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 #ifndef readq
  85 static inline __u64 readq(const volatile void __iomem *addr)
  86 {
  87         const volatile u32 __iomem *p = addr;
  88         u32 low, high;
  89
  90         low = readl(p);
  91         high = readl(p + 1);
  92
  93         return low + ((u64)high << 32);
  94 }
  95 #endif
  96
  97 static void __iomem *rtl_port_map(phys_addr_t addr, unsigned long len)
  98 {
  99         if (rtl_cmd_type == RTL_ADDR_TYPE_MMIO)
 100                 return ioremap(addr, len);
 101         return ioport_map(addr, len);
 102 }
 103
 104 static void rtl_port_unmap(void __iomem *addr)
 105 {
 106         if (addr && rtl_cmd_type == RTL_ADDR_TYPE_MMIO)
 107                 iounmap(addr);
 108         else
 109                 ioport_unmap(addr);
 110 }
 111
 112 static int ibm_rtl_write(u8 value)
 113 {
 114         int ret = 0, count = 0;
 115         static u32 cmd_port_val;
 116
 117         RTL_DEBUG("%s(%d)\n", __FUNCTION__, value);
 118
 119         value = value == 1 ? RTL_CMD_ENTER_PRTM : RTL_CMD_EXIT_PRTM;
 120
 121         mutex_lock(&rtl_lock);
 122
 123         if (ioread8(&rtl_table->rt_status) != value) {
 124                 iowrite8(value, &rtl_table->command);
 125
 126                 switch (rtl_cmd_width) {
 127                 case 8:
 128                         cmd_port_val = ioread8(&rtl_table->cmd_port_value);
 129                         RTL_DEBUG("cmd_port_val = %u\n", cmd_port_val);
 130                         iowrite8((u8)cmd_port_val, rtl_cmd_addr);
 131                         break;
 132                 case 16:
 133                         cmd_port_val = ioread16(&rtl_table->cmd_port_value);
 134                         RTL_DEBUG("cmd_port_val = %u\n", cmd_port_val);
 135                         iowrite16((u16)cmd_port_val, rtl_cmd_addr);
 136                         break;
 137                 case 32:
 138                         cmd_port_val = ioread32(&rtl_table->cmd_port_value);
 139                         RTL_DEBUG("cmd_port_val = %u\n", cmd_port_val);
 140                         iowrite32(cmd_port_val, rtl_cmd_addr);
 141                         break;
 142                 }
 143
 144                 while (ioread8(&rtl_table->command)) {
 145                         msleep(10);
 146                         if (count++ > 500) {
 147                                 pr_err("ibm-rtl: Hardware not responding to "
 148                                         "mode switch request\n");
 149                                 ret = -EIO;
 150                                 break;
 151                         }
 152
 153                 }
 154
 155                 if (ioread8(&rtl_table->command_status)) {
 156                         RTL_DEBUG("command_status reports failed command\n");
 157                         ret = -EIO;
 158                 }
 159         }
 160
 161         mutex_unlock(&rtl_lock);
 162         return ret;
 163 }
 164
 165 static ssize_t rtl_show_version(struct sysdev_class * dev,
 166                                 struct sysdev_class_attribute *attr,
 167                                 char *buf)
 168 {
 169         return sprintf(buf, "%d\n", (int)ioread8(&rtl_table->version));
 170 }
 171
 172 static ssize_t rtl_show_state(struct sysdev_class *dev,
 173                               struct sysdev_class_attribute *attr,
 174                               char *buf)
 175 {
 176         return sprintf(buf, "%d\n", ioread8(&rtl_table->rt_status));
 177 }
 178
 179 static ssize_t rtl_set_state(struct sysdev_class *dev,
 180                              struct sysdev_class_attribute *attr,
 181                              const char *buf,
 182                              size_t count)
 183 {
 184         ssize_t ret;
 185
 186         if (count < 1 || count > 2)
 187                 return -EINVAL;
 188
 189         switch (buf[0]) {
 190         case '0':
 191                 ret = ibm_rtl_write(0);
 192                 break;
 193         case '1':
 194                 ret = ibm_rtl_write(1);
 195                 break;
 196         default:
 197                 ret = -EINVAL;
 198         }
 199         if (ret >= 0)
 200                 ret = count;
 201
 202         return ret;
 203 }
 204
 205 static struct sysdev_class class_rtl = {
 206         .name = "ibm_rtl",
 207 };
 208
 209 static SYSDEV_CLASS_ATTR(version, S_IRUGO, rtl_show_version, NULL);
 210 static SYSDEV_CLASS_ATTR(state, 0600, rtl_show_state, rtl_set_state);
 211
 212 static struct sysdev_class_attribute *rtl_attributes[] = {
 213         &attr_version,
 214         &attr_state,
 215         NULL
 216 };
 217
 218
