From: "Gabriel Somlo" <[email protected]>
Allow access to QEMU firmware blobs, passed into the guest VM via
the fw_cfg device, through SysFS entries. Blob meta-data (e.g. name,
size, and fw_cfg key), as well as the raw binary blob data may be
accessed.
The SysFS access location is /sys/firmware/qemu_fw_cfg/... and was
selected based on overall similarity to the type of information
exposed under /sys/firmware/dmi/entries/...
New (since v3):
Patch 1/4: Device probing now works with either ACPI, DT, or
optionally by manually specifying a base, size, and
register offsets on the command line. This way, all
architectures offering fw_cfg can be supported, although
x86 and ARM get *automatic* support via ACPI and/or DT.
HUGE thanks to Laszlo Ersek <[email protected]> for
pointing out drivers/virtio/virtio_mmio.c, as an example
on how to pull this off !!!
Stefan: I saw Marc's DMA patches to fw_cfg. Since only
x86 and ARM will support it starting with QEMU 2.5, and
since I expect to get lots of otherwise interesting (but
otherwise orthogonal) feedback on this series, I'd like
to stick with ioread8() across the board for now. We can
always patch in DMA support in a backward compatible way
later, once this series gets (hopefully) accepted :)
Patch 2/4: (was 3/4 in v3): unchanged. Exports kset_find_obj() so
modules can call it.
Patch 3/4: (was 4/4 in v3): rebased, but otherwise the same.
Essentially, creates a "human readable" directory
hierarchy from "path-like" tokens making up fw_cfg
blob names. I'm not really sure there's a way to make
this happen via udev rules, but I have at least one
potential use case for doing it *before* udev becomes
available (cc: Andy Lutomirski <[email protected]>),
so I'd be happy to leave this functionality in the
kernel module. See further below for an illustration
of this.
Patch 4/4: Updates the existing ARM DT documentation for fw_cfg,
mainly by pointing at the more comprehensive document
introduced with Patch 1/4 for details on the fw_cfg
device interface, leaving only the specific ARM/DT
address/size node information in place.
Thanks much,
--Gabriel
> In addition to the "by_key" blob listing, e.g.:
>
> $ tree /sys/firmware/qemu_fw_cfg/
> /sys/firmware/qemu_fw_cfg/
> |-- by_key
> | |-- 32
> | | |-- key
> | | |-- name ("etc/boot-fail-wait")
> | | |-- raw
> | | `-- size
> | |-- 33
> | | |-- key
> | | |-- name ("etc/smbios/smbios-tables")
> | | |-- raw
> | | `-- size
> | |-- 34
> | | |-- key
> | | |-- name ("etc/smbios/smbios-anchor")
> | | |-- raw
> | | `-- size
> | |-- 35
> | | |-- key
> | | |-- name ("etc/e820")
> | | |-- raw
> | | `-- size
> | |-- 36
> | | |-- key
> | | |-- name ("genroms/kvmvapic.bin")
> | | |-- raw
> | | `-- size
> | |-- 37
> | | |-- key
> | | |-- name ("etc/system-states")
> | | |-- raw
> | | `-- size
> | |-- 38
> | | |-- key
> | | |-- name ("etc/acpi/tables")
> | | |-- raw
> | | `-- size
> | |-- 39
> | | |-- key
> | | |-- name ("etc/table-loader")
> | | |-- raw
> | | `-- size
> | |-- 40
> | | |-- key
> | | |-- name ("etc/tpm/log")
> | | |-- raw
> | | `-- size
> | |-- 41
> | | |-- key
> | | |-- name ("etc/acpi/rsdp")
> | | |-- raw
> | | `-- size
> | `-- 42
> | |-- key
> | |-- name ("bootorder")
> | |-- raw
> | `-- size
> |
> ...
>
> Patch 3/4 also gets us a "human readable" "by_name" listing, like so:
>
> ...
> |-- by_name
> | |-- bootorder -> ../by_key/42
> | |-- etc
> | | |-- acpi
> | | | |-- rsdp -> ../../../by_key/41
> | | | `-- tables -> ../../../by_key/38
> | | |-- boot-fail-wait -> ../../by_key/32
> | | |-- e820 -> ../../by_key/35
> | | |-- smbios
> | | | |-- smbios-anchor -> ../../../by_key/34
> | | | `-- smbios-tables -> ../../../by_key/33
> | | |-- system-states -> ../../by_key/37
> | | |-- table-loader -> ../../by_key/39
> | | `-- tpm
> | | `-- log -> ../../../by_key/40
> | `-- genroms
> | `-- kvmvapic.bin -> ../../by_key/36
> `-- rev
Gabriel Somlo (4):
firmware: introduce sysfs driver for QEMU's fw_cfg device
kobject: export kset_find_obj() for module use
firmware: create directory hierarchy for sysfs fw_cfg entries
devicetree: update documentation for fw_cfg ARM bindings
.../ABI/testing/sysfs-firmware-qemu_fw_cfg | 240 +++++++
Documentation/devicetree/bindings/arm/fw-cfg.txt | 37 +-
drivers/firmware/Kconfig | 19 +
drivers/firmware/Makefile | 1 +
drivers/firmware/qemu_fw_cfg.c | 714 +++++++++++++++++++++
lib/kobject.c | 1 +
6 files changed, 977 insertions(+), 35 deletions(-)
create mode 100644 Documentation/ABI/testing/sysfs-firmware-qemu_fw_cfg
create mode 100644 drivers/firmware/qemu_fw_cfg.c
--
2.4.3
From: Gabriel Somlo <[email protected]>
Make fw_cfg entries of type "file" available via sysfs. Entries
are listed under /sys/firmware/qemu_fw_cfg/by_key, in folders
named after each entry's selector key. Filename, selector value,
and size read-only attributes are included for each entry. Also,
a "raw" attribute allows retrieval of the full binary content of
each entry.
This patch also provides a documentation file outlining the
guest-side "hardware" interface exposed by the QEMU fw_cfg device.
The fw_cfg device can be instantiated automatically from ACPI or
the Device Tree, or manually by using a kernel module (or command
line) parameter, with a syntax outlined in the documentation file.
Signed-off-by: Gabriel Somlo <[email protected]>
---
.../ABI/testing/sysfs-firmware-qemu_fw_cfg | 198 +++++++
drivers/firmware/Kconfig | 19 +
drivers/firmware/Makefile | 1 +
drivers/firmware/qemu_fw_cfg.c | 611 +++++++++++++++++++++
4 files changed, 829 insertions(+)
create mode 100644 Documentation/ABI/testing/sysfs-firmware-qemu_fw_cfg
create mode 100644 drivers/firmware/qemu_fw_cfg.c
diff --git a/Documentation/ABI/testing/sysfs-firmware-qemu_fw_cfg b/Documentation/ABI/testing/sysfs-firmware-qemu_fw_cfg
new file mode 100644
index 0000000..b908b6d
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-firmware-qemu_fw_cfg
@@ -0,0 +1,198 @@
+What: /sys/firmware/qemu_fw_cfg/
+Date: August 2015
+Contact: Gabriel Somlo <[email protected]>
+Description:
+ Several different architectures supported by QEMU (x86, arm,
+ sun4*, ppc/mac) are provisioned with a firmware configuration
+ (fw_cfg) device, originally intended as a way for the host to
+ provide configuration data to the guest firmware. Starting
+ with QEMU v2.4, arbitrary fw_cfg file entries may be specified
+ by the user on the command line, which makes fw_cfg additionally
+ useful as an out-of-band, asynchronous mechanism for providing
+ configuration data to the guest userspace.
+
+ === Guest-side Hardware Interface ===
+
+ The fw_cfg device is available to guest VMs as a register pair
+ (control and data), accessible as either a IO ports or as MMIO
+ addresses, depending on the architecture.
+
+ --- Control Register ---
+
+ Width: 16-bit
+ Access: Write-Only
+ Endianness: LE (if IOport) or BE (if MMIO)
+
+ A write to the control register selects the index for one of
+ the firmware configuration items (or "blobs") available on the
+ fw_cfg device, which can subsequently be read from the data
+ register.
