diff options
Diffstat (limited to '')
| -rw-r--r-- | drivers/mailbox/pcc.c | 616 |
1 files changed, 616 insertions, 0 deletions
diff --git a/drivers/mailbox/pcc.c b/drivers/mailbox/pcc.c new file mode 100644 index 000000000..ef9ecd1f5 --- /dev/null +++ b/drivers/mailbox/pcc.c @@ -0,0 +1,616 @@ +// 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); + + rc = -EINVAL; + goto err_put_pcct; + } + + 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"); + rc = -ENOMEM; + goto err_put_pcct; + } + + 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); +err_put_pcct: + 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) +{ + 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); |