1 files changed, 149 insertions, 4 deletions

diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index a09ff8409f60..177f5bf27c6d 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -34,6 +34,8 @@ struct nvmem_device {
 	struct bin_attribute	eeprom;
 	struct device		*base_dev;
 	struct list_head	cells;
+	const struct nvmem_keepout *keepout;
+	unsigned int		nkeepout;
 	nvmem_reg_read_t	reg_read;
 	nvmem_reg_write_t	reg_write;
 	struct gpio_desc	*wp_gpio;
@@ -66,8 +68,8 @@ static LIST_HEAD(nvmem_lookup_list);
 
 static BLOCKING_NOTIFIER_HEAD(nvmem_notifier);
 
-static int nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset,
-			  void *val, size_t bytes)
+static int __nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset,
+			    void *val, size_t bytes)
 {
 	if (nvmem->reg_read)
 		return nvmem->reg_read(nvmem->priv, offset, val, bytes);
@@ -75,8 +77,8 @@ static int nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset,
 	return -EINVAL;
 }
 
-static int nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset,
-			   void *val, size_t bytes)
+static int __nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset,
+			     void *val, size_t bytes)
 {
 	int ret;
 
@@ -90,6 +92,88 @@ static int nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset,
 	return -EINVAL;
 }
 
+static int nvmem_access_with_keepouts(struct nvmem_device *nvmem,
+				      unsigned int offset, void *val,
+				      size_t bytes, int write)
+{
+
+	unsigned int end = offset + bytes;
+	unsigned int kend, ksize;
+	const struct nvmem_keepout *keepout = nvmem->keepout;
+	const struct nvmem_keepout *keepoutend = keepout + nvmem->nkeepout;
+	int rc;
+
+	/*
+	 * Skip all keepouts before the range being accessed.
+	 * Keepouts are sorted.
+	 */
+	while ((keepout < keepoutend) && (keepout->end <= offset))
+		keepout++;
+
+	while ((offset < end) && (keepout < keepoutend)) {
+		/* Access the valid portion before the keepout. */
+		if (offset < keepout->start) {
+			kend = min(end, keepout->start);
+			ksize = kend - offset;
+			if (write)
+				rc = __nvmem_reg_write(nvmem, offset, val, ksize);
+			else
+				rc = __nvmem_reg_read(nvmem, offset, val, ksize);
+
+			if (rc)
+				return rc;
+
+			offset += ksize;
+			val += ksize;
+		}
+
+		/*
+		 * Now we're aligned to the start of this keepout zone. Go
+		 * through it.
+		 */
+		kend = min(end, keepout->end);
+		ksize = kend - offset;
+		if (!write)
+			memset(val, keepout->value, ksize);
+
+		val += ksize;
+		offset += ksize;
+		keepout++;
+	}
+
+	/*
+	 * If we ran out of keepouts but there's still stuff to do, send it
+	 * down directly
+	 */
+	if (offset < end) {
+		ksize = end - offset;
+		if (write)
+			return __nvmem_reg_write(nvmem, offset, val, ksize);
+		else
+			return __nvmem_reg_read(nvmem, offset, val, ksize);
+	}
+
+	return 0;
+}
+
+static int nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset,
+			  void *val, size_t bytes)
+{
+	if (!nvmem->nkeepout)
+		return __nvmem_reg_read(nvmem, offset, val, bytes);
+
+	return nvmem_access_with_keepouts(nvmem, offset, val, bytes, false);
+}
+
+static int nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset,
+			   void *val, size_t bytes)
+{
+	if (!nvmem->nkeepout)
+		return __nvmem_reg_write(nvmem, offset, val, bytes);
+
+	return nvmem_access_with_keepouts(nvmem, offset, val, bytes, true);
+}
+
 #ifdef CONFIG_NVMEM_SYSFS
 static const char * const nvmem_type_str[] = {
 	[NVMEM_TYPE_UNKNOWN] = "Unknown",
@@ -533,6 +617,59 @@ nvmem_find_cell_by_name(struct nvmem_device *nvmem, const char *cell_id)
 	return cell;
 }
 
+static int nvmem_validate_keepouts(struct nvmem_device *nvmem)
+{
+	unsigned int cur = 0;
+	const struct nvmem_keepout *keepout = nvmem->keepout;
+	const struct nvmem_keepout *keepoutend = keepout + nvmem->nkeepout;
+
+	while (keepout < keepoutend) {
+		/* Ensure keepouts are sorted and don't overlap. */
+		if (keepout->start < cur) {
+			dev_err(&nvmem->dev,
+				"Keepout regions aren't sorted or overlap.\n");
+
+			return -ERANGE;
+		}
+
+		if (keepout->end < keepout->start) {
+			dev_err(&nvmem->dev,
+				"Invalid keepout region.\n");
+
+			return -EINVAL;
+		}
+
+		/*
+		 * Validate keepouts (and holes between) don't violate
+		 * word_size constraints.
+		 */
+		if ((keepout->end - keepout->start < nvmem->word_size) ||
+		    ((keepout->start != cur) &&
+		     (keepout->start - cur < nvmem->word_size))) {
+
+			dev_err(&nvmem->dev,
+				"Keepout regions violate word_size constraints.\n");
+
+			return -ERANGE;
+		}
+
+		/* Validate keepouts don't violate stride (alignment). */
+		if (!IS_ALIGNED(keepout->start, nvmem->stride) ||
+		    !IS_ALIGNED(keepout->end, nvmem->stride)) {
+
+			dev_err(&nvmem->dev,
+				"Keepout regions violate stride.\n");
+
+			return -EINVAL;
+		}
+
+		cur = keepout->end;
+		keepout++;
+	}
+
+	return 0;
+}
+
 static int nvmem_add_cells_from_of(struct nvmem_device *nvmem)
 {
 	struct device_node *parent, *child;
@@ -647,6 +784,8 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
 	nvmem->type = config->type;
 	nvmem->reg_read = config->reg_read;
 	nvmem->reg_write = config->reg_write;
+	nvmem->keepout = config->keepout;
+	nvmem->nkeepout = config->nkeepout;
 	if (!config->no_of_node)
 		nvmem->dev.of_node = config->dev->of_node;
 
@@ -671,6 +810,12 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
 	nvmem->dev.groups = nvmem_dev_groups;
 #endif
 
+	if (nvmem->nkeepout) {
+		rval = nvmem_validate_keepouts(nvmem);
+		if (rval)
+			goto err_put_device;
+	}
+
 	dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name);
 
 	rval = device_register(&nvmem->dev);