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545 lines
14 KiB
545 lines
14 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* CMOS/NV-RAM driver for Linux |
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* |
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* Copyright (C) 1997 Roman Hodek <[email protected]> |
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* idea by and with help from Richard Jelinek <[email protected]> |
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* Portions copyright (c) 2001,2002 Sun Microsystems ([email protected]) |
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* |
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* This driver allows you to access the contents of the non-volatile memory in |
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* the mc146818rtc.h real-time clock. This chip is built into all PCs and into |
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* many Atari machines. In the former it's called "CMOS-RAM", in the latter |
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* "NVRAM" (NV stands for non-volatile). |
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* |
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* The data are supplied as a (seekable) character device, /dev/nvram. The |
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* size of this file is dependent on the controller. The usual size is 114, |
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* the number of freely available bytes in the memory (i.e., not used by the |
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* RTC itself). |
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* |
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* Checksums over the NVRAM contents are managed by this driver. In case of a |
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* bad checksum, reads and writes return -EIO. The checksum can be initialized |
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* to a sane state either by ioctl(NVRAM_INIT) (clear whole NVRAM) or |
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* ioctl(NVRAM_SETCKS) (doesn't change contents, just makes checksum valid |
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* again; use with care!) |
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* |
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* 1.1 Cesar Barros: SMP locking fixes |
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* added changelog |
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* 1.2 Erik Gilling: Cobalt Networks support |
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* Tim Hockin: general cleanup, Cobalt support |
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* 1.3 Wim Van Sebroeck: convert PRINT_PROC to seq_file |
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*/ |
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|
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#define NVRAM_VERSION "1.3" |
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|
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#include <linux/module.h> |
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#include <linux/nvram.h> |
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#include <linux/types.h> |
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#include <linux/errno.h> |
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#include <linux/miscdevice.h> |
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#include <linux/ioport.h> |
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#include <linux/fcntl.h> |
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#include <linux/mc146818rtc.h> |
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#include <linux/init.h> |
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#include <linux/proc_fs.h> |
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#include <linux/seq_file.h> |
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#include <linux/slab.h> |
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#include <linux/spinlock.h> |
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#include <linux/io.h> |
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#include <linux/uaccess.h> |
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#include <linux/mutex.h> |
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#include <linux/pagemap.h> |
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|
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#ifdef CONFIG_PPC |
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#include <asm/nvram.h> |
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#endif |
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static DEFINE_MUTEX(nvram_mutex); |
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static DEFINE_SPINLOCK(nvram_state_lock); |
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static int nvram_open_cnt; /* #times opened */ |
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static int nvram_open_mode; /* special open modes */ |
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static ssize_t nvram_size; |
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#define NVRAM_WRITE 1 /* opened for writing (exclusive) */ |
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#define NVRAM_EXCL 2 /* opened with O_EXCL */ |
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|
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#ifdef CONFIG_X86 |
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/* |
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* These functions are provided to be called internally or by other parts of |
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* the kernel. It's up to the caller to ensure correct checksum before reading |
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* or after writing (needs to be done only once). |
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* |
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* It is worth noting that these functions all access bytes of general |
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* purpose memory in the NVRAM - that is to say, they all add the |
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* NVRAM_FIRST_BYTE offset. Pass them offsets into NVRAM as if you did not |
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* know about the RTC cruft. |
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*/ |
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#define NVRAM_BYTES (128 - NVRAM_FIRST_BYTE) |
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|
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/* Note that *all* calls to CMOS_READ and CMOS_WRITE must be done with |
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* rtc_lock held. Due to the index-port/data-port design of the RTC, we |
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* don't want two different things trying to get to it at once. (e.g. the |
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* periodic 11 min sync from kernel/time/ntp.c vs. this driver.) |
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*/ |
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static unsigned char __nvram_read_byte(int i) |
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{ |
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return CMOS_READ(NVRAM_FIRST_BYTE + i); |
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} |
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static unsigned char pc_nvram_read_byte(int i) |
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{ |
