[RFC 1/2] firmware class: Add stream_firmware API.

[yi1.li@linux.intel.com]

From: Yi Li <yi1.li@linux.intel.com>

Add function to load firmware in multiple chucks instead of

loading the whole big firmware file at once.

Signed-off-by: Yi Li <yi1.li@linux.intel.com>
---
 drivers/base/firmware_class.c | 128 ++++++++++++++++++++++++++++++++++++++++++
 include/linux/firmware.h      |   2 +
 2 files changed, 130 insertions(+)

diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index ac350c5..44fddff 100644
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -436,6 +436,62 @@ fw_get_filesystem_firmware(struct device *device, struct firmware_buf *buf)
 	return rc;
 }
 
+static int
+fw_stream_filesystem_firmware(struct device *device, struct firmware_buf *buf,
+			size_t offset, size_t length)
+{
+	int i, len;
+	char *path;
+	int rc = 0;
+	struct file *file;
+
+	buf->size = 0;
+
+	path = __getname();
+	if (!path)
+		return -ENOMEM;
+
+	for (i = 0; i < ARRAY_SIZE(fw_path); i++) {
+		/* skip the unset customized path */
+		if (!fw_path[i][0])
+			continue;
+
+		len = snprintf(path, PATH_MAX, "%s/%s",
+			       fw_path[i], buf->fw_id);
+		if (len >= PATH_MAX) {
+			rc = -ENAMETOOLONG;
+			break;
+		}
+
+		if (!path || !*path)
+			continue;
+
+		if (!buf->data) {
+			buf->data = vmalloc(length);
+			if (!buf->data) {
+				rc = -ENOMEM;
+				break;
+			}
+		}
+
+		file = filp_open(path, O_RDONLY, 0);
+		if (IS_ERR(file))
+			continue;
+
+		buf->size = kernel_read(file, offset, (char *) buf->data,
+					length);
+		fput(file);
+		break;
+	}
+
+	__putname(path);
+
+	if (rc)
+		dev_err(device, "loading %s failed with error %d\n",
+			 path, rc);
+	return rc;
+}
+
 /* firmware holds the ownership of pages */
 static void firmware_free_data(const struct firmware *fw)
 {
@@ -1267,6 +1323,78 @@ request_firmware(const struct firmware **firmware_p, const char *name,
 }
 EXPORT_SYMBOL(request_firmware);
 
+static int
+_stream_firmware(const struct firmware **firmware_p, const char *name,
+		  struct device *device, void *buf, size_t size,
+		  unsigned int opt_flags, size_t offset, size_t length)
+{
+	int ret;
+	struct firmware *fw = NULL;
+	struct firmware_buf *fbuf;
+
+	if ((!firmware_p) || (!name || name[0] == '\0')) {
+		dev_err(device, "invalid firmware pointer or file name\n");
+		return -EINVAL;
+	}
+
+	if (!*firmware_p) {
+		ret = _request_firmware_prepare(&fw, name, device, buf, size);
+		if (ret <= 0) {
+			dev_err(device, "%s: _request_firmware_prepare failed %d\n",
+				__func__, ret);
+		}
+	} else {
+		fw = (struct firmware *) *firmware_p;
+	}
+
+	fbuf = (struct firmware_buf *) fw->priv;
+	ret = fw_stream_filesystem_firmware(device, fbuf, offset, length);
+	fw->size = fbuf->size;
+	fw->data = fbuf->data;
+	*firmware_p = fw;
+
+	if (ret)
+		dev_err(device, "streaming with error %d\n", ret);
+	return ret;
+}
+
+/**
+ * stream_firmware: - send firmware request and wait for it
+ * @firmware_p: pointer to firmware image
+ * @name: name of firmware file
+ * @device: device for which firmware is being loaded
+ * @offset: offset of the file to read from
+ * @length: length in bytes to read
+ *
+ *      @firmware_p will be used to return a firmware image by the name
+ *      of @name for device @device.
+ *
+ *      Should be called from user context where sleeping is allowed.
+ *
+ *      @name will be used as $FIRMWARE in the uevent environment and
+ *      should be distinctive enough not to be confused with any other
+ *      firmware image for this or any other device.
+ *
+ *	Caller must hold the reference count of @device.
+ *
+ *	The function can be called safely inside device's suspend and
+ *	resume callback.
+ **/
+int
+stream_firmware(const struct firmware **firmware_p, const char *name,
+		 struct device *device, size_t offset, size_t length)
+{
+	size_t ret;
+
+	/* Need to pin this module until return */
+	__module_get(THIS_MODULE);
+	ret = _stream_firmware(firmware_p, name, device, NULL, 0,
+				FW_OPT_UEVENT | FW_OPT_NO_WARN, offset, length);
+	module_put(THIS_MODULE);
+	return ret;
+}
+EXPORT_SYMBOL(stream_firmware);
+
 /**
  * request_firmware_direct: - load firmware directly without usermode helper
  * @firmware_p: pointer to firmware image
diff --git a/include/linux/firmware.h b/include/linux/firmware.h
index b1f9f0c..accd7f6 100644
--- a/include/linux/firmware.h
+++ b/include/linux/firmware.h
@@ -41,6 +41,8 @@ struct builtin_fw {
 #if defined(CONFIG_FW_LOADER) || (defined(CONFIG_FW_LOADER_MODULE) && defined(MODULE))
 int request_firmware(const struct firmware **fw, const char *name,
 		     struct device *device);
+int stream_firmware(const struct firmware **fw, const char *name,
+		    struct device *device, size_t offset, size_t length);
 int request_firmware_nowait(
 	struct module *module, bool uevent,
 	const char *name, struct device *device, gfp_t gfp, void *context,
-- 
2.7.4