| // SPDX-License-Identifier: GPL-2.0-or-later |
| /* |
| * Copyright (C) 2014 Linaro Ltd. |
| * Author: Ashwin Chaugule <ashwin.chaugule@linaro.org> |
| * |
| * 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/interrupt.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 <acpi/pcc.h> |
| |
| #include "mailbox.h" |
| |
| #define MBOX_IRQ_NAME "pcc-mbox" |
| |
| static struct mbox_chan *pcc_mbox_channels; |
| |
| /* Array of cached virtual address for doorbell registers */ |
| static void __iomem **pcc_doorbell_vaddr; |
| /* Array of cached virtual address for doorbell ack registers */ |
| static void __iomem **pcc_doorbell_ack_vaddr; |
| /* Array of doorbell interrupts */ |
| static int *pcc_doorbell_irq; |
| |
| 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 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_map_interrupt - Map a PCC subspace GSI to a linux IRQ number |
| * @interrupt: GSI number. |
| * @flags: interrupt flags |
| * |
| * Returns: a valid linux IRQ number on success |
| * 0 or -EINVAL on failure |
| */ |
| static int pcc_map_interrupt(u32 interrupt, u32 flags) |
| { |
| int trigger, polarity; |
| |
| if (!interrupt) |
| return 0; |
| |
| trigger = (flags & ACPI_PCCT_INTERRUPT_MODE) ? ACPI_EDGE_SENSITIVE |
| : ACPI_LEVEL_SENSITIVE; |
| |
| polarity = (flags & ACPI_PCCT_INTERRUPT_POLARITY) ? ACPI_ACTIVE_LOW |
| : ACPI_ACTIVE_HIGH; |
| |
| return acpi_register_gsi(NULL, interrupt, trigger, polarity); |
| } |
| |
| /** |
| * pcc_mbox_irq - PCC mailbox interrupt handler |
| */ |
| static irqreturn_t pcc_mbox_irq(int irq, void *p) |
| { |
| struct acpi_generic_address *doorbell_ack; |
| struct acpi_pcct_hw_reduced *pcct_ss; |
| struct mbox_chan *chan = p; |
| u64 doorbell_ack_preserve; |
| u64 doorbell_ack_write; |
| u64 doorbell_ack_val; |
| int ret; |
| |
| pcct_ss = chan->con_priv; |
| |
| mbox_chan_received_data(chan, NULL); |
| |
| if (pcct_ss->header.type == ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) { |
| struct acpi_pcct_hw_reduced_type2 *pcct2_ss = chan->con_priv; |
| u32 id = chan - pcc_mbox_channels; |
| |
| doorbell_ack = &pcct2_ss->platform_ack_register; |
| doorbell_ack_preserve = pcct2_ss->ack_preserve_mask; |
| doorbell_ack_write = pcct2_ss->ack_write_mask; |
| |
| ret = read_register(pcc_doorbell_ack_vaddr[id], |
| &doorbell_ack_val, |
| doorbell_ack->bit_width); |
| if (ret) |
| return IRQ_NONE; |
| |
| ret = write_register(pcc_doorbell_ack_vaddr[id], |
| (doorbell_ack_val & doorbell_ack_preserve) |
| | doorbell_ack_write, |
| doorbell_ack->bit_width); |
| if (ret) |
| return IRQ_NONE; |
| } |
| |
| return IRQ_HANDLED; |
| } |
| |
| /** |
| * 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); |
| |
| if (pcc_doorbell_irq[subspace_id] > 0) { |
| int rc; |
| |
| rc = devm_request_irq(dev, pcc_doorbell_irq[subspace_id], |
| pcc_mbox_irq, 0, MBOX_IRQ_NAME, chan); |
| if (unlikely(rc)) { |
| dev_err(dev, "failed to register PCC interrupt %d\n", |
| pcc_doorbell_irq[subspace_id]); |
| pcc_mbox_free_channel(chan); |
| chan = ERR_PTR(rc); |
| } |
| } |
| |
| 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) |
| { |
| u32 id = chan - pcc_mbox_channels; |
| unsigned long flags; |
| |
| if (!chan || !chan->cl) |
| return; |
| |
| if (id >= pcc_mbox_ctrl.num_chans) { |
| pr_debug("pcc_mbox_free_channel: Invalid mbox_chan passed\n"); |
| return; |
| } |
| |
| if (pcc_doorbell_irq[id] > 0) |
| devm_free_irq(chan->mbox->dev, pcc_doorbell_irq[id], chan); |
| |
| spin_lock_irqsave(&chan->lock, flags); |
| chan->cl = NULL; |
| chan->active_req = NULL; |
| if (chan->txdone_method == 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; |
| 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_subspaces -- Count PCC subspaces defined |
| * @header: Pointer to the ACPI subtable header under the PCCT. |
| * @end: End of subtable entry. |
| * |
| * Return: If we find a PCC subspace entry of a valid type, return 0. |
| * Otherwise, return -EINVAL. |
| * |
| * This gets called for each entry in the PCC table. |
| */ |
| static int parse_pcc_subspace(union acpi_subtable_headers *header, |
| const unsigned long end) |
| { |
| struct acpi_pcct_subspace *ss = (struct acpi_pcct_subspace *) header; |
