usb: gadget: Move diag dload handling to f_diag driver

Upon Diag function bind, the DLOAD memory region should be
updated with the USB PID and serial number in order to support
a persistent connection with the PC if the device reboots into
download mode.

This functionality need not be handled in the android.c driver.
The only reason it is there is to be able to locate the IO address
which is specified in device tree. Since this can be done from
the Diag function driver directly, move the handling there.

The address itself can be specified under the "qcom,msm-imem"
parent with its own "qcom,msm-imem-diag-dload" compatible string.
For now, allow falling back to retrieving the address from the
"android_usb" for backwards compatibility until the device tree
files are updated.

Change-Id: I0d6d1dac0f12b7890220d857227ae45c9258c1f2
Signed-off-by: Jack Pham <jackp@codeaurora.org>

Documentation/devicetree/bindings/arm/msm/imem.txt

@@ -57,6 +57,15 @@ Emergency Download Mode:
 -compatible: "qcom,msm-imem-emergency_download_mode"
 -reg: start address and size of emergency_download_mode region in imem
 
+USB Diag Cookies:
+-----------------
+Memory region used to store USB PID and serial numbers to be used by
+bootloader in download mode.
+
+Required properties:
+-compatible: "qcom,msm-imem-diag-dload"
+-reg: start address and size of USB Diag download mode region in imem
+
 Example:
 
 	qcom,msm-imem {

drivers/usb/gadget/function/f_diag.c

@@ -2,7 +2,7 @@
  * Diag Function Device - Route ARM9 and ARM11 DIAG messages
  * between HOST and DEVICE.
  * Copyright (C) 2007 Google, Inc.
- * Copyright (c) 2008-2015, The Linux Foundation. All rights reserved.
+ * Copyright (c) 2008-2016, The Linux Foundation. All rights reserved.
  * Author: Brian Swetland <swetland@google.com>
  * This software is licensed under the terms of the GNU General Public
  * License version 2, as published by the Free Software Foundation, and
@@ -18,6 +18,7 @@
 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/kref.h>
+#include <linux/of_address.h>
 #include <linux/platform_device.h>
 #include <linux/ratelimit.h>
 
@@ -27,10 +28,13 @@
 #include <linux/workqueue.h>
 #include <linux/debugfs.h>
 #include <linux/kmemleak.h>
+#include <linux/qcom/diag_dload.h>
 
 static DEFINE_SPINLOCK(ch_lock);
 static LIST_HEAD(usb_diag_ch_list);
 
+static struct dload_struct __iomem *diag_dload;
+
 static struct usb_interface_descriptor intf_desc = {
 	.bLength            =	sizeof intf_desc,
 	.bDescriptorType    =	USB_DT_INTERFACE,
@@ -154,7 +158,6 @@ struct diag_context {
 	spinlock_t lock;
 	unsigned configured;
 	struct usb_composite_dev *cdev;
-	int (*update_pid_and_serial_num)(uint32_t, const char *);
 	struct usb_diag_ch *ch;
 	struct kref kref;
 
@@ -189,36 +192,48 @@ static void diag_update_pid_and_serial_num(struct diag_context *ctxt)
 	struct usb_composite_dev *cdev = ctxt->cdev;
 	struct usb_gadget_strings *table;
 	struct usb_string *s;
-
-	if (!ctxt->update_pid_and_serial_num)
-		return;
+	struct dload_struct local_diag_dload = { 0 };
 
 	/*
-	 * update pid and serail number to dload only if diag
+	 * update pid and serial number to dload only if diag
 	 * interface is zeroth interface.
 	 */
 	if (intf_desc.bInterfaceNumber)
 		return;
 
-	/* pass on product id and serial number to dload */
-	if (!cdev->desc.iSerialNumber) {
-		ctxt->update_pid_and_serial_num(
-					cdev->desc.idProduct, 0);
+	if (!diag_dload) {
+		pr_debug("%s: unable to update PID and serial_no\n", __func__);
 		return;
 	}
 
