Re: Exposing ROM's though sysfs

Jesse Barnes
2004-07-30T18:55:41Z

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On Friday, July 30, 2004 11:12 am, Jesse Barnes wrote:
> On Friday, July 30, 2004 11:12 am, Matthew Wilcox wrote:
> > How about reading the contents of the ROM at pci_scan_bus() time? It'd
> > waste a bunch of memory, but hey, people love sysfs.
>
> That might be a good solution, actually. Then it would be cached for
> devices that don't want you to look at it after they've been POSTed too.

Here's a version that actually works, but without the caching (i.e. don't
access it after a driver starts using the card). If we go that route, should
we hang a copy of the ROM off of the pci_dev in a pointer or somewhere else?

Thanks,
Jesse

[-- Attachment #2: pci-sysfs-rom-3.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 11:47:26 -07:00
@@ -164,6 +164,60 @@
return count;
}

+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);
+}
+
+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);
+}
+
+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",
@@ -186,12 +240,27 @@
.write = pci_write_config,
};

+static struct bin_attribute pci_rom_attr = {
+ .attr = {
+ .name = "rom",
+ .mode = S_IRUSR,
+ .owner = THIS_MODULE,
+ },
+ .read = pci_read_rom,
+};
+
void pci_create_sysfs_dev_files (struct pci_dev *pdev)
{
if (pdev->cfg_size < 4096)
sysfs_create_bin_file(&pdev->dev.kobj, &pci_config_attr);
else
sysfs_create_bin_file(&pdev->dev.kobj, &pcie_config_attr);
+
+ /* If the device has a ROM, map it */
+ if (pci_resource_len(pdev, PCI_ROM_RESOURCE)) {
+ pci_rom_attr.size = pci_resource_len(pdev, PCI_ROM_RESOURCE);
+ sysfs_create_bin_file(&pdev->dev.kobj, &pci_rom_attr);
+ }

/* add platform-specific attributes */
pcibios_add_platform_entries(pdev);