Patchwork [v3,4/4] USB: OMAP1: Tahvo USB transceiver driver

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Submitter Aaro Koskinen
Date June 18, 2013, 5:07 p.m.
Message ID <1371575221-360-5-git-send-email-aaro.koskinen@iki.fi>
Download mbox | patch
Permalink /patch/252396/
State New
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Comments

Aaro Koskinen - June 18, 2013, 5:07 p.m.
Add Tahvo USB transceiver driver.

Based on old code from linux-omap tree. The original driver was written
by Juha Yrjölä, Tony Lindgren, and Timo Teräs.

Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
---
 drivers/usb/phy/Kconfig     |  14 ++
 drivers/usb/phy/Makefile    |   1 +
 drivers/usb/phy/phy-tahvo.c | 448 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 463 insertions(+)
 create mode 100644 drivers/usb/phy/phy-tahvo.c
Felipe Balbi - July 8, 2013, 7:21 a.m.
Hi,

On Tue, Jun 18, 2013 at 08:07:01PM +0300, Aaro Koskinen wrote:
> +static ssize_t vbus_state_show(struct device *device,
> +			       struct device_attribute *attr, char *buf)
> +{
> +	struct tahvo_usb *tu = dev_get_drvdata(device);
> +	return sprintf(buf, "%d\n", tu->vbus_state);
> +}
> +static DEVICE_ATTR(vbus_state, 0444, vbus_state_show, NULL);

VBUS status sounds generic enough, also, you should be printing on/off
here instead of tahvo-specific values. Some users might not have access
to the docs, or even the kernel sources, to understand what that integer
means.

> +static void tahvo_usb_become_host(struct tahvo_usb *tu)
> +{
> +	struct retu_dev *rdev = dev_get_drvdata(tu->pt_dev->dev.parent);
> +
> +	extcon_set_cable_state(&tu->extcon, "USB-HOST", true);
> +
> +	/* Power up the transceiver in USB host mode */
> +	retu_write(rdev, TAHVO_REG_USBR, USBR_REGOUT | USBR_NSUSPEND |
> +		   USBR_MASTER_SW2 | USBR_MASTER_SW1);
> +	tu->phy.state = OTG_STATE_A_IDLE;
> +
> +	check_vbus_state(tu);
> +}
> +
> +static void tahvo_usb_stop_host(struct tahvo_usb *tu)
> +{
> +	tu->phy.state = OTG_STATE_A_IDLE;

shouldn't you undo tahvo_usb_become_host() here ? I mean, set the
transceiver to SLAVE ?

> +static int tahvo_usb_set_host(struct usb_otg *otg, struct usb_bus *host)
> +{
> +	struct tahvo_usb *tu = container_of(otg->phy, struct tahvo_usb, phy);
> +
> +	dev_dbg(&tu->pt_dev->dev, "%s %p\n", __func__, host);
> +
> +	if (otg == NULL)
> +		return -ENODEV;
> +
> +	mutex_lock(&tu->serialize);
> +
> +	if (host == NULL) {
> +		if (tu->tahvo_mode == TAHVO_MODE_HOST)
> +			tahvo_usb_power_off(tu);
> +		otg->host = NULL;
> +		mutex_unlock(&tu->serialize);
> +		return 0;
> +	}
> +
> +	if (tu->tahvo_mode == TAHVO_MODE_HOST) {
> +		otg->host = NULL;
> +		tahvo_usb_become_host(tu);
> +	}
> +
> +	otg->host = host;
> +
> +	mutex_unlock(&tu->serialize);
> +
> +	return 0;
> +}
> +
> +static int tahvo_usb_set_peripheral(struct usb_otg *otg,
> +				    struct usb_gadget *gadget)

I want to get rid of the extra 'gadget' and 'host' parameters on
->set_host() and ->set_peripheral(). Nobody really uses them other than:

my_phy->phy.otg->{gadget,host} = {gadget,host};

For that, I need all other PHYs to stop relying on those parameters and
I'll cook patches for that for v3.12 merge window.

> +static ssize_t otg_mode_store(struct device *device,
> +			      struct device_attribute *attr,
> +			      const char *buf, size_t count)
> +{
> +	struct tahvo_usb *tu = dev_get_drvdata(device);
> +	int r;
> +
> +	mutex_lock(&tu->serialize);
> +	if (count >= 4 && strncmp(buf, "host", 4) == 0) {
> +		if (tu->tahvo_mode == TAHVO_MODE_PERIPHERAL)
> +			tahvo_usb_stop_peripheral(tu);
> +		tu->tahvo_mode = TAHVO_MODE_HOST;
> +		if (tu->phy.otg->host) {
> +			dev_info(device, "HOST mode: host controller present\n");
> +			tahvo_usb_become_host(tu);
> +		} else {
> +			dev_info(device, "HOST mode: no host controller, powering off\n");
> +			tahvo_usb_power_off(tu);
> +		}
> +		r = strlen(buf);
> +	} else if (count >= 10 && strncmp(buf, "peripheral", 10) == 0) {
> +		if (tu->tahvo_mode == TAHVO_MODE_HOST)
> +			tahvo_usb_stop_host(tu);
> +		tu->tahvo_mode = TAHVO_MODE_PERIPHERAL;
> +		if (tu->phy.otg->gadget) {
> +			dev_info(device, "PERIPHERAL mode: gadget driver present\n");
> +			tahvo_usb_become_peripheral(tu);
> +		} else {
> +			dev_info(device, "PERIPHERAL mode: no gadget driver, powering off\n");
> +			tahvo_usb_power_off(tu);
> +		}
> +		r = strlen(buf);
> +	} else {
> +		r = -EINVAL;
> +	}
> +	mutex_unlock(&tu->serialize);
> +
> +	return r;
> +}
> +
> +static DEVICE_ATTR(otg_mode, 0644, otg_mode_show, otg_mode_store);

this looks like something which would be very nice if implemented
generically. Since you, anyway miss the documentation in
Documentation/ABI/ and need to respin the patch, how about making this
generic ?

