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x86, AMD IOMMU: add comments to the initialization code 

This patch adds some comments to the AMD IOMMU initialization code to increase
its readability.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Cc: iommu@lists.linux-foundation.org
Cc: bhavna.sarathy@amd.com
Cc: robert.richter@amd.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
hifive-unleashed-5.1
Joerg Roedel 2008-07-11 17:14:21 +02:00 committed by Ingo Molnar
parent 5694703f14
commit b65233a9c1
1 changed files with 206 additions and 8 deletions
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214
arch/x86/kernel/amd_iommu_init.c
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@ -71,6 +71,17 @@
#define ACPI_DEVFLAG_LINT1 0x80
#define ACPI_DEVFLAG_ATSDIS 0x10000000
/*
* ACPI table definitions
*
* These data structures are laid over the table to parse the important values
* out of it.
*/
/*
* structure describing one IOMMU in the ACPI table. Typically followed by one
* or more ivhd_entrys.
*/
struct ivhd_header {
u8 type;
u8 flags;
@ -83,6 +94,10 @@ struct ivhd_header {
u32 reserved;
} __attribute__((packed));
/*
* A device entry describing which devices a specific IOMMU translates and
* which requestor ids they use.
*/
struct ivhd_entry {
u8 type;
u16 devid;
@ -90,6 +105,10 @@ struct ivhd_entry {
u32 ext;
} __attribute__((packed));
/*
* An AMD IOMMU memory definition structure. It defines things like exclusion
* ranges for devices and regions that should be unity mapped.
*/
struct ivmd_header {
u8 type;
u8 flags;
@ -103,22 +122,66 @@ struct ivmd_header {
static int __initdata amd_iommu_detected;
u16 amd_iommu_last_bdf;
struct list_head amd_iommu_unity_map;
unsigned amd_iommu_aperture_order = 26;
int amd_iommu_isolate;
u16 amd_iommu_last_bdf; /* largest PCI device id we have
to handle */
struct list_head amd_iommu_unity_map; /* a list of required unity mappings
we find in ACPI */
unsigned amd_iommu_aperture_order = 26; /* size of aperture in power of 2 */
int amd_iommu_isolate; /* if 1, device isolation is enabled */
struct list_head amd_iommu_list;
struct list_head amd_iommu_list; /* list of all AMD IOMMUs in the
system */
/*
* Pointer to the device table which is shared by all AMD IOMMUs
* it is indexed by the PCI device id or the HT unit id and contains
* information about the domain the device belongs to as well as the
* page table root pointer.
*/
struct dev_table_entry *amd_iommu_dev_table;
/*
* The alias table is a driver specific data structure which contains the
* mappings of the PCI device ids to the actual requestor ids on the IOMMU.
* More than one device can share the same requestor id.
*/
u16 *amd_iommu_alias_table;
/*
* The rlookup table is used to find the IOMMU which is responsible
* for a specific device. It is also indexed by the PCI device id.
*/
struct amd_iommu **amd_iommu_rlookup_table;
/*
* The pd table (protection domain table) is used to find the protection domain
* data structure a device belongs to. Indexed with the PCI device id too.
*/
struct protection_domain **amd_iommu_pd_table;
/*
* AMD IOMMU allows up to 2^16 differend protection domains. This is a bitmap
* to know which ones are already in use.
*/
unsigned long *amd_iommu_pd_alloc_bitmap;
static u32 dev_table_size;
static u32 alias_table_size;
static u32 rlookup_table_size;
static u32 dev_table_size; /* size of the device table */
static u32 alias_table_size; /* size of the alias table */
static u32 rlookup_table_size; /* size if the rlookup table */
/****************************************************************************
*
* AMD IOMMU MMIO register space handling functions
*
* These functions are used to program the IOMMU device registers in
* MMIO space required for that driver.
*
****************************************************************************/
/*
* This function set the exclusion range in the IOMMU. DMA accesses to the
* exclusion range are passed through untranslated
*/
static void __init iommu_set_exclusion_range(struct amd_iommu *iommu)
{
u64 start = iommu->exclusion_start & PAGE_MASK;
@ -137,6 +200,7 @@ static void __init iommu_set_exclusion_range(struct amd_iommu *iommu)
&entry, sizeof(entry));
}
/* Programs the physical address of the device table into the IOMMU hardware */
static void __init iommu_set_device_table(struct amd_iommu *iommu)
{
u32 entry;
@ -149,6 +213,7 @@ static void __init iommu_set_device_table(struct amd_iommu *iommu)
&entry, sizeof(entry));
}
/* Generic functions to enable/disable certain features of the IOMMU. */
static void __init iommu_feature_enable(struct amd_iommu *iommu, u8 bit)
{
u32 ctrl;
@ -167,6 +232,7 @@ static void __init iommu_feature_disable(struct amd_iommu *iommu, u8 bit)
writel(ctrl, iommu->mmio_base + MMIO_CONTROL_OFFSET);
}
/* Function to enable the hardware */
void __init iommu_enable(struct amd_iommu *iommu)
{
printk(KERN_INFO "AMD IOMMU: Enabling IOMMU at ");
@ -176,6 +242,10 @@ void __init iommu_enable(struct amd_iommu *iommu)
iommu_feature_enable(iommu, CONTROL_IOMMU_EN);
}
/*
* mapping and unmapping functions for the IOMMU MMIO space. Each AMD IOMMU in
* the system has one.
