[PATCH] DRIVER: request_firmware() hotplug interface documentation

diff --git a/Documentation/firmware_class/README b/Documentation/firmware_class/README
new file mode 100644 (file)
index 0000000..4b2c74f
--- /dev/null
+++ b/Documentation/firmware_class/README
@@ -0,0 +1,58 @@
+
+ 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).
+
+ 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 (file)
index 0000000..e1c56a7
--- /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 (file)
index 0000000..037c0be
--- /dev/null
+++ b/Documentation/firmware_class/firmware_sample_firmware_class.c
@@ -0,0 +1,205 @@
+/*
+ * 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 <asm/hardirq.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 (file)
index 0000000..0a31bcd
--- /dev/null
+++ b/Documentation/firmware_class/hotplug-script
@@ -0,0 +1,16 @@
+#!/bin/sh
+
+# Simple hotplug script sample:
+# 
+# Both $DEVPATH and $FIRMWARE are already provided in the environment.
+
+HOTPLUG_FW_DIR=/usr/lib/hotplug/firmware/
+
+echo 1 > /sysfs/$DEVPATH/loading
+cat $HOTPLUG_FW_DIR/$FIRMWARE > /sysfs/$DEVPATH/data
+echo 0 > /sysfs/$DEVPATH/loading
+
+# To cancel the load in case of error:
+#
+#      echo -1 > /sysfs/$DEVPATH/loading
+#