[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.
 *
 *  Typical high level flow of operation is:
 *
 *  PCC Reads:
 *  * Client tries to acquire a channel lock.
 *  * After it is acquired it writes READ cmd in communication region cmd
 *		address.
 *  * Client issues mbox_send_message() which rings the PCC doorbell
 *		for its PCC channel.
 *  * If command completes, then client has control over channel and
 *		it can proceed with its reads.
 *  * Client releases lock.
 *
 *  PCC Writes:
 *  * Client tries to acquire channel lock.
 *  * Client writes to its communication region after it acquires a
 *		channel lock.
 *  * Client writes WRITE cmd in communication region cmd address.
 *  * Client issues mbox_send_message() which rings the PCC doorbell
 *		for its PCC channel.
 *  * If command completes, then writes have succeded and it can release
 *		the channel lock.
 *
 *  There is a Nominal latency defined for each channel which indicates
 *  how long to wait until a command completes. If command is not complete
 *  the client needs to retry or assume failure.
 *
 *	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 <linux/io-64-nonatomic-lo-hi.h>

#include "mailbox.h"

#define MAX_PCC_SUBSPACES	256

static struct mbox_chan *pcc_mbox_channels;

/* Array of cached virtual address for doorbell registers */
static void __iomem **pcc_doorbell_vaddr;

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

	return &pcc_mbox_channels[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 (IS_ERR(chan) || chan->cl) {
		dev_err(dev, "Channel not found for idx: %d\n", subspace_id);
		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 can be used with perf critical drivers such as CPPC
 * So it makes sense to locally cache the virtual address and
 * use it to read/write to PCC registers such as doorbell register
 *
 * The below read_register and write_registers are used to read and
 * write from perf critical registers such as PCC doorbell register
 */
static int read_register(void __iomem *vaddr, u64 *val, unsigned int bit_width)
{
	int ret_val = 0;

	switch (bit_width) {
	case 8:
		*val = readb(vaddr);
		break;
	case 16:
		*val = readw(vaddr);
		break;
	case 32:
		*val = readl(vaddr);
		break;
	case 64:
		*val = readq(vaddr);
		break;
	default:
		pr_debug("Error: Cannot read register of %u bit width",
			bit_width);
		ret_val = -EFAULT;
		break;
	}
	return ret_val;
}

static int write_register(void __iomem *vaddr, u64 val, unsigned int bit_width)
{
	int ret_val = 0;

	switch (bit_width) {
	case 8:
		writeb(val, vaddr);
		break;
	case 16:
		writew(val, vaddr);
		break;
	case 32:
		writel(val, vaddr);
		break;
	case 64:
		writeq(val, vaddr);
		break;
	default:
		pr_debug("Error: Cannot write register of %u bit width",
			bit_width);
		ret_val = -EFAULT;
		break;
	}
	return ret_val;
}

/**
 * pcc_send_data - Called from Mailbox Controller code. Used
 *		here only to ring the channel doorbell. The PCC client
 *		specific read/write is done in the client driver in
 *		order to maintain atomicity over PCC channel once
 *		OS has control over it. See above for flow of operations.
 * @chan: Pointer to Mailbox channel over which to send data.
 * @data: Client specific data written over channel. Used here
 *		only for debug after PCC transaction completes.
 *
 * 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_generic_address *doorbell;
	u64 doorbell_preserve;
	u64 doorbell_val;
	u64 doorbell_write;
	u32 id = chan - pcc_mbox_channels;
	int ret = 0;

	if (id >= pcc_mbox_ctrl.num_chans) {
		pr_debug("pcc_send_data: Invalid mbox_chan passed\n");
		return -ENOENT;
	}

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

	/* Sync notification from OS to Platform. */
	if (pcc_doorbell_vaddr[id]) {
		ret = read_register(pcc_doorbell_vaddr[id], &doorbell_val,
			doorbell->bit_width);
		if (ret)
			return ret;
		ret = write_register(pcc_doorbell_vaddr[id],
			(doorbell_val & doorbell_preserve) | doorbell_write,
			doorbell->bit_width);
	} else {
		ret = acpi_read(&doorbell_val, doorbell);
		if (ret)
			return ret;
		ret = acpi_write((doorbell_val & doorbell_preserve) | doorbell_write,
			doorbell);
	}
	return ret;
}