*/
static u8 * __init iommu_map_mmio_space(u64 address)
{
u8 *ret;
@ -199,6 +269,19 @@ static void __init iommu_unmap_mmio_space(struct amd_iommu *iommu)
release_mem_region(iommu->mmio_phys, MMIO_REGION_LENGTH);
}
/****************************************************************************
*
* The functions below belong to the first pass of AMD IOMMU ACPI table
* parsing. In this pass we try to find out the highest device id this
* code has to handle. Upon this information the size of the shared data
* structures is determined later.
*
****************************************************************************/
/*
* This function reads the last device id the IOMMU has to handle from the PCI
* capability header for this IOMMU
*/
static int __init find_last_devid_on_pci(int bus, int dev, int fn, int cap_ptr)
{
u32 cap;
@ -209,6 +292,10 @@ static int __init find_last_devid_on_pci(int bus, int dev, int fn, int cap_ptr)
return 0;
}
/*
* After reading the highest device id from the IOMMU PCI capability header
* this function looks if there is a higher device id defined in the ACPI table
*/
static int __init find_last_devid_from_ivhd(struct ivhd_header *h)
{
u8 *p = (void *)h, *end = (void *)h;
@ -229,6 +316,7 @@ static int __init find_last_devid_from_ivhd(struct ivhd_header *h)
case IVHD_DEV_RANGE_END:
case IVHD_DEV_ALIAS:
case IVHD_DEV_EXT_SELECT:
/* all the above subfield types refer to device ids */
UPDATE_LAST_BDF(dev->devid);
break;
default:
@ -242,6 +330,11 @@ static int __init find_last_devid_from_ivhd(struct ivhd_header *h)
return 0;
}
/*
* Iterate over all IVHD entries in the ACPI table and find the highest device
* id which we need to handle. This is the first of three functions which parse
* the ACPI table. So we check the checksum here.
*/
static int __init find_last_devid_acpi(struct acpi_table_header *table)
{
int i;
@ -277,6 +370,20 @@ static int __init find_last_devid_acpi(struct acpi_table_header *table)
return 0;
}
/****************************************************************************
*
* The following functions belong the the code path which parses the ACPI table
* the second time. In this ACPI parsing iteration we allocate IOMMU specific
* data structures, initialize the device/alias/rlookup table and also
* basically initialize the hardware.
*
****************************************************************************/
/*
* Allocates the command buffer. This buffer is per AMD IOMMU. We can
* write commands to that buffer later and the IOMMU will execute them
* asynchronously
*/
static u8 * __init alloc_command_buffer(struct amd_iommu *iommu)
{
u8 *cmd_buf = (u8 *)__get_free_pages(GFP_KERNEL,
@ -307,6 +414,7 @@ static void __init free_command_buffer(struct amd_iommu *iommu)
get_order(CMD_BUFFER_SIZE));
}
/* sets a specific bit in the device table entry. */
static void set_dev_entry_bit(u16 devid, u8 bit)
{
int i = (bit >> 5) & 0x07;
@ -315,6 +423,10 @@ static void set_dev_entry_bit(u16 devid, u8 bit)
amd_iommu_dev_table[devid].data[i] |= (1 << _bit);
}
/*
* This function takes the device specific flags read from the ACPI
* table and sets up the device table entry with that information
*/
static void __init set_dev_entry_from_acpi(u16 devid, u32 flags, u32 ext_flags)
{
if (flags & ACPI_DEVFLAG_INITPASS)
@ -333,11 +445,16 @@ static void __init set_dev_entry_from_acpi(u16 devid, u32 flags, u32 ext_flags)
set_dev_entry_bit(devid, DEV_ENTRY_LINT1_PASS);
}
/* Writes the specific IOMMU for a device into the rlookup table */
static void __init set_iommu_for_device(struct amd_iommu *iommu, u16 devid)
{
amd_iommu_rlookup_table[devid] = iommu;
}
/*
* Reads the device exclusion range from ACPI and initialize IOMMU with
* it
*/
static void __init set_device_exclusion_range(u16 devid, struct ivmd_header *m)
{
struct amd_iommu *iommu = amd_iommu_rlookup_table[devid];
@ -346,12 +463,22 @@ static void __init set_device_exclusion_range(u16 devid, struct ivmd_header *m)
return;
if (iommu) {
/*
* We only can configure exclusion ranges per IOMMU, not
* per device. But we can enable the exclusion range per
* device. This is done here
*/
set_dev_entry_bit(m->devid, DEV_ENTRY_EX);
iommu->exclusion_start = m->range_start;
iommu->exclusion_length = m->range_length;
}
}
/*
* This function reads some important data from the IOMMU PCI space and
* initializes the driver data structure with it. It reads the hardware
* capabilities and the first/last device entries
*/
static void __init init_iommu_from_pci(struct amd_iommu *iommu)
{
int bus = PCI_BUS(iommu->devid);
@ -367,6 +494,10 @@ static void __init init_iommu_from_pci(struct amd_iommu *iommu)
iommu->last_device = DEVID(MMIO_GET_BUS(range), MMIO_GET_LD(range));
}
/*
* Takes a pointer to an AMD IOMMU entry in the ACPI table and
* initializes the hardware and our data structures with it.
