Re: [PATCH v5 02/11] drivers: of: add initialization code for static reserved memory
On Fri, 21 Feb 2014 13:25:18 +0100, Marek Szyprowski
wrote:
> This patch adds support for static (defined by 'reg' property) reserved
> memory regions declared in device tree.
>
> Memory blocks can be reliably reserved only during early boot. This must
> happen before the whole memory management subsystem is initialized,
> because we need to ensure that the given contiguous blocks are not yet
> allocated by kernel. Also it must happen before kernel mappings for the
> whole low memory are created, to ensure that there will be no mappings
> (for reserved blocks). Typically, all this happens before device tree
> structures are unflattened, so we need to get reserved memory layout
> directly from fdt.
>
> Based on previous code provided by Josh Cartwright
>
> Signed-off-by: Marek Szyprowski
> ---
> drivers/of/fdt.c | 125
>
> include/linux/of_fdt.h |3 ++
> 2 files changed, 128 insertions(+)
>
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index 758b4f8b30b7..12809e20ef71 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -440,6 +440,113 @@ struct boot_param_header *initial_boot_params;
> #ifdef CONFIG_OF_EARLY_FLATTREE
>
> /**
> + * res_mem_reserve_reg() - reserve all memory described in 'reg' property
> + */
> +static int __init __reserved_mem_reserve_reg(unsigned long node,
> + const char *uname)
> +{
> + int t_len = (dt_root_addr_cells + dt_root_size_cells) * sizeof(__be32);
> + phys_addr_t base, size;
> + unsigned long len;
> + __be32 *prop;
> + int nomap;
> +
> + prop = of_get_flat_dt_prop(node, "reg", &len);
> + if (!prop)
> + return -ENOENT;
> +
> + if (len && len % t_len != 0) {
> + pr_err("Reserved memory: invalid reg property in '%s', skipping
> node.\n",
> +uname);
> + return -EINVAL;
> + }
> +
> + nomap = of_get_flat_dt_prop(node, "no-map", NULL) != NULL;
> +
> + while (len > 0) {
This is safer: while (len >= t_len) {
> + base = dt_mem_next_cell(dt_root_addr_cells, &prop);
> + size = dt_mem_next_cell(dt_root_size_cells, &prop);
> +
> + if (base && size &&
> + early_init_dt_reserve_memory_arch(base, size, nomap) == 0)
> + pr_debug("Reserved memory: reserved region for node
> '%s': base %pa, size %ld MiB\n",
> + uname, &base, (unsigned long)size / SZ_1M);
> + else
> + pr_info("Reserved memory: failed to reserve memory for
> node '%s': base %pa, size %ld MiB\n",
> + uname, &base, (unsigned long)size / SZ_1M);
> +
> + len -= t_len;
> + }
> + return 0;
> +}
> +
> +static int __reserved_mem_check_root(unsigned long node)
Please document the purpose of this function. This function reflects a Linux
implementation limitation because it is easier than parsing a correctly
formed ranges property. Sometime in the future it may be fixed. It is
worth capturing all of that in a comment.
> +{
> + __be32 *prop;
> +
> + prop = of_get_flat_dt_prop(node, "#size-cells", NULL);
> + if (prop && be32_to_cpup(prop) != dt_root_size_cells)
> + return -EINVAL;
> +
> + prop = of_get_flat_dt_prop(node, "#address-cells", NULL);
> + if (prop && be32_to_cpup(prop) != dt_root_addr_cells)
> + return -EINVAL;
> +
> + prop = of_get_flat_dt_prop(node, "ranges", NULL);
> + if (!prop)
> + return -EINVAL;
> + return 0;
> +}
> +
> +/**
> + * fdt_scan_reserved_mem() - scan a single FDT node for reserved memory
> + */
> +static int __init __fdt_scan_reserved_mem(unsigned long node, const char
> *uname,
> + int depth, void *data)
> +{
> + static int found;
> + const char *status;
> +
> + if (!found && depth == 1 && strcmp(uname, "reserved-memory") == 0) {
> + if (__reserved_mem_check_root(node) != 0) {
> + pr_err("Reserved memory: unsupported node format,
> ignoring\n");
> + /* break scan */
> + return 1;
> + }
> + found = 1;
> + /* scan next node */
> + return 0;
> + } else if (!found) {
> + /* scan next node */
> + return 0;
> + } else if (found && depth < 2) {
> + /* scanning of /reserved-memory has been finished */
> + return 1;
> + }
> +
> + status = of_get_flat_dt_prop(node, "status", NULL);
> + if (status && strcmp(status, "okay") != 0 && strcmp(status, "ok") != 0)
> + return 0;
> +
> + __reserved_mem_reserve_reg(node, uname);
> +
> + /* scan next node */
> + return 0;
> +}
> +
> +/**
> + * early_init_fdt_scan_reserved_mem() - create reserved memory regions
> + *
> + * This function grabs memory fro
[PATCH v5 02/11] drivers: of: add initialization code for static reserved memory
This patch adds support for static (defined by 'reg' property) reserved
memory regions declared in device tree.