+
+ Each time the control register is written, an data offset
+ internal to the fw_cfg device will be set to zero. This data
+ offset impacts which portion of the selected fw_cfg blob is
+ accessed by reading the data register, as explained below.
+
+ --- Data Register ---
+
+ Width: 8-bit (if IOport), or 8/16/32/64-bit (if MMIO)
+ Access: Read-Only
+ Endianness: string preserving
+
+ The data register allows access to an array of bytes which
+ represent the fw_cfg blob last selected by a write to the
+ control register.
+
+ Immediately following a write to the control register, the data
+ offset will be set to zero. Each successful read access to the
+ data register will increment the data offset by the appropriate
+ access width.
+
+ Each fw_cfg blob has a maximum associated data length. Once the
+ data offset exceeds this maximum length, any subsequent reads
+ via the data register will return 0x00.
+
+ An N-byte wide read of the data register will return the next
+ available N bytes of the selected fw_cfg blob, as a substring,
+ in increasing address order, similar to memcpy(), zero-padded
+ if necessary should the maximum data length of the selected
+ item be reached, as described above.
+
+ --- Per-arch Register Details ---
+
+ -------------------------------------------------------------
+ arch access base ctrl ctrl data max.
+ mode address offset endian offset data
+ (bytes) (bytes)
+ -------------------------------------------------------------
+ x86 IOport 0x510 0 LE 1 1
+ arm MMIO 0x9020000 8 BE 0 8
+ sun4u IOport 0x510 0 LE 1 1
+ sun4m MMIO 0xd00000510 0 BE 2 1
+ ppc/mac MMIO 0xf0000510 0 BE 2 1
+ -------------------------------------------------------------
+
+ NOTE 1. On platforms where the fw_cfg registers are exposed as
+ IO ports, the data port number will always be one greater than
+ the port number of the control register. I.e., the two ports
+ are overlapping, and can not be mapped separately.
+
+ NOTE 2. QEMU publishes the base and size of the register set
+ in ACPI (as _HID "QEMU0002", on x86 and select aarch64 subsets)
+ and in the Device Tree (as compatible = "qemu,fw-cfg-mmio", on
+ arm guests).
+
+ NOTE 3. On architectures where automatic detection of fw_cfg
+ "hardware" (via ACPI or DT) is not supported, the guest side
+ kernel driver allows configuration using a command line
+ parameter, with the following syntax:
+
+ [fw_cfg.]ioport=<size>@<base>[:<ctrl_off>:<data_off>]
+ or
+ [fw_cfg.]mmio=<size>@<base>[:<ctrl_off>:<data_off>]
+
+ where:
+ <size> : size of ioport or mmio range
+ <base> : physical base address of ioport or mmio range
+ and, optionally:
+ <ctrl_off> : offset of control register
+ <data_off> : offset of data register
+
+ Since neither ACPI nor DT provide specific details on register
+ offsets within the overall specified register set range, using
+ <ctrl_off> and <data_off> allows the arm-specific default MMIO
+ offset values (8 and 0, respectively) to be overridden for e.g.
+ sun4m and ppc/mac, where the ofsets should be 0 and 2,
+ respectively. Using ppc/mac as an example:
+
+ fw_cfg.mmio=3@0xf0000510:0:2
+
+ === Firmware Configuration Items of Interest ===
+
+ Originally, the index key, size, and formatting of blobs in
+ fw_cfg was hard coded by mutual agreement between QEMU on the
+ host side, and the guest-side firmware. Later on, a file
+ transfer interface was added: by reading a special blob, the
+ fw_cfg consumer can retrieve a list of records containing the
+ name, selector key, and size of further fw_cfg blobs made
+ available by the host. Below we describe three fw_cfg blobs
+ of interest to the sysfs driver.
+
+ --- Signature (Key 0x0000, FW_CFG_SIGNATURE) ---
+
+ The presence of the fw_cfg device can be verified by selecting
+ the signature blob by writing 0x0000 to the control register,
+ and reading four bytes from the data register. If the fw_cfg
+ device is present, the four bytes read will match the ASCII
+ characters "QEMU".
+
+ --- Revision (Key 0x0001, FW_CFG_ID) ---
+
+ A 32-bit little-endian unsigned integer, this item is used as
+ an interface revision number.
+
+ --- File Directory (Key 0x0019, FW_CFG_FILE_DIR) ---
+
+ Any fw_cfg blobs stored at key 0x0020 FW_CFG_FILE_FIRST() or
+ higher will have an associated entry in this "directory" blob,
+ which facilitates the discovery of available items by software
+ (e.g. BIOS) running on the guest. The format of the directory
+ blob is shown below.
+
+ NOTE: All integers are stored in big-endian format!
+
+ /* the entire file directory "blob" */
+ struct FWCfgFiles {
+ u32 count; /* total number of entries */
+ struct FWCfgFile f[]; /* entry array, see below */
+ };
+
+ /* an individual directory entry, 64 bytes total */
+ struct FWCfgFile {
+ u32 size; /* size of referenced blob */
+ u16 select; /* selector key for referenced blob */
+ u16 reserved;
+ char name[56]; /* blob name, nul-terminated ASCII */
+ };
+
+ === SysFS fw_cfg Interface ===
+
+ The fw_cfg sysfs interface described in this document is only
+ intended to display discoverable blobs (i.e., those registered
+ with the file directory), as there is no way to determine the
+ presence or size of "legacy" blobs (with selector keys between
+ 0x0002 and 0x0018) programmatically.
+
+ All fw_cfg information is shown under:
+
+ /sys/firmware/qemu_fw_cfg/
+
+ The only legacy blob displayed is the fw_cfg device revision:
+
+ /sys/firmware/qemu_fw_cfg/rev
+
+ --- Discoverable fw_cfg blobs by selector key ---
+
+ All discoverable blobs listed in the fw_cfg file directory are
+ displayed as entries named after their unique selector key
+ value, e.g.:
+
+ /sys/firmware/qemu_fw_cfg/by_key/32
+ /sys/firmware/qemu_fw_cfg/by_key/33
+ /sys/firmware/qemu_fw_cfg/by_key/34
+ ...
+
+ Each such fw_cfg sysfs entry has the following values exported
+ as attributes:
+
+ name : The 56-byte nul-terminated ASCII string used as the
+ blob's 'file name' in the fw_cfg directory.
+ size : The length of the blob, as given in the fw_cfg
+ directory.
+ key : The value of the blob's selector key as given in the
+ fw_cfg directory. This value is the same as used in
+ the parent directory name.
+ raw : The raw bytes of the blob, obtained by selecting the
+ entry via the control register, and reading a number
+ of bytes equal to the blob size from the data
+ register.
diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
index cf478fe..3cf920a 100644
--- a/drivers/firmware/Kconfig
+++ b/drivers/firmware/Kconfig
@@ -161,6 +161,25 @@ config RASPBERRYPI_FIRMWARE
This option enables support for communicating with the firmware on the
Raspberry Pi.
+config FW_CFG_SYSFS
+ tristate "QEMU fw_cfg device support in sysfs"
+ depends on SYSFS
+ default n
+ help
+ Say Y or M here to enable the exporting of the QEMU firmware
+ configuration (fw_cfg) file entries via sysfs. Entries are
+ found under /sys/firmware/fw_cfg when this option is enabled
+ and loaded.
+
+config FW_CFG_SYSFS_CMDLINE
+ bool "QEMU fw_cfg device parameter parsing"
+ depends on FW_CFG_SYSFS
+ help
+ Allow the qemu_fw_cfg device to be initialized via the kernel
+ command line or using a module parameter.
+ WARNING: Using incorrect parameters (base address in particular)
+ may crash your system.