> +static int tahvo_usb_probe(struct platform_device *pdev)
> +{
> +	struct retu_dev *rdev = dev_get_drvdata(pdev->dev.parent);
> +	struct tahvo_usb *tu;
> +	int ret;
> +
> +	tu = devm_kzalloc(&pdev->dev, sizeof(*tu), GFP_KERNEL);
> +	if (!tu)
> +		return -ENOMEM;
> +
> +	tu->phy.otg = devm_kzalloc(&pdev->dev, sizeof(*tu->phy.otg),
> +				   GFP_KERNEL);
> +	if (!tu->phy.otg)
> +		return -ENOMEM;
> +
> +	tu->pt_dev = pdev;
> +
> +	/* Default mode */
> +#ifdef CONFIG_TAHVO_USB_HOST_BY_DEFAULT
> +	tu->tahvo_mode = TAHVO_MODE_HOST;
> +#else
> +	tu->tahvo_mode = TAHVO_MODE_PERIPHERAL;
> +#endif

should you call become_host()/become_peripheral() here ?

> +	mutex_init(&tu->serialize);
> +
> +	tu->ick = devm_clk_get(&pdev->dev, "usb_l4_ick");
> +	if (!IS_ERR(tu->ick))
> +		clk_enable(tu->ick);
> +
> +	/*
> +	 * Set initial state, so that we generate kevents only on state changes.
> +	 */
> +	tu->vbus_state = retu_read(rdev, TAHVO_REG_IDSR) & TAHVO_STAT_VBUS;
> +
> +	tu->extcon.name = DRIVER_NAME;
> +	tu->extcon.supported_cable = tahvo_cable;
> +	ret = extcon_dev_register(&tu->extcon, &pdev->dev);
> +	if (ret) {
> +		dev_err(&pdev->dev, "could not register extcon device: %d\n",
> +			ret);
> +		return ret;
> +	}
> +
> +	/* Set the initial cable state. */
> +	extcon_set_cable_state(&tu->extcon, "USB-HOST",
> +			       tu->tahvo_mode == TAHVO_MODE_HOST);
> +	extcon_set_cable_state(&tu->extcon, "USB", tu->vbus_state);
> +
> +	tu->irq = platform_get_irq(pdev, 0);
> +	ret = request_threaded_irq(tu->irq, NULL, tahvo_usb_vbus_interrupt, 0,
> +				   "tahvo-vbus", tu);

since your hardirq handler is NULL, you *must* pass IRQF_ONESHOT. /Could
also use devm_request_threaded_irq()

> +	if (ret) {
> +		dev_err(&pdev->dev, "could not register tahvo-vbus irq: %d\n",
> +			ret);
> +		goto err_disable_clk;
> +	}
> +
> +	/* Attributes */
> +	ret = device_create_file(&pdev->dev, &dev_attr_vbus_state);
> +	ret |= device_create_file(&pdev->dev, &dev_attr_otg_mode);

heh, Greg wrote a very interesting article recently (look at his blog)
discussing kernel/userland races wrt creation of sysfs files.

> +	/* Create OTG interface */
> +	tahvo_usb_power_off(tu);
> +	tu->phy.dev = &pdev->dev;
> +	tu->phy.state = OTG_STATE_UNDEFINED;
> +	tu->phy.label = DRIVER_NAME;
> +	tu->phy.set_suspend = tahvo_usb_set_suspend;
> +
> +	tu->phy.otg->phy = &tu->phy;
> +	tu->phy.otg->set_host = tahvo_usb_set_host;
> +	tu->phy.otg->set_peripheral = tahvo_usb_set_peripheral;
> +
> +	ret = usb_add_phy(&tu->phy, USB_PHY_TYPE_USB2);
> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "cannot register USB transceiver: %d\n",
> +			ret);
> +		goto err_free_irq;
> +	}
> +
> +	dev_set_drvdata(&pdev->dev, tu);

what if someone accesses the sysfs file you've already created before
you call dev_set_drvdata? (not sure  if it's possible).
Aaro Koskinen - July 8, 2013, 7:44 p.m.
Hi,

On Mon, Jul 08, 2013 at 10:21:09AM +0300, Felipe Balbi wrote:
> On Tue, Jun 18, 2013 at 08:07:01PM +0300, Aaro Koskinen wrote:
> > +static ssize_t vbus_state_show(struct device *device,
> > +			       struct device_attribute *attr, char *buf)
> > +{
> > +	struct tahvo_usb *tu = dev_get_drvdata(device);
> > +	return sprintf(buf, "%d\n", tu->vbus_state);
> > +}
> > +static DEVICE_ATTR(vbus_state, 0444, vbus_state_show, NULL);
> 
> VBUS status sounds generic enough, also, you should be printing on/off
> here instead of tahvo-specific values. Some users might not have access
> to the docs, or even the kernel sources, to understand what that integer
> means.

Ok, I'll fix.

