29cb7002e5
This driver enables the "takeover" of a serdev bus device by the GNSS
subsystem. It can be used to test the GNSS subsystem without needing to
write a specific hardware backend.
The new module supports the following parameters:
gnss_cmdline.serdev=driver/port/serdev
gnss_cmdline.type=<protocol number>
An example which allows GNSS to wrap a platform serial8250 port and
advertise NMEA-0183 data is:
gnss_cmdline.serdev=serial8250/serial0/serial0-0
^ ^ ^
driver port serdev
gnss_cmdline.type=0
^
GNSS_TYPE_NMEA
Bug: 146517987
Change-Id: I421386ee4f2ba8f1f0832d9c56a067a600892d3c
Signed-off-by: Alistair Delva <adelva@google.com>
139 lines
3.3 KiB
C
139 lines
3.3 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Test driver for GNSS. This driver requires the serdev binding and protocol
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* type to be specified on the module command line.
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*
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* Copyright 2019 Google LLC
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*/
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#include <linux/device.h>
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#include <linux/gnss.h>
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#include <linux/module.h>
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#include <linux/platform_device.h>
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#include <linux/serdev.h>
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#include <linux/slab.h>
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#include <linux/string.h>
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#include "serial.h"
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#define GNSS_CMDLINE_MODULE_NAME "gnss-cmdline"
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#define gnss_cmdline_err(...) \
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pr_err(GNSS_CMDLINE_MODULE_NAME ": " __VA_ARGS__)
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static char *serdev;
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module_param(serdev, charp, 0644);
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MODULE_PARM_DESC(serdev, "serial device to wrap");
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static int type;
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module_param(type, int, 0644);
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MODULE_PARM_DESC(serdev, "GNSS protocol type (see 'enum gnss_type')");
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static struct serdev_device *serdev_device;
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static int name_match(struct device *dev, void *data)
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{
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return strstr(dev_name(dev), data) != NULL;
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}
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static int __init gnss_cmdline_init(void)
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{
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struct device *serial_dev, *port_dev, *serdev_dev;
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char *driver_name, *port_name, *serdev_name;
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char *serdev_dup, *serdev_dup_sep;
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struct gnss_serial *gserial;
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int err = -ENODEV;
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/* User did not set the serdev module parameter */
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if (!serdev)
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return 0;
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if (type < 0 || type >= GNSS_TYPE_COUNT) {
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gnss_cmdline_err("invalid gnss type '%d'\n", type);
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return -EINVAL;
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}
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serdev_dup = serdev_dup_sep = kstrdup(serdev, GFP_KERNEL);
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if (!serdev_dup)
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return -ENOMEM;
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driver_name = strsep(&serdev_dup_sep, "/");
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if (!driver_name) {
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gnss_cmdline_err("driver name missing\n");
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goto err_free_serdev_dup;
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}
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port_name = strsep(&serdev_dup_sep, "/");
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if (!port_name) {
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gnss_cmdline_err("port name missing\n");
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goto err_free_serdev_dup;
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}
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serdev_name = strsep(&serdev_dup_sep, "/");
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if (!serdev_name) {
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gnss_cmdline_err("serdev name missing\n");
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goto err_free_serdev_dup;
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}
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/* Find the driver device instance (e.g. serial8250) */
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serial_dev = bus_find_device_by_name(&platform_bus_type,
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NULL, driver_name);
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if (!serial_dev) {
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gnss_cmdline_err("no device '%s'\n", driver_name);
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goto err_free_serdev_dup;
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}
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/* Find the port device instance (e.g. serial0) */
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port_dev = device_find_child(serial_dev, port_name, name_match);
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if (!port_dev) {
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gnss_cmdline_err("no port '%s'\n", port_name);
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goto err_free_serdev_dup;
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}
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/* Find the serdev device instance (e.g. serial0-0) */
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serdev_dev = device_find_child(port_dev, serdev_name, name_match);
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if (!serdev_dev) {
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gnss_cmdline_err("no serdev '%s'\n", serdev_name);
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goto err_free_serdev_dup;
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}
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gserial = gnss_serial_allocate(to_serdev_device(serdev_dev), 0);
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if (IS_ERR(gserial)) {
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err = PTR_ERR(gserial);
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goto err_free_serdev_dup;
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}
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gserial->gdev->type = type;
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err = gnss_serial_register(gserial);
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if (err) {
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gnss_serial_free(gserial);
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goto err_free_serdev_dup;
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}
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serdev_device = to_serdev_device(serdev_dev);
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err = 0;
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err_free_serdev_dup:
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kfree(serdev_dup);
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return err;
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}
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static void __exit gnss_cmdline_exit(void)
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{
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struct gnss_serial *gserial;
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if (!serdev_device)
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return;
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gserial = serdev_device_get_drvdata(serdev_device);
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gnss_serial_deregister(gserial);
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gnss_serial_free(gserial);
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}
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module_init(gnss_cmdline_init);
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module_exit(gnss_cmdline_exit);
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MODULE_AUTHOR("Alistair Delva <adelva@google.com>");
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MODULE_DESCRIPTION("GNSS command line driver");
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MODULE_LICENSE("GPL v2");
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