2 files changed, 175 insertions, 0 deletions
diff --git a/src/mainboard/google/brya/variants/hades/Makefile.inc b/src/mainboard/google/brya/variants/hades/Makefile.inc
index 837101ea25..81d298a708 100644
--- a/src/mainboard/google/brya/variants/hades/Makefile.inc
+++ b/src/mainboard/google/brya/variants/hades/Makefile.inc
@@ -2,3 +2,4 @@ bootblock-y += gpio.c
 romstage-y += gpio.c
 ramstage-y += gpio.c
 ramstage-y += ramstage.c
+ramstage-y += variant.c
diff --git a/src/mainboard/google/brya/variants/hades/variant.c b/src/mainboard/google/brya/variants/hades/variant.c
new file mode 100644
index 0000000000..6e980977f3
--- /dev/null
+++ b/src/mainboard/google/brya/variants/hades/variant.c
@@ -0,0 +1,174 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <acpi/acpi.h>
+#include <acpi/acpigen.h>
+#include <baseboard/variants.h>
+#include <boardid.h>
+#include <delay.h>
+#include <device/pci.h>
+#include <gpio.h>
+#include <timer.h>
+#include <types.h>
+
+#define GPU_1V2_PWR_EN		GPP_D0
+#define GPU_1V2_PG		GPP_D1
+#define GPU_1V8_PWR_EN		GPP_E11
+#define GPU_1V8_PG		GPP_E20
+#define GPU_3V3_PWR_EN		GPP_E1
+#define GPU_3V3_PG		GPP_E2
+#define NVVDD_PWR_EN		GPP_E0
+#define NVVDD_PG		GPP_E3
+#define PEXVDD_PWR_EN		GPP_E10
+#define PEXVDD_PG		GPP_E17
+#define FBVDD_PWR_EN		GPP_A19
+#define FBVDD_PG		GPP_E4
+#define GPU_PERST_L		GPP_B3
+#define GPU_ALLRAILS_PG		GPP_E5
+
+#define DEFAULT_PG_TIMEOUT_US	20000
+
+#define VGAR_BYTE_OFFSET	5
+
+/* Maximum size of PCI config space to save. */
+#define GPU_CONFIG_SAVE_SPACE_BYTES	0x100
+
+static bool gpu_powered_on;
+
+struct power_rail_sequence {
+	const char *name;
+
+	/* This is the GPIO (output) connected to the VR's enable pin. */
+	gpio_t pwr_en_gpio;
+	bool pwr_en_active_low;
+
+	/* This is the GPIO (input) connected to the VR's power-good pin. */
+	gpio_t pg_gpio;
+
+	/* Delay after sequencing this rail. */
+	unsigned int delay_ms;
+};
+
+/* In GCOFF exit order (i.e., power-on order) */
+static struct power_rail_sequence gpu_on_seq[] = {
+	{ "GPU 1.2V",		GPU_1V2_PWR_EN,	false, GPU_1V2_PG, },
+	{ "GPU 1.8V",		GPU_1V8_PWR_EN,	false, GPU_1V8_PG, },
+	{ "GPU 3.3V",		GPU_3V3_PWR_EN,	false, GPU_3V3_PG, },
+	{ "NVVDD+MSVDD",	NVVDD_PWR_EN,	false, NVVDD_PG, },
+	{ "PEXVDD",		PEXVDD_PWR_EN,	false, PEXVDD_PG, },
+	{ "FBVDD",		FBVDD_PWR_EN,	false,  FBVDD_PG, },
+};
+
+/* In GCOFF entry order (i.e., power-off order) */
+static struct power_rail_sequence gpu_off_seq[] = {
+	{ "FBVDD",		FBVDD_PWR_EN,	false,  FBVDD_PG,	0,},
+	{ "PEXVDD",		PEXVDD_PWR_EN,	false, PEXVDD_PG,	10,},
+	{ "NVVDD+MSVDD",	NVVDD_PWR_EN,	false, NVVDD_PG,	2,},
+	{ "GPU 3.3V",		GPU_3V3_PWR_EN,	false, GPU_3V3_PG,	4,},
+	{ "GPU 1.8V",		GPU_1V8_PWR_EN,	false, GPU_1V8_PG,	0,},
+	{ "GPU 1.2V",		GPU_1V2_PWR_EN,	false, GPU_1V2_PG,	0,},
+};
+
+enum rail_state {
+	RAIL_OFF = 0,
+	RAIL_ON = 1,
+};
+
