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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. See pcc_send_data() | |
24 | * and pcc_tx_done() for basic mode of operation. | |
25 | * | |
26 | * For more details about PCC, please see the ACPI specification from | |
27 | * http://www.uefi.org/ACPIv5.1 Section 14. | |
28 | * | |
29 | * This file implements PCC as a Mailbox controller and allows for PCC | |
30 | * clients to be implemented as its Mailbox Client Channels. | |
31 | */ | |
32 | ||
33 | #include <linux/acpi.h> | |
34 | #include <linux/delay.h> | |
35 | #include <linux/io.h> | |
36 | #include <linux/init.h> | |
37 | #include <linux/list.h> | |
38 | #include <linux/platform_device.h> | |
39 | #include <linux/mailbox_controller.h> | |
40 | #include <linux/mailbox_client.h> | |
41 | ||
42 | #include "mailbox.h" | |
43 | ||
44 | #define MAX_PCC_SUBSPACES 256 | |
45 | #define PCCS_SS_SIG_MAGIC 0x50434300 | |
46 | #define PCC_CMD_COMPLETE 0x1 | |
47 | ||
48 | static struct mbox_chan *pcc_mbox_channels; | |
49 | ||
50 | static struct mbox_controller pcc_mbox_ctrl = {}; | |
51 | /** | |
52 | * get_pcc_channel - Given a PCC subspace idx, get | |
53 | * the respective mbox_channel. | |
54 | * @id: PCC subspace index. | |
55 | * | |
56 | * Return: ERR_PTR(errno) if error, else pointer | |
57 | * to mbox channel. | |
58 | */ | |
59 | static struct mbox_chan *get_pcc_channel(int id) | |
60 | { | |
61 | struct mbox_chan *pcc_chan; | |
62 | ||
63 | if (id < 0 || id > pcc_mbox_ctrl.num_chans) | |
64 | return ERR_PTR(-ENOENT); | |
65 | ||
66 | pcc_chan = (struct mbox_chan *) | |
67 | (unsigned long) pcc_mbox_channels + | |
68 | (id * sizeof(*pcc_chan)); | |
69 | ||
70 | return pcc_chan; | |
71 | } | |
72 | ||
73 | /** | |
74 | * get_subspace_id - Given a Mailbox channel, find out the | |
75 | * PCC subspace id. | |
76 | * @chan: Pointer to Mailbox Channel from which we want | |
77 | * the index. | |
78 | * Return: Errno if not found, else positive index number. | |
79 | */ | |
80 | static int get_subspace_id(struct mbox_chan *chan) | |
81 | { | |
82 | unsigned int id = chan - pcc_mbox_channels; | |
83 | ||
84 | if (id < 0 || id > pcc_mbox_ctrl.num_chans) | |
85 | return -ENOENT; | |
86 | ||
87 | return id; | |
88 | } | |
89 | ||
90 | /** | |
91 | * pcc_mbox_request_channel - PCC clients call this function to | |
92 | * request a pointer to their PCC subspace, from which they | |
93 | * can get the details of communicating with the remote. | |
94 | * @cl: Pointer to Mailbox client, so we know where to bind the | |
95 | * Channel. | |
96 | * @subspace_id: The PCC Subspace index as parsed in the PCC client | |
97 | * ACPI package. This is used to lookup the array of PCC | |
98 | * subspaces as parsed by the PCC Mailbox controller. | |
99 | * | |
100 | * Return: Pointer to the Mailbox Channel if successful or | |
101 | * ERR_PTR. | |
102 | */ | |
103 | struct mbox_chan *pcc_mbox_request_channel(struct mbox_client *cl, | |
104 | int subspace_id) | |
105 | { | |
106 | struct device *dev = pcc_mbox_ctrl.dev; | |
107 | struct mbox_chan *chan; | |
108 | unsigned long flags; | |
109 | ||
110 | /* | |
111 | * Each PCC Subspace is a Mailbox Channel. | |
112 | * The PCC Clients get their PCC Subspace ID | |
