Merge tag 'powerpc-4.6-5' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc...
[deliverable/linux.git] / drivers / mailbox / pcc.c
1 /*
2 * Copyright (C) 2014 Linaro Ltd.
3 * Author: Ashwin Chaugule <ashwin.chaugule@linaro.org>
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * PCC (Platform Communication Channel) is defined in the ACPI 5.0+
16 * specification. It is a mailbox like mechanism to allow clients
17 * such as CPPC (Collaborative Processor Performance Control), RAS
18 * (Reliability, Availability and Serviceability) and MPST (Memory
19 * Node Power State Table) to talk to the platform (e.g. BMC) through
20 * shared memory regions as defined in the PCC table entries. The PCC
21 * specification supports a Doorbell mechanism for the PCC clients
22 * to notify the platform about new data. This Doorbell information
23 * is also specified in each PCC table entry.
24 *
25 * Typical high level flow of operation is:
26 *
27 * PCC Reads:
28 * * Client tries to acquire a channel lock.
29 * * After it is acquired it writes READ cmd in communication region cmd
30 * address.
31 * * Client issues mbox_send_message() which rings the PCC doorbell
32 * for its PCC channel.
33 * * If command completes, then client has control over channel and
34 * it can proceed with its reads.
35 * * Client releases lock.
36 *
37 * PCC Writes:
38 * * Client tries to acquire channel lock.
39 * * Client writes to its communication region after it acquires a
40 * channel lock.
41 * * Client writes WRITE cmd in communication region cmd address.
42 * * Client issues mbox_send_message() which rings the PCC doorbell
43 * for its PCC channel.
44 * * If command completes, then writes have succeded and it can release
45 * the channel lock.
46 *
47 * There is a Nominal latency defined for each channel which indicates
48 * how long to wait until a command completes. If command is not complete
49 * the client needs to retry or assume failure.
50 *
51 * For more details about PCC, please see the ACPI specification from
52 * http://www.uefi.org/ACPIv5.1 Section 14.
53 *
54 * This file implements PCC as a Mailbox controller and allows for PCC
55 * clients to be implemented as its Mailbox Client Channels.
56 */
57
58 #include <linux/acpi.h>
59 #include <linux/delay.h>
60 #include <linux/io.h>
61 #include <linux/init.h>
62 #include <linux/list.h>
63 #include <linux/platform_device.h>
64 #include <linux/mailbox_controller.h>
65 #include <linux/mailbox_client.h>
66 #include <linux/io-64-nonatomic-lo-hi.h>
67
68 #include "mailbox.h"
69
70 #define MAX_PCC_SUBSPACES 256
71
72 static struct mbox_chan *pcc_mbox_channels;
73
74 /* Array of cached virtual address for doorbell registers */
75 static void __iomem **pcc_doorbell_vaddr;
76
77 static struct mbox_controller pcc_mbox_ctrl = {};
78 /**
79 * get_pcc_channel - Given a PCC subspace idx, get
80 * the respective mbox_channel.
81 * @id: PCC subspace index.
82 *
83 * Return: ERR_PTR(errno) if error, else pointer
84 * to mbox channel.
85 */
86 static struct mbox_chan *get_pcc_channel(int id)
87 {
88 if (id < 0 || id > pcc_mbox_ctrl.num_chans)
89 return ERR_PTR(-ENOENT);
90
91 return &pcc_mbox_channels[id];
92 }
93
94 /**
95 * pcc_mbox_request_channel - PCC clients call this function to
96 * request a pointer to their PCC subspace, from which they
97 * can get the details of communicating with the remote.
98 * @cl: Pointer to Mailbox client, so we know where to bind the
99 * Channel.
100 * @subspace_id: The PCC Subspace index as parsed in the PCC client
101 * ACPI package. This is used to lookup the array of PCC
102 * subspaces as parsed by the PCC Mailbox controller.
103 *
104 * Return: Pointer to the Mailbox Channel if successful or
105 * ERR_PTR.
