arch/powerpc/platforms/powernv/opal-lpc.c

   1 /*
   2  * PowerNV LPC bus handling.
   3  *
   4  * Copyright 2013 IBM Corp.
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <linux/kernel.h>
  13 #include <linux/of.h>
  14 #include <linux/bug.h>
  15 #include <linux/io.h>
  16 #include <linux/slab.h>
  17
  18 #include <asm/machdep.h>
  19 #include <asm/firmware.h>
  20 #include <asm/opal.h>
  21 #include <asm/prom.h>
  22 #include <linux/uaccess.h>
  23 #include <asm/debugfs.h>
  24 #include <asm/isa-bridge.h>
  25
  26 static int opal_lpc_chip_id = -1;
  27
  28 static u8 opal_lpc_inb(unsigned long port)
  29 {
  30         int64_t rc;
  31         __be32 data;
  32
  33         if (opal_lpc_chip_id < 0 || port > 0xffff)
  34                 return 0xff;
  35         rc = opal_lpc_read(opal_lpc_chip_id, OPAL_LPC_IO, port, &data, 1);
  36         return rc ? 0xff : be32_to_cpu(data);
  37 }
  38
  39 static __le16 __opal_lpc_inw(unsigned long port)
  40 {
  41         int64_t rc;
  42         __be32 data;
  43
  44         if (opal_lpc_chip_id < 0 || port > 0xfffe)
  45                 return 0xffff;
  46         if (port & 1)
  47                 return (__le16)opal_lpc_inb(port) << 8 | opal_lpc_inb(port + 1);
  48         rc = opal_lpc_read(opal_lpc_chip_id, OPAL_LPC_IO, port, &data, 2);
  49         return rc ? 0xffff : be32_to_cpu(data);
  50 }
  51 static u16 opal_lpc_inw(unsigned long port)
  52 {
  53         return le16_to_cpu(__opal_lpc_inw(port));
  54 }
  55
  56 static __le32 __opal_lpc_inl(unsigned long port)
  57 {
  58         int64_t rc;
  59         __be32 data;
  60
  61         if (opal_lpc_chip_id < 0 || port > 0xfffc)
  62                 return 0xffffffff;
  63         if (port & 3)
  64                 return (__le32)opal_lpc_inb(port    ) << 24 |
  65                        (__le32)opal_lpc_inb(port + 1) << 16 |
  66                        (__le32)opal_lpc_inb(port + 2) <<  8 |
  67                                opal_lpc_inb(port + 3);
  68         rc = opal_lpc_read(opal_lpc_chip_id, OPAL_LPC_IO, port, &data, 4);
  69         return rc ? 0xffffffff : be32_to_cpu(data);
  70 }
  71
  72 static u32 opal_lpc_inl(unsigned long port)
  73 {
  74         return le32_to_cpu(__opal_lpc_inl(port));
  75 }
  76
  77 static void opal_lpc_outb(u8 val, unsigned long port)
  78 {
  79         if (opal_lpc_chip_id < 0 || port > 0xffff)
  80                 return;
  81         opal_lpc_write(opal_lpc_chip_id, OPAL_LPC_IO, port, val, 1);
  82 }
  83
  84 static void __opal_lpc_outw(__le16 val, unsigned long port)
  85 {
  86         if (opal_lpc_chip_id < 0 || port > 0xfffe)
  87                 return;
  88         if (port & 1) {
  89                 opal_lpc_outb(val >> 8, port);
  90                 opal_lpc_outb(val     , port + 1);
  91                 return;
  92         }
  93         opal_lpc_write(opal_lpc_chip_id, OPAL_LPC_IO, port, val, 2);
  94 }
  95
  96 static void opal_lpc_outw(u16 val, unsigned long port)
  97 {
  98         __opal_lpc_outw(cpu_to_le16(val), port);
  99 }
 100
 101 static void __opal_lpc_outl(__le32 val, unsigned long port)
 102 {
 103         if (opal_lpc_chip_id < 0 || port > 0xfffc)
 104                 return;
 105         if (port & 3) {
 106                 opal_lpc_outb(val >> 24, port);
 107                 opal_lpc_outb(val >> 16, port + 1);
 108                 opal_lpc_outb(val >>  8, port + 2);
 109                 opal_lpc_outb(val      , port + 3);
 110                 return;
 111         }
