14 Commits

Author SHA1 Message Date
Evan Green
638a6f4ebe tty: serial: msm_geni_serial: Fix TX infinite loop
The GENI serial driver handled transmit by leaving stuff in the
common circular buffer until it had completely caught up to the head,
then clearing it out all at once. This is a suboptimal way to do
transmit, as it leaves data in the circular buffer that could be
freed. Moreover, the logic implementing it is wrong, and it is easy to
get into a situation where the UART infinitely writes out the same buffer.

I could reproduce infinite serial output of the same buffer by running
dmesg, then hitting Ctrl-C. I believe what happened is xmit_size was
something large, marching towards a larger value. Then the generic OS
code flushed out the buffer and replaced it with two characters. Now the
xmit_size is a large value marching towards a small value, which it wasn't
expecting. The driver subtracts xmit_size (very large) from
uart_circ_chars_pending (2), underflows, and repeats ad nauseum. The
locking isn't wrong here, as the locks are held whenever the buffer is
manipulated, it's just that the driver wasn't expecting the buffer to be
flushed out from underneath it in between transmits.

This change reworks transmit to grab what it can from the circular buffer,
and then update ->tail, both fixing the underflow and freeing up space
for a smoother circular experience.

Signed-off-by: Evan Green <evgreen@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-05-14 13:52:35 +02:00
Karthikeyan Ramasubramanian
43f1831b08 tty: serial: qcom_geni_serial: Add early console support
Add early console support in Qualcomm Technologies Inc., GENI based
UART controller.

Signed-off-by: Karthikeyan Ramasubramanian <kramasub@codeaurora.org>
Signed-off-by: Girish Mahadevan <girishm@codeaurora.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-05-14 13:44:55 +02:00
Karthikeyan Ramasubramanian
ec91df8d3f tty: serial: qcom_geni_serial: Return IRQ_NONE for spurious interrupts
Currently the driver returns IRQ_HANDLED when spurious interrupts happen.
This is misleading. Fix the behavior by returning IRQ_NONE for spurious
interrupts.

Signed-off-by: Karthikeyan Ramasubramanian <kramasub@codeaurora.org>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-05-14 13:44:55 +02:00
Karthikeyan Ramasubramanian
69736b57df tty: serial: qcom_geni_serial: Use iowrite32_rep to write to FIFO
Use iowrite32_rep to write to the hardware FIFO so that the code does
not have to worry about the system endianness.

Signed-off-by: Karthikeyan Ramasubramanian <kramasub@codeaurora.org>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-05-14 13:44:55 +02:00
Karthikeyan Ramasubramanian
7fb5b88001 tty: serial: qcom_geni_serial: Remove unnecessary memory barrier
While initiating TX, only the register reads need to be ordered. The
register write order either is achieved due to data dependency or is
not required.

Use readl to achieve the read order and remove the unnecessary barrier.

Signed-off-by: Karthikeyan Ramasubramanian <kramasub@codeaurora.org>
Reviewed-by: Evan Green <evgreen@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-05-14 13:44:55 +02:00
Karthikeyan Ramasubramanian
f737175061 tty: serial: qcom_geni_serial: Initialize console port statically
Perform static initialization of console_port since its initial state has
no run-time dependencies.

Signed-off-by: Karthikeyan Ramasubramanian <kramasub@codeaurora.org>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-05-14 13:44:55 +02:00
Karthikeyan Ramasubramanian
8e70c47c48 tty: serial: qcom_geni_serial: Use min3 to find minimum of 3 values
Use min3 helper to calculate the minimum value of 3 variables.

Signed-off-by: Karthikeyan Ramasubramanian <kramasub@codeaurora.org>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-05-14 13:44:55 +02:00
Karthikeyan Ramasubramanian
6a10635e90 tty: serial: qcom_geni_serial: Cleanup redundant code
* Remove redundant casting while using min_t
* Remove redundant initialization of port_setup flag
* Remove redundant error checking in get_tx_fifo_size
* Remove logging redundant error code in debug messages
* Remove redundant disable_irq before free_irq

Signed-off-by: Karthikeyan Ramasubramanian <kramasub@codeaurora.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-05-14 13:44:54 +02:00
Karthikeyan Ramasubramanian
f02625689e tty: serial: qcom_geni_serial: Add comments for clarification
* Document reason for newline character counting in console_write
* Document reason for disabling IRQ in the system resume operation

Signed-off-by: Karthikeyan Ramasubramanian <kramasub@codeaurora.org>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-05-14 13:44:54 +02:00
Greg Kroah-Hartman
7b6c81f46c Merge 4.17-rc3 into tty-next
We want the tty and serial driver fixes in here as well.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-04-30 05:14:55 -07:00
Karthikeyan Ramasubramanian
066cd1c4e4 tty: serial: qcom_geni_serial: Use signed variable to get IRQ
The platform_get_irq can return error. Assigning the return value to an
unsigned variable and checking it for negative value will always return
false.

Use an intermediate signed variable to get IRQ information, check for any
error and then assign it to 'irq' variable inside uart_port structure.

Signed-off-by: Karthikeyan Ramasubramanian <kramasub@codeaurora.org>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-04-23 10:22:30 +02:00
Wolfram Sang
a406c4b809 tty: serial: simplify getting .drvdata
We should get drvdata from struct device directly. Going via
platform_device is an unneeded step back and forth.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Michal Simek <michal.simek@xilinx.com>
Acked-by: Patrice Chotard <patrice.chotard@st.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-04-22 17:29:43 +02:00
Wei Yongjun
7693b331d0 tty: serial: msm_geni_serial: Fix return value check in qcom_geni_serial_probe()
In case of error, the function platform_get_resource() returns NULL
pointer not ERR_PTR(). The IS_ERR() test in the return value check
should be replaced with NULL test.

Fixes: c4f528795d1a ("tty: serial: msm_geni_serial: Add serial driver support for GENI based QUP")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-03-22 18:33:44 +01:00
Karthikeyan Ramasubramanian
c4f528795d tty: serial: msm_geni_serial: Add serial driver support for GENI based QUP
This driver supports GENI based UART Controller in the Qualcomm SOCs. The
Qualcomm Generic Interface (GENI) is a programmable module supporting a
wide range of serial interfaces including UART. This driver support console
operations using FIFO mode of transfer.

Signed-off-by: Girish Mahadevan <girishm@codeaurora.org>
Signed-off-by: Karthikeyan Ramasubramanian <kramasub@codeaurora.org>
Signed-off-by: Sagar Dharia <sdharia@codeaurora.org>
Signed-off-by: Doug Anderson <dianders@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-03-20 09:13:15 +01:00