106 */
107 struct mbox_chan *pcc_mbox_request_channel(struct mbox_client *cl,
108 int subspace_id)
109 {
110 struct device *dev = pcc_mbox_ctrl.dev;
111 struct mbox_chan *chan;
112 unsigned long flags;
113
114 /*
115 * Each PCC Subspace is a Mailbox Channel.
116 * The PCC Clients get their PCC Subspace ID
117 * from their own tables and pass it here.
118 * This returns a pointer to the PCC subspace
119 * for the Client to operate on.
120 */
121 chan = get_pcc_channel(subspace_id);
122
123 if (IS_ERR(chan) || chan->cl) {
124 dev_err(dev, "Channel not found for idx: %d\n", subspace_id);
125 return ERR_PTR(-EBUSY);
126 }
127
128 spin_lock_irqsave(&chan->lock, flags);
129 chan->msg_free = 0;
130 chan->msg_count = 0;
131 chan->active_req = NULL;
132 chan->cl = cl;
133 init_completion(&chan->tx_complete);
134
135 if (chan->txdone_method == TXDONE_BY_POLL && cl->knows_txdone)
136 chan->txdone_method |= TXDONE_BY_ACK;
137
138 spin_unlock_irqrestore(&chan->lock, flags);
139
140 return chan;
141 }
142 EXPORT_SYMBOL_GPL(pcc_mbox_request_channel);
143
144 /**
145 * pcc_mbox_free_channel - Clients call this to free their Channel.
146 *
147 * @chan: Pointer to the mailbox channel as returned by
148 * pcc_mbox_request_channel()
149 */
150 void pcc_mbox_free_channel(struct mbox_chan *chan)
151 {
152 unsigned long flags;
153
154 if (!chan || !chan->cl)
155 return;
156
157 spin_lock_irqsave(&chan->lock, flags);
158 chan->cl = NULL;
159 chan->active_req = NULL;
160 if (chan->txdone_method == (TXDONE_BY_POLL | TXDONE_BY_ACK))
161 chan->txdone_method = TXDONE_BY_POLL;
162
163 spin_unlock_irqrestore(&chan->lock, flags);
164 }
165 EXPORT_SYMBOL_GPL(pcc_mbox_free_channel);
166
167 /*
168 * PCC can be used with perf critical drivers such as CPPC
169 * So it makes sense to locally cache the virtual address and
170 * use it to read/write to PCC registers such as doorbell register
171 *
172 * The below read_register and write_registers are used to read and
173 * write from perf critical registers such as PCC doorbell register
174 */
175 static int read_register(void __iomem *vaddr, u64 *val, unsigned int bit_width)
176 {
177 int ret_val = 0;
178
179 switch (bit_width) {
180 case 8:
181 *val = readb(vaddr);
182 break;
183 case 16:
184 *val = readw(vaddr);
185 break;
186 case 32:
187 *val = readl(vaddr);
188 break;
189 case 64:
190 *val = readq(vaddr);
191 break;
192 default:
193 pr_debug("Error: Cannot read register of %u bit width",
194 bit_width);
195 ret_val = -EFAULT;
196 break;
197 }
198 return ret_val;
199 }
200
201 static int write_register(void __iomem *vaddr, u64 val, unsigned int bit_width)
202 {
203 int ret_val = 0;
204
205 switch (bit_width) {
206 case 8:
207 writeb(val, vaddr);
208 break;
209 case 16:
210 writew(val, vaddr);
211 break;
212 case 32:
213 writel(val, vaddr);
214 break;
215 case 64:
216 writeq(val, vaddr);
217 break;
218 default:
219 pr_debug("Error: Cannot write register of %u bit width",
220 bit_width);
221 ret_val = -EFAULT;
222 break;
223 }
224 return ret_val;
225 }
226
227 /**
228 * pcc_send_data - Called from Mailbox Controller code. Used
229 * here only to ring the channel doorbell. The PCC client
230 * specific read/write is done in the client driver in
231 * order to maintain atomicity over PCC channel once
232 * OS has control over it. See above for flow of operations.