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unsigned long flags; |
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unsigned char c; |
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spin_lock_irqsave(&rtc_lock, flags); |
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c = __nvram_read_byte(i); |
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spin_unlock_irqrestore(&rtc_lock, flags); |
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return c; |
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} |
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/* This races nicely with trying to read with checksum checking (nvram_read) */ |
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static void __nvram_write_byte(unsigned char c, int i) |
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{ |
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CMOS_WRITE(c, NVRAM_FIRST_BYTE + i); |
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} |
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static void pc_nvram_write_byte(unsigned char c, int i) |
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{ |
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unsigned long flags; |
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spin_lock_irqsave(&rtc_lock, flags); |
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__nvram_write_byte(c, i); |
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spin_unlock_irqrestore(&rtc_lock, flags); |
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} |
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/* On PCs, the checksum is built only over bytes 2..31 */ |
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#define PC_CKS_RANGE_START 2 |
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#define PC_CKS_RANGE_END 31 |
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#define PC_CKS_LOC 32 |
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static int __nvram_check_checksum(void) |
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{ |
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int i; |
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unsigned short sum = 0; |
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unsigned short expect; |
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for (i = PC_CKS_RANGE_START; i <= PC_CKS_RANGE_END; ++i) |
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sum += __nvram_read_byte(i); |
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expect = __nvram_read_byte(PC_CKS_LOC)<<8 | |
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__nvram_read_byte(PC_CKS_LOC+1); |
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return (sum & 0xffff) == expect; |
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} |
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static void __nvram_set_checksum(void) |
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{ |
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int i; |
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unsigned short sum = 0; |
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for (i = PC_CKS_RANGE_START; i <= PC_CKS_RANGE_END; ++i) |
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sum += __nvram_read_byte(i); |
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__nvram_write_byte(sum >> 8, PC_CKS_LOC); |
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__nvram_write_byte(sum & 0xff, PC_CKS_LOC + 1); |
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} |
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static long pc_nvram_set_checksum(void) |
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{ |
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spin_lock_irq(&rtc_lock); |
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__nvram_set_checksum(); |
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spin_unlock_irq(&rtc_lock); |
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return 0; |
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} |
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static long pc_nvram_initialize(void) |
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{ |
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ssize_t i; |
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spin_lock_irq(&rtc_lock); |
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for (i = 0; i < NVRAM_BYTES; ++i) |
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__nvram_write_byte(0, i); |
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__nvram_set_checksum(); |
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spin_unlock_irq(&rtc_lock); |
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return 0; |
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} |
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static ssize_t pc_nvram_get_size(void) |
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{ |
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return NVRAM_BYTES; |
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} |
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static ssize_t pc_nvram_read(char *buf, size_t count, loff_t *ppos) |
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{ |
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char *p = buf; |
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loff_t i; |
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spin_lock_irq(&rtc_lock); |
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if (!__nvram_check_checksum()) { |
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spin_unlock_irq(&rtc_lock); |
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return -EIO; |
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} |
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for (i = *ppos; count > 0 && i < NVRAM_BYTES; --count, ++i, ++p) |
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*p = __nvram_read_byte(i); |
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spin_unlock_irq(&rtc_lock); |
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*ppos = i; |
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return p - buf; |
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} |
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static ssize_t pc_nvram_write(char *buf, size_t count, loff_t *ppos) |
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{ |
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char *p = buf; |
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loff_t i; |
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spin_lock_irq(&rtc_lock); |
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if (!__nvram_check_checksum()) { |
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spin_unlock_irq(&rtc_lock); |
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return -EIO; |
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} |
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for (i = *ppos; count > 0 && i < NVRAM_BYTES; --count, ++i, ++p) |
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__nvram_write_byte(*p, i); |
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__nvram_set_checksum(); |
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spin_unlock_irq(&rtc_lock); |
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*ppos = i; |
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return p - buf; |
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} |
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const struct nvram_ops arch_nvram_ops = { |
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.read = pc_nvram_read, |
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.write = pc_nvram_write, |
