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a6593c5c50
The x86-android-tablets code needs to be able to get a serdev_controller device from a PCI parent, rather then by the ACPI HID+UID of the parent, because on some tablets the UARTs are enumerated as PCI devices instead of ACPI devices. Split the code to walk the device hierarchy to find the serdev_controller from its parents out into a get_serdev_controller_from_parent() helper so that the x86-android-tablets code can re-use it. Reviewed-by: Andy Shevchenko <andy@kernel.org> Signed-off-by: Hans de Goede <hdegoede@redhat.com> Link: https://lore.kernel.org/r/20241204204227.95757-5-hdegoede@redhat.com Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
88 lines
2.6 KiB
C
88 lines
2.6 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* In some cases UART attached devices which require an in kernel driver,
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* e.g. UART attached Bluetooth HCIs are described in the ACPI tables
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* by an ACPI device with a broken or missing UartSerialBusV2() resource.
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*
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* This causes the kernel to create a /dev/ttyS# char-device for the UART
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* instead of creating an in kernel serdev-controller + serdev-device pair
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* for the in kernel driver.
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*
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* The quirk handling in acpi_quirk_skip_serdev_enumeration() makes the kernel
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* create a serdev-controller device for these UARTs instead of a /dev/ttyS#.
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*
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* Instantiating the actual serdev-device to bind to is up to pdx86 code,
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* this header provides a helper for getting the serdev-controller device.
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*/
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#include <linux/acpi.h>
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#include <linux/device.h>
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#include <linux/err.h>
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#include <linux/printk.h>
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#include <linux/sprintf.h>
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#include <linux/string.h>
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static inline struct device *
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get_serdev_controller_from_parent(struct device *ctrl_dev,
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int serial_ctrl_port,
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const char *serdev_ctrl_name)
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{
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struct device *child;
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char name[32];
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int i;
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/* Walk host -> uart-ctrl -> port -> serdev-ctrl */
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for (i = 0; i < 3; i++) {
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switch (i) {
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case 0:
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snprintf(name, sizeof(name), "%s:0", dev_name(ctrl_dev));
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break;
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case 1:
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snprintf(name, sizeof(name), "%s.%d",
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dev_name(ctrl_dev), serial_ctrl_port);
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break;
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case 2:
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strscpy(name, serdev_ctrl_name, sizeof(name));
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break;
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}
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child = device_find_child_by_name(ctrl_dev, name);
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put_device(ctrl_dev);
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if (!child) {
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pr_err("error could not find '%s' device\n", name);
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return ERR_PTR(-ENODEV);
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}
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ctrl_dev = child;
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}
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return ctrl_dev;
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}
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static inline struct device *
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get_serdev_controller(const char *serial_ctrl_hid,
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const char *serial_ctrl_uid,
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int serial_ctrl_port,
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const char *serdev_ctrl_name)
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{
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struct acpi_device *adev;
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struct device *parent;
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adev = acpi_dev_get_first_match_dev(serial_ctrl_hid, serial_ctrl_uid, -1);
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if (!adev) {
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pr_err("error could not get %s/%s serial-ctrl adev\n",
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serial_ctrl_hid, serial_ctrl_uid ?: "*");
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return ERR_PTR(-ENODEV);
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}
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/* get_first_physical_node() returns a weak ref */
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parent = get_device(acpi_get_first_physical_node(adev));
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acpi_dev_put(adev);
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if (!parent) {
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pr_err("error could not get %s/%s serial-ctrl physical node\n",
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serial_ctrl_hid, serial_ctrl_uid ?: "*");
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return ERR_PTR(-ENODEV);
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}
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/* This puts our reference on parent and returns a ref on the ctrl */
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return get_serdev_controller_from_parent(parent, serial_ctrl_port, serdev_ctrl_name);
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}
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