Register the on-die nvm device with the mtd subsystem.
Refcount nvm object on _get and _put mtd callbacks.
For erase operation address and size should be 4K aligned.
For write operation address and size has to be 4bytes aligned.

CC: Rodrigo Vivi <rodrigo.v...@intel.com>
CC: Lucas De Marchi <lucas.demar...@intel.com>
Acked-by: Miquel Raynal <miquel.ray...@bootlin.com>
Co-developed-by: Tomas Winkler <tom...@gmail.com>
Signed-off-by: Tomas Winkler <tom...@gmail.com>
Co-developed-by: Vitaly Lubart <lubvi...@gmail.com>
Signed-off-by: Vitaly Lubart <lubvi...@gmail.com>
Signed-off-by: Alexander Usyskin <alexander.usys...@intel.com>
---
 drivers/mtd/devices/mtd_intel_dg.c | 230 ++++++++++++++++++++++++++++-
 1 file changed, 226 insertions(+), 4 deletions(-)

diff --git a/drivers/mtd/devices/mtd_intel_dg.c 
b/drivers/mtd/devices/mtd_intel_dg.c
index 6f67cf966d05..4023f2ebc344 100644
--- a/drivers/mtd/devices/mtd_intel_dg.c
+++ b/drivers/mtd/devices/mtd_intel_dg.c
@@ -5,6 +5,7 @@
 
 #include <linux/bitfield.h>
 #include <linux/bits.h>
+#include <linux/cleanup.h>
 #include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/intel_dg_nvm_aux.h>
@@ -12,6 +13,8 @@
 #include <linux/io-64-nonatomic-lo-hi.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/partitions.h>
 #include <linux/string.h>
 #include <linux/slab.h>
 #include <linux/sizes.h>
@@ -19,6 +22,8 @@
 
 struct intel_dg_nvm {
        struct kref refcnt;
+       struct mtd_info mtd;
+       struct mutex lock; /* region access lock */
        void __iomem *base;
        size_t size;
        unsigned int nregions;
@@ -177,7 +182,6 @@ static int idg_nvm_is_valid(struct intel_dg_nvm *nvm)
        return 0;
 }
 
-__maybe_unused
 static unsigned int idg_nvm_get_region(const struct intel_dg_nvm *nvm, loff_t 
from)
 {
        unsigned int i;
@@ -209,7 +213,6 @@ static ssize_t idg_nvm_rewrite_partial(struct intel_dg_nvm 
*nvm, loff_t to,
        return len;
 }
 
-__maybe_unused
 static ssize_t idg_write(struct intel_dg_nvm *nvm, u8 region,
                         loff_t to, size_t len, const unsigned char *buf)
 {
@@ -266,7 +269,6 @@ static ssize_t idg_write(struct intel_dg_nvm *nvm, u8 
region,
        return len;
 }
 
-__maybe_unused
 static ssize_t idg_read(struct intel_dg_nvm *nvm, u8 region,
                        loff_t from, size_t len, unsigned char *buf)
 {
@@ -325,7 +327,6 @@ static ssize_t idg_read(struct intel_dg_nvm *nvm, u8 region,
        return len;
 }
 
-__maybe_unused
 static ssize_t
 idg_erase(struct intel_dg_nvm *nvm, u8 region, loff_t from, u64 len, u64 
*fail_addr)
 {
@@ -414,6 +415,147 @@ static int intel_dg_nvm_init(struct intel_dg_nvm *nvm, 
struct device *device)
        return n;
 }
 
