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path: root/drivers/mtd/maps/amd76xrom.c
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Diffstat (limited to 'drivers/mtd/maps/amd76xrom.c')
-rw-r--r--drivers/mtd/maps/amd76xrom.c34
1 files changed, 28 insertions, 6 deletions
diff --git a/drivers/mtd/maps/amd76xrom.c b/drivers/mtd/maps/amd76xrom.c
index 797caffb20b1..78b671172bb2 100644
--- a/drivers/mtd/maps/amd76xrom.c
+++ b/drivers/mtd/maps/amd76xrom.c
@@ -7,6 +7,7 @@
#include <linux/module.h>
#include <linux/types.h>
+#include <linux/version.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <asm/io.h>
@@ -44,6 +45,23 @@ struct amd76xrom_map_info {
char map_name[sizeof(MOD_NAME) + 2 + ADDRESS_NAME_LEN];
};
+/* The 2 bits controlling the window size are often set to allow reading
+ * the BIOS, but too small to allow writing, since the lock registers are
+ * 4MiB lower in the address space than the data.
+ *
+ * This is intended to prevent flashing the bios, perhaps accidentally.
+ *
+ * This parameter allows the normal driver to over-ride the BIOS settings.
+ *
+ * The bits are 6 and 7. If both bits are set, it is a 5MiB window.
+ * If only the 7 Bit is set, it is a 4MiB window. Otherwise, a
+ * 64KiB window.
+ *
+ */
+static uint win_size_bits;
+module_param(win_size_bits, uint, 0);
+MODULE_PARM_DESC(win_size_bits, "ROM window size bits override for 0x43 byte, normally set by BIOS.");
+
static struct amd76xrom_window amd76xrom_window = {
.maps = LIST_HEAD_INIT(amd76xrom_window.maps),
};
@@ -95,6 +113,16 @@ static int __devinit amd76xrom_init_one (struct pci_dev *pdev,
/* Remember the pci dev I find the window in - already have a ref */
window->pdev = pdev;
+ /* Enable the selected rom window. This is often incorrectly
+ * set up by the BIOS, and the 4MiB offset for the lock registers
+ * requires the full 5MiB of window space.
+ *
+ * This 'write, then read' approach leaves the bits for
+ * other uses of the hardware info.
+ */
+ pci_read_config_byte(pdev, 0x43, &byte);
+ pci_write_config_byte(pdev, 0x43, byte | win_size_bits );
+
/* Assume the rom window is properly setup, and find it's size */
pci_read_config_byte(pdev, 0x43, &byte);
if ((byte & ((1<<7)|(1<<6))) == ((1<<7)|(1<<6))) {
@@ -129,12 +157,6 @@ static int __devinit amd76xrom_init_one (struct pci_dev *pdev,
(unsigned long long)window->rsrc.end);
}
-#if 0
-
- /* Enable the selected rom window */
- pci_read_config_byte(pdev, 0x43, &byte);
- pci_write_config_byte(pdev, 0x43, byte | rwindow->segen_bits);
-#endif
/* Enable writes through the rom window */
pci_read_config_byte(pdev, 0x40, &byte);
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