[linux-2.6-block.git] / drivers / mailbox / pcc.c

/*
 *	Copyright (C) 2014 Linaro Ltd.
 *	Author:	Ashwin Chaugule <ashwin.chaugule@linaro.org>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  PCC (Platform Communication Channel) is defined in the ACPI 5.0+
 *  specification. It is a mailbox like mechanism to allow clients
 *  such as CPPC (Collaborative Processor Performance Control), RAS
 *  (Reliability, Availability and Serviceability) and MPST (Memory
 *  Node Power State Table) to talk to the platform (e.g. BMC) through
 *  shared memory regions as defined in the PCC table entries. The PCC
 *  specification supports a Doorbell mechanism for the PCC clients
 *  to notify the platform about new data. This Doorbell information
 *  is also specified in each PCC table entry. See pcc_send_data()
 *  and pcc_tx_done() for basic mode of operation.
 *
 *  For more details about PCC, please see the ACPI specification from
 *  http://www.uefi.org/ACPIv5.1 Section 14.
 *
 *  This file implements PCC as a Mailbox controller and allows for PCC
 *  clients to be implemented as its Mailbox Client Channels.
 */

#include <linux/acpi.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/platform_device.h>
#include <linux/mailbox_controller.h>
#include <linux/mailbox_client.h>

#include "mailbox.h"

#define MAX_PCC_SUBSPACES	256
#define PCCS_SS_SIG_MAGIC	0x50434300
#define PCC_CMD_COMPLETE	0x1

static struct mbox_chan *pcc_mbox_channels;

static struct mbox_controller pcc_mbox_ctrl = {};
/**
 * get_pcc_channel - Given a PCC subspace idx, get
 *	the respective mbox_channel.
 * @id: PCC subspace index.
 *
 * Return: ERR_PTR(errno) if error, else pointer
 *	to mbox channel.
 */
static struct mbox_chan *get_pcc_channel(int id)
{
	struct mbox_chan *pcc_chan;

	if (id < 0 || id > pcc_mbox_ctrl.num_chans)
		return ERR_PTR(-ENOENT);

	pcc_chan = (struct mbox_chan *)
		(unsigned long) pcc_mbox_channels +
		(id * sizeof(*pcc_chan));

	return pcc_chan;
}

/**
 * get_subspace_id - Given a Mailbox channel, find out the
 *		PCC subspace id.
 * @chan: Pointer to Mailbox Channel from which we want
 *		the index.
 * Return: Errno if not found, else positive index number.
 */
static int get_subspace_id(struct mbox_chan *chan)
{
	unsigned int id = chan - pcc_mbox_channels;

	if (id < 0 || id > pcc_mbox_ctrl.num_chans)
		return -ENOENT;

	return id;
}

/**
 * pcc_mbox_request_channel - PCC clients call this function to
 *		request a pointer to their PCC subspace, from which they
 *		can get the details of communicating with the remote.
 * @cl: Pointer to Mailbox client, so we know where to bind the
 *		Channel.
 * @subspace_id: The PCC Subspace index as parsed in the PCC client
 *		ACPI package. This is used to lookup the array of PCC
 *		subspaces as parsed by the PCC Mailbox controller.
 *
 * Return: Pointer to the Mailbox Channel if successful or
 *		ERR_PTR.
 */
struct mbox_chan *pcc_mbox_request_channel(struct mbox_client *cl,
		int subspace_id)
{
	struct device *dev = pcc_mbox_ctrl.dev;
	struct mbox_chan *chan;
	unsigned long flags;

	/*
	 * Each PCC Subspace is a Mailbox Channel.
	 * The PCC Clients get their PCC Subspace ID
	 * from their own tables and pass it here.
	 * This returns a pointer to the PCC subspace
	 * for the Client to operate on.
	 */
	chan = get_pcc_channel(subspace_id);

	if (!chan || chan->cl) {
		dev_err(dev, "%s: PCC mailbox not free\n", __func__);
		return ERR_PTR(-EBUSY);
	}

	spin_lock_irqsave(&chan->lock, flags);
	chan->msg_free = 0;
	chan->msg_count = 0;
	chan->active_req = NULL;
	chan->cl = cl;
	init_completion(&chan->tx_complete);

	if (chan->txdone_method == TXDONE_BY_POLL && cl->knows_txdone)
		chan->txdone_method |= TXDONE_BY_ACK;

	spin_unlock_irqrestore(&chan->lock, flags);

	return chan;
}
EXPORT_SYMBOL_GPL(pcc_mbox_request_channel);

