[PATCH V9 1/8] ACPI: I/O Remapping Table (IORT) initial support
Tomasz Nowicki
tn at semihalf.com
Tue Sep 6 00:24:35 PDT 2016
Hi Rafael,
On 05.09.2016 22:29, Rafael J. Wysocki wrote:
> On Mon, Sep 5, 2016 at 10:05 PM, Tomasz Nowicki <tn at semihalf.com> wrote:
>> IORT shows representation of IO topology for ARM based systems.
>> It describes how various components are connected together on
>> parent-child basis e.g. PCI RC -> SMMU -> ITS. Also see IORT spec.
>> http://infocenter.arm.com/help/topic/com.arm.doc.den0049b/DEN0049B_IO_Remapping_Table.pdf
>>
>> Initial support allows to detect IORT table presence and save its
>> root pointer obtained through acpi_get_table(). The pointer validity
>> depends on acpi_gbl_permanent_mmap because if acpi_gbl_permanent_mmap
>> is not set while using IORT nodes we would dereference unmapped pointers.
>>
>> For the aforementioned reason call iort_table_detect() from acpi_init()
>> which guarantees acpi_gbl_permanent_mmap to be set at that point.
>>
>> Add generic helpers which are helpful for scanning and retrieving
>> information from IORT table content. List of the most important helpers:
>> - iort_find_dev_node() finds IORT node for a given device
>> - iort_node_map_rid() maps device RID and returns IORT node which provides
>> final translation
>>
>> IORT support is placed under drivers/acpi/arm64/ new directory due to its
>> ARM64 specific nature. The code there is considered only for ARM64.
>> The long term plan is to keep all ARM64 specific tables support
>> in this place e.g. GTDT table.
>>
>> Signed-off-by: Tomasz Nowicki <tn at semihalf.com>
>> Reviewed-by: Hanjun Guo <hanjun.guo at linaro.org>
>> Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>
>
> Some cosmetic stuff below.
>
[...]
>> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
>> new file mode 100644
>> index 0000000..82d5e7d
>> --- /dev/null
>> +++ b/drivers/acpi/arm64/iort.c
>> @@ -0,0 +1,221 @@
>> +/*
>> + * Copyright (C) 2016, Semihalf
>> + * Author: Tomasz Nowicki <tn at semihalf.com>
>> + *
>> + * This program is free software; you can redistribute it and/or modify it
>> + * under the terms and conditions of the GNU General Public License,
>> + * version 2, as published by the Free Software Foundation.
>> + *
>> + * This program is distributed in the hope it will be useful, but WITHOUT
>> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
>> + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
>> + * more details.
>> + *
>> + * This file implements early detection/parsing of I/O mapping
>> + * reported to OS through firmware via I/O Remapping Table (IORT)
>> + * IORT document number: ARM DEN 0049A
>> + */
>> +
>> +#define pr_fmt(fmt) "ACPI: IORT: " fmt
>> +
>> +#include <linux/iort.h>
>
> Do we need a separate header file for this?
IMO yes. It's well isolated functionality and more will be added in
patch 2 and IOMMU support by Lorenzo. Also, it's the same convention as
for DMAR support.
>
>> +#include <linux/kernel.h>
>> +#include <linux/pci.h>
>> +
>> +typedef acpi_status (*iort_find_node_callback)
>> + (struct acpi_iort_node *node, void *context);
>> +
>> +/* Root pointer to the mapped IORT table */
>> +static struct acpi_table_header *iort_table;
>> +
>> +static struct acpi_iort_node *
>> +iort_scan_node(enum acpi_iort_node_type type,
>
> Please do not break function headers like this. Specifically, the
> return type and the name should be located in the same line.