+/* Assert the VR's enable pin, and wait until the VR's power-good is asserted. */
+static bool sequence_rail(const struct power_rail_sequence *seq, enum rail_state state)
+{
+	enum rail_state pwr_en_state = state;
+	bool result;
+
+	if (seq->pwr_en_active_low)
+		pwr_en_state = !pwr_en_state;
+
+	gpio_output(seq->pwr_en_gpio, pwr_en_state);
+	result = wait_us(DEFAULT_PG_TIMEOUT_US, gpio_get(seq->pg_gpio) == state) >= 0;
+	if (seq->delay_ms)
+		mdelay(seq->delay_ms);
+
+	return result;
+}
+
+static void dgpu_power_sequence_off(void)
+{
+	/* Assert reset and clear power-good */
+	gpio_output(GPU_PERST_L, 0);
+
+	/* Inform the GPU that the power is no longer good. */
+	gpio_output(GPU_ALLRAILS_PG, 0);
+
+	for (size_t i = 0; i < ARRAY_SIZE(gpu_off_seq); i++) {
+		if (!sequence_rail(&gpu_off_seq[i], RAIL_OFF)) {
+			printk(BIOS_ERR, "Failed to disable %s rail, continuing!\n",
+			       gpu_off_seq[i].name);
+		}
+	}
+}
+
+static void dgpu_power_sequence_on(void)
+{
+	/* Assert PERST# */
+	gpio_output(GPU_PERST_L, 0);
+
+	for (size_t i = 0; i < ARRAY_SIZE(gpu_on_seq); i++) {
+		if (!sequence_rail(&gpu_on_seq[i], RAIL_ON)) {
+			printk(BIOS_ERR, "Failed to enable %s rail, sequencing back down!\n",
+			       gpu_on_seq[i].name);
+
+			/* If an error occurred, then perform the power-off sequence and
+			   return early to avoid setting GPU_ALLRAILS_PG and PERST_L. */
+			dgpu_power_sequence_off();
+			return;
+		}
+	}
+
+	/* Set power-good and release PERST# */
+	gpio_output(GPU_ALLRAILS_PG, 1);
+	mdelay(1);
+	gpio_output(GPU_PERST_L, 1);
+
+	printk(BIOS_INFO, "Sequenced GPU successfully\n");
+	mdelay(1);
+
+	gpu_powered_on = true;
+}
+
+void variant_init(void)
+{
+	if (acpi_is_wakeup_s3())
+		return;
+
+	dgpu_power_sequence_on();
+}
+
+/*
+ * Pass the specific GPIO names
+ */
+void variant_fill_ssdt(const struct device *dev)
+{
+	const int nvvdd_pg_gpio = NVVDD_PG;
+	const int gpu_1v8_en_gpio = GPU_1V8_PWR_EN;
+	acpigen_write_scope("\\_SB.PCI0.PEG0.PEGP");
+	acpigen_write_method("_INI", 0);
+	acpigen_write_store_int_to_namestr(nvvdd_pg_gpio, "NVPG");
+	acpigen_write_store_int_to_namestr(gpu_1v8_en_gpio, "GPEN");
+	acpigen_write_method_end();
+	acpigen_write_scope_end();
+}
+
+void variant_finalize(void)
+{
+	/*
+	 * Currently the `pch_pirq_init()` function in lpc_lib.c will program
+	 * PIRQ IRQs for all PCI devices discovered during enumeration. This may
+	 * not be correct for all devices, and causes strange behavior with the
+	 * Nvidia dGPU; it will start out with IRQ 11 and then after a
+	 * suspend/resume cycle, it will get programmed back to 16, so the Linux
+	 * kernel must be doing some IRQ sanitization at some point.  To fix
+	 * this anomaly, explicitly program the IRQ to 16 (which we know is what
+	 * IRQ it will eventually take).
+	*/
+	const struct device *dgpu = DEV_PTR(dgpu);
+	pci_write_config8(dgpu, PCI_INTERRUPT_LINE, 16);
+}