char/ipmi/kcs_bmc_serio.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /* Copyright (c) 2021 IBM Corp. */
0003
0004 #include <linux/delay.h>
0005 #include <linux/device.h>
0006 #include <linux/errno.h>
0007 #include <linux/list.h>
0008 #include <linux/module.h>
0009 #include <linux/sched/signal.h>
0010 #include <linux/serio.h>
0011 #include <linux/slab.h>
0012
0013 #include "kcs_bmc_client.h"
0014
0015 struct kcs_bmc_serio {
0016     struct list_head entry;
0017
0018     struct kcs_bmc_client client;
0019     struct serio *port;
0020
0021     spinlock_t lock;
0022 };
0023
0024 static inline struct kcs_bmc_serio *client_to_kcs_bmc_serio(struct kcs_bmc_client *client)
0025 {
0026     return container_of(client, struct kcs_bmc_serio, client);
0027 }
0028
0029 static irqreturn_t kcs_bmc_serio_event(struct kcs_bmc_client *client)
0030 {
0031     struct kcs_bmc_serio *priv;
0032     u8 handled = IRQ_NONE;
0033     u8 status;
0034
0035     priv = client_to_kcs_bmc_serio(client);
0036
0037     spin_lock(&priv->lock);
0038
0039     status = kcs_bmc_read_status(client->dev);
0040
0041     if (status & KCS_BMC_STR_IBF)
0042         handled = serio_interrupt(priv->port, kcs_bmc_read_data(client->dev), 0);
0043
0044     spin_unlock(&priv->lock);
0045
0046     return handled;
0047 }
0048
0049 static const struct kcs_bmc_client_ops kcs_bmc_serio_client_ops = {
0050     .event = kcs_bmc_serio_event,
0051 };
0052
0053 static int kcs_bmc_serio_open(struct serio *port)
0054 {
0055     struct kcs_bmc_serio *priv = port->port_data;
0056
0057     return kcs_bmc_enable_device(priv->client.dev, &priv->client);
0058 }
0059
0060 static void kcs_bmc_serio_close(struct serio *port)
0061 {
0062     struct kcs_bmc_serio *priv = port->port_data;
0063
0064     kcs_bmc_disable_device(priv->client.dev, &priv->client);
0065 }
0066
0067 static DEFINE_SPINLOCK(kcs_bmc_serio_instances_lock);
0068 static LIST_HEAD(kcs_bmc_serio_instances);
0069
0070 static int kcs_bmc_serio_add_device(struct kcs_bmc_device *kcs_bmc)
0071 {
0072     struct kcs_bmc_serio *priv;
0073     struct serio *port;
0074
0075     priv = devm_kzalloc(kcs_bmc->dev, sizeof(*priv), GFP_KERNEL);
0076     if (!priv)
0077         return -ENOMEM;
0078
0079     /* Use kzalloc() as the allocation is cleaned up with kfree() via serio_unregister_port() */
0080     port = kzalloc(sizeof(*port), GFP_KERNEL);
0081     if (!port)
0082         return -ENOMEM;
0083
0084     port->id.type = SERIO_8042;
0085     port->open = kcs_bmc_serio_open;
0086     port->close = kcs_bmc_serio_close;
0087     port->port_data = priv;
0088     port->dev.parent = kcs_bmc->dev;
0089
0090     spin_lock_init(&priv->lock);
0091     priv->port = port;
0092     priv->client.dev = kcs_bmc;
0093     priv->client.ops = &kcs_bmc_serio_client_ops;
0094
0095     spin_lock_irq(&kcs_bmc_serio_instances_lock);
0096     list_add(&priv->entry, &kcs_bmc_serio_instances);
0097     spin_unlock_irq(&kcs_bmc_serio_instances_lock);
0098
0099     serio_register_port(port);
0100
0101     dev_info(kcs_bmc->dev, "Initialised serio client for channel %d", kcs_bmc->channel);
0102
0103     return 0;
0104 }
0105
0106 static int kcs_bmc_serio_remove_device(struct kcs_bmc_device *kcs_bmc)
0107 {
0108     struct kcs_bmc_serio *priv = NULL, *pos;
0109
0110     spin_lock_irq(&kcs_bmc_serio_instances_lock);
0111     list_for_each_entry(pos, &kcs_bmc_serio_instances, entry) {
0112         if (pos->client.dev == kcs_bmc) {
0113             priv = pos;
0114             list_del(&pos->entry);
0115             break;
0116         }
0117     }
0118     spin_unlock_irq(&kcs_bmc_serio_instances_lock);
0119
0120     if (!priv)
0121         return -ENODEV;
0122
0123     /* kfree()s priv->port via put_device() */
0124     serio_unregister_port(priv->port);
0125
0126     /* Ensure the IBF IRQ is disabled if we were the active client */
0127     kcs_bmc_disable_device(kcs_bmc, &priv->client);
0128
0129     devm_kfree(priv->client.dev->dev, priv);
0130
0131     return 0;
0132 }
0133
0134 static const struct kcs_bmc_driver_ops kcs_bmc_serio_driver_ops = {
0135     .add_device = kcs_bmc_serio_add_device,
0136     .remove_device = kcs_bmc_serio_remove_device,
0137 };
0138
0139 static struct kcs_bmc_driver kcs_bmc_serio_driver = {
0140     .ops = &kcs_bmc_serio_driver_ops,
0141 };
0142
0143 static int kcs_bmc_serio_init(void)
0144 {
0145     kcs_bmc_register_driver(&kcs_bmc_serio_driver);
0146
0147     return 0;
0148 }
0149 module_init(kcs_bmc_serio_init);
0150
0151 static void kcs_bmc_serio_exit(void)
0152 {
0153     kcs_bmc_unregister_driver(&kcs_bmc_serio_driver);
0154 }
0155 module_exit(kcs_bmc_serio_exit);
0156
0157 MODULE_LICENSE("GPL v2");
0158 MODULE_AUTHOR("Andrew Jeffery <andrew@aj.id.au>");
0159 MODULE_DESCRIPTION("Adapter driver for serio access to BMC KCS devices");