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agp/intel-gtt: Add intel_gmch_gtt_read_entry() 

i915 wants to read out the PTE(s) populated by the BIOS/GOP
to verify that the framebuffer is in the correct location.
Introduce intel_gmch_gtt_read_entry() that reads out the
PTE and decodes it to a somewhat abstract form. For now
we just return the dma_addr, present bit, and local memory
bit. I didn't bother with the snoop bit/etc.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250313140838.29742-4-ville.syrjala@linux.intel.com
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
This commit is contained in:
Ville Syrjälä 2025-03-13 16:08:31 +02:00
parent 9e2434f32d
commit 8f0d3618c6
2 changed files with 57 additions and 0 deletions
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55
drivers/char/agp/intel-gtt.c
View File

@ -53,6 +53,7 @@ struct intel_gtt_driver {
* of the mmio register file, that's done in the generic code. */
void (*cleanup)(void);
void (*write_entry)(dma_addr_t addr, unsigned int entry, unsigned int flags);
dma_addr_t (*read_entry)(unsigned int entry, bool *is_present, bool *is_local);
/* Flags is a more or less chipset specific opaque value.
* For chipsets that need to support old ums (non-gem) code, this
* needs to be identical to the various supported agp memory types! */
@ -336,6 +337,19 @@ static void i810_write_entry(dma_addr_t addr, unsigned int entry,
writel_relaxed(addr | pte_flags, intel_private.gtt + entry);
}
static dma_addr_t i810_read_entry(unsigned int entry,
bool *is_present, bool *is_local)
{
u32 val;
val = readl(intel_private.gtt + entry);
*is_present = val & I810_PTE_VALID;
*is_local = val & I810_PTE_LOCAL;
return val & ~0xfff;
}
static resource_size_t intel_gtt_stolen_size(void)
{
u16 gmch_ctrl;
@ -741,6 +755,19 @@ static void i830_write_entry(dma_addr_t addr, unsigned int entry,
writel_relaxed(addr | pte_flags, intel_private.gtt + entry);
}
static dma_addr_t i830_read_entry(unsigned int entry,
bool *is_present, bool *is_local)
{
u32 val;
val = readl(intel_private.gtt + entry);
*is_present = val & I810_PTE_VALID;
*is_local = false;
return val & ~0xfff;
}
bool intel_gmch_enable_gtt(void)
{
u8 __iomem *reg;
@ -878,6 +905,13 @@ void intel_gmch_gtt_insert_sg_entries(struct sg_table *st,
}
EXPORT_SYMBOL(intel_gmch_gtt_insert_sg_entries);
dma_addr_t intel_gmch_gtt_read_entry(unsigned int pg,
bool *is_present, bool *is_local)
{
return intel_private.driver->read_entry(pg, is_present, is_local);
}
EXPORT_SYMBOL(intel_gmch_gtt_read_entry);
#if IS_ENABLED(CONFIG_AGP_INTEL)
static void intel_gmch_gtt_insert_pages(unsigned int first_entry,
unsigned int num_entries,
@ -1126,6 +1160,19 @@ static void i965_write_entry(dma_addr_t addr,
writel_relaxed(addr | pte_flags, intel_private.gtt + entry);
}
static dma_addr_t i965_read_entry(unsigned int entry,
bool *is_present, bool *is_local)
{
u64 val;
val = readl(intel_private.gtt + entry);
*is_present = val & I810_PTE_VALID;
*is_local = false;
return ((val & 0xf0) << 28) | (val & ~0xfff);
}
static int i9xx_setup(void)
{
phys_addr_t reg_addr;
@ -1187,6 +1234,7 @@ static const struct intel_gtt_driver i81x_gtt_driver = {
.cleanup = i810_cleanup,
.check_flags = i830_check_flags,
.write_entry = i810_write_entry,
.read_entry = i810_read_entry,
};
static const struct intel_gtt_driver i8xx_gtt_driver = {
.gen = 2,
@ -1194,6 +1242,7 @@ static const struct intel_gtt_driver i8xx_gtt_driver = {
.setup = i830_setup,
.cleanup = i830_cleanup,
.write_entry = i830_write_entry,
.read_entry = i830_read_entry,
.dma_mask_size = 32,
.check_flags = i830_check_flags,
.chipset_flush = i830_chipset_flush,
@ -1205,6 +1254,7 @@ static const struct intel_gtt_driver i915_gtt_driver = {
.cleanup = i9xx_cleanup,
/* i945 is the last gpu to need phys mem (for overlay and cursors). */
.write_entry = i830_write_entry,
.read_entry = i830_read_entry,
.dma_mask_size = 32,
.check_flags = i830_check_flags,
.chipset_flush = i9xx_chipset_flush,
@ -1215,6 +1265,7 @@ static const struct intel_gtt_driver g33_gtt_driver = {
.setup = i9xx_setup,
.cleanup = i9xx_cleanup,
.write_entry = i965_write_entry,
.read_entry = i965_read_entry,
.dma_mask_size = 36,
.check_flags = i830_check_flags,
.chipset_flush = i9xx_chipset_flush,
@ -1225,6 +1276,7 @@ static const struct intel_gtt_driver pineview_gtt_driver = {
.setup = i9xx_setup,
.cleanup = i9xx_cleanup,
.write_entry = i965_write_entry,
.read_entry = i965_read_entry,
.dma_mask_size = 36,
.check_flags = i830_check_flags,
.chipset_flush = i9xx_chipset_flush,
@ -1235,6 +1287,7 @@ static const struct intel_gtt_driver i965_gtt_driver = {
.setup = i9xx_setup,
.cleanup = i9xx_cleanup,
.write_entry = i965_write_entry,
.read_entry = i965_read_entry,
.dma_mask_size = 36,
.check_flags = i830_check_flags,
.chipset_flush = i9xx_chipset_flush,
@ -1244,6 +1297,7 @@ static const struct intel_gtt_driver g4x_gtt_driver = {
.setup = i9xx_setup,
.cleanup = i9xx_cleanup,
.write_entry = i965_write_entry,
.read_entry = i965_read_entry,
.dma_mask_size = 36,
.check_flags = i830_check_flags,
.chipset_flush = i9xx_chipset_flush,
@ -1254,6 +1308,7 @@ static const struct intel_gtt_driver ironlake_gtt_driver = {
.setup = i9xx_setup,
.cleanup = i9xx_cleanup,
.write_entry = i965_write_entry,
.read_entry = i965_read_entry,
.dma_mask_size = 36,
.check_flags = i830_check_flags,
.chipset_flush = i9xx_chipset_flush,

2
include/drm/intel/intel-gtt.h
View File

@ -28,6 +28,8 @@ void intel_gmch_gtt_insert_sg_entries(struct sg_table *st,
unsigned int pg_start,
unsigned int flags);
void intel_gmch_gtt_clear_range(unsigned int first_entry, unsigned int num_entries);
dma_addr_t intel_gmch_gtt_read_entry(unsigned int pg,
bool *is_present, bool *is_local);
/* Special gtt memory types */
#define AGP_DCACHE_MEMORY 1