diff mbox series

[RFC,1/3] usb: Add USB repeater generic framework

Message ID 20221116123019.2753230-2-abel.vesa@linaro.org (mailing list archive)
State Not Applicable
Headers show
Series usb: Add generic repeater framework and SM8550 driver | expand

Commit Message

Abel Vesa Nov. 16, 2022, 12:30 p.m. UTC
With more SoCs moving towards eUSB2, such platforms will have to use
a USB 2.0 compliance repeater. This repeater HW-wise usually deals with
level shifting, but depending on the implementation it can do much more.
So add a ganeric USB framework that would allow either a generic PHY or
some USB host controller to control and get a repeater from a devicetree
phandle. This framework will further be used by platform specific
drivers to register the repeater and implement platform specific ops.

Signed-off-by: Abel Vesa <abel.vesa@linaro.org>
---
 drivers/usb/Kconfig             |   2 +
 drivers/usb/Makefile            |   2 +
 drivers/usb/repeater/Kconfig    |   9 ++
 drivers/usb/repeater/Makefile   |   6 +
 drivers/usb/repeater/repeater.c | 198 ++++++++++++++++++++++++++++++++
 include/linux/usb/repeater.h    |  78 +++++++++++++
 6 files changed, 295 insertions(+)
 create mode 100644 drivers/usb/repeater/Kconfig
 create mode 100644 drivers/usb/repeater/Makefile
 create mode 100644 drivers/usb/repeater/repeater.c
 create mode 100644 include/linux/usb/repeater.h

Comments

Andrzej Pietrasiewicz Nov. 18, 2022, 8:59 a.m. UTC | #1
Hi Abel,

W dniu 16.11.2022 o 13:30, Abel Vesa pisze:
> With more SoCs moving towards eUSB2, 

Can you name a few?

such platforms will have to use
> a USB 2.0 compliance repeater. This repeater HW-wise usually deals with
> level shifting, but depending on the implementation it can do much more.
> So add a ganeric USB framework that would allow either a generic PHY or
> some USB host controller to control and get a repeater from a devicetree
> phandle. This framework will further be used by platform specific
> drivers to register the repeater and implement platform specific ops.
> 
> Signed-off-by: Abel Vesa <abel.vesa@linaro.org>
> ---
>   drivers/usb/Kconfig             |   2 +
>   drivers/usb/Makefile            |   2 +
>   drivers/usb/repeater/Kconfig    |   9 ++
>   drivers/usb/repeater/Makefile   |   6 +
>   drivers/usb/repeater/repeater.c | 198 ++++++++++++++++++++++++++++++++
>   include/linux/usb/repeater.h    |  78 +++++++++++++
>   6 files changed, 295 insertions(+)
>   create mode 100644 drivers/usb/repeater/Kconfig
>   create mode 100644 drivers/usb/repeater/Makefile
>   create mode 100644 drivers/usb/repeater/repeater.c
>   create mode 100644 include/linux/usb/repeater.h
> 

<snip>

> diff --git a/include/linux/usb/repeater.h b/include/linux/usb/repeater.h
> new file mode 100644
> index 000000000000..e68e0936f1e5
> --- /dev/null
> +++ b/include/linux/usb/repeater.h
> @@ -0,0 +1,78 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * USB Repeater defines
> + */
> +
> +#ifndef __LINUX_USB_REPEATER_H
> +#define __LINUX_USB_REPEATER_H
> +
> +struct usb_repeater {
> +	struct device		*dev;
> +	const char		*label;
> +	unsigned int		 flags;
> +
> +	struct list_head	head;

This member serves the purpose of a list _entry_, no?
The _head_ is static LIST_HEAD(usb_repeater_list);
Maybe call it "entry"?

