From: Finn Thain <fthain@telegraphics.com.au>
To: <linux-kernel@vger.kernel.org>, <linux-m68k@vger.kernel.org>,
<linuxppc-dev@lists.ozlabs.org>, Arnd Bergmann <arnd@arndb.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: [PATCH v7 08/26] char/nvram: Implement NVRAM read/write methods
Date: Sun, 01 Nov 2015 21:42:10 +1100 [thread overview]
Message-ID: <20151101104204.301733351@telegraphics.com.au> (raw)
In-Reply-To: 20151101104202.301856132@telegraphics.com.au
[-- Attachment #1: nvram-generalize-read-write --]
[-- Type: text/plain, Size: 5677 bytes --]
Refactor the RTC "CMOS" NVRAM functions so that they can be used as
arch_nvram_ops methods. Checksumming logic is moved from the misc device
operations to the nvram read/write operations.
This makes the misc device implementation more generic. This also
preserves the locking semantics such that "read if checksum valid" and
"write and update checksum" remain atomic operations.
PPC64 implements byte-range read/write methods which are similar to
file_operations struct methods. Other platforms provide only
byte-at-a-time functions. So the misc device prefers the former but
will fall back on the latter.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
---
drivers/char/nvram.c | 162 +++++++++++++++++++++++++++++++++++----------------
1 file changed, 114 insertions(+), 48 deletions(-)
Index: linux/drivers/char/nvram.c
===================================================================
--- linux.orig/drivers/char/nvram.c 2015-11-01 21:41:32.000000000 +1100
+++ linux/drivers/char/nvram.c 2015-11-01 21:41:34.000000000 +1100
@@ -41,6 +41,7 @@
#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>
@@ -178,9 +179,48 @@ static ssize_t nvram_get_size(void)
return NVRAM_BYTES;
}
+static ssize_t 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 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_byte = nvram_read_byte,
.write_byte = nvram_write_byte,
+ .read = nvram_read,
+ .write = nvram_write,
.get_size = nvram_get_size,
.set_checksum = nvram_set_checksum,
.initialize = nvram_initialize,
@@ -215,69 +255,95 @@ static loff_t nvram_misc_llseek(struct f
static ssize_t nvram_misc_read(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
- unsigned char contents[NVRAM_BYTES];
- unsigned i = *ppos;
- unsigned char *tmp;
-
- spin_lock_irq(&rtc_lock);
+ loff_t i;
+ char __user *p = buf;
- if (!__nvram_check_checksum())
- goto checksum_err;
-
- for (tmp = contents; count-- > 0 && i < NVRAM_BYTES; ++i, ++tmp)
- *tmp = __nvram_read_byte(i);
-
- spin_unlock_irq(&rtc_lock);
-
- if (copy_to_user(buf, contents, tmp - contents))
+ if (!access_ok(VERIFY_WRITE, buf, count))
return -EFAULT;
+ if (*ppos >= nvram_size)
+ return 0;
- *ppos = i;
-
- return tmp - contents;
+ /* If the arch provided a byte range read op, use it. Otherwise
+ * fall back on the byte-at-a-time accessor.
+ */
+ if (arch_nvram_ops.read != NULL) {
+ char *tmp;
+ ssize_t ret;
+
+ 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 = arch_nvram_ops.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;
+ }
-checksum_err:
- spin_unlock_irq(&rtc_lock);
- return -EIO;
+ for (i = *ppos; count > 0 && i < nvram_size; ++i, ++p, --count)
+ if (__put_user(arch_nvram_ops.read_byte(i), p))
+ return -EFAULT;
+ *ppos = i;
+ return p - buf;
}
static ssize_t nvram_misc_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
- unsigned char contents[NVRAM_BYTES];
- unsigned i = *ppos;
- unsigned char *tmp;
-
- if (i >= NVRAM_BYTES)
- return 0; /* Past EOF */
-
- if (count > NVRAM_BYTES - i)
- count = NVRAM_BYTES - i;
- if (count > NVRAM_BYTES)
- return -EFAULT; /* Can't happen, but prove it to gcc */
+ loff_t i;
+ const char __user *p = buf;
- if (copy_from_user(contents, buf, count))
+ if (!access_ok(VERIFY_READ, buf, count))
return -EFAULT;
+ if (*ppos >= nvram_size)
+ return 0;
- spin_lock_irq(&rtc_lock);
-
- if (!__nvram_check_checksum())
- goto checksum_err;
-
- for (tmp = contents; count--; ++i, ++tmp)
- __nvram_write_byte(*tmp, i);
-
- __nvram_set_checksum();
+ /* If the arch provided a byte range write op, use it. Otherwise
+ * fall back on the byte-at-a-time accessor.
