Re: [PATCH v2 2/9] phy: stm32: Add support for ST STM32MP25 USB2-FEMTO PHY

On 8/17/26 6:22 PM, Fabrice Gasnier wrote:

Hello Fabrice,

quoted

+++ b/drivers/phy/st/phy-stm32-usb2phy.c

@@ -0,0 +1,361 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * STMicroelectronics STM32 USB2 PHY Controller driver
+ * Currently Only supported for STM32MP25
+ *
+ * Copyright (C) 2022 STMicroelectronics

Hi Marek,

Could update to 2026 ?

Fixed in V3.

[...]

quoted

+static int stm32_usb2phy_enable(struct stm32_usb2phy *phy_dev)
+{
+	const struct stm32mp2_usb2phy_hw_data *phy_data = phy_dev->hw_data;
+	unsigned long rate;
+	int refsel, ret;
+
+	/* Check if a phy is already init or clk48 in use */
+	if (atomic_inc_return(&phy_dev->en_refcnt) > 1)
+		return 0;
+
+	rate = clk_get_rate(phy_dev->phyref);
+	if (rate == 19200000)
+		refsel = 0;
+	else if (rate == 20000000)
+		refsel = 1;
+	else if (rate == 24000000)
+		refsel = 2;
+	else
+		return -EINVAL;
+
+	ret = regmap_update_bits(phy_dev->regmap,
+				 phy_dev->cr_offset,
+				 phy_data->phyrefsel_mask,
+				 field_prep(phy_data->phyrefsel_mask, refsel));
+	if (ret)
+		return ret;
+

Hi Marek,

Below condition

quoted

+	if (phy_data->is_usb2_host_only) {
+		/*
+		 * The clock should default to active after standby, as it is
+		 * needed when resuming OHCI to access its registers.
+		 * CMN is default reset to 1, so enforce it is cleared, when the
+		 * clock enable request from OHCI driver comes at resume time.
+		 */
+		ret = regmap_clear_bits(phy_dev->regmap, phy_dev->cr_offset,
+					SYSCFG_USB2PHY2CR_USB2PHY2CMN);
+		if (ret)
+			return ret;
+	}

up to here, is a specific part to manage OHCI controller clock during
suspend modes (either bus suspend, or system-wide platform low power PM).

This should be moved to the clock provider api. E.g. to register a 2nd
clock.

Point here is the bit is always cleared, even if OHCI is
unused/disabled, but EHCI is. EHCI can be enabled w/o OHCI when there's
an on-board USB HUB (in such case only High Speed traffic is expected).

EHCI don't require to clear CMN for suspend states.

Please see at the end of this email.

quoted

+
+	ret = regulator_enable(phy_dev->vdd33);
+	if (ret)
+		return ret;

[...]

quoted

+static int stm32_usb2phy_set_mode(struct phy *phy, enum phy_mode mode, int submode)
+{
+	struct stm32_usb2phy *phy_dev = phy_get_drvdata(phy);
+	const struct stm32mp2_usb2phy_hw_data *phy_data = phy_dev->hw_data;
+	u32 val, mask = SYSCFG_USB2PHY2CR_USB2PHY2CMN;
+	int ret;

Then could simplify here directly for host only PHY : there's no point
in poking control register here.
(As mentioned above, control SYSCFG_USB2PHY2CR_USB2PHY2CMN with clock
provider API for host-only configuration.)

	if (phy_data->is_usb2_host_only)
		return 0;

I think it would be even better at this point to register separate PHY 
ops for each PHY, one with and one without .set_mode .

[...]

quoted

+	ret = devm_clk_hw_register(phy_dev->dev, &phy_dev->clk48_hw);
+	if (ret)
+		return dev_err_probe(phy_dev->dev, ret, "Failed to register 48 MHz clock\n");

In v2, the #clock-cells has been updated to 1. This allow to manage
separately the OHCI clock bit ("...CMN") as a child clock of the 48MHz
clock.

Please register a 2nd clock, so the OHCI controller can take benefit of it.