/**
 * pcc_mbox_free_channel - Clients call this to free their Channel.
 *
 * @chan: Pointer to the mailbox channel as returned by
 *		pcc_mbox_request_channel()
 */
void pcc_mbox_free_channel(struct mbox_chan *chan)
{
	unsigned long flags;

	if (!chan || !chan->cl)
		return;

	spin_lock_irqsave(&chan->lock, flags);
	chan->cl = NULL;
	chan->active_req = NULL;
	if (chan->txdone_method == (TXDONE_BY_POLL | TXDONE_BY_ACK))
		chan->txdone_method = TXDONE_BY_POLL;

	spin_unlock_irqrestore(&chan->lock, flags);
}
EXPORT_SYMBOL_GPL(pcc_mbox_free_channel);

/**
 * pcc_tx_done - Callback from Mailbox controller code to
 *		check if PCC message transmission completed.
 * @chan: Pointer to Mailbox channel on which previous
 *		transmission occurred.
 *
 * Return: TRUE if succeeded.
 */
static bool pcc_tx_done(struct mbox_chan *chan)
{
	struct acpi_pcct_hw_reduced *pcct_ss = chan->con_priv;
	struct acpi_pcct_shared_memory *generic_comm_base =
		(struct acpi_pcct_shared_memory *) pcct_ss->base_address;
	u16 cmd_delay = pcct_ss->latency;
	unsigned int retries = 0;

	/* Try a few times while waiting for platform to consume */
	while (!(readw_relaxed(&generic_comm_base->status)
		    & PCC_CMD_COMPLETE)) {

		if (retries++ < 5)
			udelay(cmd_delay);
		else {
			/*
			 * If the remote is dead, this will cause the Mbox
			 * controller to timeout after mbox client.tx_tout
			 * msecs.
			 */
			pr_err("PCC platform did not respond.\n");
			return false;
		}
	}
	return true;
}

/**
 * pcc_send_data - Called from Mailbox Controller code to finally
 *	transmit data over channel.
 * @chan: Pointer to Mailbox channel over which to send data.
 * @data: Actual data to be written over channel.
 *
 * Return: Err if something failed else 0 for success.
 */
static int pcc_send_data(struct mbox_chan *chan, void *data)
{
	struct acpi_pcct_hw_reduced *pcct_ss = chan->con_priv;
	struct acpi_pcct_shared_memory *generic_comm_base =
		(struct acpi_pcct_shared_memory *) pcct_ss->base_address;
	struct acpi_generic_address doorbell;
	u64 doorbell_preserve;
	u64 doorbell_val;
	u64 doorbell_write;
	u16 cmd = *(u16 *) data;
	u16 ss_idx = -1;

	ss_idx = get_subspace_id(chan);

	if (ss_idx < 0) {
		pr_err("Invalid Subspace ID from PCC client\n");
		return -EINVAL;
	}

	doorbell = pcct_ss->doorbell_register;
	doorbell_preserve = pcct_ss->preserve_mask;
	doorbell_write = pcct_ss->write_mask;

	/* Write to the shared comm region. */
	writew(cmd, &generic_comm_base->command);

	/* Write Subspace MAGIC value so platform can identify destination. */
	writel((PCCS_SS_SIG_MAGIC | ss_idx), &generic_comm_base->signature);

	/* Flip CMD COMPLETE bit */
	writew(0, &generic_comm_base->status);

	/* Sync notification from OSPM to Platform. */
	acpi_read(&doorbell_val, &doorbell);
	acpi_write((doorbell_val & doorbell_preserve) | doorbell_write,
			&doorbell);

	return 0;
}

static struct mbox_chan_ops pcc_chan_ops = {
	.send_data = pcc_send_data,
	.last_tx_done = pcc_tx_done,
};

