linux-kernel - [PATCH 4/4] platform/x86/amd: pmc: Add an extra STB message for entering s2idle

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Date:   Sun, 28 Aug 2022 17:21:21 -0500
From:   Mario Limonciello <mario.limonciello@....com>
To:     <mario.limonciello@....com>,
        Shyam Sundar S K <Shyam-sundar.S-k@....com>
CC:     <rafael@...nel.org>, <hdegoede@...hat.com>,
        Mark Gross <markgross@...nel.org>,
        <platform-driver-x86@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH 4/4] platform/x86/amd: pmc: Add an extra STB message for entering s2idle

The `enter` callback is run right before the cores are put into HLT.
This will allow checking synchronization problems with other software
that writes into the STB.

Signed-off-by: Mario Limonciello <mario.limonciello@....com>
---
In this patch it's intentional that `int rc` isn't directly set to
`amd_pmc_write_stb()` so that if a workaround is added related to this
in the future it can come before the STB message about entering s2idle
without having to change either of those lines.

 drivers/platform/x86/amd/pmc.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/platform/x86/amd/pmc.c b/drivers/platform/x86/amd/pmc.c
index fba42036682d..0f1b5b1a0bb8 100644
--- a/drivers/platform/x86/amd/pmc.c
+++ b/drivers/platform/x86/amd/pmc.c
@@ -41,6 +41,7 @@
 #define AMD_PMC_STB_PMI_0		0x03E30600
 #define AMD_PMC_STB_S2IDLE_PREPARE	0xC6000001
 #define AMD_PMC_STB_S2IDLE_RESTORE	0xC6000002
+#define AMD_PMC_STB_S2IDLE_ENTER	0xC6000003
 
 /* STB S2D(Spill to DRAM) has different message port offset */
 #define STB_SPILL_TO_DRAM		0xBE
@@ -706,6 +707,17 @@ static void amd_pmc_s2idle_prepare(void)
 		dev_err(pdev->dev, "error writing to STB: %d\n", rc);
 }
 
+static void amd_pmc_s2idle_enter(void)
+{
+	struct amd_pmc_dev *pdev = &pmc;
+	int rc;
+
+	rc = amd_pmc_write_stb(pdev, AMD_PMC_STB_S2IDLE_ENTER);
+	if (rc)
+		dev_err(pdev->dev, "error writing to STB: %d\n", rc);
+
+}
+
 static void amd_pmc_s2idle_restore(void)
 {
 	struct amd_pmc_dev *pdev = &pmc;
@@ -733,6 +745,7 @@ static void amd_pmc_s2idle_restore(void)
 
 static struct acpi_s2idle_dev_ops amd_pmc_s2idle_dev_ops = {
 	.prepare = amd_pmc_s2idle_prepare,
+	.enter = amd_pmc_s2idle_enter,
 	.restore = amd_pmc_s2idle_restore,
 };
 #endif
-- 
2.34.1