linux/arch/powerpc/sysdev/pmi.c
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   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * pmi driver
   4 *
   5 * (C) Copyright IBM Deutschland Entwicklung GmbH 2005
   6 *
   7 * PMI (Platform Management Interrupt) is a way to communicate
   8 * with the BMC (Baseboard Management Controller) via interrupts.
   9 * Unlike IPMI it is bidirectional and has a low latency.
  10 *
  11 * Author: Christian Krafft <krafft@de.ibm.com>
  12 */
  13
  14#include <linux/interrupt.h>
  15#include <linux/slab.h>
  16#include <linux/completion.h>
  17#include <linux/spinlock.h>
  18#include <linux/module.h>
  19#include <linux/workqueue.h>
  20#include <linux/of_device.h>
  21#include <linux/of_platform.h>
  22
  23#include <asm/io.h>
  24#include <asm/pmi.h>
  25#include <asm/prom.h>
  26
  27struct pmi_data {
  28        struct list_head        handler;
  29        spinlock_t              handler_spinlock;
  30        spinlock_t              pmi_spinlock;
  31        struct mutex            msg_mutex;
  32        pmi_message_t           msg;
  33        struct completion       *completion;
  34        struct platform_device  *dev;
  35        int                     irq;
  36        u8 __iomem              *pmi_reg;
  37        struct work_struct      work;
  38};
  39
  40static struct pmi_data *data;
  41
  42static irqreturn_t pmi_irq_handler(int irq, void *dev_id)
  43{
  44        u8 type;
  45        int rc;
  46
  47        spin_lock(&data->pmi_spinlock);
  48
  49        type = ioread8(data->pmi_reg + PMI_READ_TYPE);
  50        pr_debug("pmi: got message of type %d\n", type);
  51
  52        if (type & PMI_ACK && !data->completion) {
  53                printk(KERN_WARNING "pmi: got unexpected ACK message.\n");
  54                rc = -EIO;
  55                goto unlock;
  56        }
  57
  58        if (data->completion && !(type & PMI_ACK)) {
  59                printk(KERN_WARNING "pmi: expected ACK, but got %d\n", type);
  60                rc = -EIO;
  61                goto unlock;
  62        }
  63
  64        data->msg.type = type;
  65        data->msg.data0 = ioread8(data->pmi_reg + PMI_READ_DATA0);
  66        data->msg.data1 = ioread8(data->pmi_reg + PMI_READ_DATA1);
  67        data->msg.data2 = ioread8(data->pmi_reg + PMI_READ_DATA2);
  68        rc = 0;
  69unlock:
  70        spin_unlock(&data->pmi_spinlock);
  71
  72        if (rc == -EIO) {
  73                rc = IRQ_HANDLED;
  74                goto out;
  75        }
  76
  77        if (data->msg.type & PMI_ACK) {
  78                complete(data->completion);
  79                rc = IRQ_HANDLED;
  80                goto out;
  81        }
  82
  83        schedule_work(&data->work);
  84
  85        rc = IRQ_HANDLED;
  86out:
  87        return rc;
  88}
  89
  90
  91static const struct of_device_id pmi_match[] = {
  92        { .type = "ibm,pmi", .name = "ibm,pmi" },
  93        { .type = "ibm,pmi" },
  94        {},
  95};
  96
  97MODULE_DEVICE_TABLE(of, pmi_match);
  98
  99static void pmi_notify_handlers(struct work_struct *work)
 100{
 101        struct pmi_handler *handler;
 102
 103        spin_lock(&data->handler_spinlock);
 104        list_for_each_entry(handler, &data->handler, node) {
 105                pr_debug("pmi: notifying handler %p\n", handler);
 106                if (handler->type == data->msg.type)
 107                        handler->handle_pmi_message(data->msg);
 108        }
 109        spin_unlock(&data->handler_spinlock);
 110}
 111
 112static int pmi_of_probe(struct platform_device *dev)
 113{
 114        struct device_node *np = dev->dev.of_node;
 115        int rc;
 116
 117        if (data) {
 118                printk(KERN_ERR "pmi: driver has already been initialized.\n");
 119                rc = -EBUSY;
 120                goto out;
 121        }
 122
 123        data = kzalloc(sizeof(struct pmi_data), GFP_KERNEL);
 124        if (!data) {
 125                printk(KERN_ERR "pmi: could not allocate memory.\n");
 126                rc = -ENOMEM;
 127                goto out;
 128        }
 129
 130        data->pmi_reg = of_iomap(np, 0);
 131        if (!data->pmi_reg) {