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

/**
 * 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;
	}

	pcc_doorbell_vaddr = kcalloc(count, sizeof(void *), GFP_KERNEL);
	if (!pcc_doorbell_vaddr) {
		kfree(pcc_mbox_channels);
		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++) {
		struct acpi_generic_address *db_reg;
		struct acpi_pcct_hw_reduced *pcct_ss;
		pcc_mbox_channels[i].con_priv = pcct_entry;

		/* If doorbell is in system memory cache the virt address */
		pcct_ss = (struct acpi_pcct_hw_reduced *)pcct_entry;
		db_reg = &pcct_ss->doorbell_register;
		if (db_reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
			pcc_doorbell_vaddr[i] = acpi_os_ioremap(db_reg->address,
							db_reg->bit_width/8);
		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.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_debug("ACPI PCC probe failed.\n");
		return -ENODEV;
	}

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

	if (IS_ERR(pcc_pdev)) {
		pr_debug("Err creating PCC platform bundle\n");
		return PTR_ERR(pcc_pdev);
	}

	return 0;
}

/*
 * Make PCC init postcore so that users of this mailbox
 * such as the ACPI Processor driver have it available
 * at their init.
 */
postcore_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
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>
8b0f5788	66	#include <linux/io-64-nonatomic-lo-hi.h>
86c22f8c AC	67
	68	#include "mailbox.h"
	69
	70	#define MAX_PCC_SUBSPACES 256
86c22f8c AC	71
	72	static struct mbox_chan *pcc_mbox_channels;
	73
8b0f5788 PP	74	/* Array of cached virtual address for doorbell registers */
	75	static void __iomem **pcc_doorbell_vaddr;
	76
86c22f8c AC	77	static struct mbox_controller pcc_mbox_ctrl = {};
	78	/**
	79	* get_pcc_channel - Given a PCC subspace idx, get
	80	* the respective mbox_channel.
	81	* @id: PCC subspace index.
	82	*
	83	* Return: ERR_PTR(errno) if error, else pointer
	84	* to mbox channel.
	85	*/
	86	static struct mbox_chan *get_pcc_channel(int id)
	87	{
86c22f8c AC	88	if (id < 0 \|\| id > pcc_mbox_ctrl.num_chans)
	89	return ERR_PTR(-ENOENT);
	90
e9c8dc8b	91	return &pcc_mbox_channels[id];
86c22f8c AC	92	}
86c22f8c AC	93
86c22f8c AC	94	/**
	95	* pcc_mbox_request_channel - PCC clients call this function to
	96	* request a pointer to their PCC subspace, from which they
	97	* can get the details of communicating with the remote.
	98	* @cl: Pointer to Mailbox client, so we know where to bind the
	99	* Channel.
	100	* @subspace_id: The PCC Subspace index as parsed in the PCC client
	101	* ACPI package. This is used to lookup the array of PCC
	102	* subspaces as parsed by the PCC Mailbox controller.
	103	*
	104	* Return: Pointer to the Mailbox Channel if successful or
	105	* ERR_PTR.
	106	*/
	107	struct mbox_chan pcc_mbox_request_channel(struct mbox_client cl,
	108	int subspace_id)
	109	{
	110	struct device *dev = pcc_mbox_ctrl.dev;
	111	struct mbox_chan *chan;
	112	unsigned long flags;
	113
	114	/*
	115	* Each PCC Subspace is a Mailbox Channel.
	116	* The PCC Clients get their PCC Subspace ID
	117	* from their own tables and pass it here.
	118	* This returns a pointer to the PCC subspace
	119	* for the Client to operate on.
	120	*/
	121	chan = get_pcc_channel(subspace_id);
	122