113 | * from their own tables and pass it here. | |
114 | * This returns a pointer to the PCC subspace | |
115 | * for the Client to operate on. | |
116 | */ | |
117 | chan = get_pcc_channel(subspace_id); | |
118 | ||
119 | if (!chan || chan->cl) { | |
120 | dev_err(dev, "%s: PCC mailbox not free\n", __func__); | |
121 | return ERR_PTR(-EBUSY); | |
122 | } | |
123 | ||
124 | spin_lock_irqsave(&chan->lock, flags); | |
125 | chan->msg_free = 0; | |
126 | chan->msg_count = 0; | |
127 | chan->active_req = NULL; | |
128 | chan->cl = cl; | |
129 | init_completion(&chan->tx_complete); | |
130 | ||
131 | if (chan->txdone_method == TXDONE_BY_POLL && cl->knows_txdone) | |
132 | chan->txdone_method |= TXDONE_BY_ACK; | |
133 | ||
134 | spin_unlock_irqrestore(&chan->lock, flags); | |
135 | ||
136 | return chan; | |
137 | } | |
138 | EXPORT_SYMBOL_GPL(pcc_mbox_request_channel); | |
139 | ||
140 | /** | |
141 | * pcc_mbox_free_channel - Clients call this to free their Channel. | |
142 | * | |
143 | * @chan: Pointer to the mailbox channel as returned by | |
144 | * pcc_mbox_request_channel() | |
145 | */ | |
146 | void pcc_mbox_free_channel(struct mbox_chan *chan) | |
147 | { | |
148 | unsigned long flags; | |
149 | ||
150 | if (!chan || !chan->cl) | |
151 | return; | |
152 | ||
153 | spin_lock_irqsave(&chan->lock, flags); | |
154 | chan->cl = NULL; | |
155 | chan->active_req = NULL; | |
156 | if (chan->txdone_method == (TXDONE_BY_POLL | TXDONE_BY_ACK)) | |
157 | chan->txdone_method = TXDONE_BY_POLL; | |
158 | ||
159 | spin_unlock_irqrestore(&chan->lock, flags); | |
160 | } | |
161 | EXPORT_SYMBOL_GPL(pcc_mbox_free_channel); | |
162 | ||
163 | /** | |
164 | * pcc_tx_done - Callback from Mailbox controller code to | |
165 | * check if PCC message transmission completed. | |
166 | * @chan: Pointer to Mailbox channel on which previous | |
167 | * transmission occurred. | |
168 | * | |
169 | * Return: TRUE if succeeded. | |
170 | */ | |
171 | static bool pcc_tx_done(struct mbox_chan *chan) | |
172 | { | |
173 | struct acpi_pcct_hw_reduced *pcct_ss = chan->con_priv; | |
174 | struct acpi_pcct_shared_memory *generic_comm_base = | |
175 | (struct acpi_pcct_shared_memory *) pcct_ss->base_address; | |
176 | u16 cmd_delay = pcct_ss->latency; | |
177 | unsigned int retries = 0; | |
178 | ||
179 | /* Try a few times while waiting for platform to consume */ | |
180 | while (!(readw_relaxed(&generic_comm_base->status) | |
181 | & PCC_CMD_COMPLETE)) { | |
182 | ||
183 | if (retries++ < 5) | |
184 | udelay(cmd_delay); | |
185 | else { | |
186 | /* | |
187 | * If the remote is dead, this will cause the Mbox | |
188 | * controller to timeout after mbox client.tx_tout | |
189 | * msecs. | |
190 | */ | |
191 | pr_err("PCC platform did not respond.\n"); | |
192 | return false; | |
193 | } | |
194 | } | |
195 | return true; | |
196 | } | |
197 | ||
198 | /** | |
199 | * pcc_send_data - Called from Mailbox Controller code to finally | |
200 | * transmit data over channel. | |
201 | * @chan: Pointer to Mailbox channel over which to send data. | |
202 | * @data: Actual data to be written over channel. | |
203 | * | |
204 | * Return: Err if something failed else 0 for success. | |
205 | */ | |
206 | static int pcc_send_data(struct mbox_chan *chan, void *data) | |
