diff options
Diffstat (limited to 'drivers/char/nvram.c')
| -rw-r--r-- | drivers/char/nvram.c | 545 |
1 files changed, 545 insertions, 0 deletions
diff --git a/drivers/char/nvram.c b/drivers/char/nvram.c new file mode 100644 index 000000000..e9f694b36 --- /dev/null +++ b/drivers/char/nvram.c @@ -0,0 +1,545 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * CMOS/NV-RAM driver for Linux + * + * Copyright (C) 1997 Roman Hodek <Roman.Hodek@informatik.uni-erlangen.de> + * idea by and with help from Richard Jelinek <rj@suse.de> + * Portions copyright (c) 2001,2002 Sun Microsystems (thockin@sun.com) + * + * This driver allows you to access the contents of the non-volatile memory in + * the mc146818rtc.h real-time clock. This chip is built into all PCs and into + * many Atari machines. In the former it's called "CMOS-RAM", in the latter + * "NVRAM" (NV stands for non-volatile). + * + * The data are supplied as a (seekable) character device, /dev/nvram. The + * size of this file is dependent on the controller. The usual size is 114, + * the number of freely available bytes in the memory (i.e., not used by the + * RTC itself). + * + * Checksums over the NVRAM contents are managed by this driver. In case of a + * bad checksum, reads and writes return -EIO. The checksum can be initialized + * to a sane state either by ioctl(NVRAM_INIT) (clear whole NVRAM) or + * ioctl(NVRAM_SETCKS) (doesn't change contents, just makes checksum valid + * again; use with care!) + * + * 1.1 Cesar Barros: SMP locking fixes + * added changelog + * 1.2 Erik Gilling: Cobalt Networks support + * Tim Hockin: general cleanup, Cobalt support + * 1.3 Wim Van Sebroeck: convert PRINT_PROC to seq_file + */ + +#define NVRAM_VERSION "1.3" + +#include <linux/module.h> +#include <linux/nvram.h> +#include <linux/types.h> +#include <linux/errno.h> +#include <linux/miscdevice.h> +#include <linux/ioport.h> +#include <linux/fcntl.h> +#include <linux/mc146818rtc.h> +#include <linux/init.h> +#include <linux/proc_fs.h> +#include <linux/seq_file.h> +#include <linux/slab.h> +#include <linux/spinlock.h> +#include <linux/io.h> +#include <linux/uaccess.h> +#include <linux/mutex.h> +#include <linux/pagemap.h> + +#ifdef CONFIG_PPC +#include <asm/nvram.h> +#endif + +static DEFINE_MUTEX(nvram_mutex); +static DEFINE_SPINLOCK(nvram_state_lock); +static int nvram_open_cnt; /* #times opened */ +static int nvram_open_mode; /* special open modes */ +static ssize_t nvram_size; +#define NVRAM_WRITE 1 /* opened for writing (exclusive) */ +#define NVRAM_EXCL 2 /* opened with O_EXCL */ + +#ifdef CONFIG_X86 +/* + * These functions are provided to be called internally or by other parts of + * the kernel. It's up to the caller to ensure correct checksum before reading + * or after writing (needs to be done only once). + * + * It is worth noting that these functions all access bytes of general + * purpose memory in the NVRAM - that is to say, they all add the + * NVRAM_FIRST_BYTE offset. Pass them offsets into NVRAM as if you did not + * know about the RTC cruft. + */ + +#define NVRAM_BYTES (128 - NVRAM_FIRST_BYTE) + +/* Note that *all* calls to CMOS_READ and CMOS_WRITE must be done with + * rtc_lock held. Due to the index-port/data-port design of the RTC, we + * don't want two different things trying to get to it at once. (e.g. the + * periodic 11 min sync from kernel/time/ntp.c vs. this driver.) + */ + +static unsigned char __nvram_read_byte(int i) +{ + return CMOS_READ(NVRAM_FIRST_BYTE + i); +} + +static unsigned char pc_nvram_read_byte(int i) +{ + unsigned long flags; + unsigned char