gma: Add Intel i945 (Gen3) graphics init support
Add i945G (desktop) and i945GM (mobile) generation support, modeled
after the existing G45 generation code with hardware-specific
adaptations based on the Linux i915 DRM driver and coreboot.
Key hardware differences from G45 (Gen4):
- GTT on separate PCI BAR3 (not within BAR0)
- Simple 32-bit GTT PTEs (addr[31:12] | valid[0])
- No DSPSURF register (uses DSPADDR/DSPLINOFF instead)
- Gen3 fence registers: 32-bit at split 0x2000/0x3000 addresses
- Different PLL limits (VCO 1400-2800 MHz, 96 MHz refclk)
- SDVO multiplier in DPLL register bits[7:4]
- LVDS restricted to Pipe B (pre-i965 requirement)
- CDClk: fixed 400 MHz (desktop) or GCFGC-based (mobile)
- No HDMI/DP, only VGA, LVDS, and SDVO outputs
- PCI IDs: 0x2772 (I945G), 0x27a2/0x27ae (I945GM)
TESTED with thinkpad x60: LVDS & VGA works with a linear framebuffer.
Change-Id: Ib67b3d0ee5e06df427869dce4db926ba57a80fd8
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.sourcearcade.org/c/libgfxinit/+/476
Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: Nico Huber <nico.h@gmx.de>
diff --git a/common/i945/hw-gfx-gma-plls.ads b/common/i945/hw-gfx-gma-plls.ads
new file mode 100644
index 0000000..f99a29f
--- /dev/null
+++ b/common/i945/hw-gfx-gma-plls.ads
@@ -0,0 +1,40 @@
+--
+-- Copyright (C) 2026 Arthur Heymans <arthur@aheymans.xyz>
+--
+-- This program is free software; you can redistribute it and/or modify
+-- it under the terms of the GNU General Public License as published by
+-- the Free Software Foundation; either version 2 of the License, or
+-- (at your option) any later version.
+--
+-- This program is distributed in the hope that 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.
+--
+
+private package HW.GFX.GMA.PLLs
+with
+ Abstract_State => (State with Part_Of => GMA.State)
+is
+
+ -- XXX: Types should be private (but that triggers a bug in SPARK GPL 2016)
+ type T is (Invalid_PLL, DPLL_A, DPLL_B);
+ subtype DPLLs is T range DPLL_A .. DPLL_B;
+ Invalid : constant T := Invalid_PLL;
+
+ procedure Initialize
+ with
+ Global => (Output => State);
+
+ procedure Alloc
+ (Port_Cfg : in Port_Config;
+ PLL : out T;
+ Success : out Boolean);
+
+ procedure Free (PLL : T);
+
+ procedure All_Off;
+
+ function Register_Value (PLL : T) return Word32;
+
+end HW.GFX.GMA.PLLs;