> +	int	(*reset)(struct usb_repeater *rptr, bool assert);
> +	int	(*init)(struct usb_repeater *rptr);
> +	int	(*power_on)(struct usb_repeater *rptr);
> +	int	(*power_off)(struct usb_repeater *rptr);

Would you document these ops somehow? Potential driver writers need to
understand when they are called and what they are supposed to do.
In particular, how do these relate to what's in "Embedded USB2 (eUSB2)
Physical Layer Supplement to the USB Revision 2.0 Specification"?

Regards,

Andrzej
Abel Vesa Nov. 21, 2022, 2:21 p.m. UTC | #2
On 22-11-18 09:59:43, Andrzej Pietrasiewicz wrote:
> Hi Abel,
> 
> W dniu 16.11.2022 o 13:30, Abel Vesa pisze:
> > With more SoCs moving towards eUSB2,
> 
> Can you name a few?

Right now, for SoCs, I can only name the SM8550 from Qualcomm. But I
would think there will be more from now on, not just from Qualcomm.

But I found a couple of more repeaters already existent. Like TUSB2E11
or TUSB2E22 from TI or PTN3222 from NXP. I'm not sure if they are used
already alongside any specific SoC though (yet).

Anyway, I can rephrase that.

> 
> such platforms will have to use
> > a USB 2.0 compliance repeater. This repeater HW-wise usually deals with
> > level shifting, but depending on the implementation it can do much more.
> > So add a ganeric USB framework that would allow either a generic PHY or
> > some USB host controller to control and get a repeater from a devicetree
> > phandle. This framework will further be used by platform specific
> > drivers to register the repeater and implement platform specific ops.
> > 
> > Signed-off-by: Abel Vesa <abel.vesa@linaro.org>
> > ---
> >   drivers/usb/Kconfig             |   2 +
> >   drivers/usb/Makefile            |   2 +
> >   drivers/usb/repeater/Kconfig    |   9 ++
> >   drivers/usb/repeater/Makefile   |   6 +
> >   drivers/usb/repeater/repeater.c | 198 ++++++++++++++++++++++++++++++++
> >   include/linux/usb/repeater.h    |  78 +++++++++++++
> >   6 files changed, 295 insertions(+)
> >   create mode 100644 drivers/usb/repeater/Kconfig
> >   create mode 100644 drivers/usb/repeater/Makefile
> >   create mode 100644 drivers/usb/repeater/repeater.c
> >   create mode 100644 include/linux/usb/repeater.h
> > 
> 
> <snip>
> 
> > diff --git a/include/linux/usb/repeater.h b/include/linux/usb/repeater.h
> > new file mode 100644
> > index 000000000000..e68e0936f1e5
> > --- /dev/null
> > +++ b/include/linux/usb/repeater.h
> > @@ -0,0 +1,78 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +/*
> > + * USB Repeater defines
> > + */
> > +
> > +#ifndef __LINUX_USB_REPEATER_H
> > +#define __LINUX_USB_REPEATER_H
> > +
> > +struct usb_repeater {
> > +	struct device		*dev;
> > +	const char		*label;
> > +	unsigned int		 flags;
> > +
> > +	struct list_head	head;
> 
> This member serves the purpose of a list _entry_, no?
> The _head_ is static LIST_HEAD(usb_repeater_list);
> Maybe call it "entry"?

Sure thing. Will do.

> 
> > +	int	(*reset)(struct usb_repeater *rptr, bool assert);
> > +	int	(*init)(struct usb_repeater *rptr);
> > +	int	(*power_on)(struct usb_repeater *rptr);
> > +	int	(*power_off)(struct usb_repeater *rptr);
> 
> Would you document these ops somehow? Potential driver writers need to
> understand when they are called and what they are supposed to do.
> In particular, how do these relate to what's in "Embedded USB2 (eUSB2)
> Physical Layer Supplement to the USB Revision 2.0 Specification"?

Yes. Will document them appropriately.

