[PATCH v3 0/2] mmc: sdhci-of-dwcmshc: Add HPE GSC eMMC support

[PATCH v3 0/2] mmc: sdhci-of-dwcmshc: Add HPE GSC eMMC support

[nick.hawkins]

From: Nick Hawkins <nick.hawkins@hpe.com>

The HPE GSC is an ARM64 (Cortex-A53) BMC SoC used on HPE ProLiant
servers.  Its eMMC controller is based on the DesignWare Cores MSHC IP
(snps,dwcmshc) but requires a small set of platform-specific quirks
that cannot be expressed through the existing generic dwcmshc code
paths.

This series adds support for the 'hpe,gsc-dwcmshc' compatible:

Patch 1 extends the snps,dwcmshc-sdhci.yaml binding to document the
new compatible and the mandatory 'hpe,gxp-sysreg' syscon phandle for
MSHCCS register access.  The HPE GSC exposes only a single 'core'
clock, so the clocks/clock-names properties are constrained to a
single item for this compatible.

Patch 2 adds the HPE-specific driver code in sdhci-of-dwcmshc.c:

  * dwcmshc_hpe_set_clock(): SDHCI_CLOCK_CONTROL.freq_sel is wired to
    a clock mux on the GSC SoC, not a divider.  When running at
    200 MHz (HS200) freq_sel must be forced to 1 to select the correct
    high-frequency source.

  * dwcmshc_hpe_vendor_specific(): disables the command-conflict check
    and programs ATCTRL using existing AT_CTRL_* macros for reliable
    HS200 signal integrity on the GSC board topology.

  * dwcmshc_hpe_reset(): calls sdhci_reset(), re-applies vendor config,
    and unconditionally re-sets CARD_IS_EMMC.  The controller clears this
    bit on every reset; leaving it clear causes card-detect
    misidentification on the eMMC-only slot.

  * dwcmshc_hpe_set_uhs_signaling(): wraps dwcmshc_set_uhs_signaling()
    and unconditionally sets CARD_IS_EMMC for all timing modes.

  * dwcmshc_hpe_gsc_init(): obtains the SoC register block via the
    'hpe,gxp-sysreg' syscon phandle and sets SCGSyncDis (BIT(18)) in
    MSHCCS (offset 0x110) to allow the HS200 RX delay lines to settle
    while the card clock is stopped.  Enables SDHCI v4 mode.

  * sdhci_dwcmshc_hpe_gsc_pdata sets SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN
    (base clock not in capabilities) and SDHCI_QUIRK2_PRESET_VALUE_BROKEN
    (preset-value registers not populated in GSC ROM).

All new symbols are exclusively selected by the 'hpe,gsc-dwcmshc' OF
match entry.  No existing platform (Rockchip, T-Head, sg2042, Sophgo,
etc.) has any code path change.

Note: the DTS node for 'hpe,gsc-dwcmshc' will be submitted separately
as part of the HPE GSC base platform series (arch/arm64/boot/dts/hpe/).

Changes since v2:
  - Replaced raw ATCTRL magic value 0x021f0005 with existing AT_CTRL_*
    macros and FIELD_PREP(), as suggested by Shawn Lin.
  - Refactored dwcmshc_hpe_set_uhs_signaling() to wrap
    dwcmshc_set_uhs_signaling() instead of duplicating the body,
    as suggested by Shawn Lin.
  - Dropped redundant 'maxItems: 1' from clocks and clock-names in the
    dt-binding conditional block; the items list already implies the
    count (reported by dt-review-ci / dtschema).

Changes since v1:
  - Replaced the second reg entry for MSHCCS with an 'hpe,gxp-sysreg'
    syscon phandle + regmap access, as suggested by Conor Dooley.
  - Driver now uses syscon_regmap_lookup_by_phandle() and
    regmap_update_bits() instead of devm_platform_ioremap_resource().

Nick Hawkins (2):
  dt-bindings: mmc: snps,dwcmshc-sdhci: add HPE GSC dwcmshc compatible
  mmc: sdhci-of-dwcmshc: Add HPE GSC eMMC support

 .../bindings/mmc/snps,dwcmshc-sdhci.yaml      |  36 +++++
 drivers/mmc/host/sdhci-of-dwcmshc.c           | 149 ++++++++++++++++++
 2 files changed, 185 insertions(+)

-- 
2.34.1

[PATCH v3 1/2] dt-bindings: mmc: snps,dwcmshc-sdhci: add HPE GSC dwcmshc compatible

[nick.hawkins]

From: Nick Hawkins <nick.hawkins@hpe.com>

Add the 'hpe,gsc-dwcmshc' compatible string for the HPE GSC (ARM64
Cortex-A53) BMC SoC eMMC controller.

The HPE GSC requires access to the MSHCCS register in the SoC system
register block to configure SCG sync disable (bit 18) for HS200 RX
delay-line phase selection.  The existing 'hpe,gxp-sysreg' syscon
phandle is required for this compatible to access MSHCCS via regmap.

The HPE GSC eMMC interface only exposes a single 'core' clock (no
bus clock), so clocks/clock-names are constrained to a single item.

Add an example node with the hpe,gxp-sysreg syscon reference.

Signed-off-by: Nick Hawkins <nick.hawkins@hpe.com>
---
 .../bindings/mmc/snps,dwcmshc-sdhci.yaml      | 36 +++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/Documentation/devicetree/bindings/mmc/snps,dwcmshc-sdhci.yaml b/Documentation/devicetree/bindings/mmc/snps,dwcmshc-sdhci.yaml
index 7e7c55dc2440..74734d46c70d 100644
--- a/Documentation/devicetree/bindings/mmc/snps,dwcmshc-sdhci.yaml
+++ b/Documentation/devicetree/bindings/mmc/snps,dwcmshc-sdhci.yaml
@@ -23,6 +23,7 @@ properties:
           - const: sophgo,sg2044-dwcmshc
           - const: sophgo,sg2042-dwcmshc
       - enum:
+          - hpe,gsc-dwcmshc
           - rockchip,rk3568-dwcmshc
           - rockchip,rk3588-dwcmshc
           - snps,dwcmshc-sdhci
@@ -77,6 +78,13 @@ properties:
     description: Specifies the drive impedance in Ohm.
     enum: [33, 40, 50, 66, 100]
 
+  hpe,gxp-sysreg:
+    $ref: /schemas/types.yaml#/definitions/phandle
+    description:
+      Phandle to the HPE GXP SoC system register block (syscon).
+      The driver accesses the MSHCCS register at offset 0x110 within
+      this block to configure clock synchronisation for HS200 tuning.
+
 required:
   - compatible
   - reg
@@ -87,6 +95,23 @@ required:
 allOf:
   - $ref: mmc-controller.yaml#
 
+  - if:
+      properties:
+        compatible:
+          contains:
+            const: hpe,gsc-dwcmshc
+
+    then:
+      properties:
+        clocks:
+          items:
+            - description: core clock
+        clock-names:
+          items:
+            - const: core
+      required:
+        - hpe,gxp-sysreg
+
   - if:
       properties:
         compatible:
@@ -190,5 +215,16 @@ examples:
       #address-cells = <1>;
       #size-cells = <0>;
     };
+  - |
+    mmc@c0100000 {
+      compatible = "hpe,gsc-dwcmshc";
+      reg = <0xc0100000 0x1000>;
+      interrupts = <0 17 0x4>;
+      clocks = <&emmcclk>;
+      clock-names = "core";
+      hpe,gxp-sysreg = <&soc_ctrl>;
+      bus-width = <8>;
+      non-removable;
+    };
 
