Add option to expose additional fixed-sized partition starting
from the beginning of storage.
Xe driver can request this partition exposure if firmware or hardware
have detected failure that may involve corrupted partition table.
Fixed-sized partition allows full storage re-write in this situation.

Signed-off-by: Alexander Usyskin <[email protected]>
---
 drivers/mtd/devices/mtd_intel_dg.c | 80 +++++++++++++++++++++++++++-----------
 include/linux/intel_dg_nvm_aux.h   |  1 +
 2 files changed, 59 insertions(+), 22 deletions(-)

diff --git a/drivers/mtd/devices/mtd_intel_dg.c 
b/drivers/mtd/devices/mtd_intel_dg.c
index f2fa8f68d190..d11ddc687c4a 100644
--- a/drivers/mtd/devices/mtd_intel_dg.c
+++ b/drivers/mtd/devices/mtd_intel_dg.c
@@ -31,6 +31,7 @@ struct intel_dg_nvm {
        void __iomem *base;
        void __iomem *base2;
        bool non_posted_erase;
+       bool survivability_enabled;
 
        size_t size;
        unsigned int nregions;
@@ -205,6 +206,13 @@ static unsigned int idg_nvm_get_region(const struct 
intel_dg_nvm *nvm, loff_t fr
 {
        unsigned int i;
 
+       /*
+        * When survivability region is enabled it positioned on index 0 and 
has region_id = 0
+        * Region 0 is special, via this region whole device memory can be 
accessed.
+        */
+       if (nvm->survivability_enabled)
+               return 0;
+
        for (i = 0; i < nvm->nregions; i++) {
                if ((nvm->regions[i].offset + nvm->regions[i].size - 1) >= from 
&&
                    nvm->regions[i].offset <= from &&
@@ -443,32 +451,39 @@ static int intel_dg_nvm_init(struct intel_dg_nvm *nvm, 
struct device *device,
                u32 address, base, limit, region;
                u8 id = nvm->regions[i].id;
 
-               address = NVM_FLREG(id);
-               region = idg_nvm_read32(nvm, address);
+               if (nvm->regions[i].size) { /* pre-defined survivability region 
*/
+                       limit = nvm->regions[i].offset + nvm->regions[i].size - 
1;
 
-               base = FIELD_GET(NVM_FREG_BASE_MASK, region) << 
NVM_FREG_ADDR_SHIFT;
-               limit = (FIELD_GET(NVM_FREG_ADDR_MASK, region) << 
NVM_FREG_ADDR_SHIFT) |
-                       NVM_FREG_MIN_REGION_SIZE;
+                       if (nvm->size < limit)
+                               nvm->size = limit;
+               } else {
+                       address = NVM_FLREG(id);
+                       region = idg_nvm_read32(nvm, address);
 
-               dev_dbg(device, "[%d] %s: region: 0x%08X base: 0x%08x limit: 
0x%08x\n",
-                       id, nvm->regions[i].name, region, base, limit);
+                       base = FIELD_GET(NVM_FREG_BASE_MASK, region) << 
NVM_FREG_ADDR_SHIFT;
+                       limit = (FIELD_GET(NVM_FREG_ADDR_MASK, region) << 
NVM_FREG_ADDR_SHIFT) |
+                               NVM_FREG_MIN_REGION_SIZE;
 
-               if (base >= limit || (i > 0 && limit == 0)) {
-                       dev_dbg(device, "[%d] %s: disabled\n",
-                               id, nvm->regions[i].name);
-                       nvm->regions[i].is_readable = 0;
-                       continue;
-               }
+                       dev_dbg(device, "[%d] %s: region: 0x%08X base: 0x%08x 
limit: 0x%08x\n",
+                               id, nvm->regions[i].name, region, base, limit);
 
-               if (nvm->size < limit)
-                       nvm->size = limit;
+                       if (base >= limit || (i > 0 && limit == 0)) {
+                               dev_dbg(device, "[%d] %s: disabled\n",
+                                       id, nvm->regions[i].name);
+                               nvm->regions[i].is_readable = 0;
+                               continue;
+                       }
 
-               nvm->regions[i].offset = base;
-               nvm->regions[i].size = limit - base + 1;
-               /* No write access to descriptor; mask it out*/
-               nvm->regions[i].is_writable = 
idg_nvm_region_writable(access_map, id);
+                       if (nvm->size < limit)
+                               nvm->size = limit;
 
-               nvm->regions[i].is_readable = 
idg_nvm_region_readable(access_map, id);
+                       nvm->regions[i].offset = base;
+                       nvm->regions[i].size = limit - base + 1;
+                       /* No write access to descriptor; mask it out*/
+                       nvm->regions[i].is_writable = 
idg_nvm_region_writable(access_map, id);
+
+                       nvm->regions[i].is_readable = 
idg_nvm_region_readable(access_map, id);
+               }
                dev_dbg(device, "Registered, %s id=%d offset=%lld size=%lld 
rd=%d wr=%d\n",
                        nvm->regions[i].name,
                        nvm->regions[i].id,
@@ -748,7 +763,7 @@ static int intel_dg_mtd_probe(struct auxiliary_device 
*aux_dev,
        struct intel_dg_nvm *nvm;
        struct device *device;
        unsigned int nregions;
-       unsigned int i, n;
+       unsigned int i, n = 0;
        int ret;
 
        device = &aux_dev->dev;
@@ -764,6 +779,9 @@ static int intel_dg_mtd_probe(struct auxiliary_device 
*aux_dev,
                return -ENODEV;
        }
 
+       if (invm->survivability_size)
+               nregions++;
+
        nvm = kzalloc_flex(*nvm, regions, nregions);
        if (!nvm)
                return -ENOMEM;
@@ -771,8 +789,26 @@ static int intel_dg_mtd_probe(struct auxiliary_device 
*aux_dev,
        kref_init(&nvm->refcnt);
        mutex_init(&nvm->lock);
        nvm->nregions = nregions;
+       nvm->survivability_enabled = !!invm->survivability_size;
+
+       if (invm->survivability_size) { /* this partition should be at idx 0 */
+               char *name = kasprintf(GFP_KERNEL, "%s.%s",
+                                      dev_name(&aux_dev->dev), "DATA");
+               if (!name) {
+                       ret = -ENOMEM;
+                       goto err_norpm;
+               }
+
+               nvm->regions[n].name = name;
+               nvm->regions[n].id = 0;
+               nvm->regions[n].offset  = 0;
+               nvm->regions[n].size = invm->survivability_size;
+               nvm->regions[n].is_readable = true;
+               nvm->regions[n].is_writable = true;
+               n++;
+       }
 
-       for (n = 0, i = 0; i < INTEL_DG_NVM_REGIONS; i++) {
+       for (i = 0; i < INTEL_DG_NVM_REGIONS; i++) {
                if (!invm->regions[i].name)
                        continue;
 
diff --git a/include/linux/intel_dg_nvm_aux.h b/include/linux/intel_dg_nvm_aux.h
index 625d46a6b96e..84b5b6e0c4ea 100644
--- a/include/linux/intel_dg_nvm_aux.h
+++ b/include/linux/intel_dg_nvm_aux.h
@@ -21,6 +21,7 @@ struct intel_dg_nvm_dev {
        struct auxiliary_device aux_dev;
        bool writable_override;
        bool non_posted_erase;
+       size_t survivability_size;
        struct resource bar;
        struct resource bar2;
        const struct intel_dg_nvm_region *regions;

-- 
2.53.0

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