> 
> Regards,
> 
> Andrzej

Thanks,
Abel
diff mbox series

Patch

diff --git a/drivers/usb/Kconfig b/drivers/usb/Kconfig
index a871a988829d..c9ad102a0fa9 100644
--- a/drivers/usb/Kconfig
+++ b/drivers/usb/Kconfig
@@ -176,6 +176,8 @@  source "drivers/usb/gadget/Kconfig"
 
 source "drivers/usb/typec/Kconfig"
 
+source "drivers/usb/repeater/Kconfig"
+
 source "drivers/usb/roles/Kconfig"
 
 endif # USB_SUPPORT
diff --git a/drivers/usb/Makefile b/drivers/usb/Makefile
index a81e6ef293af..c96c66304edd 100644
--- a/drivers/usb/Makefile
+++ b/drivers/usb/Makefile
@@ -67,4 +67,6 @@  obj-$(CONFIG_USBIP_CORE)	+= usbip/
 
 obj-$(CONFIG_TYPEC)		+= typec/
 
+obj-$(CONFIG_USB_REPEATER)	+= repeater/
+
 obj-$(CONFIG_USB_ROLE_SWITCH)	+= roles/
diff --git a/drivers/usb/repeater/Kconfig b/drivers/usb/repeater/Kconfig
new file mode 100644
index 000000000000..e12cd22c0adb
--- /dev/null
+++ b/drivers/usb/repeater/Kconfig
@@ -0,0 +1,9 @@ 
+# SPDX-License-Identifier: GPL-2.0
+
+config USB_REPEATER
+	tristate "USB Repeater Framework"
+	help
+	  Enable this to allow the USB PHY drivers and the connected repeater
+	  driver to bind together and to provide the USB driver ways to perform
+	  set of operations with repeater for USB2 functionality using PHY and
+	  controller driver.
diff --git a/drivers/usb/repeater/Makefile b/drivers/usb/repeater/Makefile
new file mode 100644
index 000000000000..2d1b5f348976
--- /dev/null
+++ b/drivers/usb/repeater/Makefile
@@ -0,0 +1,6 @@ 
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for USB repeater drivers
+#
+
+obj-$(CONFIG_USB_REPEATER)		+= repeater.o
diff --git a/drivers/usb/repeater/repeater.c b/drivers/usb/repeater/repeater.c
new file mode 100644
index 000000000000..e97a95422735
--- /dev/null
+++ b/drivers/usb/repeater/repeater.c
@@ -0,0 +1,198 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2022, Qualcomm Innovation Center, Inc. All rights reserved.
+ * Copyright (c) 2022, Linaro Limited
+ */
+
+#include <linux/device.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/overflow.h>
+
+#include <linux/usb/repeater.h>
+
+static LIST_HEAD(usb_repeater_list);
+static DEFINE_SPINLOCK(usb_repeater_lock);
+
+/**
+ * usb_put_repeater - release the USB repeater
+ * @rptr: the repeater returned by usb_get_repeater()
+ *
+ * Releases a refcount the caller received from usb_get_repeater().
+ *
+ * For use by USB PHY drivers.
+ */
+void usb_put_repeater(struct usb_repeater *rptr)
+{
+	if (rptr) {
+		put_device(rptr->dev);
+		if (rptr->dev->driver && rptr->dev->driver->owner) {
+			struct module *owner = rptr->dev->driver->owner;
+
+			module_put(owner);
+		}
+	}
+}
+EXPORT_SYMBOL_GPL(usb_put_repeater);
+
+static struct usb_repeater *of_usb_find_repeater(struct device_node *node)
+{
+	struct usb_repeater *rptr;
+
+	if (!of_device_is_available(node))
+		return ERR_PTR(-ENODEV);
+
+	list_for_each_entry(rptr, &usb_repeater_list, head) {
+		if (node != rptr->dev->of_node)
+			continue;
+
+		return rptr;
+	}
+
+	return ERR_PTR(-EPROBE_DEFER);
+}
+
+static void devm_usb_repeater_release(struct device *dev, void *res)
+{
+	struct usb_repeater *rptr = *(struct usb_repeater **)res;
+
+	usb_put_repeater(rptr);
+}
+
+/**