 ...
-- 
2.34.1

Re: [PATCH v3 1/2] dt-bindings: mmc: snps,dwcmshc-sdhci: add HPE GSC dwcmshc compatible

[Krzysztof Kozlowski]

On Wed, Mar 11, 2026 at 01:11:11PM -0500, nick.hawkins@hpe.com wrote:
> From: Nick Hawkins <nick.hawkins@hpe.com>
> 
> Add the 'hpe,gsc-dwcmshc' compatible string for the HPE GSC (ARM64
> Cortex-A53) BMC SoC eMMC controller.
> 
> The HPE GSC requires access to the MSHCCS register in the SoC system
> register block to configure SCG sync disable (bit 18) for HS200 RX
> delay-line phase selection.  The existing 'hpe,gxp-sysreg' syscon
> phandle is required for this compatible to access MSHCCS via regmap.
> 
> The HPE GSC eMMC interface only exposes a single 'core' clock (no
> bus clock), so clocks/clock-names are constrained to a single item.
> 
> Add an example node with the hpe,gxp-sysreg syscon reference.

Difference in one property does not warrant new example as there are
already two examples (two are enough usually). Drop.

> 
> Signed-off-by: Nick Hawkins <nick.hawkins@hpe.com>
> ---
>  .../bindings/mmc/snps,dwcmshc-sdhci.yaml      | 36 +++++++++++++++++++
>  1 file changed, 36 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/mmc/snps,dwcmshc-sdhci.yaml b/Documentation/devicetree/bindings/mmc/snps,dwcmshc-sdhci.yaml
> index 7e7c55dc2440..74734d46c70d 100644
> --- a/Documentation/devicetree/bindings/mmc/snps,dwcmshc-sdhci.yaml
> +++ b/Documentation/devicetree/bindings/mmc/snps,dwcmshc-sdhci.yaml
> @@ -23,6 +23,7 @@ properties:
>            - const: sophgo,sg2044-dwcmshc
>            - const: sophgo,sg2042-dwcmshc
>        - enum:
> +          - hpe,gsc-dwcmshc
>            - rockchip,rk3568-dwcmshc
>            - rockchip,rk3588-dwcmshc
>            - snps,dwcmshc-sdhci
> @@ -77,6 +78,13 @@ properties:
>      description: Specifies the drive impedance in Ohm.
>      enum: [33, 40, 50, 66, 100]
>  
> +  hpe,gxp-sysreg:
> +    $ref: /schemas/types.yaml#/definitions/phandle
> +    description:
> +      Phandle to the HPE GXP SoC system register block (syscon).
> +      The driver accesses the MSHCCS register at offset 0x110 within
> +      this block to configure clock synchronisation for HS200 tuning.

You need only one reg, from that syscon, so you should pass it as
argument:
https://elixir.bootlin.com/linux/v5.18-rc1/source/Documentation/devicetree/bindings/soc/samsung/exynos-usi.yaml#L42

> +
>  required:
>    - compatible
>    - reg
> @@ -87,6 +95,23 @@ required:
>  allOf:
>    - $ref: mmc-controller.yaml#
>  
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            const: hpe,gsc-dwcmshc
> +
> +    then:
> +      properties:
> +        clocks:
> +          items:
> +            - description: core clock
> +        clock-names:
> +          items:
> +            - const: core
> +      required:
> +        - hpe,gxp-sysreg

else:
  properties:
    hpe,gxp-sysreg: false

    Best regards,
    Krzysztof

[PATCH v3 2/2] mmc: sdhci-of-dwcmshc: Add HPE GSC eMMC support

[nick.hawkins]

From: Nick Hawkins <nick.hawkins@hpe.com>

Add support for the eMMC controller integrated in the HPE GSC (ARM64
Cortex-A53) BMC SoC under the new 'hpe,gsc-dwcmshc' compatible
string.

The HPE GSC eMMC controller is based on the DesignWare Cores MSHC IP
but requires several platform-specific adjustments:

Clock mux (dwcmshc_hpe_set_clock):
  The GSC SoC wires SDHCI_CLOCK_CONTROL.freq_sel directly to a clock
  mux rather than a divider.  Forcing freq_sel = 1 when the requested
  clock is 200 MHz (HS200) selects the correct high-speed clock source.
  Using the generic sdhci_set_clock() would otherwise leave the mux on
  the wrong source after tuning.

Auto-tuning / vendor config (dwcmshc_hpe_vendor_specific):
  Disables the command-conflict check (DWCMSHC_HOST_CTRL3 BIT(0)) and
  programs the ATCTRL register using existing AT_CTRL_* macros:
    AT_CTRL_AT_EN           auto-tuning circuit enable
    AT_CTRL_SWIN_TH_EN      sampling window threshold enable
    AT_CTRL_TUNE_CLK_STOP_EN tune-clock-stop enable
    PRE_CHANGE_DLY  = 3     pre-change delay
    POST_CHANGE_DLY = 3     post-change delay
    SWIN_TH_VAL    = 2      sampling window threshold
  This combination is required for reliable HS200 signal integrity on
  the GSC PCB trace topology.

Reset (dwcmshc_hpe_reset):
  Calls sdhci_reset(), re-applies the vendor config above, and then
  sets DWCMSHC_CARD_IS_EMMC unconditionally.  The GSC controller
  clears this bit on every reset; leaving it clear causes card-detect
  mis-identification on an eMMC-only slot.

UHS signaling (dwcmshc_hpe_set_uhs_signaling):
  Wraps dwcmshc_set_uhs_signaling() and unconditionally sets
  CARD_IS_EMMC for all timing modes, not just HS400.

Init (dwcmshc_hpe_gsc_init):
  Obtains the SoC register block via the 'hpe,gxp-sysreg' syscon
  phandle and sets SCGSyncDis (BIT(18)) in MSHCCS (offset 0x110)
  to allow the HS200 RX delay lines to settle while the card clock
  is stopped during auto-tuning.  Enables SDHCI v4 mode.

Quirks:
  SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN:  base clock not advertised in
    capabilities; must be obtained from the DTS 'clocks' property.
  SDHCI_QUIRK2_PRESET_VALUE_BROKEN:  preset-value registers are not
    populated in the GSC ROM.

All HPE-specific code is isolated to the new hpe_gsc_init / hpe_ops /
hpe_gsc_pdata symbols.  No existing platform (Rockchip, T-Head, sg2042,
etc.) is affected.

