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86c22f8c AC |
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 | |
33350e6b | 23 | * is also specified in each PCC table entry. |
86c22f8c | 24 | * |
33350e6b AC |
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 | |
86c22f8c AC |
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> | |
8b0f5788 | 66 | #include <linux/io-64-nonatomic-lo-hi.h> |
86c22f8c AC |
67 | |
68 | #include "mailbox.h" | |
69 | ||
70 | #define MAX_PCC_SUBSPACES 256 | |
86c22f8c AC |
71 | |
72 | static struct mbox_chan *pcc_mbox_channels; | |
73 | ||
8b0f5788 PP |
74 | /* Array of cached virtual address for doorbell registers */ |
75 | static void __iomem **pcc_doorbell_vaddr; | |
76 | ||
86c22f8c AC |
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 | { | |
86c22f8c AC |
88 | if (id < 0 || id > pcc_mbox_ctrl.num_chans) |
89 | return ERR_PTR(-ENOENT); | |
90 | ||
e9c8dc8b | 91 | return &pcc_mbox_channels[id]; |
86c22f8c AC |
92 | } |
93 | ||
86c22f8c AC |
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 | ||
d311a28a | 123 | if (IS_ERR(chan) || chan->cl) { |
33350e6b | 124 | dev_err(dev, "Channel not found for idx: %d\n", subspace_id); |
86c22f8c AC |
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 | ||
8b0f5788 PP |
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 | ||
86c22f8c | 227 | /** |
33350e6b AC |
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. | |
86c22f8c | 233 | * @chan: Pointer to Mailbox channel over which to send data. |
33350e6b AC |
234 | * @data: Client specific data written over channel. Used here |
235 | * only for debug after PCC transaction completes. | |
86c22f8c AC |
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; | |
8b0f5788 | 242 | struct acpi_generic_address *doorbell; |
86c22f8c AC |
243 | u64 doorbell_preserve; |
244 | u64 doorbell_val; | |
245 | u64 doorbell_write; | |
8b0f5788 PP |
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 | } | |
86c22f8c | 253 | |
8b0f5788 | 254 | doorbell = &pcct_ss->doorbell_register; |
86c22f8c AC |
255 | doorbell_preserve = pcct_ss->preserve_mask; |
256 | doorbell_write = pcct_ss->write_mask; | |
257 | ||
33350e6b | 258 | /* Sync notification from OS to Platform. */ |
8b0f5788 PP |
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; | |
86c22f8c AC |
275 | } |
276 | ||
05ae7975 | 277 | static const struct mbox_chan_ops pcc_chan_ops = { |
86c22f8c | 278 | .send_data = pcc_send_data, |
86c22f8c AC |
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 | ||
8b0f5788 PP |
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 | ||
86c22f8c AC |
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++) { | |
8b0f5788 PP |
361 | struct acpi_generic_address *db_reg; |
362 | struct acpi_pcct_hw_reduced *pcct_ss; | |
86c22f8c AC |
363 | pcc_mbox_channels[i].con_priv = pcct_entry; |
364 | pcct_entry = (struct acpi_subtable_header *) | |
365 | ((unsigned long) pcct_entry + pcct_entry->length); | |
8b0f5788 PP |
366 | |
367 | /* If doorbell is in system memory cache the virt address */ | |
368 | pcct_ss = (struct acpi_pcct_hw_reduced *)pcct_entry; | |
369 | db_reg = &pcct_ss->doorbell_register; | |
370 | if (db_reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) | |
371 | pcc_doorbell_vaddr[i] = acpi_os_ioremap(db_reg->address, | |
372 | db_reg->bit_width/8); | |
86c22f8c AC |
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; | |
86c22f8c AC |
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) { | |
efd756da | 432 | pr_debug("ACPI PCC probe failed.\n"); |
86c22f8c AC |
433 | return -ENODEV; |
434 | } | |
435 | ||
436 | pcc_pdev = platform_create_bundle(&pcc_mbox_driver, | |
437 | pcc_mbox_probe, NULL, 0, NULL, 0); | |
438 | ||
356d5d28 | 439 | if (IS_ERR(pcc_pdev)) { |
efd756da | 440 | pr_debug("Err creating PCC platform bundle\n"); |
356d5d28 | 441 | return PTR_ERR(pcc_pdev); |
86c22f8c AC |
442 | } |
443 | ||
444 | return 0; | |
445 | } | |
d3c68f21 AC |
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); |