Re: [PATCH v2] usb: phy: samsung: Add support to set pmu isolation

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Hi Vivek,

On 12/18/2012 02:56 PM, Vivek Gautam wrote:
Adding support to parse device node data in order to get
required properties to set pmu isolation for usb-phy.

Signed-off-by: Vivek Gautam<gautam.vivek@xxxxxxxxxxx>
---

Changes from v1:
  - Changed the name of property for phy handler from'samsung,usb-phyctrl'
    to 'samsung,usb-phyhandle' to make it look more generic.
  - Similarly 'samsung,phyctrl-reg' is changed to 'samsung,phyhandle-reg'
  - Added a check for 'samsung,usb-phyhandle' before getting node from
    phandle.
  - Putting the node using 'of_node_put()' which had been missed.
  - Adding necessary check for the pointer in 'samsung_usbphy_set_isolation()'
    to avoid any NULL pointer dereferencing.
  - Unmapping the register ioremapped in 'samsung_usbphy_parse_dt_param()'.


  .../devicetree/bindings/usb/samsung-usbphy.txt     |   12 +++
  drivers/usb/phy/samsung-usbphy.c                   |   94 ++++++++++++++++++--
  2 files changed, 98 insertions(+), 8 deletions(-)

diff --git a/Documentation/devicetree/bindings/usb/samsung-usbphy.txt b/Documentation/devicetree/bindings/usb/samsung-usbphy.txt
index 7b26e2d..a7b28b2 100644
--- a/Documentation/devicetree/bindings/usb/samsung-usbphy.txt
+++ b/Documentation/devicetree/bindings/usb/samsung-usbphy.txt
@@ -9,3 +9,15 @@ Required properties:
  - compatible : should be "samsung,exynos4210-usbphy"
  - reg : base physical address of the phy registers and length of memory mapped
  	region.
+
+Optional properties:
+- samsung,usb-phyhandle : should point to usb-phyhandle sub-node which provides
+			binding data to enable/disable device PHY handled by
+			PMU register.
+
+			Required properties:
+			- compatible : should be "samsung,usbdev-phyctrl" for
+					DEVICE type phy.
+			- samsung,phyhandle-reg: base physical address of
+						PHY_CONTROL register in PMU.
+- samsung,enable-mask : should be '1'

This should only be 1 for Exynos4210+ SoCs, right ?
S5PV210 uses bit 0 for OTG and bit1 for USB host, doesn't it ? And for s3c64xx
it seems to be bit 16.

How about deriving this information from 'compatible' property instead ?

Maybe you could just encode the USB PMU registers (I assume those aren't
touched by anything but the usb drivers) in a regular 'reg' property in
an usbphy subnode. Then the driver could interpret it also with help
of 'compatible' property. And you could just use of_iomap(). E.g.

 usbphy@12130000 {
 	compatible = "samsung,exynos5250-usbphy";
	reg = <0x12130000 0x100>, <0x12100000 0x100>;
	usbphy-pmu {
		/* USB device and host PHY_CONTROL registers */
		reg = <0x10040704 8>;
	};
 };

Your "samsung,usb-phyhandle" approach seems over-engineered to me.
I might be missing something though.

diff --git a/drivers/usb/phy/samsung-usbphy.c b/drivers/usb/phy/samsung-usbphy.c
index 5c5e1bb5..4ceabe3 100644
--- a/drivers/usb/phy/samsung-usbphy.c
+++ b/drivers/usb/phy/samsung-usbphy.c
@@ -72,6 +72,8 @@ enum samsung_cpu_type {
   * @dev: The parent device supplied to the probe function
   * @clk: usb phy clock
   * @regs: usb phy register memory base
+ * @devctrl_reg: usb device phy-control pmu register memory base

hum, this name is not really helpful in understanding what's going
on here.

Looking at arch/arm/mach-s5pv210/setup-usb-phy.c, there is only one
PHY_CONTROL (Power Management Unit) register for both OTG and USB host
PHYs. So are you really taking care of that case as well ?

+ * @en_mask: enable mask
   * @ref_clk_freq: reference clock frequency selection
   * @cpu_type: machine identifier
   */
@@ -81,12 +83,73 @@ struct samsung_usbphy {
  	struct device	*dev;
  	struct clk	*clk;
  	void __iomem	*regs;
+	void __iomem	*devctrl_reg;
+	u32		en_mask;
  	int		ref_clk_freq;
  	int		cpu_type;
  };

  #define phy_to_sphy(x)		container_of((x), struct samsung_usbphy, phy)

+static int samsung_usbphy_parse_dt_param(struct samsung_usbphy *sphy)
+{
+	struct device_node *usb_phyctrl;
+	u32 reg;
+	int lenp;
+
+	if (!sphy->dev->of_node) {
+		sphy->devctrl_reg = NULL;
+		return -ENODEV;
+	}
+
+	if (of_get_property(sphy->dev->of_node, "samsung,usb-phyhandle",&lenp)) {
+		usb_phyctrl = of_parse_phandle(sphy->dev->of_node,
+						"samsung,usb-phyhandle", 0);
+		if (!usb_phyctrl) {
+			dev_warn(sphy->dev, "Can't get usb-phy handle\n");
+			sphy->devctrl_reg = NULL;
+		}
+
+		of_property_read_u32(usb_phyctrl, "samsung,phyhandle-reg",&reg);
+
+		sphy->devctrl_reg = ioremap(reg, SZ_4);

What happens if invalid address value is assigned to 'samsung,phyhandle-reg' ?