As you mention the downstream driver, please see there a specific
comment regarding the 2nd clock for OHCI:
/*
* USB2PHY provides several clocks used either by either USHB
(EHCI/OHCI), OTG or USB3DR.
* In case of OHCI, CMN bit must be cleared (clkohci_hw). This clock is
required to access
* the registers, to resume the controller from suspended state.
* So declare two clocks, the PLL used in all case, and the OHCI clocks
used by OHCI
* controller.
*/

Is this what you have in mind ?

diff --git a/arch/arm64/boot/dts/st/stm32mp231.dtsi 

b/arch/arm64/boot/dts/st/stm32mp231.dtsi
index e22bb53c9748b..2fa03b059c71b 100644

--- a/arch/arm64/boot/dts/st/stm32mp231.dtsi
+++ b/arch/arm64/boot/dts/st/stm32mp231.dtsi

@@ -883,7 +883,7 @@ usbh_ohci: usb@482e0000 {
  				compatible = "generic-ohci";
  				reg = <0x482e0000 0x1000>;
  				access-controllers = <&rifsc 63>;
-				clocks = <&usb2_phy1 0>, <&rcc CK_BUS_USB2OHCI>;
+				clocks = <&usb2_phy1 1>, <&rcc CK_BUS_USB2OHCI>;
  				interrupts = <GIC_SPI 140 IRQ_TYPE_LEVEL_HIGH>;
  				phys = <&usb2_phy1>;
  				phy-names = "usb";

diff --git a/arch/arm64/boot/dts/st/stm32mp251.dtsi 

b/arch/arm64/boot/dts/st/stm32mp251.dtsi
index dbaac8a930fda..6e0f25e33f05f 100644

--- a/arch/arm64/boot/dts/st/stm32mp251.dtsi
+++ b/arch/arm64/boot/dts/st/stm32mp251.dtsi

@@ -1765,7 +1765,7 @@ usbh_ohci: usb@482e0000 {
  				compatible = "generic-ohci";
  				reg = <0x482e0000 0x1000>;
  				access-controllers = <&rifsc 63>;
-				clocks = <&usb2_phy1 0>, <&rcc CK_BUS_USB2OHCI>;
+				clocks = <&usb2_phy1 1>, <&rcc CK_BUS_USB2OHCI>;
  				interrupts = <GIC_SPI 140 IRQ_TYPE_LEVEL_HIGH>;
  				phys = <&usb2_phy1>;
  				phy-names = "usb";

diff --git a/drivers/phy/st/phy-stm32-usb2phy.c 

b/drivers/phy/st/phy-stm32-usb2phy.c
index 1daaf2f440d04..1c4b37094591c 100644

--- a/drivers/phy/st/phy-stm32-usb2phy.c
+++ b/drivers/phy/st/phy-stm32-usb2phy.c

@@ -27,6 +27,8 @@
  #define SYSCFG_USB2PHY2CR_VBUSVLDEXTSEL		BIT(5)
  #define SYSCFG_USB2PHY2CR_VBUSVLDEXT		BIT(6)

+#define USBH_NUM_CLK				2
+
  struct stm32_usb2phy {
  	struct phy				*phy;
  	struct regmap				*regmap;

@@ -34,12 +36,15 @@ struct stm32_usb2phy {
  	struct reset_control			*rstc;
  	struct clk				*phyref;
  	struct regulator			*vdd33;
-	struct clk_hw				clk48_hw;
  	const struct stm32mp2_usb2phy_hw_data	*hw_data;
  	atomic_t				en_refcnt;
  	enum phy_mode				mode;
  	u32					cr_offset;
  	bool					is_init;
+	struct clk_hw				clk48_hw;
+	struct clk_hw				clkcmn_hw;
+	/* Must be last */
+	struct clk_hw_onecell_data		onecell;
  };

  struct stm32mp2_usb2phy_hw_data {

@@ -74,19 +79,6 @@ static int stm32_usb2phy_enable(struct stm32_usb2phy 

*phy_dev)
  	if (ret)
  		return ret;

-	if (phy_data->is_usb2_host_only) {
-		/*
-		 * The clock should default to active after standby, as it is
-		 * needed when resuming OHCI to access its registers.
-		 * CMN is default reset to 1, so enforce it is cleared, when the
-		 * clock enable request from OHCI driver comes at resume time.
-		 */
-		ret = regmap_clear_bits(phy_dev->regmap, phy_dev->cr_offset,
-					SYSCFG_USB2PHY2CR_USB2PHY2CMN);
-		if (ret)
-			return ret;
-	}
-
  	ret = regulator_enable(phy_dev->vdd33);
  	if (ret)
  		return ret;

@@ -233,9 +225,33 @@ static const struct clk_ops stm32_usb2phy_clk48_ops = {
  	.recalc_rate = stm32_usb2phy_clk48_recalc_rate,
  };

