Add c2 port support

C2port implements a two wire serial communication protocol (bit
banging) designed to enable in-system programming, debugging, and
boundary-scan testing on low pin-count Silicon Labs devices.

Currently this code supports only flash programming through sysfs
interface but extensions shoud be easy to add.
Signed-off-by: NRodolfo Giometti <giometti@linux.it>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Documentation/ABI/testing/sysfs-c2port

+What:		/sys/class/c2port/
+Date:		October 2008
+Contact:	Rodolfo Giometti <giometti@linux.it>
+Description:
+		The /sys/class/c2port/ directory will contain files and
+		directories that will provide a unified interface to
+		the C2 port interface.
+
+What:		/sys/class/c2port/c2portX
+Date:		October 2008
+Contact:	Rodolfo Giometti <giometti@linux.it>
+Description:
+		The /sys/class/c2port/c2portX/ directory is related to X-th
+		C2 port into the system. Each directory will contain files to
+		manage and control its C2 port.
+
+What:		/sys/class/c2port/c2portX/access
+Date:		October 2008
+Contact:	Rodolfo Giometti <giometti@linux.it>
+Description:
+		The /sys/class/c2port/c2portX/access file enable the access
+		to the C2 port from the system. No commands can be sent
+		till this entry is set to 0.
+
+What:		/sys/class/c2port/c2portX/dev_id
+Date:		October 2008
+Contact:	Rodolfo Giometti <giometti@linux.it>
+Description:
+		The /sys/class/c2port/c2portX/dev_id file show the device ID
+		of the connected micro.
+
+What:		/sys/class/c2port/c2portX/flash_access
+Date:		October 2008
+Contact:	Rodolfo Giometti <giometti@linux.it>
+Description:
+		The /sys/class/c2port/c2portX/flash_access file enable the
+		access to the on-board flash of the connected micro.
+		No commands can be sent till this entry is set to 0.
+
+What:		/sys/class/c2port/c2portX/flash_block_size
+Date:		October 2008
+Contact:	Rodolfo Giometti <giometti@linux.it>
+Description:
+		The /sys/class/c2port/c2portX/flash_block_size file show
+		the on-board flash block size of the connected micro.
+
+What:		/sys/class/c2port/c2portX/flash_blocks_num
+Date:		October 2008
+Contact:	Rodolfo Giometti <giometti@linux.it>
+Description:
+		The /sys/class/c2port/c2portX/flash_blocks_num file show
+		the on-board flash blocks number of the connected micro.
+
+What:		/sys/class/c2port/c2portX/flash_data
+Date:		October 2008
+Contact:	Rodolfo Giometti <giometti@linux.it>
+Description:
+		The /sys/class/c2port/c2portX/flash_data file export
+		the content of the on-board flash of the connected micro.
+
+What:		/sys/class/c2port/c2portX/flash_erase
+Date:		October 2008
+Contact:	Rodolfo Giometti <giometti@linux.it>
+Description:
+		The /sys/class/c2port/c2portX/flash_erase file execute
+		the "erase" command on the on-board flash of the connected
+		micro.
+
+What:		/sys/class/c2port/c2portX/flash_erase
+Date:		October 2008
+Contact:	Rodolfo Giometti <giometti@linux.it>
+Description:
+		The /sys/class/c2port/c2portX/flash_erase file show the
+		on-board flash size of the connected micro.
+
+What:		/sys/class/c2port/c2portX/reset
+Date:		October 2008
+Contact:	Rodolfo Giometti <giometti@linux.it>
+Description:
+		The /sys/class/c2port/c2portX/reset file execute a "reset"
+		command on the connected micro.
+
+What:		/sys/class/c2port/c2portX/rev_id
+Date:		October 2008
+Contact:	Rodolfo Giometti <giometti@linux.it>
+Description:
+		The /sys/class/c2port/c2portX/rev_id file show the revision ID
+		of the connected micro.

