1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* Copyright (c) 2021 IBM Corp. */
3 
4 #include <linux/delay.h>
5 #include <linux/device.h>
6 #include <linux/errno.h>
7 #include <linux/list.h>
8 #include <linux/module.h>
9 #include <linux/sched/signal.h>
10 #include <linux/serio.h>
11 #include <linux/slab.h>
12 
13 #include "kcs_bmc_client.h"
14 
15 struct kcs_bmc_serio {
16 	struct list_head entry;
17 
18 	struct kcs_bmc_client client;
19 	struct serio *port;
20 
21 	spinlock_t lock;
22 };
23 
24 static inline struct kcs_bmc_serio *client_to_kcs_bmc_serio(struct kcs_bmc_client *client)
25 {
26 	return container_of(client, struct kcs_bmc_serio, client);
27 }
28 
29 static irqreturn_t kcs_bmc_serio_event(struct kcs_bmc_client *client)
30 {
31 	struct kcs_bmc_serio *priv;
32 	u8 handled = IRQ_NONE;
33 	u8 status;
34 
35 	priv = client_to_kcs_bmc_serio(client);
36 
37 	spin_lock(&priv->lock);
38 
39 	status = kcs_bmc_read_status(client->dev);
40 
41 	if (status & KCS_BMC_STR_IBF)
42 		handled = serio_interrupt(priv->port, kcs_bmc_read_data(client->dev), 0);
43 
44 	spin_unlock(&priv->lock);
45 
46 	return handled;
47 }
48 
49 static const struct kcs_bmc_client_ops kcs_bmc_serio_client_ops = {
50 	.event = kcs_bmc_serio_event,
51 };
52 
53 static int kcs_bmc_serio_open(struct serio *port)
54 {
55 	struct kcs_bmc_serio *priv = port->port_data;
56 
57 	return kcs_bmc_enable_device(priv->client.dev, &priv->client);
58 }
59 
60 static void kcs_bmc_serio_close(struct serio *port)
61 {
62 	struct kcs_bmc_serio *priv = port->port_data;
63 
64 	kcs_bmc_disable_device(priv->client.dev, &priv->client);
65 }
66 
67 static DEFINE_SPINLOCK(kcs_bmc_serio_instances_lock);
68 static LIST_HEAD(kcs_bmc_serio_instances);
69 
70 static int kcs_bmc_serio_add_device(struct kcs_bmc_device *kcs_bmc)
71 {
72 	struct kcs_bmc_serio *priv;
73 	struct serio *port;
74 
75 	priv = devm_kzalloc(kcs_bmc->dev, sizeof(*priv), GFP_KERNEL);
76 	if (!priv)
77 		return -ENOMEM;
78 
79 	/* Use kzalloc() as the allocation is cleaned up with kfree() via serio_unregister_port() */
80 	port = kzalloc(sizeof(*port), GFP_KERNEL);
81 	if (!port)
82 		return -ENOMEM;
83 
84 	port->id.type = SERIO_8042;
85 	port->open = kcs_bmc_serio_open;
86 	port->close = kcs_bmc_serio_close;
87 	port->port_data = priv;
88 	port->dev.parent = kcs_bmc->dev;
89 
90 	spin_lock_init(&priv->lock);
91 	priv->port = port;
92 	priv->client.dev = kcs_bmc;
93 	priv->client.ops = &kcs_bmc_serio_client_ops;
94 
95 	spin_lock_irq(&kcs_bmc_serio_instances_lock);
96 	list_add(&priv->entry, &kcs_bmc_serio_instances);
97 	spin_unlock_irq(&kcs_bmc_serio_instances_lock);
98 
99 	serio_register_port(port);
100 
101 	dev_info(kcs_bmc->dev, "Initialised serio client for channel %d", kcs_bmc->channel);
102 
103 	return 0;
104 }
105 
106 static int kcs_bmc_serio_remove_device(struct kcs_bmc_device *kcs_bmc)
107 {
108 	struct kcs_bmc_serio *priv = NULL, *pos;
109 
110 	spin_lock_irq(&kcs_bmc_serio_instances_lock);
111 	list_for_each_entry(pos, &kcs_bmc_serio_instances, entry) {
112 		if (pos->client.dev == kcs_bmc) {
113 			priv = pos;
114 			list_del(&pos->entry);
115 			break;
116 		}
117 	}
118 	spin_unlock_irq(&kcs_bmc_serio_instances_lock);
119 
120 	if (!priv)
121 		return -ENODEV;
122 
123 	/* kfree()s priv->port via put_device() */
124 	serio_unregister_port(priv->port);
125 
126 	/* Ensure the IBF IRQ is disabled if we were the active client */
127 	kcs_bmc_disable_device(kcs_bmc, &priv->client);
128 
129 	devm_kfree(priv->client.dev->dev, priv);
130 
131 	return 0;
132 }
133 
134 static const struct kcs_bmc_driver_ops kcs_bmc_serio_driver_ops = {
135 	.add_device = kcs_bmc_serio_add_device,
136 	.remove_device = kcs_bmc_serio_remove_device,
137 };
138 
139 static struct kcs_bmc_driver kcs_bmc_serio_driver = {
140 	.ops = &kcs_bmc_serio_driver_ops,
141 };
142 
143 static int __init kcs_bmc_serio_init(void)
144 {
145 	kcs_bmc_register_driver(&kcs_bmc_serio_driver);
146 
147 	return 0;
148 }
149 module_init(kcs_bmc_serio_init);
150 
151 static void __exit kcs_bmc_serio_exit(void)
152 {
153 	kcs_bmc_unregister_driver(&kcs_bmc_serio_driver);
154 }
155 module_exit(kcs_bmc_serio_exit);
156 
157 MODULE_LICENSE("GPL v2");
158 MODULE_AUTHOR("Andrew Jeffery <andrew@aj.id.au>");
159 MODULE_DESCRIPTION("Adapter driver for serio access to BMC KCS devices");
160