summaryrefslogtreecommitdiff
path: root/Documentation/firmware_class
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /Documentation/firmware_class
downloadkernel-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.gz
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'Documentation/firmware_class')
-rw-r--r--Documentation/firmware_class/README124
-rw-r--r--Documentation/firmware_class/firmware_sample_driver.c126
-rw-r--r--Documentation/firmware_class/firmware_sample_firmware_class.c204
-rw-r--r--Documentation/firmware_class/hotplug-script16
4 files changed, 470 insertions, 0 deletions
diff --git a/Documentation/firmware_class/README b/Documentation/firmware_class/README
new file mode 100644
index 000000000000..43e836c07ae8
--- /dev/null
+++ b/Documentation/firmware_class/README
@@ -0,0 +1,124 @@
+
+ request_firmware() hotplug interface:
+ ------------------------------------
+ Copyright (C) 2003 Manuel Estrada Sainz <ranty@debian.org>
+
+ Why:
+ ---
+
+ Today, the most extended way to use firmware in the Linux kernel is linking
+ it statically in a header file. Which has political and technical issues:
+
+ 1) Some firmware is not legal to redistribute.
+ 2) The firmware occupies memory permanently, even though it often is just
+ used once.
+ 3) Some people, like the Debian crowd, don't consider some firmware free
+ enough and remove entire drivers (e.g.: keyspan).
+
+ High level behavior (mixed):
+ ============================
+
+ kernel(driver): calls request_firmware(&fw_entry, $FIRMWARE, device)
+
+ userspace:
+ - /sys/class/firmware/xxx/{loading,data} appear.
+ - hotplug gets called with a firmware identifier in $FIRMWARE
+ and the usual hotplug environment.
+ - hotplug: echo 1 > /sys/class/firmware/xxx/loading
+
+ kernel: Discard any previous partial load.
+
+ userspace:
+ - hotplug: cat appropriate_firmware_image > \
+ /sys/class/firmware/xxx/data
+
+ kernel: grows a buffer in PAGE_SIZE increments to hold the image as it
+ comes in.
+
+ userspace:
+ - hotplug: echo 0 > /sys/class/firmware/xxx/loading
+
+ kernel: request_firmware() returns and the driver has the firmware
+ image in fw_entry->{data,size}. If something went wrong
+ request_firmware() returns non-zero and fw_entry is set to
+ NULL.
+
+ kernel(driver): Driver code calls release_firmware(fw_entry) releasing
+ the firmware image and any related resource.
+
+ High level behavior (driver code):
+ ==================================
+
+ if(request_firmware(&fw_entry, $FIRMWARE, device) == 0)
+ copy_fw_to_device(fw_entry->data, fw_entry->size);
+ release(fw_entry);
+
+ Sample/simple hotplug script:
+ ============================
+
+ # Both $DEVPATH and $FIRMWARE are already provided in the environment.
+
+ HOTPLUG_FW_DIR=/usr/lib/hotplug/firmware/
+
+ echo 1 > /sys/$DEVPATH/loading
+ cat $HOTPLUG_FW_DIR/$FIRMWARE > /sysfs/$DEVPATH/data
+ echo 0 > /sys/$DEVPATH/loading
+
+ Random notes:
+ ============
+
+ - "echo -1 > /sys/class/firmware/xxx/loading" will cancel the load at
+ once and make request_firmware() return with error.
+
+ - firmware_data_read() and firmware_loading_show() are just provided
+ for testing and completeness, they are not called in normal use.
+
+ - There is also /sys/class/firmware/timeout which holds a timeout in
+ seconds for the whole load operation.
+
+ - request_firmware_nowait() is also provided for convenience in
+ non-user contexts.
+
+
+ about in-kernel persistence:
+ ---------------------------
+ Under some circumstances, as explained below, it would be interesting to keep
+ firmware images in non-swappable kernel memory or even in the kernel image
+ (probably within initramfs).
+
+ Note that this functionality has not been implemented.
+
+ - Why OPTIONAL in-kernel persistence may be a good idea sometimes:
+
+ - If the device that needs the firmware is needed to access the
+ filesystem. When upon some error the device has to be reset and the
+ firmware reloaded, it won't be possible to get it from userspace.
+ e.g.:
+ - A diskless client with a network card that needs firmware.
+ - The filesystem is stored in a disk behind an scsi device
+ that needs firmware.
