arch/powerpc/sysdev/pmi.c

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