1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Test driver for GNSS. This driver requires the serdev binding and protocol
4 * type to be specified on the module command line.
5 *
6 * Copyright 2019 Google LLC
7 */
8
9 #include <linux/device.h>
10 #include <linux/gnss.h>
11 #include <linux/module.h>
12 #include <linux/platform_device.h>
13 #include <linux/serdev.h>
14 #include <linux/slab.h>
15 #include <linux/string.h>
16
17 #include "serial.h"
18
19 #define GNSS_CMDLINE_MODULE_NAME "gnss-cmdline"
20
21 #define gnss_cmdline_err(...) \
22 pr_err(GNSS_CMDLINE_MODULE_NAME ": " __VA_ARGS__)
23
24 static char *serdev;
25 module_param(serdev, charp, 0644);
26 MODULE_PARM_DESC(serdev, "serial device to wrap");
27
28 static int type;
29 module_param(type, int, 0644);
30 MODULE_PARM_DESC(serdev, "GNSS protocol type (see 'enum gnss_type')");
31
32 static struct serdev_device *serdev_device;
33
name_match(struct device * dev,void * data)34 static int name_match(struct device *dev, void *data)
35 {
36 return strstr(dev_name(dev), data) != NULL;
37 }
38
gnss_cmdline_init(void)39 static int __init gnss_cmdline_init(void)
40 {
41 struct device *serial_dev, *port_dev, *serdev_dev;
42 char *driver_name, *port_name, *serdev_name;
43 char *serdev_dup, *serdev_dup_sep;
44 struct gnss_serial *gserial;
45 int err = -ENODEV;
46
47 /* User did not set the serdev module parameter */
48 if (!serdev)
49 return 0;
50
51 if (type < 0 || type >= GNSS_TYPE_COUNT) {
52 gnss_cmdline_err("invalid gnss type '%d'\n", type);
53 return -EINVAL;
54 }
55
56 serdev_dup = serdev_dup_sep = kstrdup(serdev, GFP_KERNEL);
57 if (!serdev_dup)
58 return -ENOMEM;
59
60 driver_name = strsep(&serdev_dup_sep, "/");
61 if (!driver_name) {
62 gnss_cmdline_err("driver name missing\n");
63 goto err_free_serdev_dup;
64 }
65
66 port_name = strsep(&serdev_dup_sep, "/");
67 if (!port_name) {
68 gnss_cmdline_err("port name missing\n");
69 goto err_free_serdev_dup;
70 }
71
72 serdev_name = strsep(&serdev_dup_sep, "/");
73 if (!serdev_name) {
74 gnss_cmdline_err("serdev name missing\n");
75 goto err_free_serdev_dup;
76 }
77
78 /* Find the driver device instance (e.g. serial8250) */
79 serial_dev = bus_find_device_by_name(&platform_bus_type,
80 NULL, driver_name);
81 if (!serial_dev) {
82 gnss_cmdline_err("no device '%s'\n", driver_name);
83 goto err_free_serdev_dup;
84 }
85
86 /* Find the port device instance (e.g. serial0) */
87 port_dev = device_find_child(serial_dev, port_name, name_match);
88 if (!port_dev) {
89 gnss_cmdline_err("no port '%s'\n", port_name);
90 goto err_free_serdev_dup;
91 }
92
93 /* Find the serdev device instance (e.g. serial0-0) */
94 serdev_dev = device_find_child(port_dev, serdev_name, name_match);
95 if (!serdev_dev) {
96 gnss_cmdline_err("no serdev '%s'\n", serdev_name);
97 goto err_free_serdev_dup;
98 }
99
100 gserial = gnss_serial_allocate(to_serdev_device(serdev_dev), 0);
101 if (IS_ERR(gserial)) {
102 err = PTR_ERR(gserial);
103 goto err_free_serdev_dup;
104 }
105
106 gserial->gdev->type = type;
107
108 err = gnss_serial_register(gserial);
109 if (err) {
110 gnss_serial_free(gserial);
111 goto err_free_serdev_dup;
112 }
113
114 serdev_device = to_serdev_device(serdev_dev);
115 err = 0;
116 err_free_serdev_dup:
117 kfree(serdev_dup);
118 return err;
119 }
120
gnss_cmdline_exit(void)121 static void __exit gnss_cmdline_exit(void)
122 {
123 struct gnss_serial *gserial;
124
125 if (!serdev_device)
126 return;
127
128 gserial = serdev_device_get_drvdata(serdev_device);
129
130 gnss_serial_deregister(gserial);
131 gnss_serial_free(gserial);
132 }
133
134 module_init(gnss_cmdline_init);
135 module_exit(gnss_cmdline_exit);
136
137 MODULE_AUTHOR("Alistair Delva <adelva@google.com>");
138 MODULE_DESCRIPTION("GNSS command line driver");
139 MODULE_LICENSE("GPL v2");
140