+ - Replacing buggy DSDT/SSDT ACPI tables on boot.
+ Note: this would require the persistent objects to be included
+ within the kernel image, probably within initramfs.
+
+ And the same device can be needed to access the filesystem or not depending
+ on the setup, so I think that the choice on what firmware to make
+ persistent should be left to userspace.
+
+ - Why register_firmware()+__init can be useful:
+ - For boot devices needing firmware.
+ - To make the transition easier:
+ The firmware can be declared __init and register_firmware()
+ called on module_init. Then the firmware is warranted to be
+ there even if "firmware hotplug userspace" is not there yet or
+ it doesn't yet provide the needed firmware.
+ Once the firmware is widely available in userspace, it can be
+ removed from the kernel. Or made optional (CONFIG_.*_FIRMWARE).
+
+ In either case, if firmware hotplug support is there, it can move the
+ firmware out of kernel memory into the real filesystem for later
+ usage.
+
+ Note: If persistence is implemented on top of initramfs,
+ register_firmware() may not be appropriate.
+
diff --git a/Documentation/firmware_class/firmware_sample_driver.c b/Documentation/firmware_class/firmware_sample_driver.c
new file mode 100644
index 000000000000..e1c56a7e6583
--- /dev/null
+++ b/Documentation/firmware_class/firmware_sample_driver.c
@@ -0,0 +1,126 @@
+/*
+ * firmware_sample_driver.c -
+ *
+ * Copyright (c) 2003 Manuel Estrada Sainz <ranty@debian.org>
+ *
+ * Sample code on how to use request_firmware() from drivers.
+ *
+ * Note that register_firmware() is currently useless.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/device.h>
+
+#include "linux/firmware.h"
+
+#define WE_CAN_NEED_FIRMWARE_BEFORE_USERSPACE_IS_AVAILABLE
+#ifdef WE_CAN_NEED_FIRMWARE_BEFORE_USERSPACE_IS_AVAILABLE
+char __init inkernel_firmware[] = "let's say that this is firmware\n";
+#endif
+
+static struct device ghost_device = {
+ .name = "Ghost Device",
+ .bus_id = "ghost0",
+};
+
+
+static void sample_firmware_load(char *firmware, int size)
+{
+ u8 buf[size+1];
+ memcpy(buf, firmware, size);
+ buf[size] = '\0';
+ printk("firmware_sample_driver: firmware: %s\n", buf);
+}
+
+static void sample_probe_default(void)
+{
+ /* uses the default method to get the firmware */
+ const struct firmware *fw_entry;
+ printk("firmware_sample_driver: a ghost device got inserted :)\n");
+
+ if(request_firmware(&fw_entry, "sample_driver_fw", &ghost_device)!=0)
+ {
+ printk(KERN_ERR
+ "firmware_sample_driver: Firmware not available\n");
+ return;
+ }
+
+ sample_firmware_load(fw_entry->data, fw_entry->size);
+
+ release_firmware(fw_entry);
+
+ /* finish setting up the device */
+}
+static void sample_probe_specific(void)
+{
+ /* Uses some specific hotplug support to get the firmware from
+ * userspace directly into the hardware, or via some sysfs file */
+
+ /* NOTE: This currently doesn't work */
+
+ printk("firmware_sample_driver: a ghost device got inserted :)\n");
+
+ if(request_firmware(NULL, "sample_driver_fw", &ghost_device)!=0)
+ {
+ printk(KERN_ERR
+ "firmware_sample_driver: Firmware load failed\n");
+ return;
+ }
+
+ /* request_firmware blocks until userspace finished, so at
+ * this point the firmware should be already in the device */
+
+ /* finish setting up the device */
+}
+static void sample_probe_async_cont(const struct firmware *fw, void *context)
+{
+ if(!fw){
+ printk(KERN_ERR
+ "firmware_sample_driver: firmware load failed\n");
+ return;
+ }
+
+ printk("firmware_sample_driver: device pointer \"%s\"\n",
