[PATCH v5 03/25] soundwire: amd: add pad ctrl helpers for D0/D3 PM transitions

[Vijendar Mukunda]

During POWER_OFF_MODE clock stop the SoundWire clock is expected to
transition High to Low cleanly. On some OEM platforms based on
ACP 7.0/7.1/7.2, a transient High pulse is observed after the initial
Low; the clock briefly follows a High -> Low -> High -> Low sequence
(High lasting a few milliseconds) instead of the expected High -> Low.
This spurious High edge interferes with wake interrupt detection,
causing wake events to be silently missed.

Hardware team analysis identified that the pad keeper, pulldown,
SCHMEN control and output-enable registers must be programmed as a
coordinated sequence during D3 entry and D0 re-entry to suppress the
transient bounce and restore the pads correctly on resume.

Introduce amd_sdw_pad_ctrl() to program PAD_KEEPER_EN,
PAD_PULLDOWN_CTRL, PAD_SCHMEN_CTRL and PAD_DISABLE_OE_CTRL in a
single call for D0 entry (enable=true) or D3 entry (enable=false).
Introduce amd_sdw_oe_ctrl() as a lighter helper that only toggles OE.
Introduce amd_sdw_pad_ctrl_supported() to consolidate the ACP revision
check; both helpers use it in place of duplicate switch statements.

Both helpers apply only to ACP 7.0/7.1/7.2; ACP 6.3 returns without
error and unknown revisions emit a dev_err and return.

Wire amd_sdw_pad_ctrl() into amd_suspend() and amd_resume_runtime().
Wire amd_sdw_oe_ctrl() into amd_suspend_runtime() to disable OE while
leaving keeper and schmen enabled; pads remain capable of detecting wake
events when wake is armed.

Fixes: 829c3e1cb4a3 ("soundwire: amd: set device power state during suspend/resume sequence")
Signed-off-by: Vijendar Mukunda <Vijendar.Mukunda@xxxxxxx>
---
 drivers/soundwire/amd_manager.c | 108 ++++++++++++++++++++++++++++++++
 1 file changed, 108 insertions(+)

diff --git a/drivers/soundwire/amd_manager.c b/drivers/soundwire/amd_manager.c
index a3316efdf8ac..b21691652490 100644
--- a/drivers/soundwire/amd_manager.c
+++ b/drivers/soundwire/amd_manager.c
@@ -152,6 +152,104 @@ static int amd_deinit_sdw_manager(struct amd_sdw_manager *amd_manager)
 	return amd_disable_sdw_manager(amd_manager);
 }
 