> > +static void tahvo_usb_become_host(struct tahvo_usb *tu)
> > +{
> > +	struct retu_dev *rdev = dev_get_drvdata(tu->pt_dev->dev.parent);
> > +
> > +	extcon_set_cable_state(&tu->extcon, "USB-HOST", true);
> > +
> > +	/* Power up the transceiver in USB host mode */
> > +	retu_write(rdev, TAHVO_REG_USBR, USBR_REGOUT | USBR_NSUSPEND |
> > +		   USBR_MASTER_SW2 | USBR_MASTER_SW1);
> > +	tu->phy.state = OTG_STATE_A_IDLE;
> > +
> > +	check_vbus_state(tu);
> > +}
> > +
> > +static void tahvo_usb_stop_host(struct tahvo_usb *tu)
> > +{
> > +	tu->phy.state = OTG_STATE_A_IDLE;
> 
> shouldn't you undo tahvo_usb_become_host() here ? I mean, set the
> transceiver to SLAVE ?

tahvo_usb_become_peripheral() (or power_off) is always called after this
function. Actually, these stop functions can be eliminated altogether
as they are only called from a single place...

> > +static int tahvo_usb_set_host(struct usb_otg *otg, struct usb_bus *host)
> > +{
> > +	struct tahvo_usb *tu = container_of(otg->phy, struct tahvo_usb, phy);
> > +
> > +	dev_dbg(&tu->pt_dev->dev, "%s %p\n", __func__, host);
> > +
> > +	if (otg == NULL)
> > +		return -ENODEV;
> > +
> > +	mutex_lock(&tu->serialize);
> > +
> > +	if (host == NULL) {
> > +		if (tu->tahvo_mode == TAHVO_MODE_HOST)
> > +			tahvo_usb_power_off(tu);
> > +		otg->host = NULL;
> > +		mutex_unlock(&tu->serialize);
> > +		return 0;
> > +	}
> > +
> > +	if (tu->tahvo_mode == TAHVO_MODE_HOST) {
> > +		otg->host = NULL;
> > +		tahvo_usb_become_host(tu);
> > +	}
> > +
> > +	otg->host = host;
> > +
> > +	mutex_unlock(&tu->serialize);
> > +
> > +	return 0;
> > +}
> > +
> > +static int tahvo_usb_set_peripheral(struct usb_otg *otg,
> > +				    struct usb_gadget *gadget)
> 
> I want to get rid of the extra 'gadget' and 'host' parameters on
> ->set_host() and ->set_peripheral(). Nobody really uses them other than:
> 
> my_phy->phy.otg->{gadget,host} = {gadget,host};
> 
> For that, I need all other PHYs to stop relying on those parameters and
> I'll cook patches for that for v3.12 merge window.

How will the PHY know if there is a host/gadget driver present? I guess
I will need to wait for those patches...

> > +static ssize_t otg_mode_store(struct device *device,
> > +			      struct device_attribute *attr,
> > +			      const char *buf, size_t count)
> > +{
> > +	struct tahvo_usb *tu = dev_get_drvdata(device);
> > +	int r;
> > +
> > +	mutex_lock(&tu->serialize);
> > +	if (count >= 4 && strncmp(buf, "host", 4) == 0) {
> > +		if (tu->tahvo_mode == TAHVO_MODE_PERIPHERAL)
> > +			tahvo_usb_stop_peripheral(tu);
> > +		tu->tahvo_mode = TAHVO_MODE_HOST;
> > +		if (tu->phy.otg->host) {
> > +			dev_info(device, "HOST mode: host controller present\n");
> > +			tahvo_usb_become_host(tu);
> > +		} else {
> > +			dev_info(device, "HOST mode: no host controller, powering off\n");
> > +			tahvo_usb_power_off(tu);
> > +		}
> > +		r = strlen(buf);
> > +	} else if (count >= 10 && strncmp(buf, "peripheral", 10) == 0) {
> > +		if (tu->tahvo_mode == TAHVO_MODE_HOST)
> > +			tahvo_usb_stop_host(tu);
> > +		tu->tahvo_mode = TAHVO_MODE_PERIPHERAL;
> > +		if (tu->phy.otg->gadget) {
> > +			dev_info(device, "PERIPHERAL mode: gadget driver present\n");
> > +			tahvo_usb_become_peripheral(tu);
> > +		} else {
> > +			dev_info(device, "PERIPHERAL mode: no gadget driver, powering off\n");
> > +			tahvo_usb_power_off(tu);
> > +		}
> > +		r = strlen(buf);
> > +	} else {
> > +		r = -EINVAL;
> > +	}
> > +	mutex_unlock(&tu->serialize);
> > +
> > +	return r;
> > +}
> > +
> > +static DEVICE_ATTR(otg_mode, 0644, otg_mode_show, otg_mode_store);
> 
> this looks like something which would be very nice if implemented
> generically. Since you, anyway miss the documentation in
> Documentation/ABI/ and need to respin the patch, how about making this
> generic ?

Ok, I'll try to come up with something...

