// SPDX-License-Identifier: GPL-2.0-or-later /* * Copyright (C) 2014 Linaro Ltd. * Author: Ashwin Chaugule * * 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 succeeded 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 #include #include #include #include "mailbox.h" #define MBOX_IRQ_NAME "pcc-mbox" /** * struct pcc_chan_reg - PCC register bundle * * @vaddr: cached virtual address for this register * @gas: pointer to the generic address structure for this register * @preserve_mask: bitmask to preserve when writing to this register * @set_mask: bitmask to set when writing to this register * @status_mask: bitmask to determine and/or update the status for this register */ struct pcc_chan_reg { void __iomem *vaddr; struct acpi_generic_address *gas; u64 preserve_mask; u64 set_mask; u64 status_mask; }; /** * struct pcc_chan_info - PCC channel specific information * * @chan: PCC channel information with Shared Memory Region info * @db: PCC register bundle for the doorbell register * @plat_irq_ack: PCC register bundle for the platform interrupt acknowledge * register * @cmd_complete: PCC register bundle for the command complete check register * @cmd_update: PCC register bundle for the command complete update register * @error: PCC register bundle for the error status register * @plat_irq: platform interrupt * @type: PCC subspace type * @plat_irq_flags: platform interrupt flags * @chan_in_use: this flag is used just to check if the interrupt needs * handling when it is shared. Since only one transfer can occur * at a time and mailbox takes care of locking, this flag can be * accessed without a lock. Note: the type only support the * communication from OSPM to Platform, like type3, use it, and * other types completely ignore it. */ struct pcc_chan_info { struct pcc_mbox_chan chan; struct pcc_chan_reg db; struct pcc_chan_reg plat_irq_ack; struct pcc_chan_reg cmd_complete; struct pcc_chan_reg cmd_update; struct pcc_chan_reg error; int plat_irq; u8 type; unsigned int plat_irq_flags; bool chan_in_use; }; #define to_pcc_chan_info(c) container_of(c, struct pcc_chan_info, chan) static struct pcc_chan_info *chan_info; static int pcc_chan_count; static int pcc_send_data(struct mbox_chan *chan, void *data); /* * 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 void read_register(void __iomem *vaddr, u64 *val, unsigned int bit_width) { 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; } } static void write_register(void __iomem *vaddr, u64 val, unsigned int bit_width) { 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; } } static int pcc_chan_reg_read(struct pcc_chan_reg *reg, u64 *val) { int ret = 0; if (!reg->gas) { *val = 0; return 0; } if (reg->vaddr) read_register(reg->vaddr, val, reg->gas->bit_width); else ret = acpi_read(val, reg->gas); return ret; } static int pcc_chan_reg_write(struct pcc_chan_reg *reg, u64 val) { int ret = 0; if (!reg->gas) return 0; if (reg->vaddr) write_register(reg->vaddr, val, reg->gas->bit_width); else ret = acpi_write(val, reg->gas); return ret; } static int pcc_chan_reg_read_modify_write(struct pcc_chan_reg *reg) { int ret = 0; u64 val; ret = pcc_chan_reg_read(reg, &val); if (ret) return ret; val &= reg->preserve_mask; val |= reg->set_mask; return pcc_chan_reg_write(reg, 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); } static bool pcc_chan_plat_irq_can_be_shared(struct pcc_chan_info *pchan) { return (pchan->plat_irq_flags & ACPI_PCCT_INTERRUPT_MODE) == ACPI_LEVEL_SENSITIVE; } static bool pcc_mbox_cmd_complete_check(struct pcc_chan_info *pchan) { u64 val; int ret; ret = pcc_chan_reg_read(&pchan->cmd_complete, &val); if (ret) return false; if (!pchan->cmd_complete.gas) return true; /* * Judge if the channel respond the interrupt based on the value of * command complete. */ val &= pchan->cmd_complete.status_mask; /* * If this is PCC slave subspace channel, and the command complete * bit 0 indicates that Platform is sending a notification and OSPM * needs to respond this interrupt to process this command. */ if (pchan->type == ACPI_PCCT_TYPE_EXT_PCC_SLAVE_SUBSPACE) return !val; return !!val; } /** * pcc_mbox_irq - PCC mailbox interrupt handler * @irq: interrupt number * @p: data/cookie passed from the caller to identify the channel * * Returns: IRQ_HANDLED if interrupt is handled or IRQ_NONE if not */ static irqreturn_t pcc_mbox_irq(int irq, void *p) { struct pcc_chan_info *pchan; struct mbox_chan *chan = p; u64 val; int ret; pchan = chan->con_priv; if (pchan->type == ACPI_PCCT_TYPE_EXT_PCC_MASTER_SUBSPACE && !pchan->chan_in_use) return IRQ_NONE; if (!pcc_mbox_cmd_complete_check(pchan)) return IRQ_NONE; ret = pcc_chan_reg_read(&pchan->error, &val); if (ret) return IRQ_NONE; val &= pchan->error.status_mask; if (val) { val &= ~pchan->error.status_mask; pcc_chan_reg_write(&pchan->error, val); return IRQ_NONE; } if (pcc_chan_reg_read_modify_write(&pchan->plat_irq_ack)) return IRQ_NONE; mbox_chan_received_data(chan, NULL); /* * The PCC slave subspace channel needs to set the command complete bit * and ring doorbell after processing message. * * The PCC master subspace channel clears chan_in_use to free channel. */ if (pchan->type == ACPI_PCCT_TYPE_EXT_PCC_SLAVE_SUBSPACE) pcc_send_data(chan, NULL); pchan->chan_in_use = false; 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 PCC Mailbox Channel if successful or ERR_PTR. */ struct pcc_mbox_chan * pcc_mbox_request_channel(struct mbox_client *cl, int subspace_id) { struct pcc_chan_info *pchan; struct mbox_chan *chan; int rc; if (subspace_id < 0 || subspace_id >= pcc_chan_count) return ERR_PTR(-ENOENT); pchan = chan_info + subspace_id; chan = pchan->chan.mchan; if (IS_ERR(chan) || chan->cl) { pr_err("Channel not found for idx: %d\n", subspace_id); return ERR_PTR(-EBUSY); } rc = mbox_bind_client(chan, cl); if (rc) return ERR_PTR(rc); return &pchan->chan; } EXPORT_SYMBOL_GPL(pcc_mbox_request_channel); /** * pcc_mbox_free_channel - Clients call this to free their Channel. * * @pchan: Pointer to the PCC mailbox channel as returned by * pcc_mbox_request_channel() */ void pcc_mbox_free_channel(struct pcc_mbox_chan *pchan) { struct mbox_chan *chan = pchan->mchan; if (!chan || !chan->cl) return; mbox_free_channel(chan); } 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) { int ret; struct pcc_chan_info *pchan = chan->con_priv; ret = pcc_chan_reg_read_modify_write(&pchan->cmd_update); if (ret) return ret; ret = pcc_chan_reg_read_modify_write(&pchan->db); if (!ret && pchan->plat_irq > 0) pchan->chan_in_use = true; return ret; } /** * pcc_startup - Called from Mailbox Controller code. Used here * to request the interrupt. * @chan: Pointer to Mailbox channel to startup. * * Return: Err if something failed else 0 for success. */ static int pcc_startup(struct mbox_chan *chan) { struct pcc_chan_info *pchan = chan->con_priv; unsigned long irqflags; int rc; if (pchan->plat_irq > 0) { irqflags = pcc_chan_plat_irq_can_be_shared(pchan) ? IRQF_SHARED | IRQF_ONESHOT : 0; rc = devm_request_irq(chan->mbox->dev, pchan->plat_irq, pcc_mbox_irq, irqflags, MBOX_IRQ_NAME, chan); if (unlikely(rc)) { dev_err(chan->mbox->dev, "failed to register PCC interrupt %d\n", pchan->plat_irq); return rc; } } return 0; } /** * pcc_shutdown - Called from Mailbox Controller code. Used here * to free the interrupt. * @chan: Pointer to Mailbox channel to shutdown. */ static void pcc_shutdown(struct mbox_chan *chan) { struct pcc_chan_info *pchan = chan->con_priv; if (pchan->plat_irq > 0) devm_free_irq(chan->mbox->dev, pchan->plat_irq, chan); } static const struct mbox_chan_ops pcc_chan_ops = { .send_data = pcc_send_data, .startup = pcc_startup, .shutdown = pcc_shutdown, }; /** * parse_pcc_subspace - 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; } static int pcc_chan_reg_init(struct pcc_chan_reg *reg, struct acpi_generic_address *gas, u64 preserve_mask, u64 set_mask, u64 status_mask, char *name) { if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) { if (!