+static int intel_dg_mtd_erase(struct mtd_info *mtd, struct erase_info *info)
+{
+       struct intel_dg_nvm *nvm = mtd->priv;
+       unsigned int idx;
+       u8 region;
+       u64 addr;
+       ssize_t bytes;
+       loff_t from;
+       size_t len;
+       size_t total_len;
+
+       if (WARN_ON(!nvm))
+               return -EINVAL;
+
+       if (!IS_ALIGNED(info->addr, SZ_4K) || !IS_ALIGNED(info->len, SZ_4K)) {
+               dev_err(&mtd->dev, "unaligned erase %llx %llx\n",
+                       info->addr, info->len);
+               info->fail_addr = MTD_FAIL_ADDR_UNKNOWN;
+               return -EINVAL;
+       }
+
+       total_len = info->len;
+       addr = info->addr;
+
+       guard(mutex)(&nvm->lock);
+
+       while (total_len > 0) {
+               if (!IS_ALIGNED(addr, SZ_4K) || !IS_ALIGNED(total_len, SZ_4K)) {
+                       dev_err(&mtd->dev, "unaligned erase %llx %zx\n", addr, 
total_len);
+                       info->fail_addr = addr;
+                       return -ERANGE;
+               }
+
+               idx = idg_nvm_get_region(nvm, addr);
+               if (idx >= nvm->nregions) {
+                       dev_err(&mtd->dev, "out of range");
+                       info->fail_addr = MTD_FAIL_ADDR_UNKNOWN;
+                       return -ERANGE;
+               }
+
+               from = addr - nvm->regions[idx].offset;
+               region = nvm->regions[idx].id;
+               len = total_len;
+               if (len > nvm->regions[idx].size - from)
+                       len = nvm->regions[idx].size - from;
+
+               dev_dbg(&mtd->dev, "erasing region[%d] %s from %llx len %zx\n",
+                       region, nvm->regions[idx].name, from, len);
+
+               bytes = idg_erase(nvm, region, from, len, &info->fail_addr);
+               if (bytes < 0) {
+                       dev_dbg(&mtd->dev, "erase failed with %zd\n", bytes);
+                       info->fail_addr += nvm->regions[idx].offset;
+                       return bytes;
+               }
+
+               addr += len;
+               total_len -= len;
+       }
+
+       return 0;
+}
+
+static int intel_dg_mtd_read(struct mtd_info *mtd, loff_t from, size_t len,
+                            size_t *retlen, u_char *buf)
+{
+       struct intel_dg_nvm *nvm = mtd->priv;
+       ssize_t ret;
+       unsigned int idx;
+       u8 region;
+
+       if (WARN_ON(!nvm))
+               return -EINVAL;
+
+       idx = idg_nvm_get_region(nvm, from);
+
+       dev_dbg(&mtd->dev, "reading region[%d] %s from %lld len %zd\n",
+               nvm->regions[idx].id, nvm->regions[idx].name, from, len);
+
+       if (idx >= nvm->nregions) {
+               dev_err(&mtd->dev, "out of range");
+               return -ERANGE;
+       }
+
+       from -= nvm->regions[idx].offset;
+       region = nvm->regions[idx].id;
+       if (len > nvm->regions[idx].size - from)
+               len = nvm->regions[idx].size - from;
+
+       guard(mutex)(&nvm->lock);
+
+       ret = idg_read(nvm, region, from, len, buf);
+       if (ret < 0) {
+               dev_dbg(&mtd->dev, "read failed with %zd\n", ret);
+               return ret;
+       }
+
+       *retlen = ret;
+
+       return 0;
+}
+
+static int intel_dg_mtd_write(struct mtd_info *mtd, loff_t to, size_t len,
+                             size_t *retlen, const u_char *buf)
+{
+       struct intel_dg_nvm *nvm = mtd->priv;
+       ssize_t ret;
+       unsigned int idx;
+       u8 region;
+
+       if (WARN_ON(!nvm))
+               return -EINVAL;
+
+       idx = idg_nvm_get_region(nvm, to);
+
+       dev_dbg(&mtd->dev, "writing region[%d] %s to %lld len %zd\n",
+               nvm->regions[idx].id, nvm->regions[idx].name, to, len);
+
+       if (idx >= nvm->nregions) {
+               dev_err(&mtd->dev, "out of range");
+               return -ERANGE;
+       }
+
+       to -= nvm->regions[idx].offset;
+       region = nvm->regions[idx].id;
+       if (len > nvm->regions[idx].size - to)
+               len = nvm->regions[idx].size - to;
+
+       guard(mutex)(&nvm->lock);
+
+       ret = idg_write(nvm, region, to, len, buf);
+       if (ret < 0) {
+               dev_dbg(&mtd->dev, "write failed with %zd\n", ret);
+               return ret;
+       }
+
+       *retlen = ret;
+
+       return 0;
+}
+
 static void intel_dg_nvm_release(struct kref *kref)
 {
        struct intel_dg_nvm *nvm = container_of(kref, struct intel_dg_nvm, 
refcnt);
@@ -422,9 +564,80 @@ static void intel_dg_nvm_release(struct kref *kref)
        pr_debug("freeing intel_dg nvm\n");
        for (i = 0; i < nvm->nregions; i++)
                kfree(nvm->regions[i].name);
+       mutex_destroy(&nvm->lock);
        kfree(nvm);
 }
 