d311a28a	123	if (IS_ERR(chan) \|\| chan->cl) {
33350e6b	124	dev_err(dev, "Channel not found for idx: %d\n", subspace_id);
86c22f8c AC	125	return ERR_PTR(-EBUSY);
	126	}
	127
	128	spin_lock_irqsave(&chan->lock, flags);
	129	chan->msg_free = 0;
	130	chan->msg_count = 0;
	131	chan->active_req = NULL;
	132	chan->cl = cl;
	133	init_completion(&chan->tx_complete);
	134
	135	if (chan->txdone_method == TXDONE_BY_POLL && cl->knows_txdone)
	136	chan->txdone_method \|= TXDONE_BY_ACK;
	137
	138	spin_unlock_irqrestore(&chan->lock, flags);
	139
	140	return chan;
	141	}
	142	EXPORT_SYMBOL_GPL(pcc_mbox_request_channel);
	143
	144	/**
	145	* pcc_mbox_free_channel - Clients call this to free their Channel.
	146	*
	147	* @chan: Pointer to the mailbox channel as returned by
	148	* pcc_mbox_request_channel()
	149	*/
	150	void pcc_mbox_free_channel(struct mbox_chan *chan)
	151	{
	152	unsigned long flags;
	153
	154	if (!chan \|\| !chan->cl)
	155	return;
	156
	157	spin_lock_irqsave(&chan->lock, flags);
	158	chan->cl = NULL;
	159	chan->active_req = NULL;
	160	if (chan->txdone_method == (TXDONE_BY_POLL \| TXDONE_BY_ACK))
	161	chan->txdone_method = TXDONE_BY_POLL;
	162
	163	spin_unlock_irqrestore(&chan->lock, flags);
	164	}
	165	EXPORT_SYMBOL_GPL(pcc_mbox_free_channel);
	166
8b0f5788 PP	167	/*
	168	* PCC can be used with perf critical drivers such as CPPC
	169	* So it makes sense to locally cache the virtual address and
	170	* use it to read/write to PCC registers such as doorbell register
	171	*
	172	* The below read_register and write_registers are used to read and
	173	* write from perf critical registers such as PCC doorbell register
	174	*/
	175	static int read_register(void __iomem vaddr, u64 val, unsigned int bit_width)
	176	{
	177	int ret_val = 0;
	178
	179	switch (bit_width) {
	180	case 8:
	181	*val = readb(vaddr);
	182	break;
	183	case 16:
	184	*val = readw(vaddr);
	185	break;
	186	case 32:
	187	*val = readl(vaddr);
	188	break;
	189	case 64:
	190	*val = readq(vaddr);
	191	break;
	192	default:
	193	pr_debug("Error: Cannot read register of %u bit width",
	194	bit_width);
	195	ret_val = -EFAULT;
	196	break;
	197	}
	198	return ret_val;
	199	}
	200
	201	static int write_register(void __iomem *vaddr, u64 val, unsigned int bit_width)
	202	{
	203	int ret_val = 0;
	204
	205	switch (bit_width) {
	206	case 8:
	207	writeb(val, vaddr);
	208	break;
	209	case 16:
	210	writew(val, vaddr);
	211	break;
	212	case 32:
	213	writel(val, vaddr);
	214	break;
	215	case 64:
	216	writeq(val, vaddr);
	217	break;
	218	default:
	219	pr_debug("Error: Cannot write register of %u bit width",
	220	bit_width);
	221	ret_val = -EFAULT;
	222	break;
	223	}
	224	return ret_val;
	225	}
	226
86c22f8c	227	/**
33350e6b AC	228	* pcc_send_data - Called from Mailbox Controller code. Used
	229	* here only to ring the channel doorbell. The PCC client
	230	* specific read/write is done in the client driver in
	231	* order to maintain atomicity over PCC channel once
	232	* OS has control over it. See above for flow of operations.
86c22f8c	233	* @chan: Pointer to Mailbox channel over which to send data.
33350e6b AC	234	* @data: Client specific data written over channel. Used here
33350e6b AC	235	* only for debug after PCC transaction completes.
