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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> | |
66 | ||
67 | #include "mailbox.h" | |
68 | ||
69 | #define MAX_PCC_SUBSPACES 256 | |
86c22f8c AC |
70 | |
71 | static struct mbox_chan *pcc_mbox_channels; | |
72 | ||
73 | static struct mbox_controller pcc_mbox_ctrl = {}; | |
74 | /** | |
75 | * get_pcc_channel - Given a PCC subspace idx, get | |
76 | * the respective mbox_channel. | |
77 | * @id: PCC subspace index. | |
78 | * | |
79 | * Return: ERR_PTR(errno) if error, else pointer | |
80 | * to mbox channel. | |
81 | */ | |
82 | static struct mbox_chan *get_pcc_channel(int id) | |
83 | { | |
84 | struct mbox_chan *pcc_chan; | |
85 | ||
86 | if (id < 0 || id > pcc_mbox_ctrl.num_chans) | |
87 | return ERR_PTR(-ENOENT); | |
88 | ||
89 | pcc_chan = (struct mbox_chan *) | |
90 | (unsigned long) pcc_mbox_channels + | |
91 | (id * sizeof(*pcc_chan)); | |
92 | ||
93 | return pcc_chan; | |
94 | } | |
95 | ||
86c22f8c AC |
96 | /** |
97 | * pcc_mbox_request_channel - PCC clients call this function to | |
98 | * request a pointer to their PCC subspace, from which they | |
99 | * can get the details of communicating with the remote. | |
100 | * @cl: Pointer to Mailbox client, so we know where to bind the | |
101 | * Channel. | |
102 | * @subspace_id: The PCC Subspace index as parsed in the PCC client | |
103 | * ACPI package. This is used to lookup the array of PCC | |
104 | * subspaces as parsed by the PCC Mailbox controller. | |
105 | * | |
106 | * Return: Pointer to the Mailbox Channel if successful or | |
107 | * ERR_PTR. | |
108 | */ | |
109 | struct mbox_chan *pcc_mbox_request_channel(struct mbox_client *cl, | |
110 | int subspace_id) | |
111 | { | |
112 | struct device *dev = pcc_mbox_ctrl.dev; | |
113 | struct mbox_chan *chan; | |
114 | unsigned long flags; | |
115 | ||
116 | /* | |
117 | * Each PCC Subspace is a Mailbox Channel. | |
118 | * The PCC Clients get their PCC Subspace ID | |
119 | * from their own tables and pass it here. | |
120 | * This returns a pointer to the PCC subspace | |
121 | * for the Client to operate on. | |
122 | */ | |
123 | chan = get_pcc_channel(subspace_id); | |
124 | ||
d311a28a | 125 | if (IS_ERR(chan) || chan->cl) { |
33350e6b | 126 | dev_err(dev, "Channel not found for idx: %d\n", subspace_id); |
86c22f8c AC |
127 | return ERR_PTR(-EBUSY); |
128 | } | |
129 | ||
130 | spin_lock_irqsave(&chan->lock, flags); | |
131 | chan->msg_free = 0; | |
132 | chan->msg_count = 0; | |
133 | chan->active_req = NULL; | |
134 | chan->cl = cl; | |
135 | init_completion(&chan->tx_complete); | |
136 | ||
137 | if (chan->txdone_method == TXDONE_BY_POLL && cl->knows_txdone) | |
138 | chan->txdone_method |= TXDONE_BY_ACK; | |
139 | ||
140 | spin_unlock_irqrestore(&chan->lock, flags); | |
141 | ||
142 | return chan; | |
143 | } | |
144 | EXPORT_SYMBOL_GPL(pcc_mbox_request_channel); | |
145 | ||
146 | /** | |
147 | * pcc_mbox_free_channel - Clients call this to free their Channel. | |
148 | * | |
149 | * @chan: Pointer to the mailbox channel as returned by | |
150 | * pcc_mbox_request_channel() | |
151 | */ | |
152 | void pcc_mbox_free_channel(struct mbox_chan *chan) | |
153 | { | |
154 | unsigned long flags; | |
155 | ||
156 | if (!chan || !chan->cl) | |
157 | return; | |
158 | ||
159 | spin_lock_irqsave(&chan->lock, flags); | |
160 | chan->cl = NULL; | |
161 | chan->active_req = NULL; | |
162 | if (chan->txdone_method == (TXDONE_BY_POLL | TXDONE_BY_ACK)) | |