+		of_property_read_u32(sphy->dev->of_node, "samsung,enable-mask",
+							&sphy->en_mask);
+		of_node_put(usb_phyctrl);
+	} else {
+		dev_warn(sphy->dev, "Can't get usb-phy handle\n");
+		sphy->devctrl_reg = NULL;
+	}
+
+	return 0;
+}
+
+/*
+ * Set isolation here for phy.
+ * SOCs control this by controlling corresponding PMU registers
+ */
+static void samsung_usbphy_set_isolation(struct samsung_usbphy *sphy, int on)
+{
+	void __iomem *usb_phyctrl_reg;
+	u32 en_mask = sphy->en_mask;
+	u32 reg;
+
+	usb_phyctrl_reg = sphy->devctrl_reg;
+
+	if (!usb_phyctrl_reg) {
+		dev_warn(sphy->dev, "Can't set pmu isolation\n");
+		return;
+	}
+
+	reg = readl(usb_phyctrl_reg);
+
+	if (on)
+		writel(reg&  ~en_mask, usb_phyctrl_reg);
+	else
+		writel(reg | en_mask, usb_phyctrl_reg);
+}
+
  /*
   * Returns reference clock frequency selection value
   */
@@ -199,6 +262,8 @@ static int samsung_usbphy_init(struct usb_phy *phy)
  	/* Disable phy isolation */
  	if (sphy->plat&&  sphy->plat->pmu_isolation)
  		sphy->plat->pmu_isolation(false);
+	else
+		samsung_usbphy_set_isolation(sphy, false);

  	/* Initialize usb phy registers */
  	samsung_usbphy_enable(sphy);
@@ -228,6 +293,8 @@ static void samsung_usbphy_shutdown(struct usb_phy *phy)
  	/* Enable phy isolation */
  	if (sphy->plat&&  sphy->plat->pmu_isolation)
  		sphy->plat->pmu_isolation(true);
+	else
+		samsung_usbphy_set_isolation(sphy, true);

  	clk_disable_unprepare(sphy->clk);
  }
@@ -249,17 +316,12 @@ static inline int samsung_usbphy_get_driver_data(struct platform_device *pdev)
  static int __devinit samsung_usbphy_probe(struct platform_device *pdev)
  {
  	struct samsung_usbphy *sphy;
-	struct samsung_usbphy_data *pdata;
+	struct samsung_usbphy_data *pdata = pdev->dev.platform_data;
  	struct device *dev =&pdev->dev;
  	struct resource *phy_mem;
  	void __iomem	*phy_base;
  	struct clk *clk;
-
-	pdata = pdev->dev.platform_data;
-	if (!pdata) {
-		dev_err(&pdev->dev, "%s: no platform data defined\n", __func__);
-		return -EINVAL;
-	}
+	int ret;

  	phy_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	if (!phy_mem) {
@@ -283,7 +345,20 @@ static int __devinit samsung_usbphy_probe(struct platform_device *pdev)
  		return PTR_ERR(clk);
  	}

-	sphy->dev		=&pdev->dev;
+	sphy->dev =&pdev->dev;

	sphy->dev = dev;

+
+	ret = samsung_usbphy_parse_dt_param(sphy);
+	if (ret) {
+		/* fallback to pdata */
+		if (!pdata) {
+			dev_err(&pdev->dev,
+				"%s: no device data found\n", __func__);

I find term "device data" a bit confusing here.

+			return -ENODEV;

In the original code -EINVAL was returned when platform_data was not set.

+		} else {
+			sphy->plat = pdata;
+		}
+	}
+

How about rewriting this to:

	if (dev->of_node) {
		ret = samsung_usbphy_parse_dt_param(sphy);
		if (ret < 0)
			return ret;
	} else {
		if (!pdata) {
			dev_err(dev, "no platform data specified\n");
			return -EINVAL;
		}
	}	

This way we won't be obfuscating any error code returned from the
OF parsing function.

  	sphy->plat		= pdata;
  	sphy->regs		= phy_base;
  	sphy->clk		= clk;
@@ -305,6 +380,9 @@ static int __exit samsung_usbphy_remove(struct platform_device *pdev)

  	usb_remove_phy(&sphy->phy);

+	if (sphy->devctrl_reg)
+		iounmap(sphy->devctrl_reg);
+
  	return 0;
  }

--

Regards,
Sylwester
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