drivers/dma/ioat/dca.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Intel I/OAT DMA Linux driver
   4  * Copyright(c) 2007 - 2009 Intel Corporation.
   5  */
   6
   7 #include <linux/kernel.h>
   8 #include <linux/pci.h>
   9 #include <linux/smp.h>
  10 #include <linux/interrupt.h>
  11 #include <linux/dca.h>
  12
  13 /* either a kernel change is needed, or we need something like this in kernel */
  14 #ifndef CONFIG_SMP
  15 #include <asm/smp.h>
  16 #undef cpu_physical_id
  17 #define cpu_physical_id(cpu) (cpuid_ebx(1) >> 24)
  18 #endif
  19
  20 #include "dma.h"
  21 #include "registers.h"
  22
  23 /*
  24  * Bit 7 of a tag map entry is the "valid" bit, if it is set then bits 0:6
  25  * contain the bit number of the APIC ID to map into the DCA tag.  If the valid
  26  * bit is not set, then the value must be 0 or 1 and defines the bit in the tag.
  27  */
  28 #define DCA_TAG_MAP_VALID 0x80
  29
  30 #define DCA3_TAG_MAP_BIT_TO_INV 0x80
  31 #define DCA3_TAG_MAP_BIT_TO_SEL 0x40
  32 #define DCA3_TAG_MAP_LITERAL_VAL 0x1
  33
  34 #define DCA_TAG_MAP_MASK 0xDF
  35
  36 /* expected tag map bytes for I/OAT ver.2 */
  37 #define DCA2_TAG_MAP_BYTE0 0x80
  38 #define DCA2_TAG_MAP_BYTE1 0x0
  39 #define DCA2_TAG_MAP_BYTE2 0x81
  40 #define DCA2_TAG_MAP_BYTE3 0x82
  41 #define DCA2_TAG_MAP_BYTE4 0x82
  42
  43 /*
  44  * "Legacy" DCA systems do not implement the DCA register set in the
  45  * I/OAT device.  Software needs direct support for their tag mappings.
  46  */
  47
  48 #define APICID_BIT(x)           (DCA_TAG_MAP_VALID | (x))
  49 #define IOAT_TAG_MAP_LEN        8
  50
  51 /* pack PCI B/D/F into a u16 */
  52 static inline u16 dcaid_from_pcidev(struct pci_dev *pci)
  53 {
  54         return (pci->bus->number << 8) | pci->devfn;
  55 }
  56
  57 static int dca_enabled_in_bios(struct pci_dev *pdev)
  58 {
  59         /* CPUID level 9 returns DCA configuration */
  60         /* Bit 0 indicates DCA enabled by the BIOS */
  61         unsigned long cpuid_level_9;
  62         int res;
  63
  64         cpuid_level_9 = cpuid_eax(9);
  65         res = test_bit(0, &cpuid_level_9);
  66         if (!res)
  67                 dev_dbg(&pdev->dev, "DCA is disabled in BIOS\n");
  68
  69         return res;
  70 }
  71
  72 int system_has_dca_enabled(struct pci_dev *pdev)
  73 {
  74         if (boot_cpu_has(X86_FEATURE_DCA))
  75                 return dca_enabled_in_bios(pdev);
  76
  77         dev_dbg(&pdev->dev, "boot cpu doesn't have X86_FEATURE_DCA\n");
  78         return 0;
  79 }
  80
  81 struct ioat_dca_slot {
  82         struct pci_dev *pdev;   /* requester device */
  83         u16 rid;                /* requester id, as used by IOAT */
  84 };
  85
  86 #define IOAT_DCA_MAX_REQ 6
  87 #define IOAT3_DCA_MAX_REQ 2
  88
  89 struct ioat_dca_priv {
  90         void __iomem            *iobase;
  91         void __iomem            *dca_base;
  92         int                      max_requesters;
  93         int                      requester_count;
  94         u8                       tag_map[IOAT_TAG_MAP_LEN];
  95         struct ioat_dca_slot     req_slots[];
  96 };
  97
  98 static int ioat_dca_dev_managed(struct dca_provider *dca,
  99                                 struct device *dev)
 100 {
 101         struct ioat_dca_priv *ioatdca = dca_priv(dca);
 102         struct pci_dev *pdev;
 103         int i;
 104
 105         pdev = to_pci_dev(dev);
 106         for (i = 0; i < ioatdca->max_requesters; i++) {
 107                 if (ioatdca->req_slots[i].pdev == pdev)
 108                         return 1;
 109         }
 110         return 0;
 111 }
 112
 113 static int ioat_dca_add_requester(struct dca_provider *dca, struct device *dev)
 114 {
 115         struct ioat_dca_priv *ioatdca = dca_priv(dca);
 116         struct pci_dev *pdev;
 117         int i;
 118         u16 id;
 119         u16 global_req_table;
 120
 121         /* This implementation only supports PCI-Express */
 122         if (!dev_is_pci(dev))
 123                 return -ENODEV;
 124         pdev = to_pci_dev(dev);
 125         id = dcaid_from_pcidev(pdev);
 126
 127         if (ioatdca->requester_count == ioatdca->max_requesters)
 128                 return -ENODEV;
 129
 130         for (i = 0; i < ioatdca->max_requesters; i++) {
 131                 if (ioatdca->req_slots[i].pdev == NULL) {
