phy: rcar-gen3-usb2: add sysfs for usb role swap

This patch adds sysfs "role" for usb role swap. This parameter can be
read and write. If you use this file as the following, you can swap
the usb role.

For example:
 1) Connect a usb cable using 2 Salvator-x boards
 2) On A-Device (ID pin is low), you input the following command:
   # echo peripheral > /sys/devices/platform/soc/ee080200.usb-phy/role
 3) On B-Device (ID pin is high), you input the following command:
   # echo host > /sys/devices/platform/soc/ee080200.usb-phy/role

Then, the A-device acts as a peripheral and the B-device acts as a host.
Please note that A-Device must input the following command if you
want the board to act as a host again. (even if you disconnect the usb
cable, since id state may be the same, the A-Device keeps to act as
peripheral.)
 # echo host > /sys/devices/platform/soc/ee080200.usb-phy/role
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Reviewed-by: Peter Chen <peter.chen@nxp.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>

Documentation/ABI/testing/sysfs-platform-phy-rcar-gen3-usb2

+What:		/sys/devices/platform/<phy-name>/role
+Date:		October 2016
+KernelVersion:	4.10
+Contact:	Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
+Description:
+		This file can be read and write.
+		The file can show/change the phy mode for role swap of usb.
+
+		Write the following strings to change the mode:
+		 "host" - switching mode from peripheral to host.
+		 "peripheral" - switching mode from host to peripheral.
+
+		Read the file, then it shows the following strings:
+		 "host" - The mode is host now.
+		 "peripheral" - The mode is peripheral now.

drivers/phy/phy-rcar-gen3-usb2.c

@@ -70,6 +70,7 @@
 #define USB2_LINECTRL1_DP_RPD		BIT(18)
 #define USB2_LINECTRL1_DMRPD_EN		BIT(17)
 #define USB2_LINECTRL1_DM_RPD		BIT(16)
+#define USB2_LINECTRL1_OPMODE_NODRV	BIT(6)
 
 /* ADPCTRL */
 #define USB2_ADPCTRL_OTGSESSVLD		BIT(20)
@@ -161,6 +162,43 @@ static void rcar_gen3_init_for_peri(struct rcar_gen3_chan *ch)
 	schedule_work(&ch->work);
 }
 
+static void rcar_gen3_init_for_b_host(struct rcar_gen3_chan *ch)
+{
+	void __iomem *usb2_base = ch->base;
+	u32 val;
+
+	val = readl(usb2_base + USB2_LINECTRL1);
+	writel(val | USB2_LINECTRL1_OPMODE_NODRV, usb2_base + USB2_LINECTRL1);
+
+	rcar_gen3_set_linectrl(ch, 1, 1);
+	rcar_gen3_set_host_mode(ch, 1);
+	rcar_gen3_enable_vbus_ctrl(ch, 0);
+
+	val = readl(usb2_base + USB2_LINECTRL1);
+	writel(val & ~USB2_LINECTRL1_OPMODE_NODRV, usb2_base + USB2_LINECTRL1);
+}
+
+static void rcar_gen3_init_for_a_peri(struct rcar_gen3_chan *ch)
+{
+	rcar_gen3_set_linectrl(ch, 0, 1);
+	rcar_gen3_set_host_mode(ch, 0);
+	rcar_gen3_enable_vbus_ctrl(ch, 1);
+}
+
+static void rcar_gen3_init_from_a_peri_to_a_host(struct rcar_gen3_chan *ch)
+{
+	void __iomem *usb2_base = ch->base;
+	u32 val;
+
+	val = readl(usb2_base + USB2_OBINTEN);
+	writel(val & ~USB2_OBINT_BITS, usb2_base + USB2_OBINTEN);
+
+	rcar_gen3_enable_vbus_ctrl(ch, 0);
+	rcar_gen3_init_for_host(ch);
+
+	writel(val | USB2_OBINT_BITS, usb2_base + USB2_OBINTEN);
+}
+
 static bool rcar_gen3_check_id(struct rcar_gen3_chan *ch)
 {
 	return !!(readl(ch->base + USB2_ADPCTRL) & USB2_ADPCTRL_IDDIG);
@@ -174,6 +212,65 @@ static void rcar_gen3_device_recognition(struct rcar_gen3_chan *ch)
 		rcar_gen3_init_for_peri(ch);
 }
 