+static void __amd_sdw_oe_update(struct amd_sdw_manager *amd_manager,
+				u32 mask, bool enable)
+{
+	amd_updatel(amd_manager->acp_mmio, ACP_PAD_DISABLE_OE_CTRL,
+		    mask, enable ? 0 : mask);
+}
+
+static bool amd_sdw_pad_ctrl_supported(struct amd_sdw_manager *amd_manager)
+{
+	switch (amd_manager->acp_rev) {
+	case ACP70_PCI_REV_ID:
+	case ACP71_PCI_REV_ID:
+	case ACP72_PCI_REV_ID:
+		return true;
+	case ACP63_PCI_REV_ID:
+		return false;
+	default:
+		dev_err(amd_manager->dev, "unknown ACP revision 0x%x\n",
+			amd_manager->acp_rev);
+		return false;
+	}
+}
+
+static void amd_sdw_oe_ctrl(struct amd_sdw_manager *amd_manager, bool enable)
+{
+	u32 mask;
+
+	if (!amd_sdw_pad_ctrl_supported(amd_manager))
+		return;
+
+	switch (amd_manager->instance) {
+	case ACP_SDW0:
+		mask = AMD_SDW0_PAD_OE_CTRL_MASK;
+		break;
+	case ACP_SDW1:
+		mask = AMD_SDW1_PAD_OE_CTRL_MASK;
+		break;
+	default:
+		dev_err(amd_manager->dev, "invalid SDW instance %d\n",
+			amd_manager->instance);
+		return;
+	}
+
+	mutex_lock(amd_manager->acp_sdw_lock);
+	__amd_sdw_oe_update(amd_manager, mask, enable);
+	mutex_unlock(amd_manager->acp_sdw_lock);
+}
+
+static void amd_sdw_pad_ctrl(struct amd_sdw_manager *amd_manager, bool enable)
+{
+	u32 keeper_mask, pulldown_mask, schmen_mask, oe_mask;
+
+	if (!amd_sdw_pad_ctrl_supported(amd_manager))
+		return;
+
+	switch (amd_manager->instance) {
+	case ACP_SDW0:
+		keeper_mask   = AMD_SDW0_PAD_KEEPER_EN_MASK;
+		pulldown_mask = AMD_SDW0_PAD_PULLDOWN_MASK;
+		schmen_mask   = AMD_SDW0_PAD_SCHMEN_MASK;
+		oe_mask       = AMD_SDW0_PAD_OE_CTRL_MASK;
+		break;
+	case ACP_SDW1:
+		keeper_mask   = AMD_SDW1_PAD_KEEPER_EN_MASK;
+		pulldown_mask = AMD_SDW1_PAD_PULLDOWN_MASK;
+		schmen_mask   = AMD_SDW1_PAD_SCHMEN_MASK;
+		oe_mask       = AMD_SDW1_PAD_OE_CTRL_MASK;
+		break;
+	default:
+		dev_err(amd_manager->dev, "invalid SDW instance %d\n",
+			amd_manager->instance);
+		return;
+	}
+
+	mutex_lock(amd_manager->acp_sdw_lock);
+	if (enable) {
+		/* D0: set keeper, clear pulldown, set schmen */
+		amd_updatel(amd_manager->acp_mmio, ACP_SW_PAD_KEEPER_EN,
+			    keeper_mask, keeper_mask);
+		amd_updatel(amd_manager->acp_mmio, ACP_PAD_PULLDOWN_CTRL,
+			    pulldown_mask, 0);
+		amd_updatel(amd_manager->acp_mmio, ACP_PAD_SCHMEN_CTRL,
+			    schmen_mask, schmen_mask);
+	} else {
+		/* D3: clear keeper, set pulldown, clear schmen */
+		amd_updatel(amd_manager->acp_mmio, ACP_SW_PAD_KEEPER_EN,
+			    keeper_mask, 0);
+		amd_updatel(amd_manager->acp_mmio, ACP_PAD_PULLDOWN_CTRL,
+			    pulldown_mask, pulldown_mask);
+		amd_updatel(amd_manager->acp_mmio, ACP_PAD_SCHMEN_CTRL,
+			    schmen_mask, 0);
+	}
+
+	/* enable OE on D0 (clear disable bits), disable OE on D3 (set them) */
+	__amd_sdw_oe_update(amd_manager, oe_mask, enable);
+	mutex_unlock(amd_manager->acp_sdw_lock);
+}
+
 static void amd_sdw_set_frameshape(struct amd_sdw_manager *amd_manager)
 {
 	u32 frame_size;
@@ -1319,6 +1417,8 @@ static int __maybe_unused amd_suspend(struct device *dev)
 		ret = amd_deinit_sdw_manager(amd_manager);
 		if (ret)
 			return ret;
+		/* System suspend: tear down all pads */
+		amd_sdw_pad_ctrl(amd_manager, false);
 	}
 	if (amd_manager->acp_rev >= ACP70_PCI_REV_ID) {
 		ret = amd_sdw_set_device_state(amd_manager, AMD_SDW_DEVICE_STATE_D3);
@@ -1363,6 +1463,13 @@ static int __maybe_unused amd_suspend_runtime(struct device *dev)
 		ret = amd_deinit_sdw_manager(amd_manager);
 		if (ret)
 			return ret;
+		/*
+		 * For ACP 7.0/7.1/7.2: disable OE only; keeper and schmen remain
+		 * enabled unconditionally so that wake-capable devices can detect
+		 * wake events if wake is armed.
+		 * For ACP 6.3 this call is a no-op.
+		 */
+		amd_sdw_oe_ctrl(amd_manager, false);
 	}
 	if (amd_manager->acp_rev >= ACP70_PCI_REV_ID) {
 		ret = amd_sdw_set_device_state(amd_manager, AMD_SDW_DEVICE_STATE_D3);
@@ -1403,6 +1510,7 @@ static int __maybe_unused amd_resume_runtime(struct device *dev)
 				return ret;
 		}
 	} else if (amd_manager->power_mode_mask & AMD_SDW_POWER_OFF_MODE) {
+		amd_sdw_pad_ctrl(amd_manager, true);
 		writel(0x00, amd_manager->acp_mmio + ACP_SW_WAKE_EN(amd_manager->instance));
 		if (amd_manager->acp_rev >= ACP70_PCI_REV_ID) {
 			ret = amd_sdw_host_wake_enable(amd_manager, false);
-- 
2.53.0