c; + + spin_lock_irqsave(&rtc_lock, flags); + c = __nvram_read_byte(i); + spin_unlock_irqrestore(&rtc_lock, flags); + return c; +} + +/* This races nicely with trying to read with checksum checking (nvram_read) */ +static void __nvram_write_byte(unsigned char c, int i) +{ + CMOS_WRITE(c, NVRAM_FIRST_BYTE + i); +} + +static void pc_nvram_write_byte(unsigned char c, int i) +{ + unsigned long flags; + + spin_lock_irqsave(&rtc_lock, flags); + __nvram_write_byte(c, i); + spin_unlock_irqrestore(&rtc_lock, flags); +} + +/* On PCs, the checksum is built only over bytes 2..31 */ +#define PC_CKS_RANGE_START 2 +#define PC_CKS_RANGE_END 31 +#define PC_CKS_LOC 32 + +static int __nvram_check_checksum(void) +{ + int i; + unsigned short sum = 0; + unsigned short expect; + + for (i = PC_CKS_RANGE_START; i <= PC_CKS_RANGE_END; ++i) + sum += __nvram_read_byte(i); + expect = __nvram_read_byte(PC_CKS_LOC)<<8 | + __nvram_read_byte(PC_CKS_LOC+1); + return (sum & 0xffff) == expect; +} + +static void __nvram_set_checksum(void) +{ + int i; + unsigned short sum = 0; + + for (i = PC_CKS_RANGE_START; i <= PC_CKS_RANGE_END; ++i) + sum += __nvram_read_byte(i); + __nvram_write_byte(sum >> 8, PC_CKS_LOC); + __nvram_write_byte(sum & 0xff, PC_CKS_LOC + 1); +} + +static long pc_nvram_set_checksum(void) +{ + spin_lock_irq(&rtc_lock); + __nvram_set_checksum(); + spin_unlock_irq(&rtc_lock); + return 0; +} + +static long pc_nvram_initialize(void) +{ + ssize_t i; + + spin_lock_irq(&rtc_lock); + for (i = 0; i < NVRAM_BYTES; ++i) + __nvram_write_byte(0, i); + __nvram_set_checksum(); + spin_unlock_irq(&rtc_lock); + return 0; +} + +static ssize_t pc_nvram_get_size(void) +{ + return NVRAM_BYTES; +} + +static ssize_t pc_nvram_read(char *buf, size_t count, loff_t *ppos) +{ + char *p = buf; + loff_t i; + + spin_lock_irq(&rtc_lock); + if (!__nvram_check_checksum()) { + spin_unlock_irq(&rtc_lock); + return -EIO; + } + for (i = *ppos; count > 0 && i < NVRAM_BYTES; --count, ++i, ++p) + *p = __nvram_read_byte(i); + spin_unlock_irq(&rtc_lock); + + *ppos = i; + return p - buf; +} + +static ssize_t pc_nvram_write(char *buf, size_t count, loff_t *ppos) +{ + char *p = buf; + loff_t i; + + spin_lock_irq(&rtc_lock); + if (!__nvram_check_checksum()) { + spin_unlock_irq(&rtc_lock); + return -EIO; + } + for (i = *ppos; count > 0 && i < NVRAM_BYTES; --count, ++i, ++p) + __nvram_write_byte(*p, i); + __nvram_set_checksum(); + spin_unlock_irq(&rtc_lock); + + *ppos = i; + return p - buf; +} + +const struct nvram_ops arch_nvram_ops = { + .read = pc_nvram_read, + .write = pc_nvram_write, + .read_byte = pc_nvram_read_byte, + .write_byte = pc_nvram_write_byte, + .get_size = pc_nvram_get_size, + .set_checksum = pc_nvram_set_checksum, + .initialize = pc_nvram_initialize, +}; +EXPORT_SYMBOL(arch_nvram_ops); +#endif /* CONFIG_X86 */ + +/* + * The are the file operation function for user access to /dev/nvram + */ + +static loff_t nvram_misc_llseek(struct file *file, loff_t offset, int origin) +{ + return generic_file_llseek_size(file, offset, origin, MAX_LFS_FILESIZE, + nvram_size); +} + +static ssize_t nvram_misc_read(struct file *file, char __user *buf, + size_t count, loff_t *ppos) +{ + char *tmp; + ssize_t ret; + + + if (*ppos >= nvram_size) + return 0; + + count = min_t(size_t, count, nvram_size - *ppos); + count = min_t(size_t, count, PAGE_SIZE); + + tmp = kmalloc(count, GFP_KERNEL); + if (!tmp) + return -ENOMEM; + + ret = nvram_read(tmp, count, ppos); + if (ret <= 0) + goto out; + + if (copy_to_user(buf, tmp, ret)) { + *ppos -= ret; + ret = -EFAULT; + } + +out: + kfree(tmp); + return ret; +} + +static