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