soc: qcom: cmd-db: Add debugfs dumping file

It's useful for kernel devs to understand what resources and data is
stored inside command db. Add a file in debugufs called 'cmd-db' to dump
the memory contents and strings for resources along with their
addresses. E.g.

 Command DB DUMP
 Slave ARC (v16.0)
 -------------------------
 0x00030000: cx.lvl [00 00 10 00 40 00 80 00 c0 00 00 01 80 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00]
 0x00030004: cx.tmr
 0x00030010: mx.lvl [00 00 10 00 00 01 80 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00]
 0x00030014: mx.tmr

Cc: Lina Iyer <ilina@codeaurora.org>
Cc: Maulik Shah <mkshah@codeaurora.org>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/20200309185704.2491-1-swboyd@chromium.orgSigned-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

drivers/soc/qcom/cmd-db.c

 /* SPDX-License-Identifier: GPL-2.0 */
 /* Copyright (c) 2016-2018, The Linux Foundation. All rights reserved. */
 
+#include <linux/debugfs.h>
 #include <linux/kernel.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
-#include <linux/of_platform.h>
 #include <linux/of_reserved_mem.h>
 #include <linux/platform_device.h>
+#include <linux/seq_file.h>
 #include <linux/types.h>
 
 #include <soc/qcom/cmd-db.h>
@@ -236,6 +237,77 @@ enum cmd_db_hw_type cmd_db_read_slave_id(const char *id)
 }
 EXPORT_SYMBOL(cmd_db_read_slave_id);
 
+#ifdef CONFIG_DEBUG_FS
+static int cmd_db_debugfs_dump(struct seq_file *seq, void *p)
+{
+	int i, j;
+	const struct rsc_hdr *rsc;
+	const struct entry_header *ent;
+	const char *name;
+	u16 len, version;
+	u8 major, minor;
+
+	seq_puts(seq, "Command DB DUMP\n");
+
+	for (i = 0; i < MAX_SLV_ID; i++) {
+		rsc = &cmd_db_header->header[i];
+		if (!rsc->slv_id)
+			break;
+
+		switch (rsc->slv_id) {
+		case CMD_DB_HW_ARC:
+			name = "ARC";
+			break;
+		case CMD_DB_HW_VRM:
+			name = "VRM";
+			break;
+		case CMD_DB_HW_BCM:
+			name = "BCM";
+			break;
+		default:
+			name = "Unknown";
+			break;
+		}
+
+		version = le16_to_cpu(rsc->version);
+		major = version >> 8;
+		minor = version;
+
+		seq_printf(seq, "Slave %s (v%u.%u)\n", name, major, minor);
+		seq_puts(seq, "-------------------------\n");
+
+		ent = rsc_to_entry_header(rsc);
+		for (j = 0; j < le16_to_cpu(rsc->cnt); j++, ent++) {
+			seq_printf(seq, "0x%08x: %*pEp", le32_to_cpu(ent->addr),
+				   sizeof(ent->id), ent->id);
+
+			len = le16_to_cpu(ent->len);
+			if (len) {
+				seq_printf(seq, " [%*ph]",
+					   len, rsc_offset(rsc, ent));
+			}
+			seq_putc(seq, '\n');
+		}
+	}
+
+	return 0;
+}
+
+static int open_cmd_db_debugfs(struct inode *inode, struct file *file)
+{
+	return single_open(file, cmd_db_debugfs_dump, inode->i_private);
+}
+#endif
+
+static const struct file_operations cmd_db_debugfs_ops = {
+#ifdef CONFIG_DEBUG_FS
+	.open = open_cmd_db_debugfs,
+#endif
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = single_release,
+};
+
 static int cmd_db_dev_probe(struct platform_device *pdev)
 {
 	struct reserved_mem *rmem;
@@ -259,12 +331,14 @@ static int cmd_db_dev_probe(struct platform_device *pdev)
 		return -EINVAL;
 	}
 
+	debugfs_create_file("cmd-db", 0400, NULL, NULL, &cmd_db_debugfs_ops);
+
 	return 0;
 }
 
 static const struct of_device_id cmd_db_match_table[] = {
 	{ .compatible = "qcom,cmd-db" },
-	{ },
+	{ }
 };
 
 static struct platform_driver cmd_db_dev_driver = {