+
config QCOM_SCM
bool
depends on ARM || ARM64
diff --git a/drivers/firmware/Makefile b/drivers/firmware/Makefile
index 48dd417..474bada 100644
--- a/drivers/firmware/Makefile
+++ b/drivers/firmware/Makefile
@@ -14,6 +14,7 @@ obj-$(CONFIG_ISCSI_IBFT_FIND) += iscsi_ibft_find.o
obj-$(CONFIG_ISCSI_IBFT) += iscsi_ibft.o
obj-$(CONFIG_FIRMWARE_MEMMAP) += memmap.o
obj-$(CONFIG_RASPBERRYPI_FIRMWARE) += raspberrypi.o
+obj-$(CONFIG_FW_CFG_SYSFS) += qemu_fw_cfg.o
obj-$(CONFIG_QCOM_SCM) += qcom_scm.o
obj-$(CONFIG_QCOM_SCM_64) += qcom_scm-64.o
obj-$(CONFIG_QCOM_SCM_32) += qcom_scm-32.o
diff --git a/drivers/firmware/qemu_fw_cfg.c b/drivers/firmware/qemu_fw_cfg.c
new file mode 100644
index 0000000..618304a
--- /dev/null
+++ b/drivers/firmware/qemu_fw_cfg.c
@@ -0,0 +1,611 @@
+/*
+ * drivers/firmware/qemu_fw_cfg.c
+ *
+ * Copyright 2015 Carnegie Mellon University
+ *
+ * Expose entries from QEMU's firmware configuration (fw_cfg) device in
+ * sysfs (read-only, under "/sys/firmware/qemu_fw_cfg/...").
+ *
+ * The fw_cfg device may be instantiated via either an ACPI node (on x86
+ * and select subsets of aarch64), a Device Tree node (on arm), or using
+ * a kernel module (or command line) parameter with the following syntax:
+ *
+ * [fw_cfg.]ioport=<size>@<base>[:<ctrl_off>:<data_off>]
+ * or
+ * [fw_cfg.]mmio=<size>@<base>[:<ctrl_off>:<data_off>]
+ *
+ * where:
+ * <size> := size of ioport or mmio range
+ * <base> := physical base address of ioport or mmio range
+ * <ctrl_off> := (optional) offset of control register
+ * <data_off> := (optional) offset of data register
+ *
+ * e.g.:
+ * fw_cfg.ioport=2@0x510:0:1 (the default on x86)
+ * or
+ * fw_cfg.mmio=0xA@0x9020000:8:0 (the default on arm)
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/acpi.h>
+#include <linux/slab.h>
+#include <linux/io.h>
+#include <linux/ioport.h>
+
+MODULE_AUTHOR("Gabriel L. Somlo <[email protected]>");
+MODULE_DESCRIPTION("QEMU fw_cfg sysfs support");
+MODULE_LICENSE("GPL");
+
+/* selector key values for "well-known" fw_cfg entries */
+#define FW_CFG_SIGNATURE 0x00
+#define FW_CFG_ID 0x01
+#define FW_CFG_FILE_DIR 0x19
+
+/* size in bytes of fw_cfg signature */
+#define FW_CFG_SIG_SIZE 4
+
+/* fw_cfg "file name" is up to 56 characters (including terminating nul) */
+#define FW_CFG_MAX_FILE_PATH 56
+
+/* fw_cfg file directory entry type */
+struct fw_cfg_file {
+ u32 size;
+ u16 select;
+ u16 reserved;
+ char name[FW_CFG_MAX_FILE_PATH];
+};
+
+/* fw_cfg device i/o register addresses */
+static bool fw_cfg_is_mmio;
+static phys_addr_t fw_cfg_p_base;
+static resource_size_t fw_cfg_p_size;
+static void __iomem *fw_cfg_dev_base;
+static void __iomem *fw_cfg_reg_ctrl;
+static void __iomem *fw_cfg_reg_data;
+
+/* atomic access to fw_cfg device (potentially slow i/o, so using mutex) */
+static DEFINE_MUTEX(fw_cfg_dev_lock);
+
+/* pick appropriate endianness for selector key */
+static inline u16 fw_cfg_sel_endianness(u16 key)
+{
+ return fw_cfg_is_mmio ? cpu_to_be16(key) : cpu_to_le16(key);
+}
+
+/* read chunk of given fw_cfg blob (caller responsible for sanity-check) */
+static inline void fw_cfg_read_blob(u16 key,
+ void *buf, loff_t pos, size_t count)
+{
+ mutex_lock(&fw_cfg_dev_lock);
+ iowrite16(fw_cfg_sel_endianness(key), fw_cfg_reg_ctrl);
+ while (pos-- > 0)
+ ioread8(fw_cfg_reg_data);
+ ioread8_rep(fw_cfg_reg_data, buf, count);
+ mutex_unlock(&fw_cfg_dev_lock);
+}
+
+/* clean up fw_cfg device i/o */
+static void fw_cfg_io_cleanup(void)
+{
+ if (fw_cfg_is_mmio) {
+ iounmap(fw_cfg_dev_base);
+ release_mem_region(fw_cfg_p_base, fw_cfg_p_size);
+ } else {
+ ioport_unmap(fw_cfg_dev_base);
+ release_region(fw_cfg_p_base, fw_cfg_p_size);
+ }
+}
+
+/* initialize fw_cfg device i/o from platform data */
+static int fw_cfg_do_platform_probe(struct platform_device *pdev)
+{
+ char sig[FW_CFG_SIG_SIZE];
+ struct resource *range, *ctrl, *data;
+
+ /* acquire i/o range details */
+ fw_cfg_is_mmio = false;
+ range = platform_get_resource(pdev, IORESOURCE_IO, 0);
+ if (!range) {
+ fw_cfg_is_mmio = true;
+ range = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!range)
+ return -EINVAL;
+ }
+ fw_cfg_p_base = range->start;
+ fw_cfg_p_size = resource_size(range);
+
+ if (fw_cfg_is_mmio) {
+ if (!request_mem_region(fw_cfg_p_base,
+ fw_cfg_p_size, "fw_cfg_mem"))
+ return -EBUSY;
+ fw_cfg_dev_base = ioremap(fw_cfg_p_base, fw_cfg_p_size);
+ if (!fw_cfg_dev_base) {
+ release_mem_region(fw_cfg_p_base, fw_cfg_p_size);
+ return -EFAULT;
+ }
+ /* set register addresses (using arm/mmio offsets) */
+ fw_cfg_reg_ctrl = fw_cfg_dev_base + 0x08;
+ fw_cfg_reg_data = fw_cfg_dev_base + 0x00;
+ } else {
+ if (!request_region(fw_cfg_p_base,
+ fw_cfg_p_size, "fw_cfg_io"))
+ return -EBUSY;
+ fw_cfg_dev_base = ioport_map(fw_cfg_p_base, fw_cfg_p_size);
+ if (!fw_cfg_dev_base) {
+ release_region(fw_cfg_p_base, fw_cfg_p_size);
+ return -EFAULT;
+ }
+ /* set register addresses (using pc/i386/ioport offsets) */
+ fw_cfg_reg_ctrl = fw_cfg_dev_base + 0x00;
+ fw_cfg_reg_data = fw_cfg_dev_base + 0x01;
+ }
+
+ /* were custom register offsets provided (e.g. on the command line)? */
+ ctrl = platform_get_resource_byname(pdev, IORESOURCE_REG, "ctrl");
+ data = platform_get_resource_byname(pdev, IORESOURCE_REG, "data");
+ if (ctrl && data) {
+ fw_cfg_reg_ctrl = fw_cfg_dev_base + ctrl->start;
+ fw_cfg_reg_data = fw_cfg_dev_base + data->start;
+ }
+
+ /* verify fw_cfg device signature */
+ fw_cfg_read_blob(FW_CFG_SIGNATURE, sig, 0, FW_CFG_SIG_SIZE);
+ if (memcmp(sig, "QEMU", FW_CFG_SIG_SIZE) != 0) {
+ fw_cfg_io_cleanup();
+ return -ENODEV;
+ }
+
+ return 0;
+}
+
+/* fw_cfg revision attribute, in /sys/firmware/qemu_fw_cfg top-level dir. */
+static u32 fw_cfg_rev;
+
+static ssize_t fw_cfg_showrev(struct kobject *k, struct attribute *a, char *buf)
+{
+ return sprintf(buf, "%u\n", fw_cfg_rev);
+}
+
+static const struct {
+ struct attribute attr;
+ ssize_t (*show)(struct kobject *k, struct attribute *a, char *buf);
+} fw_cfg_rev_attr = {
+ .attr = { .name = "rev", .mode = S_IRUSR },
+ .show = fw_cfg_showrev,
+};
+
+/* fw_cfg_sysfs_entry type */
+struct fw_cfg_sysfs_entry {
+ struct kobject kobj;
+ struct fw_cfg_file f;
+ struct list_head list;
