[PATCH v2 1/2] mtd: mtd_intel_dg: add survivability partition

[Alexander Usyskin]

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 <alexander.usyskin@xxxxxxxxx>
---
 drivers/mtd/devices/mtd_intel_dg.c | 66 +++++++++++++++++++++++++++++---------
 include/linux/intel_dg_nvm_aux.h   |  1 +
 2 files changed, 51 insertions(+), 16 deletions(-)

diff --git a/drivers/mtd/devices/mtd_intel_dg.c b/drivers/mtd/devices/mtd_intel_dg.c
index a566e86eb5e3..962f30779c51 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;
@@ -430,6 +431,16 @@ static int intel_dg_nvm_init(struct intel_dg_nvm *nvm, struct device *device,
 	/* clean error register, previous errors are ignored */
 	idg_nvm_error(nvm);
 
+
+	if (nvm->survivability_enabled) {
+		nvm->size = nvm->regions[0].offset + nvm->regions[0].size - 1;
+		dev_dbg(device, "Registered survivability region %s size=%lld\n",
+			nvm->regions[0].name,
+			nvm->regions[0].size);
+		n = 1;
+		goto out;
+	}
+
 	ret = idg_nvm_is_valid(nvm);
 	if (ret) {
 		dev_err(device, "The MEM is not valid %d\n", ret);
@@ -481,6 +492,7 @@ static int intel_dg_nvm_init(struct intel_dg_nvm *nvm, struct device *device,
 			n++;
 	}
 
+out:
 	nvm->non_posted_erase = non_posted_erase;
 
 	dev_dbg(device, "Registered %d regions\n", n);
@@ -753,15 +765,19 @@ static int intel_dg_mtd_probe(struct auxiliary_device *aux_dev,
 
 	device = &aux_dev->dev;
 
-	/* count available regions */
-	for (nregions = 0, i = 0; i < INTEL_DG_NVM_REGIONS; i++) {
-		if (invm->regions[i].name)
-			nregions++;
-	}
+	if (invm->survivability_size) {
+		nregions = 1;
+	} else {
+		/* count available regions */
+		for (nregions = 0, i = 0; i < INTEL_DG_NVM_REGIONS; i++) {
+			if (invm->regions[i].name)
+				nregions++;
+		}
 
-	if (!nregions) {
-		dev_err(device, "no regions defined\n");
-		return -ENODEV;
+		if (!nregions) {
+			dev_err(device, "no regions defined\n");
+			return -ENODEV;
+		}
 	}
 
 	nvm = kzalloc_flex(*nvm, regions, nregions);
@@ -771,21 +787,39 @@ 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;
 
-	for (n = 0, i = 0; i < INTEL_DG_NVM_REGIONS; i++) {
-		if (!invm->regions[i].name)
-			continue;
-
+	if (invm->survivability_size) { /* survivability partition */
 		char *name = kasprintf(GFP_KERNEL, "%s.%s",
-				       dev_name(&aux_dev->dev), invm->regions[i].name);
+				       dev_name(&aux_dev->dev), "DATA");
 		if (!name) {
 			ret = -ENOMEM;
 			goto err_norpm;
 		}
 
-		nvm->regions[n].name = name;
-		nvm->regions[n].id = i;
-		n++;
+		nvm->regions[0].name = name;
+		nvm->regions[0].id = 0;
+		nvm->regions[0].offset  = 0;
+		nvm->regions[0].size = invm->survivability_size;
+		nvm->regions[0].is_readable = true;
+		nvm->regions[0].is_writable = true;
+		n = 1;
+	} else {
+		for (n = 0, i = 0; i < INTEL_DG_NVM_REGIONS; i++) {
+			if (!invm->regions[i].name)
+				continue;
+
+			char *name = kasprintf(GFP_KERNEL, "%s.%s",
+					       dev_name(&aux_dev->dev), invm->regions[i].name);
+			if (!name) {
+				ret = -ENOMEM;
+				goto err_norpm;
+			}
+
+			nvm->regions[n].name = name;
+			nvm->regions[n].id = i;
+			n++;
+		}
 	}
 
 	ret = devm_pm_runtime_enable(device);
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