cmdline.c
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// SPDX-License-Identifier: GPL-2.0
/*
* Test driver for GNSS. This driver requires the serdev binding and protocol
* type to be specified on the module command line.
*
* Copyright 2019 Google LLC
*/
#include <linux/device.h>
#include <linux/gnss.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/serdev.h>
#include <linux/slab.h>
#include <linux/string.h>
#include "serial.h"
#define GNSS_CMDLINE_MODULE_NAME "gnss-cmdline"
#define gnss_cmdline_err(...) \
pr_err(GNSS_CMDLINE_MODULE_NAME ": " __VA_ARGS__)
static char *serdev;
module_param(serdev, charp, 0644);
MODULE_PARM_DESC(serdev, "serial device to wrap");
static int type;
module_param(type, int, 0644);
MODULE_PARM_DESC(serdev, "GNSS protocol type (see 'enum gnss_type')");
static struct serdev_device *serdev_device;
static int name_match(struct device *dev, void *data)
{
return strstr(dev_name(dev), data) != NULL;
}
static int __init gnss_cmdline_init(void)
{
struct device *serial_dev, *port_dev, *serdev_dev;
char *driver_name, *port_name, *serdev_name;
char *serdev_dup, *serdev_dup_sep;
struct gnss_serial *gserial;
int err = -ENODEV;
/* User did not set the serdev module parameter */
if (!serdev)
return 0;
if (type < 0 || type >= GNSS_TYPE_COUNT) {
gnss_cmdline_err("invalid gnss type '%d'\n", type);
return -EINVAL;
}
serdev_dup = serdev_dup_sep = kstrdup(serdev, GFP_KERNEL);
if (!serdev_dup)
return -ENOMEM;
driver_name = strsep(&serdev_dup_sep, "/");
if (!driver_name) {
gnss_cmdline_err("driver name missing\n");
goto err_free_serdev_dup;
}
port_name = strsep(&serdev_dup_sep, "/");
if (!port_name) {
gnss_cmdline_err("port name missing\n");
goto err_free_serdev_dup;
}
serdev_name = strsep(&serdev_dup_sep, "/");
if (!serdev_name) {
gnss_cmdline_err("serdev name missing\n");
goto err_free_serdev_dup;
}
/* Find the driver device instance (e.g. serial8250) */
serial_dev = bus_find_device_by_name(&platform_bus_type,
NULL, driver_name);
if (!serial_dev) {
gnss_cmdline_err("no device '%s'\n", driver_name);
goto err_free_serdev_dup;
}
/* Find the port device instance (e.g. serial0) */
port_dev = device_find_child(serial_dev, port_name, name_match);
if (!port_dev) {
gnss_cmdline_err("no port '%s'\n", port_name);
goto err_free_serdev_dup;
}
/* Find the serdev device instance (e.g. serial0-0) */
serdev_dev = device_find_child(port_dev, serdev_name, name_match);
if (!serdev_dev) {
gnss_cmdline_err("no serdev '%s'\n", serdev_name);
goto err_free_serdev_dup;
}
gserial = gnss_serial_allocate(to_serdev_device(serdev_dev), 0);
if (IS_ERR(gserial)) {
err = PTR_ERR(gserial);
goto err_free_serdev_dup;
}
gserial->gdev->type = type;
err = gnss_serial_register(gserial);
if (err) {
gnss_serial_free(gserial);
goto err_free_serdev_dup;
}
serdev_device = to_serdev_device(serdev_dev);
err = 0;
err_free_serdev_dup:
kfree(serdev_dup);
return err;
}
static void __exit gnss_cmdline_exit(void)
{
struct gnss_serial *gserial;
if (!serdev_device)
return;
gserial = serdev_device_get_drvdata(serdev_device);
gnss_serial_deregister(gserial);
gnss_serial_free(gserial);
}
module_init(gnss_cmdline_init);
module_exit(gnss_cmdline_exit);
MODULE_AUTHOR("Alistair Delva <adelva@google.com>");
MODULE_DESCRIPTION("GNSS command line driver");
MODULE_LICENSE("GPL v2");