-	/*
-	 * Serial number is filled by the composite driver. So
-	 * it is fair enough to assume that it will always be
-	 * found at first table of strings.
-	 */
-	table = *(cdev->driver->strings);
-	for (s = table->strings; s && s->s; s++)
-		if (s->id == cdev->desc.iSerialNumber) {
-			ctxt->update_pid_and_serial_num(
-					cdev->desc.idProduct, s->s);
-			break;
+	/* update pid */
+	local_diag_dload.magic_struct.pid = PID_MAGIC_ID;
+	local_diag_dload.pid = cdev->desc.idProduct;
+
+	/* pass on product id and serial number to dload */
+	if (cdev->desc.iSerialNumber) {
+		/*
+		 * Serial number is filled by the composite driver. So
+		 * it is fair enough to assume that it will always be
+		 * found at first table of strings.
+		 */
+		table = *(cdev->driver->strings);
+		for (s = table->strings; s && s->s; s++) {
+			if (s->id == cdev->desc.iSerialNumber) {
+				local_diag_dload.magic_struct.serial_num =
+					SERIAL_NUM_MAGIC_ID;
+				strlcpy(local_diag_dload.serial_number, s->s,
+					SERIAL_NUMBER_LENGTH);
+				break;
+			}
 		}
+	}
+
+	pr_debug("%s: dload:%p pid:%x serial_num:%s\n",
+				__func__, diag_dload, local_diag_dload.pid,
+				local_diag_dload.serial_number);
+
+	memcpy_toio(diag_dload, &local_diag_dload, sizeof(local_diag_dload));
 }
 
 static void diag_write_complete(struct usb_ep *ep,
@@ -767,7 +782,12 @@ static int diag_function_bind(struct usb_configuration *c,
 		if (!f->ss_descriptors)
 			goto fail;
 	}
-	diag_update_pid_and_serial_num(ctxt);
+
+	/* Allow only first diag channel to update pid and serial no */
+	if (ctxt == list_first_entry(&diag_dev_list,
+				struct diag_context, list_item))
+		diag_update_pid_and_serial_num(ctxt);
+
 	return 0;
 fail:
 	if (f->ss_descriptors)
@@ -784,8 +804,7 @@ fail:
 
 }
 
-int diag_function_add(struct usb_configuration *c, const char *name,
-			int (*update_pid)(uint32_t, const char *))
+int diag_function_add(struct usb_configuration *c, const char *name)
 {
 	struct diag_context *dev;
 	struct usb_diag_ch *_ch;
@@ -818,7 +837,6 @@ int diag_function_add(struct usb_configuration *c, const char *name,
 	 */
 	dev->ch = _ch;
 
-	dev->update_pid_and_serial_num = update_pid;
 	dev->cdev = c->cdev;
 	dev->function.name = _ch->name;
 	dev->function.fs_descriptors = fs_diag_desc;
@@ -941,6 +959,9 @@ static void diag_cleanup(void)
 	struct usb_diag_ch *_ch;
 	unsigned long flags;
 
+	if (diag_dload)
+		iounmap(diag_dload);
+
 	fdiag_debugfs_remove();
 
 	list_for_each_safe(act, tmp, &usb_diag_ch_list) {
@@ -958,9 +979,21 @@ static void diag_cleanup(void)
 
 static int diag_setup(void)
 {
+	struct device_node *np;
+
 	INIT_LIST_HEAD(&diag_dev_list);
 
 	fdiag_debugfs_init();
 
+	np = of_find_compatible_node(NULL, NULL, "qcom,msm-imem-diag-dload");
+	if (!np)
+		np = of_find_compatible_node(NULL, NULL, "qcom,android-usb");
+
+	if (!np) {
+		pr_warn("diag: failed to find diag_dload imem node\n");
+		return 0;
+	}
+	diag_dload = of_iomap(np, 0);
+
 	return 0;
 }

include/linux/qcom/diag_dload.h

@@ -0,0 +1,32 @@
+/* Copyright (c) 2012, The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef __LINUX_DIAG_DLOAD_H__
+#define __LINUX_DIAG_DLOAD_H__
+
+
+#define PID_MAGIC_ID		0x71432909
+#define SERIAL_NUM_MAGIC_ID	0x61945374
+#define SERIAL_NUMBER_LENGTH	128
+
+struct magic_num_struct {
+	uint32_t pid;
+	uint32_t serial_num;
+};
+
+struct dload_struct {
+	uint32_t	pid;
+	char		serial_number[SERIAL_NUMBER_LENGTH];
+	struct magic_num_struct magic_struct;
+};
+
+#endif