453 строки
12 KiB
C
453 строки
12 KiB
C
/*
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* Copyright (C) 2014 Linaro Ltd.
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* Author: Ashwin Chaugule <ashwin.chaugule@linaro.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* PCC (Platform Communication Channel) is defined in the ACPI 5.0+
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* specification. It is a mailbox like mechanism to allow clients
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* such as CPPC (Collaborative Processor Performance Control), RAS
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* (Reliability, Availability and Serviceability) and MPST (Memory
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* Node Power State Table) to talk to the platform (e.g. BMC) through
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* shared memory regions as defined in the PCC table entries. The PCC
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* specification supports a Doorbell mechanism for the PCC clients
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* to notify the platform about new data. This Doorbell information
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* is also specified in each PCC table entry.
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*
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* Typical high level flow of operation is:
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*
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* PCC Reads:
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* * Client tries to acquire a channel lock.
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* * After it is acquired it writes READ cmd in communication region cmd
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* address.
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* * Client issues mbox_send_message() which rings the PCC doorbell
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* for its PCC channel.
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* * If command completes, then client has control over channel and
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* it can proceed with its reads.
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* * Client releases lock.
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*
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* PCC Writes:
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* * Client tries to acquire channel lock.
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* * Client writes to its communication region after it acquires a
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* channel lock.
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* * Client writes WRITE cmd in communication region cmd address.
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* * Client issues mbox_send_message() which rings the PCC doorbell
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* for its PCC channel.
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* * If command completes, then writes have succeded and it can release
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* the channel lock.
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*
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* There is a Nominal latency defined for each channel which indicates
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* how long to wait until a command completes. If command is not complete
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* the client needs to retry or assume failure.
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*
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* For more details about PCC, please see the ACPI specification from
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* http://www.uefi.org/ACPIv5.1 Section 14.
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*
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* This file implements PCC as a Mailbox controller and allows for PCC
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* clients to be implemented as its Mailbox Client Channels.
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*/
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#include <linux/acpi.h>
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#include <linux/delay.h>
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#include <linux/io.h>
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#include <linux/init.h>
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#include <linux/list.h>
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#include <linux/platform_device.h>
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#include <linux/mailbox_controller.h>
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#include <linux/mailbox_client.h>
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#include <linux/io-64-nonatomic-lo-hi.h>
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#include "mailbox.h"
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#define MAX_PCC_SUBSPACES 256
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static struct mbox_chan *pcc_mbox_channels;
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/* Array of cached virtual address for doorbell registers */
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static void __iomem **pcc_doorbell_vaddr;
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static struct mbox_controller pcc_mbox_ctrl = {};
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/**
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* get_pcc_channel - Given a PCC subspace idx, get
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* the respective mbox_channel.
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* @id: PCC subspace index.
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*
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* Return: ERR_PTR(errno) if error, else pointer
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* to mbox channel.
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*/
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static struct mbox_chan *get_pcc_channel(int id)
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{
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if (id < 0 || id > pcc_mbox_ctrl.num_chans)
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return ERR_PTR(-ENOENT);
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return &pcc_mbox_channels[id];
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}
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/**
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* pcc_mbox_request_channel - PCC clients call this function to
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* request a pointer to their PCC subspace, from which they
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* can get the details of communicating with the remote.
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* @cl: Pointer to Mailbox client, so we know where to bind the
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* Channel.
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* @subspace_id: The PCC Subspace index as parsed in the PCC client
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* ACPI package. This is used to lookup the array of PCC
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* subspaces as parsed by the PCC Mailbox controller.
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*
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* Return: Pointer to the Mailbox Channel if successful or
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* ERR_PTR.
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*/
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struct mbox_chan *pcc_mbox_request_channel(struct mbox_client *cl,
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int subspace_id)
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{
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struct device *dev = pcc_mbox_ctrl.dev;
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struct mbox_chan *chan;
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unsigned long flags;
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/*
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* Each PCC Subspace is a Mailbox Channel.
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* The PCC Clients get their PCC Subspace ID
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* from their own tables and pass it here.
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* This returns a pointer to the PCC subspace
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* for the Client to operate on.
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*/
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chan = get_pcc_channel(subspace_id);
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if (IS_ERR(chan) || chan->cl) {
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dev_err(dev, "Channel not found for idx: %d\n", subspace_id);
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return ERR_PTR(-EBUSY);
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}
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spin_lock_irqsave(&chan->lock, flags);
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chan->msg_free = 0;
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chan->msg_count = 0;
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chan->active_req = NULL;
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chan->cl = cl;
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init_completion(&chan->tx_complete);
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if (chan->txdone_method == TXDONE_BY_POLL && cl->knows_txdone)
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chan->txdone_method |= TXDONE_BY_ACK;
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spin_unlock_irqrestore(&chan->lock, flags);
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return chan;
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}
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EXPORT_SYMBOL_GPL(pcc_mbox_request_channel);
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/**
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* pcc_mbox_free_channel - Clients call this to free their Channel.
