There are some typos. Please correct them, thanks.
On 03/26/2015 02:23 AM, Simon Glass wrote:
Add some documentation describing how USB is implemented with USB. This
might make things easier for people to understand.
Signed-off-by: Simon Glass <s...@chromium.org>
---
Changes in v2:
- Rewrite and expand series to support driver model fully
doc/driver-model/usb-info.txt | 415 ++++++++++++++++++++++++++++++++++++++++++
1 file changed, 415 insertions(+)
create mode 100644 doc/driver-model/usb-info.txt
diff --git a/doc/driver-model/usb-info.txt b/doc/driver-model/usb-info.txt
new file mode 100644
index 0000000..3762b6c
--- /dev/null
+++ b/doc/driver-model/usb-info.txt
@@ -0,0 +1,415 @@
+How USB works with driver model
+===============================
+
+Introduction
+------------
+
+Driver model USB support makes use of existing features but changes how
+drivers are found. This document provides some information intended to help
+understand how things work with USB in U-Boot when driver model is enabled.
+
+
+Enabling driver model for USB
+-----------------------------
+
+A new CONFIG_DM_USB option is provided to enable driver model for USB. This
+causes the USB uclass to be included, and drops the equivalent code in
+usb.c. In particular the usb_init() function is then implemented by the
+uclass.
+
+
+Support for ECHI and XCHI
EHCI
XHCI
+-------------------------
+
+So far OHCI is not supported. Both EHCI and XHCI drivers should be declared
+as drivers in the USB uclass. For example:
+
+static const struct udevice_id ehci_usb_ids[] = {
+ { .compatible = "nvidia,tegra20-ehci", .data = USB_CTLR_T20 },
+ { .compatible = "nvidia,tegra30-ehci", .data = USB_CTLR_T30 },
+ { .compatible = "nvidia,tegra114-ehci", .data = USB_CTLR_T114 },
+ { }
+};
+
+U_BOOT_DRIVER(usb_ehci) = {
+ .name = "ehci_tegra",
+ .id = UCLASS_USB,
+ .of_match = ehci_usb_ids,
+ .ofdata_to_platdata = ehci_usb_ofdata_to_platdata,
+ .probe = tegra_ehci_usb_probe,
+ .remove = tegra_ehci_usb_remove,
+ .ops = &ehci_usb_ops,
+ .platdata_auto_alloc_size = sizeof(struct usb_platdata),
+ .priv_auto_alloc_size = sizeof(struct fdt_usb),
+ .flags = DM_FLAG_ALLOC_PRIV_DMA,
+};
+
+Here ehci_usb_ids is used to list the controllers that the driver supports.
+Each has its own data value. Controllers must be in the UCLASS_USB uclass.
+
+The ofdata_to_platdata() method allows the controller driver to grab any
+necessary settings from the device tree.
+
+The ops here are ehci_usb_ops. All EHCI drivers will use these same ops in
+most cases, since they are all ECHI-compatible. For ECHI there are also some
EHCI-compatible
For EHCI
+special operations that can be overriden when calling ehci_register().
overridden
+This defines a single controller, containing a root hub (which is required).
+The hub is emulated by a hub emulator, and the emulated hub has a single
+flash stick to emulate on one of its ports.
+
+When 'usb start' is used, the following 'dm tree' output will be available:
+
+ usb [ + ] `-- usb@1
+ usb_hub [ + ] `-- hub
+ usb_emul [ + ] |-- hub-emul
+ usb_emul [ + ] | `-- flash-stick
+ usb_mass_st [ + ] `-- usb_mass_storage
+
+
+This may look a confusing. Most of it mirrors the device tree, but the
may look confusing
--nvpublic
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