dm: core: Add a command to show driver model statistics

This command shows the memory used by driver model along with various
hints as to what it might be if some 'core' tags were moved to use the
tag list instead of a core (i.e. always-there) pointer.

This may help with future work to reduce memory usage.

Signed-off-by: Simon Glass <sjg@chromium.org>

drivers/core/Kconfig

@@ -75,6 +75,17 @@ config DM_DEBUG
 	help
 	  Say Y here if you want to compile in debug messages in DM core.
 
+config DM_STATS
+	bool "Collect and show driver model stats"
+	depends on DM
+	default y if SANDBOX
+	help
+	  Enable this to collect and display memory statistics about driver
+	  model. This can help to figure out where all the memory is going and
+	  to find optimisations.
+
+	  To display the memory stats, use the 'dm mem' command.
+
 config DM_DEVICE_REMOVE
 	bool "Support device removal"
 	depends on DM

drivers/core/dump.c

@@ -172,3 +172,76 @@ void dm_dump_static_driver_info(void)
 	for (entry = drv; entry != drv + n_ents; entry++)
 		printf("%-25.25s %p\n", entry->name, entry->plat);
 }
+
+void dm_dump_mem(struct dm_stats *stats)
+{
+	int total, total_delta;
+	int i;
+
+	/* Support SPL printf() */
+	printf("Struct sizes: udevice %x, driver %x, uclass %x, uc_driver %x\n",
+	       (int)sizeof(struct udevice), (int)sizeof(struct driver),
+	       (int)sizeof(struct uclass), (int)sizeof(struct uclass_driver));
+	printf("Memory: device %x:%x, device names %x, uclass %x:%x\n",
+	       stats->dev_count, stats->dev_size, stats->dev_name_size,
+	       stats->uc_count, stats->uc_size);
+	printf("\n");
+	printf("%-15s  %5s  %5s  %5s  %5s  %5s\n", "Attached type", "Count",
+	       "Size", "Cur", "Tags", "Save");
+	printf("%-15s  %5s  %5s  %5s  %5s  %5s\n", "---------------", "-----",
+	       "-----", "-----", "-----", "-----");
+	total_delta = 0;
+	for (i = 0; i < DM_TAG_ATTACH_COUNT; i++) {
+		int cur_size, new_size, delta;
+
+		cur_size = stats->dev_count * sizeof(struct udevice);
+		new_size = stats->dev_count * (sizeof(struct udevice) -
+			sizeof(void *));
+		/*
+		 * Let's assume we can fit each dmtag_node into 32 bits. We can
+		 * limit the 'tiny tags' feature to SPL with
+		 * CONFIG_SPL_SYS_MALLOC_F_LEN <= 64KB, so needing 14 bits to
+		 * point to anything in that region (with 4-byte alignment).
+		 * So:
+		 *    4 bits for tag
+		 *    14 bits for offset of dev
+		 *    14 bits for offset of data
+		 */
+		new_size += stats->attach_count[i] * sizeof(u32);
+		delta = cur_size - new_size;
+		total_delta += delta;
+		printf("%-16s %5x %6x %6x %6x %6x (%d)\n", tag_get_name(i),
+		       stats->attach_count[i], stats->attach_size[i],
+		       cur_size, new_size, delta > 0 ? delta : 0, delta);
+	}
+	printf("%-16s %5x %6x\n", "uclass", stats->uc_attach_count,
+	       stats->uc_attach_size);
+	printf("%-16s %5x %6x  %5s  %5s  %6x (%d)\n", "Attached total",
+	       stats->attach_count_total + stats->uc_attach_count,
+	       stats->attach_size_total + stats->uc_attach_size, "", "",
+	       total_delta > 0 ? total_delta : 0, total_delta);
+	printf("%-16s %5x %6x\n", "tags", stats->tag_count, stats->tag_size);
+	printf("\n");
+	printf("Total size: %x (%d)\n", stats->total_size, stats->total_size);
+	printf("\n");
+
+	total = stats->total_size;
+	total -= total_delta;
+	printf("With tags:       %x (%d)\n", total, total);
+
+	/* Use singly linked lists in struct udevice (3 nodes in each) */
+	total -= sizeof(void *) * 3 * stats->dev_count;
+	printf("- singly-linked: %x (%d)\n", total, total);
+
+	/* Use an index into the struct_driver list instead of a pointer */
+	total = total + stats->dev_count * (1 - sizeof(void *));
+	printf("- driver index:  %x (%d)\n", total, total);
+
+	/* Same with the uclass */
+	total = total + stats->dev_count * (1 - sizeof(void *));
+	printf("- uclass index:  %x (%d)\n", total, total);
+
+	/* Drop the device name */
+	printf("Drop device name (not SRAM): %x (%d)\n", stats->dev_name_size,
+	       stats->dev_name_size);
+}

drivers/core/tag.c

@@ -16,6 +16,24 @@ struct udevice;
 
 DECLARE_GLOBAL_DATA_PTR;
 
+static const char *const tag_name[] = {
+	[DM_TAG_PLAT]		= "plat",
+	[DM_TAG_PARENT_PLAT]	= "parent_plat",
+	[DM_TAG_UC_PLAT]	= "uclass_plat",
+
+	[DM_TAG_PRIV]		= "priv",
+	[DM_TAG_PARENT_PRIV]	= "parent_priv",
+	[DM_TAG_UC_PRIV]	= "uclass_priv",
+	[DM_TAG_DRIVER_DATA]	= "driver_data",
+
+	[DM_TAG_EFI]		= "efi",
+};
+
+const char *tag_get_name(enum dm_tag_t tag)
+{
+	return tag_name[tag];
+}
+
 int dev_tag_set_ptr(struct udevice *dev, enum dm_tag_t tag, void *ptr)
 {
 	struct dmtag_node *node;