Documentation/c2port.txt

+			C2 port support
+			---------------
+
+(C) Copyright 2007 Rodolfo Giometti <giometti@enneenne.com>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+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.
+
+
+
+Overview
+--------
+
+This driver implements the support for Linux of Silicon Labs (Silabs)
+C2 Interface used for in-system programming of micro controllers.
+
+By using this driver you can reprogram the in-system flash without EC2
+or EC3 debug adapter. This solution is also useful in those systems
+where the micro controller is connected via special GPIOs pins.
+
+References
+----------
+
+The C2 Interface main references are at (http://www.silabs.com)
+Silicon Laboratories site], see:
+
+- AN127: FLASH Programming via the C2 Interface at
+http://www.silabs.com/public/documents/tpub_doc/anote/Microcontrollers/Small_Form_Factor/en/an127.pdf, and
+
+- C2 Specification at
+http://www.silabs.com/public/documents/tpub_doc/spec/Microcontrollers/en/C2spec.pdf,
+
+however it implements a two wire serial communication protocol (bit
+banging) designed to enable in-system programming, debugging, and
+boundary-scan testing on low pin-count Silicon Labs devices. Currently
+this code supports only flash programming but extensions are easy to
+add.
+
+Using the driver
+----------------
+
+Once the driver is loaded you can use sysfs support to get C2port's
+info or read/write in-system flash.
+
+# ls /sys/class/c2port/c2port0/
+access            flash_block_size  flash_erase       rev_id
+dev_id            flash_blocks_num  flash_size        subsystem/
+flash_access      flash_data        reset             uevent
+
+Initially the C2port access is disabled since you hardware may have
+such lines multiplexed with other devices so, to get access to the
+C2port, you need the command:
+
+# echo 1 > /sys/class/c2port/c2port0/access
+
+after that you should read the device ID and revision ID of the
+connected micro controller:
+
+# cat /sys/class/c2port/c2port0/dev_id
+8
+# cat /sys/class/c2port/c2port0/rev_id
+1
+
+However, for security reasons, the in-system flash access in not
+enabled yet, to do so you need the command:
+
+# echo 1 > /sys/class/c2port/c2port0/flash_access
+
+After that you can read the whole flash:
+
+# cat /sys/class/c2port/c2port0/flash_data > image
+
+erase it:
+
+# echo 1 > /sys/class/c2port/c2port0/flash_erase
+
+and write it:
+
+# cat image > /sys/class/c2port/c2port0/flash_data
+
+after writing you have to reset the device to execute the new code:
+
+# echo 1 > /sys/class/c2port/c2port0/reset

drivers/misc/Kconfig

@@ -498,4 +498,6 @@ config SGI_GRU_DEBUG
 	This option enables addition debugging code for the SGI GRU driver. If
 	you are unsure, say N.
 
+source "drivers/misc/c2port/Kconfig"
+
 endif # MISC_DEVICES

drivers/misc/Makefile

@@ -32,3 +32,4 @@ obj-$(CONFIG_KGDB_TESTS)	+= kgdbts.o
 obj-$(CONFIG_SGI_XP)		+= sgi-xp/
 obj-$(CONFIG_SGI_GRU)		+= sgi-gru/
 obj-$(CONFIG_HP_ILO)		+= hpilo.o
+obj-$(CONFIG_C2PORT)		+= c2port/

drivers/misc/c2port/Kconfig

+#
+# C2 port devices
+#
+
+menuconfig C2PORT
+	tristate "Silicon Labs C2 port support (EXPERIMENTAL)"
+	depends on EXPERIMENTAL
+	default no
+	help
+	  This option enables support for Silicon Labs C2 port used to
+	  program Silicon micro controller chips (and other 8051 compatible).
+
+	  If your board have no such micro controllers you don't need this
+	  interface at all.
+
+	  To compile this driver as a module, choose M here: the module will
+	  be called c2port_core. Note that you also need a client module
+	  usually called c2port-*.
+
+	  If you are not sure, say N here.
+
+if C2PORT
+
+endif # C2PORT

drivers/misc/c2port/Makefile

+obj-$(CONFIG_C2PORT)		+= core.o

include/linux/c2port.h

+/*
+ *  Silicon Labs C2 port Linux support
+ *
+ *  Copyright (c) 2007 Rodolfo Giometti <giometti@linux.it>
+ *  Copyright (c) 2007 Eurotech S.p.A. <info@eurotech.it>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation
+ */
+
+#include <linux/device.h>
+
+#define C2PORT_NAME_LEN			32
+
+/*
+ * C2 port basic structs
+ */
+
+/* Main struct */
+struct c2port_ops;
+struct c2port_device {
+	unsigned int access:1;
+	unsigned int flash_access:1;
+
+	int id;
+	char name[C2PORT_NAME_LEN];
+	struct c2port_ops *ops;
+	struct mutex mutex;		/* prevent races during read/write */
+
+	struct device *dev;
+
+	void *private_data;
+};
+
+/* Basic operations */
+struct c2port_ops {
+	/* Flash layout */
+	unsigned short block_size;	/* flash block size in bytes */
+	unsigned short blocks_num;	/* flash blocks number */
+
+	/* Enable or disable the access to C2 port */
+	void (*access)(struct c2port_device *dev, int status);
+
+	/* Set C2D data line as input/output */
+	void (*c2d_dir)(struct c2port_device *dev, int dir);
+
+	/* Read/write C2D data line */
+	int (*c2d_get)(struct c2port_device *dev);
+	void (*c2d_set)(struct c2port_device *dev, int status);
+
+	/* Write C2CK clock line */
+	void (*c2ck_set)(struct c2port_device *dev, int status);
+};
+
+/*
+ * Exported functions
+ */
+
+#define to_class_dev(obj) container_of((obj), struct class_device, kobj)
+#define to_c2port_device(obj) container_of((obj), struct c2port_device, class)
+
+extern struct c2port_device *c2port_device_register(char *name,
+					struct c2port_ops *ops, void *devdata);
+extern void c2port_device_unregister(struct c2port_device *dev);