diff options
| author | Lukas Wunner <lukas@wunner.de> | 2020-05-18 16:45:02 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-05-29 12:42:54 +0200 |
| commit | d58a2df3d8877b91ecbfb936a15da364251a228f (patch) | |
| tree | 3d4552397dddb3809888ba9094415ae7eac46239 /drivers/tty/serial/8250 | |
| parent | f40a6be4a4e4985aef5365007e2459d757f26bdd (diff) | |
serial: 8250: Support rs485 bus termination GPIO
Commit e8759ad17d41 ("serial: uapi: Add support for bus termination")
introduced the ability to enable rs485 bus termination from user space.
So far the feature is only used by a single driver, 8250_exar.c, using a
hardcoded GPIO pin specific to Siemens IOT2040 products.
Provide for a more generic solution by allowing specification of an
rs485 bus termination GPIO pin in the device tree: Amend the serial
core to retrieve the GPIO from the device tree (or ACPI table) and amend
the default ->rs485_config() callback for 8250 drivers to change the
GPIO on request from user space.
Perhaps 8250_exar.c can be converted to the generic approach in a
follow-up patch.
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Jan Kiszka <jan.kiszka@siemens.com>
Link: https://lore.kernel.org/r/94c6c800d1ca9fa04766dd1d43a8272c5ad4bedd.1589811297.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/serial/8250')
| -rw-r--r-- | drivers/tty/serial/8250/8250_port.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c index bf2722e5e3aa..1632f7d25acc 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -681,6 +681,9 @@ int serial8250_em485_config(struct uart_port *port, struct serial_rs485 *rs485) memset(rs485->padding, 0, sizeof(rs485->padding)); port->rs485 = *rs485; + gpiod_set_value(port->rs485_term_gpio, + rs485->flags & SER_RS485_TERMINATE_BUS); + /* * Both serial8250_em485_init() and serial8250_em485_destroy() * are idempotent. |