Signed-off-by: Nick Hawkins <nick.hawkins@hpe.com>
---
 drivers/mmc/host/sdhci-of-dwcmshc.c | 149 ++++++++++++++++++++++++++++
 1 file changed, 149 insertions(+)

diff --git a/drivers/mmc/host/sdhci-of-dwcmshc.c b/drivers/mmc/host/sdhci-of-dwcmshc.c
index 2b75a36c096b..46662071cc61 100644
--- a/drivers/mmc/host/sdhci-of-dwcmshc.c
+++ b/drivers/mmc/host/sdhci-of-dwcmshc.c
@@ -1245,6 +1245,132 @@ static int sg2042_init(struct device *dev, struct sdhci_host *host,
 					     ARRAY_SIZE(clk_ids), clk_ids);
 }
 
+/* HPE GSC-specific vendor configuration: disable command conflict check
+ * and program Auto-Tuning Control register.
+ */
+static void dwcmshc_hpe_vendor_specific(struct sdhci_host *host)
+{
+	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+	struct dwcmshc_priv *dwc_priv = sdhci_pltfm_priv(pltfm_host);
+	u32 atctrl;
+	u8 extra;
+
+	extra = sdhci_readb(host, dwc_priv->vendor_specific_area1 + DWCMSHC_HOST_CTRL3);
+	extra &= ~BIT(0);
+	sdhci_writeb(host, extra, dwc_priv->vendor_specific_area1 + DWCMSHC_HOST_CTRL3);
+
+	atctrl = AT_CTRL_AT_EN | AT_CTRL_SWIN_TH_EN | AT_CTRL_TUNE_CLK_STOP_EN |
+		FIELD_PREP(AT_CTRL_PRE_CHANGE_DLY_MASK, 3) |
+		FIELD_PREP(AT_CTRL_POST_CHANGE_DLY_MASK, AT_CTRL_POST_CHANGE_DLY) |
+		FIELD_PREP(AT_CTRL_SWIN_TH_VAL_MASK, 2);
+	sdhci_writel(host, atctrl, dwc_priv->vendor_specific_area1 + DWCMSHC_EMMC_ATCTRL);
+}
+
+static void dwcmshc_hpe_reset(struct sdhci_host *host, u8 mask)
+{
+	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+	struct dwcmshc_priv *dwc_priv = sdhci_pltfm_priv(pltfm_host);
+	u16 ctrl;
+
+	dwcmshc_reset(host, mask);
+
+	dwcmshc_hpe_vendor_specific(host);
+
+	/* HPE GSC eMMC always needs CARD_IS_EMMC set after reset */
+	ctrl = sdhci_readw(host, dwc_priv->vendor_specific_area1 + DWCMSHC_EMMC_CONTROL);
+	ctrl |= DWCMSHC_CARD_IS_EMMC;
+	sdhci_writew(host, ctrl, dwc_priv->vendor_specific_area1 + DWCMSHC_EMMC_CONTROL);
+}
+
+static void dwcmshc_hpe_set_uhs_signaling(struct sdhci_host *host,
+					  unsigned int timing)
+{
+	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+	struct dwcmshc_priv *priv = sdhci_pltfm_priv(pltfm_host);
+	u16 ctrl;
+
+	dwcmshc_set_uhs_signaling(host, timing);
+
+	/* HPE GSC: always set CARD_IS_EMMC for all timing modes */
+	ctrl = sdhci_readw(host, priv->vendor_specific_area1 + DWCMSHC_EMMC_CONTROL);
+	ctrl |= DWCMSHC_CARD_IS_EMMC;
+	sdhci_writew(host, ctrl, priv->vendor_specific_area1 + DWCMSHC_EMMC_CONTROL);
+}
+
+/*
+ * HPE GSC eMMC controller clock setup.
+ *
+ * The GSC SoC wires the freq_sel field of SDHCI_CLOCK_CONTROL directly to a
+ * clock mux rather than a divider. Force freq_sel = 1 when running at
+ * 200 MHz (HS200) so the mux selects the correct clock source.
+ */
+static void dwcmshc_hpe_set_clock(struct sdhci_host *host, unsigned int clock)
+{
+	u16 clk;
+
+	host->mmc->actual_clock = 0;
+
+	sdhci_writew(host, 0, SDHCI_CLOCK_CONTROL);
+
+	if (clock == 0)
+		return;
+
+	clk = sdhci_calc_clk(host, clock, &host->mmc->actual_clock);
+
+	if (host->mmc->actual_clock == 200000000)
+		clk |= (1 << SDHCI_DIVIDER_SHIFT);
+
+	sdhci_enable_clk(host, clk);
+}
+
+/*
+ * HPE GSC eMMC controller init.
+ *
+ * The GSC SoC requires configuring MSHCCS.  Bit 18 (SCGSyncDis) disables clock
+ * synchronisation for phase-select values going to the HS200 RX delay lines,
+ * allowing the card clock to be stopped while the delay selection settles and
+ * the phase shift is applied.  This must be used together with the ATCTRL
+ * settings programmed in dwcmshc_hpe_vendor_specific():
+ *   AT_CTRL_R.TUNE_CLK_STOP_EN  = 0x1
+ *   AT_CTRL_R.POST_CHANGE_DLY   = 0x3
+ *   AT_CTRL_R.PRE_CHANGE_DLY    = 0x3
+ *
+ * The DTS node provides a syscon phandle ('hpe,gxp-sysreg') to access
+ * this register at offset 0x110 within the SoC control block.
+ */
+#define HPE_GSC_MSHCCS_OFFSET		0x110
+#define HPE_GSC_MSHCCS_SCGSYNCDIS	BIT(18)
+
+static int dwcmshc_hpe_gsc_init(struct device *dev, struct sdhci_host *host,
+				struct dwcmshc_priv *dwc_priv)
+{
+	struct regmap *soc_ctrl;
+	int ret;
+
+	/* Disable cmd conflict check and configure auto-tuning */
+	dwcmshc_hpe_vendor_specific(host);
+
+	/* Look up the GXP sysreg syscon for MSHCCS access */
+	soc_ctrl = syscon_regmap_lookup_by_phandle(dev->of_node, "hpe,gxp-sysreg");
+	if (IS_ERR(soc_ctrl)) {
+		dev_err(dev, "failed to get hpe,gxp-sysreg syscon\n");
+		return PTR_ERR(soc_ctrl);
+	}
+
+	/* Set SCGSyncDis (bit 18) to disable sync on HS200 RX delay lines */
+	ret = regmap_update_bits(soc_ctrl, HPE_GSC_MSHCCS_OFFSET,
+				HPE_GSC_MSHCCS_SCGSYNCDIS,
+				HPE_GSC_MSHCCS_SCGSYNCDIS);
+	if (ret) {
+		dev_err(dev, "failed to set SCGSyncDis in MSHCCS\n");
+		return ret;
+	}
+
+	sdhci_enable_v4_mode(host);
+
+	return 0;
+}
+
 static void sdhci_eic7700_set_clock(struct sdhci_host *host, unsigned int clock)
 {
 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
@@ -1834,6 +1960,25 @@ static const struct dwcmshc_pltfm_data sdhci_dwcmshc_eic7700_pdata = {
 	.init = eic7700_init,
 };
 
+static const struct sdhci_ops sdhci_dwcmshc_hpe_ops = {
+	.set_clock		= dwcmshc_hpe_set_clock,
+	.set_bus_width		= sdhci_set_bus_width,
+	.set_uhs_signaling	= dwcmshc_hpe_set_uhs_signaling,
+	.get_max_clock		= dwcmshc_get_max_clock,
+	.reset			= dwcmshc_hpe_reset,
+	.adma_write_desc	= dwcmshc_adma_write_desc,
+	.irq			= dwcmshc_cqe_irq_handler,
+};
+
+static const struct dwcmshc_pltfm_data sdhci_dwcmshc_hpe_gsc_pdata = {
+	.pdata = {
+		.ops = &sdhci_dwcmshc_hpe_ops,
+		.quirks = SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN,
+		.quirks2 = SDHCI_QUIRK2_PRESET_VALUE_BROKEN,
+	},
+	.init = dwcmshc_hpe_gsc_init,
+};
+
 static const struct cqhci_host_ops dwcmshc_cqhci_ops = {
 	.enable		= dwcmshc_sdhci_cqe_enable,
 	.disable	= sdhci_cqe_disable,
@@ -1942,6 +2087,10 @@ static const struct of_device_id sdhci_dwcmshc_dt_ids[] = {
 		.compatible = "eswin,eic7700-dwcmshc",
 		.data = &sdhci_dwcmshc_eic7700_pdata,
 	},
+	{
+		.compatible = "hpe,gsc-dwcmshc",
+		.data = &sdhci_dwcmshc_hpe_gsc_pdata,
+	},
 	{},
 };
 MODULE_DEVICE_TABLE(of, sdhci_dwcmshc_dt_ids);
-- 
2.34.1