> > +static int tahvo_usb_probe(struct platform_device *pdev)
> > +{
> > +	struct retu_dev *rdev = dev_get_drvdata(pdev->dev.parent);
> > +	struct tahvo_usb *tu;
> > +	int ret;
> > +
> > +	tu = devm_kzalloc(&pdev->dev, sizeof(*tu), GFP_KERNEL);
> > +	if (!tu)
> > +		return -ENOMEM;
> > +
> > +	tu->phy.otg = devm_kzalloc(&pdev->dev, sizeof(*tu->phy.otg),
> > +				   GFP_KERNEL);
> > +	if (!tu->phy.otg)
> > +		return -ENOMEM;
> > +
> > +	tu->pt_dev = pdev;
> > +
> > +	/* Default mode */
> > +#ifdef CONFIG_TAHVO_USB_HOST_BY_DEFAULT
> > +	tu->tahvo_mode = TAHVO_MODE_HOST;
> > +#else
> > +	tu->tahvo_mode = TAHVO_MODE_PERIPHERAL;
> > +#endif
> 
> should you call become_host()/become_peripheral() here ?

Not needed. Once the PHY is registered, the framework will call set_host /
set_peripheral and the HW gets set to correct state.

> > +	mutex_init(&tu->serialize);
> > +
> > +	tu->ick = devm_clk_get(&pdev->dev, "usb_l4_ick");
> > +	if (!IS_ERR(tu->ick))
> > +		clk_enable(tu->ick);
> > +
> > +	/*
> > +	 * Set initial state, so that we generate kevents only on state changes.
> > +	 */
> > +	tu->vbus_state = retu_read(rdev, TAHVO_REG_IDSR) & TAHVO_STAT_VBUS;
> > +
> > +	tu->extcon.name = DRIVER_NAME;
> > +	tu->extcon.supported_cable = tahvo_cable;
> > +	ret = extcon_dev_register(&tu->extcon, &pdev->dev);
> > +	if (ret) {
> > +		dev_err(&pdev->dev, "could not register extcon device: %d\n",
> > +			ret);
> > +		return ret;
> > +	}
> > +
> > +	/* Set the initial cable state. */
> > +	extcon_set_cable_state(&tu->extcon, "USB-HOST",
> > +			       tu->tahvo_mode == TAHVO_MODE_HOST);
> > +	extcon_set_cable_state(&tu->extcon, "USB", tu->vbus_state);
> > +
> > +	tu->irq = platform_get_irq(pdev, 0);
> > +	ret = request_threaded_irq(tu->irq, NULL, tahvo_usb_vbus_interrupt, 0,
> > +				   "tahvo-vbus", tu);
> 
> since your hardirq handler is NULL, you *must* pass IRQF_ONESHOT.

Ok.

> /Could also use devm_request_threaded_irq()

Does not really help much, since the IRQ has to be freed manually anyway
(to ensure it's disabled before usb_remove_phy(); also looks like it's
currently enabled too early...).

> > +	if (ret) {
> > +		dev_err(&pdev->dev, "could not register tahvo-vbus irq: %d\n",
> > +			ret);
> > +		goto err_disable_clk;
> > +	}
> > +
> > +	/* Attributes */
> > +	ret = device_create_file(&pdev->dev, &dev_attr_vbus_state);
> > +	ret |= device_create_file(&pdev->dev, &dev_attr_otg_mode);
> 
> heh, Greg wrote a very interesting article recently (look at his blog)
> discussing kernel/userland races wrt creation of sysfs files.

[...]

> what if someone accesses the sysfs file you've already created before
> you call dev_set_drvdata? (not sure  if it's possible).

Yes, that's a bug, will fix.

Thanks for comments,

A.
Felipe Balbi - July 9, 2013, 11:34 a.m.
Hi,

On Mon, Jul 08, 2013 at 10:44:02PM +0300, Aaro Koskinen wrote:
> > > +static void tahvo_usb_become_host(struct tahvo_usb *tu)
> > > +{
> > > +	struct retu_dev *rdev = dev_get_drvdata(tu->pt_dev->dev.parent);
> > > +
> > > +	extcon_set_cable_state(&tu->extcon, "USB-HOST", true);
> > > +
> > > +	/* Power up the transceiver in USB host mode */
> > > +	retu_write(rdev, TAHVO_REG_USBR, USBR_REGOUT | USBR_NSUSPEND |
> > > +		   USBR_MASTER_SW2 | USBR_MASTER_SW1);
> > > +	tu->phy.state = OTG_STATE_A_IDLE;
> > > +
> > > +	check_vbus_state(tu);
> > > +}
> > > +
> > > +static void tahvo_usb_stop_host(struct tahvo_usb *tu)
> > > +{
> > > +	tu->phy.state = OTG_STATE_A_IDLE;
> > 
> > shouldn't you undo tahvo_usb_become_host() here ? I mean, set the
> > transceiver to SLAVE ?
> 
> tahvo_usb_become_peripheral() (or power_off) is always called after this
> function. Actually, these stop functions can be eliminated altogether
> as they are only called from a single place...

alright, I guess GCC is already inlining them anyway, your choice.