+};
+
+/* get fw_cfg_sysfs_entry from kobject member */
+static inline struct fw_cfg_sysfs_entry *to_entry(struct kobject *kobj)
+{
+ return container_of(kobj, struct fw_cfg_sysfs_entry, kobj);
+}
+
+/* fw_cfg_sysfs_attribute type */
+struct fw_cfg_sysfs_attribute {
+ struct attribute attr;
+ ssize_t (*show)(struct fw_cfg_sysfs_entry *entry, char *buf);
+};
+
+/* get fw_cfg_sysfs_attribute from attribute member */
+static inline struct fw_cfg_sysfs_attribute *to_attr(struct attribute *attr)
+{
+ return container_of(attr, struct fw_cfg_sysfs_attribute, attr);
+}
+
+/* global cache of fw_cfg_sysfs_entry objects */
+static LIST_HEAD(fw_cfg_entry_cache);
+
+/* kobjects removed lazily by kernel, mutual exclusion needed */
+static DEFINE_SPINLOCK(fw_cfg_cache_lock);
+
+static inline void fw_cfg_sysfs_cache_enlist(struct fw_cfg_sysfs_entry *entry)
+{
+ spin_lock(&fw_cfg_cache_lock);
+ list_add_tail(&entry->list, &fw_cfg_entry_cache);
+ spin_unlock(&fw_cfg_cache_lock);
+}
+
+static inline void fw_cfg_sysfs_cache_delist(struct fw_cfg_sysfs_entry *entry)
+{
+ spin_lock(&fw_cfg_cache_lock);
+ list_del(&entry->list);
+ spin_unlock(&fw_cfg_cache_lock);
+}
+
+static void fw_cfg_sysfs_cache_cleanup(void)
+{
+ struct fw_cfg_sysfs_entry *entry, *next;
+
+ list_for_each_entry_safe(entry, next, &fw_cfg_entry_cache, list) {
+ /* will end up invoking fw_cfg_sysfs_cache_delist()
+ * via each object's release() method (i.e. destructor)
+ */
+ kobject_put(&entry->kobj);
+ }
+}
+
+/* default_attrs: per-entry attributes and show methods */
+
+#define FW_CFG_SYSFS_ATTR(_attr) \
+struct fw_cfg_sysfs_attribute fw_cfg_sysfs_attr_##_attr = { \
+ .attr = { .name = __stringify(_attr), .mode = S_IRUSR }, \
+ .show = fw_cfg_sysfs_show_##_attr, \
+}
+
+static ssize_t fw_cfg_sysfs_show_size(struct fw_cfg_sysfs_entry *e, char *buf)
+{
+ return sprintf(buf, "%u\n", e->f.size);
+}
+
+static ssize_t fw_cfg_sysfs_show_key(struct fw_cfg_sysfs_entry *e, char *buf)
+{
+ return sprintf(buf, "%u\n", e->f.select);
+}
+
+static ssize_t fw_cfg_sysfs_show_name(struct fw_cfg_sysfs_entry *e, char *buf)
+{
+ return sprintf(buf, "%s\n", e->f.name);
+}
+
+static FW_CFG_SYSFS_ATTR(size);
+static FW_CFG_SYSFS_ATTR(key);
+static FW_CFG_SYSFS_ATTR(name);
+
+static struct attribute *fw_cfg_sysfs_entry_attrs[] = {
+ &fw_cfg_sysfs_attr_size.attr,
+ &fw_cfg_sysfs_attr_key.attr,
+ &fw_cfg_sysfs_attr_name.attr,
+ NULL,
+};
+
+/* sysfs_ops: find fw_cfg_[entry, attribute] and call appropriate show method */
+static ssize_t fw_cfg_sysfs_attr_show(struct kobject *kobj, struct attribute *a,
+ char *buf)
+{
+ struct fw_cfg_sysfs_entry *entry = to_entry(kobj);
+ struct fw_cfg_sysfs_attribute *attr = to_attr(a);
+
+ return attr->show(entry, buf);
+}
+
+static const struct sysfs_ops fw_cfg_sysfs_attr_ops = {
+ .show = fw_cfg_sysfs_attr_show,
+};
+
+/* release: destructor, to be called via kobject_put() */
+static void fw_cfg_sysfs_release_entry(struct kobject *kobj)
+{
+ struct fw_cfg_sysfs_entry *entry = to_entry(kobj);
+
+ fw_cfg_sysfs_cache_delist(entry);
+ kfree(entry);
+}
+
+/* kobj_type: ties together all properties required to register an entry */
+static struct kobj_type fw_cfg_sysfs_entry_ktype = {
+ .default_attrs = fw_cfg_sysfs_entry_attrs,
+ .sysfs_ops = &fw_cfg_sysfs_attr_ops,
+ .release = fw_cfg_sysfs_release_entry,
+};
+
+/* raw-read method and attribute */
+static ssize_t fw_cfg_sysfs_read_raw(struct file *filp, struct kobject *kobj,
+ struct bin_attribute *bin_attr,
+ char *buf, loff_t pos, size_t count)
+{
+ struct fw_cfg_sysfs_entry *entry = to_entry(kobj);
+
+ if (pos > entry->f.size)
+ return -EINVAL;
+
+ if (count > entry->f.size - pos)
+ count = entry->f.size - pos;
+
+ fw_cfg_read_blob(entry->f.select, buf, pos, count);
+ return count;
+}
+
+static struct bin_attribute fw_cfg_sysfs_attr_raw = {
+ .attr = { .name = "raw", .mode = S_IRUSR },
+ .read = fw_cfg_sysfs_read_raw,
+};
+
+/* kobjects representing top-level and by_key folders */
+static struct kobject *fw_cfg_top_ko;
+static struct kobject *fw_cfg_sel_ko;
+
+/* register an individual fw_cfg file */
+static int fw_cfg_register_file(const struct fw_cfg_file *f)
+{
+ int err;
+ struct fw_cfg_sysfs_entry *entry;
+
+ /* allocate new entry */
+ entry = kzalloc(sizeof(*entry), GFP_KERNEL);
+ if (!entry)
+ return -ENOMEM;
+
+ /* set file entry information */
+ memcpy(&entry->f, f, sizeof(struct fw_cfg_file));
+
+ /* register entry under "/sys/firmware/qemu_fw_cfg/by_key/" */
+ err = kobject_init_and_add(&entry->kobj, &fw_cfg_sysfs_entry_ktype,
+ fw_cfg_sel_ko, "%d", entry->f.select);
+ if (err)
+ goto err_register;
+
+ /* add raw binary content access */
+ err = sysfs_create_bin_file(&entry->kobj, &fw_cfg_sysfs_attr_raw);
+ if (err)
+ goto err_add_raw;
+
+ /* success, add entry to global cache */
+ fw_cfg_sysfs_cache_enlist(entry);
+ return 0;
+
+err_add_raw:
+ kobject_del(&entry->kobj);
+err_register:
+ kfree(entry);
+ return err;
+}
+
+/* iterate over all fw_cfg directory entries, registering each one */
+static int fw_cfg_register_dir_entries(void)
+{
+ int ret = 0;
+ u32 count, i;
+ struct fw_cfg_file *dir;
+ size_t dir_size;
+
+ fw_cfg_read_blob(FW_CFG_FILE_DIR, &count, 0, sizeof(count));
+ count = be32_to_cpu(count);
+ dir_size = count * sizeof(struct fw_cfg_file);
+
+ dir = kmalloc(dir_size, GFP_KERNEL);
+ if (!dir)
+ return -ENOMEM;
+
+ fw_cfg_read_blob(FW_CFG_FILE_DIR, dir, sizeof(count), dir_size);
+
+ for (i = 0; i < count; i++) {
+ dir[i].size = be32_to_cpu(dir[i].size);
+ dir[i].select = be16_to_cpu(dir[i].select);
+ ret = fw_cfg_register_file(&dir[i]);
+ if (ret)
+ break;
+ }
+
+ kfree(dir);
+ return ret;
+}
+
+/* unregister top-level or by_key folder */
+static inline void fw_cfg_kobj_cleanup(struct kobject *kobj)
+{
+ kobject_del(kobj);
+ kobject_put(kobj);
+}
+
+static int fw_cfg_sysfs_probe(struct platform_device *pdev)
+{
+ int err;
+
+ /* NOTE: If we supported multiple fw_cfg devices, we'd first create
+ * a subdirectory named after e.g. pdev->id, then hang per-device
+ * by_key subdirectories underneath it. However, only
+ * one fw_cfg device exist system-wide, so if one was already found
+ * earlier, we might as well stop here.