Re: [PATCH v3 2/2] mmc: sdhci-of-dwcmshc: Add HPE GSC eMMC support

[Shawn Lin]

在 2026/03/12 星期四 2:11, nick.hawkins@hpe.com 写道:
> From: Nick Hawkins <nick.hawkins@hpe.com>
> 
> Add support for the eMMC controller integrated in the HPE GSC (ARM64
> Cortex-A53) BMC SoC under the new 'hpe,gsc-dwcmshc' compatible
> string.
> 
> The HPE GSC eMMC controller is based on the DesignWare Cores MSHC IP
> but requires several platform-specific adjustments:
> 
> Clock mux (dwcmshc_hpe_set_clock):
>    The GSC SoC wires SDHCI_CLOCK_CONTROL.freq_sel directly to a clock
>    mux rather than a divider.  Forcing freq_sel = 1 when the requested
>    clock is 200 MHz (HS200) selects the correct high-speed clock source.
>    Using the generic sdhci_set_clock() would otherwise leave the mux on
>    the wrong source after tuning.
> 
> Auto-tuning / vendor config (dwcmshc_hpe_vendor_specific):
>    Disables the command-conflict check (DWCMSHC_HOST_CTRL3 BIT(0)) and
>    programs the ATCTRL register using existing AT_CTRL_* macros:
>      AT_CTRL_AT_EN           auto-tuning circuit enable
>      AT_CTRL_SWIN_TH_EN      sampling window threshold enable
>      AT_CTRL_TUNE_CLK_STOP_EN tune-clock-stop enable
>      PRE_CHANGE_DLY  = 3     pre-change delay
>      POST_CHANGE_DLY = 3     post-change delay
>      SWIN_TH_VAL    = 2      sampling window threshold
>    This combination is required for reliable HS200 signal integrity on
>    the GSC PCB trace topology.
> 
> Reset (dwcmshc_hpe_reset):
>    Calls sdhci_reset(), re-applies the vendor config above, and then
>    sets DWCMSHC_CARD_IS_EMMC unconditionally.  The GSC controller
>    clears this bit on every reset; leaving it clear causes card-detect
>    mis-identification on an eMMC-only slot.
> 
> UHS signaling (dwcmshc_hpe_set_uhs_signaling):
>    Wraps dwcmshc_set_uhs_signaling() and unconditionally sets
>    CARD_IS_EMMC for all timing modes, not just HS400.
> 
> Init (dwcmshc_hpe_gsc_init):
>    Obtains the SoC register block via the 'hpe,gxp-sysreg' syscon
>    phandle and sets SCGSyncDis (BIT(18)) in MSHCCS (offset 0x110)
>    to allow the HS200 RX delay lines to settle while the card clock
>    is stopped during auto-tuning.  Enables SDHCI v4 mode.
> 
> Quirks:
>    SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN:  base clock not advertised in
>      capabilities; must be obtained from the DTS 'clocks' property.
>    SDHCI_QUIRK2_PRESET_VALUE_BROKEN:  preset-value registers are not
>      populated in the GSC ROM.
> 
> All HPE-specific code is isolated to the new hpe_gsc_init / hpe_ops /
> hpe_gsc_pdata symbols.  No existing platform (Rockchip, T-Head, sg2042,
> etc.) is affected.
> 
> Signed-off-by: Nick Hawkins <nick.hawkins@hpe.com>
> ---
>   drivers/mmc/host/sdhci-of-dwcmshc.c | 149 ++++++++++++++++++++++++++++
>   1 file changed, 149 insertions(+)
> 
> diff --git a/drivers/mmc/host/sdhci-of-dwcmshc.c b/drivers/mmc/host/sdhci-of-dwcmshc.c
> index 2b75a36c096b..46662071cc61 100644
> --- a/drivers/mmc/host/sdhci-of-dwcmshc.c
> +++ b/drivers/mmc/host/sdhci-of-dwcmshc.c
> @@ -1245,6 +1245,132 @@ static int sg2042_init(struct device *dev, struct sdhci_host *host,
>   					     ARRAY_SIZE(clk_ids), clk_ids);
>   }
>   
> +/* HPE GSC-specific vendor configuration: disable command conflict check
> + * and program Auto-Tuning Control register.
> + */
> +static void dwcmshc_hpe_vendor_specific(struct sdhci_host *host)
> +{
> +	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> +	struct dwcmshc_priv *dwc_priv = sdhci_pltfm_priv(pltfm_host);
> +	u32 atctrl;
> +	u8 extra;
> +
> +	extra = sdhci_readb(host, dwc_priv->vendor_specific_area1 + DWCMSHC_HOST_CTRL3);
> +	extra &= ~BIT(0);
> +	sdhci_writeb(host, extra, dwc_priv->vendor_specific_area1 + DWCMSHC_HOST_CTRL3);
> +
> +	atctrl = AT_CTRL_AT_EN | AT_CTRL_SWIN_TH_EN | AT_CTRL_TUNE_CLK_STOP_EN |
> +		FIELD_PREP(AT_CTRL_PRE_CHANGE_DLY_MASK, 3) |
> +		FIELD_PREP(AT_CTRL_POST_CHANGE_DLY_MASK, AT_CTRL_POST_CHANGE_DLY) |
> +		FIELD_PREP(AT_CTRL_SWIN_TH_VAL_MASK, 2);
> +	sdhci_writel(host, atctrl, dwc_priv->vendor_specific_area1 + DWCMSHC_EMMC_ATCTRL);
> +}
> +
> +static void dwcmshc_hpe_reset(struct sdhci_host *host, u8 mask)
> +{
> +	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> +	struct dwcmshc_priv *dwc_priv = sdhci_pltfm_priv(pltfm_host);
> +	u16 ctrl;
> +
> +	dwcmshc_reset(host, mask);
> +
> +	dwcmshc_hpe_vendor_specific(host);
> +
> +	/* HPE GSC eMMC always needs CARD_IS_EMMC set after reset */
> +	ctrl = sdhci_readw(host, dwc_priv->vendor_specific_area1 + DWCMSHC_EMMC_CONTROL);
> +	ctrl |= DWCMSHC_CARD_IS_EMMC;
> +	sdhci_writew(host, ctrl, dwc_priv->vendor_specific_area1 + DWCMSHC_EMMC_CONTROL);
> +}
> +
> +static void dwcmshc_hpe_set_uhs_signaling(struct sdhci_host *host,
> +					  unsigned int timing)
> +{
> +	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> +	struct dwcmshc_priv *priv = sdhci_pltfm_priv(pltfm_host);
> +	u16 ctrl;
> +
> +	dwcmshc_set_uhs_signaling(host, timing);
> +
> +	/* HPE GSC: always set CARD_IS_EMMC for all timing modes */
> +	ctrl = sdhci_readw(host, priv->vendor_specific_area1 + DWCMSHC_EMMC_CONTROL);
> +	ctrl |= DWCMSHC_CARD_IS_EMMC;
> +	sdhci_writew(host, ctrl, priv->vendor_specific_area1 + DWCMSHC_EMMC_CONTROL);
> +}
> +
> +/*
> + * HPE GSC eMMC controller clock setup.
> + *
> + * The GSC SoC wires the freq_sel field of SDHCI_CLOCK_CONTROL directly to a
> + * clock mux rather than a divider. Force freq_sel = 1 when running at
> + * 200 MHz (HS200) so the mux selects the correct clock source.
> + */
> +static void dwcmshc_hpe_set_clock(struct sdhci_host *host, unsigned int clock)
> +{
> +	u16 clk;
> +
> +	host->mmc->actual_clock = 0;
> +
> +	sdhci_writew(host, 0, SDHCI_CLOCK_CONTROL);
> +
> +	if (clock == 0)
> +		return;
> +
> +	clk = sdhci_calc_clk(host, clock, &host->mmc->actual_clock);
> +
> +	if (host->mmc->actual_clock == 200000000)
> +		clk |= (1 << SDHCI_DIVIDER_SHIFT);
> +
> +	sdhci_enable_clk(host, clk);
> +}
> +
> +/*
> + * HPE GSC eMMC controller init.
> + *
> + * The GSC SoC requires configuring MSHCCS.  Bit 18 (SCGSyncDis) disables clock
> + * synchronisation for phase-select values going to the HS200 RX delay lines,
> + * allowing the card clock to be stopped while the delay selection settles and
> + * the phase shift is applied.  This must be used together with the ATCTRL
> + * settings programmed in dwcmshc_hpe_vendor_specific():
> + *   AT_CTRL_R.TUNE_CLK_STOP_EN  = 0x1
> + *   AT_CTRL_R.POST_CHANGE_DLY   = 0x3
> + *   AT_CTRL_R.PRE_CHANGE_DLY    = 0x3
> + *
> + * The DTS node provides a syscon phandle ('hpe,gxp-sysreg') to access
> + * this register at offset 0x110 within the SoC control block.
> + */
> +#define HPE_GSC_MSHCCS_OFFSET		0x110
> +#define HPE_GSC_MSHCCS_SCGSYNCDIS	BIT(18)
> +

