Add nvmem-sg driver which adds provisions to create fake 'nvmem' devices
whose cells are comprised of bits and pieces of other 'nvmem' cells in
a scatter-gather manner.
Signed-off-by: Andrey Smirnov <andrew.smirnov@xxxxxxxxx>
---
drivers/misc/Makefile | 1 +
drivers/misc/nvmem-sg.c | 287 ++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 288 insertions(+)
create mode 100644 drivers/misc/nvmem-sg.c
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index c7f56f8..d048596 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -7,3 +7,4 @@ obj-$(CONFIG_SRAM) += sram.o
obj-$(CONFIG_STATE_DRV) += state.o
obj-y += mac-address-map.o
obj-y += nvmem-ro-of-blob.o
+obj-y += nvmem-sg.o
diff --git a/drivers/misc/nvmem-sg.c b/drivers/misc/nvmem-sg.c
new file mode 100644
index 0000000..7fd5eb4
--- /dev/null
+++ b/drivers/misc/nvmem-sg.c
@@ -0,0 +1,287 @@
+#include <common.h>
+#include <driver.h>
+#include <init.h>
+#include <malloc.h>
+#include <of.h>
+#include <state.h>
+#include <io.h>
+#include <fcntl.h>
+#include <net.h>
+#include <regmap.h>
+
+#include <linux/err.h>
+#include <linux/nvmem-provider.h>
+#include <linux/nvmem-consumer.h>
+
+struct nvmem_sg {
+ struct regmap *map;
+ struct nvmem_config config;
+ struct nvmem_device *nvmem;
+
+ struct list_head cells;
+};
+
+struct nvmem_sg_item {
+ struct nvmem_cell *cell;
+
+ size_t idx;
+ size_t start;
+ size_t end;
+ size_t size;
+
+ struct list_head node;
+};
+
+struct nvmem_sg_cell {
+ struct nvmem_sg *nsg;
+
+ size_t start;
+ size_t end;
+ size_t size;
+
+ struct list_head layout;
+ struct list_head node;
+};
+
+struct nvmem_sg_item *nvmem_sg_find_item(struct nvmem_sg_cell *cell,
+ unsigned int nr)
+{
+ struct nvmem_sg_item *item;
+ list_for_each_entry(item, &cell->layout, node) {
+ pr_info("[%d %d]\n", item->start, item->end);
+ if (item->start <= nr && nr <= item->end)
+ return item;
+ }
+
+ return NULL;
+}
+
+
+static int nvmem_sg_cell_read_byte(struct nvmem_sg_cell *cell,
+ unsigned int nr,
+ unsigned int *val)
+{
+ unsigned int size;
+ uint8_t *data;
+ struct nvmem_sg_item *item = nvmem_sg_find_item(cell, nr);
+
+ if (!item)
+ return -EINVAL;
+
+ data = nvmem_cell_read(item->cell, &size);
+ if (IS_ERR(data)) {
+ dev_dbg(cell->nsg->config.dev,
+ "Failed to read a cell\n");
+ return PTR_ERR(data);
+ }
+
+ *val = data[nr - item->start + item->idx];
+ pr_info("nr: %d %x\n", nr, *val);
+
+ free(data);
+ return 0;
+}
+
+struct nvmem_sg_cell *nvmem_sg_find_cell(struct nvmem_sg *nsg,
+ unsigned int reg)
+{
+ struct nvmem_sg_cell *cell;
+
+ list_for_each_entry(cell, &nsg->cells, node)
+ if (cell->start <= reg && reg <= cell->end)
+ return cell;
+
+ return NULL;
+}
+
+static int nvmem_sg_reg_write(void *ctx, unsigned int reg,
+ unsigned int val)
+{
+ return -ENOTSUPP;
+}
+
+static int nvmem_sg_reg_read(void *ctx, unsigned int reg,
+ unsigned int *val)
+{
+ struct nvmem_sg *nsg = ctx;
+ struct nvmem_sg_cell *cell = nvmem_sg_find_cell(nsg, reg);
+
+ if (cell) {
+ const unsigned int nr = reg - cell->start;
+ return nvmem_sg_cell_read_byte(cell, nr, val);
+ }
+
+ pr_debug("No sg cell found for reg %x\n", reg);
+ return -ENOENT;
+}
+
+static const struct regmap_bus nvmem_sg_regmap_bus = {
+ .reg_write = nvmem_sg_reg_write,
+ .reg_read = nvmem_sg_reg_read,
+};
+
+static const struct regmap_config nvmem_sg_regmap_config = {
+ .reg_bits = 8,
+ .val_bits = 8,
+ .reg_stride = 1,
+ .max_register = 0xbc,
+};
