1 files changed, 115 insertions, 13 deletions

diff --git a/drivers/mmc/host/sdhci-acpi.c b/drivers/mmc/host/sdhci-acpi.c
index 48ecbd0b180d..54205e3be9e8 100644
--- a/drivers/mmc/host/sdhci-acpi.c
+++ b/drivers/mmc/host/sdhci-acpi.c
@@ -535,6 +535,11 @@ static const struct sdhci_acpi_slot sdhci_acpi_slot_qcom_sd = {
 	.caps    = MMC_CAP_NONREMOVABLE,
 };
 
+struct amd_sdhci_host {
+	bool	tuned_clock;
+	bool	dll_enabled;
+};
+
 /* AMD sdhci reset dll register. */
 #define SDHCI_AMD_RESET_DLL_REGISTER    0x908
 
@@ -546,39 +551,96 @@ static int amd_select_drive_strength(struct mmc_card *card,
 	return MMC_SET_DRIVER_TYPE_A;
 }
 
-static void sdhci_acpi_amd_hs400_dll(struct sdhci_host *host)
+static void sdhci_acpi_amd_hs400_dll(struct sdhci_host *host, bool enable)
 {
+	struct sdhci_acpi_host *acpi_host = sdhci_priv(host);
+	struct amd_sdhci_host *amd_host = sdhci_acpi_priv(acpi_host);
+
 	/* AMD Platform requires dll setting */
 	sdhci_writel(host, 0x40003210, SDHCI_AMD_RESET_DLL_REGISTER);
 	usleep_range(10, 20);
-	sdhci_writel(host, 0x40033210, SDHCI_AMD_RESET_DLL_REGISTER);
+	if (enable)
+		sdhci_writel(host, 0x40033210, SDHCI_AMD_RESET_DLL_REGISTER);
+
+	amd_host->dll_enabled = enable;
 }
 
 /*
- * For AMD Platform it is required to disable the tuning
- * bit first controller to bring to HS Mode from HS200
- * mode, later enable to tune to HS400 mode.
+ * The initialization sequence for HS400 is:
+ *     HS->HS200->Perform Tuning->HS->HS400
+ *
+ * The re-tuning sequence is:
+ *     HS400->DDR52->HS->HS200->Perform Tuning->HS->HS400
+ *
+ * The AMD eMMC Controller can only use the tuned clock while in HS200 and HS400
+ * mode. If we switch to a different mode, we need to disable the tuned clock.
+ * If we have previously performed tuning and switch back to HS200 or
+ * HS400, we can re-enable the tuned clock.
+ *
  */
 static void amd_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
 {
 	struct sdhci_host *host = mmc_priv(mmc);
+	struct sdhci_acpi_host *acpi_host = sdhci_priv(host);
+	struct amd_sdhci_host *amd_host = sdhci_acpi_priv(acpi_host);
 	unsigned int old_timing = host->timing;
+	u16 val;
 
 	sdhci_set_ios(mmc, ios);
-	if (old_timing == MMC_TIMING_MMC_HS200 &&
-	    ios->timing == MMC_TIMING_MMC_HS)
-		sdhci_writew(host, 0x9, SDHCI_HOST_CONTROL2);
-	if (old_timing != MMC_TIMING_MMC_HS400 &&
-	    ios->timing == MMC_TIMING_MMC_HS400) {
-		sdhci_writew(host, 0x80, SDHCI_HOST_CONTROL2);
-		sdhci_acpi_amd_hs400_dll(host);
+
+	if (old_timing != host->timing && amd_host->tuned_clock) {
+		if (host->timing == MMC_TIMING_MMC_HS400 ||
+		    host->timing == MMC_TIMING_MMC_HS200) {
+			val = sdhci_readw(host, SDHCI_HOST_CONTROL2);
+			val |= SDHCI_CTRL_TUNED_CLK;
+			sdhci_writew(host, val, SDHCI_HOST_CONTROL2);
+		} else {
+			val = sdhci_readw(host, SDHCI_HOST_CONTROL2);
+			val &= ~SDHCI_CTRL_TUNED_CLK;
+			sdhci_writew(host, val, SDHCI_HOST_CONTROL2);
+		}
+
+		/* DLL is only required for HS400 */
+		if (host->timing == MMC_TIMING_MMC_HS400 &&
+		    !amd_host->dll_enabled)
+			sdhci_acpi_amd_hs400_dll(host, true);
 	}
 }
 
