drivers/char/ipmi/kcs_bmc_serio.c

   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
  77         /* Use kzalloc() as the allocation is cleaned up with kfree() via serio_unregister_port() */
  78         port = kzalloc(sizeof(*port), GFP_KERNEL);
  79         if (!(priv && port))
  80                 return -ENOMEM;
  81
  82         port->id.type = SERIO_8042;
  83         port->open = kcs_bmc_serio_open;
  84         port->close = kcs_bmc_serio_close;
  85         port->port_data = priv;
  86         port->dev.parent = kcs_bmc->dev;
  87
  88         spin_lock_init(&priv->lock);
  89         priv->port = port;
  90         priv->client.dev = kcs_bmc;
  91         priv->client.ops = &kcs_bmc_serio_client_ops;
  92
  93         spin_lock_irq(&kcs_bmc_serio_instances_lock);
  94         list_add(&priv->entry, &kcs_bmc_serio_instances);
  95         spin_unlock_irq(&kcs_bmc_serio_instances_lock);
  96
  97         serio_register_port(port);
  98
  99         dev_info(kcs_bmc->dev, "Initialised serio client for channel %d", kcs_bmc->channel);
 100
 101         return 0;
 102 }
 103
 104 static int kcs_bmc_serio_remove_device(struct kcs_bmc_device *kcs_bmc)
 105 {
 106         struct kcs_bmc_serio *priv = NULL, *pos;
 107
 108         spin_lock_irq(&kcs_bmc_serio_instances_lock);
 109         list_for_each_entry(pos, &kcs_bmc_serio_instances, entry) {
 110                 if (pos->client.dev == kcs_bmc) {
 111                         priv = pos;
 112                         list_del(&pos->entry);
 113                         break;
 114                 }
 115         }
 116         spin_unlock_irq(&kcs_bmc_serio_instances_lock);
 117
 118         if (!priv)
 119                 return -ENODEV;
 120
 121         /* kfree()s priv->port via put_device() */
 122         serio_unregister_port(priv->port);
 123
 124         /* Ensure the IBF IRQ is disabled if we were the active client */
 125         kcs_bmc_disable_device(kcs_bmc, &priv->client);
 126
 127         devm_kfree(priv->client.dev->dev, priv);
 128
 129         return 0;
 130 }
 131
 132 static const struct kcs_bmc_driver_ops kcs_bmc_serio_driver_ops = {
 133         .add_device = kcs_bmc_serio_add_device,
 134         .remove_device = kcs_bmc_serio_remove_device,
 135 };
 136
 137 static struct kcs_bmc_driver kcs_bmc_serio_driver = {
 138         .ops = &kcs_bmc_serio_driver_ops,
 139 };
 140
 141 static int kcs_bmc_serio_init(void)
 142 {
 143         kcs_bmc_register_driver(&kcs_bmc_serio_driver);
 144
 145         return 0;
 146 }
 147 module_init(kcs_bmc_serio_init);
 148
 149 static void kcs_bmc_serio_exit(void)
 150 {
 151         kcs_bmc_unregister_driver(&kcs_bmc_serio_driver);
 152 }
 153 module_exit(kcs_bmc_serio_exit);
 154
 155 MODULE_LICENSE("GPL v2");
 156 MODULE_AUTHOR("Andrew Jeffery <andrew@aj.id.au>");
 157 MODULE_DESCRIPTION("Adapter driver for serio access to BMC KCS devices");