 219 static int rtl_setup_sysfs(void) {
 220         int ret, i;
 221         ret = sysdev_class_register(&class_rtl);
 222
 223         if (!ret) {
 224                 for (i = 0; rtl_attributes[i]; i ++)
 225                         sysdev_class_create_file(&class_rtl, rtl_attributes[i]);
 226         }
 227         return ret;
 228 }
 229
 230 static void rtl_teardown_sysfs(void) {
 231         int i;
 232         for (i = 0; rtl_attributes[i]; i ++)
 233                 sysdev_class_remove_file(&class_rtl, rtl_attributes[i]);
 234         sysdev_class_unregister(&class_rtl);
 235 }
 236
 237
 238 static struct dmi_system_id __initdata ibm_rtl_dmi_table[] = {
 239         {                                                  \
 240                 .matches = {                               \
 241                         DMI_MATCH(DMI_SYS_VENDOR, "IBM"),  \
 242                 },                                         \
 243         },
 244         { }
 245 };
 246
 247 static int __init ibm_rtl_init(void) {
 248         unsigned long ebda_addr, ebda_size;
 249         unsigned int ebda_kb;
 250         int ret = -ENODEV, i;
 251
 252         if (force)
 253                 pr_warning("ibm-rtl: module loaded by force\n");
 254         /* first ensure that we are running on IBM HW */
 255         else if (efi_enabled || !dmi_check_system(ibm_rtl_dmi_table))
 256                 return -ENODEV;
 257
 258         /* Get the address for the Extended BIOS Data Area */
 259         ebda_addr = get_bios_ebda();
 260         if (!ebda_addr) {
 261                 RTL_DEBUG("no BIOS EBDA found\n");
 262                 return -ENODEV;
 263         }
 264
 265         ebda_map = ioremap(ebda_addr, 4);
 266         if (!ebda_map)
 267                 return -ENOMEM;
 268
 269         /* First word in the EDBA is the Size in KB */
 270         ebda_kb = ioread16(ebda_map);
 271         RTL_DEBUG("EBDA is %d kB\n", ebda_kb);
 272
 273         if (ebda_kb == 0)
 274                 goto out;
 275
 276         iounmap(ebda_map);
 277         ebda_size = ebda_kb*1024;
 278
 279         /* Remap the whole table */
 280         ebda_map = ioremap(ebda_addr, ebda_size);
 281         if (!ebda_map)
 282                 return -ENOMEM;
 283
 284         /* search for the _RTL_ signature at the start of the table */
 285         for (i = 0 ; i < ebda_size/sizeof(unsigned int); i++) {
 286                 struct ibm_rtl_table __iomem * tmp;
 287                 tmp = (struct ibm_rtl_table __iomem *) (ebda_map+i);
 288                 if ((readq(&tmp->signature) & RTL_MASK) == RTL_SIGNATURE) {
 289                         phys_addr_t addr;
 290                         unsigned int plen;
 291                         RTL_DEBUG("found RTL_SIGNATURE at %#llx\n", (u64)tmp);
 292                         rtl_table = tmp;
 293                         /* The address, value, width and offset are platform
 294                          * dependent and found in the ibm_rtl_table */
 295                         rtl_cmd_width = ioread8(&rtl_table->cmd_granularity);
 296                         rtl_cmd_type = ioread8(&rtl_table->cmd_address_type);
 297                         RTL_DEBUG("rtl_cmd_width = %u, rtl_cmd_type = %u\n",
 298                               rtl_cmd_width, rtl_cmd_type);
 299                         addr = ioread32(&rtl_table->cmd_port_address);
 300                         RTL_DEBUG("addr = %#llx\n", (unsigned long long)addr);
 301                         plen = rtl_cmd_width/sizeof(char);
 302                         rtl_cmd_addr = rtl_port_map(addr, plen);
 303                         RTL_DEBUG("rtl_cmd_addr = %#llx\n", (u64)rtl_cmd_addr);
 304                         if (!rtl_cmd_addr) {
 305                                 ret = -ENOMEM;
 306                                 break;
 307                         }
 308                         ret = rtl_setup_sysfs();
 309                         break;
 310                 }
 311         }
 312
 313 out:
 314         if (ret) {
 315                 iounmap(ebda_map);
 316                 rtl_port_unmap(rtl_cmd_addr);
 317         }
 318
 319         return ret;
 320 }
 321
 322 static void __exit ibm_rtl_exit(void)
 323 {
 324         if (rtl_table) {
 325                 RTL_DEBUG("cleaning up");
 326                 /* do not leave the machine in SMI-free mode */
 327                 ibm_rtl_write(0);
 328                 /* unmap, unlink and remove all traces */
 329                 rtl_teardown_sysfs();
 330                 iounmap(ebda_map);
 331                 rtl_port_unmap(rtl_cmd_addr);
 332         }
 333 }
 334
 335 module_init(ibm_rtl_init);
 336 module_exit(ibm_rtl_exit);