gxfb/lxfb: detect framebuffer size using an MSR if VSA2 isn't available

If there's no VSA2 (ie, if we're using tinybios or OpenFirmware), use the
GLIU's P2D Range Offset Descriptor to determine how much memory we have
available for the framebuffer.

Originally based on a patch by Jordan Crouse.  Tested with OpenFirmware;
Pascal informs me that tinybios has a stub that fills in P2D_RO0.

Signed-off-by: Andres Salomon <[email protected]>
Cc: Jordan Crouse <[email protected]>
Cc: "Antonino A. Daplas" <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Andres Salomon 2008-04-28 02:15:30 -07:00 • committed by Linus Torvalds
commit fd96795630
3 changed files with 35 additions and 1 deletions

View file

@ -25,7 +25,23 @@ unsigned int gx_frame_buffer_size(void)
{
unsigned int val;
/* FB size is reported by a virtual register */
if (!geode_has_vsa2()) {
uint32_t hi, lo;
/* The number of pages is (PMAX - PMIN)+1 */
rdmsr(MSR_GLIU_P2D_RO0, lo, hi);
/* PMAX */
val = ((hi & 0xff) << 12) | ((lo & 0xfff00000) >> 20);
/* PMIN */
val -= (lo & 0x000fffff);
val += 1;
/* The page size is 4k */
return (val << 12);
}
/* FB size can be obtained from the VSA II */
/* Virtual register class = 0x02 */
/* VG_MEM_SIZE(512Kb units) = 0x00 */

View file

@ -329,6 +329,22 @@ unsigned int lx_framebuffer_size(void)
{
unsigned int val;
if (!geode_has_vsa2()) {
uint32_t hi, lo;
/* The number of pages is (PMAX - PMIN)+1 */
rdmsr(MSR_GLIU_P2D_RO0, lo, hi);
/* PMAX */
val = ((hi & 0xff) << 12) | ((lo & 0xfff00000) >> 20);
/* PMIN */
val -= (lo & 0x000fffff);
val += 1;
/* The page size is 4k */
return (val << 12);
}
/* The frame buffer size is reported by a VSM in VSA II */
/* Virtual Register Class = 0x02 */
/* VG_MEM_SIZE (1MB units) = 0x00 */