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