[PATCH] drivers, char: add U-Boot bootcount driver
Matthias Kaehlcke
matthias at kaehlcke.net
Sun Dec 4 22:05:46 EST 2011
hi,
some comments inline
El Sun, Dec 04, 2011 at 10:45:21AM +0100 Heiko Schocher ha dit:
> 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 at 0x23060 {
> 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 at denx.de>
> Cc: Wolfgang Denk <wd at denx.de>
> Cc: Vitaly Bordug <vbordug at ru.mvista.com>
> Cc: devicetree-discuss at lists.ozlabs.org
> Cc: linux-kernel at vger.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 at 1c23000 {
> + 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 at denx.de>
> + * Based on work from: Steffen Rumler (Steffen.Rumler at siemens.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;
+static 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;
> +
> +
remove second empty line
> + 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);
> + }
no need for curly braces
> +
> + 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;
> +
> +
remove second empty line
> + *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__);
return -1; ?
also applies to other error paths in this function. carrying on
without the register mapped or without access to the bootcounter
doesn't seem to make much sense
> +
> + /* 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 at siemens.com>");
> +MODULE_DESCRIPTION("Provide (read/write) access to the U-Boot bootcounter via PROC FS");
--
Matthias Kaehlcke
Embedded Linux Developer
Amsterdam
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