> > > +static int tahvo_usb_set_host(struct usb_otg *otg, struct usb_bus *host)
> > > +{
> > > +	struct tahvo_usb *tu = container_of(otg->phy, struct tahvo_usb, phy);
> > > +
> > > +	dev_dbg(&tu->pt_dev->dev, "%s %p\n", __func__, host);
> > > +
> > > +	if (otg == NULL)
> > > +		return -ENODEV;
> > > +
> > > +	mutex_lock(&tu->serialize);
> > > +
> > > +	if (host == NULL) {
> > > +		if (tu->tahvo_mode == TAHVO_MODE_HOST)
> > > +			tahvo_usb_power_off(tu);
> > > +		otg->host = NULL;
> > > +		mutex_unlock(&tu->serialize);
> > > +		return 0;
> > > +	}
> > > +
> > > +	if (tu->tahvo_mode == TAHVO_MODE_HOST) {
> > > +		otg->host = NULL;
> > > +		tahvo_usb_become_host(tu);
> > > +	}
> > > +
> > > +	otg->host = host;
> > > +
> > > +	mutex_unlock(&tu->serialize);
> > > +
> > > +	return 0;
> > > +}
> > > +
> > > +static int tahvo_usb_set_peripheral(struct usb_otg *otg,
> > > +				    struct usb_gadget *gadget)
> > 
> > I want to get rid of the extra 'gadget' and 'host' parameters on
> > ->set_host() and ->set_peripheral(). Nobody really uses them other than:
> > 
> > my_phy->phy.otg->{gadget,host} = {gadget,host};
> > 
> > For that, I need all other PHYs to stop relying on those parameters and
> > I'll cook patches for that for v3.12 merge window.
> 
> How will the PHY know if there is a host/gadget driver present? I guess
> I will need to wait for those patches...

It won't. We're assuming that if the link asks to become a host, it
should already know that there is a host side available :-)

> > > +static int tahvo_usb_probe(struct platform_device *pdev)
> > > +{
> > > +	struct retu_dev *rdev = dev_get_drvdata(pdev->dev.parent);
> > > +	struct tahvo_usb *tu;
> > > +	int ret;
> > > +
> > > +	tu = devm_kzalloc(&pdev->dev, sizeof(*tu), GFP_KERNEL);
> > > +	if (!tu)
> > > +		return -ENOMEM;
> > > +
> > > +	tu->phy.otg = devm_kzalloc(&pdev->dev, sizeof(*tu->phy.otg),
> > > +				   GFP_KERNEL);
> > > +	if (!tu->phy.otg)
> > > +		return -ENOMEM;
> > > +
> > > +	tu->pt_dev = pdev;
> > > +
> > > +	/* Default mode */
> > > +#ifdef CONFIG_TAHVO_USB_HOST_BY_DEFAULT
> > > +	tu->tahvo_mode = TAHVO_MODE_HOST;
> > > +#else
> > > +	tu->tahvo_mode = TAHVO_MODE_PERIPHERAL;
> > > +#endif
> > 
> > should you call become_host()/become_peripheral() here ?
> 
> Not needed. Once the PHY is registered, the framework will call set_host /
> set_peripheral and the HW gets set to correct state.

ok good, thanks

> > /Could also use devm_request_threaded_irq()
> 
> Does not really help much, since the IRQ has to be freed manually anyway
> (to ensure it's disabled before usb_remove_phy(); also looks like it's
> currently enabled too early...).

you miss a free() in the error path. Switching to
devm_request_threaded_irq() would save you the trouble of having to call
that explicitly.

Patch

diff --git a/drivers/usb/phy/Kconfig b/drivers/usb/phy/Kconfig
index 14a50bd..a5c7937 100644
--- a/drivers/usb/phy/Kconfig
+++ b/drivers/usb/phy/Kconfig
@@ -145,6 +145,20 @@  config OMAP_OTG
 	  This driver can also be built as a module. If so, the module
 	  will be called omap-otg.
 
