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authorChris Metcalf <cmetcalf@tilera.com>2011-06-10 13:07:48 -0400
committerChris Metcalf <cmetcalf@tilera.com>2011-06-10 13:07:48 -0400
commitdbcb4a1a3f16702918caa4d4ab7062965050a780 (patch)
tree0b42ff1e6f8d82e07263975705d944bc4d41d184 /arch/tile/include
parentea41b1e5440442cea5c029b192e9ebbe68e423f6 (diff)
downloadlinux-dbcb4a1a3f16702918caa4d4ab7062965050a780.tar.bz2
arch/tile: add hypervisor-based character driver for SPI flash ROM
The first version of this patch proposed an arch/tile/drivers/ directory, but the consensus was that this was probably a poor choice for a place to group Tilera-specific drivers, and that in any case grouping by platform was discouraged, and grouping by function was preferred. This version of the patch addresses various issues raised in the community, primarily the absence of sysfs integration. The sysfs integration now handles passing information on sector size, page size, and total partition size to userspace as well. In addition, we now use a single "struct cdev" to manage all the partition minor devices, and dynamically discover the correct number of partitions from the hypervisor rather than using a module_param with a default value. This driver has no particular "peer" drivers it can be grouped with. It is sort of like an MTD driver for SPI ROM, but it doesn't group well with the other MTD devices since it relies on hypervisor virtualization to handle many of the irritating aspects of flash ROM management: sector awareness, background read for sub-sector writes, bit examination to determine whether a sector erase needs to be issued, etc. It is in fact more like an EEPROM driver, but the hypervisor virtualization does require a "flush" command if you wish to commit a sector write prior to writing to a different sector, and this is sufficiently different from generic I2C/SPI EEPROMs that as a result it doesn't group well with them either. The simple character device is already in use by a range of Tilera SPI ROM management tools, as well as by customers. In addition, using the simple character device actually simplifies the userspace tools, since they don't need to manage sector erase, background read, etc. This both simplifies the code (since we can uniformly manage plain files and the SPI ROM) as well as makes the user code portable to non-Linux platforms that don't offer the same MTD ioctls. Signed-off-by: Chris Metcalf <cmetcalf@tilera.com> Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Diffstat (limited to 'arch/tile/include')
-rw-r--r--arch/tile/include/hv/drv_srom_intf.h41
1 files changed, 41 insertions, 0 deletions
diff --git a/arch/tile/include/hv/drv_srom_intf.h b/arch/tile/include/hv/drv_srom_intf.h
new file mode 100644
index 000000000000..6395faa6d9e6
--- /dev/null
+++ b/arch/tile/include/hv/drv_srom_intf.h
@@ -0,0 +1,41 @@
+/*
+ * Copyright 2011 Tilera Corporation. All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, version 2.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ * NON INFRINGEMENT. See the GNU General Public License for
+ * more details.
+ */
+
+/**
+ * @file drv_srom_intf.h
+ * Interface definitions for the SPI Flash ROM driver.
+ */
+
+#ifndef _SYS_HV_INCLUDE_DRV_SROM_INTF_H
+#define _SYS_HV_INCLUDE_DRV_SROM_INTF_H
+
+/** Read this offset to get the total device size. */
+#define SROM_TOTAL_SIZE_OFF 0xF0000000
+
+/** Read this offset to get the device sector size. */
+#define SROM_SECTOR_SIZE_OFF 0xF0000004
+
+/** Read this offset to get the device page size. */
+#define SROM_PAGE_SIZE_OFF 0xF0000008
+
+/** Write this offset to flush any pending writes. */
+#define SROM_FLUSH_OFF 0xF1000000
+
+/** Write this offset, plus the byte offset of the start of a sector, to
+ * erase a sector. Any write data is ignored, but there must be at least
+ * one byte of write data. Only applies when the driver is in MTD mode.
+ */
+#define SROM_ERASE_OFF 0xF2000000
+
+#endif /* _SYS_HV_INCLUDE_DRV_SROM_INTF_H */