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.read_byte = pc_nvram_read_byte, |
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.write_byte = pc_nvram_write_byte, |
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.get_size = pc_nvram_get_size, |
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.set_checksum = pc_nvram_set_checksum, |
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.initialize = pc_nvram_initialize, |
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}; |
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EXPORT_SYMBOL(arch_nvram_ops); |
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#endif /* CONFIG_X86 */ |
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/* |
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* The are the file operation function for user access to /dev/nvram |
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*/ |
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static loff_t nvram_misc_llseek(struct file *file, loff_t offset, int origin) |
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{ |
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return generic_file_llseek_size(file, offset, origin, MAX_LFS_FILESIZE, |
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nvram_size); |
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} |
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static ssize_t nvram_misc_read(struct file *file, char __user *buf, |
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size_t count, loff_t *ppos) |
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{ |
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char *tmp; |
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ssize_t ret; |
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if (*ppos >= nvram_size) |
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return 0; |
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count = min_t(size_t, count, nvram_size - *ppos); |
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count = min_t(size_t, count, PAGE_SIZE); |
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tmp = kmalloc(count, GFP_KERNEL); |
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if (!tmp) |
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return -ENOMEM; |
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ret = nvram_read(tmp, count, ppos); |
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if (ret <= 0) |
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goto out; |
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if (copy_to_user(buf, tmp, ret)) { |
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*ppos -= ret; |
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ret = -EFAULT; |
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} |
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out: |
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kfree(tmp); |
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return ret; |
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} |
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static ssize_t nvram_misc_write(struct file *file, const char __user *buf, |
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size_t count, loff_t *ppos) |
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{ |
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char *tmp; |
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ssize_t ret; |
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if (*ppos >= nvram_size) |
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return 0; |
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count = min_t(size_t, count, nvram_size - *ppos); |
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count = min_t(size_t, count, PAGE_SIZE); |
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tmp = memdup_user(buf, count); |
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if (IS_ERR(tmp)) |
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return PTR_ERR(tmp); |
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ret = nvram_write(tmp, count, ppos); |
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kfree(tmp); |
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return ret; |
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} |
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static long nvram_misc_ioctl(struct file *file, unsigned int cmd, |
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unsigned long arg) |
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{ |
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long ret = -ENOTTY; |
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switch (cmd) { |
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#ifdef CONFIG_PPC |
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case OBSOLETE_PMAC_NVRAM_GET_OFFSET: |
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pr_warn("nvram: Using obsolete PMAC_NVRAM_GET_OFFSET ioctl\n"); |
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fallthrough; |
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case IOC_NVRAM_GET_OFFSET: |
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ret = -EINVAL; |
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#ifdef CONFIG_PPC_PMAC |
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if (machine_is(powermac)) { |
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int part, offset; |
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if (copy_from_user(&part, (void __user *)arg, |
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sizeof(part)) != 0) |
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return -EFAULT; |
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if (part < pmac_nvram_OF || part > pmac_nvram_NR) |
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return -EINVAL; |
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offset = pmac_get_partition(part); |
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if (offset < 0) |
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return -EINVAL; |
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if (copy_to_user((void __user *)arg, |
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&offset, sizeof(offset)) != 0) |
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return -EFAULT; |
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ret = 0; |
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} |
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#endif |
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break; |
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#ifdef CONFIG_PPC32 |
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case IOC_NVRAM_SYNC: |
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if (ppc_md.nvram_sync != NULL) { |
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mutex_lock(&nvram_mutex); |
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ppc_md.nvram_sync(); |
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mutex_unlock(&nvram_mutex); |
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} |
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ret = 0; |
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break; |
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#endif |
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#elif defined(CONFIG_X86) || defined(CONFIG_M68K) |
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case NVRAM_INIT: |
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/* initialize NVRAM contents and checksum */ |
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if (!capable(CAP_SYS_ADMIN)) |