+config TAHVO_USB
+	tristate "Tahvo USB transceiver driver"
+	depends on MFD_RETU && EXTCON
+	help
+	  Enable this to support USB transceiver on Tahvo. This is used
+	  at least on Nokia 770.
+
+config TAHVO_USB_HOST_BY_DEFAULT
+	depends on TAHVO_USB
+	boolean "Device in USB host mode by default"
+	help
+	  Say Y here, if you want the device to enter USB host mode
+	  by default on bootup.
+
 config USB_ISP1301
 	tristate "NXP ISP1301 USB transceiver support"
 	depends on USB || USB_GADGET
diff --git a/drivers/usb/phy/Makefile b/drivers/usb/phy/Makefile
index c7f391b..f3984d1 100644
--- a/drivers/usb/phy/Makefile
+++ b/drivers/usb/phy/Makefile
@@ -13,6 +13,7 @@  phy-fsl-usb2-objs			:= phy-fsl-usb.o phy-fsm-usb.o
 obj-$(CONFIG_FSL_USB2_OTG)		+= phy-fsl-usb2.o
 obj-$(CONFIG_ISP1301_OMAP)		+= phy-isp1301-omap.o
 obj-$(CONFIG_MV_U3D_PHY)		+= phy-mv-u3d-usb.o
+obj-$(CONFIG_TAHVO_USB)			+= phy-tahvo.o
 obj-$(CONFIG_NOP_USB_XCEIV)		+= phy-nop.o
 obj-$(CONFIG_OMAP_CONTROL_USB)		+= phy-omap-control.o
 obj-$(CONFIG_OMAP_OTG)			+= phy-omap-otg.o
diff --git a/drivers/usb/phy/phy-tahvo.c b/drivers/usb/phy/phy-tahvo.c
new file mode 100644
index 0000000..a2d96a2
--- /dev/null
+++ b/drivers/usb/phy/phy-tahvo.c
@@ -0,0 +1,448 @@ 
+/*
+ * Tahvo USB transceiver driver
+ *
+ * Copyright (C) 2005-2006 Nokia Corporation
+ *
+ * Parts copied from isp1301_omap.c.
+ * Copyright (C) 2004 Texas Instruments
+ * Copyright (C) 2004 David Brownell
+ *
+ * Original driver written by Juha Yrjölä, Tony Lindgren and Timo Teräs.
+ * Modified for Retu/Tahvo MFD by Aaro Koskinen.
+ *
+ * This file is subject to the terms and conditions of the GNU General
+ * Public License. See the file "COPYING" in the main directory of this
+ * archive for more details.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/io.h>
+#include <linux/clk.h>
+#include <linux/usb.h>
+#include <linux/extcon.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/usb/otg.h>
+#include <linux/mfd/retu.h>
+#include <linux/usb/gadget.h>
+#include <linux/platform_device.h>
+
+#define DRIVER_NAME     "tahvo-usb"
+
+#define TAHVO_REG_IDSR	0x02
+#define TAHVO_REG_USBR	0x06
+
+#define USBR_SLAVE_CONTROL	(1 << 8)
+#define USBR_VPPVIO_SW		(1 << 7)
+#define USBR_SPEED		(1 << 6)
+#define USBR_REGOUT		(1 << 5)
+#define USBR_MASTER_SW2		(1 << 4)
+#define USBR_MASTER_SW1		(1 << 3)
+#define USBR_SLAVE_SW		(1 << 2)
+#define USBR_NSUSPEND		(1 << 1)
+#define USBR_SEMODE		(1 << 0)
+
+#define TAHVO_MODE_HOST		0
+#define TAHVO_MODE_PERIPHERAL	1
+
+struct tahvo_usb {
+	struct platform_device	*pt_dev;
+	struct usb_phy		phy;
+	int			vbus_state;
+	struct mutex		serialize;
+	struct clk		*ick;
+	int			irq;
+	int			tahvo_mode;
+	struct extcon_dev	extcon;
+};
+
+static const char *tahvo_cable[] = {
+	"USB-HOST",
+	"USB",
+	NULL,
+};
+
+static ssize_t vbus_state_show(struct device *device,
+			       struct device_attribute *attr, char *buf)
+{
+	struct tahvo_usb *tu = dev_get_drvdata(device);
+	return sprintf(buf, "%d\n", tu->vbus_state);
+}
+static DEVICE_ATTR(vbus_state, 0444, vbus_state_show, NULL);
+
+static void check_vbus_state(struct tahvo_usb *tu)
+{
+	struct retu_dev *rdev = dev_get_drvdata(tu->pt_dev->dev.parent);
+	int reg, prev_state;
+
+	reg = retu_read(rdev, TAHVO_REG_IDSR);
+	if (reg & TAHVO_STAT_VBUS) {
+		switch (tu->phy.state) {
+		case OTG_STATE_B_IDLE:
+			/* Enable the gadget driver */
+			if (tu->phy.otg->gadget)
+				usb_gadget_vbus_connect(tu->phy.otg->gadget);
+			tu->phy.state = OTG_STATE_B_PERIPHERAL;
+			break;
+		case OTG_STATE_A_IDLE:
+			/*
+			 * Session is now valid assuming the USB hub is driving
+			 * Vbus.
+			 */
+			tu->phy.state = OTG_STATE_A_HOST;
+			break;
+		default:
+			break;
+		}
+		dev_info(&tu->pt_dev->dev, "USB cable connected\n");
+	} else {
+		switch (tu->phy.state) {
+		case OTG_STATE_B_PERIPHERAL:
+			if (tu->phy.otg->gadget)
+				usb_gadget_vbus_disconnect(tu->phy.otg->gadget);
+			tu->phy.state = OTG_STATE_B_IDLE;
+			break;
+		case OTG_STATE_A_HOST:
+			tu->phy.state = OTG_STATE_A_IDLE;
+			break;
+		default:
+			break;
+		}
+		dev_info(&tu->pt_dev->dev, "USB cable disconnected\n");
+	}
+
+	prev_state = tu->vbus_state;
+	tu->vbus_state = reg & TAHVO_STAT_VBUS;
+	if (prev_state != tu->vbus_state) {
