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// SPDX-License-Identifier: GPL-2.0-only
/*
* MTD map driver for BIOS Flash on Intel SCB2 boards
* Copyright (C) 2002 Sun Microsystems, Inc.
* Tim Hockin <thockin@sun.com>
*
* A few notes on this MTD map:
*
* This was developed with a small number of SCB2 boards to test on.
* Hopefully, Intel has not introducted too many unaccounted variables in the
* making of this board.
*
* The BIOS marks its own memory region as 'reserved' in the e820 map. We
* try to request it here, but if it fails, we carry on anyway.
*
* This is how the chip is attached, so said the schematic:
* * a 4 MiB (32 Mib) 16 bit chip
* * a 1 MiB memory region
* * A20 and A21 pulled up
* * D8-D15 ignored
* What this means is that, while we are addressing bytes linearly, we are
* really addressing words, and discarding the other byte. This means that
* the chip MUST BE at least 2 MiB. This also means that every block is
* actually half as big as the chip reports. It also means that accesses of
* logical address 0 hit higher-address sections of the chip, not physical 0.
* One can only hope that these 4MiB x16 chips were a lot cheaper than 1MiB x8
* chips.
*
* This driver assumes the chip is not write-protected by an external signal.
* As of the this writing, that is true, but may change, just to spite me.
*
* The actual BIOS layout has been mostly reverse engineered. Intel BIOS
* updates for this board include 10 related (*.bio - &.bi9) binary files and
* another separate (*.bbo) binary file. The 10 files are 64k of data + a
* small header. If the headers are stripped off, the 10 64k files can be
* concatenated into a 640k image. This is your BIOS image, proper. The
* separate .bbo file also has a small header. It is the 'Boot Block'
* recovery BIOS. Once the header is stripped, no further prep is needed.
* As best I can tell, the BIOS is arranged as such:
* offset 0x00000 to 0x4ffff (320k): unknown - SCSI BIOS, etc?
* offset 0x50000 to 0xeffff (640k): BIOS proper
* offset 0xf0000 ty 0xfffff (64k): Boot Block region
*
* Intel's BIOS update program flashes the BIOS and Boot Block in separate
* steps. Probably a wise thing to do.
*/
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <asm/io.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/map.h>
#include <linux/mtd/cfi.h>
#include <linux/pci.h>
#include <linux/pci_ids.h>
#define MODNAME "scb2_flash"
#define SCB2_ADDR 0xfff00000
#define SCB2_WINDOW 0x00100000
static void __iomem *scb2_ioaddr;
static struct mtd_info *scb2_mtd;
static struct map_info scb2_map = {
.name = "SCB2 BIOS Flash",
.size = 0,
.bankwidth = 1,
};
static int region_fail;
static int scb2_fixup_mtd(struct mtd_info *mtd)
{
int i;
int done = 0;
struct map_info *map = mtd->priv;
struct cfi_private *cfi = map->fldrv_priv;
/* barf if this doesn't look right */
if (cfi->cfiq->InterfaceDesc != CFI_INTERFACE_X16_ASYNC) {
printk(KERN_ERR MODNAME ": unsupported InterfaceDesc: %#x\n",
cfi->cfiq->InterfaceDesc);
return -1;
}
/* I wasn't here. I didn't see. dwmw2. */
/* the chip is sometimes bigger than the map - what a waste */
mtd->size = map->size;
/*
* We only REALLY get half the chip, due to the way it is
* wired up - D8-D15 are tossed away. We read linear bytes,
* but in reality we are getting 1/2 of each 16-bit read,
* which LOOKS linear to us. Because CFI code accounts for
* things like lock/unlock/erase by eraseregions, we need to
* fudge them to reflect this. Erases go like this:
* * send an erase to an address
* * the chip samples the address and erases the block
* * add the block erasesize to the address and repeat
* -- the problem is that addresses are 16-bit addressable
* -- we end up erasing every-other block
*/
mtd->erasesize /= 2;
for (i = 0; i < mtd->numeraseregions; i++) {
struct mtd_erase_region_info *region = &mtd->eraseregions[i];
region->erasesize /= 2;
}
/*
* If the chip is bigger than the map, it is wired with the high
* address lines pulled up. This makes us access the top portion of
* the chip, so all our erase-region info is wrong. Start cutting from
* the bottom.