| |
| if (ss->header.type < ACPI_PCCT_TYPE_RESERVED) |
| return 0; |
| |
| return -EINVAL; |
| } |
| |
| /** |
| * pcc_parse_subspace_irq - Parse the PCC IRQ and PCC ACK register |
| * There should be one entry per PCC client. |
| * @id: PCC subspace index. |
| * @pcct_ss: Pointer to the ACPI subtable header under the PCCT. |
| * |
| * Return: 0 for Success, else errno. |
| * |
| * This gets called for each entry in the PCC table. |
| */ |
| static int pcc_parse_subspace_irq(int id, |
| struct acpi_pcct_hw_reduced *pcct_ss) |
| { |
| pcc_doorbell_irq[id] = pcc_map_interrupt(pcct_ss->platform_interrupt, |
| (u32)pcct_ss->flags); |
| if (pcc_doorbell_irq[id] <= 0) { |
| pr_err("PCC GSI %d not registered\n", |
| pcct_ss->platform_interrupt); |
| return -EINVAL; |
| } |
| |
| if (pcct_ss->header.type |
| == ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) { |
| struct acpi_pcct_hw_reduced_type2 *pcct2_ss = (void *)pcct_ss; |
| |
| pcc_doorbell_ack_vaddr[id] = acpi_os_ioremap( |
| pcct2_ss->platform_ack_register.address, |
| pcct2_ss->platform_ack_register.bit_width / 8); |
| if (!pcc_doorbell_ack_vaddr[id]) { |
| pr_err("Failed to ioremap PCC ACK register\n"); |
| return -ENOMEM; |
| } |
| } |
| |
| 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) |
| { |
| struct acpi_table_header *pcct_tbl; |
| struct acpi_subtable_header *pcct_entry; |
| struct acpi_table_pcct *acpi_pcct_tbl; |
| struct acpi_subtable_proc proc[ACPI_PCCT_TYPE_RESERVED]; |
| int count, i, rc; |
| acpi_status status = AE_OK; |
| |
| /* Search for PCCT */ |
| status = acpi_get_table(ACPI_SIG_PCCT, 0, &pcct_tbl); |
| |
| if (ACPI_FAILURE(status) || !pcct_tbl) |
| return -ENODEV; |
| |
| /* Set up the subtable handlers */ |
| for (i = ACPI_PCCT_TYPE_GENERIC_SUBSPACE; |
| i < ACPI_PCCT_TYPE_RESERVED; i++) { |
| proc[i].id = i; |
| proc[i].count = 0; |
| proc[i].handler = parse_pcc_subspace; |
| } |
| |
| count = acpi_table_parse_entries_array(ACPI_SIG_PCCT, |
| sizeof(struct acpi_table_pcct), proc, |
| ACPI_PCCT_TYPE_RESERVED, MAX_PCC_SUBSPACES); |
| if (count <= 0 || count > MAX_PCC_SUBSPACES) { |
| if (count < 0) |
| pr_warn("Error parsing PCC subspaces from PCCT\n"); |
| else |
| pr_warn("Invalid PCCT: %d PCC subspaces\n", count); |
| return -EINVAL; |
| } |
| |
| pcc_mbox_channels = kcalloc(count, sizeof(struct mbox_chan), |
| 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) { |
| rc = -ENOMEM; |
| goto err_free_mbox; |
| } |
| |
| pcc_doorbell_ack_vaddr = kcalloc(count, sizeof(void *), GFP_KERNEL); |
| if (!pcc_doorbell_ack_vaddr) { |
| rc = -ENOMEM; |
| goto err_free_db_vaddr; |
| } |
| |
| pcc_doorbell_irq = kcalloc(count, sizeof(int), GFP_KERNEL); |
| if (!pcc_doorbell_irq) { |
| rc = -ENOMEM; |
| goto err_free_db_ack_vaddr; |
| } |
| |
| /* Point to the first PCC subspace entry */ |
| pcct_entry = (struct acpi_subtable_header *) ( |
| (unsigned long) pcct_tbl + sizeof(struct acpi_table_pcct)); |
| |
| acpi_pcct_tbl = (struct acpi_table_pcct *) pcct_tbl; |
| if (acpi_pcct_tbl->flags & ACPI_PCCT_DOORBELL) |
| pcc_mbox_ctrl.txdone_irq = true; |
| |
| for (i = 0; i < count; i++) { |
| struct acpi_generic_address *db_reg; |
| struct acpi_pcct_subspace *pcct_ss; |
| pcc_mbox_channels[i].con_priv = pcct_entry; |
| |
| if (pcct_entry->type == ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE || |
| pcct_entry->type == ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) { |
| struct acpi_pcct_hw_reduced *pcct_hrss; |
| |
| pcct_hrss = (struct acpi_pcct_hw_reduced *) pcct_entry; |
| |
| if (pcc_mbox_ctrl.txdone_irq) { |
| rc = pcc_parse_subspace_irq(i, pcct_hrss); |
| if (rc < 0) |
| goto err; |
| } |
| } |
| pcct_ss = (struct acpi_pcct_subspace *) pcct_entry; |
| |
| /* If doorbell is in system memory cache the virt address */ |
| 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; |
| |
| err: |
| kfree(pcc_doorbell_irq); |
| err_free_db_ack_vaddr: |
| kfree(pcc_doorbell_ack_vaddr); |
| err_free_db_vaddr: |
| kfree(pcc_doorbell_vaddr); |
| err_free_mbox: |
| kfree(pcc_mbox_channels); |
| return rc; |
| } |
| |
| /** |
| * 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; |
| } |
| |
| static 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); |