kernel/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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  26
  27 #include <linux/kernel.h>
  28 #include <linux/delay.h>
  29 #include <linux/module.h>
  30 #include <linux/io.h>
  31 #include <linux/dmi.h>
  32 #include <linux/efi.h>
  33 #include <linux/mutex.h>
  34 #include <asm/bios_ebda.h>
  35
  36 #include <asm-generic/io-64-nonatomic-lo-hi.h>
  37
  38 static bool force;
  39 module_param(force, bool, 0);
  40 MODULE_PARM_DESC(force, "Force driver load, ignore DMI data");
  41
  42 static bool debug;
  43 module_param(debug, bool, 0644);
  44 MODULE_PARM_DESC(debug, "Show debug output");
  45
  46 MODULE_LICENSE("GPL");
  47 MODULE_AUTHOR("Keith Mannthey <kmmanth@us.ibm.com>");
  48 MODULE_AUTHOR("Vernon Mauery <vernux@us.ibm.com>");
  49
  50 #define RTL_ADDR_TYPE_IO    1
  51 #define RTL_ADDR_TYPE_MMIO  2
  52
  53 #define RTL_CMD_ENTER_PRTM  1
  54 #define RTL_CMD_EXIT_PRTM   2
  55
  56 /* The RTL table as presented by the EBDA: */
  57 struct ibm_rtl_table {
  58         char signature[5]; /* signature should be "_RTL_" */
  59         u8 version;
  60         u8 rt_status;
  61         u8 command;
  62         u8 command_status;
  63         u8 cmd_address_type;
  64         u8 cmd_granularity;
  65         u8 cmd_offset;
  66         u16 reserve1;
  67         u32 cmd_port_address; /* platform dependent address */
  68         u32 cmd_port_value;   /* platform dependent value */
  69 } __attribute__((packed));
  70
  71 /* to locate "_RTL_" signature do a masked 5-byte integer compare */
  72 #define RTL_SIGNATURE 0x0000005f4c54525fULL
  73 #define RTL_MASK      0x000000ffffffffffULL
  74
  75 #define RTL_DEBUG(fmt, ...)                             \
  76 do {                                                    \
  77         if (debug)                                      \
  78                 pr_info(fmt, ##__VA_ARGS__);            \
  79 } while (0)
  80
  81 static DEFINE_MUTEX(rtl_lock);
  82 static struct ibm_rtl_table __iomem *rtl_table;
  83 static void __iomem *ebda_map;
  84 static void __iomem *rtl_cmd_addr;
  85 static u8 rtl_cmd_type;
  86 static u8 rtl_cmd_width;
  87
  88 static void __iomem *rtl_port_map(phys_addr_t addr, unsigned long len)
  89 {
  90         if (rtl_cmd_type == RTL_ADDR_TYPE_MMIO)
  91                 return ioremap(addr, len);
  92         return ioport_map(addr, len);
  93 }
  94
  95 static void rtl_port_unmap(void __iomem *addr)
  96 {
  97         if (addr && rtl_cmd_type == RTL_ADDR_TYPE_MMIO)
  98                 iounmap(addr);
  99         else
 100                 ioport_unmap(addr);
 101 }
 102
 103 static int ibm_rtl_write(u8 value)
 104 {
 105         int ret = 0, count = 0;
 106         static u32 cmd_port_val;
 107
 108         RTL_DEBUG("%s(%d)\n", __func__, value);
 109
 110         value = value == 1 ? RTL_CMD_ENTER_PRTM : RTL_CMD_EXIT_PRTM;
 111
 112         mutex_lock(&rtl_lock);
 113
 114         if (ioread8(&rtl_table->rt_status) != value) {
 115                 iowrite8(value, &rtl_table->command);
 116
 117                 switch (rtl_cmd_width) {
 118                 case 8:
 119                         cmd_port_val = ioread8(&rtl_table->cmd_port_value);
 120                         RTL_DEBUG("cmd_port_val = %u\n", cmd_port_val);
 121                         iowrite8((u8)cmd_port_val, rtl_cmd_addr);
 122                         break;
 123                 case 16:
 124                         cmd_port_val = ioread16(&rtl_table->cmd_port_value);
 125                         RTL_DEBUG("cmd_port_val = %u\n", cmd_port_val);
 126                         iowrite16((u16)cmd_port_val, rtl_cmd_addr);
 127                         break;