+ */
+ if (fw_cfg_sel_ko)
+ return -EBUSY;
+
+ /* create by_key subdirectory of /sys/firmware/qemu_fw_cfg/ */
+ err = -ENOMEM;
+ fw_cfg_sel_ko = kobject_create_and_add("by_key", fw_cfg_top_ko);
+ if (!fw_cfg_sel_ko)
+ goto err_sel;
+
+ /* initialize fw_cfg device i/o from platform data */
+ err = fw_cfg_do_platform_probe(pdev);
+ if (err)
+ goto err_probe;
+
+ /* get revision number, add matching top-level attribute */
+ fw_cfg_read_blob(FW_CFG_ID, &fw_cfg_rev, 0, sizeof(fw_cfg_rev));
+ fw_cfg_rev = le32_to_cpu(fw_cfg_rev);
+ err = sysfs_create_file(fw_cfg_top_ko, &fw_cfg_rev_attr.attr);
+ if (err)
+ goto err_rev;
+
+ /* process fw_cfg file directory entry, registering each file */
+ err = fw_cfg_register_dir_entries();
+ if (err)
+ goto err_dir;
+
+ /* success */
+ pr_debug("fw_cfg: loaded.\n");
+ return 0;
+
+err_dir:
+ fw_cfg_sysfs_cache_cleanup();
+ sysfs_remove_file(fw_cfg_top_ko, &fw_cfg_rev_attr.attr);
+err_rev:
+ fw_cfg_io_cleanup();
+err_probe:
+ fw_cfg_kobj_cleanup(fw_cfg_sel_ko);
+err_sel:
+ return err;
+}
+
+static int fw_cfg_sysfs_remove(struct platform_device *pdev)
+{
+ pr_debug("fw_cfg: unloading.\n");
+ fw_cfg_sysfs_cache_cleanup();
+ fw_cfg_kobj_cleanup(fw_cfg_sel_ko);
+ fw_cfg_io_cleanup();
+ return 0;
+}
+
+static const struct of_device_id fw_cfg_sysfs_mmio_match[] = {
+ { .compatible = "qemu,fw-cfg-mmio", },
+ {},
+};
+MODULE_DEVICE_TABLE(of, fw_cfg_sysfs_mmio_match);
+
+#ifdef CONFIG_ACPI
+static const struct acpi_device_id fw_cfg_sysfs_acpi_match[] = {
+ { "QEMU0002", },
+ {},
+};
+MODULE_DEVICE_TABLE(acpi, fw_cfg_sysfs_acpi_match);
+#endif
+
+static struct platform_driver fw_cfg_sysfs_driver = {
+ .probe = fw_cfg_sysfs_probe,
+ .remove = fw_cfg_sysfs_remove,
+ .driver = {
+ .name = "fw_cfg",
+ .of_match_table = fw_cfg_sysfs_mmio_match,
+ .acpi_match_table = ACPI_PTR(fw_cfg_sysfs_acpi_match),
+ },
+};
+
+#ifdef CONFIG_FW_CFG_SYSFS_CMDLINE
+
+static struct platform_device *fw_cfg_cmdline_dev;
+
+static int fw_cfg_cmdline_set(const char *arg, const struct kernel_param *kp)
+{
+ struct resource res[3] = {};
+ char *str;
+ phys_addr_t base;
+ resource_size_t size, ctrl_off, data_off;
+ int processed, consumed = 0;
+
+ /* only one fw_cfg device can exist system-wide, so if one
+ * was processed on the command line already, we might as
+ * well stop here.
+ */
+ if (fw_cfg_cmdline_dev) {
+ /* avoid leaking previously registered device */
+ platform_device_unregister(fw_cfg_cmdline_dev);
+ return -EINVAL;
+ }
+
+ /* consume "<size>" portion of command line argument */
+ size = memparse(arg, &str);
+
+ /* get "@<base>[:<ctrl_off>:<data_off>]" chunks */
+ processed = sscanf(str, "@%lli%n:%lli:%lli%n",
+ &base, &consumed,
+ &ctrl_off, &data_off, &consumed);
+
+ /* sscanf() must process precisely 1 or 3 chunks:
+ * <base> is mandatory, optionally followed by <ctrl_off>
+ * and <data_off>;
+ * there must be no extra characters after the last chunk,
+ * so str[consumed] must be '\0'.
+ */
+ if (str[consumed] ||
+ (processed != 1 && processed != 3))
+ return -EINVAL;
+
+ res[0].start = base;
+ res[0].end = base + size - 1;
+ res[0].flags = !strcmp(kp->name, "mmio") ? IORESOURCE_MEM :
+ IORESOURCE_IO;
+
+ /* insert register offsets, if provided */
+ if (processed > 1) {
+ res[1].name = "ctrl";
+ res[1].start = ctrl_off;
+ res[1].flags = IORESOURCE_REG;
+ res[2].name = "data";
+ res[2].start = data_off;
+ res[2].flags = IORESOURCE_REG;
+ }
+
+ /* "processed" happens to nicely match the number of resources
+ * we need to pass in to this platform device.
+ */
+ fw_cfg_cmdline_dev = platform_device_register_simple("fw_cfg",
+ PLATFORM_DEVID_NONE, res, processed);
+ if (IS_ERR(fw_cfg_cmdline_dev))
+ return PTR_ERR(fw_cfg_cmdline_dev);
+
+ return 0;
+}
+
+static int fw_cfg_cmdline_get(char *buf, const struct kernel_param *kp)
+{
+ /* stay silent if device was not configured via the command
+ * line, or if the parameter name (ioport/mmio) doesn't match
+ * the device setting
+ */
+ if (!fw_cfg_cmdline_dev ||
+ (!strcmp(kp->name, "mmio") ^
+ (fw_cfg_cmdline_dev->resource[0].flags == IORESOURCE_MEM)))
+ return 0;
+
+ switch (fw_cfg_cmdline_dev->num_resources) {
+ case 1:
+ return snprintf(buf, PAGE_SIZE, "0x%llx@0x%llx",
+ resource_size(&fw_cfg_cmdline_dev->resource[0]),
+ fw_cfg_cmdline_dev->resource[0].start);
+ case 3:
+ return snprintf(buf, PAGE_SIZE, "0x%llx@0x%llx:%llu:%llu",
+ resource_size(&fw_cfg_cmdline_dev->resource[0]),
+ fw_cfg_cmdline_dev->resource[0].start,
+ fw_cfg_cmdline_dev->resource[1].start,
+ fw_cfg_cmdline_dev->resource[2].start);
+ }
+
+ /* Should never get here */
+ WARN(1, "Unexpected number of resources: %d\n",
+ fw_cfg_cmdline_dev->num_resources);
+ return 0;
+}
+
+static const struct kernel_param_ops fw_cfg_cmdline_param_ops = {
+ .set = fw_cfg_cmdline_set,
+ .get = fw_cfg_cmdline_get,
+};
+
+device_param_cb(ioport, &fw_cfg_cmdline_param_ops, NULL, S_IRUSR);
+device_param_cb(mmio, &fw_cfg_cmdline_param_ops, NULL, S_IRUSR);
+
+#endif /* CONFIG_FW_CFG_SYSFS_CMDLINE */
+
+static int __init fw_cfg_sysfs_init(void)
+{
+ /* create /sys/firmware/qemu_fw_cfg/ top level directory */
+ fw_cfg_top_ko = kobject_create_and_add("qemu_fw_cfg", firmware_kobj);
+ if (!fw_cfg_top_ko)
+ return -ENOMEM;
+
+ return platform_driver_register(&fw_cfg_sysfs_driver);
+}
+
+static void __exit fw_cfg_sysfs_exit(void)
+{
+ platform_driver_unregister(&fw_cfg_sysfs_driver);
+
+#ifdef CONFIG_FW_CFG_SYSFS_CMDLINE
+ platform_device_unregister(fw_cfg_cmdline_dev);
+#endif
+
+ /* clean up /sys/firmware/qemu_fw_cfg/ */
+ fw_cfg_kobj_cleanup(fw_cfg_top_ko);
+}
+
+module_init(fw_cfg_sysfs_init);
+module_exit(fw_cfg_sysfs_exit);
--
2.4.3
From: Gabriel Somlo <[email protected]>
Signed-off-by: Gabriel Somlo <[email protected]>
---
lib/kobject.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/lib/kobject.c b/lib/kobject.c
index 7cbccd2..90d1be6 100644
--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -861,6 +861,7 @@ struct kobject *kset_find_obj(struct kset *kset, const char *name)
spin_unlock(&kset->list_lock);
return ret;
}
+EXPORT_SYMBOL(kset_find_obj);
static void kset_release(struct kobject *kobj)
{
--
2.4.3
From: Gabriel Somlo <[email protected]>
Each fw_cfg entry of type "file" has an associated 56-char,
nul-terminated ASCII string which represents its name. While
the fw_cfg device doesn't itself impose any specific naming
convention, QEMU developers have traditionally used path name
semantics (i.e. "etc/acpi/rsdp") to descriptively name the
various fw_cfg "blobs" passed into the guest.