+ * devm_usb_get_repeater_by_node - find the USB repeater by device_node
+ * @dev: device that requests this USB repeater
+ * @node: the device_node for the USB repeater device.
+ * @nb: a notifier_block to register with the USB repeater.
+ *
+ * Returns the USB repeater driver associated with the given device_node,
+ * after getting a refcount to it, -ENODEV if there is no such repeater or
+ * -EPROBE_DEFER if the device is not yet loaded. While at that, it
+ * also associates the device with
+ * the repeater using devres. On driver detach, release function is invoked
+ * on the devres data, then, devres data is freed.
+ *
+ * For use by peripheral drivers for devices related to a repeater,
+ * such as a charger.
+ */
+struct  usb_repeater *devm_usb_get_repeater_by_node(struct device *dev,
+					  struct device_node *node,
+					  struct notifier_block *nb)
+{
+	struct usb_repeater *rptr = ERR_PTR(-ENOMEM);
+	struct usb_repeater *rptr_devm;
+	unsigned long flags;
+
+	rptr_devm = devres_alloc(devm_usb_repeater_release,
+					sizeof(*rptr_devm), GFP_KERNEL);
+	if (!rptr_devm) {
+		dev_dbg(dev, "failed to allocate memory for devres\n");
+		goto err0;
+	}
+
+	spin_lock_irqsave(&usb_repeater_lock, flags);
+
+	rptr = of_usb_find_repeater(node);
+	if (IS_ERR(rptr)) {
+		devres_free(rptr_devm);
+		goto err0;
+	}
+
+	if (!try_module_get(rptr->dev->driver->owner)) {
+		rptr = ERR_PTR(-ENODEV);
+		devres_free(rptr_devm);
+		goto err0;
+	}
+	devres_add(dev, rptr_devm);
+
+	get_device(rptr->dev);
+err0:
+	spin_unlock_irqrestore(&usb_repeater_lock, flags);
+
+	return rptr;
+}
+EXPORT_SYMBOL_GPL(devm_usb_get_repeater_by_node);
+
+/**
+ * devm_usb_get_repeater_by_phandle - find the USB repeater by phandle
+ * @dev: device that requests this repeater
+ * @phandle: name of the property holding the repeater phandle value
+ * @index: the index of the repeater
+ *
+ * Returns the USB repeater driver associated with the given phandle value,
+ * after getting a refcount to it, -ENODEV if there is no such repeater or
+ * -EPROBE_DEFER if there is a phandle to the repeater, but the device is
+ * not yet loaded. While at that, it also associates the device with
+ * the repeater using devres. On driver detach, release function is invoked
+ * on the devres data, then, devres data is freed.
+ *
+ * For use by USB PHY drivers.
+ */
+struct usb_repeater *devm_usb_get_repeater_by_phandle(struct device *dev,
+	const char *phandle, u8 index)
+{
+	struct device_node *node;
+	struct usb_repeater *rptr;
+
+	if (!dev->of_node) {
+		dev_dbg(dev, "device does not have a device node entry\n");
+		return ERR_PTR(-EINVAL);
+	}
+
+	node = of_parse_phandle(dev->of_node, phandle, index);
+	if (!node) {
+		dev_dbg(dev, "failed to get %s phandle in %pOF node\n", phandle,
+			dev->of_node);
+		return ERR_PTR(-ENODEV);
+	}
+	rptr = devm_usb_get_repeater_by_node(dev, node, NULL);
+	of_node_put(node);
+	return rptr;
+}
+EXPORT_SYMBOL_GPL(devm_usb_get_repeater_by_phandle);
+
+/**
+ * usb_add_repeater_dev - declare the USB repeater
+ * @rptr: the USB repeater to be used; or NULL
+ *
+ * This call is exclusively for use by repeater drivers to
+ * register the device to allow the USB phy driver to control it
+ * via repeater specific ops.