 128                 case 32:
 129                         cmd_port_val = ioread32(&rtl_table->cmd_port_value);
 130                         RTL_DEBUG("cmd_port_val = %u\n", cmd_port_val);
 131                         iowrite32(cmd_port_val, rtl_cmd_addr);
 132                         break;
 133                 }
 134
 135                 while (ioread8(&rtl_table->command)) {
 136                         msleep(10);
 137                         if (count++ > 500) {
 138                                 pr_err("Hardware not responding to "
 139                                        "mode switch request\n");
 140                                 ret = -EIO;
 141                                 break;
 142                         }
 143
 144                 }
 145
 146                 if (ioread8(&rtl_table->command_status)) {
 147                         RTL_DEBUG("command_status reports failed command\n");
 148                         ret = -EIO;
 149                 }
 150         }
 151
 152         mutex_unlock(&rtl_lock);
 153         return ret;
 154 }
 155
 156 static ssize_t rtl_show_version(struct device *dev,
 157                                 struct device_attribute *attr,
 158                                 char *buf)
 159 {
 160         return sprintf(buf, "%d\n", (int)ioread8(&rtl_table->version));
 161 }
 162
 163 static ssize_t rtl_show_state(struct device *dev,
 164                               struct device_attribute *attr,
 165                               char *buf)
 166 {
 167         return sprintf(buf, "%d\n", ioread8(&rtl_table->rt_status));
 168 }
 169
 170 static ssize_t rtl_set_state(struct device *dev,
 171                              struct device_attribute *attr,
 172                              const char *buf,
 173                              size_t count)
 174 {
 175         ssize_t ret;
 176
 177         if (count < 1 || count > 2)
 178                 return -EINVAL;
 179
 180         switch (buf[0]) {
 181         case '0':
 182                 ret = ibm_rtl_write(0);
 183                 break;
 184         case '1':
 185                 ret = ibm_rtl_write(1);
 186                 break;
 187         default:
 188                 ret = -EINVAL;
 189         }
 190         if (ret >= 0)
 191                 ret = count;
 192
 193         return ret;
 194 }
 195
 196 static struct bus_type rtl_subsys = {
 197         .name = "ibm_rtl",
 198         .dev_name = "ibm_rtl",
 199 };
 200
 201 static DEVICE_ATTR(version, S_IRUGO, rtl_show_version, NULL);
 202 static DEVICE_ATTR(state, 0600, rtl_show_state, rtl_set_state);
 203
 204 static struct device_attribute *rtl_attributes[] = {
 205         &dev_attr_version,
 206         &dev_attr_state,
 207         NULL
 208 };
 209
 210
 211 static int rtl_setup_sysfs(void) {
 212         int ret, i;
 213
 214         ret = subsys_system_register(&rtl_subsys, NULL);
 215         if (!ret) {
 216                 for (i = 0; rtl_attributes[i]; i ++)
 217                         device_create_file(rtl_subsys.dev_root, rtl_attributes[i]);
 218         }
 219         return ret;
 220 }
 221
 222 static void rtl_teardown_sysfs(void) {
 223         int i;
 224         for (i = 0; rtl_attributes[i]; i ++)
 225                 device_remove_file(rtl_subsys.dev_root, rtl_attributes[i]);
 226         bus_unregister(&rtl_subsys);
 227 }
 228
 229
 230 static struct dmi_system_id __initdata ibm_rtl_dmi_table[] = {
 231         {                                                  \
 232                 .matches = {                               \
 233                         DMI_MATCH(DMI_SYS_VENDOR, "IBM"),  \
 234                 },                                         \
 235         },
 236         { }