163 | chan->txdone_method = TXDONE_BY_POLL; | |
164 | ||
165 | spin_unlock_irqrestore(&chan->lock, flags); | |
166 | } | |
167 | EXPORT_SYMBOL_GPL(pcc_mbox_free_channel); | |
168 | ||
169 | /** | |
33350e6b AC |
170 | * pcc_send_data - Called from Mailbox Controller code. Used |
171 | * here only to ring the channel doorbell. The PCC client | |
172 | * specific read/write is done in the client driver in | |
173 | * order to maintain atomicity over PCC channel once | |
174 | * OS has control over it. See above for flow of operations. | |
86c22f8c | 175 | * @chan: Pointer to Mailbox channel over which to send data. |
33350e6b AC |
176 | * @data: Client specific data written over channel. Used here |
177 | * only for debug after PCC transaction completes. | |
86c22f8c AC |
178 | * |
179 | * Return: Err if something failed else 0 for success. | |
180 | */ | |
181 | static int pcc_send_data(struct mbox_chan *chan, void *data) | |
182 | { | |
183 | struct acpi_pcct_hw_reduced *pcct_ss = chan->con_priv; | |
86c22f8c AC |
184 | struct acpi_generic_address doorbell; |
185 | u64 doorbell_preserve; | |
186 | u64 doorbell_val; | |
187 | u64 doorbell_write; | |
86c22f8c AC |
188 | |
189 | doorbell = pcct_ss->doorbell_register; | |
190 | doorbell_preserve = pcct_ss->preserve_mask; | |
191 | doorbell_write = pcct_ss->write_mask; | |
192 | ||
33350e6b | 193 | /* Sync notification from OS to Platform. */ |
86c22f8c AC |
194 | acpi_read(&doorbell_val, &doorbell); |
195 | acpi_write((doorbell_val & doorbell_preserve) | doorbell_write, | |
196 | &doorbell); | |
197 | ||
198 | return 0; | |
199 | } | |
200 | ||
05ae7975 | 201 | static const struct mbox_chan_ops pcc_chan_ops = { |
86c22f8c | 202 | .send_data = pcc_send_data, |
86c22f8c AC |
203 | }; |
204 | ||
205 | /** | |
206 | * parse_pcc_subspace - Parse the PCC table and verify PCC subspace | |
207 | * entries. There should be one entry per PCC client. | |
208 | * @header: Pointer to the ACPI subtable header under the PCCT. | |
209 | * @end: End of subtable entry. | |
210 | * | |
211 | * Return: 0 for Success, else errno. | |
212 | * | |
213 | * This gets called for each entry in the PCC table. | |
214 | */ | |
215 | static int parse_pcc_subspace(struct acpi_subtable_header *header, | |
216 | const unsigned long end) | |
217 | { | |
218 | struct acpi_pcct_hw_reduced *pcct_ss; | |
219 | ||
220 | if (pcc_mbox_ctrl.num_chans <= MAX_PCC_SUBSPACES) { | |
221 | pcct_ss = (struct acpi_pcct_hw_reduced *) header; | |
222 | ||
223 | if (pcct_ss->header.type != | |
224 | ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE) { | |
225 | pr_err("Incorrect PCC Subspace type detected\n"); | |
226 | return -EINVAL; | |
227 | } | |
228 | } | |
229 | ||
230 | return 0; | |
231 | } | |
232 | ||
233 | /** | |
234 | * acpi_pcc_probe - Parse the ACPI tree for the PCCT. | |
235 | * | |
236 | * Return: 0 for Success, else errno. | |
237 | */ | |
238 | static int __init acpi_pcc_probe(void) | |
239 | { | |
240 | acpi_size pcct_tbl_header_size; | |
241 | struct acpi_table_header *pcct_tbl; | |
242 | struct acpi_subtable_header *pcct_entry; | |
243 | int count, i; | |
244 | acpi_status status = AE_OK; | |
245 | ||
246 | /* Search for PCCT */ | |
247 | status = acpi_get_table_with_size(ACPI_SIG_PCCT, 0, | |
248 | &pcct_tbl, | |
249 | &pcct_tbl_header_size); | |
250 | ||
251 | if (ACPI_FAILURE(status) || !pcct_tbl) { | |
252 | pr_warn("PCCT header not found.\n"); | |