 132                         /* found an empty slot */
 133                         ioatdca->requester_count++;
 134                         ioatdca->req_slots[i].pdev = pdev;
 135                         ioatdca->req_slots[i].rid = id;
 136                         global_req_table =
 137                               readw(ioatdca->dca_base + IOAT3_DCA_GREQID_OFFSET);
 138                         writel(id | IOAT_DCA_GREQID_VALID,
 139                                ioatdca->iobase + global_req_table + (i * 4));
 140                         return i;
 141                 }
 142         }
 143         /* Error, ioatdma->requester_count is out of whack */
 144         return -EFAULT;
 145 }
 146
 147 static int ioat_dca_remove_requester(struct dca_provider *dca,
 148                                       struct device *dev)
 149 {
 150         struct ioat_dca_priv *ioatdca = dca_priv(dca);
 151         struct pci_dev *pdev;
 152         int i;
 153         u16 global_req_table;
 154
 155         /* This implementation only supports PCI-Express */
 156         if (!dev_is_pci(dev))
 157                 return -ENODEV;
 158         pdev = to_pci_dev(dev);
 159
 160         for (i = 0; i < ioatdca->max_requesters; i++) {
 161                 if (ioatdca->req_slots[i].pdev == pdev) {
 162                         global_req_table =
 163                               readw(ioatdca->dca_base + IOAT3_DCA_GREQID_OFFSET);
 164                         writel(0, ioatdca->iobase + global_req_table + (i * 4));
 165                         ioatdca->req_slots[i].pdev = NULL;
 166                         ioatdca->req_slots[i].rid = 0;
 167                         ioatdca->requester_count--;
 168                         return i;
 169                 }
 170         }
 171         return -ENODEV;
 172 }
 173
 174 static u8 ioat_dca_get_tag(struct dca_provider *dca,
 175                             struct device *dev,
 176                             int cpu)
 177 {
 178         u8 tag;
 179
 180         struct ioat_dca_priv *ioatdca = dca_priv(dca);
 181         int i, apic_id, bit, value;
 182         u8 entry;
 183
 184         tag = 0;
 185         apic_id = cpu_physical_id(cpu);
 186
 187         for (i = 0; i < IOAT_TAG_MAP_LEN; i++) {
 188                 entry = ioatdca->tag_map[i];
 189                 if (entry & DCA3_TAG_MAP_BIT_TO_SEL) {
 190                         bit = entry &
 191                                 ~(DCA3_TAG_MAP_BIT_TO_SEL | DCA3_TAG_MAP_BIT_TO_INV);
 192                         value = (apic_id & (1 << bit)) ? 1 : 0;
 193                 } else if (entry & DCA3_TAG_MAP_BIT_TO_INV) {
 194                         bit = entry & ~DCA3_TAG_MAP_BIT_TO_INV;
 195                         value = (apic_id & (1 << bit)) ? 0 : 1;
 196                 } else {
 197                         value = (entry & DCA3_TAG_MAP_LITERAL_VAL) ? 1 : 0;
 198                 }
 199                 tag |= (value << i);
 200         }
 201
 202         return tag;
 203 }
 204
 205 static const struct dca_ops ioat_dca_ops = {
 206         .add_requester          = ioat_dca_add_requester,
 207         .remove_requester       = ioat_dca_remove_requester,
 208         .get_tag                = ioat_dca_get_tag,
 209         .dev_managed            = ioat_dca_dev_managed,
 210 };
 211
 212 static int ioat_dca_count_dca_slots(void *iobase, u16 dca_offset)
 213 {
 214         int slots = 0;
 215         u32 req;
 216         u16 global_req_table;
 217
 218         global_req_table = readw(iobase + dca_offset + IOAT3_DCA_GREQID_OFFSET);
 219         if (global_req_table == 0)
 220                 return 0;
 221
 222         do {
 223                 req = readl(iobase + global_req_table + (slots * sizeof(u32)));
 224                 slots++;
 225         } while ((req & IOAT_DCA_GREQID_LASTID) == 0);
 226
 227         return slots;
 228 }
 229
 230 static inline int dca3_tag_map_invalid(u8 *tag_map)
 231 {
 232         /*
 233          * If the tag map is not programmed by the BIOS the default is:
 234          * 0x80 0x80 0x80 0x80 0x80 0x00 0x00 0x00
 235          *
 236          * This an invalid map and will result in only 2 possible tags
 237          * 0x1F and 0x00.  0x00 is an invalid DCA tag so we know that
 238          * this entire definition is invalid.