207 | { | |
208 | struct acpi_pcct_hw_reduced *pcct_ss = chan->con_priv; | |
209 | struct acpi_pcct_shared_memory *generic_comm_base = | |
210 | (struct acpi_pcct_shared_memory *) pcct_ss->base_address; | |
211 | struct acpi_generic_address doorbell; | |
212 | u64 doorbell_preserve; | |
213 | u64 doorbell_val; | |
214 | u64 doorbell_write; | |
215 | u16 cmd = *(u16 *) data; | |
216 | u16 ss_idx = -1; | |
217 | ||
218 | ss_idx = get_subspace_id(chan); | |
219 | ||
220 | if (ss_idx < 0) { | |
221 | pr_err("Invalid Subspace ID from PCC client\n"); | |
222 | return -EINVAL; | |
223 | } | |
224 | ||
225 | doorbell = pcct_ss->doorbell_register; | |
226 | doorbell_preserve = pcct_ss->preserve_mask; | |
227 | doorbell_write = pcct_ss->write_mask; | |
228 | ||
229 | /* Write to the shared comm region. */ | |
230 | writew(cmd, &generic_comm_base->command); | |
231 | ||
232 | /* Write Subspace MAGIC value so platform can identify destination. */ | |
233 | writel((PCCS_SS_SIG_MAGIC | ss_idx), &generic_comm_base->signature); | |
234 | ||
235 | /* Flip CMD COMPLETE bit */ | |
236 | writew(0, &generic_comm_base->status); | |
237 | ||
238 | /* Sync notification from OSPM to Platform. */ | |
239 | acpi_read(&doorbell_val, &doorbell); | |
240 | acpi_write((doorbell_val & doorbell_preserve) | doorbell_write, | |
241 | &doorbell); | |
242 | ||
243 | return 0; | |
244 | } | |
245 | ||
246 | static struct mbox_chan_ops pcc_chan_ops = { | |
247 | .send_data = pcc_send_data, | |
248 | .last_tx_done = pcc_tx_done, | |
249 | }; | |
250 | ||
251 | /** | |
252 | * parse_pcc_subspace - Parse the PCC table and verify PCC subspace | |
253 | * entries. There should be one entry per PCC client. | |
254 | * @header: Pointer to the ACPI subtable header under the PCCT. | |
255 | * @end: End of subtable entry. | |
256 | * | |
257 | * Return: 0 for Success, else errno. | |
258 | * | |
259 | * This gets called for each entry in the PCC table. | |
260 | */ | |
261 | static int parse_pcc_subspace(struct acpi_subtable_header *header, | |
262 | const unsigned long end) | |
263 | { | |
264 | struct acpi_pcct_hw_reduced *pcct_ss; | |
265 | ||
266 | if (pcc_mbox_ctrl.num_chans <= MAX_PCC_SUBSPACES) { | |
267 | pcct_ss = (struct acpi_pcct_hw_reduced *) header; | |
268 | ||
269 | if (pcct_ss->header.type != | |
270 | ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE) { | |
271 | pr_err("Incorrect PCC Subspace type detected\n"); | |
272 | return -EINVAL; | |
273 | } | |
274 | } | |
275 | ||
276 | return 0; | |
277 | } | |
278 | ||
279 | /** | |
280 | * acpi_pcc_probe - Parse the ACPI tree for the PCCT. | |
281 | * | |
282 | * Return: 0 for Success, else errno. | |
283 | */ | |
284 | static int __init acpi_pcc_probe(void) | |
285 | { | |
286 | acpi_size pcct_tbl_header_size; | |
287 | struct acpi_table_header *pcct_tbl; | |
288 | struct acpi_subtable_header *pcct_entry; | |
289 | int count, i; | |
290 | acpi_status status = AE_OK; | |
291 | ||
292 | /* Search for PCCT */ | |
293 | status = acpi_get_table_with_size(ACPI_SIG_PCCT, 0, | |
294 | &pcct_tbl, | |
295 | &pcct_tbl_header_size); | |
296 | ||
297 | if (ACPI_FAILURE(status) || !pcct_tbl) { | |
298 | pr_warn("PCCT header not found.\n"); | |