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*
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* @chan: Pointer to the mailbox channel as returned by
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* pcc_mbox_request_channel()
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*/
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void pcc_mbox_free_channel(struct mbox_chan *chan)
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{
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unsigned long flags;
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if (!chan || !chan->cl)
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return;
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spin_lock_irqsave(&chan->lock, flags);
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chan->cl = NULL;
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chan->active_req = NULL;
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if (chan->txdone_method == (TXDONE_BY_POLL | TXDONE_BY_ACK))
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chan->txdone_method = TXDONE_BY_POLL;
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spin_unlock_irqrestore(&chan->lock, flags);
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}
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EXPORT_SYMBOL_GPL(pcc_mbox_free_channel);
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/*
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* PCC can be used with perf critical drivers such as CPPC
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* So it makes sense to locally cache the virtual address and
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* use it to read/write to PCC registers such as doorbell register
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*
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* The below read_register and write_registers are used to read and
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* write from perf critical registers such as PCC doorbell register
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*/
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static int read_register(void __iomem *vaddr, u64 *val, unsigned int bit_width)
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{
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int ret_val = 0;
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switch (bit_width) {
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case 8:
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*val = readb(vaddr);
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break;
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case 16:
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*val = readw(vaddr);
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break;
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case 32:
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*val = readl(vaddr);
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break;
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case 64:
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*val = readq(vaddr);
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break;
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default:
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pr_debug("Error: Cannot read register of %u bit width",
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bit_width);
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ret_val = -EFAULT;
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break;
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}
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return ret_val;
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}
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static int write_register(void __iomem *vaddr, u64 val, unsigned int bit_width)
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{
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int ret_val = 0;
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switch (bit_width) {
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case 8:
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writeb(val, vaddr);
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break;
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case 16:
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writew(val, vaddr);
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break;
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case 32:
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writel(val, vaddr);
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break;
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case 64:
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writeq(val, vaddr);
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break;
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default:
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pr_debug("Error: Cannot write register of %u bit width",
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bit_width);
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ret_val = -EFAULT;
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break;
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}
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return ret_val;
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}
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/**
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* pcc_send_data - Called from Mailbox Controller code. Used
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* here only to ring the channel doorbell. The PCC client
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* specific read/write is done in the client driver in
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* order to maintain atomicity over PCC channel once
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* OS has control over it. See above for flow of operations.
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* @chan: Pointer to Mailbox channel over which to send data.
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* @data: Client specific data written over channel. Used here
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* only for debug after PCC transaction completes.
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*
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* Return: Err if something failed else 0 for success.
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*/
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static int pcc_send_data(struct mbox_chan *chan, void *data)
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{
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struct acpi_pcct_hw_reduced *pcct_ss = chan->con_priv;
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struct acpi_generic_address *doorbell;
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u64 doorbell_preserve;
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u64 doorbell_val;
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u64 doorbell_write;
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u32 id = chan - pcc_mbox_channels;
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int ret = 0;
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if (id >= pcc_mbox_ctrl.num_chans) {
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pr_debug("pcc_send_data: Invalid mbox_chan passed\n");
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return -ENOENT;
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}
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doorbell = &pcct_ss->doorbell_register;
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doorbell_preserve = pcct_ss->preserve_mask;
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doorbell_write = pcct_ss->write_mask;
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/* Sync notification from OS to Platform. */
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if (pcc_doorbell_vaddr[id]) {
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ret = read_register(pcc_doorbell_vaddr[id], &doorbell_val,
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doorbell->bit_width);
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if (ret)
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return ret;
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ret = write_register(pcc_doorbell_vaddr[id],
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(doorbell_val & doorbell_preserve) | doorbell_write,
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doorbell->bit_width);
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} else {
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ret = acpi_read(&doorbell_val, doorbell);
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if (ret)
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return ret;
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ret = acpi_write((doorbell_val & doorbell_preserve) | doorbell_write,
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doorbell);
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}
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return ret;
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}
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static const struct mbox_chan_ops pcc_chan_ops = {
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.send_data = pcc_send_data,
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};
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/**
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* parse_pcc_subspace - Parse the PCC table and verify PCC subspace
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* entries. There should be one entry per PCC client.
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* @header: Pointer to the ACPI subtable header under the PCCT.
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* @end: End of subtable entry.
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*
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* Return: 0 for Success, else errno.
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*
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* This gets called for each entry in the PCC table.
