvmx_write_csr(CVMX_GMXX_PRTX_CFG(index, interface), gmx_cfg.u64);
497 
498 	/* Set the loopback bits */
499 	asxx_prt_loop.u64 = cvmx_read_csr(CVMX_ASXX_PRT_LOOP(interface));
500 	if (enable_internal)
501 		asxx_prt_loop.s.int_loop |= 1 << index;
502 	else
503 		asxx_prt_loop.s.int_loop &= ~(1 << index);
504 	if (enable_external)
505 		asxx_prt_loop.s.ext_loop |= 1 << index;
506 	else
507 		asxx_prt_loop.s.ext_loop &= ~(1 << index);
508 	cvmx_write_csr(CVMX_ASXX_PRT_LOOP(interface), asxx_prt_loop.u64);
509 
510 	/* Force enables in internal loopback */
511 	if (enable_internal) {
512 		uint64_t tmp;
513 		tmp = cvmx_read_csr(CVMX_ASXX_TX_PRT_EN(interface));
514 		cvmx_write_csr(CVMX_ASXX_TX_PRT_EN(interface),
515 			       (1 << index) | tmp);
516 		tmp = cvmx_read_csr(CVMX_ASXX_RX_PRT_EN(interface));
517 		cvmx_write_csr(CVMX_ASXX_RX_PRT_EN(interface),
518 			       (1 << index) | tmp);
519 		original_enable = 1;
520 	}
521 
522 	/* Restore the enable state */
523 	gmx_cfg.s.en = original_enable;
524 	cvmx_write_csr(CVMX_GMXX_PRTX_CFG(index, interface), gmx_cfg.u64);
525 	return 0;
526 }
527