blob: 26d121d1d501b7617857a364a63c9dd4b97c1438 [file] [log] [blame]
Ashwin Chaugule86c22f82014-11-12 19:59:38 -05001/*
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
Ashwin Chaugule33350e62015-01-27 16:03:57 -050023 * is also specified in each PCC table entry.
Ashwin Chaugule86c22f82014-11-12 19:59:38 -050024 *
Ashwin Chaugule33350e62015-01-27 16:03:57 -050025 * 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
Ashwin Chaugule86c22f82014-11-12 19:59:38 -050052 * 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
Ashwin Chaugule86c22f82014-11-12 19:59:38 -050070
71static struct mbox_chan *pcc_mbox_channels;
72
73static 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 */
82static 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
96/**
Ashwin Chaugule86c22f82014-11-12 19:59:38 -050097 * 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 */
109struct 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
125 if (!chan || chan->cl) {
Ashwin Chaugule33350e62015-01-27 16:03:57 -0500126 dev_err(dev, "Channel not found for idx: %d\n", subspace_id);
Ashwin Chaugule86c22f82014-11-12 19:59:38 -0500127 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}
144EXPORT_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 */
152void 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}
167EXPORT_SYMBOL_GPL(pcc_mbox_free_channel);
168
169/**
Ashwin Chaugule33350e62015-01-27 16:03:57 -0500170 * 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.
Ashwin Chaugule86c22f82014-11-12 19:59:38 -0500175 * @chan: Pointer to Mailbox channel over which to send data.
Ashwin Chaugule33350e62015-01-27 16:03:57 -0500176 * @data: Client specific data written over channel. Used here
177 * only for debug after PCC transaction completes.
Ashwin Chaugule86c22f82014-11-12 19:59:38 -0500178 *
179 * Return: Err if something failed else 0 for success.
180 */
181static int pcc_send_data(struct mbox_chan *chan, void *data)
182{
183 struct acpi_pcct_hw_reduced *pcct_ss = chan->con_priv;
Ashwin Chaugule86c22f82014-11-12 19:59:38 -0500184 struct acpi_generic_address doorbell;
185 u64 doorbell_preserve;
186 u64 doorbell_val;
187 u64 doorbell_write;
Ashwin Chaugule86c22f82014-11-12 19:59:38 -0500188
189 doorbell = pcct_ss->doorbell_register;
190 doorbell_preserve = pcct_ss->preserve_mask;
191 doorbell_write = pcct_ss->write_mask;
192
Ashwin Chaugule33350e62015-01-27 16:03:57 -0500193 /* Sync notification from OS to Platform. */
Ashwin Chaugule86c22f82014-11-12 19:59:38 -0500194 acpi_read(&doorbell_val, &doorbell);
195 acpi_write((doorbell_val & doorbell_preserve) | doorbell_write,
196 &doorbell);
197
198 return 0;
199}
200
Andrew Bresticker05ae7972015-05-04 10:36:35 -0700201static const struct mbox_chan_ops pcc_chan_ops = {
Ashwin Chaugule86c22f82014-11-12 19:59:38 -0500202 .send_data = pcc_send_data,
Ashwin Chaugule86c22f82014-11-12 19:59:38 -0500203};
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 */
215static 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 */
238static 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 */
302static 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;
Ashwin Chaugule86c22f82014-11-12 19:59:38 -0500308 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
321struct platform_driver pcc_mbox_driver = {
322 .probe = pcc_mbox_probe,
323 .driver = {
324 .name = "PCCT",
325 .owner = THIS_MODULE,
326 },
327};
328
329static 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) {
Rafael J. Wysockiefd756d2015-02-05 00:40:08 +0100341 pr_debug("ACPI PCC probe failed.\n");
Ashwin Chaugule86c22f82014-11-12 19:59:38 -0500342 return -ENODEV;
343 }
344
345 pcc_pdev = platform_create_bundle(&pcc_mbox_driver,
346 pcc_mbox_probe, NULL, 0, NULL, 0);
347
Wei Yongjun356d5d22015-01-14 09:10:56 +0800348 if (IS_ERR(pcc_pdev)) {
Rafael J. Wysockiefd756d2015-02-05 00:40:08 +0100349 pr_debug("Err creating PCC platform bundle\n");
Wei Yongjun356d5d22015-01-14 09:10:56 +0800350 return PTR_ERR(pcc_pdev);
Ashwin Chaugule86c22f82014-11-12 19:59:38 -0500351 }
352
353 return 0;
354}
355device_initcall(pcc_init);