+		extcon_set_cable_state(&tu->extcon, "USB", tu->vbus_state);
+		sysfs_notify(&tu->pt_dev->dev.kobj, NULL, "vbus_state");
+	}
+}
+
+static void tahvo_usb_become_host(struct tahvo_usb *tu)
+{
+	struct retu_dev *rdev = dev_get_drvdata(tu->pt_dev->dev.parent);
+
+	extcon_set_cable_state(&tu->extcon, "USB-HOST", true);
+
+	/* Power up the transceiver in USB host mode */
+	retu_write(rdev, TAHVO_REG_USBR, USBR_REGOUT | USBR_NSUSPEND |
+		   USBR_MASTER_SW2 | USBR_MASTER_SW1);
+	tu->phy.state = OTG_STATE_A_IDLE;
+
+	check_vbus_state(tu);
+}
+
+static void tahvo_usb_stop_host(struct tahvo_usb *tu)
+{
+	tu->phy.state = OTG_STATE_A_IDLE;
+}
+
+static void tahvo_usb_become_peripheral(struct tahvo_usb *tu)
+{
+	struct retu_dev *rdev = dev_get_drvdata(tu->pt_dev->dev.parent);
+
+	extcon_set_cable_state(&tu->extcon, "USB-HOST", false);
+
+	/* Power up transceiver and set it in USB peripheral mode */
+	retu_write(rdev, TAHVO_REG_USBR, USBR_SLAVE_CONTROL | USBR_REGOUT |
+		   USBR_NSUSPEND | USBR_SLAVE_SW);
+	tu->phy.state = OTG_STATE_B_IDLE;
+
+	check_vbus_state(tu);
+}
+
+static void tahvo_usb_stop_peripheral(struct tahvo_usb *tu)
+{
+	if (tu->phy.otg->gadget)
+		usb_gadget_vbus_disconnect(tu->phy.otg->gadget);
+	tu->phy.state = OTG_STATE_B_IDLE;
+}
+
+static void tahvo_usb_power_off(struct tahvo_usb *tu)
+{
+	struct retu_dev *rdev = dev_get_drvdata(tu->pt_dev->dev.parent);
+
+	/* Disable gadget controller if any */
+	if (tu->phy.otg->gadget)
+		usb_gadget_vbus_disconnect(tu->phy.otg->gadget);
+
+	/* Power off transceiver */
+	retu_write(rdev, TAHVO_REG_USBR, 0);
+	tu->phy.state = OTG_STATE_UNDEFINED;
+}
+
+static int tahvo_usb_set_suspend(struct usb_phy *dev, int suspend)
+{
+	struct tahvo_usb *tu = container_of(dev, struct tahvo_usb, phy);
+	struct retu_dev *rdev = dev_get_drvdata(tu->pt_dev->dev.parent);
+	u16 w;
+
+	dev_dbg(&tu->pt_dev->dev, "%s\n", __func__);
+
+	w = retu_read(rdev, TAHVO_REG_USBR);
+	if (suspend)
+		w &= ~USBR_NSUSPEND;
+	else
+		w |= USBR_NSUSPEND;
+	retu_write(rdev, TAHVO_REG_USBR, w);
+
+	return 0;
+}
+
+static int tahvo_usb_set_host(struct usb_otg *otg, struct usb_bus *host)
+{
+	struct tahvo_usb *tu = container_of(otg->phy, struct tahvo_usb, phy);
+
+	dev_dbg(&tu->pt_dev->dev, "%s %p\n", __func__, host);
+
+	if (otg == NULL)
+		return -ENODEV;
+
+	mutex_lock(&tu->serialize);
+
+	if (host == NULL) {
+		if (tu->tahvo_mode == TAHVO_MODE_HOST)
+			tahvo_usb_power_off(tu);
+		otg->host = NULL;
+		mutex_unlock(&tu->serialize);
+		return 0;
+	}
+
+	if (tu->tahvo_mode == TAHVO_MODE_HOST) {
+		otg->host = NULL;
+		tahvo_usb_become_host(tu);
+	}
+
+	otg->host = host;
+
+	mutex_unlock(&tu->serialize);
+
+	return 0;
+}
+
+static int tahvo_usb_set_peripheral(struct usb_otg *otg,
+				    struct usb_gadget *gadget)
+{
+	struct tahvo_usb *tu = container_of(otg->phy, struct tahvo_usb, phy);
+
+	dev_dbg(&tu->pt_dev->dev, "%s %p\n", __func__, gadget);
+
+	if (!otg)
+		return -ENODEV;
+
+	mutex_lock(&tu->serialize);
+
+	if (!gadget) {
+		if (tu->tahvo_mode == TAHVO_MODE_PERIPHERAL)
+			tahvo_usb_power_off(tu);
+		tu->phy.otg->gadget = NULL;
+		mutex_unlock(&tu->serialize);
+		return 0;
+	}
+
+	tu->phy.otg->gadget = gadget;
+	if (tu->tahvo_mode == TAHVO_MODE_PERIPHERAL)
+		tahvo_usb_become_peripheral(tu);
+
+	mutex_unlock(&tu->serialize);
+
+	return 0;
+}
+
+static irqreturn_t tahvo_usb_vbus_interrupt(int irq, void *_tu)
+{
+	struct tahvo_usb *tu = _tu;
+
+	mutex_lock(&tu->serialize);
+	check_vbus_state(tu);
+	mutex_unlock(&tu->serialize);
+
+	return IRQ_HANDLED;
+}
+
+static ssize_t otg_mode_show(struct device *device,
+			     struct device_attribute *attr, char *buf)
+{
+	struct tahvo_usb *tu = dev_get_drvdata(device);
+
+	switch (tu->tahvo_mode) {
+	case TAHVO_MODE_HOST:
+		return sprintf(buf, "host\n");
+	case TAHVO_MODE_PERIPHERAL:
+		return sprintf(buf, "peripheral\n");
+	}
+
+	return -EINVAL;
+}
+
+static ssize_t otg_mode_store(struct device *device,
+			      struct device_attribute *attr,
+			      const char *buf, size_t count)
+{
+	struct tahvo_usb *tu = dev_get_drvdata(device);
+	int r;
+
+	mutex_lock(&tu->serialize);
+	if (count >= 4 && strncmp(buf, "host", 4) == 0) {
+		if (tu->tahvo_mode == TAHVO_MODE_PERIPHERAL)