 132                printk(KERN_ERR "pmi: invalid register address.\n");
 133                rc = -EFAULT;
 134                goto error_cleanup_data;
 135        }
 136
 137        INIT_LIST_HEAD(&data->handler);
 138
 139        mutex_init(&data->msg_mutex);
 140        spin_lock_init(&data->pmi_spinlock);
 141        spin_lock_init(&data->handler_spinlock);
 142
 143        INIT_WORK(&data->work, pmi_notify_handlers);
 144
 145        data->dev = dev;
 146
 147        data->irq = irq_of_parse_and_map(np, 0);
 148        if (!data->irq) {
 149                printk(KERN_ERR "pmi: invalid interrupt.\n");
 150                rc = -EFAULT;
 151                goto error_cleanup_iomap;
 152        }
 153
 154        rc = request_irq(data->irq, pmi_irq_handler, 0, "pmi", NULL);
 155        if (rc) {
 156                printk(KERN_ERR "pmi: can't request IRQ %d: returned %d\n",
 157                                data->irq, rc);
 158                goto error_cleanup_iomap;
 159        }
 160
 161        printk(KERN_INFO "pmi: found pmi device at addr %p.\n", data->pmi_reg);
 162
 163        goto out;
 164
 165error_cleanup_iomap:
 166        iounmap(data->pmi_reg);
 167
 168error_cleanup_data:
 169        kfree(data);
 170
 171out:
 172        return rc;
 173}
 174
 175static int pmi_of_remove(struct platform_device *dev)
 176{
 177        struct pmi_handler *handler, *tmp;
 178
 179        free_irq(data->irq, NULL);
 180        iounmap(data->pmi_reg);
 181
 182        spin_lock(&data->handler_spinlock);
 183
 184        list_for_each_entry_safe(handler, tmp, &data->handler, node)
 185                list_del(&handler->node);
 186
 187        spin_unlock(&data->handler_spinlock);
 188
 189        kfree(data);
 190        data = NULL;
 191
 192        return 0;
 193}
 194
 195static struct platform_driver pmi_of_platform_driver = {
 196        .probe          = pmi_of_probe,
 197        .remove         = pmi_of_remove,
 198        .driver = {
 199                .name = "pmi",
 200                .of_match_table = pmi_match,
 201        },
 202};
 203module_platform_driver(pmi_of_platform_driver);
 204
 205int pmi_send_message(pmi_message_t msg)
 206{
 207        unsigned long flags;
 208        DECLARE_COMPLETION_ONSTACK(completion);
 209
 210        if (!data)
 211                return -ENODEV;
 212
 213        mutex_lock(&data->msg_mutex);
 214
 215        data->msg = msg;
 216        pr_debug("pmi_send_message: msg is %08x\n", *(u32*)&msg);
 217
 218        data->completion = &completion;
 219
 220        spin_lock_irqsave(&data->pmi_spinlock, flags);
 221        iowrite8(msg.data0, data->pmi_reg + PMI_WRITE_DATA0);
 222        iowrite8(msg.data1, data->pmi_reg + PMI_WRITE_DATA1);
 223        iowrite8(msg.data2, data->pmi_reg + PMI_WRITE_DATA2);
 224        iowrite8(msg.type, data->pmi_reg + PMI_WRITE_TYPE);
 225        spin_unlock_irqrestore(&data->pmi_spinlock, flags);
 226
 227        pr_debug("pmi_send_message: wait for completion\n");
 228
 229        wait_for_completion_interruptible_timeout(data->completion,
 230                                                  PMI_TIMEOUT);
 231
 232        data->completion = NULL;
 233
 234        mutex_unlock(&data->msg_mutex);
 235
 236        return 0;
 237}
 238EXPORT_SYMBOL_GPL(pmi_send_message);
 239
 240int pmi_register_handler(struct pmi_handler *handler)
 241{
 242        if (!data)
 243                return -ENODEV;
 244
 245        spin_lock(&data->handler_spinlock);
 246        list_add_tail(&handler->node, &data->handler);
 247        spin_unlock(&data->handler_spinlock);
 248
 249        return 0;
 250}
 251EXPORT_SYMBOL_GPL(pmi_register_handler);
 252
 253void pmi_unregister_handler(struct pmi_handler *handler)
 254{
 255        if (!data)
 256                return;
 257
 258        pr_debug("pmi: unregistering handler %p\n", handler);
 259
 260        spin_lock(&data->handler_spinlock);
 261        list_del(&handler->node);
 262        spin_unlock(&data->handler_spinlock);
 263}
 264EXPORT_SYMBOL_GPL(pmi_unregister_handler);
 265
 266MODULE_LICENSE("GPL");
 267MODULE_AUTHOR("Christian Krafft <krafft@de.ibm.com>");
 268MODULE_DESCRIPTION("IBM Platform Management Interrupt driver");
 269
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