Add Documentation to let users enable endpoint mode in the PCI controller and add new PCI endpoint function. Signed-off-by: Kishon Vijay Abraham I <kishon@xxxxxx> --- Documentation/PCI/00-INDEX | 2 + Documentation/PCI/pci-endpoint.txt | 199 ++++++++++++++++++++++++++++++++++++ 2 files changed, 201 insertions(+) create mode 100644 Documentation/PCI/pci-endpoint.txt diff --git a/Documentation/PCI/00-INDEX b/Documentation/PCI/00-INDEX index 147231f..e422b8151 100644 --- a/Documentation/PCI/00-INDEX +++ b/Documentation/PCI/00-INDEX @@ -12,3 +12,5 @@ pci.txt - info on the PCI subsystem for device driver authors pcieaer-howto.txt - the PCI Express Advanced Error Reporting Driver Guide HOWTO +pci-endpoint.txt + - guide to add endpoint controller driver and endpoint function driver. diff --git a/Documentation/PCI/pci-endpoint.txt b/Documentation/PCI/pci-endpoint.txt new file mode 100644 index 0000000..a453aaa --- /dev/null +++ b/Documentation/PCI/pci-endpoint.txt @@ -0,0 +1,199 @@ + PCI ENDPOINT FRAMEWORK + Kishon Vijay Abraham I <kishon@xxxxxx> + +This document is a guide to use the PCI Endpoint Framework in order to create +endpoint controller driver, endpoint function driver and using configfs +interface to bind the function driver to the controller driver. + +1. Introduction + +*Linux* has a comprehensive PCI subsystem to support PCI controllers that +operates in Root Complex mode. The subsystem has capability to scan PCI bus, +assign memory resources and irq resources, load PCI driver (based on +vendorid, deviceid), support other services like hot-plug, power management, +advanced error reporting and virtual channels. + +However PCI controller IPs integrated in certain SoC is capable of operating +either in Root Complex mode or Endpoint mode. PCI Endpoint Framework will +add endpoint mode support in *Linux*. This will help to run Linux in an +EP system which can have a wide variety of use cases from testing or +validation, co-processor accelerator etc.. + +2. PCI Endpoint Core + +The PCI Endpoint Core layer comprises of 3 components: the Endpoint Controller +library, the Endpoint Function library and the configfs layer to bind the +endpoint function with the endpoint controller. + +2.1 PCI Endpoint Controller(EPC) Library + +The EPC library provides APIs to be used by the controller that can operate +in endpoint mode. It also provides APIs to be used by function driver/library +in order to implement a particular endpoint function. + +2.1.1 APIs for the PCI controller Driver + +This section lists the APIs that the PCI Endpoint core provides to be used +by the PCI controller driver. + +*) devm_pci_epc_create()/pci_epc_create() + + The PCI controller driver should implement the following ops: + * write_header: ops to populate configuration space header + * set_bar: ops to configure the BAR + * clear_bar: ops to reset the BAR + * alloc_addr_space: ops to allocate *in* PCI controller address space + * free_addr_space: ops to free the allocated address space + * raise_irq: ops to raise a legacy or MSI interrupt + * start: ops to start the PCI link + * stop: ops to stop the PCI link + + The PCI controller driver can then create a new EPC device by invoking + devm_pci_epc_create/pci_epc_create. + +*) devm_pci_epc_destroy()/pci_epc_destroy() + + The PCI controller driver can destroy the EPC device created by either + devm_pci_epc_create or pci_epc_create using devm_pci_epc_destroy() or + /pci_epc_destroy() + +2.1.2 APIs for the PCI Endpoint Function Driver + +This section lists the APIs that the PCI Endpoint core provides to be used +by the PCI endpoint function driver. + +*) pci_epc_write_header() + + The PCI endpoint function driver should use pci_epc_write_header() to + write the standard configuration header to the endpoint controller. + +*) pci_epc_set_bar() + + The PCI endpoint function driver should use pci_epc_set_bar() to configure + the Base Address Register in order for the host to assign PCI addr space. + Register space of the function