+			tahvo_usb_stop_peripheral(tu);
+		tu->tahvo_mode = TAHVO_MODE_HOST;
+		if (tu->phy.otg->host) {
+			dev_info(device, "HOST mode: host controller present\n");
+			tahvo_usb_become_host(tu);
+		} else {
+			dev_info(device, "HOST mode: no host controller, powering off\n");
+			tahvo_usb_power_off(tu);
+		}
+		r = strlen(buf);
+	} else if (count >= 10 && strncmp(buf, "peripheral", 10) == 0) {
+		if (tu->tahvo_mode == TAHVO_MODE_HOST)
+			tahvo_usb_stop_host(tu);
+		tu->tahvo_mode = TAHVO_MODE_PERIPHERAL;
+		if (tu->phy.otg->gadget) {
+			dev_info(device, "PERIPHERAL mode: gadget driver present\n");
+			tahvo_usb_become_peripheral(tu);
+		} else {
+			dev_info(device, "PERIPHERAL mode: no gadget driver, powering off\n");
+			tahvo_usb_power_off(tu);
+		}
+		r = strlen(buf);
+	} else {
+		r = -EINVAL;
+	}
+	mutex_unlock(&tu->serialize);
+
+	return r;
+}
+
+static DEVICE_ATTR(otg_mode, 0644, otg_mode_show, otg_mode_store);
+
+static int tahvo_usb_probe(struct platform_device *pdev)
+{
+	struct retu_dev *rdev = dev_get_drvdata(pdev->dev.parent);
+	struct tahvo_usb *tu;
+	int ret;
+
+	tu = devm_kzalloc(&pdev->dev, sizeof(*tu), GFP_KERNEL);
+	if (!tu)
+		return -ENOMEM;
+
+	tu->phy.otg = devm_kzalloc(&pdev->dev, sizeof(*tu->phy.otg),
+				   GFP_KERNEL);
+	if (!tu->phy.otg)
+		return -ENOMEM;
+
+	tu->pt_dev = pdev;
+
+	/* Default mode */
+#ifdef CONFIG_TAHVO_USB_HOST_BY_DEFAULT
+	tu->tahvo_mode = TAHVO_MODE_HOST;
+#else
+	tu->tahvo_mode = TAHVO_MODE_PERIPHERAL;
+#endif
+
+	mutex_init(&tu->serialize);
+
+	tu->ick = devm_clk_get(&pdev->dev, "usb_l4_ick");
+	if (!IS_ERR(tu->ick))
+		clk_enable(tu->ick);
+
+	/*
+	 * Set initial state, so that we generate kevents only on state changes.
+	 */
+	tu->vbus_state = retu_read(rdev, TAHVO_REG_IDSR) & TAHVO_STAT_VBUS;
+
+	tu->extcon.name = DRIVER_NAME;
+	tu->extcon.supported_cable = tahvo_cable;
+	ret = extcon_dev_register(&tu->extcon, &pdev->dev);
+	if (ret) {
+		dev_err(&pdev->dev, "could not register extcon device: %d\n",
+			ret);
+		return ret;
+	}
+
+	/* Set the initial cable state. */
+	extcon_set_cable_state(&tu->extcon, "USB-HOST",
+			       tu->tahvo_mode == TAHVO_MODE_HOST);
+	extcon_set_cable_state(&tu->extcon, "USB", tu->vbus_state);
+
+	tu->irq = platform_get_irq(pdev, 0);
+	ret = request_threaded_irq(tu->irq, NULL, tahvo_usb_vbus_interrupt, 0,
+				   "tahvo-vbus", tu);
+	if (ret) {
+		dev_err(&pdev->dev, "could not register tahvo-vbus irq: %d\n",
+			ret);
+		goto err_disable_clk;
+	}
+
+	/* Attributes */
+	ret = device_create_file(&pdev->dev, &dev_attr_vbus_state);
+	ret |= device_create_file(&pdev->dev, &dev_attr_otg_mode);
+	if (ret)
+		dev_err(&pdev->dev, "attribute creation failed: %d\n", ret);
+
+	/* Create OTG interface */
+	tahvo_usb_power_off(tu);
+	tu->phy.dev = &pdev->dev;
+	tu->phy.state = OTG_STATE_UNDEFINED;
+	tu->phy.label = DRIVER_NAME;
+	tu->phy.set_suspend = tahvo_usb_set_suspend;
+
+	tu->phy.otg->phy = &tu->phy;
+	tu->phy.otg->set_host = tahvo_usb_set_host;
+	tu->phy.otg->set_peripheral = tahvo_usb_set_peripheral;
+
+	ret = usb_add_phy(&tu->phy, USB_PHY_TYPE_USB2);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "cannot register USB transceiver: %d\n",
+			ret);
+		goto err_free_irq;
+	}
+
+	dev_set_drvdata(&pdev->dev, tu);
+
+	return 0;
+
+err_free_irq:
+	free_irq(tu->irq, tu);
+err_disable_clk:
+	if (!IS_ERR(tu->ick))
+		clk_disable(tu->ick);
+
+	return ret;
+}
+
+static int tahvo_usb_remove(struct platform_device *pdev)
+{
+	struct tahvo_usb *tu = platform_get_drvdata(pdev);
+
+	free_irq(tu->irq, tu);
+	usb_remove_phy(&tu->phy);
+	device_remove_file(&pdev->dev, &dev_attr_vbus_state);
+	device_remove_file(&pdev->dev, &dev_attr_otg_mode);
+	extcon_dev_unregister(&tu->extcon);
+	if (!IS_ERR(tu->ick))
+		clk_disable(tu->ick);
+
+	return 0;
+}
+
+static struct platform_driver tahvo_usb_driver = {
+	.probe		= tahvo_usb_probe,
+	.remove		= tahvo_usb_remove,
+	.driver		= {
+		.name	= "tahvo-usb",
+		.owner	= THIS_MODULE,
+	},
+};
+module_platform_driver(tahvo_usb_driver);
+
+MODULE_DESCRIPTION("Tahvo USB transceiver driver");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Juha Yrjölä, Tony Lindgren, and Timo Teräs");
+MODULE_AUTHOR("Aaro Koskinen <aaro.koskinen@iki.fi>");