 239          */
 240         return ((tag_map[0] == DCA_TAG_MAP_VALID) &&
 241                 (tag_map[1] == DCA_TAG_MAP_VALID) &&
 242                 (tag_map[2] == DCA_TAG_MAP_VALID) &&
 243                 (tag_map[3] == DCA_TAG_MAP_VALID) &&
 244                 (tag_map[4] == DCA_TAG_MAP_VALID));
 245 }
 246
 247 struct dca_provider *ioat_dca_init(struct pci_dev *pdev, void __iomem *iobase)
 248 {
 249         struct dca_provider *dca;
 250         struct ioat_dca_priv *ioatdca;
 251         int slots;
 252         int i;
 253         int err;
 254         u16 dca_offset;
 255         u16 csi_fsb_control;
 256         u16 pcie_control;
 257         u8 bit;
 258
 259         union {
 260                 u64 full;
 261                 struct {
 262                         u32 low;
 263                         u32 high;
 264                 };
 265         } tag_map;
 266
 267         if (!system_has_dca_enabled(pdev))
 268                 return NULL;
 269
 270         dca_offset = readw(iobase + IOAT_DCAOFFSET_OFFSET);
 271         if (dca_offset == 0)
 272                 return NULL;
 273
 274         slots = ioat_dca_count_dca_slots(iobase, dca_offset);
 275         if (slots == 0)
 276                 return NULL;
 277
 278         dca = alloc_dca_provider(&ioat_dca_ops,
 279                                  struct_size(ioatdca, req_slots, slots));
 280         if (!dca)
 281                 return NULL;
 282
 283         ioatdca = dca_priv(dca);
 284         ioatdca->iobase = iobase;
 285         ioatdca->dca_base = iobase + dca_offset;
 286         ioatdca->max_requesters = slots;
 287
 288         /* some bios might not know to turn these on */
 289         csi_fsb_control = readw(ioatdca->dca_base + IOAT3_CSI_CONTROL_OFFSET);
 290         if ((csi_fsb_control & IOAT3_CSI_CONTROL_PREFETCH) == 0) {
 291                 csi_fsb_control |= IOAT3_CSI_CONTROL_PREFETCH;
 292                 writew(csi_fsb_control,
 293                        ioatdca->dca_base + IOAT3_CSI_CONTROL_OFFSET);
 294         }
 295         pcie_control = readw(ioatdca->dca_base + IOAT3_PCI_CONTROL_OFFSET);
 296         if ((pcie_control & IOAT3_PCI_CONTROL_MEMWR) == 0) {
 297                 pcie_control |= IOAT3_PCI_CONTROL_MEMWR;
 298                 writew(pcie_control,
 299                        ioatdca->dca_base + IOAT3_PCI_CONTROL_OFFSET);
 300         }
 301
 302
 303         /* TODO version, compatibility and configuration checks */
 304
 305         /* copy out the APIC to DCA tag map */
 306         tag_map.low =
 307                 readl(ioatdca->dca_base + IOAT3_APICID_TAG_MAP_OFFSET_LOW);
 308         tag_map.high =
 309                 readl(ioatdca->dca_base + IOAT3_APICID_TAG_MAP_OFFSET_HIGH);
 310         for (i = 0; i < 8; i++) {
 311                 bit = tag_map.full >> (8 * i);
 312                 ioatdca->tag_map[i] = bit & DCA_TAG_MAP_MASK;
 313         }
 314
 315         if (dca3_tag_map_invalid(ioatdca->tag_map)) {
 316                 add_taint(TAINT_FIRMWARE_WORKAROUND, LOCKDEP_STILL_OK);
 317                 pr_warn_once("%s %s: APICID_TAG_MAP set incorrectly by BIOS, disabling DCA\n",
 318                              dev_driver_string(&pdev->dev),
 319                              dev_name(&pdev->dev));
 320                 free_dca_provider(dca);
 321                 return NULL;
 322         }
 323
 324         err = register_dca_provider(dca, &pdev->dev);
 325         if (err) {
 326                 free_dca_provider(dca);
 327                 return NULL;
 328         }
 329
 330         return dca;
 331 }