299 | return -ENODEV; | |
300 | } | |
301 | ||
302 | count = acpi_table_parse_entries(ACPI_SIG_PCCT, | |
303 | sizeof(struct acpi_table_pcct), | |
304 | ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE, | |
305 | parse_pcc_subspace, MAX_PCC_SUBSPACES); | |
306 | ||
307 | if (count <= 0) { | |
308 | pr_err("Error parsing PCC subspaces from PCCT\n"); | |
309 | return -EINVAL; | |
310 | } | |
311 | ||
312 | pcc_mbox_channels = kzalloc(sizeof(struct mbox_chan) * | |
313 | count, GFP_KERNEL); | |
314 | ||
315 | if (!pcc_mbox_channels) { | |
316 | pr_err("Could not allocate space for PCC mbox channels\n"); | |
317 | return -ENOMEM; | |
318 | } | |
319 | ||
320 | /* Point to the first PCC subspace entry */ | |
321 | pcct_entry = (struct acpi_subtable_header *) ( | |
322 | (unsigned long) pcct_tbl + sizeof(struct acpi_table_pcct)); | |
323 | ||
324 | for (i = 0; i < count; i++) { | |
325 | pcc_mbox_channels[i].con_priv = pcct_entry; | |
326 | pcct_entry = (struct acpi_subtable_header *) | |
327 | ((unsigned long) pcct_entry + pcct_entry->length); | |
328 | } | |
329 | ||
330 | pcc_mbox_ctrl.num_chans = count; | |
331 | ||
332 | pr_info("Detected %d PCC Subspaces\n", pcc_mbox_ctrl.num_chans); | |
333 | ||
334 | return 0; | |
335 | } | |
336 | ||
337 | /** | |
338 | * pcc_mbox_probe - Called when we find a match for the | |
339 | * PCCT platform device. This is purely used to represent | |
340 | * the PCCT as a virtual device for registering with the | |
341 | * generic Mailbox framework. | |
342 | * | |
343 | * @pdev: Pointer to platform device returned when a match | |
344 | * is found. | |
345 | * | |
346 | * Return: 0 for Success, else errno. | |
347 | */ | |
348 | static int pcc_mbox_probe(struct platform_device *pdev) | |
349 | { | |
350 | int ret = 0; | |
351 | ||
352 | pcc_mbox_ctrl.chans = pcc_mbox_channels; | |
353 | pcc_mbox_ctrl.ops = &pcc_chan_ops; | |
354 | pcc_mbox_ctrl.txdone_poll = true; | |
355 | pcc_mbox_ctrl.txpoll_period = 10; | |
356 | pcc_mbox_ctrl.dev = &pdev->dev; | |
357 | ||
358 | pr_info("Registering PCC driver as Mailbox controller\n"); | |
359 | ret = mbox_controller_register(&pcc_mbox_ctrl); | |
360 | ||
361 | if (ret) { | |
362 | pr_err("Err registering PCC as Mailbox controller: %d\n", ret); | |
363 | ret = -ENODEV; | |
364 | } | |
365 | ||
366 | return ret; | |
367 | } | |
368 | ||
369 | struct platform_driver pcc_mbox_driver = { | |
370 | .probe = pcc_mbox_probe, | |
371 | .driver = { | |
372 | .name = "PCCT", | |
373 | .owner = THIS_MODULE, | |
374 | }, | |
375 | }; | |
376 | ||
377 | static int __init pcc_init(void) | |
378 | { | |
379 | int ret; | |
380 | struct platform_device *pcc_pdev; | |
381 | ||
382 | if (acpi_disabled) | |
383 | return -ENODEV; | |
384 | ||
385 | /* Check if PCC support is available. */ | |
386 | ret = acpi_pcc_probe(); | |
387 | ||
388 | if (ret) { | |
389 | pr_err("ACPI PCC probe failed.\n"); | |
390 | return -ENODEV; | |
391 | } | |
392 | ||
393 | pcc_pdev = platform_create_bundle(&pcc_mbox_driver, | |
394 | pcc_mbox_probe, NULL, 0, NULL, 0); | |
395 | ||
396 | if (!pcc_pdev) { | |
397 | pr_err("Err creating PCC platform bundle\n"); | |
398 | return -ENODEV; | |
399 | } | |
400 | ||
401 | return 0; | |
402 | } | |
403 | device_initcall(pcc_init); |