+ (char *)context);
+ sample_firmware_load(fw->data, fw->size);
+}
+static void sample_probe_async(void)
+{
+ /* Let's say that I can't sleep */
+ int error;
+ error = request_firmware_nowait (THIS_MODULE,
+ "sample_driver_fw", &ghost_device,
+ "my device pointer",
+ sample_probe_async_cont);
+ if(error){
+ printk(KERN_ERR
+ "firmware_sample_driver:"
+ " request_firmware_nowait failed\n");
+ }
+}
+
+static int sample_init(void)
+{
+#ifdef WE_CAN_NEED_FIRMWARE_BEFORE_USERSPACE_IS_AVAILABLE
+ register_firmware("sample_driver_fw", inkernel_firmware,
+ sizeof(inkernel_firmware));
+#endif
+ device_initialize(&ghost_device);
+ /* since there is no real hardware insertion I just call the
+ * sample probe functions here */
+ sample_probe_specific();
+ sample_probe_default();
+ sample_probe_async();
+ return 0;
+}
+static void __exit sample_exit(void)
+{
+}
+
+module_init (sample_init);
+module_exit (sample_exit);
+
+MODULE_LICENSE("GPL");
diff --git a/Documentation/firmware_class/firmware_sample_firmware_class.c b/Documentation/firmware_class/firmware_sample_firmware_class.c
new file mode 100644
index 000000000000..09eab2f1b373
--- /dev/null
+++ b/Documentation/firmware_class/firmware_sample_firmware_class.c
@@ -0,0 +1,204 @@
+/*
+ * firmware_sample_firmware_class.c -
+ *
+ * Copyright (c) 2003 Manuel Estrada Sainz <ranty@debian.org>
+ *
+ * NOTE: This is just a probe of concept, if you think that your driver would
+ * be well served by this mechanism please contact me first.
+ *
+ * DON'T USE THIS CODE AS IS
+ *
+ */
+
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/timer.h>
+#include <linux/firmware.h>
+
+
+MODULE_AUTHOR("Manuel Estrada Sainz <ranty@debian.org>");
+MODULE_DESCRIPTION("Hackish sample for using firmware class directly");
+MODULE_LICENSE("GPL");
+
+static inline struct class_device *to_class_dev(struct kobject *obj)
+{
+ return container_of(obj,struct class_device,kobj);
+}
+static inline
+struct class_device_attribute *to_class_dev_attr(struct attribute *_attr)
+{
+ return container_of(_attr,struct class_device_attribute,attr);
+}
+
+int sysfs_create_bin_file(struct kobject * kobj, struct bin_attribute * attr);
+int sysfs_remove_bin_file(struct kobject * kobj, struct bin_attribute * attr);
+
+struct firmware_priv {
+ char fw_id[FIRMWARE_NAME_MAX];
+ s32 loading:2;
+ u32 abort:1;
+};
+
+extern struct class firmware_class;
+
+static ssize_t firmware_loading_show(struct class_device *class_dev, char *buf)
+{
+ struct firmware_priv *fw_priv = class_get_devdata(class_dev);
+ return sprintf(buf, "%d\n", fw_priv->loading);
+}
+static ssize_t firmware_loading_store(struct class_device *class_dev,
+ const char *buf, size_t count)
+{
+ struct firmware_priv *fw_priv = class_get_devdata(class_dev);
+ int prev_loading = fw_priv->loading;
+
+ fw_priv->loading = simple_strtol(buf, NULL, 10);
+
+ switch(fw_priv->loading){
+ case -1:
+ /* abort load an panic */
+ break;
+ case 1:
+ /* setup load */
+ break;
+ case 0:
+ if(prev_loading==1){
+ /* finish load and get the device back to working
+ * state */
+ }
+ break;
+ }
+
+ return count;
+}
+static CLASS_DEVICE_ATTR(loading, 0644,
+ firmware_loading_show, firmware_loading_store);
+
+static ssize_t firmware_data_read(struct kobject *kobj,
+ char *buffer, loff_t offset, size_t count)
+{
+ struct class_device *class_dev = to_class_dev(kobj);
+ struct firmware_priv *fw_priv = class_get_devdata(class_dev);
+
+ /* read from the devices firmware memory */
+
+ return count;
+}
+static ssize_t firmware_data_write(struct kobject *kobj,