ssize_t nvram_misc_write(struct file *file, const char __user *buf, + size_t count, loff_t *ppos) +{ + char *tmp; + ssize_t ret; + + if (*ppos >= nvram_size) + return 0; + + count = min_t(size_t, count, nvram_size - *ppos); + count = min_t(size_t, count, PAGE_SIZE); + + tmp = memdup_user(buf, count); + if (IS_ERR(tmp)) + return PTR_ERR(tmp); + + ret = nvram_write(tmp, count, ppos); + kfree(tmp); + return ret; +} + +static long nvram_misc_ioctl(struct file *file, unsigned int cmd, + unsigned long arg) +{ + long ret = -ENOTTY; + + switch (cmd) { +#ifdef CONFIG_PPC + case OBSOLETE_PMAC_NVRAM_GET_OFFSET: + pr_warn("nvram: Using obsolete PMAC_NVRAM_GET_OFFSET ioctl\n"); + fallthrough; + case IOC_NVRAM_GET_OFFSET: + ret = -EINVAL; +#ifdef CONFIG_PPC_PMAC + if (machine_is(powermac)) { + int part, offset; + + if (copy_from_user(&part, (void __user *)arg, + sizeof(part)) != 0) + return -EFAULT; + if (part < pmac_nvram_OF || part > pmac_nvram_NR) + return -EINVAL; + offset = pmac_get_partition(part); + if (offset < 0) + return -EINVAL; + if (copy_to_user((void __user *)arg, + &offset, sizeof(offset)) != 0) + return -EFAULT; + ret = 0; + } +#endif + break; +#ifdef CONFIG_PPC32 + case IOC_NVRAM_SYNC: + if (ppc_md.nvram_sync != NULL) { + mutex_lock(&nvram_mutex); + ppc_md.nvram_sync(); + mutex_unlock(&nvram_mutex); + } + ret = 0; + break; +#endif +#elif defined(CONFIG_X86) || defined(CONFIG_M68K) + case NVRAM_INIT: + /* initialize NVRAM contents and checksum */ + if (!capable(CAP_SYS_ADMIN)) + return -EACCES; + + if (arch_nvram_ops.initialize != NULL) { + mutex_lock(&nvram_mutex); + ret = arch_nvram_ops.initialize(); + mutex_unlock(&nvram_mutex); + } + break; + case NVRAM_SETCKS: + /* just set checksum, contents unchanged (maybe useful after + * checksum garbaged somehow...) */ + if (!capable(CAP_SYS_ADMIN)) + return -EACCES; + + if (arch_nvram_ops.set_checksum != NULL) { + mutex_lock(&nvram_mutex); + ret = arch_nvram_ops.set_checksum(); + mutex_unlock(&nvram_mutex); + } + break; +#endif /* CONFIG_X86 || CONFIG_M68K */ + } + return ret; +} + +static int nvram_misc_open(struct inode *inode, struct file *file) +{ + spin_lock(&nvram_state_lock); + + /* Prevent multiple readers/writers if desired. */ + if ((nvram_open_cnt && (file->f_flags & O_EXCL)) || + (nvram_open_mode & NVRAM_EXCL)) { + spin_unlock(&nvram_state_lock); + return -EBUSY; + } + +#if defined(CONFIG_X86) || defined(CONFIG_M68K) + /* Prevent multiple writers if the set_checksum ioctl is implemented. */ + if ((arch_nvram_ops.set_checksum != NULL) && + (file->f_mode & FMODE_WRITE) && (nvram_open_mode & NVRAM_WRITE)) { + spin_unlock(&nvram_state_lock); + return -EBUSY; + } +#endif + + if (file->f_flags & O_EXCL) + nvram_open_mode |= NVRAM_EXCL; + if (file->f_mode & FMODE_WRITE) + nvram_open_mode |= NVRAM_WRITE; + nvram_open_cnt++; + + spin_unlock(&nvram_state_lock); + + return 0; +} + +static int nvram_misc_release(struct inode *inode, struct file *file) +{ + spin_lock(&nvram_state_lock); + + nvram_open_cnt--; + + /* if only one instance is open, clear the EXCL bit */ + if (nvram_open_mode & NVRAM_EXCL) + nvram_open_mode &= ~NVRAM_EXCL; + if (file->f_mode & FMODE_WRITE) + nvram_open_mode &= ~NVRAM_WRITE; + + spin_unlock(&nvram_state_lock); + + return 0; +} + +#if defined(CONFIG_X86) && defined(CONFIG_PROC_FS) +static const char * const floppy_types[] = { + "none", "5.25'' 360k", "5.25'' 1.2M", "3.5'' 720k", "3.5'' 1.44M", + "3.5'' 2.88M", "3.5'' 2.88M" +}; + +static const char * const gfx_types[] = { + "EGA, VGA, ... (with BIOS)", + "CGA (40 cols)", + "CGA (80 