mmc: sdhci-pci: Workaround GLK firmware failing to restore the tuning value

commit 5305ec6a upstream.

GLK firmware can indicate that the tuning value will be restored after
runtime suspend, but not actually do that. Add a workaround that detects
such cases, and lets the driver do re-tuning instead.
Reported-by: Anisse Astier <anisse@astier.eu>
Tested-by: Anisse Astier <anisse@astier.eu>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/mmc/host/sdhci-pci-core.c

@@ -12,6 +12,7 @@
  *     - JMicron (hardware and technical support)
  */
 
+#include <linux/bitfield.h>
 #include <linux/string.h>
 #include <linux/delay.h>
 #include <linux/highmem.h>
@@ -462,6 +463,9 @@ struct intel_host {
 	u32	dsm_fns;
 	int	drv_strength;
 	bool	d3_retune;
+	bool	rpm_retune_ok;
+	u32	glk_rx_ctrl1;
+	u32	glk_tun_val;
 };
 
 static const guid_t intel_dsm_guid =
@@ -791,6 +795,77 @@ static int glk_emmc_add_host(struct sdhci_pci_slot *slot)
 	return ret;
 }
 
+#ifdef CONFIG_PM
+#define GLK_RX_CTRL1	0x834
+#define GLK_TUN_VAL	0x840
+#define GLK_PATH_PLL	GENMASK(13, 8)
+#define GLK_DLY		GENMASK(6, 0)
+/* Workaround firmware failing to restore the tuning value */
+static void glk_rpm_retune_wa(struct sdhci_pci_chip *chip, bool susp)
+{
+	struct sdhci_pci_slot *slot = chip->slots[0];
+	struct intel_host *intel_host = sdhci_pci_priv(slot);
+	struct sdhci_host *host = slot->host;
+	u32 glk_rx_ctrl1;
+	u32 glk_tun_val;
+	u32 dly;
+
+	if (intel_host->rpm_retune_ok || !mmc_can_retune(host->mmc))
+		return;
+
+	glk_rx_ctrl1 = sdhci_readl(host, GLK_RX_CTRL1);
+	glk_tun_val = sdhci_readl(host, GLK_TUN_VAL);
+
+	if (susp) {
+		intel_host->glk_rx_ctrl1 = glk_rx_ctrl1;
+		intel_host->glk_tun_val = glk_tun_val;
+		return;
+	}
+
+	if (!intel_host->glk_tun_val)
+		return;
+
+	if (glk_rx_ctrl1 != intel_host->glk_rx_ctrl1) {
+		intel_host->rpm_retune_ok = true;
+		return;
+	}
+
+	dly = FIELD_PREP(GLK_DLY, FIELD_GET(GLK_PATH_PLL, glk_rx_ctrl1) +
+				  (intel_host->glk_tun_val << 1));
+	if (dly == FIELD_GET(GLK_DLY, glk_rx_ctrl1))
+		return;
+
+	glk_rx_ctrl1 = (glk_rx_ctrl1 & ~GLK_DLY) | dly;
+	sdhci_writel(host, glk_rx_ctrl1, GLK_RX_CTRL1);
+
+	intel_host->rpm_retune_ok = true;
+	chip->rpm_retune = true;
+	mmc_retune_needed(host->mmc);
+	pr_info("%s: Requiring re-tune after rpm resume", mmc_hostname(host->mmc));
+}
+
+static void glk_rpm_retune_chk(struct sdhci_pci_chip *chip, bool susp)
+{
+	if (chip->pdev->device == PCI_DEVICE_ID_INTEL_GLK_EMMC &&
+	    !chip->rpm_retune)
+		glk_rpm_retune_wa(chip, susp);
+}
+
+static int glk_runtime_suspend(struct sdhci_pci_chip *chip)
+{
+	glk_rpm_retune_chk(chip, true);
+
+	return sdhci_cqhci_runtime_suspend(chip);
+}
+
+static int glk_runtime_resume(struct sdhci_pci_chip *chip)
+{
+	glk_rpm_retune_chk(chip, false);
+
+	return sdhci_cqhci_runtime_resume(chip);
+}
+#endif
+
 #ifdef CONFIG_ACPI
 static int ni_set_max_freq(struct sdhci_pci_slot *slot)
 {
@@ -879,8 +954,8 @@ static const struct sdhci_pci_fixes sdhci_intel_glk_emmc = {
 	.resume			= sdhci_cqhci_resume,
 #endif
 #ifdef CONFIG_PM
-	.runtime_suspend	= sdhci_cqhci_runtime_suspend,
-	.runtime_resume		= sdhci_cqhci_runtime_resume,
+	.runtime_suspend	= glk_runtime_suspend,
+	.runtime_resume		= glk_runtime_resume,
 #endif
 	.quirks			= SDHCI_QUIRK_NO_ENDATTR_IN_NOPDESC,
 	.quirks2		= SDHCI_QUIRK2_PRESET_VALUE_BROKEN |