{"action":"opened","issue":{"url":"https://api.github.com/repos/linux-sunxi/u-boot-sunxi/issues/85","labels_url":"https://api.github.com/repos/linux-sunxi/u-boot-sunxi/issues/85/labels{/name}","comments_url":"https://api.github.com/repos/linux-sunxi/u-boot-sunxi/issues/85/comments","events_url":"https://api.github.com/repos/linux-sunxi/u-boot-sunxi/issues/85/events","html_url":"https://github.com/linux-sunxi/u-boot-sunxi/issues/85","id":92880514,"number":85,"title":"UART_2 usage on A20","user":{"login":"nico-meetprizm","id":13032363,"avatar_url":"https://avatars.githubusercontent.com/u/13032363?v=3","gravatar_id":"","url":"https://api.github.com/users/nico-meetprizm","html_url":"https://github.com/nico-meetprizm","followers_url":"https://api.github.com/users/nico-meetprizm/followers","following_url":"https://api.github.com/users/nico-meetprizm/following{/other_user}","gists_url":"https://api.github.com/users/nico-meetprizm/gists{/gist_id}","starred_url":"https://api.github.com/users/nico-meetprizm/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/nico-meetprizm/subscriptions","organizations_url":"https://api.github.com/users/nico-meetprizm/orgs","repos_url":"https://api.github.com/users/nico-meetprizm/repos","events_url":"https://api.github.com/users/nico-meetprizm/events{/privacy}","received_events_url":"https://api.github.com/users/nico-meetprizm/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":0,"created_at":"2015-07-03T13:51:44Z","updated_at":"2015-07-03T13:51:44Z","closed_at":null,"body":"Hi everybody,\r\n\r\nI'm using the u-boot from the lichee-dev-a20 branch and my goal is to use the A20's UART2 in uboot to communicate with some other component on my board but I can't quite figure it out.\r\n\r\nFrom what i've gathered 'drivers/serial/serial.c' is the one responsible for initialising the serial in the function 'int serial_init (void)'. So i modified the code to also init the UART_2, the one refered as 'CONFIG_SYS_NS16550_COM3' in  the driver 'ns16550'.\r\n\r\nWhen I modify any of the UARTs registers either using the 'NS16550_t' structure, or directly with a pointer to the right address, it doesn't work, meaning I always read back 0x00 for every register I write.\r\nFor instance I tried to write 0xBB in the 'UART_SCH' register (offset = 0x1C) for UART_1,2,3,4 and when I read it back only the one for UART_1 retained my value, all of the others are read as 0.\r\n\r\nIt almost feels like I can't modify them, as if the MMU or something prevented me from configuring my UART's but as far as I know it's supposed to be disabled.\r\n\r\nAny help would be greatly appreciated ! Thanks !!"}}