This patch attempts, on a best effort basis, to create a
directory hierarchy representing the content of fw_cfg file
names, under /sys/firmware/qemu_fw_cfg/by_name.
Upon successful creation of all directories representing the
"dirname" portion of a fw_cfg file, a symlink will be created
to represent the "basename", pointing at the appropriate
/sys/firmware/qemu_fw_cfg/by_key entry. If a file name is not
suitable for this procedure (e.g., if its basename or dirname
components collide with an already existing dirname component
or basename, respectively) the corresponding fw_cfg blob is
skipped and will remain available in sysfs only by its selector
key value.
Signed-off-by: Gabriel Somlo <[email protected]>
Cc: Andy Lutomirski <[email protected]>
---
.../ABI/testing/sysfs-firmware-qemu_fw_cfg | 42 ++++++++
drivers/firmware/qemu_fw_cfg.c | 109 ++++++++++++++++++++-
2 files changed, 148 insertions(+), 3 deletions(-)
diff --git a/Documentation/ABI/testing/sysfs-firmware-qemu_fw_cfg b/Documentation/ABI/testing/sysfs-firmware-qemu_fw_cfg
index b908b6d..a346ee0 100644
--- a/Documentation/ABI/testing/sysfs-firmware-qemu_fw_cfg
+++ b/Documentation/ABI/testing/sysfs-firmware-qemu_fw_cfg
@@ -196,3 +196,45 @@ Description:
entry via the control register, and reading a number
of bytes equal to the blob size from the data
register.
+
+ --- Listing fw_cfg blobs by file name ---
+
+ While the fw_cfg device does not impose any specific naming
+ convention on the blobs registered in the file directory,
+ QEMU developers have traditionally used path name semantics
+ to give each blob a descriptive name. For example:
+
+ "bootorder"
+ "genroms/kvmvapic.bin"
+ "etc/e820"
+ "etc/boot-fail-wait"
+ "etc/system-states"
+ "etc/table-loader"
+ "etc/acpi/rsdp"
+ "etc/acpi/tables"
+ "etc/smbios/smbios-tables"
+ "etc/smbios/smbios-anchor"
+ ...
+
+ In addition to the listing by unique selector key described
+ above, the fw_cfg sysfs driver also attempts to build a tree
+ of directories matching the path name components of fw_cfg
+ blob names, ending in symlinks to the by_key entry for each
+ "basename", as illustrated below (assume current directory is
+ /sys/firmware):
+
+ qemu_fw_cfg/by_name/bootorder -> ../by_key/38
+ qemu_fw_cfg/by_name/etc/e820 -> ../../by_key/35
+ qemu_fw_cfg/by_name/etc/acpi/rsdp -> ../../../by_key/41
+ ...
+
+ Construction of the directory tree and symlinks is done on a
+ "best-effort" basis, as there is no guarantee that components
+ of fw_cfg blob names are always "well behaved". I.e., there is
+ the possibility that a symlink (basename) will conflict with
+ a dirname component of another fw_cfg blob, in which case the
+ creation of the offending /sys/firmware/qemu_fw_cfg/by_name
+ entry will be skipped.
+
+ The authoritative list of entries will continue to be found
+ under the /sys/firmware/qemu_fw_cfg/by_key directory.
diff --git a/drivers/firmware/qemu_fw_cfg.c b/drivers/firmware/qemu_fw_cfg.c
index 618304a..9ac1ca7 100644
--- a/drivers/firmware/qemu_fw_cfg.c
+++ b/drivers/firmware/qemu_fw_cfg.c
@@ -318,9 +318,103 @@ static struct bin_attribute fw_cfg_sysfs_attr_raw = {
.read = fw_cfg_sysfs_read_raw,
};
-/* kobjects representing top-level and by_key folders */
+/*
+ * Create a kset subdirectory matching each '/' delimited dirname token
+ * in 'name', starting with sysfs kset/folder 'dir'; At the end, create
+ * a symlink directed at the given 'target'.
+ * NOTE: We do this on a best-effort basis, since 'name' is not guaranteed
+ * to be a well-behaved path name. Whenever a symlink vs. kset directory
+ * name collision occurs, the kernel will issue big scary warnings while
+ * refusing to add the offending link or directory. We follow up with our
+ * own, slightly less scary error messages explaining the situation :)
+ */
+static int fw_cfg_build_symlink(struct kset *dir,
+ struct kobject *target, const char *name)
+{
+ int ret;
+ struct kset *subdir;
+ struct kobject *ko;
+ char *name_copy, *p, *tok;
+
+ if (!dir || !target || !name || !*name)
+ return -EINVAL;
+
+ /* clone a copy of name for parsing */
+ name_copy = p = kstrdup(name, GFP_KERNEL);
+ if (!name_copy)
+ return -ENOMEM;
+
+ /* create folders for each dirname token, then symlink for basename */
+ while ((tok = strsep(&p, "/")) && *tok) {
+
+ /* last (basename) token? If so, add symlink here */
+ if (!p || !*p) {
+ ret = sysfs_create_link(&dir->kobj, target, tok);
+ break;
+ }
+
+ /* does the current dir contain an item named after tok ? */
+ ko = kset_find_obj(dir, tok);
+ if (ko) {
+ /* drop reference added by kset_find_obj */
+ kobject_put(ko);
+
+ /* ko MUST be a kset - we're about to use it as one ! */
+ if (ko->ktype != dir->kobj.ktype) {
+ ret = -EINVAL;
+ break;
+ }
+
+ /* descend into already existing subdirectory */
+ dir = to_kset(ko);
+ } else {
+ /* create new subdirectory kset */
+ subdir = kzalloc(sizeof(struct kset), GFP_KERNEL);
+ if (!subdir) {
+ ret = -ENOMEM;
+ break;
+ }
+ subdir->kobj.kset = dir;
+ subdir->kobj.ktype = dir->kobj.ktype;
+ ret = kobject_set_name(&subdir->kobj, "%s", tok);
+ if (ret) {
+ kfree(subdir);
+ break;
+ }
+ ret = kset_register(subdir);
+ if (ret) {
+ kfree(subdir);
+ break;
+ }
+
+ /* descend into newly created subdirectory */
+ dir = subdir;
+ }
+ }
+
+ /* we're done with cloned copy of name */
+ kfree(name_copy);
+ return ret;
+}
+
+/* recursively unregister fw_cfg/by_name/ kset directory tree */
+static void fw_cfg_kset_unregister_recursive(struct kset *kset)
+{
+ struct kobject *k, *next;
+
+ list_for_each_entry_safe(k, next, &kset->list, entry)
+ /* all set members are ksets too, but check just in case... */
+ if (k->ktype == kset->kobj.ktype)
+ fw_cfg_kset_unregister_recursive(to_kset(k));
+
+ /* symlinks are cleanly and automatically removed with the directory */
+ kset_unregister(kset);
+}
+
+/* kobjects & kset representing top-level, by_key, and by_name folders */
static struct kobject *fw_cfg_top_ko;
static struct kobject *fw_cfg_sel_ko;
+static struct kset *fw_cfg_fname_kset;
/* register an individual fw_cfg file */
static int fw_cfg_register_file(const struct fw_cfg_file *f)
@@ -347,6 +441,9 @@ static int fw_cfg_register_file(const struct fw_cfg_file *f)
if (err)
goto err_add_raw;
+ /* try adding "/sys/firmware/qemu_fw_cfg/by_name/" symlink */
+ fw_cfg_build_symlink(fw_cfg_fname_kset, &entry->kobj, entry->f.name);
+
/* success, add entry to global cache */
fw_cfg_sysfs_cache_enlist(entry);
return 0;
@@ -401,18 +498,21 @@ static int fw_cfg_sysfs_probe(struct platform_device *pdev)
/* NOTE: If we supported multiple fw_cfg devices, we'd first create
* a subdirectory named after e.g. pdev->id, then hang per-device
- * by_key subdirectories underneath it. However, only
+ * by_key (and by_name) subdirectories underneath it. However, only
* one fw_cfg device exist system-wide, so if one was already found
* earlier, we might as well stop here.