Memory blocks can be reliably reserved only during early boot. This must
happen before the whole memory management subsystem is initialized,
because we need to ensure that the given contiguous blocks are not yet
allocated by kernel. Also it must happen before kernel mappings for the
whole low memory are created, to ensure that there will be no mappings
(for reserved blocks). Typically, all this happens before device tree
structures are unflattened, so we need to get reserved memory layout
directly from fdt.
Based on previous code provided by Josh Cartwright
Signed-off-by: Marek Szyprowski
---
drivers/of/fdt.c | 125
include/linux/of_fdt.h |3 ++
2 files changed, 128 insertions(+)
diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index 758b4f8b30b7..12809e20ef71 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -440,6 +440,113 @@ struct boot_param_header *initial_boot_params;
#ifdef CONFIG_OF_EARLY_FLATTREE
/**
+ * res_mem_reserve_reg() - reserve all memory described in 'reg' property
+ */
+static int __init __reserved_mem_reserve_reg(unsigned long node,
+const char *uname)
+{
+ int t_len = (dt_root_addr_cells + dt_root_size_cells) * sizeof(__be32);
+ phys_addr_t base, size;
+ unsigned long len;
+ __be32 *prop;
+ int nomap;
+
+ prop = of_get_flat_dt_prop(node, "reg", &len);
+ if (!prop)
+ return -ENOENT;
+
+ if (len && len % t_len != 0) {
+ pr_err("Reserved memory: invalid reg property in '%s', skipping
node.\n",
+ uname);
+ return -EINVAL;
+ }
+
+ nomap = of_get_flat_dt_prop(node, "no-map", NULL) != NULL;
+
+ while (len > 0) {
+ base = dt_mem_next_cell(dt_root_addr_cells, &prop);
+ size = dt_mem_next_cell(dt_root_size_cells, &prop);
+
+ if (base && size &&
+ early_init_dt_reserve_memory_arch(base, size, nomap) == 0)
+ pr_debug("Reserved memory: reserved region for node
'%s': base %pa, size %ld MiB\n",
+ uname, &base, (unsigned long)size / SZ_1M);
+ else
+ pr_info("Reserved memory: failed to reserve memory for
node '%s': base %pa, size %ld MiB\n",
+ uname, &base, (unsigned long)size / SZ_1M);
+
+ len -= t_len;
+ }
+ return 0;
+}
+
+static int __reserved_mem_check_root(unsigned long node)
+{
+ __be32 *prop;
+
+ prop = of_get_flat_dt_prop(node, "#size-cells", NULL);
+ if (prop && be32_to_cpup(prop) != dt_root_size_cells)
+ return -EINVAL;
+
+ prop = of_get_flat_dt_prop(node, "#address-cells", NULL);
+ if (prop && be32_to_cpup(prop) != dt_root_addr_cells)
+ return -EINVAL;
+
+ prop = of_get_flat_dt_prop(node, "ranges", NULL);
+ if (!prop)
+ return -EINVAL;
+ return 0;
+}
+
+/**
+ * fdt_scan_reserved_mem() - scan a single FDT node for reserved memory
+ */
+static int __init __fdt_scan_reserved_mem(unsigned long node, const char
*uname,
+ int depth, void *data)
+{
+ static int found;
+ const char *status;
+
+ if (!found && depth == 1 && strcmp(uname, "reserved-memory") == 0) {
+ if (__reserved_mem_check_root(node) != 0) {
+ pr_err("Reserved memory: unsupported node format,
ignoring\n");
+ /* break scan */
+ return 1;
+ }
+ found = 1;
+ /* scan next node */
+ return 0;
+ } else if (!found) {
+ /* scan next node */
+ return 0;
+ } else if (found && depth < 2) {
+ /* scanning of /reserved-memory has been finished */
+ return 1;
+ }
+
+ status = of_get_flat_dt_prop(node, "status", NULL);
+ if (status && strcmp(status, "okay") != 0 && strcmp(status, "ok") != 0)
+ return 0;
+
+ __reserved_mem_reserve_reg(node, uname);
+
+ /* scan next node */
+ return 0;
+}
+
+/**
+ * early_init_fdt_scan_reserved_mem() - create reserved memory regions
+ *
+ * This function grabs memory from early allocator for device exclusive use
+ * defined in device tree structures. It should be called by arch specific code
+ * once the early allocator (i.e. memblock) has been fully activated.
+ */
+void __init early_init_fdt_scan_reserved_mem(void)
+{
+ of_scan_flat_dt(__fdt_scan_reserved_mem, NULL);
+}
+
+/**
* of_scan_flat_dt - scan flattened tree blob and call callback on each.
* @it: callback function
* @data: context data pointer
@@ -856,6 +963,16 @@ void __init __weak early_in
