Re: [PATCH] add PCI ROMs to sysfs

[Jesse Barnes <jbarnes@engr.sgi.com>]

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On Friday, July 30, 2004 2:34 pm, Jesse Barnes wrote:
> On Friday, July 30, 2004 2:29 pm, Greg KH wrote:
> > On Fri, Jul 30, 2004 at 02:09:05PM -0700, Jesse Barnes wrote:
> > > Thoughts?  I've tried to add cleanup code, but I'm not sure how
> > > acceptable it is and I don't have any way of testing it.
> >
> > You don't have access to a cardbus machine?  Or how about using the
> > fakephp driver to "remove" pci devices?  You should be able to test this
> > code path with either one of those methods...
>
> I've never tried fakephp, I'll look into it.  And I do have a laptop at
> home that I could mess around on too, though I don't think I have any
> devices with ROMs...

Ok, I tested it with fakephp and things seem to work ok (no panics, all files 
are removed).

Does it look ok otherwise?

Thanks,
Jesse

[-- Attachment #2: pci-sysfs-rom-6.patch --]
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===== drivers/pci/pci-sysfs.c 1.10 vs edited =====
--- 1.10/drivers/pci/pci-sysfs.c	2004-06-04 06:23:04 -07:00
+++ edited/drivers/pci/pci-sysfs.c	2004-07-30 14:37:04 -07:00
@@ -164,6 +164,86 @@
 	return count;
 }
 
+/**
+ * pci_enable_rom - enable ROM decoding for a PCI device
+ * @dev: PCI device to enable
+ *
+ * Enable ROM decoding on @dev.  This involves simply turning on the last
+ * bit of the PCI ROM BAR.  Note that some cards may share address decoders
+ * between the ROM and other resources, so enabling it may disable access
+ * to MMIO registers or other card memory.
+ */
+static void
+pci_enable_rom(struct pci_dev *dev)
+{
+	u32 rom_addr;
+
+	pci_read_config_dword(dev, PCI_ROM_ADDRESS, &rom_addr);
+	rom_addr |= PCI_ROM_ADDRESS_ENABLE;
+	pci_write_config_dword(dev, PCI_ROM_ADDRESS, rom_addr);
+}
+
+/**
+ * pci_disable_rom - disable ROM decoding for a PCI device
+ * @dev: PCI device to disable
+ *
+ * Disable ROM decoding on a PCI device by turning off the last bit in the
+ * ROM BAR.
+ */
+static void
+pci_disable_rom(struct pci_dev *dev)
+{
+	u32 rom_addr;
+
+	pci_read_config_dword(dev, PCI_ROM_ADDRESS, &rom_addr);
+	rom_addr &= ~PCI_ROM_ADDRESS_ENABLE;
+	pci_write_config_dword(dev, PCI_ROM_ADDRESS, rom_addr);
+}
+
+/**
+ * pci_read_rom - read a PCI ROM
+ * @kobj: kernel object handle
+ * @buf: where to put the data we read from the ROM
+ * @off: file offset
+ * @count: number of bytes to read
+ *
+ * Put @count bytes starting at @off into @buf from the ROM in the PCI
+ * device corresponding to @kobj.
+ */
+static ssize_t
+pci_read_rom(struct kobject *kobj, char *buf, loff_t off, size_t count)
+{
+	struct pci_dev *dev = to_pci_dev(container_of(kobj,struct device,kobj));
+	loff_t init_off = off;
+	unsigned long start = pci_resource_start(dev, PCI_ROM_RESOURCE);
+	int size = pci_resource_len(dev, PCI_ROM_RESOURCE);
+
+	if (off > size)
+		return 0;
+	if (off + count > size) {
+		size -= off;
+		count = size;
+	} else {
+		size = count;
+	}
+
+	/* Enable ROM space decodes and do the reads */
+	pci_enable_rom(dev);
+
+	while (size > 0) {
+		unsigned char val;
+		val = readb(start + off);
+		buf[off - init_off] = val;
+		off++;
+		--size;
+	}
+
+	/* Disable again before continuing */
+	pci_disable_rom(dev);
+
+	return count;
+}
+
 static struct bin_attribute pci_config_attr = {
 	.attr =	{
 		.name = "config",
@@ -193,6 +273,43 @@
 	else
 		sysfs_create_bin_file(&pdev->dev.kobj, &pcie_config_attr);
 
+	/* If the device has a ROM, try to expose it in sysfs. */
+	if (pci_resource_len(pdev, PCI_ROM_RESOURCE)) {
+		struct bin_attribute *rom_attr;
+		rom_attr = kmalloc(sizeof(*rom_attr), GFP_ATOMIC);
+
+		pdev->rom_attr = NULL;
+		if (!rom_attr)
+			goto out;
+
+		pdev->rom_attr = rom_attr;
+		rom_attr->attr.name = "rom";
+		rom_attr->attr.mode = S_IRUSR;
+		rom_attr->attr.owner = THIS_MODULE;
+		rom_attr->read = pci_read_rom;
+		rom_attr->size = pci_resource_len(pdev, PCI_ROM_RESOURCE);
+		sysfs_create_bin_file(&pdev->dev.kobj, rom_attr);
+	}
+ out:
 	/* add platform-specific attributes */
 	pcibios_add_platform_entries(pdev);
+}
+
+/**
+ * pci_remove_sysfs_dev_files - cleanup PCI specific sysfs files
+ * @pdev: device whose entries we should free
+ *
+ * Cleanup when @pdev is removed from sysfs.
+ */
+void pci_remove_sysfs_dev_files(struct pci_dev *pdev)
+{
+	if (pdev->cfg_size < 4096)
+		sysfs_remove_bin_file(&pdev->dev.kobj, &pci_config_attr);
+	else
+		sysfs_remove_bin_file(&pdev->dev.kobj, &pcie_config_attr);
+
+	if (pci_resource_len(pdev, PCI_ROM_RESOURCE) && pdev->rom_attr) {
+		sysfs_remove_bin_file(&pdev->dev.kobj, pdev->rom_attr);
+		kfree(pdev->rom_attr);
+	}
 }
===== drivers/pci/remove.c 1.3 vs edited =====
--- 1.3/drivers/pci/remove.c	2004-02-03 09:17:30 -08:00
+++ edited/drivers/pci/remove.c	2004-07-30 13:35:18 -07:00
@@ -26,6 +26,7 @@
 static void pci_destroy_dev(struct pci_dev *dev)
 {
 	pci_proc_detach_device(dev);
+	pci_remove_sysfs_dev_files(dev);
 	device_unregister(&dev->dev);
 
 	/* Remove the device from the device lists, and prevent any further
===== include/linux/pci.h 1.130 vs edited =====
--- 1.130/include/linux/pci.h	2004-06-30 11:21:27 -07:00
+++ edited/include/linux/pci.h	2004-07-30 13:37:09 -07:00
@@ -537,6 +537,7 @@
 	unsigned int	is_busmaster:1; /* device is busmaster */
 	
 	unsigned int 	saved_config_space[16]; /* config space saved at suspend time */
+	struct bin_attribute *rom_attr; /* ROM attribute (if ROM is present) */
 #ifdef CONFIG_PCI_NAMES
 #define PCI_NAME_SIZE	96
 #define PCI_NAME_HALF	__stringify(43)	/* less than half to handle slop */