233 * @chan: Pointer to Mailbox channel over which to send data.
234 * @data: Client specific data written over channel. Used here
235 * only for debug after PCC transaction completes.
236 *
237 * Return: Err if something failed else 0 for success.
238 */
239 static int pcc_send_data(struct mbox_chan *chan, void *data)
240 {
241 struct acpi_pcct_hw_reduced *pcct_ss = chan->con_priv;
242 struct acpi_generic_address *doorbell;
243 u64 doorbell_preserve;
244 u64 doorbell_val;
245 u64 doorbell_write;
246 u32 id = chan - pcc_mbox_channels;
247 int ret = 0;
248
249 if (id >= pcc_mbox_ctrl.num_chans) {
250 pr_debug("pcc_send_data: Invalid mbox_chan passed\n");
251 return -ENOENT;
252 }
253
254 doorbell = &pcct_ss->doorbell_register;
255 doorbell_preserve = pcct_ss->preserve_mask;
256 doorbell_write = pcct_ss->write_mask;
257
258 /* Sync notification from OS to Platform. */
259 if (pcc_doorbell_vaddr[id]) {
260 ret = read_register(pcc_doorbell_vaddr[id], &doorbell_val,
261 doorbell->bit_width);
262 if (ret)
263 return ret;
264 ret = write_register(pcc_doorbell_vaddr[id],
265 (doorbell_val & doorbell_preserve) | doorbell_write,
266 doorbell->bit_width);
267 } else {
268 ret = acpi_read(&doorbell_val, doorbell);
269 if (ret)
270 return ret;
271 ret = acpi_write((doorbell_val & doorbell_preserve) | doorbell_write,
272 doorbell);
273 }
274 return ret;
275 }
276
277 static const struct mbox_chan_ops pcc_chan_ops = {
278 .send_data = pcc_send_data,
279 };
280
281 /**
282 * parse_pcc_subspace - Parse the PCC table and verify PCC subspace
283 * entries. There should be one entry per PCC client.
284 * @header: Pointer to the ACPI subtable header under the PCCT.
285 * @end: End of subtable entry.
286 *
287 * Return: 0 for Success, else errno.
288 *
289 * This gets called for each entry in the PCC table.
290 */
291 static int parse_pcc_subspace(struct acpi_subtable_header *header,
292 const unsigned long end)
293 {
294 struct acpi_pcct_hw_reduced *pcct_ss;
295
296 if (pcc_mbox_ctrl.num_chans <= MAX_PCC_SUBSPACES) {
297 pcct_ss = (struct acpi_pcct_hw_reduced *) header;
298
299 if (pcct_ss->header.type !=
300 ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE) {
301 pr_err("Incorrect PCC Subspace type detected\n");
302 return -EINVAL;
303 }
304 }
305
306 return 0;
307 }
308
309 /**
310 * acpi_pcc_probe - Parse the ACPI tree for the PCCT.
311 *
312 * Return: 0 for Success, else errno.
