[RFC PATCH 1/1] mmc: sdhci-pci-gli: fix x86/S0ix SoCs suspend for GL9767

[Georg Gottleuber <g.gottleuber@tuxedocomputers.com>]

Adapt commit 1202d617e3d04c ("mmc: sdhci-pci-gli: fix LPM negotiation
so x86/S0ix SoCs can suspend") also for GL9767 card reader.

This patch was written without specs or deeper knowledge of PCI sleep
states. Tests show that S0ix is reached and a lower power consumption
when suspended (6 watts vs 1.2 watts for TUXEDO InfinityBook Pro Gen9
Intel).

The function of the card reader appears to be normal.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=219284
Co-developed-by: Christoffer Sandberg <cs@tuxedo.de>
Signed-off-by: Christoffer Sandberg <cs@tuxedo.de>
Signed-off-by: Georg Gottleuber <ggo@tuxedocomputers.com>
---
 drivers/mmc/host/sdhci-pci-gli.c | 65 +++++++++++++++++++++++++++++++-
 1 file changed, 64 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/host/sdhci-pci-gli.c
b/drivers/mmc/host/sdhci-pci-gli.c
index 0f81586a19df..40f43f5cd5c7 100644
--- a/drivers/mmc/host/sdhci-pci-gli.c
+++ b/drivers/mmc/host/sdhci-pci-gli.c
@@ -1205,6 +1205,32 @@ static void
gl9763e_set_low_power_negotiation(struct sdhci_pci_slot *slot,
        pci_write_config_dword(pdev, PCIE_GLI_9763E_VHS, value);
 }

+static void gl9767_set_low_power_negotiation(struct sdhci_pci_slot *slot,
+                                            bool enable)
+{
+       struct pci_dev *pdev = slot->chip->pdev;
+       u32 value;
+
+       pci_read_config_dword(pdev, PCIE_GLI_9767_VHS, &value);
+       value &= ~GLI_9767_VHS_REV;
+       value |= FIELD_PREP(GLI_9767_VHS_REV, GLI_9767_VHS_REV_W);
+       pci_write_config_dword(pdev, PCIE_GLI_9767_VHS, value);
+
+       pci_read_config_dword(pdev, PCIE_GLI_9767_CFG, &value);
+
+       if (enable)
+               value &= ~PCIE_GLI_9767_CFG_LOW_PWR_OFF;
+       else
+               value |= PCIE_GLI_9767_CFG_LOW_PWR_OFF;
+
+       pci_write_config_dword(pdev, PCIE_GLI_9767_CFG, value);
+
+       pci_read_config_dword(pdev, PCIE_GLI_9767_VHS, &value);
+       value &= ~GLI_9767_VHS_REV;
+       value |= FIELD_PREP(GLI_9767_VHS_REV, GLI_9767_VHS_REV_R);
+       pci_write_config_dword(pdev, PCIE_GLI_9767_VHS, value);
+}
+
 static void sdhci_set_gl9763e_signaling(struct sdhci_host *host,
                                        unsigned int timing)
 {
@@ -1470,6 +1496,42 @@ static int gl9763e_suspend(struct sdhci_pci_chip
*chip)
        gl9763e_set_low_power_negotiation(slot, false);
        return ret;
 }
+
+static int gl9767_resume(struct sdhci_pci_chip *chip)
+{
+       struct sdhci_pci_slot *slot = chip->slots[0];
+       int ret;
+
+       ret = sdhci_pci_gli_resume(chip);
+       if (ret)
+               return ret;
+
+       gl9767_set_low_power_negotiation(slot, false);
+
+       return 0;
+}
+
+static int gl9767_suspend(struct sdhci_pci_chip *chip)
+{
+       struct sdhci_pci_slot *slot = chip->slots[0];
+       int ret;
+
+       /*
+        * Certain SoCs can suspend only with the bus in low-
+        * power state, notably x86 SoCs when using S0ix.
+        * Re-enable LPM negotiation to allow entering L1 state
+        * and entering system suspend.
+        */
+       gl9767_set_low_power_negotiation(slot, true);
+
+       ret = sdhci_suspend_host(slot->host);
+       if (ret) {
+               gl9767_set_low_power_negotiation(slot, false);
+               return ret;
+       }
+
+       return 0;
+}
 #endif

 static int gli_probe_slot_gl9763e(struct sdhci_pci_slot *slot)
@@ -1605,6 +1667,7 @@ const struct sdhci_pci_fixes sdhci_gl9767 = {
        .probe_slot     = gli_probe_slot_gl9767,
        .ops            = &sdhci_gl9767_ops,
 #ifdef CONFIG_PM_SLEEP
-       .resume         = sdhci_pci_gli_resume,
+       .resume         = gl9767_resume,
+       .suspend        = gl9767_suspend,
 #endif
 };
-- 
2.34.1