*/
for (i = 0; !done && i < mtd->numeraseregions; i++) {
struct mtd_erase_region_info *region = &mtd->eraseregions[i];
if (region->numblocks * region->erasesize > mtd->size) {
region->numblocks = ((unsigned long)mtd->size /
region->erasesize);
done = 1;
} else {
region->numblocks = 0;
}
region->offset = 0;
}
return 0;
}
/* CSB5's 'Function Control Register' has bits for decoding @ >= 0xffc00000 */
#define CSB5_FCR 0x41
#define CSB5_FCR_DECODE_ALL 0x0e
static int scb2_flash_probe(struct pci_dev *dev,
const struct pci_device_id *ent)
{
u8 reg;
/* enable decoding of the flash region in the south bridge */
pci_read_config_byte(dev, CSB5_FCR, ®);
pci_write_config_byte(dev, CSB5_FCR, reg | CSB5_FCR_DECODE_ALL);
if (!request_mem_region(SCB2_ADDR, SCB2_WINDOW, scb2_map.name)) {
/*
* The BIOS seems to mark the flash region as 'reserved'
* in the e820 map. Warn and go about our business.
*/
printk(KERN_WARNING MODNAME
": warning - can't reserve rom window, continuing\n");
region_fail = 1;
}
/* remap the IO window (w/o caching) */
scb2_ioaddr = ioremap_nocache(SCB2_ADDR, SCB2_WINDOW);
if (!scb2_ioaddr) {
printk(KERN_ERR MODNAME ": Failed to ioremap window!\n");
if (!region_fail)
release_mem_region(SCB2_ADDR, SCB2_WINDOW);
return -ENOMEM;
}
scb2_map.phys = SCB2_ADDR;
scb2_map.virt = scb2_ioaddr;
scb2_map.size = SCB2_WINDOW;
simple_map_init(&scb2_map);
/* try to find a chip */
scb2_mtd = do_map_probe("cfi_probe", &scb2_map);
if (!scb2_mtd) {
printk(KERN_ERR MODNAME ": flash probe failed!\n");
iounmap(scb2_ioaddr);
if (!region_fail)
release_mem_region(SCB2_ADDR, SCB2_WINDOW);
return -ENODEV;
}
scb2_mtd->owner = THIS_MODULE;
if (scb2_fixup_mtd(scb2_mtd) < 0) {
mtd_device_unregister(scb2_mtd);
map_destroy(scb2_mtd);
iounmap(scb2_ioaddr);
if (!region_fail)
release_mem_region(SCB2_ADDR, SCB2_WINDOW);
return -ENODEV;
}
printk(KERN_NOTICE MODNAME ": chip size 0x%llx at offset 0x%llx\n",
(unsigned long long)scb2_mtd->size,
(unsigned long long)(SCB2_WINDOW - scb2_mtd->size));
mtd_device_register(scb2_mtd, NULL, 0);
return 0;
}
static void scb2_flash_remove(struct pci_dev *dev)
{
if (!scb2_mtd)
return;
/* disable flash writes */
mtd_lock(scb2_mtd, 0, scb2_mtd->size);
mtd_device_unregister(scb2_mtd);
map_destroy(scb2_mtd);
iounmap(scb2_ioaddr);
scb2_ioaddr = NULL;
if (!region_fail)
release_mem_region(SCB2_ADDR, SCB2_WINDOW);
}
static struct pci_device_id scb2_flash_pci_ids[] = {
{
.vendor = PCI_VENDOR_ID_SERVERWORKS,
.device = PCI_DEVICE_ID_SERVERWORKS_CSB5,
.subvendor = PCI_ANY_ID,
.subdevice = PCI_ANY_ID
},
{ 0, }
};
static struct pci_driver scb2_flash_driver = {
.name = "Intel SCB2 BIOS Flash",
.id_table = scb2_flash_pci_ids,
.probe = scb2_flash_probe,
.remove = scb2_flash_remove,
};
module_pci_driver(scb2_flash_driver);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Tim Hockin <thockin@sun.com>");
MODULE_DESCRIPTION("MTD map driver for Intel SCB2 BIOS Flash");
MODULE_DEVICE_TABLE(pci, scb2_flash_pci_ids);
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