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return -EACCES; |
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if (arch_nvram_ops.initialize != NULL) { |
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mutex_lock(&nvram_mutex); |
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ret = arch_nvram_ops.initialize(); |
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mutex_unlock(&nvram_mutex); |
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} |
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break; |
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case NVRAM_SETCKS: |
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/* just set checksum, contents unchanged (maybe useful after |
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* checksum garbaged somehow...) */ |
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if (!capable(CAP_SYS_ADMIN)) |
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return -EACCES; |
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if (arch_nvram_ops.set_checksum != NULL) { |
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mutex_lock(&nvram_mutex); |
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ret = arch_nvram_ops.set_checksum(); |
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mutex_unlock(&nvram_mutex); |
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} |
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break; |
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#endif /* CONFIG_X86 || CONFIG_M68K */ |
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} |
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return ret; |
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} |
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static int nvram_misc_open(struct inode *inode, struct file *file) |
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{ |
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spin_lock(&nvram_state_lock); |
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/* Prevent multiple readers/writers if desired. */ |
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if ((nvram_open_cnt && (file->f_flags & O_EXCL)) || |
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(nvram_open_mode & NVRAM_EXCL)) { |
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spin_unlock(&nvram_state_lock); |
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return -EBUSY; |
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} |
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#if defined(CONFIG_X86) || defined(CONFIG_M68K) |
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/* Prevent multiple writers if the set_checksum ioctl is implemented. */ |
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if ((arch_nvram_ops.set_checksum != NULL) && |
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(file->f_mode & FMODE_WRITE) && (nvram_open_mode & NVRAM_WRITE)) { |
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spin_unlock(&nvram_state_lock); |
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return -EBUSY; |
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} |
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#endif |
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if (file->f_flags & O_EXCL) |
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nvram_open_mode |= NVRAM_EXCL; |
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if (file->f_mode & FMODE_WRITE) |
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nvram_open_mode |= NVRAM_WRITE; |
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nvram_open_cnt++; |
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spin_unlock(&nvram_state_lock); |
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return 0; |
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} |
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static int nvram_misc_release(struct inode *inode, struct file *file) |
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{ |
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spin_lock(&nvram_state_lock); |
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nvram_open_cnt--; |
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/* if only one instance is open, clear the EXCL bit */ |
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if (nvram_open_mode & NVRAM_EXCL) |
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nvram_open_mode &= ~NVRAM_EXCL; |
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if (file->f_mode & FMODE_WRITE) |
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nvram_open_mode &= ~NVRAM_WRITE; |
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spin_unlock(&nvram_state_lock); |
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return 0; |
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} |
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#if defined(CONFIG_X86) && defined(CONFIG_PROC_FS) |
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static const char * const floppy_types[] = { |
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"none", "5.25'' 360k", "5.25'' 1.2M", "3.5'' 720k", "3.5'' 1.44M", |
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"3.5'' 2.88M", "3.5'' 2.88M" |
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}; |
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static const char * const gfx_types[] = { |
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"EGA, VGA, ... (with BIOS)", |
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"CGA (40 cols)", |
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"CGA (80 cols)", |
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"monochrome", |
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}; |
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static void pc_nvram_proc_read(unsigned char *nvram, struct seq_file *seq, |
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void *offset) |
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{ |
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int checksum; |
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int type; |
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spin_lock_irq(&rtc_lock); |
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checksum = __nvram_check_checksum(); |
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spin_unlock_irq(&rtc_lock); |
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seq_printf(seq, "Checksum status: %svalid\n", checksum ? "" : "not "); |
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seq_printf(seq, "# floppies : %d\n", |
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(nvram[6] & 1) ? (nvram[6] >> 6) + 1 : 0); |
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seq_printf(seq, "Floppy 0 type : "); |
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type = nvram[2] >> 4; |
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if (type < ARRAY_SIZE(floppy_types)) |
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seq_printf(seq, "%s\n", floppy_types[type]); |
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else |
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seq_printf(seq, "%d (unknown)\n", type); |
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seq_printf(seq, "Floppy 1 type : "); |
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type = nvram[2] & 0x0f; |
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if (type < ARRAY_SIZE(floppy_types)) |
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seq_printf(seq, "%s\n", floppy_types[type]); |
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else |
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seq_printf(seq, "%d (unknown)\n", type); |
