This patch adds sysfs "otg_inputs" for usb role swap. This parameter
is write-only and if you use them 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 (as host), you input the following command:
   # echo a_bus_req/ > /sys/devices/platform/soc/ee080200.usb-phy/otg_inputs
 3) On B-device (as peripheral), you input the following command:
   # echo b_bus_req > /sys/devices/platform/soc/ee080200.usb-phy/otg_inputs

Then, the A-device acts as a peripheral (A-peripheral) and the B-device
acts as a host (B-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 condition keeps "A-peripheral".)
 # echo a_bus_drop > /sys/devices/platform/soc/ee080200.usb-phy/otg_inputs

Also you can use the following command if you want the B-device board to
act as a peripheral again.
 # echo b_bus_req/ > /sys/devices/platform/soc/ee080200.usb-phy/otg_inputs

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda...@renesas.com>
---
 This patch is based on the linux-phy.git / phy-for-4.9-resolved_v3 tag.
 (commit id = c4b0bf82f705747ed7de90c5736b07248cbb29cd)

 .../ABI/testing/sysfs-platform-phy-rcar-gen3-usb2  |  11 ++
 drivers/phy/phy-rcar-gen3-usb2.c                   | 124 ++++++++++++++++++++-
 2 files changed, 134 insertions(+), 1 deletion(-)
 create mode 100644 Documentation/ABI/testing/sysfs-platform-phy-rcar-gen3-usb2

diff --git a/Documentation/ABI/testing/sysfs-platform-phy-rcar-gen3-usb2 
b/Documentation/ABI/testing/sysfs-platform-phy-rcar-gen3-usb2
new file mode 100644
index 0000000..c7e715af
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-platform-phy-rcar-gen3-usb2
@@ -0,0 +1,11 @@
+What:          /sys/devices/platform/<phy-name>/otg-inputs
+Date:          October 2016
+KernelVersion: 4.10
+Contact:       Yoshihiro Shimoda <yoshihiro.shimoda...@renesas.com>
+Description:
+               This write-only file changes the phy mode for role swap of usb.
+               This file accepts the following strings:
+                "a_bus_req/" - switching from A-Host to A-Peripheral
+                "a_bus_drop" - switching from A-Peripheral to A-Host
+                "b_bus_req"  - switching from B-Peripheral to B-Host
+                "b_bus_req/" - switching from B-Host to B-Peripheral
diff --git a/drivers/phy/phy-rcar-gen3-usb2.c b/drivers/phy/phy-rcar-gen3-usb2.c
index 3d97ead..80f5bcc 100644
--- a/drivers/phy/phy-rcar-gen3-usb2.c
+++ b/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 +212,71 @@ static void rcar_gen3_device_recognition(struct 
rcar_gen3_chan *ch)
                rcar_gen3_init_for_peri(ch);
 }
 
+/*
+ * The following table is a state transition for usb phy mode:
+ * State                       Event   Next state
+ * disconnected:               E1      a_host
+ *                             E2      b_peripheral
+ * A-Device - a_host:          E2      b_peripheral
+ *                             E3      disconnected
+ *                             E4      a_suspend
+ * A-Device - a_suspend:       E2      b_peripheral
+ *                             E3      disconnected
+ *                             E5      a_host
+ *                             E6      a_peripheral
+ * A-Device - a_peripheral:    E2      b_peripheral
+ *                             E3      disconnected
+ *                             E5      a_host
+ * B-Device - b_peripheral:    E3      disconnected
+ *                             E7      b_wait_acon
+ * B-Device - b_wait_acon      E3      disconnected
+ *                             E8      b_host
+ * B-Device - b_host:          E3      disconnected
+ *                             E9      b_peripheral
+ * Events:
+ * E1: ID = 0 && Host detects D+ pull up,      E2: ID = 1 && VBUS = 1
+ * E3: VBUS = 0 || ID is changed,              E4: a_bus_req/
+ * E5: a_bus_drop,                             E6: Turns D+ pull up off
+ * E7: b_bus_req,                              E8: Detects D+ pull up
+ * E9: b_bus_req/
+ */
+static ssize_t otg_inputs_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_host, is_b_device;
+
+       if (!ch->has_otg || !ch->phy->init_count)
+               return -EIO;
+
+       is_b_device = rcar_gen3_check_id(ch);   /* true = B-Device */
+       is_host = !(readl(ch->base + USB2_COMMCTRL) & USB2_COMMCTRL_OTG_PERI);
+
+       if (!strncmp(buf, "a_bus_req/", strlen("a_bus_req/"))) {
+               if (is_b_device)                /* fail if B-device */
+                       return -ENODEV;
+               rcar_gen3_init_for_a_peri(ch);
+       } else if (!strncmp(buf, "a_bus_drop", strlen("a_bus_drop"))) {
+               if (is_b_device || is_host)     /* fail if B-device or A-host */
+                       return -ENODEV;
+               rcar_gen3_init_from_a_peri_to_a_host(ch);
+       } else if (!strncmp(buf, "b_bus_req/", strlen("b_bus_req/"))) {
+               if (!is_b_device || !is_host)   /* fail if A-device or B-peri */
+                       return -ENODEV;
+               rcar_gen3_init_for_peri(ch);
+       } else if (!strncmp(buf, "b_bus_req", strlen("b_bus_req"))) {
+               if (!is_b_device)               /* fail if A-device */
+                       return -ENODEV;
+               rcar_gen3_init_for_b_host(ch);
+       } else {
+               return -EINVAL;
+       }
+
+       return count;
+}
+static DEVICE_ATTR_WO(otg_inputs);
+
 static void rcar_gen3_init_otg(struct rcar_gen3_chan *ch)
 {
        void __iomem *usb2_base = ch->base;
@@ -351,21 +454,40 @@ 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_otg_inputs);
+               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_otg_inputs);
+
+       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);
 
-- 
1.9.1

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