313 */
314 static int __init acpi_pcc_probe(void)
315 {
316 acpi_size pcct_tbl_header_size;
317 struct acpi_table_header *pcct_tbl;
318 struct acpi_subtable_header *pcct_entry;
319 int count, i;
320 acpi_status status = AE_OK;
321
322 /* Search for PCCT */
323 status = acpi_get_table_with_size(ACPI_SIG_PCCT, 0,
324 &pcct_tbl,
325 &pcct_tbl_header_size);
326
327 if (ACPI_FAILURE(status) || !pcct_tbl) {
328 pr_warn("PCCT header not found.\n");
329 return -ENODEV;
330 }
331
332 count = acpi_table_parse_entries(ACPI_SIG_PCCT,
333 sizeof(struct acpi_table_pcct),
334 ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE,
335 parse_pcc_subspace, MAX_PCC_SUBSPACES);
336
337 if (count <= 0) {
338 pr_err("Error parsing PCC subspaces from PCCT\n");
339 return -EINVAL;
340 }
341
342 pcc_mbox_channels = kzalloc(sizeof(struct mbox_chan) *
343 count, GFP_KERNEL);
344
345 if (!pcc_mbox_channels) {
346 pr_err("Could not allocate space for PCC mbox channels\n");
347 return -ENOMEM;
348 }
349
350 pcc_doorbell_vaddr = kcalloc(count, sizeof(void *), GFP_KERNEL);
351 if (!pcc_doorbell_vaddr) {
352 kfree(pcc_mbox_channels);
353 return -ENOMEM;
354 }
355
356 /* Point to the first PCC subspace entry */
357 pcct_entry = (struct acpi_subtable_header *) (
358 (unsigned long) pcct_tbl + sizeof(struct acpi_table_pcct));
359
360 for (i = 0; i < count; i++) {
361 struct acpi_generic_address *db_reg;
362 struct acpi_pcct_hw_reduced *pcct_ss;
363 pcc_mbox_channels[i].con_priv = pcct_entry;
364
365 /* If doorbell is in system memory cache the virt address */
366 pcct_ss = (struct acpi_pcct_hw_reduced *)pcct_entry;
367 db_reg = &pcct_ss->doorbell_register;
368 if (db_reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
369 pcc_doorbell_vaddr[i] = acpi_os_ioremap(db_reg->address,
370 db_reg->bit_width/8);
371 pcct_entry = (struct acpi_subtable_header *)
372 ((unsigned long) pcct_entry + pcct_entry->length);
373 }
374
375 pcc_mbox_ctrl.num_chans = count;
376
377 pr_info("Detected %d PCC Subspaces\n", pcc_mbox_ctrl.num_chans);
378
379 return 0;
380 }
381
382 /**
383 * pcc_mbox_probe - Called when we find a match for the
384 * PCCT platform device. This is purely used to represent
385 * the PCCT as a virtual device for registering with the
386 * generic Mailbox framework.
387 *
388 * @pdev: Pointer to platform device returned when a match
389 * is found.
390 *
391 * Return: 0 for Success, else errno.
392 */
393 static int pcc_mbox_probe(struct platform_device *pdev)
394 {
395 int ret = 0;
396
397 pcc_mbox_ctrl.chans = pcc_mbox_channels;
398 pcc_mbox_ctrl.ops = &pcc_chan_ops;
399 pcc_mbox_ctrl.dev = &pdev->dev;
400
401 pr_info("Registering PCC driver as Mailbox controller\n");
402 ret = mbox_controller_register(&pcc_mbox_ctrl);
403
404 if (ret) {
405 pr_err("Err registering PCC as Mailbox controller: %d\n", ret);
406 ret = -ENODEV;
407 }
408
409 return ret;
410 }
411
412 struct platform_driver pcc_mbox_driver = {
413 .probe = pcc_mbox_probe,
414 .driver = {
415 .name = "PCCT",
416 .owner = THIS_MODULE,
417 },
418 };
419
420 static int __init pcc_init(void)
421 {
422 int ret;
423 struct platform_device *pcc_pdev;
424
425 if (acpi_disabled)
426 return -ENODEV;
427
428 /* Check if PCC support is available. */
429 ret = acpi_pcc_probe();
430
431 if (ret) {
432 pr_debug("ACPI PCC probe failed.\n");
433 return -ENODEV;
434 }
435
436 pcc_pdev = platform_create_bundle(&pcc_mbox_driver,
437 pcc_mbox_probe, NULL, 0, NULL, 0);
438
439 if (IS_ERR(pcc_pdev)) {
440 pr_debug("Err creating PCC platform bundle\n");
441 return PTR_ERR(pcc_pdev);
442 }
443
444 return 0;
445 }
446
447 /*
448 * Make PCC init postcore so that users of this mailbox
449 * such as the ACPI Processor driver have it available
450 * at their init.
451 */
452 postcore_initcall(pcc_init);
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