86c22f8c AC	236	*
	237	* Return: Err if something failed else 0 for success.
	238	*/
	239	static int pcc_send_data(struct mbox_chan chan, void data)
	240	{
	241	struct acpi_pcct_hw_reduced *pcct_ss = chan->con_priv;
8b0f5788	242	struct acpi_generic_address *doorbell;
86c22f8c AC	243	u64 doorbell_preserve;
	244	u64 doorbell_val;
	245	u64 doorbell_write;
8b0f5788 PP	246	u32 id = chan - pcc_mbox_channels;
	247	int ret = 0;
	248
	249	if (id >= pcc_mbox_ctrl.num_chans) {
	250	pr_debug("pcc_send_data: Invalid mbox_chan passed\n");
	251	return -ENOENT;
	252	}
86c22f8c	253
8b0f5788	254	doorbell = &pcct_ss->doorbell_register;
86c22f8c AC	255	doorbell_preserve = pcct_ss->preserve_mask;
	256	doorbell_write = pcct_ss->write_mask;
	257
33350e6b	258	/* Sync notification from OS to Platform. */
8b0f5788 PP	259	if (pcc_doorbell_vaddr[id]) {
	260	ret = read_register(pcc_doorbell_vaddr[id], &doorbell_val,
	261	doorbell->bit_width);
	262	if (ret)
	263	return ret;
	264	ret = write_register(pcc_doorbell_vaddr[id],
	265	(doorbell_val & doorbell_preserve) \| doorbell_write,
	266	doorbell->bit_width);
	267	} else {
	268	ret = acpi_read(&doorbell_val, doorbell);
	269	if (ret)
	270	return ret;
	271	ret = acpi_write((doorbell_val & doorbell_preserve) \| doorbell_write,
	272	doorbell);
	273	}
	274	return ret;
86c22f8c AC	275	}
86c22f8c AC	276
05ae7975	277	static const struct mbox_chan_ops pcc_chan_ops = {
86c22f8c	278	.send_data = pcc_send_data,
86c22f8c AC	279	};
	280
	281	/**
	282	* parse_pcc_subspace - Parse the PCC table and verify PCC subspace
	283	* entries. There should be one entry per PCC client.
	284	* @header: Pointer to the ACPI subtable header under the PCCT.
	285	* @end: End of subtable entry.
	286	*
	287	* Return: 0 for Success, else errno.
	288	*
	289	* This gets called for each entry in the PCC table.
	290	*/
	291	static int parse_pcc_subspace(struct acpi_subtable_header *header,
	292	const unsigned long end)
	293	{
	294	struct acpi_pcct_hw_reduced *pcct_ss;
	295
	296	if (pcc_mbox_ctrl.num_chans <= MAX_PCC_SUBSPACES) {
	297	pcct_ss = (struct acpi_pcct_hw_reduced *) header;
	298
	299	if (pcct_ss->header.type !=
	300	ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE) {
	301	pr_err("Incorrect PCC Subspace type detected\n");
	302	return -EINVAL;
	303	}
	304	}
	305
	306	return 0;
	307	}
	308
	309	/**
	310	* acpi_pcc_probe - Parse the ACPI tree for the PCCT.
	311	*
	312	* Return: 0 for Success, else errno.
	313	*/
	314	static int __init acpi_pcc_probe(void)
	315	{
	316	acpi_size pcct_tbl_header_size;
	317	struct acpi_table_header *pcct_tbl;
	318	struct acpi_subtable_header *pcct_entry;
	319	int count, i;
	320	acpi_status status = AE_OK;
	321
	322	/* Search for PCCT */
	323	status = acpi_get_table_with_size(ACPI_SIG_PCCT, 0,
	324	&pcct_tbl,
	325	&pcct_tbl_header_size);
	326
	327	if (ACPI_FAILURE(status) \|\| !pcct_tbl) {
	328	pr_warn("PCCT header not found.\n");
	329	return -ENODEV;
	330	}
	331
	332	count = acpi_table_parse_entries(ACPI_SIG_PCCT,
	333	sizeof(struct acpi_table_pcct),
	334	ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE,
	335	parse_pcc_subspace, MAX_PCC_SUBSPACES);
	336
	337	if (count <= 0) {
	338	pr_err("Error parsing PCC subspaces from PCCT\n");
	339	return -EINVAL;
	340	}
	341