253 | return -ENODEV; | |
254 | } | |
255 | ||
256 | count = acpi_table_parse_entries(ACPI_SIG_PCCT, | |
257 | sizeof(struct acpi_table_pcct), | |
258 | ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE, | |
259 | parse_pcc_subspace, MAX_PCC_SUBSPACES); | |
260 | ||
261 | if (count <= 0) { | |
262 | pr_err("Error parsing PCC subspaces from PCCT\n"); | |
263 | return -EINVAL; | |
264 | } | |
265 | ||
266 | pcc_mbox_channels = kzalloc(sizeof(struct mbox_chan) * | |
267 | count, GFP_KERNEL); | |
268 | ||
269 | if (!pcc_mbox_channels) { | |
270 | pr_err("Could not allocate space for PCC mbox channels\n"); | |
271 | return -ENOMEM; | |
272 | } | |
273 | ||
274 | /* Point to the first PCC subspace entry */ | |
275 | pcct_entry = (struct acpi_subtable_header *) ( | |
276 | (unsigned long) pcct_tbl + sizeof(struct acpi_table_pcct)); | |
277 | ||
278 | for (i = 0; i < count; i++) { | |
279 | pcc_mbox_channels[i].con_priv = pcct_entry; | |
280 | pcct_entry = (struct acpi_subtable_header *) | |
281 | ((unsigned long) pcct_entry + pcct_entry->length); | |
282 | } | |
283 | ||
284 | pcc_mbox_ctrl.num_chans = count; | |
285 | ||
286 | pr_info("Detected %d PCC Subspaces\n", pcc_mbox_ctrl.num_chans); | |
287 | ||
288 | return 0; | |
289 | } | |
290 | ||
291 | /** | |
292 | * pcc_mbox_probe - Called when we find a match for the | |
293 | * PCCT platform device. This is purely used to represent | |
294 | * the PCCT as a virtual device for registering with the | |
295 | * generic Mailbox framework. | |
296 | * | |
297 | * @pdev: Pointer to platform device returned when a match | |
298 | * is found. | |
299 | * | |
300 | * Return: 0 for Success, else errno. | |
301 | */ | |
302 | static int pcc_mbox_probe(struct platform_device *pdev) | |
303 | { | |
304 | int ret = 0; | |
305 | ||
306 | pcc_mbox_ctrl.chans = pcc_mbox_channels; | |
307 | pcc_mbox_ctrl.ops = &pcc_chan_ops; | |
86c22f8c AC |
308 | pcc_mbox_ctrl.dev = &pdev->dev; |
309 | ||
310 | pr_info("Registering PCC driver as Mailbox controller\n"); | |
311 | ret = mbox_controller_register(&pcc_mbox_ctrl); | |
312 | ||
313 | if (ret) { | |
314 | pr_err("Err registering PCC as Mailbox controller: %d\n", ret); | |
315 | ret = -ENODEV; | |
316 | } | |
317 | ||
318 | return ret; | |
319 | } | |
320 | ||
321 | struct platform_driver pcc_mbox_driver = { | |
322 | .probe = pcc_mbox_probe, | |
323 | .driver = { | |
324 | .name = "PCCT", | |
325 | .owner = THIS_MODULE, | |
326 | }, | |
327 | }; | |
328 | ||
329 | static int __init pcc_init(void) | |
330 | { | |
331 | int ret; | |
332 | struct platform_device *pcc_pdev; | |
333 | ||
334 | if (acpi_disabled) | |
335 | return -ENODEV; | |
336 | ||
337 | /* Check if PCC support is available. */ | |
338 | ret = acpi_pcc_probe(); | |
339 | ||
340 | if (ret) { | |
efd756da | 341 | pr_debug("ACPI PCC probe failed.\n"); |
86c22f8c AC |
342 | return -ENODEV; |
343 | } | |
344 | ||
345 | pcc_pdev = platform_create_bundle(&pcc_mbox_driver, | |
346 | pcc_mbox_probe, NULL, 0, NULL, 0); | |
347 | ||
356d5d28 | 348 | if (IS_ERR(pcc_pdev)) { |
efd756da | 349 | pr_debug("Err creating PCC platform bundle\n"); |
356d5d28 | 350 | return PTR_ERR(pcc_pdev); |
86c22f8c AC |
351 | } |
352 | ||
353 | return 0; | |
354 | } | |
d3c68f21 AC |
355 | |
356 | /* | |
357 | * Make PCC init postcore so that users of this mailbox | |
358 | * such as the ACPI Processor driver have it available | |
359 | * at their init. | |
360 | */ | |
361 | postcore_initcall(pcc_init); |