+static int intel_dg_mtd_get_device(struct mtd_info *mtd)
+{
+       struct mtd_info *master = mtd_get_master(mtd);
+       struct intel_dg_nvm *nvm = master->priv;
+
+       if (WARN_ON(!nvm))
+               return -EINVAL;
+       pr_debug("get mtd %s %d\n", mtd->name, kref_read(&nvm->refcnt));
+       kref_get(&nvm->refcnt);
+
+       return 0;
+}
+
+static void intel_dg_mtd_put_device(struct mtd_info *mtd)
+{
+       struct mtd_info *master = mtd_get_master(mtd);
+       struct intel_dg_nvm *nvm = master->priv;
+
+       if (WARN_ON(!nvm))
+               return;
+       pr_debug("put mtd %s %d\n", mtd->name, kref_read(&nvm->refcnt));
+       kref_put(&nvm->refcnt, intel_dg_nvm_release);
+}
+
+static int intel_dg_nvm_init_mtd(struct intel_dg_nvm *nvm, struct device 
*device,
+                                unsigned int nparts, bool writable_override)
+{
+       unsigned int i;
+       unsigned int n;
+       struct mtd_partition *parts = NULL;
+       int ret;
+
+       dev_dbg(device, "registering with mtd\n");
+
+       nvm->mtd.owner = THIS_MODULE;
+       nvm->mtd.dev.parent = device;
+       nvm->mtd.flags = MTD_CAP_NORFLASH | MTD_WRITEABLE;
+       nvm->mtd.type = MTD_DATAFLASH;
+       nvm->mtd.priv = nvm;
+       nvm->mtd._write = intel_dg_mtd_write;
+       nvm->mtd._read = intel_dg_mtd_read;
+       nvm->mtd._erase = intel_dg_mtd_erase;
+       nvm->mtd._get_device = intel_dg_mtd_get_device;
+       nvm->mtd._put_device = intel_dg_mtd_put_device;
+       nvm->mtd.writesize = SZ_1; /* 1 byte granularity */
+       nvm->mtd.erasesize = SZ_4K; /* 4K bytes granularity */
+       nvm->mtd.size = nvm->size;
+
+       parts = kcalloc(nvm->nregions, sizeof(*parts), GFP_KERNEL);
+       if (!parts)
+               return -ENOMEM;
+
+       for (i = 0, n = 0; i < nvm->nregions && n < nparts; i++) {
+               if (!nvm->regions[i].is_readable)
+                       continue;
+               parts[n].name = nvm->regions[i].name;
+               parts[n].offset  = nvm->regions[i].offset;
+               parts[n].size = nvm->regions[i].size;
+               if (!nvm->regions[i].is_writable && !writable_override)
+                       parts[n].mask_flags = MTD_WRITEABLE;
+               n++;
+       }
+
+       ret = mtd_device_register(&nvm->mtd, parts, n);
+
+       kfree(parts);
+
+       return ret;
+}
+
 static int intel_dg_mtd_probe(struct auxiliary_device *aux_dev,
                              const struct auxiliary_device_id *aux_dev_id)
 {
@@ -454,6 +667,7 @@ static int intel_dg_mtd_probe(struct auxiliary_device 
*aux_dev,
                return -ENOMEM;
 
        kref_init(&nvm->refcnt);
+       mutex_init(&nvm->lock);
 
        nvm->nregions = nregions;
        for (n = 0, i = 0; i < INTEL_DG_NVM_REGIONS; i++) {
@@ -483,6 +697,12 @@ static int intel_dg_mtd_probe(struct auxiliary_device 
*aux_dev,
                goto err;
        }
 
+       ret = intel_dg_nvm_init_mtd(nvm, device, ret, invm->writable_override);
+       if (ret) {
+               dev_err(device, "failed init mtd %d\n", ret);
+               goto err;
+       }
+
        dev_set_drvdata(&aux_dev->dev, nvm);
 
        return 0;
@@ -499,6 +719,8 @@ static void intel_dg_mtd_remove(struct auxiliary_device 
*aux_dev)
        if (!nvm)
                return;
 
+       mtd_device_unregister(&nvm->mtd);
+
        dev_set_drvdata(&aux_dev->dev, NULL);
 
        kref_put(&nvm->refcnt, intel_dg_nvm_release);
-- 
2.43.0

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