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Commit c0e65d02 authored by Joel Porquet's avatar Joel Porquet Committed by Greg Kroah-Hartman
Browse files

greybus: add support for the log protocol 



Add support for the new Log class/protocol. This protocol allows modules
to send their internal logging messages to the AP in order to make
module debugging easier.

The protocol is, for now, composed a single module-initiated request.
This request contains a message and associated length. The message is
integrated in the kernel log with dev_dbg(). In order to be displayed
with 'dmesg', the following command needs to be entered first:

$ echo "file log.c +p" > /sys/kernel/debug/dynamic_debug/control

The major portion of this file was initially written by Greg KH.

Signed-off-by: default avatarJoel Porquet <porquet_joel@projectara.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@google.com>
parent 6f7f2ae5

drivers/staging/greybus/Makefile

+2 −0
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ gb-gbphy-y := gbphy.o 
# Prefix all modules with gb-

gb-vibrator-y := vibrator.o

gb-power-supply-y := power_supply.o

gb-log-y := log.o

gb-loopback-y := loopback.o

gb-light-y := light.o

gb-raw-y := raw.o
@@ -46,6 +47,7 @@ obj-m += greybus.o 
obj-m += gb-gbphy.o

obj-m += gb-vibrator.o

obj-m += gb-power-supply.o

obj-m += gb-log.o

obj-m += gb-loopback.o

obj-m += gb-light.o

obj-m += gb-hid.o

drivers/staging/greybus/greybus_manifest.h

+2 −0
Original line number Diff line number Diff line
@@ -47,6 +47,7 @@ enum greybus_protocol { 
	GREYBUS_PROTOCOL_CAMERA_DATA	= 0x16,

	GREYBUS_PROTOCOL_FW_DOWNLOAD	= 0x17,

	GREYBUS_PROTOCOL_FW_MANAGEMENT	= 0x18,

	GREYBUS_PROTOCOL_LOG		= 0x1a,

		/* ... */

	GREYBUS_PROTOCOL_RAW		= 0xfe,

	GREYBUS_PROTOCOL_VENDOR		= 0xff,
@@ -76,6 +77,7 @@ enum greybus_class_type { 
	/* 0x14 is unused */

	GREYBUS_CLASS_BOOTROM		= 0x15,

	GREYBUS_CLASS_FW_MANAGEMENT	= 0x16,

	GREYBUS_CLASS_LOG		= 0x17,

		/* ... */

	GREYBUS_CLASS_RAW		= 0xfe,

	GREYBUS_CLASS_VENDOR		= 0xff,

drivers/staging/greybus/greybus_protocols.h

+14 −0
Original line number Diff line number Diff line
@@ -2136,5 +2136,19 @@ struct gb_audio_send_data_request { 
	__u8	data[0];

} __packed;





/* Log */



/* operations */

#define GB_LOG_TYPE_SEND_LOG	0x02



/* length */

#define GB_LOG_MAX_LEN		1024



struct gb_log_send_log_request {

	__le16	len;

	__u8    msg[0];

} __packed;



#endif /* __GREYBUS_PROTOCOLS_H */

drivers/staging/greybus/log.c

0 → 100644
+132 −0
Original line number Diff line number Diff line 
/*

 * Greybus driver for the log protocol

 *

 * Copyright 2016 Google Inc.

 *

 * Released under the GPLv2 only.

 */

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/slab.h>

#include <linux/sizes.h>

#include <linux/uaccess.h>



#include "greybus.h"



struct gb_log {

	struct gb_connection *connection;

};



static int gb_log_request_handler(struct gb_operation *op)

{

	struct gb_connection *connection = op->connection;

	struct device *dev = &connection->bundle->dev;

	struct gb_log_send_log_request *receive;

	u16 len;



	if (op->type != GB_LOG_TYPE_SEND_LOG) {

		dev_err(dev, "unknown request type 0x%02x\n", op->type);

		return -EINVAL;

	}



	/* Verify size of payload */

	if (op->request->payload_size < sizeof(*receive)) {

		dev_err(dev, "log request too small (%zu < %zu)\n",

				op->request->payload_size, sizeof(*receive));

		return -EINVAL;

	}

	receive = op->request->payload;

	len = le16_to_cpu(receive->len);

	if (len != (int)(op->request->payload_size - sizeof(*receive))) {

		dev_err(dev, "log request wrong size %d vs %d\n", len,

				(int)(op->request->payload_size - sizeof(*receive)));

		return -EINVAL;

	}

	if (len == 0) {

		dev_err(dev, "log request of 0 bytes?\n");

		return -EINVAL;

	}



	if (len > GB_LOG_MAX_LEN) {

		dev_err(dev, "log request too big: %d\n", len);

		return -EINVAL;

	}



	/* Ensure the buffer is 0 terminated */

	receive->msg[len - 1] = '\0';



	/* Print with dev_dbg() so that it can be easily turned off using

	 * dynamic debugging (and prevent any DoS) */

	dev_dbg(dev, "%s", receive->msg);



	return 0;

}



static int gb_log_probe(struct gb_bundle *bundle,

			const struct greybus_bundle_id *id)

{

	struct greybus_descriptor_cport *cport_desc;

	struct gb_connection *connection;

	struct gb_log *log;

	int retval;



	if (bundle->num_cports != 1)

		return -ENODEV;



	cport_desc = &bundle->cport_desc[0];

	if (cport_desc->protocol_id != GREYBUS_PROTOCOL_LOG)

		return -ENODEV;



	log = kzalloc(sizeof(*log), GFP_KERNEL);

	if (!log)

		return -ENOMEM;



	connection = gb_connection_create(bundle, le16_to_cpu(cport_desc->id),

			gb_log_request_handler);

	if (IS_ERR(connection)) {

		retval = PTR_ERR(connection);

		goto error_free;

	}



	log->connection = connection;

	greybus_set_drvdata(bundle, log);



	retval = gb_connection_enable(connection);

	if (retval)

		goto error_connection_destroy;



	return 0;



error_connection_destroy:

	gb_connection_destroy(connection);

error_free:

	kfree(log);

	return retval;

}



static void gb_log_disconnect(struct gb_bundle *bundle)

{

	struct gb_log *log = greybus_get_drvdata(bundle);

	struct gb_connection *connection = log->connection;



	gb_connection_disable(connection);

	gb_connection_destroy(connection);



	kfree(log);

}



static const struct greybus_bundle_id gb_log_id_table[] = {

	{ GREYBUS_DEVICE_CLASS(GREYBUS_CLASS_LOG) },

	{ }

};

MODULE_DEVICE_TABLE(greybus, gb_log_id_table);



static struct greybus_driver gb_log_driver = {

	.name           = "log",

	.probe          = gb_log_probe,

	.disconnect     = gb_log_disconnect,

	.id_table       = gb_log_id_table,

};

module_greybus_driver(gb_log_driver);



MODULE_LICENSE("GPL v2");