*/
static void __init init_iommu_from_acpi(struct amd_iommu *iommu,
struct ivhd_header *h)
{
@ -467,6 +598,7 @@ static void __init init_iommu_from_acpi(struct amd_iommu *iommu,
}
}
/* Initializes the device->iommu mapping for the driver */
static int __init init_iommu_devices(struct amd_iommu *iommu)
{
u16 i;
@ -494,6 +626,11 @@ static void __init free_iommu_all(void)
}
}
/*
* This function clues the initialization function for one IOMMU
* together and also allocates the command buffer and programs the
* hardware. It does NOT enable the IOMMU. This is done afterwards.
*/
static int __init init_iommu_one(struct amd_iommu *iommu, struct ivhd_header *h)
{
spin_lock_init(&iommu->lock);
@ -521,6 +658,10 @@ static int __init init_iommu_one(struct amd_iommu *iommu, struct ivhd_header *h)
return 0;
}
/*
* Iterates over all IOMMU entries in the ACPI table, allocates the
* IOMMU structure and initializes it with init_iommu_one()
*/
static int __init init_iommu_all(struct acpi_table_header *table)
{
u8 *p = (u8 *)table, *end = (u8 *)table;
@ -555,6 +696,14 @@ static int __init init_iommu_all(struct acpi_table_header *table)
return 0;
}
/****************************************************************************
*
* The next functions belong to the third pass of parsing the ACPI
* table. In this last pass the memory mapping requirements are
* gathered (like exclusion and unity mapping reanges).
*
****************************************************************************/
static void __init free_unity_maps(void)
{
struct unity_map_entry *entry, *next;
@ -565,6 +714,7 @@ static void __init free_unity_maps(void)
}
}
/* called when we find an exclusion range definition in ACPI */
static int __init init_exclusion_range(struct ivmd_header *m)
{
int i;
@ -588,6 +738,7 @@ static int __init init_exclusion_range(struct ivmd_header *m)
return 0;
}
/* called for unity map ACPI definition */
static int __init init_unity_map_range(struct ivmd_header *m)
{
struct unity_map_entry *e = 0;
@ -619,6 +770,7 @@ static int __init init_unity_map_range(struct ivmd_header *m)
return 0;
}
/* iterates over all memory definitions we find in the ACPI table */
static int __init init_memory_definitions(struct acpi_table_header *table)
{
u8 *p = (u8 *)table, *end = (u8 *)table;
@ -642,6 +794,10 @@ static int __init init_memory_definitions(struct acpi_table_header *table)
return 0;
}
/*
* This function finally enables all IOMMUs found in the system after
* they have been initialized
*/
static void __init enable_iommus(void)
{
struct amd_iommu *iommu;
@ -678,6 +834,34 @@ static struct sys_device device_amd_iommu = {
.cls = &amd_iommu_sysdev_class,
};
/*
* This is the core init function for AMD IOMMU hardware in the system.
* This function is called from the generic x86 DMA layer initialization
* code.
*
* This function basically parses the ACPI table for AMD IOMMU (IVRS)
* three times:
*
* 1 pass) Find the highest PCI device id the driver has to handle.
* Upon this information the size of the data structures is
* determined that needs to be allocated.
*
* 2 pass) Initialize the data structures just allocated with the
* information in the ACPI table about available AMD IOMMUs
* in the system. It also maps the PCI devices in the
* system to specific IOMMUs
*
* 3 pass) After the basic data structures are allocated and
* initialized we update them with information about memory
* remapping requirements parsed out of the ACPI table in
* this last pass.
*
* After that the hardware is initialized and ready to go. In the last
* step we do some Linux specific things like registering the driver in
* the dma_ops interface and initializing the suspend/resume support
* functions. Finally it prints some information about AMD IOMMUs and
* the driver state and enables the hardware.
*/
int __init amd_iommu_init(void)
{
int i, ret = 0;
@ -821,6 +1005,13 @@ free:
goto out;
}
/****************************************************************************
*
* Early detect code. This code runs at IOMMU detection time in the DMA
* layer. It just looks if there is an IVRS ACPI table to detect AMD
* IOMMUs
*
****************************************************************************/
static int __init early_amd_iommu_detect(struct acpi_table_header *table)
{
return 0;
@ -841,6 +1032,13 @@ void __init amd_iommu_detect(void)
}
}
/****************************************************************************
*
* Parsing functions for the AMD IOMMU specific kernel command line
* options.
*
****************************************************************************/
static int __init parse_amd_iommu_options(char *str)
{
for (; *str; ++str) {