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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
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
48static struct mbox_chan *pcc_mbox_channels;
49
50static 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 */
59static 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 */
80static 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 */
103struct 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}
138EXPORT_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 */
146void 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}
161EXPORT_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 */
171static 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 */
206static 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
246static 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 */
261static 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 */
284static 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 */
348static 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
369struct platform_driver pcc_mbox_driver = {
370 .probe = pcc_mbox_probe,
371 .driver = {
372 .name = "PCCT",
373 .owner = THIS_MODULE,
374 },
375};
376
377static 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) {
Rafael J. Wysockiefd756d2015-02-05 00:40:08 +0100389 pr_debug("ACPI PCC probe failed.\n");
Ashwin Chaugule86c22f82014-11-12 19:59:38 -0500390 return -ENODEV;
391 }
392
393 pcc_pdev = platform_create_bundle(&pcc_mbox_driver,
394 pcc_mbox_probe, NULL, 0, NULL, 0);
395
Wei Yongjun356d5d22015-01-14 09:10:56 +0800396 if (IS_ERR(pcc_pdev)) {
Rafael J. Wysockiefd756d2015-02-05 00:40:08 +0100397 pr_debug("Err creating PCC platform bundle\n");
Wei Yongjun356d5d22015-01-14 09:10:56 +0800398 return PTR_ERR(pcc_pdev);
Ashwin Chaugule86c22f82014-11-12 19:59:38 -0500399 }
400
401 return 0;
402}
403device_initcall(pcc_init);