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Commit 29cb7002 authored by Alistair Delva's avatar Alistair Delva
Browse files

ANDROID: gnss: Add command line test driver 



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: default avatarAlistair Delva <adelva@google.com>
parent 3c996ff8

drivers/gnss/Kconfig

+15 −0
Original line number Diff line number Diff line
@@ -40,4 +40,19 @@ config GNSS_UBX_SERIAL 


	  If unsure, say N.



config GNSS_CMDLINE_SERIAL

	tristate "Command line test driver for GNSS"

	depends on SERIAL_DEV_BUS

	select GNSS_SERIAL

	---help---

	  Say Y here if you want to test the GNSS subsystem but do not have a

	  way to communicate a binding through firmware such as DT or ACPI.

	  The correct serdev device and protocol type must be specified on

	  the module command line.



	  To compile this driver as a module, choose M here: the module will

	  be called gnss-cmdline.



	  If unsure, say N.



endif # GNSS

drivers/gnss/Makefile

+3 −0
Original line number Diff line number Diff line
@@ -14,3 +14,6 @@ gnss-sirf-y := sirf.o 


obj-$(CONFIG_GNSS_UBX_SERIAL)		+= gnss-ubx.o

gnss-ubx-y := ubx.o



obj-$(CONFIG_GNSS_CMDLINE_SERIAL)	+= gnss-cmdline.o

gnss-cmdline-y := cmdline.o

drivers/gnss/cmdline.c

0 → 100644
+139 −0
Original line number Diff line number Diff line 
// 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");