Date:   Thu, 15 Mar 2018 20:39:58 +0900
From:   Masahiro Yamada <yamada.masahiro@...ionext.com>
To:     Felipe Balbi <felipe.balbi@...ux.intel.com>,
        linux-usb@...r.kernel.org
Cc:     Masami Hiramatsu <mhiramat@...nel.org>,
        Jassi Brar <jaswinder.singh@...aro.org>,
        Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        devicetree@...r.kernel.org, Felipe Balbi <balbi@...nel.org>,
        linux-kernel@...r.kernel.org, Rob Herring <robh+dt@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Mark Rutland <mark.rutland@....com>
Subject: [PATCH 2/2] usb: dwc3: add clock and resets

dwc3-of-simple.c only handles arbitrary number of clocks and resets.
They are both generic enough to be put into the dwc3 core.  For simple
cases, a nested node structure like follows:

  dwc3-glue {
          compatible = "foo,dwc3";
          clocks = ...;
          resets = ...;
          ...

          dwc3 {
                  compatible = "snps,dwc3";
                  ...
          };
  }

would be turned into a single node:

  dwc3 {
          compatible = "foo,dwc3", "snps,dwc3";
          clocks = ...;
          resets = ...;
          ...
  }

I inserted reset_control_deassert() and clk_enable() before the first
register access, i.e. dwc3_cache_hwparams().

Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>
---

 Documentation/devicetree/bindings/usb/dwc3.txt |   2 +
 drivers/usb/dwc3/core.c                        | 127 ++++++++++++++++++++++++-
 drivers/usb/dwc3/core.h                        |   5 +
 3 files changed, 132 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/usb/dwc3.txt b/Documentation/devicetree/bindings/usb/dwc3.txt
index 44e8bab..67e9cfb 100644
--- a/Documentation/devicetree/bindings/usb/dwc3.txt
+++ b/Documentation/devicetree/bindings/usb/dwc3.txt
@@ -9,12 +9,14 @@ Required properties:
  - interrupts: Interrupts used by the dwc3 controller.
 
 Optional properties:
+ - clocks: list of phandle and clock specifier pairs
  - usb-phy : array of phandle for the PHY device.  The first element
    in the array is expected to be a handle to the USB2/HS PHY and
    the second element is expected to be a handle to the USB3/SS PHY
  - phys: from the *Generic PHY* bindings
  - phy-names: from the *Generic PHY* bindings; supported names are "usb2-phy"
 	or "usb3-phy".
+ - resets: list of phandle and reset specifier pairs
  - snps,usb3_lpm_capable: determines if platform is USB3 LPM capable
  - snps,disable_scramble_quirk: true when SW should disable data scrambling.
 	Only really useful for FPGA builds.
diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index e9083a3..f17e4a9 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -8,6 +8,7 @@
  *	    Sebastian Andrzej Siewior <bigeasy@...utronix.de>
  */
 
+#include <linux/clk.h>
 #include <linux/version.h>
 #include <linux/module.h>
 #include <linux/kernel.h>
@@ -24,6 +25,7 @@
 #include <linux/of.h>
 #include <linux/acpi.h>
 #include <linux/pinctrl/consumer.h>
+#include <linux/reset.h>
 
 #include <linux/usb/ch9.h>
 #include <linux/usb/gadget.h>
@@ -240,6 +242,74 @@ static int dwc3_core_soft_reset(struct dwc3 *dwc)
 	return -ETIMEDOUT;
 }
 
+static int dwc3_core_get_clks(struct dwc3 *dwc)
+{
+	struct device *dev = dwc->dev;
+	struct device_node *node = dev->of_node;
+	struct clk *clk;
+	int num_clks, i;
+
+	num_clks = of_count_phandle_with_args(node, "clocks", "#clock-cells");
+	if (num_clks <= 0)
+		return 0;
+
+	dwc->num_clks = num_clks;
+
+	dwc->clks = devm_kcalloc(dev, num_clks, sizeof(*dwc->clks), GFP_KERNEL);
+	if (!dwc->clks)
+		return -ENOMEM;
+
+	for (i = 0; i < num_clks; i++) {
+		clk = of_clk_get(node, i);
+		if (IS_ERR(clk))
+			goto put_clks;
+		dwc->clks[i] = clk;
+	}
+
+	return 0;
+
+put_clks:
+	while (--i >= 0)
+		clk_put(dwc->clks[i]);
+
+	return PTR_ERR(clk);
+}
+
+static void dwc3_core_put_clks(struct dwc3 *dwc)
+{
+	int i;
+
+	for (i = dwc->num_clks - 1; i >= 0; i--)
+		clk_put(dwc->clks[i]);
+}
+
+static int dwc3_core_enable_clks(struct dwc3 *dwc)
+{
+	int ret, i;
+
+	for (i = 0; i < dwc->num_clks; i++) {
+		ret = clk_prepare_enable(dwc->clks[i]);
+		if (ret)
+			goto disable_clks;
+	}
+
+	return 0;
+
+disable_clks:
+	while (--i >= 0)
+		clk_disable_unprepare(dwc->clks[i]);
+
+	return ret;
+}
+
+static void dwc3_core_disable_clks(struct dwc3 *dwc)
+{
+	int i;
+
+	for (i = dwc->num_clks - 1; i >= 0; i--)
+		clk_disable_unprepare(dwc->clks[i]);
+}
+
 /*
  * dwc3_frame_length_adjustment - Adjusts frame length if required
  * @dwc3: Pointer to our controller context structure
@@ -641,6 +711,8 @@ static void dwc3_core_exit(struct dwc3 *dwc)
 	usb_phy_set_suspend(dwc->usb3_phy, 1);
 	phy_power_off(dwc->usb2_generic_phy);
 	phy_power_off(dwc->usb3_generic_phy);
+	dwc3_core_disable_clks(dwc);
+	reset_control_assert(dwc->resets);
 }
 
