If a RX_DURING_TX GPIO is defined by the DT property "rs485-rx-during-tx-gpios"
this patch switches this GPIO accordingly to the RS485 flag RX_DURING_TX in user
space. In addition, the i.MX UART receiver is no longer turned on and off during
sending, because now the hardware is responsible for connecting or disconnecting
RX during TX controlled by this GPIO.
Signed-off-by: Christoph Niedermaier <cniedermaier@dh-electronics.com>
Link: https://lore.kernel.org/r/20221202104127.122761-3-cniedermaier@dh-electronics.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add a binding for a generic definition of an output GPIO that sets the
state of rs485-rx-during-tx. The idea is that the hardware already controls
the option receiving during sending before it gets to the signal receiving
hardware. The standard RS485 is a half-duplex bus that in most cases is
driven by an UART controller. The advantage of using this GPIO is that it
is independent of the capabilities of the UART core and the UART driver.
On the hardware side the interface to the bus is controlled by a transceiver,
that has a pin called RE (RX Enable) or similar, which connects the bus to
the RX signal of the UART controller. The GPIO can switch between two states
to control the RE pin via an electrical circuit:
- Active:
The RE pin is always active. The UART RX see everything on the bus and
therefore also what happens with the TX signal on the bus.
- Inactive:
The RE pin is always active, but during sending on the bus the pin RE is
inactive. So basically the receiving during sending is suppressed.
A possible circuit diagram could look like this:
┌──────────────────┐
│ RS485 │
TX ───────────────┤D │
│ Transceiver │
RTS ────┬──────────┤DE │
│ │ │
│ ┌─────┐ │ │
└─┤& │ │ │
│ ├──┤!RE │
!rx_during_tx_gpio ──────┤ │ │ │
└─────┘ │ │
│ │
RX ───────────────┤R │
│ │
└──────────────────┘
Here the RTS pin of the UART core is used to control TX via the transceiver
pin DE (Drive Enable). RE and rx_during_tx_gpio are active low.
Signed-off-by: Christoph Niedermaier <cniedermaier@dh-electronics.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20221202104127.122761-1-cniedermaier@dh-electronics.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add the missing clk_disable_unprepare() before return from
tegra_uart_hw_init() in the error handling path.
When request_irq() fails in tegra_uart_startup(), 'tup->uart_clk'
has been enabled, fix it by adding clk_disable_unprepare().
Fixes: cc9ca4d958 ("serial: tegra: Only print FIFO error message when an error occurs")
Fixes: d781ec21ba ("serial: tegra: report clk rate errors")
Signed-off-by: Yi Yang <yiyang13@huawei.com>
Link: https://lore.kernel.org/r/20221126020852.113378-1-yiyang13@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The GPIO controller component of the sc16is7xx driver is setup too
early, which can result in a race condition where another device tries
to utilise the GPIO lines before the sc16is7xx device has finished
initialising.
This issue manifests itself as an Oops when the GPIO lines are configured:
Unable to handle kernel read from unreadable memory at virtual address
...
pc : sc16is7xx_gpio_direction_output+0x68/0x108 [sc16is7xx]
lr : sc16is7xx_gpio_direction_output+0x4c/0x108 [sc16is7xx]
...
Call trace:
sc16is7xx_gpio_direction_output+0x68/0x108 [sc16is7xx]
gpiod_direction_output_raw_commit+0x64/0x318
gpiod_direction_output+0xb0/0x170
create_gpio_led+0xec/0x198
gpio_led_probe+0x16c/0x4f0
platform_drv_probe+0x5c/0xb0
really_probe+0xe8/0x448
driver_probe_device+0xe8/0x138
__device_attach_driver+0x94/0x118
bus_for_each_drv+0x8c/0xe0
__device_attach+0x100/0x1b8
device_initial_probe+0x28/0x38
bus_probe_device+0xa4/0xb0
deferred_probe_work_func+0x90/0xe0
process_one_work+0x1c4/0x480
worker_thread+0x54/0x430
kthread+0x138/0x150
ret_from_fork+0x10/0x1c
This patch moves the setup of the GPIO controller functions to later in the
probe function, ensuring the sc16is7xx device has already finished
initialising by the time other devices try to make use of the GPIO lines.
The error handling has also been reordered to reflect the new
initialisation order.
Co-developed-by: Wen-chien Jesse Sung <jesse.sung@canonical.com>
Signed-off-by: Wen-chien Jesse Sung <jesse.sung@canonical.com>
Signed-off-by: Isaac True <isaac.true@canonical.com>
Link: https://lore.kernel.org/r/20221130105529.698385-1-isaac.true@canonical.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The algorithm used for scrolling is the array juggling. It has
complexity O(N) and space complexity O(1). I.e. quite fast w/o
requirements for temporary storage.
Move the algorithm to a separate function so it is obvious what it is.
It is almost generic (except the array type), so if anyone else wants
array rotation, feel free to make it generic and move it to include/.
And rename all the variables from i, j, k, sz, d, and so on to something
saner.
Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20230112080136.4929-9-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
No need to panic in vc_uniscr_copy_line(), just warn. This should never
happen though, as vc_uniscr_check() is supposed to be called before
vc_uniscr_copy_line(). And the former checks vc->vc_uni_lines already.
In any case, use _ONCE as vc_uniscr_copy_line() is called repeatedly for
each line. So don't flood the logs, just in case.
Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20230112080136.4929-7-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
LPUART IP has a bug that it treats the CTS as higher priority than the
break signal, which cause the break signal sending through UARTCTRL_SBK
may impacted by the CTS input if the HW flow control is enabled.
Add this workaround patch to fix the IP bug, we can disable CTS before
asserting SBK to avoid any interference from CTS, and re-enable it when
break off.
Such as for the bluetooth chip power save feature, host can let the BT
chip get into sleep state by sending a UART break signal, and wake it up
by turning off the UART break. If the BT chip enters the sleep mode
successfully, it will pull up the CTS line, if the BT chip is woken up,
it will pull down the CTS line. If without this workaround patch, the
UART TX pin cannot send the break signal successfully as it affected by
the BT CTS pin. After adding this patch, the BT power save feature can
work well.
Signed-off-by: Sherry Sun <sherry.sun@nxp.com>
Link: https://lore.kernel.org/r/20221214031137.28815-2-sherry.sun@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
UARTBAUD_RDMAE and UARTBAUD_TDMAE are enabled in lpuart32_startup(), but
lpuart32_shutdown() not disable them, only free the dma ring buffer and
release the dma channels, so here disable the Rx/Tx DMA first in
lpuart32_shutdown().
Fixes: 42b68768e5 ("serial: fsl_lpuart: DMA support for 32-bit variant")
Signed-off-by: Sherry Sun <sherry.sun@nxp.com>
Link: https://lore.kernel.org/r/20221125101953.18753-3-sherry.sun@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
For the lpuart driver, the Idle Line Interrupt Enable now is only needed
for the CPU mode, so enable the UARTCTRL_ILIE at the correct place, and
clear it when shutdown.
Also need to configure the suitable UARTCTRL_IDLECFG, now the value is
0x7, represent 128 idle characters will trigger the Idle Line Interrupt.
Signed-off-by: Sherry Sun <sherry.sun@nxp.com>
Link: https://lore.kernel.org/r/20221125101953.18753-2-sherry.sun@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