 237 };
 238
 239 static int __init ibm_rtl_init(void) {
 240         unsigned long ebda_addr, ebda_size;
 241         unsigned int ebda_kb;
 242         int ret = -ENODEV, i;
 243
 244         if (force)
 245                 pr_warn("module loaded by force\n");
 246         /* first ensure that we are running on IBM HW */
 247         else if (efi_enabled(EFI_BOOT) || !dmi_check_system(ibm_rtl_dmi_table))
 248                 return -ENODEV;
 249
 250         /* Get the address for the Extended BIOS Data Area */
 251         ebda_addr = get_bios_ebda();
 252         if (!ebda_addr) {
 253                 RTL_DEBUG("no BIOS EBDA found\n");
 254                 return -ENODEV;
 255         }
 256
 257         ebda_map = ioremap(ebda_addr, 4);
 258         if (!ebda_map)
 259                 return -ENOMEM;
 260
 261         /* First word in the EDBA is the Size in KB */
 262         ebda_kb = ioread16(ebda_map);
 263         RTL_DEBUG("EBDA is %d kB\n", ebda_kb);
 264
 265         if (ebda_kb == 0)
 266                 goto out;
 267
 268         iounmap(ebda_map);
 269         ebda_size = ebda_kb*1024;
 270
 271         /* Remap the whole table */
 272         ebda_map = ioremap(ebda_addr, ebda_size);
 273         if (!ebda_map)
 274                 return -ENOMEM;
 275
 276         /* search for the _RTL_ signature at the start of the table */
 277         for (i = 0 ; i < ebda_size/sizeof(unsigned int); i++) {
 278                 struct ibm_rtl_table __iomem * tmp;
 279                 tmp = (struct ibm_rtl_table __iomem *) (ebda_map+i);
 280                 if ((readq(&tmp->signature) & RTL_MASK) == RTL_SIGNATURE) {
 281                         phys_addr_t addr;
 282                         unsigned int plen;
 283                         RTL_DEBUG("found RTL_SIGNATURE at %p\n", tmp);
 284                         rtl_table = tmp;
 285                         /* The address, value, width and offset are platform
 286                          * dependent and found in the ibm_rtl_table */
 287                         rtl_cmd_width = ioread8(&rtl_table->cmd_granularity);
 288                         rtl_cmd_type = ioread8(&rtl_table->cmd_address_type);
 289                         RTL_DEBUG("rtl_cmd_width = %u, rtl_cmd_type = %u\n",
 290                                   rtl_cmd_width, rtl_cmd_type);
 291                         addr = ioread32(&rtl_table->cmd_port_address);
 292                         RTL_DEBUG("addr = %#llx\n", (unsigned long long)addr);
 293                         plen = rtl_cmd_width/sizeof(char);
 294                         rtl_cmd_addr = rtl_port_map(addr, plen);
 295                         RTL_DEBUG("rtl_cmd_addr = %p\n", rtl_cmd_addr);
 296                         if (!rtl_cmd_addr) {
 297                                 ret = -ENOMEM;
 298                                 break;
 299                         }
 300                         ret = rtl_setup_sysfs();
 301                         break;
 302                 }
 303         }
 304
 305 out:
 306         if (ret) {
 307                 iounmap(ebda_map);
 308                 rtl_port_unmap(rtl_cmd_addr);
 309         }
 310
 311         return ret;
 312 }
 313
 314 static void __exit ibm_rtl_exit(void)
 315 {
 316         if (rtl_table) {
 317                 RTL_DEBUG("cleaning up");
 318                 /* do not leave the machine in SMI-free mode */
 319                 ibm_rtl_write(0);
 320                 /* unmap, unlink and remove all traces */
 321                 rtl_teardown_sysfs();
 322                 iounmap(ebda_map);
 323                 rtl_port_unmap(rtl_cmd_addr);
 324         }
 325 }
 326
 327 module_init(ibm_rtl_init);
 328 module_exit(ibm_rtl_exit);