arch/x86/kernel/iosf_mbi.c

   1 /*
   2  * IOSF-SB MailBox Interface Driver
   3  * Copyright (c) 2013, Intel Corporation.
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms and conditions of the GNU General Public License,
   7  * version 2, as published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  12  * more details.
  13  *
  14  *
  15  * The IOSF-SB is a fabric bus available on Atom based SOC's that uses a
  16  * mailbox interface (MBI) to communicate with mutiple devices. This
  17  * driver implements access to this interface for those platforms that can
  18  * enumerate the device using PCI.
  19  */
  20
  21 #include <linux/module.h>
  22 #include <linux/init.h>
  23 #include <linux/spinlock.h>
  24 #include <linux/pci.h>
  25 #include <linux/debugfs.h>
  26 #include <linux/capability.h>
  27
  28 #include <asm/iosf_mbi.h>
  29
  30 #define PCI_DEVICE_ID_BAYTRAIL          0x0F00
  31 #define PCI_DEVICE_ID_BRASWELL          0x2280
  32 #define PCI_DEVICE_ID_QUARK_X1000       0x0958
  33
  34 static DEFINE_SPINLOCK(iosf_mbi_lock);
  35
  36 static inline u32 iosf_mbi_form_mcr(u8 op, u8 port, u8 offset)
  37 {
  38         return (op << 24) | (port << 16) | (offset << 8) | MBI_ENABLE;
  39 }
  40
  41 static struct pci_dev *mbi_pdev;        /* one mbi device */
  42
  43 static int iosf_mbi_pci_read_mdr(u32 mcrx, u32 mcr, u32 *mdr)
  44 {
  45         int result;
  46
  47         if (!mbi_pdev)
  48                 return -ENODEV;
  49
  50         if (mcrx) {
  51                 result = pci_write_config_dword(mbi_pdev, MBI_MCRX_OFFSET,
  52                                                 mcrx);
  53                 if (result < 0)
  54                         goto fail_read;
  55         }
  56
  57         result = pci_write_config_dword(mbi_pdev, MBI_MCR_OFFSET, mcr);
  58         if (result < 0)
  59                 goto fail_read;
  60
  61         result = pci_read_config_dword(mbi_pdev, MBI_MDR_OFFSET, mdr);
  62         if (result < 0)
  63                 goto fail_read;
  64
  65         return 0;
  66
  67 fail_read:
  68         dev_err(&mbi_pdev->dev, "PCI config access failed with %d\n", result);
  69         return result;
  70 }
  71
  72 static int iosf_mbi_pci_write_mdr(u32 mcrx, u32 mcr, u32 mdr)
  73 {
  74         int result;
  75
  76         if (!mbi_pdev)
  77                 return -ENODEV;
  78
  79         result = pci_write_config_dword(mbi_pdev, MBI_MDR_OFFSET, mdr);
  80         if (result < 0)
  81                 goto fail_write;
  82
  83         if (mcrx) {
  84                 result = pci_write_config_dword(mbi_pdev, MBI_MCRX_OFFSET,
  85                                                 mcrx);
  86                 if (result < 0)
  87                         goto fail_write;
  88         }
  89
  90         result = pci_write_config_dword(mbi_pdev, MBI_MCR_OFFSET, mcr);
  91         if (result < 0)
  92                 goto fail_write;
  93
  94         return 0;
  95
  96 fail_write:
  97         dev_err(&mbi_pdev->dev, "PCI config access failed with %d\n", result);
  98         return result;
  99 }
 100
 101 int iosf_mbi_read(u8 port, u8 opcode, u32 offset, u32 *mdr)
 102 {
 103         u32 mcr, mcrx;
 104         unsigned long flags;
 105         int ret;
 106
 107         /*Access to the GFX unit is handled by GPU code */
 108         if (port == BT_MBI_UNIT_GFX) {
