1Spear PCIe Gadget Driver: 2 3Author 4============= 5Pratyush Anand (pratyush.anand@gmail.com) 6 7Location 8============ 9driver/misc/spear13xx_pcie_gadget.c 10 11Supported Chip: 12=================== 13SPEAr1300 14SPEAr1310 15 16Menuconfig option: 17========================== 18Device Drivers 19 Misc devices 20 PCIe gadget support for SPEAr13XX platform 21purpose 22=========== 23This driver has several nodes which can be read/written by configfs interface. 24Its main purpose is to configure selected dual mode PCIe controller as device 25and then program its various registers to configure it as a particular device 26type. This driver can be used to show spear's PCIe device capability. 27 28Description of different nodes: 29================================= 30 31read behavior of nodes: 32------------------------------ 33link :gives ltssm status. 34int_type :type of supported interrupt 35no_of_msi :zero if MSI is not enabled by host. A positive value is the 36 number of MSI vector granted. 37vendor_id :returns programmed vendor id (hex) 38device_id :returns programmed device id(hex) 39bar0_size: :returns size of bar0 in hex. 40bar0_address :returns address of bar0 mapped area in hex. 41bar0_rw_offset :returns offset of bar0 for which bar0_data will return value. 42bar0_data :returns data at bar0_rw_offset. 43 44write behavior of nodes: 45------------------------------ 46link :write UP to enable ltsmm DOWN to disable 47int_type :write interrupt type to be configured and (int_type could be 48 INTA, MSI or NO_INT). Select MSI only when you have programmed 49 no_of_msi node. 50no_of_msi :number of MSI vector needed. 51inta :write 1 to assert INTA and 0 to de-assert. 52send_msi :write MSI vector to be sent. 53vendor_id :write vendor id(hex) to be programmed. 54device_id :write device id(hex) to be programmed. 55bar0_size :write size of bar0 in hex. default bar0 size is 1000 (hex) 56 bytes. 57bar0_address :write address of bar0 mapped area in hex. (default mapping of 58 bar0 is SYSRAM1(E0800000). Always program bar size before bar 59 address. Kernel might modify bar size and address for alignment, so 60 read back bar size and address after writing to cross check. 61bar0_rw_offset :write offset of bar0 for which bar0_data will write value. 62bar0_data :write data to be written at bar0_rw_offset. 63 64Node programming example 65=========================== 66Program all PCIe registers in such a way that when this device is connected 67to the PCIe host, then host sees this device as 1MB RAM. 68#mount -t configfs none /Config 69For nth PCIe Device Controller 70# cd /config/pcie_gadget.n/ 71Now you have all the nodes in this directory. 72program vendor id as 0x104a 73# echo 104A >> vendor_id 74 75program device id as 0xCD80 76# echo CD80 >> device_id 77 78program BAR0 size as 1MB 79# echo 100000 >> bar0_size 80 81check for programmed bar0 size 82# cat bar0_size 83 84Program BAR0 Address as DDR (0x2100000). This is the physical address of 85memory, which is to be made visible to PCIe host. Similarly any other peripheral 86can also be made visible to PCIe host. E.g., if you program base address of UART 87as BAR0 address then when this device will be connected to a host, it will be 88visible as UART. 89# echo 2100000 >> bar0_address 90 91program interrupt type : INTA 92# echo INTA >> int_type 93 94go for link up now. 95# echo UP >> link 96 97It will have to be insured that, once link up is done on gadget, then only host 98is initialized and start to search PCIe devices on its port. 99 100/*wait till link is up*/ 101# cat link 102wait till it returns UP. 103 104To assert INTA 105# echo 1 >> inta 106 107To de-assert INTA 108# echo 0 >> inta 109 110if MSI is to be used as interrupt, program no of msi vector needed (say4) 111# echo 4 >> no_of_msi 112 113select MSI as interrupt type 114# echo MSI >> int_type 115 116go for link up now 117# echo UP >> link 118 119wait till link is up 120# cat link 121An application can repetitively read this node till link is found UP. It can 122sleep between two read. 123 124wait till msi is enabled 125# cat no_of_msi 126Should return 4 (number of requested MSI vector) 127 128to send msi vector 2 129# echo 2 >> send_msi 130#cd - 131