+static int amd_sdhci_execute_tuning(struct mmc_host *mmc, u32 opcode)
+{
+	int err;
+	struct sdhci_host *host = mmc_priv(mmc);
+	struct sdhci_acpi_host *acpi_host = sdhci_priv(host);
+	struct amd_sdhci_host *amd_host = sdhci_acpi_priv(acpi_host);
+
+	amd_host->tuned_clock = false;
+
+	err = sdhci_execute_tuning(mmc, opcode);
+
+	if (!err && !host->tuning_err)
+		amd_host->tuned_clock = true;
+
+	return err;
+}
+
+static void amd_sdhci_reset(struct sdhci_host *host, u8 mask)
+{
+	struct sdhci_acpi_host *acpi_host = sdhci_priv(host);
+	struct amd_sdhci_host *amd_host = sdhci_acpi_priv(acpi_host);
+
+	if (mask & SDHCI_RESET_ALL) {
+		amd_host->tuned_clock = false;
+		sdhci_acpi_amd_hs400_dll(host, false);
+	}
+
+	sdhci_reset(host, mask);
+}
+
 static const struct sdhci_ops sdhci_acpi_ops_amd = {
 	.set_clock	= sdhci_set_clock,
 	.set_bus_width	= sdhci_set_bus_width,
-	.reset		= sdhci_reset,
+	.reset		= amd_sdhci_reset,
 	.set_uhs_signaling = sdhci_set_uhs_signaling,
 };
 
@@ -600,8 +662,46 @@ static int sdhci_acpi_emmc_amd_probe_slot(struct platform_device *pdev,
 	    (host->mmc->caps & MMC_CAP_1_8V_DDR))
 		host->mmc->caps2 = MMC_CAP2_HS400_1_8V;
 
+	/*
+	 * There are two types of presets out in the wild:
+	 * 1) Default/broken presets.
+	 *    These presets have two sets of problems:
+	 *    a) The clock divisor for SDR12, SDR25, and SDR50 is too small.
+	 *       This results in clock frequencies that are 2x higher than
+	 *       acceptable. i.e., SDR12 = 25 MHz, SDR25 = 50 MHz, SDR50 =
+	 *       100 MHz.x
+	 *    b) The HS200 and HS400 driver strengths don't match.
+	 *       By default, the SDR104 preset register has a driver strength of
+	 *       A, but the (internal) HS400 preset register has a driver
+	 *       strength of B. As part of initializing HS400, HS200 tuning
+	 *       needs to be performed. Having different driver strengths
+	 *       between tuning and operation is wrong. It results in different
+	 *       rise/fall times that lead to incorrect sampling.
+	 * 2) Firmware with properly initialized presets.
+	 *    These presets have proper clock divisors. i.e., SDR12 => 12MHz,
+	 *    SDR25 => 25 MHz, SDR50 => 50 MHz. Additionally the HS200 and
+	 *    HS400 preset driver strengths match.
+	 *
+	 *    Enabling presets for HS400 doesn't work for the following reasons:
+	 *    1) sdhci_set_ios has a hard coded list of timings that are used
+	 *       to determine if presets should be enabled.
+	 *    2) sdhci_get_preset_value is using a non-standard register to
+	 *       read out HS400 presets. The AMD controller doesn't support this
+	 *       non-standard register. In fact, it doesn't expose the HS400
+	 *       preset register anywhere in the SDHCI memory map. This results
+	 *       in reading a garbage value and using the wrong presets.
+	 *
+	 *       Since HS400 and HS200 presets must be identical, we could
+	 *       instead use the the SDR104 preset register.
+	 *
+	 *    If the above issues are resolved we could remove this quirk for
+	 *    firmware that that has valid presets (i.e., SDR12 <= 12 MHz).
+	 */
+	host->quirks2 |= SDHCI_QUIRK2_PRESET_VALUE_BROKEN;
+
 	host->mmc_host_ops.select_drive_strength = amd_select_drive_strength;
 	host->mmc_host_ops.set_ios = amd_set_ios;
+	host->mmc_host_ops.execute_tuning = amd_sdhci_execute_tuning;
 	return 0;
 }
 
@@ -613,6 +713,7 @@ static const struct sdhci_acpi_slot sdhci_acpi_slot_amd_emmc = {
 			  SDHCI_QUIRK_32BIT_ADMA_SIZE,
 	.quirks2	= SDHCI_QUIRK2_BROKEN_64_BIT_DMA,
 	.probe_slot     = sdhci_acpi_emmc_amd_probe_slot,
+	.priv_size	= sizeof(struct amd_sdhci_host),
 };
 
 struct sdhci_acpi_uid_slot {
@@ -963,6 +1064,7 @@ static const struct dev_pm_ops sdhci_acpi_pm_ops = {
 static struct platform_driver sdhci_acpi_driver = {
 	.driver = {
 		.name			= "sdhci-acpi",
+		.probe_type		= PROBE_PREFER_ASYNCHRONOUS,
 		.acpi_match_table	= sdhci_acpi_ids,
 		.pm			= &sdhci_acpi_pm_ops,
 	},