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*/
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static int parse_pcc_subspace(struct acpi_subtable_header *header,
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const unsigned long end)
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{
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struct acpi_pcct_hw_reduced *pcct_ss;
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if (pcc_mbox_ctrl.num_chans <= MAX_PCC_SUBSPACES) {
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pcct_ss = (struct acpi_pcct_hw_reduced *) header;
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if (pcct_ss->header.type !=
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ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE) {
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pr_err("Incorrect PCC Subspace type detected\n");
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return -EINVAL;
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}
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}
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return 0;
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}
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/**
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* acpi_pcc_probe - Parse the ACPI tree for the PCCT.
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*
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* Return: 0 for Success, else errno.
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*/
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static int __init acpi_pcc_probe(void)
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{
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acpi_size pcct_tbl_header_size;
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struct acpi_table_header *pcct_tbl;
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struct acpi_subtable_header *pcct_entry;
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int count, i;
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acpi_status status = AE_OK;
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/* Search for PCCT */
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status = acpi_get_table_with_size(ACPI_SIG_PCCT, 0,
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&pcct_tbl,
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&pcct_tbl_header_size);
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if (ACPI_FAILURE(status) || !pcct_tbl) {
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pr_warn("PCCT header not found.\n");
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return -ENODEV;
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}
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count = acpi_table_parse_entries(ACPI_SIG_PCCT,
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sizeof(struct acpi_table_pcct),
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ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE,
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parse_pcc_subspace, MAX_PCC_SUBSPACES);
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if (count <= 0) {
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pr_err("Error parsing PCC subspaces from PCCT\n");
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return -EINVAL;
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}
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pcc_mbox_channels = kzalloc(sizeof(struct mbox_chan) *
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count, GFP_KERNEL);
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if (!pcc_mbox_channels) {
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pr_err("Could not allocate space for PCC mbox channels\n");
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return -ENOMEM;
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}
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pcc_doorbell_vaddr = kcalloc(count, sizeof(void *), GFP_KERNEL);
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if (!pcc_doorbell_vaddr) {
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kfree(pcc_mbox_channels);
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return -ENOMEM;
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}
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/* Point to the first PCC subspace entry */
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pcct_entry = (struct acpi_subtable_header *) (
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(unsigned long) pcct_tbl + sizeof(struct acpi_table_pcct));
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for (i = 0; i < count; i++) {
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struct acpi_generic_address *db_reg;
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struct acpi_pcct_hw_reduced *pcct_ss;
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pcc_mbox_channels[i].con_priv = pcct_entry;
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/* If doorbell is in system memory cache the virt address */
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pcct_ss = (struct acpi_pcct_hw_reduced *)pcct_entry;
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db_reg = &pcct_ss->doorbell_register;
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if (db_reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
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pcc_doorbell_vaddr[i] = acpi_os_ioremap(db_reg->address,
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db_reg->bit_width/8);
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pcct_entry = (struct acpi_subtable_header *)
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((unsigned long) pcct_entry + pcct_entry->length);
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}
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pcc_mbox_ctrl.num_chans = count;
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pr_info("Detected %d PCC Subspaces\n", pcc_mbox_ctrl.num_chans);
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return 0;
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}
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/**
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* pcc_mbox_probe - Called when we find a match for the
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* PCCT platform device. This is purely used to represent
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* the PCCT as a virtual device for registering with the
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* generic Mailbox framework.
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*
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* @pdev: Pointer to platform device returned when a match
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* is found.
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*
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* Return: 0 for Success, else errno.
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*/
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static int pcc_mbox_probe(struct platform_device *pdev)
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{
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int ret = 0;
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pcc_mbox_ctrl.chans = pcc_mbox_channels;
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pcc_mbox_ctrl.ops = &pcc_chan_ops;
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pcc_mbox_ctrl.dev = &pdev->dev;
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pr_info("Registering PCC driver as Mailbox controller\n");
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ret = mbox_controller_register(&pcc_mbox_ctrl);
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if (ret) {
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pr_err("Err registering PCC as Mailbox controller: %d\n", ret);
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ret = -ENODEV;
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}
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return ret;
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}
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struct platform_driver pcc_mbox_driver = {
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.probe = pcc_mbox_probe,
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.driver = {
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.name = "PCCT",
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.owner = THIS_MODULE,
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},
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};
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static int __init pcc_init(void)
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{
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int ret;
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struct platform_device *pcc_pdev;
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if (acpi_disabled)
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return -ENODEV;
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/* Check if PCC support is available. */
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ret = acpi_pcc_probe();
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if (ret) {
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pr_debug("ACPI PCC probe failed.\n");
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return -ENODEV;
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}
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pcc_pdev = platform_create_bundle(&pcc_mbox_driver,
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pcc_mbox_probe, NULL, 0, NULL, 0);
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if (IS_ERR(pcc_pdev)) {
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pr_debug("Err creating PCC platform bundle\n");
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return PTR_ERR(pcc_pdev);
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}
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return 0;
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}
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/*
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* Make PCC init postcore so that users of this mailbox
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* such as the ACPI Processor driver have it available
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* at their init.
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*/
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postcore_initcall(pcc_init);
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