+static int stm32_usb2phy_clkcmn_prepare(struct clk_hw *hw)
+{
+	struct stm32_usb2phy *phy_dev = container_of(hw, struct stm32_usb2phy,
+						     clkcmn_hw);
+
+	return regmap_clear_bits(phy_dev->regmap, phy_dev->cr_offset,
+				 SYSCFG_USB2PHY2CR_USB2PHY2CMN);
+}
+
+static void stm32_usb2phy_clkcmn_unprepare(struct clk_hw *hw)
+{
+	struct stm32_usb2phy *phy_dev = container_of(hw, struct stm32_usb2phy,
+						     clkcmn_hw);
+
+	regmap_set_bits(phy_dev->regmap, phy_dev->cr_offset,
+			SYSCFG_USB2PHY2CR_USB2PHY2CMN);
+}
+
+static const struct clk_ops stm32_usb2phy_clkcmn_ops = {
+	.prepare = stm32_usb2phy_clkcmn_prepare,
+	.unprepare = stm32_usb2phy_clkcmn_unprepare,
+};
+
  static int stm32_usb2phy_probe(struct platform_device *pdev)
  {
-	struct clk_init_data init = { .ops =  &stm32_usb2phy_clk48_ops };
+	struct clk_init_data clk48init = { .ops =  &stm32_usb2phy_clk48_ops };
+	struct clk_init_data clkcmninit = { .ops =  &stm32_usb2phy_clkcmn_ops };
  	struct phy_provider *phy_provider;
  	struct device *dev = &pdev->dev;
  	struct stm32_usb2phy *phy_dev;

@@ -243,7 +259,7 @@ static int stm32_usb2phy_probe(struct 

platform_device *pdev)
  	struct phy *phy;
  	int ret;

-	phy_dev = devm_kzalloc(dev, sizeof(*phy_dev), GFP_KERNEL);
+	phy_dev = devm_kzalloc(dev, struct_size(phy_dev, onecell.hws, 
USBH_NUM_CLK), GFP_KERNEL);
  	if (!phy_dev)
  		return -ENOMEM;

@@ -285,20 +301,33 @@ static int stm32_usb2phy_probe(struct 

platform_device *pdev)
  	if (IS_ERR(phy_provider))
  		return PTR_ERR(phy_provider);

-	init.name = devm_kasprintf(dev, GFP_KERNEL, "clk_%s_48m",
+	clk48init.name = devm_kasprintf(dev, GFP_KERNEL, "clk_%s_48m",
  				   of_node_full_name(dev->of_node));
-	if (!init.name)
+	if (!clk48init.name)
  		return -ENOMEM;

-	phy_dev->clk48_hw.init = &init;
+	clkcmninit.name = devm_kasprintf(dev, GFP_KERNEL, "clk_%s_cmn",
+				   of_node_full_name(dev->of_node));
+	if (!clkcmninit.name)
+		return -ENOMEM;
+
+	phy_dev->onecell.num = USBH_NUM_CLK;
+	phy_dev->onecell.hws[0] = &phy_dev->clk48_hw;
+	phy_dev->onecell.hws[1] = &phy_dev->clkcmn_hw;

+	phy_dev->clk48_hw.init = &clk48init;
  	ret = devm_clk_hw_register(phy_dev->dev, &phy_dev->clk48_hw);
  	if (ret)
  		return dev_err_probe(phy_dev->dev, ret, "Failed to register 48 MHz 
clock\n");

-	ret = devm_of_clk_add_hw_provider(phy_dev->dev, of_clk_hw_simple_get, 
&phy_dev->clk48_hw);
+	phy_dev->clkcmn_hw.init = &clkcmninit;
+	ret = devm_clk_hw_register(phy_dev->dev, &phy_dev->clkcmn_hw);
+	if (ret)
+		return dev_err_probe(phy_dev->dev, ret, "Failed to register CMN 
clock\n");
+
+	ret = devm_of_clk_add_hw_provider(phy_dev->dev, of_clk_hw_onecell_get, 
&phy_dev->onecell);
  	if (ret)
-		return dev_err_probe(phy_dev->dev, ret, "Failed to add 48 MHz clock 
provider\n");
+		return dev_err_probe(phy_dev->dev, ret, "Failed to add clock 
provider\n");

  	return 0;
  }