OK
>
>> + iort_find_node_callback callback, void *context)
>> +{
>> + struct acpi_iort_node *iort_node, *iort_end;
>> + struct acpi_table_iort *iort;
>> + int i;
>> +
>> + if (!iort_table)
>> + return NULL;
>> +
>> + /* Get the first IORT node */
>> + iort = (struct acpi_table_iort *)iort_table;
>> + iort_node = ACPI_ADD_PTR(struct acpi_iort_node, iort,
>> + iort->node_offset);
>> + iort_end = ACPI_ADD_PTR(struct acpi_iort_node, iort_table,
>> + iort_table->length);
>> +
>> + for (i = 0; i < iort->node_count; i++) {
>> + if (WARN_TAINT(iort_node >= iort_end, TAINT_FIRMWARE_WORKAROUND,
>> + "IORT node pointer overflows, bad table!\n"))
>> + return NULL;
>> +
>> + if (iort_node->type == type) {
>> + if (ACPI_SUCCESS(callback(iort_node, context)))
>> + return iort_node;
>
> It's better to write this as
>
> if (iort_node->type == type && ACPI_SUCCESS(callback(iort_node, context))
> return iort_node;
OK
>
>> + }
>> +
>> + iort_node = ACPI_ADD_PTR(struct acpi_iort_node, iort_node,
>> + iort_node->length);
>> + }
>> +
>> + return NULL;
>> +}
>> +
>> +static acpi_status
>> +iort_match_node_callback(struct acpi_iort_node *node, void *context)
>> +{
>> + struct device *dev = context;
>> +
>> + switch (node->type) {
>> + case ACPI_IORT_NODE_NAMED_COMPONENT: {
>> + struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
>> + struct acpi_device *adev = to_acpi_device_node(dev->fwnode);
>> + struct acpi_iort_named_component *ncomp;
>> +
>> + if (!adev)
>> + break;
>> +
>> + ncomp = (struct acpi_iort_named_component *)node->node_data;
>> +
>> + if (ACPI_FAILURE(acpi_get_name(adev->handle,
>> + ACPI_FULL_PATHNAME, &buffer))) {
>> + dev_warn(dev, "Can't get device full path name\n");
>
> I'd switch the branches so that the one to be executed on success goes first.
>
> Also consider using acpi_status variables for things like this.
>
> status = acpi_get_name(adev->handle, ACPI_FULL_PATHNAME, &buffer);
> if (ACPI_SUCCESS(status)) {
>
> is much easier to follow than what you are doing here.
Agree, actually I rewrite this function as follow:
static acpi_status iort_match_node_callback(struct acpi_iort_node *node,
void *context)
{
struct device *dev = context;
acpi_status status = AE_NOT_FOUND;
switch (node->type) {
case ACPI_IORT_NODE_NAMED_COMPONENT: {
struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER, NULL };
struct acpi_device *adev = to_acpi_device_node(dev->fwnode);
struct acpi_iort_named_component *ncomp;
if (!adev)
break;
status = acpi_get_name(adev->handle, ACPI_FULL_PATHNAME, &buf);
if (ACPI_FAILURE(status)) {
dev_warn(dev, "Can't get device full path name\n");
break;
}
ncomp = (struct acpi_iort_named_component *)node->node_data;
if (!strcmp(ncomp->device_name, buf.pointer))
status = AE_OK;
acpi_os_free(buf.pointer);
break;
}
case ACPI_IORT_NODE_PCI_ROOT_COMPLEX: {
struct acpi_iort_root_complex *pci_rc;
struct pci_bus *bus;
bus = to_pci_bus(dev);
pci_rc = (struct acpi_iort_root_complex *)node->node_data;
/*
* It is assumed that PCI segment numbers maps one-to-one
* with root complexes. Each segment number can represent only
* one root complex.
*/
if (pci_rc->pci_segment_number == pci_domain_nr(bus))
status = AE_OK;
break;
}
}
return status;
}
>
>> + } else {
>> + int match;
>> +
>> + match = !strcmp(ncomp->device_name, buffer.pointer);
>> + acpi_os_free(buffer.pointer);
>> +
>> + if (match)
>> + return AE_OK;
>> + }
>> +
>> + break;
>> + }
>> + case ACPI_IORT_NODE_PCI_ROOT_COMPLEX: {
>
> What is the brace for?
To create namespace for below local variables. The same for
ACPI_IORT_NODE_NAMED_COMPONENT case.
>
>> + struct acpi_iort_root_complex *pci_rc;
>> + struct pci_bus *bus;
>> +
>> + bus = to_pci_bus(dev);
>> + pci_rc = (struct acpi_iort_root_complex *)node->node_data;
>> +
>> + /*
>> + * It is assumed that PCI segment numbers maps one-to-one
>> + * with root complexes. Each segment number can represent only
>> + * one root complex.
>> + */
>> + if (pci_rc->pci_segment_number == pci_domain_nr(bus))
>> + return AE_OK;
>> +
>> + break;
>> + }
>> + }
>> +
>> + return AE_NOT_FOUND;
>> +}
>> +
[...]
>> diff --git a/include/linux/iort.h b/include/linux/iort.h
>> new file mode 100644
>> index 0000000..f4d5d45
>> --- /dev/null
>> +++ b/include/linux/iort.h
>
> If the new file header is necessary, it should be called acpi_iort.h IMO.
OK
Thanks,
Tomasz
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