 112         opal_lpc_write(opal_lpc_chip_id, OPAL_LPC_IO, port, val, 4);
 113 }
 114
 115 static void opal_lpc_outl(u32 val, unsigned long port)
 116 {
 117         __opal_lpc_outl(cpu_to_le32(val), port);
 118 }
 119
 120 static void opal_lpc_insb(unsigned long p, void *b, unsigned long c)
 121 {
 122         u8 *ptr = b;
 123
 124         while(c--)
 125                 *(ptr++) = opal_lpc_inb(p);
 126 }
 127
 128 static void opal_lpc_insw(unsigned long p, void *b, unsigned long c)
 129 {
 130         __le16 *ptr = b;
 131
 132         while(c--)
 133                 *(ptr++) = __opal_lpc_inw(p);
 134 }
 135
 136 static void opal_lpc_insl(unsigned long p, void *b, unsigned long c)
 137 {
 138         __le32 *ptr = b;
 139
 140         while(c--)
 141                 *(ptr++) = __opal_lpc_inl(p);
 142 }
 143
 144 static void opal_lpc_outsb(unsigned long p, const void *b, unsigned long c)
 145 {
 146         const u8 *ptr = b;
 147
 148         while(c--)
 149                 opal_lpc_outb(*(ptr++), p);
 150 }
 151
 152 static void opal_lpc_outsw(unsigned long p, const void *b, unsigned long c)
 153 {
 154         const __le16 *ptr = b;
 155
 156         while(c--)
 157                 __opal_lpc_outw(*(ptr++), p);
 158 }
 159
 160 static void opal_lpc_outsl(unsigned long p, const void *b, unsigned long c)
 161 {
 162         const __le32 *ptr = b;
 163
 164         while(c--)
 165                 __opal_lpc_outl(*(ptr++), p);
 166 }
 167
 168 static const struct ppc_pci_io opal_lpc_io = {
 169         .inb    = opal_lpc_inb,
 170         .inw    = opal_lpc_inw,
 171         .inl    = opal_lpc_inl,
 172         .outb   = opal_lpc_outb,
 173         .outw   = opal_lpc_outw,
 174         .outl   = opal_lpc_outl,
 175         .insb   = opal_lpc_insb,
 176         .insw   = opal_lpc_insw,
 177         .insl   = opal_lpc_insl,
 178         .outsb  = opal_lpc_outsb,
 179         .outsw  = opal_lpc_outsw,
 180         .outsl  = opal_lpc_outsl,
 181 };
 182
 183 #ifdef CONFIG_DEBUG_FS
 184 struct lpc_debugfs_entry {
 185         enum OpalLPCAddressType lpc_type;
 186 };
 187
 188 static ssize_t lpc_debug_read(struct file *filp, char __user *ubuf,
 189                               size_t count, loff_t *ppos)
 190 {
 191         struct lpc_debugfs_entry *lpc = filp->private_data;
 192         u32 data, pos, len, todo;
 193         int rc;
 194
 195         if (!access_ok(VERIFY_WRITE, ubuf, count))
 196                 return -EFAULT;
 197
 198         todo = count;
 199         while (todo) {
 200                 pos = *ppos;
 201
 202                 /*
 203                  * Select access size based on count and alignment and
 204                  * access type. IO and MEM only support byte acceses,
 205                  * FW supports all 3.
 206                  */
 207                 len = 1;
 208                 if (lpc->lpc_type == OPAL_LPC_FW) {
 209                         if (todo > 3 && (pos & 3) == 0)
 210                                 len = 4;
 211                         else if (todo > 1 && (pos & 1) == 0)
 212                                 len = 2;
 213                 }
 214                 rc = opal_lpc_read(opal_lpc_chip_id, lpc->lpc_type, pos,
 215                                    &data, len);
 216                 if (rc)
 217                         return -ENXIO;
 218
 219                 /*
 220                  * Now there is some trickery with the data returned by OPAL
 221                  * as it's the desired data right justified in a 32-bit BE
 222                  * word.