(gas->bit_width >= 8 && gas->bit_width <= 64 && is_power_of_2(gas->bit_width))) { pr_err("Error: Cannot access register of %u bit width", gas->bit_width); return -EFAULT; } reg->vaddr = acpi_os_ioremap(gas->address, gas->bit_width / 8); if (!reg->vaddr) { pr_err("Failed to ioremap PCC %s register\n", name); return -ENOMEM; } } reg->gas = gas; reg->preserve_mask = preserve_mask; reg->set_mask = set_mask; reg->status_mask = status_mask; return 0; } /** * pcc_parse_subspace_irq - Parse the PCC IRQ and PCC ACK register * * @pchan: Pointer to the PCC channel info structure. * @pcct_entry: Pointer to the ACPI subtable header. * * Return: 0 for Success, else errno. * * There should be one entry per PCC channel. This gets called for each * entry in the PCC table. This uses PCCY Type1 structure for all applicable * types(Type 1-4) to fetch irq */ static int pcc_parse_subspace_irq(struct pcc_chan_info *pchan, struct acpi_subtable_header *pcct_entry) { int ret = 0; struct acpi_pcct_hw_reduced *pcct_ss; if (pcct_entry->type < ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE || pcct_entry->type > ACPI_PCCT_TYPE_EXT_PCC_SLAVE_SUBSPACE) return 0; pcct_ss = (struct acpi_pcct_hw_reduced *)pcct_entry; pchan->plat_irq = pcc_map_interrupt(pcct_ss->platform_interrupt, (u32)pcct_ss->flags); if (pchan->plat_irq <= 0) { pr_err("PCC GSI %d not registered\n", pcct_ss->platform_interrupt); return -EINVAL; } pchan->plat_irq_flags = pcct_ss->flags; if (pcct_ss->header.type == ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) { struct acpi_pcct_hw_reduced_type2 *pcct2_ss = (void *)pcct_ss; ret = pcc_chan_reg_init(&pchan->plat_irq_ack, &pcct2_ss->platform_ack_register, pcct2_ss->ack_preserve_mask, pcct2_ss->ack_write_mask, 0, "PLAT IRQ ACK"); } else if (pcct_ss->header.type == ACPI_PCCT_TYPE_EXT_PCC_MASTER_SUBSPACE || pcct_ss->header.type == ACPI_PCCT_TYPE_EXT_PCC_SLAVE_SUBSPACE) { struct acpi_pcct_ext_pcc_master *pcct_ext = (void *)pcct_ss; ret = pcc_chan_reg_init(&pchan->plat_irq_ack, &pcct_ext->platform_ack_register, pcct_ext->ack_preserve_mask, pcct_ext->ack_set_mask, 0, "PLAT IRQ ACK"); } if (pcc_chan_plat_irq_can_be_shared(pchan) && !pchan->plat_irq_ack.gas) { pr_err("PCC subspace has level IRQ with no ACK register\n"); return -EINVAL; } return ret; } /** * pcc_parse_subspace_db_reg - Parse the PCC doorbell register * * @pchan: Pointer to the PCC channel info structure. * @pcct_entry: Pointer to the ACPI subtable header. * * Return: 0 for Success, else errno. */ static int pcc_parse_subspace_db_reg(struct pcc_chan_info *pchan, struct acpi_subtable_header *pcct_entry) { int ret = 0; if (pcct_entry->type <= ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) { struct acpi_pcct_subspace *pcct_ss; pcct_ss = (struct acpi_pcct_subspace *)pcct_entry; ret = pcc_chan_reg_init(&pchan->db, &pcct_ss->doorbell_register, pcct_ss->preserve_mask, pcct_ss->write_mask, 0, "Doorbell"); } else { struct acpi_pcct_ext_pcc_master *pcct_ext; pcct_ext = (struct acpi_pcct_ext_pcc_master *)pcct_entry; ret = pcc_chan_reg_init(&pchan->db, &pcct_ext->doorbell_register, pcct_ext->preserve_mask, pcct_ext->write_mask, 0, "Doorbell"); if (ret) return ret; ret = pcc_chan_reg_init(&pchan->cmd_complete, &pcct_ext->cmd_complete_register, 0, 0, pcct_ext->cmd_complete_mask, "Command Complete Check"); if (ret) return ret; ret = pcc_chan_reg_init(&pchan->cmd_update, &pcct_ext->cmd_update_register, pcct_ext->cmd_update_preserve_mask, pcct_ext->cmd_update_set_mask, 