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authorLukas Wunner <lukas@wunner.de>2020-05-18 16:45:02 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2020-05-29 12:42:54 +0200
commitd58a2df3d8877b91ecbfb936a15da364251a228f (patch)
tree3d4552397dddb3809888ba9094415ae7eac46239 /Documentation/devicetree
parentf40a6be4a4e4985aef5365007e2459d757f26bdd (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>
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