 223                  *
 224                  * This is a very bad interface and I'm to blame for it :-(
 225                  *
 226                  * So we can't just apply a 32-bit swap to what comes from OPAL,
 227                  * because user space expects the *bytes* to be in their proper
 228                  * respective positions (ie, LPC position).
 229                  *
 230                  * So what we really want to do here is to shift data right
 231                  * appropriately on a LE kernel.
 232                  *
 233                  * IE. If the LPC transaction has bytes B0, B1, B2 and B3 in that
 234                  * order, we have in memory written to by OPAL at the "data"
 235                  * pointer:
 236                  *
 237                  *               Bytes:      OPAL "data"   LE "data"
 238                  *   32-bit:   B0 B1 B2 B3   B0B1B2B3      B3B2B1B0
 239                  *   16-bit:   B0 B1         0000B0B1      B1B00000
 240                  *    8-bit:   B0            000000B0      B0000000
 241                  *
 242                  * So a BE kernel will have the leftmost of the above in the MSB
 243                  * and rightmost in the LSB and can just then "cast" the u32 "data"
 244                  * down to the appropriate quantity and write it.
 245                  *
 246                  * However, an LE kernel can't. It doesn't need to swap because a
 247                  * load from data followed by a store to user are going to preserve
 248                  * the byte ordering which is the wire byte order which is what the
 249                  * user wants, but in order to "crop" to the right size, we need to
 250                  * shift right first.
 251                  */
 252                 switch(len) {
 253                 case 4:
 254                         rc = __put_user((u32)data, (u32 __user *)ubuf);
 255                         break;
 256                 case 2:
 257 #ifdef __LITTLE_ENDIAN__
 258                         data >>= 16;
 259 #endif
 260                         rc = __put_user((u16)data, (u16 __user *)ubuf);
 261                         break;
 262                 default:
 263 #ifdef __LITTLE_ENDIAN__
 264                         data >>= 24;
 265 #endif
 266                         rc = __put_user((u8)data, (u8 __user *)ubuf);
 267                         break;
 268                 }
 269                 if (rc)
 270                         return -EFAULT;
 271                 *ppos += len;
 272                 ubuf += len;
 273                 todo -= len;
 274         }
 275
 276         return count;
 277 }
 278
 279 static ssize_t lpc_debug_write(struct file *filp, const char __user *ubuf,
 280                                size_t count, loff_t *ppos)
 281 {
 282         struct lpc_debugfs_entry *lpc = filp->private_data;
 283         u32 data, pos, len, todo;
 284         int rc;
 285
 286         if (!access_ok(VERIFY_READ, ubuf, count))
 287                 return -EFAULT;
 288
 289         todo = count;
 290         while (todo) {
 291                 pos = *ppos;
 292
 293                 /*
 294                  * Select access size based on count and alignment and
 295                  * access type. IO and MEM only support byte acceses,
 296                  * FW supports all 3.
 297                  */
 298                 len = 1;
 299                 if (lpc->lpc_type == OPAL_LPC_FW) {
 300                         if (todo > 3 && (pos & 3) == 0)
 301                                 len = 4;
 302                         else if (todo > 1 && (pos & 1) == 0)
 303                                 len = 2;
 304                 }
 305
 306                 /*
 307                  * Similarly to the read case, we have some trickery here but
 308                  * it's different to handle. We need to pass the value to OPAL in
 309                  * a register whose layout depends on the access size. We want
 310                  * to reproduce the memory layout of the user, however we aren't
 311                  * doing a load from user and a store to another memory location
 312                  * which would achieve that. Here we pass the value to OPAL via
 313                  * a register which is expected to contain the "BE" interpretation
 314                  * of the byte sequence. IE: for a 32-bit access, byte 0 should be
 315                  * in the MSB. So here we *do* need to byteswap on LE.
