[PATCH v2] phy: rcar-gen3-usb2: add sysfs for usb role swap

[PATCH v2] phy: rcar-gen3-usb2: add sysfs for usb role swap

[Yoshihiro Shimoda]

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.uh@renesas.com>
---
 This patch is based on the latest linux-phy.git / next branch.
 (commit id = 7809cd2ce6abd4f431e4b14e6b1276a7cc842ac4)

 Since this patch is related to usb, I added email addresses of Greg, Felipe,
 Peter and USB ML as CC. (This patch doesn't use USB OTG FSM though.)

 Changed from v1:
  - rebase the latest next branch.

 .../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.uh@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

Re: [PATCH v2] phy: rcar-gen3-usb2: add sysfs for usb role swap

[Peter Chen]

On Tue, Nov 01, 2016 at 04:01:58PM +0900, Yoshihiro Shimoda wrote:
> 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.uh@renesas.com>
> ---
>  This patch is based on the latest linux-phy.git / next branch.
>  (commit id = 7809cd2ce6abd4f431e4b14e6b1276a7cc842ac4)
> 
>  Since this patch is related to usb, I added email addresses of Greg, Felipe,
>  Peter and USB ML as CC. (This patch doesn't use USB OTG FSM though.)
> 
>  Changed from v1:
>   - rebase the latest next branch.
> 
>  .../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.uh@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

Would you really care OTG FSM state machine? If not, you could just use
"host" and "peripheral" to stand for current USB role, and implement
role switch sysfs like: /sys/devices/platform/<phy-name>/role.

Peter

> 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
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-usb" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

-- 

Best Regards,
Peter Chen

RE: [PATCH v2] phy: rcar-gen3-usb2: add sysfs for usb role swap

[Yoshihiro Shimoda]

Hi Peter,

> From: Peter Chen [mailto:hzpeterchen@gmail.com]
> Sent: Tuesday, November 01, 2016 8:38 PM
> 
> On Tue, Nov 01, 2016 at 04:01:58PM +0900, Yoshihiro Shimoda wrote:
> > 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.uh@renesas.com>
> > ---
> >  This patch is based on the latest linux-phy.git / next branch.
> >  (commit id = 7809cd2ce6abd4f431e4b14e6b1276a7cc842ac4)
> >
> >  Since this patch is related to usb, I added email addresses of Greg, Felipe,
> >  Peter and USB ML as CC. (This patch doesn't use USB OTG FSM though.)
> >
> >  Changed from v1:
> >   - rebase the latest next branch.
> >
> >  .../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.uh@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
> 
> Would you really care OTG FSM state machine? If not, you could just use
> "host" and "peripheral" to stand for current USB role, and implement
> role switch sysfs like: /sys/devices/platform/<phy-name>/role.

Thank you for the comment!
Since I would not care OTG FSM state machine for now, I will modify the patch to
use "host" and "peripheral" that you suggested.

Best regards,
Yoshihiro Shimoda

> Peter
> 

RE: [PATCH v2] phy: rcar-gen3-usb2: add sysfs for usb role swap

[Yoshihiro Shimoda]

Hi Peter,

> From: Peter Chen [mailto:hzpeterchen@gmail.com]
> Sent: Tuesday, November 01, 2016 8:38 PM
> 
> On Tue, Nov 01, 2016 at 04:01:58PM +0900, Yoshihiro Shimoda wrote:
> > 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.uh@renesas.com>
> > ---
> >  This patch is based on the latest linux-phy.git / next branch.
> >  (commit id = 7809cd2ce6abd4f431e4b14e6b1276a7cc842ac4)
> >
> >  Since this patch is related to usb, I added email addresses of Greg, Felipe,
> >  Peter and USB ML as CC. (This patch doesn't use USB OTG FSM though.)
> >
> >  Changed from v1:
> >   - rebase the latest next branch.
> >
> >  .../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.uh@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
> 
> Would you really care OTG FSM state machine? If not, you could just use
> "host" and "peripheral" to stand for current USB role, and implement
> role switch sysfs like: /sys/devices/platform/<phy-name>/role.

Thank you for the comment!
Since I would not care OTG FSM state machine for now, I will modify the patch to
use "host" and "peripheral" that you suggested.

Best regards,
Yoshihiro Shimoda

> Peter
>