I guess you should move these macros to the beginning of this c file.

> +static int dwcmshc_hpe_gsc_init(struct device *dev, struct sdhci_host *host,
> +				struct dwcmshc_priv *dwc_priv)
> +{
> +	struct regmap *soc_ctrl;
> +	int ret;
> +
> +	/* Disable cmd conflict check and configure auto-tuning */
> +	dwcmshc_hpe_vendor_specific(host);
> +
> +	/* Look up the GXP sysreg syscon for MSHCCS access */
> +	soc_ctrl = syscon_regmap_lookup_by_phandle(dev->of_node, "hpe,gxp-sysreg");
> +	if (IS_ERR(soc_ctrl)) {
> +		dev_err(dev, "failed to get hpe,gxp-sysreg syscon\n");
> +		return PTR_ERR(soc_ctrl);
> +	}
> +
> +	/* Set SCGSyncDis (bit 18) to disable sync on HS200 RX delay lines */
> +	ret = regmap_update_bits(soc_ctrl, HPE_GSC_MSHCCS_OFFSET,
> +				HPE_GSC_MSHCCS_SCGSYNCDIS,
> +				HPE_GSC_MSHCCS_SCGSYNCDIS);
> +	if (ret) {
> +		dev_err(dev, "failed to set SCGSyncDis in MSHCCS\n");
> +		return ret;
> +	}
> +
> +	sdhci_enable_v4_mode(host);

Sorry, I overlooked this part when in v2. But we enable it in
dwcmshc_probe() based on the capabilities, isn't it? Unless your
hardware didn't set SDHCI_CAN_64BIT_V4 but actually it does support
it? Then it perhaps should be a quirk, although we in general would like
to avoid more quirks... It depends on Adrian.

Btw, unlated to your patch, but th1520 did it the same way... Hmm

> +
> +	return 0;
> +}
> +
>   static void sdhci_eic7700_set_clock(struct sdhci_host *host, unsigned int clock)
>   {
>   	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> @@ -1834,6 +1960,25 @@ static const struct dwcmshc_pltfm_data sdhci_dwcmshc_eic7700_pdata = {
>   	.init = eic7700_init,
>   };
>   
> +static const struct sdhci_ops sdhci_dwcmshc_hpe_ops = {
> +	.set_clock		= dwcmshc_hpe_set_clock,
> +	.set_bus_width		= sdhci_set_bus_width,
> +	.set_uhs_signaling	= dwcmshc_hpe_set_uhs_signaling,
> +	.get_max_clock		= dwcmshc_get_max_clock,
> +	.reset			= dwcmshc_hpe_reset,
> +	.adma_write_desc	= dwcmshc_adma_write_desc,
> +	.irq			= dwcmshc_cqe_irq_handler,
> +};
> +
> +static const struct dwcmshc_pltfm_data sdhci_dwcmshc_hpe_gsc_pdata = {
> +	.pdata = {
> +		.ops = &sdhci_dwcmshc_hpe_ops,
> +		.quirks = SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN,
> +		.quirks2 = SDHCI_QUIRK2_PRESET_VALUE_BROKEN,
> +	},
> +	.init = dwcmshc_hpe_gsc_init,
> +};
> +
>   static const struct cqhci_host_ops dwcmshc_cqhci_ops = {
>   	.enable		= dwcmshc_sdhci_cqe_enable,
>   	.disable	= sdhci_cqe_disable,
> @@ -1942,6 +2087,10 @@ static const struct of_device_id sdhci_dwcmshc_dt_ids[] = {
>   		.compatible = "eswin,eic7700-dwcmshc",
>   		.data = &sdhci_dwcmshc_eic7700_pdata,
>   	},
> +	{
> +		.compatible = "hpe,gsc-dwcmshc",
> +		.data = &sdhci_dwcmshc_hpe_gsc_pdata,
> +	},
>   	{},
>   };
>   MODULE_DEVICE_TABLE(of, sdhci_dwcmshc_dt_ids);
> 

RE: [PATCH v3 2/2] mmc: sdhci-of-dwcmshc: Add HPE GSC eMMC support

[Hawkins, Nick]

Hi Shawn, thank you for your input.

See below:

> -----Original Message-----
> From: Shawn Lin <shawn.lin@linux.dev> 
> Sent: Thursday, March 12, 2026 3:25 AM
> To: Hawkins, Nick <nick.hawkins@hpe.com>; ulf.hansson@linaro.org; adrian.hunter@intel.com; jszhang@kernel.org
> Cc: shawn.lin@linux.dev; robh@kernel.org; krzk+dt@kernel.org; conor+dt@kernel.org; shawn.lin@rock-chips.com; linux-mmc@vger.kernel.org; devicetree@vger.kernel.org; linux-kernel@vger.kernel.org
> Subject: Re: [PATCH v3 2/2] mmc: sdhci-of-dwcmshc: Add HPE GSC eMMC support