+ */
+int usb_add_repeater_dev(struct usb_repeater *rptr)
+{
+	unsigned long flags;
+
+	if (!rptr->dev) {
+		dev_err(rptr->dev, "no device provided for repeater\n");
+		return -EINVAL;
+	}
+
+	spin_lock_irqsave(&usb_repeater_lock, flags);
+	list_add_tail(&rptr->head, &usb_repeater_list);
+	spin_unlock_irqrestore(&usb_repeater_lock, flags);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(usb_add_repeater_dev);
+
+/**
+ * usb_remove_repeater - remove the USB repeater
+ * @rptr: the USB Repeater to be removed;
+ *
+ * This reverts the effects of usb_add_repeater_dev
+ */
+void usb_remove_repeater_dev(struct usb_repeater *rptr)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&usb_repeater_lock, flags);
+	if (rptr)
+		list_del(&rptr->head);
+	spin_unlock_irqrestore(&usb_repeater_lock, flags);
+}
+EXPORT_SYMBOL_GPL(usb_remove_repeater_dev);
+
+MODULE_DESCRIPTION("USB Repeater Framework");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/usb/repeater.h b/include/linux/usb/repeater.h
new file mode 100644
index 000000000000..e68e0936f1e5
--- /dev/null
+++ b/include/linux/usb/repeater.h
@@ -0,0 +1,78 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * USB Repeater defines
+ */
+
+#ifndef __LINUX_USB_REPEATER_H
+#define __LINUX_USB_REPEATER_H
+
+struct usb_repeater {
+	struct device		*dev;
+	const char		*label;
+	unsigned int		 flags;
+
+	struct list_head	head;
+	int	(*reset)(struct usb_repeater *rptr, bool assert);
+	int	(*init)(struct usb_repeater *rptr);
+	int	(*power_on)(struct usb_repeater *rptr);
+	int	(*power_off)(struct usb_repeater *rptr);
+};
+
+#if IS_ENABLED(CONFIG_USB_REPEATER)
+extern struct usb_repeater *devm_usb_get_repeater_by_phandle(struct device *dev,
+	const char *phandle, u8 index);
+extern struct usb_repeater *devm_usb_get_repeater_by_node(struct device *dev,
+	struct device_node *node, struct notifier_block *nb);
+extern int usb_add_repeater_dev(struct usb_repeater *rptr);
+extern void usb_remove_repeater_dev(struct usb_repeater *rptr);
+#else
+static inline struct usb_repeater *devm_usb_get_repeater_by_phandle(struct device *dev,
+	const char *phandle, u8 index)
+{
+	return ERR_PTR(-ENXIO);
+}
+
+static inline struct usb_repeater *devm_usb_get_repeater_by_node(struct device *dev,
+	struct device_node *node, struct notifier_block *nb)
+{
+	return ERR_PTR(-ENXIO);
+}
+
+static inline int usb_add_repeater_dev(struct usb_repeater *rptr) { return 0; }
+static inline void usb_remove_repeater_dev(struct usb_repeater *rptr) { }
+
+#endif
+
+static inline int usb_repeater_reset(struct usb_repeater *rptr, bool assert)
+{
+	if (rptr && rptr->reset != NULL)
+		return rptr->reset(rptr, assert);
+	else
+		return 0;
+}
+
+static inline int usb_repeater_init(struct usb_repeater *rptr)
+{
+	if (rptr && rptr->init != NULL)
+		return rptr->init(rptr);
+	else
+		return 0;
+}
+
+static inline int usb_repeater_power_on(struct usb_repeater *rptr)
+{
+	if (rptr && rptr->power_on != NULL)
+		return rptr->power_on(rptr);
+	else
+		return 0;
+}
+
+static inline int usb_repeater_power_off(struct usb_repeater *rptr)
+{
+	if (rptr && rptr->power_off != NULL)
+		return rptr->power_off(rptr);
+	else
+		return 0;
+}
+
+#endif /* __LINUX_USB_REPEATER_H */