+ char *buffer, loff_t offset, size_t count)
+{
+ struct class_device *class_dev = to_class_dev(kobj);
+ struct firmware_priv *fw_priv = class_get_devdata(class_dev);
+
+ /* write to the devices firmware memory */
+
+ return count;
+}
+static struct bin_attribute firmware_attr_data = {
+ .attr = {.name = "data", .mode = 0644},
+ .size = 0,
+ .read = firmware_data_read,
+ .write = firmware_data_write,
+};
+static int fw_setup_class_device(struct class_device *class_dev,
+ const char *fw_name,
+ struct device *device)
+{
+ int retval = 0;
+ struct firmware_priv *fw_priv = kmalloc(sizeof(struct firmware_priv),
+ GFP_KERNEL);
+
+ if(!fw_priv){
+ retval = -ENOMEM;
+ goto out;
+ }
+ memset(fw_priv, 0, sizeof(*fw_priv));
+ memset(class_dev, 0, sizeof(*class_dev));
+
+ strncpy(fw_priv->fw_id, fw_name, FIRMWARE_NAME_MAX);
+ fw_priv->fw_id[FIRMWARE_NAME_MAX-1] = '\0';
+
+ strncpy(class_dev->class_id, device->bus_id, BUS_ID_SIZE);
+ class_dev->class_id[BUS_ID_SIZE-1] = '\0';
+ class_dev->dev = device;
+
+ class_dev->class = &firmware_class,
+ class_set_devdata(class_dev, fw_priv);
+ retval = class_device_register(class_dev);
+ if (retval){
+ printk(KERN_ERR "%s: class_device_register failed\n",
+ __FUNCTION__);
+ goto error_free_fw_priv;
+ }
+
+ retval = sysfs_create_bin_file(&class_dev->kobj, &firmware_attr_data);
+ if (retval){
+ printk(KERN_ERR "%s: sysfs_create_bin_file failed\n",
+ __FUNCTION__);
+ goto error_unreg_class_dev;
+ }
+
+ retval = class_device_create_file(class_dev,
+ &class_device_attr_loading);
+ if (retval){
+ printk(KERN_ERR "%s: class_device_create_file failed\n",
+ __FUNCTION__);
+ goto error_remove_data;
+ }
+
+ goto out;
+
+error_remove_data:
+ sysfs_remove_bin_file(&class_dev->kobj, &firmware_attr_data);
+error_unreg_class_dev:
+ class_device_unregister(class_dev);
+error_free_fw_priv:
+ kfree(fw_priv);
+out:
+ return retval;
+}
+static void fw_remove_class_device(struct class_device *class_dev)
+{
+ struct firmware_priv *fw_priv = class_get_devdata(class_dev);
+
+ class_device_remove_file(class_dev, &class_device_attr_loading);
+ sysfs_remove_bin_file(&class_dev->kobj, &firmware_attr_data);
+ class_device_unregister(class_dev);
+}
+
+static struct class_device *class_dev;
+
+static struct device my_device = {
+ .name = "Sample Device",
+ .bus_id = "my_dev0",
+};
+
+static int __init firmware_sample_init(void)
+{
+ int error;
+
+ device_initialize(&my_device);
+ class_dev = kmalloc(sizeof(struct class_device), GFP_KERNEL);
+ if(!class_dev)
+ return -ENOMEM;
+
+ error = fw_setup_class_device(class_dev, "my_firmware_image",
+ &my_device);
+ if(error){
+ kfree(class_dev);
+ return error;
+ }
+ return 0;
+
+}
+static void __exit firmware_sample_exit(void)
+{
+ struct firmware_priv *fw_priv = class_get_devdata(class_dev);
+ fw_remove_class_device(class_dev);
+ kfree(fw_priv);
+ kfree(class_dev);
+}
+module_init(firmware_sample_init);
+module_exit(firmware_sample_exit);
+
diff --git a/Documentation/firmware_class/hotplug-script b/Documentation/firmware_class/hotplug-script
new file mode 100644
index 000000000000..1990130f2ab1
--- /dev/null
+++ b/Documentation/firmware_class/hotplug-script
@@ -0,0 +1,16 @@
+#!/bin/sh
+
+# Simple hotplug script sample:
+#
+# Both $DEVPATH and $FIRMWARE are already provided in the environment.
+
+HOTPLUG_FW_DIR=/usr/lib/hotplug/firmware/
+
+echo 1 > /sys/$DEVPATH/loading
+cat $HOTPLUG_FW_DIR/$FIRMWARE > /sys/$DEVPATH/data
+echo 0 > /sys/$DEVPATH/loading
+
+# To cancel the load in case of error:
+#
+# echo -1 > /sys/$DEVPATH/loading
+#