kernel/git/stable/linux.git/drivers/serial/amba-pl011.c, branch master

tty: move drivers/serial/ to drivers/tty/serial/

2011-01-13T20:10:18+00:00

The serial drivers are really just tty drivers, so move them to drivers/tty/ to make things a bit neater overall. This is part of the tty/serial driver movement proceedure as proposed by Arnd Bergmann and approved by everyone involved a number of months ago. Cc: Arnd Bergmann Cc: Alan Cox Cc: Geert Uytterhoeven Cc: Rogier Wolff Cc: Michael H. Warfield Signed-off-by: Greg Kroah-Hartman

ARM: PL011: add DMA burst threshold support for ST variants

2011-01-05T16:58:53+00:00

ST Micro variants has some specific dma burst threshold compensation, which allows them to make better use of a DMA controller. Add support to set this up. Based on a patch from Linus Walleij. Acked-by: Linus Walleij Signed-off-by: Russell King

ARM: PL011: Add support for transmit DMA

2011-01-05T16:58:48+00:00

Add DMA engine support for transmit to the PL011 driver. Based on a patch from Linus Walliej, with the following changes: - remove RX DMA support. As PL011 doesn't give us receive timeout interrupts, we only get notified of received data when the RX DMA has completed. This rather sucks for interactive use of the TTY. - remove abuse of completions. Completions are supposed to be for events, not to tell what condition buffers are in. Replace it with a simple 'queued' bool. - fix locking - it is only safe to access the circular buffer with the port lock held. - only map the DMA buffer when required - if we're ever behind an IOMMU this helps keep IOMMU usage down, and also ensures that we're legal when we change the scatterlist entry length. - fix XON/XOFF sending - we must send XON/XOFF characters out as soon as possible - waiting for up to 4095 characters in the DMA buffer to be sent first is not acceptable. - fix XON/XOFF receive handling - we need to stop DMA when instructed to by the TTY layer, and restart it again when instructed to. There is a subtle problem here: we must not completely empty the circular buffer with DMA, otherwise we will not be notified of XON. - change the 'enable_dma' flag into a 'using DMA' flag, and track whether we can use TX DMA by whether the channel pointer is non-NULL. This gives us more control over whether we use DMA in the driver. - we don't need to have the TX DMA buffer continually allocated for each port - instead, allocate it when the port starts up, and free it when it's shut down. Update the 'using DMA' flag if we get the buffer, and adjust the TTY FIFO size appropriately. - if we're going to use PIO to send characters, use the existing IRQ based functionality rather than reimplementing it. This also ensures we call uart_write_wakeup() at the appropriate time, otherwise we'll stall. - use DMA engine helper functions for type safety. - fix init when built as a module - we can't have to initcall functions, so we must settle on one. This means we can eliminate the deferred DMA initialization. - there is no need to terminate transfers on a failed prep_slave_sg() call - nothing has been setup, so nothing needs to be terminated. This avoids a potential deadlock in the DMA engine code (tasklet->callback->failed prepare->terminate->tasklet_disable which then ends up waiting for the tasklet to finish running.) - Dan says that the submission callback should not return an error: | dma_submit_error() is something I should have removed after commit | a0587bcf "ioat1: move descriptor allocation from submit to prep" all | errors should be notified by prep failing to return a descriptor | handle. Negative dma_cookie_t values are only returned by the | dma_async_memcpy* calls which translate a prep failure into -ENOMEM. So remove the error handling at that point. This also solves the potential deadlock mentioned in the previous comment. Acked-by: Linus Walleij Signed-off-by: Russell King

ARM: PL011: Ensure IRQs are disabled in UART interrupt handler

2011-01-05T16:58:47+00:00

As the DMA support introduces a separate interrupt-time callback, our interrupt handler will not be the only handler which takes the port lock, so we need to ensure that IRQs are disabled. We must use the _irqsave variant so we don't inadvertently enable interrupts. Acked-by: Linus Walleij Signed-off-by: Russell King

ARM: PL011: Separate hardware FIFO size from TTY FIFO size

2011-01-05T16:58:45+00:00

With DMA support, we need to tell the TTY subsystem that the DMA buffer is the size of the FIFO, otherwise things like tty_wait_until_sent() will time out too early. Keep (and use) the hardware value separately from the port->fifosize. This was part of a larger patch from Linus Walleij, with a little modification. Acked-by: Linus Walleij Signed-off-by: Russell King

ARM: PL011: Allow better handling of vendor data

2011-01-05T16:58:44+00:00

Rather than copying all vendor data into the port structure, copy just that which is frequently used, and keep a pointer to the remaining vendor data structure. This makes it easier to add vendor quirks in the future. Acked-by: Linus Walleij Signed-off-by: Russell King

ARM: PL011: Ensure error flags are clear at startup

2011-01-05T16:58:42+00:00

The error flags weren't being cleared upon UART startup, which can cause problems when we add DMA support. It's good practice to ensure that these flags are cleared anyway, so let's do so. This was part of a larger patch from Linus Walleij. Acked-by: Linus Walleij Signed-off-by: Russell King

ARM: PL011: include revision number in boot-time port printk

2011-01-05T16:58:36+00:00

Include the revision number of the PL011 primecell in the boot-time port printk to allow proper identification of the peripheral. Acked-by: Linus Walleij Signed-off-by: Russell King

ARM: Fix section build warnings for AMBA drivers

2010-07-27T09:48:43+00:00

Found in the Versatile build: WARNING: drivers/built-in.o(.data+0x14c): Section mismatch in reference from the variable pl061_gpio_driver to the (unknown reference) .init.data:(unknown) The variable pl061_gpio_driver references the (unknown reference) __initdata (unknown) WARNING: drivers/built-in.o(.data+0x40f8): Section mismatch in reference from the variable pl011_driver to the (unknown reference) .init.data:(unknown) The variable pl011_driver references the (unknown reference) __initdata (unknown) WARNING: drivers/built-in.o(.data+0x5ab4): Section mismatch in reference from the variable pl031_driver to the (unknown reference) .init.data:(unknown) The variable pl031_driver references the (unknown reference) __initdata (unknown) Basically, amba_id structures must not be __initdata. Also fix: WARNING: drivers/built-in.o(.data+0x138): Section mismatch in reference from the variable pl061_gpio_driver to the function .init.text:pl061_probe() The variable pl061_gpio_driver references the function __init pl061_probe() which is an incorrectly annotated probe function. Fix it to reflect the other AMBA bus probe functions by removing the __init attributation. Signed-off-by: Russell King

ARM: 6158/2: PL011 baudrate extension for ST-Ericssons derivative

2010-07-27T09:43:47+00:00

Implementation of the ST-Ericsson baudrate extension in the PL011 block. In this modified variant it is possible to change the sampling factor from 16 to 8, and thanks to this we can get higher baudrates while still using the same peripheral clock. Also replace the simple division to determine the baud divisor with DIV_ROUND_CLOSEST() rather than a simple integer division. Cc: Alessandro Rubini Cc: Jerzy Kasenberg Signed-off-by: Marcin Mielczarczyk Signed-off-by: Linus Walleij Signed-off-by: Russell King