drivers/platform/x86/ibm_rtl.c

   1 /*
   2  * IBM Real-Time Linux driver
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  17  *
  18  * Copyright (C) IBM Corporation, 2010
  19  *
  20  * Author: Keith Mannthey <kmannth@us.ibm.com>
  21  *         Vernon Mauery <vernux@us.ibm.com>
  22  *
  23  */
  24
  25 #include <linux/kernel.h>
  26 #include <linux/delay.h>
  27 #include <linux/module.h>
  28 #include <linux/io.h>
  29 #include <linux/sysdev.h>
  30 #include <linux/dmi.h>
  31 #include <linux/efi.h>
  32 #include <linux/mutex.h>
  33 #include <asm/bios_ebda.h>
  34
  35 static bool force;
  36 module_param(force, bool, 0);
  37 MODULE_PARM_DESC(force, "Force driver load, ignore DMI data");
  38
  39 static bool debug;
  40 module_param(debug, bool, 0644);
  41 MODULE_PARM_DESC(debug, "Show debug output");
  42
  43 MODULE_LICENSE("GPL");
  44 MODULE_AUTHOR("Keith Mannthey <kmmanth@us.ibm.com>");
  45 MODULE_AUTHOR("Vernon Mauery <vernux@us.ibm.com>");
  46
  47 #define RTL_ADDR_TYPE_IO    1
  48 #define RTL_ADDR_TYPE_MMIO  2
  49
  50 #define RTL_CMD_ENTER_PRTM  1
  51 #define RTL_CMD_EXIT_PRTM   2
  52
  53 /* The RTL table as presented by the EBDA: */
  54 struct ibm_rtl_table {
  55         char signature[5]; /* signature should be "_RTL_" */
  56         u8 version;
  57         u8 rt_status;
  58         u8 command;
  59         u8 command_status;
  60         u8 cmd_address_type;
  61         u8 cmd_granularity;
  62         u8 cmd_offset;
  63         u16 reserve1;
  64         u32 cmd_port_address; /* platform dependent address */
  65         u32 cmd_port_value;   /* platform dependent value */
  66 } __attribute__((packed));
  67
  68 /* to locate "_RTL_" signature do a masked 5-byte integer compare */
  69 #define RTL_SIGNATURE 0x0000005f4c54525fULL
  70 #define RTL_MASK      0x000000ffffffffffULL
  71
  72 #define RTL_DEBUG(A, ...) do { \
  73         if (debug) \
  74                 pr_info("ibm-rtl: " A, ##__VA_ARGS__ ); \
  75 } while (0)
  76
  77 static DEFINE_MUTEX(rtl_lock);
  78 static struct ibm_rtl_table __iomem *rtl_table;
  79 static void __iomem *ebda_map;
  80 static void __iomem *rtl_cmd_addr;
  81 static u8 rtl_cmd_type;
  82 static u8 rtl_cmd_width;
  83
  84 static void __iomem *rtl_port_map(phys_addr_t addr, unsigned long len)
  85 {
  86         if (rtl_cmd_type == RTL_ADDR_TYPE_MMIO)
  87                 return ioremap(addr, len);
  88         return ioport_map(addr, len);
  89 }
  90
  91 static void rtl_port_unmap(void __iomem *addr)
  92 {
  93         if (addr && rtl_cmd_type == RTL_ADDR_TYPE_MMIO)
  94                 iounmap(addr);
  95         else
  96                 ioport_unmap(addr);
  97 }
  98
  99 static int ibm_rtl_write(u8 value)
 100 {
 101         int ret = 0, count = 0;
 102         static u32 cmd_port_val;
 103
 104         RTL_DEBUG("%s(%d)\n", __FUNCTION__, value);
 105
 106         value = value == 1 ? RTL_CMD_ENTER_PRTM : RTL_CMD_EXIT_PRTM;
 107
 108         mutex_lock(&rtl_lock);
 109
 110         if (ioread8(&rtl_table->rt_status) != value) {
 111                 iowrite8(value, &rtl_table->command);
 112
 113                 switch (rtl_cmd_width) {
 114                 case 8:
 115                         cmd_port_val = ioread8(&rtl_table->cmd_port_value);
 116                         RTL_DEBUG("cmd_port_val = %u\n", cmd_port_val);
 117                         iowrite8((u8)cmd_port_val, rtl_cmd_addr);
 118                         break;
 119                 case 16:
 120                         cmd_port_val = ioread16(&rtl_table->cmd_port_value);
 121                         RTL_DEBUG("cmd_port_val = %u\n", cmd_port_val);
 122                         iowrite16((u16)cmd_port_val, rtl_cmd_addr);
 123                         break;
