On Tue, May 12, 2015 at 03:14:44PM +0100, Andre Przywara wrote: > This is the fourth revision of the SBSA UART support series, now > based on the current tty-next branch. > Compared to v3 I addressed some comments Jakub had on v3 (thanks for > the review!). Also since some basic ACPI support for ARM64 is now > upstream, I include the necessary ACPI binding as a new patch 11 > on top. > ---- > > The ARM Server Base System Architecture[1] document describes a > generic UART which is a subset of the ARM PL011 UART. > It lacks DMA support, baud rate control and modem status line > control, among other things. > The idea is to move the UART initialization and setup into the > firmware (which does this job today already) and let the kernel just > use the UART for sending and receiving characters. > > This patchset integrates support for this UART subset into the > existing PL011 driver - basically by refactoring some > functions and providing a new uart_ops structure for it. It also has > a separate probe function to be not dependent on AMBA/PrimeCell. > It provides a device tree and an ACPI binding. > Beside the obvious effect of code sharing reusing most of the PL011 > code has the advantage of not introducing another serial device > prefix, so it can go with ttyAMA, which seems to be pretty common. > As changing the baudrate and other communication parameters is not > specified for the SBSA UART, any userland attempt will be denied by > the kernel. The device-tree provided fixed baud rate will be > reported, so stty for instance prints the right value. > > This series is based on Greg's tty-next branch, a git repo can > be found at [2] (branch sbsa-uart/v4). > > Patch 1/11 contains a bug fix which applies to the PL011 part also, > it should be considered regardless of the rest of the series. > According to Russell this is still racy, but still better than the > current solution. > Patch 2-7 refactor some PL011 functions by splitting them up into > smaller pieces, so that most of the code can be reused later by the > SBSA part. > Patch 8 and 9 introduce two new properties for the vendor structure, > this is for SBSA functionality which cannot be controlled by > separate uart_ops members only. > Patch 10 then finally drops in the SBSA specific code, by providing > a new uart_ops, vendor struct and probe function for it. Also the new > device tree binding is documented. > Patch 11 adds the necessary ACPI boilerplate. > > For testing you should be able to take any hardware which has a PL011 > and change the DT to use a "arm,sbsa-uart" compatible string and the > baud rate with the "current-speed" property. > Of course testing with a real SBSA Generic UART is welcomed - as well > as regression testing with any PL011 implementation. > I tested this on a FastModel, a Juno and a Midway machine, both in > PL011 and in (DT-emulated) SBSA mode. > > Changelog: > v3 .. v4: > - fixed rebase artifact > - moved memory allocation out of pl011_allocate_port() function > (and consequently renamed that to pl011_find_free_port) > - added ACPI driver binding > > v2 .. v3: > - rebased on top of tty-next and Dave's latest PL011 rework > - fixed module build > - removed redundant =NULL members in sbsa_uart_ops > > v1 .. v2: > - rebased on top of 4.0-rc1 and Dave's newest PL011 fix [3] > - added mandatory current-speed property and report that to userland > > Cheers, > Andre > > [1] ARM-DEN-0029 Server Base System Architecture, available (click- > thru...) from http://infocenter.arm.com > [2] http://www.linux-arm.org/git?p=linux-ap.git > git://linux-arm.org/linux-ap.git > [3] http://lists.infradead.org/pipermail/linux-arm-kernel/2015-March/327631.html > > Andre Przywara (10): > drivers: PL011: avoid potential unregister_driver call > drivers: PL011: refactor pl011_startup() > drivers: PL011: refactor pl011_shutdown() > drivers: PL011: refactor pl011_set_termios() > drivers: PL011: refactor pl011_probe() > drivers: PL011: replace UART_MIS reading with _RIS & _IMSC > drivers: PL011: move cts_event workaround into separate function > drivers: PL011: allow avoiding UART enabling/disabling > drivers: PL011: allow to supply fixed option string > drivers: PL011: add support for the ARM SBSA generic UART > > Graeme Gregory (1): > drivers: PL011: add ACPI probing for SBSA UART > > .../devicetree/bindings/serial/arm_sbsa_uart.txt | 10 + > drivers/tty/serial/amba-pl011.c | 547 +++++++++++++++------ > 2 files changed, 409 insertions(+), 148 deletions(-) > create mode 100644 Documentation/devicetree/bindings/serial/arm_sbsa_uart.txt Tested-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