 static bool dwc3_core_is_valid(struct dwc3 *dwc)
@@ -1205,6 +1277,22 @@ static int dwc3_probe(struct platform_device *pdev)
 
 	dwc3_get_properties(dwc);
 
+	dwc->resets = devm_reset_control_array_get_optional_shared(dev);
+	if (IS_ERR(dwc->resets))
+		return PTR_ERR(dwc->resets);
+
+	ret = dwc3_core_get_clks(dwc);
+	if (ret)
+		return ret;
+
+	ret = reset_control_deassert(dwc->resets);
+	if (ret)
+		goto put_clks;
+
+	ret = dwc3_core_enable_clks(dwc);
+	if (ret)
+		goto assert_resets;
+
 	platform_set_drvdata(pdev, dwc);
 	dwc3_cache_hwparams(dwc);
 
@@ -1268,6 +1356,14 @@ static int dwc3_probe(struct platform_device *pdev)
 	pm_runtime_put_sync(&pdev->dev);
 	pm_runtime_disable(&pdev->dev);
 
+	dwc3_core_disable_clks(dwc);
+
+assert_resets:
+	reset_control_assert(dwc->resets);
+
+put_clks:
+	dwc3_core_put_clks(dwc);
+
 	return ret;
 }
 
@@ -1289,11 +1385,38 @@ static int dwc3_remove(struct platform_device *pdev)
 
 	dwc3_free_event_buffers(dwc);
 	dwc3_free_scratch_buffers(dwc);
+	dwc3_core_put_clks(dwc);
 
 	return 0;
 }
 
 #ifdef CONFIG_PM
+static int dwc3_core_init_for_resume(struct dwc3 *dwc)
+{
+	int ret;
+
+	ret = reset_control_deassert(dwc->resets);
+	if (ret)
+		return ret;
+
+	ret = dwc3_core_enable_clks(dwc);
+	if (ret)
+		goto assert_resets;
+
+	ret = dwc3_core_init(dwc);
+	if (ret)
+		goto disable_clks;
+
+	return 0;
+
+disable_clks:
+	dwc3_core_disable_clks(dwc);
+assert_resets:
+	reset_control_assert(dwc->resets);
+
+	return ret;
+}
+
 static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
 {
 	unsigned long	flags;
@@ -1325,7 +1448,7 @@ static int dwc3_resume_common(struct dwc3 *dwc, pm_message_t msg)
 
 	switch (dwc->current_dr_role) {
 	case DWC3_GCTL_PRTCAP_DEVICE:
-		ret = dwc3_core_init(dwc);
+		ret = dwc3_core_init_for_resume(dwc);
 		if (ret)
 			return ret;
 
@@ -1336,7 +1459,7 @@ static int dwc3_resume_common(struct dwc3 *dwc, pm_message_t msg)
 	case DWC3_GCTL_PRTCAP_HOST:
 		/* nothing to do on host runtime_resume */
 		if (!PMSG_IS_AUTO(msg)) {
-			ret = dwc3_core_init(dwc);
+			ret = dwc3_core_init_for_resume(dwc);
 			if (ret)
 				return ret;
 		}
diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index 860d2bc..14cd335 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -891,6 +891,11 @@ struct dwc3 {
 	struct usb_gadget	gadget;
 	struct usb_gadget_driver *gadget_driver;
 
+	struct clk		**clks;
+	int			num_clks;
+
+	struct reset_control	*resets;
+
 	struct usb_phy		*usb2_phy;
 	struct usb_phy		*usb3_phy;
 
-- 
2.7.4

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