[PATCH v2 3/4] usb: dwc2: platform: add support for utmi optional clock

[Fabrice Gasnier <fabrice.gasnier@xxxxxxxxxxx>]

Add support for the utmi clock. It's needed on STM32MP15, when using
the integrated full-speed PHY. This clock is an output of USBPHYC, but
HS USBPHYC is not attached as PHY in this case: Full-Speed PHY is directly
managed in dwc2 glue, through GGPIO register. Typical DT when using FS PHY
&usbotg_hs {
	compatible = "st,stm32mp15-fsotg", "snps,dwc2";
	pinctrl-names = "default";
	pinctrl-0 = <&usbotg_hs_pins_a &usbotg_fs_dp_dm_pins_a>;
	vbus-supply = <&vbus_otg>;
	status = "okay";
};

In this configuration, USBPHYC clock output must be defined, so it can
be properly enabled as a clock provider:
	clocks = <&rcc USBO_K>, <&usbphyc>;
	clock-names = "otg", "utmi";

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@xxxxxxxxxxx>
---
Changes in v2:
- "utmi_clk" renamed "utmi" as per Krzysztof comment on dt-bindings
---
 drivers/usb/dwc2/core.h     |  2 ++
 drivers/usb/dwc2/platform.c | 20 +++++++++++++++++++-
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/dwc2/core.h b/drivers/usb/dwc2/core.h
index 40cf2880d7e5..0bb4c0c845bf 100644
--- a/drivers/usb/dwc2/core.h
+++ b/drivers/usb/dwc2/core.h
@@ -1003,6 +1003,7 @@ struct dwc2_hregs_backup {
  * @ctrl_out_desc:	EP0 OUT data phase desc chain pointer
  * @irq:		Interrupt request line number
  * @clk:		Pointer to otg clock
+ * @utmi_clk:		Pointer to utmi_clk clock
  * @reset:		Pointer to dwc2 reset controller
  * @reset_ecc:          Pointer to dwc2 optional reset controller in Stratix10.
  * @regset:		A pointer to a struct debugfs_regset32, which contains
@@ -1065,6 +1066,7 @@ struct dwc2_hsotg {
 	void *priv;
 	int     irq;
 	struct clk *clk;
+	struct clk *utmi_clk;
 	struct reset_control *reset;
 	struct reset_control *reset_ecc;
 
diff --git a/drivers/usb/dwc2/platform.c b/drivers/usb/dwc2/platform.c
index c431ce6c119f..5aee284018c0 100644
--- a/drivers/usb/dwc2/platform.c
+++ b/drivers/usb/dwc2/platform.c
@@ -101,10 +101,16 @@ static int __dwc2_lowlevel_hw_enable(struct dwc2_hsotg *hsotg)
 	if (ret)
 		return ret;
 
+	if (hsotg->utmi_clk) {
+		ret = clk_prepare_enable(hsotg->utmi_clk);
+		if (ret)
+			goto err_dis_reg;
+	}
+
 	if (hsotg->clk) {
 		ret = clk_prepare_enable(hsotg->clk);
 		if (ret)
-			goto err_dis_reg;
+			goto err_dis_utmi_clk;
 	}
 
 	if (hsotg->uphy) {
@@ -129,6 +135,10 @@ static int __dwc2_lowlevel_hw_enable(struct dwc2_hsotg *hsotg)
 	if (hsotg->clk)
 		clk_disable_unprepare(hsotg->clk);
 
+err_dis_utmi_clk:
+	if (hsotg->utmi_clk)
+		clk_disable_unprepare(hsotg->utmi_clk);
+
 err_dis_reg:
 	regulator_bulk_disable(ARRAY_SIZE(hsotg->supplies), hsotg->supplies);
 
@@ -171,6 +181,9 @@ static int __dwc2_lowlevel_hw_disable(struct dwc2_hsotg *hsotg)
 	if (hsotg->clk)
 		clk_disable_unprepare(hsotg->clk);
 
+	if (hsotg->utmi_clk)
+		clk_disable_unprepare(hsotg->utmi_clk);
+
 	return regulator_bulk_disable(ARRAY_SIZE(hsotg->supplies), hsotg->supplies);
 }
 
@@ -247,6 +260,11 @@ static int dwc2_lowlevel_hw_init(struct dwc2_hsotg *hsotg)
 	if (IS_ERR(hsotg->clk))
 		return dev_err_probe(hsotg->dev, PTR_ERR(hsotg->clk), "cannot get otg clock\n");
 
+	hsotg->utmi_clk = devm_clk_get_optional(hsotg->dev, "utmi");
+	if (IS_ERR(hsotg->utmi_clk))
+		return dev_err_probe(hsotg->dev, PTR_ERR(hsotg->utmi_clk),
+				     "cannot get utmi clock\n");
+
 	/* Regulators */
 	for (i = 0; i < ARRAY_SIZE(hsotg->supplies); i++)
 		hsotg->supplies[i].supply = dwc2_hsotg_supply_names[i];
-- 
2.25.1