X-Git-Url: https://gerrit.opnfv.org/gerrit/gitweb?a=blobdiff_plain;f=kernel%2Fdrivers%2Fmailbox%2Fpcc.c;fp=kernel%2Fdrivers%2Fmailbox%2Fpcc.c;h=7e91d68a3ac3d02b2622315b2745f605c5961300;hb=9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00;hp=0000000000000000000000000000000000000000;hpb=98260f3884f4a202f9ca5eabed40b1354c489b29;p=kvmfornfv.git diff --git a/kernel/drivers/mailbox/pcc.c b/kernel/drivers/mailbox/pcc.c new file mode 100644 index 000000000..7e91d68a3 --- /dev/null +++ b/kernel/drivers/mailbox/pcc.c @@ -0,0 +1,355 @@ +/* + * Copyright (C) 2014 Linaro Ltd. + * Author: Ashwin Chaugule + * + * 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 +#include +#include +#include +#include +#include +#include +#include + +#include "mailbox.h" + +#define MAX_PCC_SUBSPACES 256 + +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; +} + +/** + * 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, "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_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; + + doorbell = pcct_ss->doorbell_register; + doorbell_preserve = pcct_ss->preserve_mask; + doorbell_write = pcct_ss->write_mask; + + /* Sync notification from OS 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, +}; + +/** + * 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.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; +} +device_initcall(pcc_init);