> > +static int dwcmshc_hpe_gsc_init(struct device *dev, struct sdhci_host *host,
> > +				struct dwcmshc_priv *dwc_priv)
> > +{
> > +	struct regmap *soc_ctrl;
> > +	int ret;
> > +
> > +	/* Disable cmd conflict check and configure auto-tuning */
> > +	dwcmshc_hpe_vendor_specific(host);
> > +
> > +	/* Look up the GXP sysreg syscon for MSHCCS access */
> > +	soc_ctrl = syscon_regmap_lookup_by_phandle(dev->of_node, "hpe,gxp-sysreg");
> > +	if (IS_ERR(soc_ctrl)) {
> > +		dev_err(dev, "failed to get hpe,gxp-sysreg syscon\n");
> > +		return PTR_ERR(soc_ctrl);
> > +	}
> > +
> > +	/* Set SCGSyncDis (bit 18) to disable sync on HS200 RX delay lines */
> > +	ret = regmap_update_bits(soc_ctrl, HPE_GSC_MSHCCS_OFFSET,
> > +				HPE_GSC_MSHCCS_SCGSYNCDIS,
> > +				HPE_GSC_MSHCCS_SCGSYNCDIS);
> > +	if (ret) {
> > +		dev_err(dev, "failed to set SCGSyncDis in MSHCCS\n");
> > +		return ret;
> > +	}
> > +
> > +	sdhci_enable_v4_mode(host);

> Sorry, I overlooked this part when in v2. But we enable it in
> dwcmshc_probe() based on the capabilities, isn't it? Unless your
> hardware didn't set SDHCI_CAN_64BIT_V4 but actually it does support
> it? Then it perhaps should be a quirk, although we in general would like
> to avoid more quirks... It depends on Adrian.

> Btw, unlated to your patch, but th1520 did it the same way... Hmm

The GSC's IP is configured with a 32-bit DMA AXI
interface, so SDHCI_CAN_64BIT_V4 (caps bit 27) is not set by the
hardware. However, the controller still requires Host V4 mode
(HOST_CTRL2_R bit 12) to be enabled. Since dwcmshc_probe()
only calls sdhci_enable_v4_mode() when SDHCI_CAN_64BIT_V4
is set, the explicit call in dwcmshc_hpe_gsc_init() is necessary.

Thanks,

-Nick H


 

Re: [PATCH v3 2/2] mmc: sdhci-of-dwcmshc: Add HPE GSC eMMC support

[Shawn Lin]

在 2026/03/13 星期五 3:25, Hawkins, Nick 写道:
> Hi Shawn, thank you for your input.
> 
> See below:
> 
>> -----Original Message-----
>> From: Shawn Lin <shawn.lin@linux.dev>
>> Sent: Thursday, March 12, 2026 3:25 AM
>> To: Hawkins, Nick <nick.hawkins@hpe.com>; ulf.hansson@linaro.org; adrian.hunter@intel.com; jszhang@kernel.org
>> Cc: shawn.lin@linux.dev; robh@kernel.org; krzk+dt@kernel.org; conor+dt@kernel.org; shawn.lin@rock-chips.com; linux-mmc@vger.kernel.org; devicetree@vger.kernel.org; linux-kernel@vger.kernel.org
>> Subject: Re: [PATCH v3 2/2] mmc: sdhci-of-dwcmshc: Add HPE GSC eMMC support
> 
> 
>>> +static int dwcmshc_hpe_gsc_init(struct device *dev, struct sdhci_host *host,
>>> +				struct dwcmshc_priv *dwc_priv)
>>> +{
>>> +	struct regmap *soc_ctrl;
>>> +	int ret;
>>> +
>>> +	/* Disable cmd conflict check and configure auto-tuning */
>>> +	dwcmshc_hpe_vendor_specific(host);
>>> +
>>> +	/* Look up the GXP sysreg syscon for MSHCCS access */
>>> +	soc_ctrl = syscon_regmap_lookup_by_phandle(dev->of_node, "hpe,gxp-sysreg");
>>> +	if (IS_ERR(soc_ctrl)) {
>>> +		dev_err(dev, "failed to get hpe,gxp-sysreg syscon\n");
>>> +		return PTR_ERR(soc_ctrl);
>>> +	}
>>> +
>>> +	/* Set SCGSyncDis (bit 18) to disable sync on HS200 RX delay lines */
>>> +	ret = regmap_update_bits(soc_ctrl, HPE_GSC_MSHCCS_OFFSET,
>>> +				HPE_GSC_MSHCCS_SCGSYNCDIS,
>>> +				HPE_GSC_MSHCCS_SCGSYNCDIS);
>>> +	if (ret) {
>>> +		dev_err(dev, "failed to set SCGSyncDis in MSHCCS\n");
>>> +		return ret;
>>> +	}
>>> +
>>> +	sdhci_enable_v4_mode(host);
> 
>> Sorry, I overlooked this part when in v2. But we enable it in
>> dwcmshc_probe() based on the capabilities, isn't it? Unless your
>> hardware didn't set SDHCI_CAN_64BIT_V4 but actually it does support
>> it? Then it perhaps should be a quirk, although we in general would like
>> to avoid more quirks... It depends on Adrian.
> 
>> Btw, unlated to your patch, but th1520 did it the same way... Hmm
> 
> The GSC's IP is configured with a 32-bit DMA AXI
> interface, so SDHCI_CAN_64BIT_V4 (caps bit 27) is not set by the
> hardware. However, the controller still requires Host V4 mode
> (HOST_CTRL2_R bit 12) to be enabled. Since dwcmshc_probe()
> only calls sdhci_enable_v4_mode() when SDHCI_CAN_64BIT_V4
> is set, the explicit call in dwcmshc_hpe_gsc_init() is necessary.

Okay, this aligns with previous assumption. So, we should either handle 
it via a quirk in the probe function and remove the call here, or simply 
add a comment to explain the context. This depends on Adrian's 
preference. I have no further questions. Thanks

> 
> Thanks,
> 
> -Nick H
> 
> 
>   
> 

Re: [PATCH v3 2/2] mmc: sdhci-of-dwcmshc: Add HPE GSC eMMC support

[Adrian Hunter]