0, "Command Complete Update"); if (ret) return ret; ret = pcc_chan_reg_init(&pchan->error, &pcct_ext->error_status_register, 0, 0, pcct_ext->error_status_mask, "Error Status"); } return ret; } /** * pcc_parse_subspace_shmem - Parse the PCC Shared Memory Region information * * @pchan: Pointer to the PCC channel info structure. * @pcct_entry: Pointer to the ACPI subtable header. * */ static void pcc_parse_subspace_shmem(struct pcc_chan_info *pchan, struct acpi_subtable_header *pcct_entry) { if (pcct_entry->type <= ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) { struct acpi_pcct_subspace *pcct_ss = (struct acpi_pcct_subspace *)pcct_entry; pchan->chan.shmem_base_addr = pcct_ss->base_address; pchan->chan.shmem_size = pcct_ss->length; pchan->chan.latency = pcct_ss->latency; pchan->chan.max_access_rate = pcct_ss->max_access_rate; pchan->chan.min_turnaround_time = pcct_ss->min_turnaround_time; } else { struct acpi_pcct_ext_pcc_master *pcct_ext = (struct acpi_pcct_ext_pcc_master *)pcct_entry; pchan->chan.shmem_base_addr = pcct_ext->base_address; pchan->chan.shmem_size = pcct_ext->length; pchan->chan.latency = pcct_ext->latency; pchan->chan.max_access_rate = pcct_ext->max_access_rate; pchan->chan.min_turnaround_time = pcct_ext->min_turnaround_time; } } /** * acpi_pcc_probe - Parse the ACPI tree for the PCCT. * * Return: 0 for Success, else errno. */ static int __init acpi_pcc_probe(void) { int count, i, rc = 0; acpi_status status; struct acpi_table_header *pcct_tbl; struct acpi_subtable_proc proc[ACPI_PCCT_TYPE_RESERVED]; 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); rc = -EINVAL; } else { pcc_chan_count = count; } acpi_put_table(pcct_tbl); 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) { struct device *dev = &pdev->dev; struct mbox_controller *pcc_mbox_ctrl; struct mbox_chan *pcc_mbox_channels; struct acpi_table_header *pcct_tbl; struct acpi_subtable_header *pcct_entry; struct acpi_table_pcct *acpi_pcct_tbl; acpi_status status = AE_OK; int i, rc, count = pcc_chan_count; /* Search for PCCT */ status = acpi_get_table(ACPI_SIG_PCCT, 0, &pcct_tbl); if (ACPI_FAILURE(status) || !pcct_tbl) return -ENODEV; pcc_mbox_channels = devm_kcalloc(dev, count, sizeof(*pcc_mbox_channels), GFP_KERNEL); if (!pcc_mbox_channels) { rc = -ENOMEM; goto err; } chan_info = devm_kcalloc(dev, count, sizeof(*chan_info), GFP_KERNEL); if (!chan_info) { rc = -ENOMEM; goto err; } pcc_mbox_ctrl = devm_kzalloc(dev, sizeof(*pcc_mbox_ctrl), GFP_KERNEL); if (!pcc_mbox_ctrl) { rc = -ENOMEM; goto err; } /* 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 pcc_chan_info *pchan = chan_info + i; pcc_mbox_channels[i].con_priv = pchan; pchan->chan.mchan = &pcc_mbox_channels[i]; if (pcct_entry->type == ACPI_PCCT_TYPE_EXT_PCC_SLAVE_SUBSPACE && !pcc_mbox_ctrl->txdone_irq) { pr_err("Platform Interrupt flag must be set to 1"); rc = -EINVAL; goto err; } if (pcc_mbox_ctrl->txdone_irq) { rc = pcc_parse_subspace_irq(pchan, pcct_entry); if (rc < 0) goto err; } rc = pcc_parse_subspace_db_reg(pchan, pcct_entry); if (rc < 0) goto err; pcc_parse_subspace_shmem(pchan, pcct_entry); pchan->type = pcct_entry->type; 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); pcc_mbox_ctrl->chans = pcc_mbox_channels; pcc_mbox_ctrl->ops = &pcc_chan_ops; pcc_mbox_ctrl->dev = dev; pr_info("Registering PCC driver as Mailbox controller\n"); rc = mbox_controller_register(pcc_mbox_ctrl); if (rc) pr_err("Err registering PCC as Mailbox controller: %d\n", rc); else return 0; err: acpi_put_table(pcct_tbl); return rc; } static struct platform_driver pcc_mbox_driver = { .probe = pcc_mbox_probe, .driver = { .name = "PCCT", }, }; 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"); pcc_chan_count = 0; 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);