/**
 * parse_pcc_subspace - Parse the PCC table and verify PCC subspace
 *		entries. There should be one entry per PCC client.
 * @header: Pointer to the ACPI subtable header under the PCCT.
 * @end: End of subtable entry.
 *
 * Return: 0 for Success, else errno.
 *
 * This gets called for each entry in the PCC table.
 */
static int parse_pcc_subspace(struct acpi_subtable_header *header,
		const unsigned long end)
{
	struct acpi_pcct_hw_reduced *pcct_ss;

	if (pcc_mbox_ctrl.num_chans <= MAX_PCC_SUBSPACES) {
		pcct_ss = (struct acpi_pcct_hw_reduced *) header;

		if (pcct_ss->header.type !=
				ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE) {
			pr_err("Incorrect PCC Subspace type detected\n");
			return -EINVAL;
		}
	}

	return 0;
}

/**
 * acpi_pcc_probe - Parse the ACPI tree for the PCCT.
 *
 * Return: 0 for Success, else errno.
 */
static int __init acpi_pcc_probe(void)
{
	acpi_size pcct_tbl_header_size;
	struct acpi_table_header *pcct_tbl;
	struct acpi_subtable_header *pcct_entry;
	int count, i;
	acpi_status status = AE_OK;

	/* Search for PCCT */
	status = acpi_get_table_with_size(ACPI_SIG_PCCT, 0,
			&pcct_tbl,
			&pcct_tbl_header_size);

	if (ACPI_FAILURE(status) || !pcct_tbl) {
		pr_warn("PCCT header not found.\n");
		return -ENODEV;
	}

	count = acpi_table_parse_entries(ACPI_SIG_PCCT,
			sizeof(struct acpi_table_pcct),
			ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE,
			parse_pcc_subspace, MAX_PCC_SUBSPACES);

	if (count <= 0) {
		pr_err("Error parsing PCC subspaces from PCCT\n");
		return -EINVAL;
	}

	pcc_mbox_channels = kzalloc(sizeof(struct mbox_chan) *
			count, GFP_KERNEL);

	if (!pcc_mbox_channels) {
		pr_err("Could not allocate space for PCC mbox channels\n");
		return -ENOMEM;
	}

	/* Point to the first PCC subspace entry */
	pcct_entry = (struct acpi_subtable_header *) (
		(unsigned long) pcct_tbl + sizeof(struct acpi_table_pcct));

	for (i = 0; i < count; i++) {
		pcc_mbox_channels[i].con_priv = pcct_entry;
		pcct_entry = (struct acpi_subtable_header *)
			((unsigned long) pcct_entry + pcct_entry->length);
	}

	pcc_mbox_ctrl.num_chans = count;

	pr_info("Detected %d PCC Subspaces\n", pcc_mbox_ctrl.num_chans);

	return 0;
}

/**
 * pcc_mbox_probe - Called when we find a match for the
 *	PCCT platform device. This is purely used to represent
 *	the PCCT as a virtual device for registering with the
 *	generic Mailbox framework.
 *
 * @pdev: Pointer to platform device returned when a match
 *	is found.
 *
 *	Return: 0 for Success, else errno.
 */
static int pcc_mbox_probe(struct platform_device *pdev)
{
	int ret = 0;

	pcc_mbox_ctrl.chans = pcc_mbox_channels;
	pcc_mbox_ctrl.ops = &pcc_chan_ops;
	pcc_mbox_ctrl.txdone_poll = true;
	pcc_mbox_ctrl.txpoll_period = 10;
	pcc_mbox_ctrl.dev = &pdev->dev;

	pr_info("Registering PCC driver as Mailbox controller\n");
	ret = mbox_controller_register(&pcc_mbox_ctrl);

	if (ret) {
		pr_err("Err registering PCC as Mailbox controller: %d\n", ret);
		ret = -ENODEV;
	}

	return ret;
}

struct platform_driver pcc_mbox_driver = {
	.probe = pcc_mbox_probe,
	.driver = {
		.name = "PCCT",
		.owner = THIS_MODULE,
	},
};

static int __init pcc_init(void)
{
	int ret;
	struct platform_device *pcc_pdev;

	if (acpi_disabled)
		return -ENODEV;

	/* Check if PCC support is available. */
	ret = acpi_pcc_probe();

	if (ret) {
		pr_err("ACPI PCC probe failed.\n");
		return -ENODEV;
	}

	pcc_pdev = platform_create_bundle(&pcc_mbox_driver,
			pcc_mbox_probe, NULL, 0, NULL, 0);

	if (!pcc_pdev) {
		pr_err("Err creating PCC platform bundle\n");
		return -ENODEV;
	}

	return 0;
}
device_initcall(pcc_init);
Commit	Line	Data
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
	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);