A break interrupt will be generated if the RX line was pulled low, which
means some abnomal behaviors occurred of the UART. In this case, we still
need to clear this break interrupt status, otherwise it will cause irq
storm to crash the whole system.

Fixes: b7396a38fb28 ("tty/serial: Add Spreadtrum sc9836-uart driver support")
Signed-off-by: Yonghan Ye <yonghan.ye@unisoc.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Baolin Wang <baolin.wang7@gmail.com>
Link: https://lore.kernel.org/r/925e51b73099c90158e080b8f5bed9b3b38c4548.1575460601.git.baolin.wang7@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

In order to access the UART without the interrupts, the kernel uses
the basic polling methods for IO with the device. With these methods
implemented, it is now possible to enable kgdb during early boot over serial.

Signed-off-by: Lanqing Liu <liuhhome@gmail.com>
Reviewed-by: Baolin Wang <baolin.wang@linaro.org>
Tested-by: Baolin Wang <baolin.wang@linaro.org>
Link: https://lore.kernel.org/r/f112a741c053ac5fb0637e2f058be81e17f78ccc.1568862391.git.liuhhome@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The sequence of arguments which was passed to handle_lsr_errors() didn't
match the parameters defined in that function, &lsr was passed to flag
and &flag was passed to lsr, this patch fixed that.

Fixes: b7396a38fb28 ("tty/serial: Add Spreadtrum sc9836-uart driver support")
Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com>
Signed-off-by: Chunyan Zhang <zhang.lyra@gmail.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20190905074151.5268-1-zhang.lyra@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The sprd serial console can work with only 26M fixed clock,
but the probe() is returning fail if the clock "enable" is not
configured in device tree.

This patch will fix the problem to let the uart device which is
used for console can be initialized even missing "enable" clock
configured in devicetree. We should make sure the debug function
as available as we can.

Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com>
Signed-off-by: Chunyan Zhang <zhang.lyra@gmail.com>
Reviewed-by: Baolin Wang <baolin.wang@linaro.org>
Tested-by: Baolin Wang <baolin.wang@linaro.org>
Link: https://lore.kernel.org/r/20190826072929.7696-4-zhang.lyra@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Use console_initcall to save the console index we selected on the
command line to sprd_console before probe finished. Thus we can
make different processes to the uart devices during initialization
according to whether it is used for console.

Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com>
Signed-off-by: Chunyan Zhang <zhang.lyra@gmail.com>
Reviewed-by: Baolin Wang <baolin.wang@linaro.org>
Tested-by: Baolin Wang <baolin.wang@linaro.org>
Link: https://lore.kernel.org/r/20190826072929.7696-3-zhang.lyra@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

When calling sprd_console_setup(), sprd_uart_port probably is NULL,
we should check that first instead of checking its items directly.

Also we should check membase to avoid accessing uart device before
its initialization finished.

Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com>
Signed-off-by: Chunyan Zhang <zhang.lyra@gmail.com>
Reviewed-by: Baolin Wang <baolin.wang@linaro.org>
Tested-by: Baolin Wang <baolin.wang@linaro.org>
Link: https://lore.kernel.org/r/20190826072929.7696-2-zhang.lyra@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Add loopback function support for Spreadtrum serial controller.

Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Link: https://lore.kernel.org/r/1275cd9968f1ceb5ac049cc23f1e508025cd552f.1566375260.git.baolin.wang@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

We don't need dev_err() messages when platform_get_irq() fails now that
platform_get_irq() prints an error message itself when something goes
wrong. Let's remove these prints with a simple semantic patch.

// <smpl>
@@
expression ret;
struct platform_device *E;
@@

ret =
(
platform_get_irq(E, ...)
|
platform_get_irq_byname(E, ...)
);

if ( \( ret < 0 \| ret <= 0 \) )
{
(
-if (ret != -EPROBE_DEFER)
-{ ...
-dev_err(...);
-... }
|
...
-dev_err(...);
)
...
}
// </smpl>

While we're here, remove braces on if statements that only have one
statement (manually).

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/20190730181557.90391-45-swboyd@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

when dma_request_chan rx_dma fails, dev_err log should print rx_dma
err log.

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Reviewed-by: Mukesh Ojha <mojha@codeaurora.org>
Reviewed-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Add DMA mode support for the Spreadtrum serial controller.

Signed-off-by: Lanqing Liu <lanqing.liu@unisoc.com>
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>