---
Changes in v3:
- Use min()/max() macros instead of defining my own (Doug)
- Comment changes to indicate sorting (Doug)
- Add function to validate keepouts are proper (Doug)
Changes in v2:
- Introduced keepout regions into the core (Srini)
drivers/nvmem/core.c | 153 ++++++++++++++++++++++++++++++++-
include/linux/nvmem-provider.h | 17 ++++
2 files changed, 166 insertions(+), 4 deletions(-)
diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index a09ff8409f600..177f5bf27c6d5 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);
diff --git a/include/linux/nvmem-provider.h b/include/linux/nvmem-provider.h
index 06409a6c40bcb..e162b757b6d54 100644
--- a/include/linux/nvmem-provider.h
+++ b/include/linux/nvmem-provider.h
@@ -30,6 +30,19 @@ enum nvmem_type {
#define NVMEM_DEVID_NONE (-1)
#define NVMEM_DEVID_AUTO (-2)
+/**
+ * struct nvmem_keepout - NVMEM register keepout range.
+ *
+ * @start: The first byte offset to avoid.
+ * @end: One beyond the last byte offset to avoid.
+ * @value: The byte to fill reads with for this region.
+ */
+struct nvmem_keepout {
+ unsigned int start;
+ unsigned int end;
+ unsigned char value;
+};
+
/**
* struct nvmem_config - NVMEM device configuration
*
@@ -39,6 +52,8 @@ enum nvmem_type {
* @owner: Pointer to exporter module. Used for refcounting.
* @cells: Optional array of pre-defined NVMEM cells.
* @ncells: Number of elements in cells.
+ * @keepout: Optional array of keepout ranges (sorted ascending by start).
+ * @nkeepout: Number of elements in the keepout array.
* @type: Type of the nvmem storage
* @read_only: Device is read-only.
* @root_only: Device is accessibly to root only.
@@ -66,6 +81,8 @@ struct nvmem_config {
struct gpio_desc *wp_gpio;
const struct nvmem_cell_info *cells;
int ncells;
+ const struct nvmem_keepout *keepout;
+ unsigned int nkeepout;
enum nvmem_type type;
bool read_only;
bool root_only;
