thunderbolt: Expose router DROM through debugfs

Router DROM contains information that might be usable for development
and debugging purposes. For example when new entries are added to the
USB4 spec it is useful to be able to look for them without need to
change the kernel.

For this reason expose the DROM through debugfs.

Signed-off-by: Mika Westerberg <[email protected]>

Author: westeri

drivers/thunderbolt/debugfs.c

@@ -2413,6 +2413,8 @@ void tb_switch_debugfs_init(struct tb_switch *sw)
 	sw->debugfs_dir = debugfs_dir;
 	debugfs_create_file("regs", DEBUGFS_MODE, debugfs_dir, sw,
 			    &switch_regs_fops);
+	if (sw->drom)
+		debugfs_create_blob("drom", 0400, debugfs_dir, &sw->drom_blob);
 
 	tb_switch_for_each_port(sw, port) {
 		struct dentry *debugfs_dir;

drivers/thunderbolt/eeprom.c

@@ -435,6 +435,29 @@ static int tb_drom_parse_entries(struct tb_switch *sw, size_t header_size)
 	return 0;
 }
 
+static int tb_switch_drom_alloc(struct tb_switch *sw, size_t size)
+{
+	sw->drom = kzalloc(size, GFP_KERNEL);
+	if (!sw->drom)
+		return -ENOMEM;
+
+#ifdef CONFIG_DEBUG_FS
+	sw->drom_blob.data = sw->drom;
+	sw->drom_blob.size = size;
+#endif
+	return 0;
+}
+
+static void tb_switch_drom_free(struct tb_switch *sw)
+{
+#ifdef CONFIG_DEBUG_FS
+	sw->drom_blob.data = NULL;
+	sw->drom_blob.size = 0;
+#endif
+	kfree(sw->drom);
+	sw->drom = NULL;
+}
+
 /*
  * tb_drom_copy_efi - copy drom supplied by EFI to sw->drom if present
  */
@@ -447,9 +470,9 @@ static int tb_drom_copy_efi(struct tb_switch *sw, u16 *size)
 	if (len < 0 || len < sizeof(struct tb_drom_header))
 		return -EINVAL;
 
-	sw->drom = kmalloc(len, GFP_KERNEL);
-	if (!sw->drom)
-		return -ENOMEM;
+	res = tb_switch_drom_alloc(sw, len);
+	if (res)
+		return res;
 
 	res = device_property_read_u8_array(dev, "ThunderboltDROM", sw->drom,
 									len);
@@ -464,8 +487,7 @@ static int tb_drom_copy_efi(struct tb_switch *sw, u16 *size)
 	return 0;
 
 err:
-	kfree(sw->drom);
-	sw->drom = NULL;
+	tb_switch_drom_free(sw);
 	return -EINVAL;
 }
 
@@ -491,25 +513,22 @@ static int tb_drom_copy_nvm(struct tb_switch *sw, u16 *size)
 
 	/* Size includes CRC8 + UID + CRC32 */
 	*size += 1 + 8 + 4;
-	sw->drom = kzalloc(*size, GFP_KERNEL);
-	if (!sw->drom)
-		return -ENOMEM;
+	ret = tb_switch_drom_alloc(sw, *size);
+	if (ret)
+		return ret;
 
 	ret = dma_port_flash_read(sw->dma_port, drom_offset, sw->drom, *size);
-	if (ret)
-		goto err_free;
+	if (ret) {
+		tb_switch_drom_free(sw);
+		return ret;
+	}
 
 	/*
 	 * Read UID from the minimal DROM because the one in NVM is just
 	 * a placeholder.
 	 */
 	tb_drom_read_uid_only(sw, &sw->uid);
 	return 0;
-
-err_free:
-	kfree(sw->drom);
-	sw->drom = NULL;
-	return ret;
 }
 
 static int usb4_copy_drom(struct tb_switch *sw, u16 *size)
@@ -522,15 +541,13 @@ static int usb4_copy_drom(struct tb_switch *sw, u16 *size)
 
 	/* Size includes CRC8 + UID + CRC32 */
 	*size += 1 + 8 + 4;
-	sw->drom = kzalloc(*size, GFP_KERNEL);
-	if (!sw->drom)
-		return -ENOMEM;
+	ret = tb_switch_drom_alloc(sw, *size);
+	if (ret)
+		return ret;
 
 	ret = usb4_switch_drom_read(sw, 0, sw->drom, *size);
-	if (ret) {
-		kfree(sw->drom);
-		sw->drom = NULL;
-	}
+	if (ret)
+		tb_switch_drom_free(sw);
 
 	return ret;
 }
@@ -552,19 +569,14 @@ static int tb_drom_bit_bang(struct tb_switch *sw, u16 *size)
 		return -EIO;
 	}
 
-	sw->drom = kzalloc(*size, GFP_KERNEL);
-	if (!sw->drom)
-		return -ENOMEM;
+	ret = tb_switch_drom_alloc(sw, *size);
+	if (ret)
+		return ret;
 
 	ret = tb_eeprom_read_n(sw, 0, sw->drom, *size);
 	if (ret)
-		goto err;
-
-	return 0;
+		tb_switch_drom_free(sw);
 
-err:
-	kfree(sw->drom);
-	sw->drom = NULL;
 	return ret;
 }
 
@@ -646,9 +658,7 @@ static int tb_drom_parse(struct tb_switch *sw, u16 size)
 	return 0;
 
 err:
-	kfree(sw->drom);
-	sw->drom = NULL;
-
+	tb_switch_drom_free(sw);
 	return ret;
 }
 

drivers/thunderbolt/tb.h

@@ -9,6 +9,7 @@
 #ifndef TB_H_
 #define TB_H_
 
+#include <linux/debugfs.h>
 #include <linux/nvmem-provider.h>
 #include <linux/pci.h>
 #include <linux/thunderbolt.h>
@@ -160,6 +161,7 @@ struct tb_switch_tmu {
  * @max_pcie_credits: Router preferred number of buffers for PCIe
  * @max_dma_credits: Router preferred number of buffers for DMA/P2P
  * @clx: CLx states on the upstream link of the router
+ * @drom_blob: DROM debugfs blob wrapper
  *
  * When the switch is being added or removed to the domain (other
  * switches) you need to have domain lock held.
@@ -212,6 +214,9 @@ struct tb_switch {
 	unsigned int max_pcie_credits;
 	unsigned int max_dma_credits;
 	unsigned int clx;
+#ifdef CONFIG_DEBUG_FS
+	struct debugfs_blob_wrapper drom_blob;
+#endif
 };
 
 /**