Date:	Sun,  4 Dec 2011 10:45:21 +0100
From:	Heiko Schocher <hs@...x.de>
To:	unlisted-recipients:; (no To-header on input)
Cc:	Heiko Schocher <hs@...x.de>, Wolfgang Denk <wd@...x.de>,
	Vitaly Bordug <vbordug@...mvista.com>,
	devicetree-discuss@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: [PATCH] drivers, char: add U-Boot bootcount driver

This driver implements the Linux kernel half of the boot count feature -
the boot counter can only be reset after it is clear that the
application has been started and is running correctly, which usually
can only be determined by the application code itself. Thus the reset
of the boot counter must be done by application code, which thus needs
an appropriate driver.

Required feature by the Carrier Grade Linux Requirements Definition;
see for example document "Carrier Grade Linux Requirements Definition
Overview V3.0" at

http://www.linuxfoundation.org/collaborate/workgroups/cgl/requirements#SMM.6.0_Boot_Cycle_Detection

        Description: OSDL CGL specifies that carrier grade Linux
        shall provide support for detecting a repeating reboot cycle
	due to recurring failures. This detection should happen in
	user space before system services are started.

This driver provides read/write access to the U-Boot bootcounter
through PROC FS and/or sysFS file.

The bootcountregister gets configured via DTS.
for example on the enbw_cmc board:

bootcount@...3060 {
                  compatible = "uboot,bootcount";
                  reg = <0x23060 0x20>;
                 };

original post from:
http://old.nabble.com/-POWERPC--add-U-Boot-bootcount-driver.-td26804029.html

Signed-off-by: Heiko Schocher <hs@...x.de>
Cc: Wolfgang Denk <wd@...x.de>
Cc: Vitaly Bordug <vbordug@...mvista.com>
Cc: devicetree-discuss@...ts.ozlabs.org
Cc: linux-kernel@...r.kernel.org
---
 .../devicetree/bindings/char/bootcount.txt         |   13 ++
 drivers/char/Kconfig                               |    7 +
 drivers/char/Makefile                              |    1 +
 drivers/char/bootcount.c                           |  210 ++++++++++++++++++++
 4 files changed, 231 insertions(+), 0 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/char/bootcount.txt
 create mode 100644 drivers/char/bootcount.c

diff --git a/Documentation/devicetree/bindings/char/bootcount.txt b/Documentation/devicetree/bindings/char/bootcount.txt
new file mode 100644
index 0000000..079a7da
--- /dev/null
+++ b/Documentation/devicetree/bindings/char/bootcount.txt
@@ -0,0 +1,13 @@
+Bootcount driver
+
+Required properties:
+
+  - compatible : should be "uboot,bootcount"
+  - reg: the address of the bootcounter
+
+Example:
+
+bootcount@...3000 {
+	compatible = "uboot,bootcount";
+	reg = <0x23060 0x20>;
+};
diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
index 4364303..9c5ccab 100644
--- a/drivers/char/Kconfig
+++ b/drivers/char/Kconfig
@@ -577,6 +577,13 @@ config UV_MMTIMER
 	  The uv_mmtimer device allows direct userspace access to the
 	  UV system timer.
 
+config BOOTCOUNT
+	tristate "U-Boot Bootcount driver"
+	depends on OF
+	help
+	  The U-Boot Bootcount driver allows to access the
+	  bootcounter through procFS or sysFS files.
+
 source "drivers/char/tpm/Kconfig"
 
 config TELCLOCK
diff --git a/drivers/char/Makefile b/drivers/char/Makefile
index 32762ba..a91e18e 100644
--- a/drivers/char/Makefile
+++ b/drivers/char/Makefile
@@ -49,6 +49,7 @@ obj-$(CONFIG_PC8736x_GPIO)	+= pc8736x_gpio.o
 obj-$(CONFIG_NSC_GPIO)		+= nsc_gpio.o
 obj-$(CONFIG_GPIO_TB0219)	+= tb0219.o
 obj-$(CONFIG_TELCLOCK)		+= tlclk.o
+obj-$(CONFIG_BOOTCOUNT)		+= bootcount.o
 