 124                 case 32:
 125                         cmd_port_val = ioread32(&rtl_table->cmd_port_value);
 126                         RTL_DEBUG("cmd_port_val = %u\n", cmd_port_val);
 127                         iowrite32(cmd_port_val, rtl_cmd_addr);
 128                         break;
 129                 }
 130
 131                 while (ioread8(&rtl_table->command)) {
 132                         msleep(10);
 133                         if (count++ > 500) {
 134                                 pr_err("ibm-rtl: Hardware not responding to "
 135                                         "mode switch request\n");
 136                                 ret = -EIO;
 137                                 break;
 138                         }
 139
 140                 }
 141
 142                 if (ioread8(&rtl_table->command_status)) {
 143                         RTL_DEBUG("command_status reports failed command\n");
 144                         ret = -EIO;
 145                 }
 146         }
 147
 148         mutex_unlock(&rtl_lock);
 149         return ret;
 150 }
 151
 152 static ssize_t rtl_show_version(struct sysdev_class * dev,
 153                                 struct sysdev_class_attribute *attr,
 154                                 char *buf)
 155 {
 156         return sprintf(buf, "%d\n", (int)ioread8(&rtl_table->version));
 157 }
 158
 159 static ssize_t rtl_show_state(struct sysdev_class *dev,
 160                               struct sysdev_class_attribute *attr,
 161                               char *buf)
 162 {
 163         return sprintf(buf, "%d\n", ioread8(&rtl_table->rt_status));
 164 }
 165
 166 static ssize_t rtl_set_state(struct sysdev_class *dev,
 167                              struct sysdev_class_attribute *attr,
 168                              const char *buf,
 169                              size_t count)
 170 {
 171         ssize_t ret;
 172
 173         if (count < 1 || count > 2)
 174                 return -EINVAL;
 175
 176         switch (buf[0]) {
 177         case '0':
 178                 ret = ibm_rtl_write(0);
 179                 break;
 180         case '1':
 181                 ret = ibm_rtl_write(1);
 182                 break;
 183         default:
 184                 ret = -EINVAL;
 185         }
 186         if (ret >= 0)
 187                 ret = count;
 188
 189         return ret;
 190 }
 191
 192 static struct sysdev_class class_rtl = {
 193         .name = "ibm_rtl",
 194 };
 195
 196 static SYSDEV_CLASS_ATTR(version, S_IRUGO, rtl_show_version, NULL);
 197 static SYSDEV_CLASS_ATTR(state, 0600, rtl_show_state, rtl_set_state);
 198
 199 static struct sysdev_class_attribute *rtl_attributes[] = {
 200         &attr_version,
 201         &attr_state,
 202         NULL
 203 };
 204
 205
 206 static int rtl_setup_sysfs(void) {
 207         int ret, i;
 208         ret = sysdev_class_register(&class_rtl);
 209
 210         if (!ret) {
 211                 for (i = 0; rtl_attributes[i]; i ++)
 212                         sysdev_class_create_file(&class_rtl, rtl_attributes[i]);
 213         }
 214         return ret;
 215 }
 216
 217 static void rtl_teardown_sysfs(void) {
 218         int i;
 219         for (i = 0; rtl_attributes[i]; i ++)
 220                 sysdev_class_remove_file(&class_rtl, rtl_attributes[i]);
 221         sysdev_class_unregister(&class_rtl);
 222 }
 223
 224
 225 static struct dmi_system_id __initdata ibm_rtl_dmi_table[] = {
 226         {                                                  \
 227                 .matches = {                               \
 228                         DMI_MATCH(DMI_SYS_VENDOR, "IBM"),  \
 229                 },                                         \
 230         },