cols)", + "monochrome", +}; + +static void pc_nvram_proc_read(unsigned char *nvram, struct seq_file *seq, + void *offset) +{ + int checksum; + int type; + + spin_lock_irq(&rtc_lock); + checksum = __nvram_check_checksum(); + spin_unlock_irq(&rtc_lock); + + seq_printf(seq, "Checksum status: %svalid\n", checksum ? "" : "not "); + + seq_printf(seq, "# floppies : %d\n", + (nvram[6] & 1) ? (nvram[6] >> 6) + 1 : 0); + seq_printf(seq, "Floppy 0 type : "); + type = nvram[2] >> 4; + if (type < ARRAY_SIZE(floppy_types)) + seq_printf(seq, "%s\n", floppy_types[type]); + else + seq_printf(seq, "%d (unknown)\n", type); + seq_printf(seq, "Floppy 1 type : "); + type = nvram[2] & 0x0f; + if (type < ARRAY_SIZE(floppy_types)) + seq_printf(seq, "%s\n", floppy_types[type]); + else + seq_printf(seq, "%d (unknown)\n", type); + + seq_printf(seq, "HD 0 type : "); + type = nvram[4] >> 4; + if (type) + seq_printf(seq, "%02x\n", type == 0x0f ? nvram[11] : type); + else + seq_printf(seq, "none\n"); + + seq_printf(seq, "HD 1 type : "); + type = nvram[4] & 0x0f; + if (type) + seq_printf(seq, "%02x\n", type == 0x0f ? nvram[12] : type); + else + seq_printf(seq, "none\n"); + + seq_printf(seq, "HD type 48 data: %d/%d/%d C/H/S, precomp %d, lz %d\n", + nvram[18] | (nvram[19] << 8), + nvram[20], nvram[25], + nvram[21] | (nvram[22] << 8), nvram[23] | (nvram[24] << 8)); + seq_printf(seq, "HD type 49 data: %d/%d/%d C/H/S, precomp %d, lz %d\n", + nvram[39] | (nvram[40] << 8), + nvram[41], nvram[46], + nvram[42] | (nvram[43] << 8), nvram[44] | (nvram[45] << 8)); + + seq_printf(seq, "DOS base memory: %d kB\n", nvram[7] | (nvram[8] << 8)); + seq_printf(seq, "Extended memory: %d kB (configured), %d kB (tested)\n", + nvram[9] | (nvram[10] << 8), nvram[34] | (nvram[35] << 8)); + + seq_printf(seq, "Gfx adapter : %s\n", + gfx_types[(nvram[6] >> 4) & 3]); + + seq_printf(seq, "FPU : %sinstalled\n", + (nvram[6] & 2) ? "" : "not "); + + return; +} + +static int nvram_proc_read(struct seq_file *seq, void *offset) +{ + unsigned char contents[NVRAM_BYTES]; + int i = 0; + + spin_lock_irq(&rtc_lock); + for (i = 0; i < NVRAM_BYTES; ++i) + contents[i] = __nvram_read_byte(i); + spin_unlock_irq(&rtc_lock); + + pc_nvram_proc_read(contents, seq, offset); + + return 0; +} +#endif /* CONFIG_X86 && CONFIG_PROC_FS */ + +static const struct file_operations nvram_misc_fops = { + .owner = THIS_MODULE, + .llseek = nvram_misc_llseek, + .read = nvram_misc_read, + .write = nvram_misc_write, + .unlocked_ioctl = nvram_misc_ioctl, + .open = nvram_misc_open, + .release = nvram_misc_release, +}; + +static struct miscdevice nvram_misc = { + NVRAM_MINOR, + "nvram", + &nvram_misc_fops, +}; + +static int __init nvram_module_init(void) +{ + int ret; + + nvram_size = nvram_get_size(); + if (nvram_size < 0) + return nvram_size; + + ret = misc_register(&nvram_misc); + if (ret) { + pr_err("nvram: can't misc_register on minor=%d\n", NVRAM_MINOR); + return ret; + } + +#if defined(CONFIG_X86) && defined(CONFIG_PROC_FS) + if (!proc_create_single("driver/nvram", 0, NULL, nvram_proc_read)) { + pr_err("nvram: can't create /proc/driver/nvram\n"); + misc_deregister(&nvram_misc); + return -ENOMEM; + } +#endif + + pr_info("Non-volatile memory driver v" NVRAM_VERSION "\n"); + return 0; +} + +static void __exit nvram_module_exit(void) +{ +#if defined(CONFIG_X86) && defined(CONFIG_PROC_FS) + remove_proc_entry("driver/nvram", NULL); +#endif + misc_deregister(&nvram_misc); +} + +module_init(nvram_module_init); +module_exit(nvram_module_exit); + +MODULE_LICENSE("GPL"); +MODULE_ALIAS_MISCDEV(NVRAM_MINOR); +MODULE_ALIAS("devname:nvram"); |