+static bool rcar_gen3_is_host(struct rcar_gen3_chan *ch)
+{
+	return !(readl(ch->base + USB2_COMMCTRL) & USB2_COMMCTRL_OTG_PERI);
+}
+
+static ssize_t role_store(struct device *dev, struct device_attribute *attr,
+			  const char *buf, size_t count)
+{
+	struct rcar_gen3_chan *ch = dev_get_drvdata(dev);
+	bool is_b_device, is_host, new_mode_is_host;
+
+	if (!ch->has_otg || !ch->phy->init_count)
+		return -EIO;
+
+	/*
+	 * is_b_device: true is B-Device. false is A-Device.
+	 * If {new_mode_}is_host: true is Host mode. false is Peripheral mode.
+	 */
+	is_b_device = rcar_gen3_check_id(ch);
+	is_host = rcar_gen3_is_host(ch);
+	if (!strncmp(buf, "host", strlen("host")))
+		new_mode_is_host = true;
+	else if (!strncmp(buf, "peripheral", strlen("peripheral")))
+		new_mode_is_host = false;
+	else
+		return -EINVAL;
+
+	/* If current and new mode is the same, this returns the error */
+	if (is_host == new_mode_is_host)
+		return -EINVAL;
+
+	if (new_mode_is_host) {		/* And is_host must be false */
+		if (!is_b_device)	/* A-Peripheral */
+			rcar_gen3_init_from_a_peri_to_a_host(ch);
+		else			/* B-Peripheral */
+			rcar_gen3_init_for_b_host(ch);
+	} else {			/* And is_host must be true */
+		if (!is_b_device)	/* A-Host */
+			rcar_gen3_init_for_a_peri(ch);
+		else			/* B-Host */
+			rcar_gen3_init_for_peri(ch);
+	}
+
+	return count;
+}
+
+static ssize_t role_show(struct device *dev, struct device_attribute *attr,
+			 char *buf)
+{
+	struct rcar_gen3_chan *ch = dev_get_drvdata(dev);
+
+	if (!ch->has_otg || !ch->phy->init_count)
+		return -EIO;
+
+	return sprintf(buf, "%s\n", rcar_gen3_is_host(ch) ? "host" :
+							    "peripheral");
+}
+static DEVICE_ATTR_RW(role);
+
 static void rcar_gen3_init_otg(struct rcar_gen3_chan *ch)
 {
 	void __iomem *usb2_base = ch->base;
@@ -351,21 +448,40 @@ static int rcar_gen3_phy_usb2_probe(struct platform_device *pdev)
 		channel->vbus = NULL;
 	}
 
+	platform_set_drvdata(pdev, channel);
 	phy_set_drvdata(channel->phy, channel);
 
 	provider = devm_of_phy_provider_register(dev, of_phy_simple_xlate);
-	if (IS_ERR(provider))
+	if (IS_ERR(provider)) {
 		dev_err(dev, "Failed to register PHY provider\n");
+	} else if (channel->has_otg) {
+		int ret;
+
+		ret = device_create_file(dev, &dev_attr_role);
+		if (ret < 0)
+			return ret;
+	}
 
 	return PTR_ERR_OR_ZERO(provider);
 }
 
+static int rcar_gen3_phy_usb2_remove(struct platform_device *pdev)
+{
+	struct rcar_gen3_chan *channel = platform_get_drvdata(pdev);
+
+	if (channel->has_otg)
+		device_remove_file(&pdev->dev, &dev_attr_role);
+
+	return 0;
+};
+
 static struct platform_driver rcar_gen3_phy_usb2_driver = {
 	.driver = {
 		.name		= "phy_rcar_gen3_usb2",
 		.of_match_table	= rcar_gen3_phy_usb2_match_table,
 	},
 	.probe	= rcar_gen3_phy_usb2_probe,
+	.remove = rcar_gen3_phy_usb2_remove,
 };
 module_platform_driver(rcar_gen3_phy_usb2_driver);