 obj-$(CONFIG_MWAVE)		+= mwave/
 obj-$(CONFIG_AGP)		+= agp/
diff --git a/drivers/char/bootcount.c b/drivers/char/bootcount.c
new file mode 100644
index 0000000..0ee457f
--- /dev/null
+++ b/drivers/char/bootcount.c
@@ -0,0 +1,210 @@
+/*
+ * This driver gives access(read/write) to the bootcounter used by u-boot.
+ * Access is supported via procFS and sysFS.
+ *
+ * Copyright 2008 DENX Software Engineering GmbH
+ * Author: Heiko Schocher <hs@...x.de>
+ * Based on work from: Steffen Rumler  (Steffen.Rumler@...mens.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.
+ */
+
+#include <linux/capability.h>
+#include <linux/device.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/mm.h>
+#include <linux/mman.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_device.h>
+#include <linux/of_platform.h>
+#include <linux/ptrace.h>
+#include <linux/uaccess.h>
+
+#ifndef CONFIG_PROC_FS
+#error "PROC FS support must be switched-on"
+#endif
+#include <linux/proc_fs.h>
+
+#define	UBOOT_BOOTCOUNT_MAGIC_OFFSET	0x04	/* offset of magic number */
+#define	UBOOT_BOOTCOUNT_MAGIC		0xB001C041 /* magic number value */
+
+#define	UBOOT_BOOTCOUNT_PROC_ENTRY	"driver/bootcount"
+
+/*
+ * This macro frees the machine specific function from bounds checking and
+ * this like that...
+ */
+#define PRINT_PROC(fmt, args...) \
+	do { \
+		*len += sprintf(buffer + *len, fmt, ##args); \
+		if (*begin + *len > offset + size) \
+			return 0; \
+		if (*begin + *len < offset) { \
+			*begin += *len; \
+			*len = 0; \
+		} \
+	} while (0)
+
+void __iomem *mem;
+/*
+ * read U-Boot bootcounter
+ */
+static int
+read_bootcounter_info(char *buffer, int *len, off_t * begin, off_t offset,
+		       int size)
+{
+	unsigned long magic;
+	unsigned long counter;
+
+
+	magic = be32_to_cpu(readl(mem + UBOOT_BOOTCOUNT_MAGIC_OFFSET));
+	counter = be32_to_cpu(readl(mem));
+
+	if (magic == UBOOT_BOOTCOUNT_MAGIC) {
+		PRINT_PROC("%lu\n", counter);
+	} else {
+		PRINT_PROC("bad magic: 0x%lu != 0x%lu\n", magic,
+			    (unsigned long)UBOOT_BOOTCOUNT_MAGIC);
+	}
+
+	return 1;
+}
+
+/*
+ * read U-Boot bootcounter (wrapper)
+ */
+static int
+read_bootcounter(char *buffer, char **start, off_t offset, int size,
+		  int *eof, void *arg)
+{
+	int len = 0;
+	off_t begin = 0;
+
+
+	*eof = read_bootcounter_info(buffer, &len, &begin, offset, size);
+
+	if (offset >= begin + len)
+		return 0;
+
+	*start = buffer + (offset - begin);
+	return size < begin + len - offset ? size : begin + len - offset;
+}
+
+/*
+ * write new value to U-Boot bootcounter
+ */
+static int
+write_bootcounter(struct file *file, const char *buffer, unsigned long count,
+		   void *data)
+{
+	unsigned long magic;
+
+	magic = be32_to_cpu(readl(mem + UBOOT_BOOTCOUNT_MAGIC_OFFSET));
+	if (magic == UBOOT_BOOTCOUNT_MAGIC)
+		writel(cpu_to_be32(simple_strtol(buffer, NULL, 10)), mem);
+	else
+		return -EINVAL;
+
+	return count;
+}
+
+/* helper for the sysFS */
+static int show_str_bootcount(struct device *device,
+				struct device_attribute *attr,
+				char *buf)
+{
+	int ret = 0;
+	off_t begin = 0;
+
+	read_bootcounter_info(buf, &ret, &begin, 0, 20);
+	return ret;
+}
+static int store_str_bootcount(struct device *dev,
+			struct device_attribute *attr,
+			const char *buf,
+			size_t count)
+{
+	write_bootcounter(NULL, buf, count, NULL);
+	return count;
+}
+static DEVICE_ATTR(bootcount, S_IWUSR | S_IRUGO, show_str_bootcount,
+		store_str_bootcount);
+
+static int __devinit bootcount_probe(struct platform_device *ofdev)
+{
+	struct device_node *np = of_node_get(ofdev->dev.of_node);
+	struct proc_dir_entry *bootcount;
+
+	mem = of_iomap(np, 0);
+	if (mem == NULL)
+		dev_err(&ofdev->dev, "%s couldnt map register.\n", __func__);
+
+	/* init ProcFS */
+	bootcount = create_proc_entry(UBOOT_BOOTCOUNT_PROC_ENTRY, 0600, NULL);
+	if (bootcount == NULL) {
+		dev_err(&ofdev->dev, "\n%s (%d): cannot create /proc/%s\n",
+			__FILE__, __LINE__, UBOOT_BOOTCOUNT_PROC_ENTRY);
+	} else {
+
+		bootcount->read_proc = read_bootcounter;
+		bootcount->write_proc = write_bootcounter;
+		dev_info(&ofdev->dev, "created \"/proc/%s\"\n",
+			UBOOT_BOOTCOUNT_PROC_ENTRY);
+	}
+
+	if (device_create_file(&ofdev->dev, &dev_attr_bootcount))
+		dev_warn(&ofdev->dev, "%s couldnt register sysFS entry.\n",
+			__func__);
+
+	return 0;
+}
+
+static int __devexit bootcount_remove(struct platform_device *ofdev)
+{
+	BUG();
+	return 0;
+}
+
+static const struct of_device_id __devinitconst bootcount_match[] = {
+	{
+		.compatible = "uboot,bootcount",
+	},
+	{},
+};
+MODULE_DEVICE_TABLE(of, bootcount_match);
+
+static struct platform_driver bootcount_driver = {
+	.driver = {
+		.name = "bootcount",
+		.of_match_table = bootcount_match,
+		.owner = THIS_MODULE,
+	},
+	.probe = bootcount_probe,
+	.remove = bootcount_remove,
+};
+
+
+static int __init uboot_bootcount_init(void)
+{
+	return platform_driver_register(&bootcount_driver);
+}
+
+static void __exit uboot_bootcount_cleanup(void)
+{
+	if (mem != NULL)
+		iounmap(mem);
+	remove_proc_entry(UBOOT_BOOTCOUNT_PROC_ENTRY, NULL);
+}
+
+module_init(uboot_bootcount_init);
+module_exit(uboot_bootcount_cleanup);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Steffen Rumler <steffen.rumler@...mens.com>");
+MODULE_DESCRIPTION("Provide (read/write) access to the U-Boot bootcounter via PROC FS");
-- 
1.7.6.4

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