*/
if (fw_cfg_sel_ko)
return -EBUSY;
- /* create by_key subdirectory of /sys/firmware/qemu_fw_cfg/ */
+ /* create by_key and by_name subdirs of /sys/firmware/qemu_fw_cfg/ */
err = -ENOMEM;
fw_cfg_sel_ko = kobject_create_and_add("by_key", fw_cfg_top_ko);
if (!fw_cfg_sel_ko)
goto err_sel;
+ fw_cfg_fname_kset = kset_create_and_add("by_name", NULL, fw_cfg_top_ko);
+ if (!fw_cfg_fname_kset)
+ goto err_name;
/* initialize fw_cfg device i/o from platform data */
err = fw_cfg_do_platform_probe(pdev);
@@ -441,6 +541,8 @@ err_dir:
err_rev:
fw_cfg_io_cleanup();
err_probe:
+ fw_cfg_kset_unregister_recursive(fw_cfg_fname_kset);
+err_name:
fw_cfg_kobj_cleanup(fw_cfg_sel_ko);
err_sel:
return err;
@@ -450,6 +552,7 @@ static int fw_cfg_sysfs_remove(struct platform_device *pdev)
{
pr_debug("fw_cfg: unloading.\n");
fw_cfg_sysfs_cache_cleanup();
+ fw_cfg_kset_unregister_recursive(fw_cfg_fname_kset);
fw_cfg_kobj_cleanup(fw_cfg_sel_ko);
fw_cfg_io_cleanup();
return 0;
--
2.4.3
From: Gabriel Somlo <[email protected]>
Remove redundant details from
Documentation/devicetree/bindings/arm/fw-cfg.txt,
and replace them with a pointer to the more comprehensive
fw_cfg documentation privided by
Documentation/ABI/testing/sysfs-firmware-qemu_fw_cfg,
leaving the specific ARM DTB node description in place.
Signed-off-by: Gabriel Somlo <[email protected]>
Cc: Laszlo Ersek <[email protected]>
---
Documentation/devicetree/bindings/arm/fw-cfg.txt | 37 ++----------------------
1 file changed, 2 insertions(+), 35 deletions(-)
diff --git a/Documentation/devicetree/bindings/arm/fw-cfg.txt b/Documentation/devicetree/bindings/arm/fw-cfg.txt
index 953fb64..7aeb48a 100644
--- a/Documentation/devicetree/bindings/arm/fw-cfg.txt
+++ b/Documentation/devicetree/bindings/arm/fw-cfg.txt
@@ -11,43 +11,10 @@ QEMU exposes the control and data register to ARM guests as memory mapped
registers; their location is communicated to the guest's UEFI firmware in the
DTB that QEMU places at the bottom of the guest's DRAM.
-The guest writes a selector value (a key) to the selector register, and then
-can read the corresponding data (produced by QEMU) via the data register. If
-the selected entry is writable, the guest can rewrite it through the data
-register.
-The selector register takes keys in big endian byte order.
+For a comprehensive description of the behavior of fw_cfg, please see
+Documentation/ABI/testing/sysfs-firmware-qemu_fw_cfg.
-The data register allows accesses with 8, 16, 32 and 64-bit width (only at
-offset 0 of the register). Accesses larger than a byte are interpreted as
-arrays, bundled together only for better performance. The bytes constituting
-such a word, in increasing address order, correspond to the bytes that would
-have been transferred by byte-wide accesses in chronological order.
-
-The interface allows guest firmware to download various parameters and blobs
-that affect how the firmware works and what tables it installs for the guest
-OS. For example, boot order of devices, ACPI tables, SMBIOS tables, kernel and
-initrd images for direct kernel booting, virtual machine UUID, SMP information,
-virtual NUMA topology, and so on.
-
-The authoritative registry of the valid selector values and their meanings is
-the QEMU source code; the structure of the data blobs corresponding to the
-individual key values is also defined in the QEMU source code.
-
-The presence of the registers can be verified by selecting the "signature" blob
-with key 0x0000, and reading four bytes from the data register. The returned
-signature is "QEMU".
-
-The outermost protocol (involving the write / read sequences of the control and
-data registers) is expected to be versioned, and/or described by feature bits.
-The interface revision / feature bitmap can be retrieved with key 0x0001. The
-blob to be read from the data register has size 4, and it is to be interpreted
-as a uint32_t value in little endian byte order. The current value
-(corresponding to the above outer protocol) is zero.
-
-The guest kernel is not expected to use these registers (although it is
-certainly allowed to); the device tree bindings are documented here because
-this is where device tree bindings reside in general.
Required properties:
--
2.4.3
On Fri, Nov 13, 2015 at 10:03:55PM -0500, Gabriel L. Somlo wrote:
> From: Gabriel Somlo <[email protected]>
>
> Remove redundant details from
> Documentation/devicetree/bindings/arm/fw-cfg.txt,
> and replace them with a pointer to the more comprehensive
> fw_cfg documentation privided by
> Documentation/ABI/testing/sysfs-firmware-qemu_fw_cfg,
> leaving the specific ARM DTB node description in place.
We generally don't want DT docs to depend on other kernel documentation.
That will make separating them harder.
>
> Signed-off-by: Gabriel Somlo <[email protected]>
> Cc: Laszlo Ersek <[email protected]>
> ---
> Documentation/devicetree/bindings/arm/fw-cfg.txt | 37 ++----------------------
> 1 file changed, 2 insertions(+), 35 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/arm/fw-cfg.txt b/Documentation/devicetree/bindings/arm/fw-cfg.txt
> index 953fb64..7aeb48a 100644
> --- a/Documentation/devicetree/bindings/arm/fw-cfg.txt
> +++ b/Documentation/devicetree/bindings/arm/fw-cfg.txt
> @@ -11,43 +11,10 @@ QEMU exposes the control and data register to ARM guests as memory mapped
> registers; their location is communicated to the guest's UEFI firmware in the
> DTB that QEMU places at the bottom of the guest's DRAM.
>
> -The guest writes a selector value (a key) to the selector register, and then
> -can read the corresponding data (produced by QEMU) via the data register. If
> -the selected entry is writable, the guest can rewrite it through the data
> -register.
>
> -The selector register takes keys in big endian byte order.
> +For a comprehensive description of the behavior of fw_cfg, please see
> +Documentation/ABI/testing/sysfs-firmware-qemu_fw_cfg.
>
> -The data register allows accesses with 8, 16, 32 and 64-bit width (only at
> -offset 0 of the register). Accesses larger than a byte are interpreted as
> -arrays, bundled together only for better performance. The bytes constituting
> -such a word, in increasing address order, correspond to the bytes that would
> -have been transferred by byte-wide accesses in chronological order.
> -
> -The interface allows guest firmware to download various parameters and blobs
> -that affect how the firmware works and what tables it installs for the guest
> -OS. For example, boot order of devices, ACPI tables, SMBIOS tables, kernel and
> -initrd images for direct kernel booting, virtual machine UUID, SMP information,
> -virtual NUMA topology, and so on.