 109                 WARN_ON(1);
 110                 return -EPERM;
 111         }
 112
 113         mcr = iosf_mbi_form_mcr(opcode, port, offset & MBI_MASK_LO);
 114         mcrx = offset & MBI_MASK_HI;
 115
 116         spin_lock_irqsave(&iosf_mbi_lock, flags);
 117         ret = iosf_mbi_pci_read_mdr(mcrx, mcr, mdr);
 118         spin_unlock_irqrestore(&iosf_mbi_lock, flags);
 119
 120         return ret;
 121 }
 122 EXPORT_SYMBOL(iosf_mbi_read);
 123
 124 int iosf_mbi_write(u8 port, u8 opcode, u32 offset, u32 mdr)
 125 {
 126         u32 mcr, mcrx;
 127         unsigned long flags;
 128         int ret;
 129
 130         /*Access to the GFX unit is handled by GPU code */
 131         if (port == BT_MBI_UNIT_GFX) {
 132                 WARN_ON(1);
 133                 return -EPERM;
 134         }
 135
 136         mcr = iosf_mbi_form_mcr(opcode, port, offset & MBI_MASK_LO);
 137         mcrx = offset & MBI_MASK_HI;
 138
 139         spin_lock_irqsave(&iosf_mbi_lock, flags);
 140         ret = iosf_mbi_pci_write_mdr(mcrx, mcr, mdr);
 141         spin_unlock_irqrestore(&iosf_mbi_lock, flags);
 142
 143         return ret;
 144 }
 145 EXPORT_SYMBOL(iosf_mbi_write);
 146
 147 int iosf_mbi_modify(u8 port, u8 opcode, u32 offset, u32 mdr, u32 mask)
 148 {
 149         u32 mcr, mcrx;
 150         u32 value;
 151         unsigned long flags;
 152         int ret;
 153
 154         /*Access to the GFX unit is handled by GPU code */
 155         if (port == BT_MBI_UNIT_GFX) {
 156                 WARN_ON(1);
 157                 return -EPERM;
 158         }
 159
 160         mcr = iosf_mbi_form_mcr(opcode, port, offset & MBI_MASK_LO);
 161         mcrx = offset & MBI_MASK_HI;
 162
 163         spin_lock_irqsave(&iosf_mbi_lock, flags);
 164
 165         /* Read current mdr value */
 166         ret = iosf_mbi_pci_read_mdr(mcrx, mcr & MBI_RD_MASK, &value);
 167         if (ret < 0) {
 168                 spin_unlock_irqrestore(&iosf_mbi_lock, flags);
 169                 return ret;
 170         }
 171
 172         /* Apply mask */
 173         value &= ~mask;
 174         mdr &= mask;
 175         value |= mdr;
 176
 177         /* Write back */
 178         ret = iosf_mbi_pci_write_mdr(mcrx, mcr | MBI_WR_MASK, value);
 179
 180         spin_unlock_irqrestore(&iosf_mbi_lock, flags);
 181
 182         return ret;
 183 }
 184 EXPORT_SYMBOL(iosf_mbi_modify);
 185
 186 bool iosf_mbi_available(void)
 187 {
 188         /* Mbi isn't hot-pluggable. No remove routine is provided */
 189         return mbi_pdev;
 190 }
 191 EXPORT_SYMBOL(iosf_mbi_available);
 192
 193 #ifdef CONFIG_IOSF_MBI_DEBUG
 194 static u32      dbg_mdr;
 195 static u32      dbg_mcr;
 196 static u32      dbg_mcrx;
 197
 198 static int mcr_get(void *data, u64 *val)
 199 {
 200         *val = *(u32 *)data;
 201         return 0;
 202 }
 203
 204 static int mcr_set(void *data, u64 val)
 205 {
 206         u8 command = ((u32)val & 0xFF000000) >> 24,
 207            port    = ((u32)val & 0x00FF0000) >> 16,
 208            offset  = ((u32)val & 0x0000FF00) >> 8;
 209         int err;
 210
 211         *(u32 *)data = val;
 212
 213         if (!capable(CAP_SYS_RAWIO))
 214                 return -EACCES;
 215
 216         if (command & 1u)
 217                 err = iosf_mbi_write(port,
 218                                command,
 219                                dbg_mcrx | offset,