	342	pcc_mbox_channels = kzalloc(sizeof(struct mbox_chan) *
343	count, GFP_KERNEL);
344
345	if (!pcc_mbox_channels) {
346	pr_err("Could not allocate space for PCC mbox channels\n");
347	return -ENOMEM;
348	}
349
8b0f5788 PP	350	pcc_doorbell_vaddr = kcalloc(count, sizeof(void *), GFP_KERNEL);
	351	if (!pcc_doorbell_vaddr) {
	352	kfree(pcc_mbox_channels);
	353	return -ENOMEM;
	354	}
	355
86c22f8c AC	356	/* Point to the first PCC subspace entry */
	357	pcct_entry = (struct acpi_subtable_header *) (
	358	(unsigned long) pcct_tbl + sizeof(struct acpi_table_pcct));
	359
	360	for (i = 0; i < count; i++) {
8b0f5788 PP	361	struct acpi_generic_address *db_reg;
8b0f5788 PP	362	struct acpi_pcct_hw_reduced *pcct_ss;
86c22f8c	363	pcc_mbox_channels[i].con_priv = pcct_entry;
8b0f5788 PP	364
	365	/* If doorbell is in system memory cache the virt address */
	366	pcct_ss = (struct acpi_pcct_hw_reduced *)pcct_entry;
	367	db_reg = &pcct_ss->doorbell_register;
	368	if (db_reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
	369	pcc_doorbell_vaddr[i] = acpi_os_ioremap(db_reg->address,
	370	db_reg->bit_width/8);
86c22f8c AC	371	pcct_entry = (struct acpi_subtable_header *)
	372	((unsigned long) pcct_entry + pcct_entry->length);
	373	}
	374
	375	pcc_mbox_ctrl.num_chans = count;
	376
	377	pr_info("Detected %d PCC Subspaces\n", pcc_mbox_ctrl.num_chans);
	378
	379	return 0;
	380	}
	381
	382	/**
	383	* pcc_mbox_probe - Called when we find a match for the
	384	* PCCT platform device. This is purely used to represent
	385	* the PCCT as a virtual device for registering with the
	386	* generic Mailbox framework.
	387	*
	388	* @pdev: Pointer to platform device returned when a match
	389	* is found.
	390	*
	391	* Return: 0 for Success, else errno.
	392	*/
	393	static int pcc_mbox_probe(struct platform_device *pdev)
	394	{
	395	int ret = 0;
	396
	397	pcc_mbox_ctrl.chans = pcc_mbox_channels;
	398	pcc_mbox_ctrl.ops = &pcc_chan_ops;
86c22f8c AC	399	pcc_mbox_ctrl.dev = &pdev->dev;
	400
	401	pr_info("Registering PCC driver as Mailbox controller\n");
	402	ret = mbox_controller_register(&pcc_mbox_ctrl);
	403
	404	if (ret) {
	405	pr_err("Err registering PCC as Mailbox controller: %d\n", ret);
	406	ret = -ENODEV;
	407	}
	408
	409	return ret;
	410	}
	411
	412	struct platform_driver pcc_mbox_driver = {
	413	.probe = pcc_mbox_probe,
	414	.driver = {
	415	.name = "PCCT",
	416	.owner = THIS_MODULE,
	417	},
	418	};
	419
	420	static int __init pcc_init(void)
	421	{
	422	int ret;
	423	struct platform_device *pcc_pdev;
	424
	425	if (acpi_disabled)
	426	return -ENODEV;
	427
	428	/* Check if PCC support is available. */
	429	ret = acpi_pcc_probe();
	430
	431	if (ret) {
efd756da	432	pr_debug("ACPI PCC probe failed.\n");
86c22f8c AC	433	return -ENODEV;
	434	}
	435
	436	pcc_pdev = platform_create_bundle(&pcc_mbox_driver,
	437	pcc_mbox_probe, NULL, 0, NULL, 0);
	438
356d5d28	439	if (IS_ERR(pcc_pdev)) {
efd756da	440	pr_debug("Err creating PCC platform bundle\n");
356d5d28	441	return PTR_ERR(pcc_pdev);
86c22f8c AC	442	}
	443
	444	return 0;
	445	}
d3c68f21 AC	446
	447	/*
	448	* Make PCC init postcore so that users of this mailbox
	449	* such as the ACPI Processor driver have it available
	450	* at their init.
	451	*/
	452	postcore_initcall(pcc_init);