+
+static int nvmem_sg_validate_dt(struct device_node *np)
+{
+ /* FIXME */
+ return 0;
+}
+
+static int nvmem_sg_cell_populate(struct nvmem_sg_cell *sg_cell,
+ struct device_node *sg_cell_np)
+{
+ int i;
+ int ret;
+ int len;
+ size_t start;
+
+ struct nvmem_sg_item *item = NULL;
+ const __be32 *addr = of_get_property(sg_cell_np, "layout", &len);
+ const unsigned int cell_count = len / (3 * sizeof(__be32));
+
+ BUG_ON(!addr);
+ BUG_ON(!cell_count);
+
+ start = 0;
+ for (i = 0; i < cell_count; i++) {
+ struct device_node *cell_np;
+ uint32_t phandle;
+
+ item = xzalloc(sizeof(*item));
+
+ phandle = be32_to_cpup(addr++);
+ cell_np = of_find_node_by_phandle(phandle);
+ if (!cell_np) {
+ dev_dbg(sg_cell->nsg->config.dev,
+ "No device tree node corresponds to phandle\n");
+ ret = -ENOENT;
+ goto unwind;
+ }
+
+ item->cell = of_nvmem_cell_from_cell_np(cell_np);
+ if (IS_ERR(item->cell)) {
+ dev_dbg(sg_cell->nsg->config.dev,
+ "Failed to instantiate nvmem cell from "
+ "a device tree node\n");
+ ret = PTR_ERR(item->cell);
+ goto unwind;
+ }
+
+ item->start = start;
+ item->idx = be32_to_cpup(addr++);
+ item->size = be32_to_cpup(addr++);
+ item->end = item->start + item->size - 1;
+ start += item->size;
+
+ list_add_tail(&item->node, &sg_cell->layout);
+ }
+
+ return 0;
+
+unwind:
+ free(item);
+ /* FIXME */
+ BUG();
+
+ return ret;
+}
+
+static int nvmem_sg_probe(struct device_d *dev)
+{
+ int ret;
+ struct device_node *np = dev->device_node;
+ struct device_node *child;
+
+ struct nvmem_sg *nsg;
+ struct nvmem_sg_cell *cell;
+
+ BUG_ON(!np);
+
+ if (!of_get_next_child(np, NULL)) {
+ dev_dbg(dev, "Device node doesn't specify any cells\n");
+ return -EINVAL;
+ }
+
+ ret = nvmem_sg_validate_dt(np);
+ if (ret < 0) {
+ dev_dbg(dev, "Device validation failed\n");
+ return ret;
+ }
+
+ nsg = xzalloc(sizeof(*nsg));
+ INIT_LIST_HEAD(&nsg->cells);
+
+ for_each_child_of_node(np, child) {
+ const __be32 *addr;
+ int len;
+
+ addr = of_get_property(child, "reg", &len);
+ BUG_ON(!addr);
+
+ cell = xzalloc(sizeof(*cell));
+ INIT_LIST_HEAD(&cell->layout);
+ cell->nsg = nsg;
+ cell->start = be32_to_cpup(addr++);
+ cell->size = be32_to_cpup(addr);
+ cell->end = cell->start + cell->size - 1;
+
+ ret = nvmem_sg_cell_populate(cell, child);
+ if (ret < 0) {
+ dev_dbg(dev,
+ "Failed to popluate sg-cell\n");
+ goto free_resources;
+ }
+
+ list_add_tail(&cell->node, &nsg->cells);
+ }
+
+ nsg->map = regmap_init(dev,
+ &nvmem_sg_regmap_bus,
+ nsg,
+ &nvmem_sg_regmap_config);
+ if (IS_ERR(nsg->map)) {
+ dev_dbg(dev, "Failed to register 'nvmem' device\n");
+ ret = PTR_ERR(nsg->map);
+ goto free_resources;
+ }
+
+ nsg->config.name = "nvmem-sg";
+ nsg->config.read_only = true;
+ nsg->config.dev = dev;
+
+ nsg->nvmem = nvmem_register(&nsg->config, nsg->map);
+ if (IS_ERR(nsg->nvmem)) {
+ dev_dbg(dev, "Failed to register 'nvmem' device\n");
+ ret = PTR_ERR(nsg->nvmem);
+ goto free_resources;
+ }
+
+ dev_dbg(dev, "probed\n");
+ return 0;
+
+free_resources:
+ /* FIXME */
+ BUG();
+ return ret;
+}
+
+static __maybe_unused struct of_device_id nvmem_sg_ids[] = {
+ {
+ .compatible = "barebox,nvmem-sg",
+ }, {
+ /* sentinel */
+ }
+};
+
+static struct driver_d nvmem_sg_driver = {
+ .name = "nvmem-sg",
+ .probe = nvmem_sg_probe,
+ .of_compatible = DRV_OF_COMPAT(nvmem_sg_ids),
+};
+device_platform_driver(nvmem_sg_driver);
--
2.5.0
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