 220                                dbg_mdr);
 221         else
 222                 err = iosf_mbi_read(port,
 223                               command,
 224                               dbg_mcrx | offset,
 225                               &dbg_mdr);
 226
 227         return err;
 228 }
 229 DEFINE_SIMPLE_ATTRIBUTE(iosf_mcr_fops, mcr_get, mcr_set , "%llx\n");
 230
 231 static struct dentry *iosf_dbg;
 232
 233 static void iosf_sideband_debug_init(void)
 234 {
 235         struct dentry *d;
 236
 237         iosf_dbg = debugfs_create_dir("iosf_sb", NULL);
 238         if (IS_ERR_OR_NULL(iosf_dbg))
 239                 return;
 240
 241         /* mdr */
 242         d = debugfs_create_x32("mdr", 0660, iosf_dbg, &dbg_mdr);
 243         if (IS_ERR_OR_NULL(d))
 244                 goto cleanup;
 245
 246         /* mcrx */
 247         debugfs_create_x32("mcrx", 0660, iosf_dbg, &dbg_mcrx);
 248         if (IS_ERR_OR_NULL(d))
 249                 goto cleanup;
 250
 251         /* mcr - initiates mailbox tranaction */
 252         debugfs_create_file("mcr", 0660, iosf_dbg, &dbg_mcr, &iosf_mcr_fops);
 253         if (IS_ERR_OR_NULL(d))
 254                 goto cleanup;
 255
 256         return;
 257
 258 cleanup:
 259         debugfs_remove_recursive(d);
 260 }
 261
 262 static void iosf_debugfs_init(void)
 263 {
 264         iosf_sideband_debug_init();
 265 }
 266
 267 static void iosf_debugfs_remove(void)
 268 {
 269         debugfs_remove_recursive(iosf_dbg);
 270 }
 271 #else
 272 static inline void iosf_debugfs_init(void) { }
 273 static inline void iosf_debugfs_remove(void) { }
 274 #endif /* CONFIG_IOSF_MBI_DEBUG */
 275
 276 static int iosf_mbi_probe(struct pci_dev *pdev,
 277                           const struct pci_device_id *unused)
 278 {
 279         int ret;
 280
 281         ret = pci_enable_device(pdev);
 282         if (ret < 0) {
 283                 dev_err(&pdev->dev, "error: could not enable device\n");
 284                 return ret;
 285         }
 286
 287         mbi_pdev = pci_dev_get(pdev);
 288         return 0;
 289 }
 290
 291 static const struct pci_device_id iosf_mbi_pci_ids[] = {
 292         { PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_BAYTRAIL) },
 293         { PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_BRASWELL) },
 294         { PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_QUARK_X1000) },
 295         { 0, },
 296 };
 297 MODULE_DEVICE_TABLE(pci, iosf_mbi_pci_ids);
 298
 299 static struct pci_driver iosf_mbi_pci_driver = {
 300         .name           = "iosf_mbi_pci",
 301         .probe          = iosf_mbi_probe,
 302         .id_table       = iosf_mbi_pci_ids,
 303 };
 304
 305 static int __init iosf_mbi_init(void)
 306 {
 307         iosf_debugfs_init();
 308
 309         return pci_register_driver(&iosf_mbi_pci_driver);
 310 }
 311
 312 static void __exit iosf_mbi_exit(void)
 313 {
 314         iosf_debugfs_remove();
 315
 316         pci_unregister_driver(&iosf_mbi_pci_driver);
 317         if (mbi_pdev) {
 318                 pci_dev_put(mbi_pdev);
 319                 mbi_pdev = NULL;
 320         }
 321 }
 322
 323 module_init(iosf_mbi_init);
 324 module_exit(iosf_mbi_exit);
 325
 326 MODULE_AUTHOR("David E. Box <david.e.box@linux.intel.com>");
 327 MODULE_DESCRIPTION("IOSF Mailbox Interface accessor");
 328 MODULE_LICENSE("GPL v2");