> -
> -The authoritative registry of the valid selector values and their meanings is
> -the QEMU source code; the structure of the data blobs corresponding to the
> -individual key values is also defined in the QEMU source code.
> -
> -The presence of the registers can be verified by selecting the "signature" blob
> -with key 0x0000, and reading four bytes from the data register. The returned
> -signature is "QEMU".
> -
> -The outermost protocol (involving the write / read sequences of the control and
> -data registers) is expected to be versioned, and/or described by feature bits.
> -The interface revision / feature bitmap can be retrieved with key 0x0001. The
> -blob to be read from the data register has size 4, and it is to be interpreted
> -as a uint32_t value in little endian byte order. The current value
> -(corresponding to the above outer protocol) is zero.
> -
> -The guest kernel is not expected to use these registers (although it is
> -certainly allowed to); the device tree bindings are documented here because
> -this is where device tree bindings reside in general.
>
> Required properties:
>
> --
> 2.4.3
>
>
On 15/11/2015 03:07, Rob Herring wrote:
> We generally don't want DT docs to depend on other kernel documentation.
DT docs do not contain a copy of the data sheets, either. There is no
reason to say how to use the device (and even then, only doing so
partially) in the DT docs.
Paolo
On Mon, Nov 16, 2015 at 09:38:18AM +0100, Paolo Bonzini wrote:
> On 15/11/2015 03:07, Rob Herring wrote:
> > We generally don't want DT docs to depend on other kernel documentation.
>
> DT docs do not contain a copy of the data sheets, either. There is no
> reason to say how to use the device (and even then, only doing so
> partially) in the DT docs.
I believe "Documentation/devicetree/bindings/arm/fw-cfg.txt"
was added by Laszlo (via commit 53275a61) mainly to document
the (base,size) DT node for ARM fw_cfg register set (based on
the idea that Documentation/devicetree/... is the authoritative
place to park DT node information like that.
The additional bits about how fw_cfg works were added for context,
since at the time the kernel itself didn't have anything else to
do with fw_cfg.
Since the sysfs driver I'm proposing (to allow fw_cfg data to be
viewed from userspace) works on a wider set of architectures (x86,
ARM, ppc/mac and sun4*), documentation on fw_cfg behavior belongs
in a more cross-platform location, such as
Documentation/ABI/testing/sysfs-firmware-qemu_fw_cfg.
So Documentation/devicetree/bindings/arm/fw-cfg.txt should probably
be limited to specifying the DT node details for ARM only. I figured
it'd be nice to point at the new interface doc file to compensate
for removing that information, but I'd be happy to not do that and
just remove the redundant bits.
Probably some of the stuff I just wrote should go into the commit
log for the next version of the patch :)
Thanks much,
--Gabriel
On Mon, Nov 16, 2015 at 2:38 AM, Paolo Bonzini <[email protected]> wrote:
>
>
> On 15/11/2015 03:07, Rob Herring wrote:
>> We generally don't want DT docs to depend on other kernel documentation.
>
> DT docs do not contain a copy of the data sheets, either. There is no
> reason to say how to use the device (and even then, only doing so
> partially) in the DT docs.
The difference is datasheets apply to all OS's, kernel documentation
does not. In theory at least this could be used for other OS's, right?
Perhaps QEMU is the right place to thoroughly describe this and DT and
sysfs docs can refer to it.
Rob
On Tue, Nov 17, 2015 at 04:14:42PM -0600, Rob Herring wrote:
> On Mon, Nov 16, 2015 at 2:38 AM, Paolo Bonzini <[email protected]> wrote:
> >
> >
> > On 15/11/2015 03:07, Rob Herring wrote:
> >> We generally don't want DT docs to depend on other kernel documentation.
> >
> > DT docs do not contain a copy of the data sheets, either. There is no
> > reason to say how to use the device (and even then, only doing so
> > partially) in the DT docs.
>
> The difference is datasheets apply to all OS's, kernel documentation
> does not. In theory at least this could be used for other OS's, right?
>
> Perhaps QEMU is the right place to thoroughly describe this and DT and
> sysfs docs can refer to it.
So, leave only ARM/DT specifc details in
Documentation/devicetree/bindings/arm/fw-cfg.txt,
and rework the fw_cfg sysfs patch (1/4) to only document
sysfs specific details in
Documentation/ABI/testing/sysfs-firmware-qemu_fw_cfg ?
The fw_cfg "datasheet" does exist in QEMU already, so there is
something to point at from either/both of the above.
Thanks,
--Gabriel
On 17/11/2015 23:14, Rob Herring wrote:
> On Mon, Nov 16, 2015 at 2:38 AM, Paolo Bonzini <[email protected]> wrote:
>>
>>
>> On 15/11/2015 03:07, Rob Herring wrote:
>>> We generally don't want DT docs to depend on other kernel documentation.
>>
>> DT docs do not contain a copy of the data sheets, either. There is no
>> reason to say how to use the device (and even then, only doing so
>> partially) in the DT docs.
>
> The difference is datasheets apply to all OS's, kernel documentation
> does not. In theory at least this could be used for other OS's, right?
Would be nice indeed, as it's part of their intended purpose.
For now we have to shoehorn things into linux-only stuff (like initrd)
because well, nobody cares enough about NetBSD to compile U-Boot with
its internal API, so let alone adding custom Haiku code.
And of course, for things linux doesn't care about (like framebuffer
description) then we're stuck trying to guess where it's at and writing
drivers for our bootloader.
So if at least people were considering they aren't the only users of
this, that'd make life better for everyone.
> Perhaps QEMU is the right place to thoroughly describe this and DT and
> sysfs docs can refer to it.
The brilliant idea of FDT was that we could have a canonical source and
blob for it where people could send patches, but of course Linux and BSD
freaks disagreed, so you now find Linux-flavoured DTs for rPi and other
things, as well as BSD versions.
Please, at least get the binding documentation for this unique and
usable for everyone!
Fran?ois.
On Wed, Nov 18, 2015 at 02:04:24PM +0100, Fran?ois Revol wrote:
> On 17/11/2015 23:14, Rob Herring wrote:
> > On Mon, Nov 16, 2015 at 2:38 AM, Paolo Bonzini <[email protected]> wrote:
> >>
> >>
> >> On 15/11/2015 03:07, Rob Herring wrote:
> >>> We generally don't want DT docs to depend on other kernel documentation.
> >>
> >> DT docs do not contain a copy of the data sheets, either. There is no
> >> reason to say how to use the device (and even then, only doing so
> >> partially) in the DT docs.
> >
> > The difference is datasheets apply to all OS's, kernel documentation
> > does not. In theory at least this could be used for other OS's, right?
>
> Would be nice indeed, as it's part of their intended purpose.
>
> For now we have to shoehorn things into linux-only stuff (like initrd)
> because well, nobody cares enough about NetBSD to compile U-Boot with
> its internal API, so let alone adding custom Haiku code.
>
> And of course, for things linux doesn't care about (like framebuffer
> description) then we're stuck trying to guess where it's at and writing
> drivers for our bootloader.
>
> So if at least people were considering they aren't the only users of
> this, that'd make life better for everyone.
>
> > Perhaps QEMU is the right place to thoroughly describe this and DT and
> > sysfs docs can refer to it.
>
> The brilliant idea of FDT was that we could have a canonical source and
> blob for it where people could send patches, but of course Linux and BSD
> freaks disagreed, so you now find Linux-flavoured DTs for rPi and other
> things, as well as BSD versions.
>
> Please, at least get the binding documentation for this unique and
> usable for everyone!
That would be 'docs/specs/fw_cfg.txt' in the QEMU source tree. I will
avoid cut'n'pasting anything from there into either the proposed
Documentation/ABI/testing/sysfs-firmware-qemu_fw_cfg (leaving only the
sysfs specific bits in there), and also remove any redundant bits from
Documentation/devicetree/bindings/arm/fw-cfg.txt.
I'm inclined to add (in v5) a mention of 'qemu:docs/specs/fw_cfg.txt'
to both the proposed fw_cfg sysfs doc file, and to the existing fw_cfg
arm/dt node doc file, unless I get strong objections against doing so... :)
Thanks,
--Gabriel