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seq_printf(seq, "HD 0 type : "); |
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type = nvram[4] >> 4; |
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if (type) |
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seq_printf(seq, "%02x\n", type == 0x0f ? nvram[11] : type); |
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else |
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seq_printf(seq, "none\n"); |
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seq_printf(seq, "HD 1 type : "); |
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type = nvram[4] & 0x0f; |
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if (type) |
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seq_printf(seq, "%02x\n", type == 0x0f ? nvram[12] : type); |
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else |
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seq_printf(seq, "none\n"); |
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seq_printf(seq, "HD type 48 data: %d/%d/%d C/H/S, precomp %d, lz %d\n", |
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nvram[18] | (nvram[19] << 8), |
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nvram[20], nvram[25], |
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nvram[21] | (nvram[22] << 8), nvram[23] | (nvram[24] << 8)); |
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seq_printf(seq, "HD type 49 data: %d/%d/%d C/H/S, precomp %d, lz %d\n", |
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nvram[39] | (nvram[40] << 8), |
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nvram[41], nvram[46], |
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nvram[42] | (nvram[43] << 8), nvram[44] | (nvram[45] << 8)); |
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seq_printf(seq, "DOS base memory: %d kB\n", nvram[7] | (nvram[8] << 8)); |
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seq_printf(seq, "Extended memory: %d kB (configured), %d kB (tested)\n", |
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nvram[9] | (nvram[10] << 8), nvram[34] | (nvram[35] << 8)); |
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|
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seq_printf(seq, "Gfx adapter : %s\n", |
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gfx_types[(nvram[6] >> 4) & 3]); |
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seq_printf(seq, "FPU : %sinstalled\n", |
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(nvram[6] & 2) ? "" : "not "); |
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return; |
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} |
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static int nvram_proc_read(struct seq_file *seq, void *offset) |
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{ |
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unsigned char contents[NVRAM_BYTES]; |
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int i = 0; |
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spin_lock_irq(&rtc_lock); |
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for (i = 0; i < NVRAM_BYTES; ++i) |
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contents[i] = __nvram_read_byte(i); |
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spin_unlock_irq(&rtc_lock); |
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pc_nvram_proc_read(contents, seq, offset); |
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return 0; |
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} |
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#endif /* CONFIG_X86 && CONFIG_PROC_FS */ |
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|
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static const struct file_operations nvram_misc_fops = { |
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.owner = THIS_MODULE, |
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.llseek = nvram_misc_llseek, |
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.read = nvram_misc_read, |
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.write = nvram_misc_write, |
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.unlocked_ioctl = nvram_misc_ioctl, |
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.open = nvram_misc_open, |
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.release = nvram_misc_release, |
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}; |
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static struct miscdevice nvram_misc = { |
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NVRAM_MINOR, |
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"nvram", |
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&nvram_misc_fops, |
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}; |
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static int __init nvram_module_init(void) |
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{ |
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int ret; |
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nvram_size = nvram_get_size(); |
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if (nvram_size < 0) |
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return nvram_size; |
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ret = misc_register(&nvram_misc); |
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if (ret) { |
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pr_err("nvram: can't misc_register on minor=%d\n", NVRAM_MINOR); |
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return ret; |
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} |
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#if defined(CONFIG_X86) && defined(CONFIG_PROC_FS) |
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if (!proc_create_single("driver/nvram", 0, NULL, nvram_proc_read)) { |
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pr_err("nvram: can't create /proc/driver/nvram\n"); |
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misc_deregister(&nvram_misc); |
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return -ENOMEM; |
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} |
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#endif |
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|
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pr_info("Non-volatile memory driver v" NVRAM_VERSION "\n"); |
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return 0; |
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} |
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|
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static void __exit nvram_module_exit(void) |
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{ |
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#if defined(CONFIG_X86) && defined(CONFIG_PROC_FS) |
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remove_proc_entry("driver/nvram", NULL); |
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#endif |
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misc_deregister(&nvram_misc); |
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} |
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module_init(nvram_module_init); |
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module_exit(nvram_module_exit); |
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|
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MODULE_LICENSE("GPL"); |
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MODULE_ALIAS_MISCDEV(NVRAM_MINOR); |
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MODULE_ALIAS("devname:nvram");
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