On 13/03/2026 04:10, Shawn Lin wrote:
> 在 2026/03/13 星期五 3:25, Hawkins, Nick 写道:
>> Hi Shawn, thank you for your input.
>>
>> See below:
>>
>>> -----Original Message-----
>>> From: Shawn Lin <shawn.lin@linux.dev>
>>> Sent: Thursday, March 12, 2026 3:25 AM
>>> To: Hawkins, Nick <nick.hawkins@hpe.com>; ulf.hansson@linaro.org; adrian.hunter@intel.com; jszhang@kernel.org
>>> Cc: shawn.lin@linux.dev; robh@kernel.org; krzk+dt@kernel.org; conor+dt@kernel.org; shawn.lin@rock-chips.com; linux-mmc@vger.kernel.org; devicetree@vger.kernel.org; linux-kernel@vger.kernel.org
>>> Subject: Re: [PATCH v3 2/2] mmc: sdhci-of-dwcmshc: Add HPE GSC eMMC support
>>
>>
>>>> +static int dwcmshc_hpe_gsc_init(struct device *dev, struct sdhci_host *host,
>>>> +                struct dwcmshc_priv *dwc_priv)
>>>> +{
>>>> +    struct regmap *soc_ctrl;
>>>> +    int ret;
>>>> +
>>>> +    /* Disable cmd conflict check and configure auto-tuning */
>>>> +    dwcmshc_hpe_vendor_specific(host);
>>>> +
>>>> +    /* Look up the GXP sysreg syscon for MSHCCS access */
>>>> +    soc_ctrl = syscon_regmap_lookup_by_phandle(dev->of_node, "hpe,gxp-sysreg");
>>>> +    if (IS_ERR(soc_ctrl)) {
>>>> +        dev_err(dev, "failed to get hpe,gxp-sysreg syscon\n");
>>>> +        return PTR_ERR(soc_ctrl);
>>>> +    }
>>>> +
>>>> +    /* Set SCGSyncDis (bit 18) to disable sync on HS200 RX delay lines */
>>>> +    ret = regmap_update_bits(soc_ctrl, HPE_GSC_MSHCCS_OFFSET,
>>>> +                HPE_GSC_MSHCCS_SCGSYNCDIS,
>>>> +                HPE_GSC_MSHCCS_SCGSYNCDIS);
>>>> +    if (ret) {
>>>> +        dev_err(dev, "failed to set SCGSyncDis in MSHCCS\n");
>>>> +        return ret;
>>>> +    }
>>>> +
>>>> +    sdhci_enable_v4_mode(host);
>>
>>> Sorry, I overlooked this part when in v2. But we enable it in
>>> dwcmshc_probe() based on the capabilities, isn't it? Unless your
>>> hardware didn't set SDHCI_CAN_64BIT_V4 but actually it does support
>>> it? Then it perhaps should be a quirk, although we in general would like
>>> to avoid more quirks... It depends on Adrian.
>>
>>> Btw, unlated to your patch, but th1520 did it the same way... Hmm
>>
>> The GSC's IP is configured with a 32-bit DMA AXI
>> interface, so SDHCI_CAN_64BIT_V4 (caps bit 27) is not set by the
>> hardware. However, the controller still requires Host V4 mode
>> (HOST_CTRL2_R bit 12) to be enabled. Since dwcmshc_probe()
>> only calls sdhci_enable_v4_mode() when SDHCI_CAN_64BIT_V4
>> is set, the explicit call in dwcmshc_hpe_gsc_init() is necessary.
> 
> Okay, this aligns with previous assumption. So, we should either handle it via a quirk in the probe function and remove the call here, or simply add a comment to explain the context. This depends on Adrian's preference. I have no further questions. Thanks

Since ->init() is needed anyway, adding extra logic to handle
sdhci_enable_v4_mode() separately doesn't reduce complexity,
so I would leave it.

Re: [PATCH v3 2/2] mmc: sdhci-of-dwcmshc: Add HPE GSC eMMC support

[Adrian Hunter]

On 11/03/2026 20:11, nick.hawkins@hpe.com wrote:
> From: Nick Hawkins <nick.hawkins@hpe.com>
> 
> Add support for the eMMC controller integrated in the HPE GSC (ARM64
> Cortex-A53) BMC SoC under the new 'hpe,gsc-dwcmshc' compatible
> string.
> 
> The HPE GSC eMMC controller is based on the DesignWare Cores MSHC IP
> but requires several platform-specific adjustments:
> 
> Clock mux (dwcmshc_hpe_set_clock):
>   The GSC SoC wires SDHCI_CLOCK_CONTROL.freq_sel directly to a clock
>   mux rather than a divider.  Forcing freq_sel = 1 when the requested
>   clock is 200 MHz (HS200) selects the correct high-speed clock source.
>   Using the generic sdhci_set_clock() would otherwise leave the mux on
>   the wrong source after tuning.
> 
> Auto-tuning / vendor config (dwcmshc_hpe_vendor_specific):
>   Disables the command-conflict check (DWCMSHC_HOST_CTRL3 BIT(0)) and
>   programs the ATCTRL register using existing AT_CTRL_* macros:
>     AT_CTRL_AT_EN           auto-tuning circuit enable
>     AT_CTRL_SWIN_TH_EN      sampling window threshold enable
>     AT_CTRL_TUNE_CLK_STOP_EN tune-clock-stop enable
>     PRE_CHANGE_DLY  = 3     pre-change delay
>     POST_CHANGE_DLY = 3     post-change delay
>     SWIN_TH_VAL    = 2      sampling window threshold
>   This combination is required for reliable HS200 signal integrity on
>   the GSC PCB trace topology.
> 
> Reset (dwcmshc_hpe_reset):
>   Calls sdhci_reset(), re-applies the vendor config above, and then
>   sets DWCMSHC_CARD_IS_EMMC unconditionally.  The GSC controller
>   clears this bit on every reset; leaving it clear causes card-detect
>   mis-identification on an eMMC-only slot.
> 
> UHS signaling (dwcmshc_hpe_set_uhs_signaling):
>   Wraps dwcmshc_set_uhs_signaling() and unconditionally sets
>   CARD_IS_EMMC for all timing modes, not just HS400.
> 
> Init (dwcmshc_hpe_gsc_init):
>   Obtains the SoC register block via the 'hpe,gxp-sysreg' syscon
>   phandle and sets SCGSyncDis (BIT(18)) in MSHCCS (offset 0x110)
>   to allow the HS200 RX delay lines to settle while the card clock
>   is stopped during auto-tuning.  Enables SDHCI v4 mode.
> 
> Quirks:
>   SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN:  base clock not advertised in
>     capabilities; must be obtained from the DTS 'clocks' property.
>   SDHCI_QUIRK2_PRESET_VALUE_BROKEN:  preset-value registers are not
>     populated in the GSC ROM.
> 
> All HPE-specific code is isolated to the new hpe_gsc_init / hpe_ops /
> hpe_gsc_pdata symbols.  No existing platform (Rockchip, T-Head, sg2042,
> etc.) is affected.
> 
> Signed-off-by: Nick Hawkins <nick.hawkins@hpe.com>
> ---
>  drivers/mmc/host/sdhci-of-dwcmshc.c | 149 ++++++++++++++++++++++++++++
>  1 file changed, 149 insertions(+)
> 
> diff --git a/drivers/mmc/host/sdhci-of-dwcmshc.c b/drivers/mmc/host/sdhci-of-dwcmshc.c
> index 2b75a36c096b..46662071cc61 100644
> --- a/drivers/mmc/host/sdhci-of-dwcmshc.c
> +++ b/drivers/mmc/host/sdhci-of-dwcmshc.c
> @@ -1245,6 +1245,132 @@ static int sg2042_init(struct device *dev, struct sdhci_host *host,
>  					     ARRAY_SIZE(clk_ids), clk_ids);
>  }
>  
> +/* HPE GSC-specific vendor configuration: disable command conflict check
> + * and program Auto-Tuning Control register.
> + */

In this file, multiline comments use the slightly longer form:

	/*
	 * HPE GSC-specific vendor configuration: disable command conflict check
	 * and program Auto-Tuning Control register.
	 */

> +static void dwcmshc_hpe_vendor_specific(struct sdhci_host *host)
> +{
> +	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> +	struct dwcmshc_priv *dwc_priv = sdhci_pltfm_priv(pltfm_host);
> +	u32 atctrl;
> +	u8 extra;
> +
> +	extra = sdhci_readb(host, dwc_priv->vendor_specific_area1 + DWCMSHC_HOST_CTRL3);
> +	extra &= ~BIT(0);

BIT(0)?