driver is usually configured + using this API. + +*) pci_epc_clear_bar() + + The PCI endpoint function driver should use pci_epc_clear_bar() to reset + the BAR. + +*) pci_epc_raise_irq() + + The PCI endpoint function driver should use pci_epc_raise_irq() to raise + Legacy Interrupt or MSI Interrupt. + +*) pci_epc_start() + + The PCI endpoint function driver should invoke pci_epc_start() once it + has configured the endpoint function and wants to start the PCI link. + +*) pci_epc_stop() + + The PCI endpoint function driver should invoke pci_epc_stop() to stop + the PCI LINK. + +2.1.3 APIs for the PCI Endpoint Function Library + +This section lists the APIs that the PCI Endpoint core provides to be used +by the PCI endpoint function library. + +*) pci_epc_bind_epf() + + The PCI endpoint function library uses pci_epc_bind_epf() to bind the + function driver with a controller driver. The binding will be based on + the endpoint controller function name (as seen in /sys/class/pci_epc/). + +*) pci_epc_unbind_epf() + + The PCI endpoint function library uses pci_epc_unbind_epf() to unbind + the function driver from the controller driver. After unbind the controller + driver can be bound to any other function driver. + +2.2 PCI Endpoint Function(EPF) Library + +The EPF library provides APIs to be used by the function driver and the EPC +library in order to provide endpoint mode functionality. + +2.2.1 APIs for the PCI Endpoint Function Driver + +This section lists the APIs that the PCI Endpoint core provides to be used +by the PCI endpoint function driver. + +*) pci_epf_register_driver() + + The PCI Endpoint Function driver should implement the following ops: + * bind: ops to perform when a EPC device has been bound to EPF device + * unbind: ops to perform when a binding has been lost between a EPC + device and EPF device + * linkup: ops to perform when the EPC device has established a + connection with a host system + + The PCI Function driver can then register the PCI EPF driver by using + pci_epf_register_driver(). + +*) pci_epf_unregister_driver() + + The PCI Function driver can unregister the PCI EPF driver by using + pci_epf_unregister_driver(). + +*) pci_epf_alloc_space() + + The PCI Function driver can allocate space for a particular BAR using + pci_epf_alloc_space(). + +*) pci_epf_free_space() + + The PCI Function driver can free the allocated space + (using pci_epf_alloc_space) by invoking pci_epf_free_space(). + +2.2.2 APIs for the PCI Endpoint Controller Library + +This section lists the APIs that the PCI Endpoint core provides to be used +by the PCI endpoint controller library. + +*) pci_epf_bind() + + The PCI endpoint controller library invokes pci_epf_bind() when the EPF + device has been bound to a EPC device. + +*) pci_epf_unbind() + + The PCI endpoint controller library invokes pci_epf_unbind() when the + binding between EPC device and EPF device is lost. + +*) pci_epf_linkup() + + The PCI endpoint controller library invokes pci_epf_linkup() when the + EPC device has established the connection to the host. + +2.3 CONFIGFS + +The PCI Endpoint Core exposes configfs entry (pci_ep) in order to configure the +PCI Endpoint Function and in order to bind the endpoint function +with the endpoint controller. Every folder in pci_ep/ represent a PCI +endpoint function. + +The following entries can be used to configure the standard configuration +header of the endpoint function. + vendorid + deviceid + revid + progif_code + subclass_code + baseclass_code + cache_line_size + subsys_vendor_id + subsys_id + interrupt_pin + +The following entries has special meaning: + function: this readonly entry shows the name using which the function + driver will be bound to this function + epc : the name of the EPC device this function should be bound to. + The name of the EPC device should be from /sys/class/pci_epc. + +3. Known Limitations + +The Endpoint Core doesn't support adding multi-function devices. -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