 231         { }
 232 };
 233
 234 static int __init ibm_rtl_init(void) {
 235         unsigned long ebda_addr, ebda_size;
 236         unsigned int ebda_kb;
 237         int ret = -ENODEV, i;
 238
 239         if (force)
 240                 pr_warning("ibm-rtl: module loaded by force\n");
 241         /* first ensure that we are running on IBM HW */
 242         else if (efi_enabled || !dmi_check_system(ibm_rtl_dmi_table))
 243                 return -ENODEV;
 244
 245         /* Get the address for the Extended BIOS Data Area */
 246         ebda_addr = get_bios_ebda();
 247         if (!ebda_addr) {
 248                 RTL_DEBUG("no BIOS EBDA found\n");
 249                 return -ENODEV;
 250         }
 251
 252         ebda_map = ioremap(ebda_addr, 4);
 253         if (!ebda_map)
 254                 return -ENOMEM;
 255
 256         /* First word in the EDBA is the Size in KB */
 257         ebda_kb = ioread16(ebda_map);
 258         RTL_DEBUG("EBDA is %d kB\n", ebda_kb);
 259
 260         if (ebda_kb == 0)
 261                 goto out;
 262
 263         iounmap(ebda_map);
 264         ebda_size = ebda_kb*1024;
 265
 266         /* Remap the whole table */
 267         ebda_map = ioremap(ebda_addr, ebda_size);
 268         if (!ebda_map)
 269                 return -ENOMEM;
 270
 271         /* search for the _RTL_ signature at the start of the table */
 272         for (i = 0 ; i < ebda_size/sizeof(unsigned int); i++) {
 273                 struct ibm_rtl_table __iomem * tmp;
 274                 tmp = (struct ibm_rtl_table __iomem *) (ebda_map+i);
 275                 if ((readq(&tmp->signature) & RTL_MASK) == RTL_SIGNATURE) {
 276                         phys_addr_t addr;
 277                         unsigned int plen;
 278                         RTL_DEBUG("found RTL_SIGNATURE at %#llx\n", (u64)tmp);
 279                         rtl_table = tmp;
 280                         /* The address, value, width and offset are platform
 281                          * dependent and found in the ibm_rtl_table */
 282                         rtl_cmd_width = ioread8(&rtl_table->cmd_granularity);
 283                         rtl_cmd_type = ioread8(&rtl_table->cmd_address_type);
 284                         RTL_DEBUG("rtl_cmd_width = %u, rtl_cmd_type = %u\n",
 285                               rtl_cmd_width, rtl_cmd_type);
 286                         addr = ioread32(&rtl_table->cmd_port_address);
 287                         RTL_DEBUG("addr = %#llx\n", (unsigned long long)addr);
 288                         plen = rtl_cmd_width/sizeof(char);
 289                         rtl_cmd_addr = rtl_port_map(addr, plen);
 290                         RTL_DEBUG("rtl_cmd_addr = %#llx\n", (u64)rtl_cmd_addr);
 291                         if (!rtl_cmd_addr) {
 292                                 ret = -ENOMEM;
 293                                 break;
 294                         }
 295                         ret = rtl_setup_sysfs();
 296                         break;
 297                 }
 298         }
 299
 300 out:
 301         if (ret) {
 302                 iounmap(ebda_map);
 303                 rtl_port_unmap(rtl_cmd_addr);
 304         }
 305
 306         return ret;
 307 }
 308
 309 static void __exit ibm_rtl_exit(void)
 310 {
 311         if (rtl_table) {
 312                 RTL_DEBUG("cleaning up");
 313                 /* do not leave the machine in SMI-free mode */
 314                 ibm_rtl_write(0);
 315                 /* unmap, unlink and remove all traces */
 316                 rtl_teardown_sysfs();
 317                 iounmap(ebda_map);
 318                 rtl_port_unmap(rtl_cmd_addr);
 319         }
 320 }
 321
 322 module_init(ibm_rtl_init);
 323 module_exit(ibm_rtl_exit);