 316                  *
 317                  *           User bytes:    LE "data"  OPAL "data"
 318                  *  32-bit:  B0 B1 B2 B3    B3B2B1B0   B0B1B2B3
 319                  *  16-bit:  B0 B1          0000B1B0   0000B0B1
 320                  *   8-bit:  B0             000000B0   000000B0
 321                  */
 322                 switch(len) {
 323                 case 4:
 324                         rc = __get_user(data, (u32 __user *)ubuf);
 325                         data = cpu_to_be32(data);
 326                         break;
 327                 case 2:
 328                         rc = __get_user(data, (u16 __user *)ubuf);
 329                         data = cpu_to_be16(data);
 330                         break;
 331                 default:
 332                         rc = __get_user(data, (u8 __user *)ubuf);
 333                         break;
 334                 }
 335                 if (rc)
 336                         return -EFAULT;
 337
 338                 rc = opal_lpc_write(opal_lpc_chip_id, lpc->lpc_type, pos,
 339                                     data, len);
 340                 if (rc)
 341                         return -ENXIO;
 342                 *ppos += len;
 343                 ubuf += len;
 344                 todo -= len;
 345         }
 346
 347         return count;
 348 }
 349
 350 static const struct file_operations lpc_fops = {
 351         .read =         lpc_debug_read,
 352         .write =        lpc_debug_write,
 353         .open =         simple_open,
 354         .llseek =       default_llseek,
 355 };
 356
 357 static int opal_lpc_debugfs_create_type(struct dentry *folder,
 358                                         const char *fname,
 359                                         enum OpalLPCAddressType type)
 360 {
 361         struct lpc_debugfs_entry *entry;
 362         entry = kzalloc(sizeof(*entry), GFP_KERNEL);
 363         if (!entry)
 364                 return -ENOMEM;
 365         entry->lpc_type = type;
 366         debugfs_create_file(fname, 0600, folder, entry, &lpc_fops);
 367         return 0;
 368 }
 369
 370 static int opal_lpc_init_debugfs(void)
 371 {
 372         struct dentry *root;
 373         int rc = 0;
 374
 375         if (opal_lpc_chip_id < 0)
 376                 return -ENODEV;
 377
 378         root = debugfs_create_dir("lpc", powerpc_debugfs_root);
 379
 380         rc |= opal_lpc_debugfs_create_type(root, "io", OPAL_LPC_IO);
 381         rc |= opal_lpc_debugfs_create_type(root, "mem", OPAL_LPC_MEM);
 382         rc |= opal_lpc_debugfs_create_type(root, "fw", OPAL_LPC_FW);
 383         return rc;
 384 }
 385 machine_device_initcall(powernv, opal_lpc_init_debugfs);
 386 #endif  /* CONFIG_DEBUG_FS */
 387
 388 void __init opal_lpc_init(void)
 389 {
 390         struct device_node *np;
 391
 392         /*
 393          * Look for a Power8 LPC bus tagged as "primary",
 394          * we currently support only one though the OPAL APIs
 395          * support any number.
 396          */
 397         for_each_compatible_node(np, NULL, "ibm,power8-lpc") {
 398                 if (!of_device_is_available(np))
 399                         continue;
 400                 if (!of_get_property(np, "primary", NULL))
 401                         continue;
 402                 opal_lpc_chip_id = of_get_ibm_chip_id(np);
 403                 break;
 404         }
 405         if (opal_lpc_chip_id < 0)
 406                 return;
 407
 408         /* Does it support direct mapping ? */
 409         if (of_get_property(np, "ranges", NULL)) {
 410                 pr_info("OPAL: Found memory mapped LPC bus on chip %d\n",
 411                         opal_lpc_chip_id);
 412                 isa_bridge_init_non_pci(np);
 413         } else {
 414                 pr_info("OPAL: Found non-mapped LPC bus on chip %d\n",
 415                         opal_lpc_chip_id);
 416
 417                 /* Setup special IO ops */
 418                 ppc_pci_io = opal_lpc_io;
 419                 isa_io_special = true;
 420         }
 421 }