> +	sdhci_writeb(host, extra, dwc_priv->vendor_specific_area1 + DWCMSHC_HOST_CTRL3);
> +
> +	atctrl = AT_CTRL_AT_EN | AT_CTRL_SWIN_TH_EN | AT_CTRL_TUNE_CLK_STOP_EN |
> +		FIELD_PREP(AT_CTRL_PRE_CHANGE_DLY_MASK, 3) |
> +		FIELD_PREP(AT_CTRL_POST_CHANGE_DLY_MASK, AT_CTRL_POST_CHANGE_DLY) |
> +		FIELD_PREP(AT_CTRL_SWIN_TH_VAL_MASK, 2);
> +	sdhci_writel(host, atctrl, dwc_priv->vendor_specific_area1 + DWCMSHC_EMMC_ATCTRL);
> +}
> +
> +static void dwcmshc_hpe_reset(struct sdhci_host *host, u8 mask)
> +{
> +	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> +	struct dwcmshc_priv *dwc_priv = sdhci_pltfm_priv(pltfm_host);
> +	u16 ctrl;
> +
> +	dwcmshc_reset(host, mask);
> +
> +	dwcmshc_hpe_vendor_specific(host);
> +
> +	/* HPE GSC eMMC always needs CARD_IS_EMMC set after reset */
> +	ctrl = sdhci_readw(host, dwc_priv->vendor_specific_area1 + DWCMSHC_EMMC_CONTROL);
> +	ctrl |= DWCMSHC_CARD_IS_EMMC;
> +	sdhci_writew(host, ctrl, dwc_priv->vendor_specific_area1 + DWCMSHC_EMMC_CONTROL);
> +}
> +
> +static void dwcmshc_hpe_set_uhs_signaling(struct sdhci_host *host,
> +					  unsigned int timing)
> +{
> +	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> +	struct dwcmshc_priv *priv = sdhci_pltfm_priv(pltfm_host);
> +	u16 ctrl;
> +
> +	dwcmshc_set_uhs_signaling(host, timing);
> +
> +	/* HPE GSC: always set CARD_IS_EMMC for all timing modes */
> +	ctrl = sdhci_readw(host, priv->vendor_specific_area1 + DWCMSHC_EMMC_CONTROL);
> +	ctrl |= DWCMSHC_CARD_IS_EMMC;
> +	sdhci_writew(host, ctrl, priv->vendor_specific_area1 + DWCMSHC_EMMC_CONTROL);

Might be neater as a separate helper function that can be called from
dwcmshc_hpe_reset() also

> +}
> +
> +/*
> + * HPE GSC eMMC controller clock setup.
> + *
> + * The GSC SoC wires the freq_sel field of SDHCI_CLOCK_CONTROL directly to a
> + * clock mux rather than a divider. Force freq_sel = 1 when running at
> + * 200 MHz (HS200) so the mux selects the correct clock source.
> + */
> +static void dwcmshc_hpe_set_clock(struct sdhci_host *host, unsigned int clock)
> +{
> +	u16 clk;
> +
> +	host->mmc->actual_clock = 0;
> +
> +	sdhci_writew(host, 0, SDHCI_CLOCK_CONTROL);
> +
> +	if (clock == 0)
> +		return;
> +
> +	clk = sdhci_calc_clk(host, clock, &host->mmc->actual_clock);
> +
> +	if (host->mmc->actual_clock == 200000000)
> +		clk |= (1 << SDHCI_DIVIDER_SHIFT);
> +
> +	sdhci_enable_clk(host, clk);
> +}
> +
> +/*
> + * HPE GSC eMMC controller init.
> + *
> + * The GSC SoC requires configuring MSHCCS.  Bit 18 (SCGSyncDis) disables clock
> + * synchronisation for phase-select values going to the HS200 RX delay lines,
> + * allowing the card clock to be stopped while the delay selection settles and
> + * the phase shift is applied.  This must be used together with the ATCTRL
> + * settings programmed in dwcmshc_hpe_vendor_specific():
> + *   AT_CTRL_R.TUNE_CLK_STOP_EN  = 0x1
> + *   AT_CTRL_R.POST_CHANGE_DLY   = 0x3
> + *   AT_CTRL_R.PRE_CHANGE_DLY    = 0x3
> + *
> + * The DTS node provides a syscon phandle ('hpe,gxp-sysreg') to access
> + * this register at offset 0x110 within the SoC control block.
> + */
> +#define HPE_GSC_MSHCCS_OFFSET		0x110
> +#define HPE_GSC_MSHCCS_SCGSYNCDIS	BIT(18)
> +
> +static int dwcmshc_hpe_gsc_init(struct device *dev, struct sdhci_host *host,
> +				struct dwcmshc_priv *dwc_priv)
> +{
> +	struct regmap *soc_ctrl;
> +	int ret;
> +
> +	/* Disable cmd conflict check and configure auto-tuning */
> +	dwcmshc_hpe_vendor_specific(host);
> +
> +	/* Look up the GXP sysreg syscon for MSHCCS access */
> +	soc_ctrl = syscon_regmap_lookup_by_phandle(dev->of_node, "hpe,gxp-sysreg");
> +	if (IS_ERR(soc_ctrl)) {
> +		dev_err(dev, "failed to get hpe,gxp-sysreg syscon\n");
> +		return PTR_ERR(soc_ctrl);
> +	}
> +
> +	/* Set SCGSyncDis (bit 18) to disable sync on HS200 RX delay lines */
> +	ret = regmap_update_bits(soc_ctrl, HPE_GSC_MSHCCS_OFFSET,
> +				HPE_GSC_MSHCCS_SCGSYNCDIS,
> +				HPE_GSC_MSHCCS_SCGSYNCDIS);

Doesn't quite line up

> +	if (ret) {
> +		dev_err(dev, "failed to set SCGSyncDis in MSHCCS\n");
> +		return ret;
> +	}
> +
> +	sdhci_enable_v4_mode(host);
> +
> +	return 0;
> +}
> +
>  static void sdhci_eic7700_set_clock(struct sdhci_host *host, unsigned int clock)
>  {
>  	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> @@ -1834,6 +1960,25 @@ static const struct dwcmshc_pltfm_data sdhci_dwcmshc_eic7700_pdata = {
>  	.init = eic7700_init,
>  };
>  
> +static const struct sdhci_ops sdhci_dwcmshc_hpe_ops = {
> +	.set_clock		= dwcmshc_hpe_set_clock,
> +	.set_bus_width		= sdhci_set_bus_width,
> +	.set_uhs_signaling	= dwcmshc_hpe_set_uhs_signaling,
> +	.get_max_clock		= dwcmshc_get_max_clock,
> +	.reset			= dwcmshc_hpe_reset,
> +	.adma_write_desc	= dwcmshc_adma_write_desc,
> +	.irq			= dwcmshc_cqe_irq_handler,
> +};
> +
> +static const struct dwcmshc_pltfm_data sdhci_dwcmshc_hpe_gsc_pdata = {
> +	.pdata = {
> +		.ops = &sdhci_dwcmshc_hpe_ops,
> +		.quirks = SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN,
> +		.quirks2 = SDHCI_QUIRK2_PRESET_VALUE_BROKEN,
> +	},
> +	.init = dwcmshc_hpe_gsc_init,
> +};
> +
>  static const struct cqhci_host_ops dwcmshc_cqhci_ops = {
>  	.enable		= dwcmshc_sdhci_cqe_enable,
>  	.disable	= sdhci_cqe_disable,
> @@ -1942,6 +2087,10 @@ static const struct of_device_id sdhci_dwcmshc_dt_ids[] = {
>  		.compatible = "eswin,eic7700-dwcmshc",
>  		.data = &sdhci_dwcmshc_eic7700_pdata,
>  	},
> +	{
> +		.compatible = "hpe,gsc-dwcmshc",
> +		.data = &sdhci_dwcmshc_hpe_gsc_pdata,
> +	},
>  	{},
>  };
>  MODULE_DEVICE_TABLE(of, sdhci_dwcmshc_dt_ids);