Re: Exposing ROM's though sysfs

[Jesse Barnes]

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
===== 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);