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