+ */
+ if (arch_nvram_ops.write != NULL) {
+ char *tmp;
+ ssize_t ret;
+
+ 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;
+
+ if (copy_from_user(tmp, buf, count)) {
+ ret = -EFAULT;
+ goto out;
+ }
+
+ ret = arch_nvram_ops.write(tmp, count, ppos);
+
+out:
+ kfree(tmp);
+ return ret;
+ }
- spin_unlock_irq(&rtc_lock);
+ for (i = *ppos; count > 0 && i < nvram_size; ++i, ++p, --count) {
+ char c;
+ if (__get_user(c, p))
+ return -EFAULT;
+ arch_nvram_ops.write_byte(c, i);
+ }
*ppos = i;
-
- return tmp - contents;
-
-checksum_err:
- spin_unlock_irq(&rtc_lock);
- return -EIO;
+ return p - buf;
}
static long nvram_misc_ioctl(struct file *file, unsigned int cmd,
next prev parent reply other threads:[~2015-11-01 10:52 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-01 10:42 [PATCH v7 00/26] Re-use nvram module Finn Thain
2015-11-01 10:42 ` [PATCH v7 01/26] scsi/atari_scsi: Dont select CONFIG_NVRAM Finn Thain
2015-11-01 10:42 ` [PATCH v7 02/26] m68k/atari: Move Atari-specific code out of drivers/char/nvram.c Finn Thain
2015-11-01 10:42 ` [PATCH v7 03/26] m68k/atari: Replace nvram_{read,write}_byte with arch_nvram_ops Finn Thain
2015-11-01 10:42 ` [PATCH v7 04/26] char/nvram: Re-order functions to remove forward declarations and #ifdefs Finn Thain
2015-11-01 10:42 ` [PATCH v7 05/26] char/nvram: Adopt arch_nvram_ops Finn Thain
2015-11-01 10:42 ` [PATCH v7 06/26] x86/thinkpad_acpi: Use arch_nvram_ops methods instead of nvram_read_byte() and nvram_write_byte() Finn Thain
2015-11-01 10:42 ` [PATCH v7 07/26] char/nvram: Allow the set_checksum and initialize ioctls to be omitted Finn Thain
2015-11-01 10:42 ` Finn Thain [this message]
2015-11-01 10:42 ` [PATCH v7 09/26] char/nvram: Use generic fixed_size_llseek() Finn Thain
2015-11-01 10:42 ` [PATCH v7 10/26] m68k/atari: Implement arch_nvram_ops methods and enable CONFIG_HAVE_ARCH_NVRAM_OPS Finn Thain
2015-11-01 10:42 ` [PATCH v7 11/26] char/nvram: Add "devname:nvram" module alias Finn Thain
2015-11-01 10:42 ` [PATCH v7 12/26] powerpc: Cleanup nvram includes Finn Thain
2015-11-01 10:42 ` [PATCH v7 13/26] powerpc: Add missing ppc_md.nvram_size for CHRP and PowerMac Finn Thain
2015-11-01 10:42 ` [PATCH v7 14/26] powerpc: Implement arch_nvram_ops.get_size() and remove old nvram_* exports Finn Thain
2015-11-01 10:42 ` [PATCH v7 15/26] powerpc: Implement nvram sync ioctl Finn Thain
2015-11-01 10:42 ` [PATCH v7 16/26] powerpc, fbdev: Use NV_CMODE and NV_VMODE only when CONFIG_PPC32 and CONFIG_PPC_PMAC and CONFIG_NVRAM Finn Thain
2015-11-01 10:42 ` [PATCH v7 17/26] powerpc, fbdev: Use arch_nvram_ops methods instead of nvram_read_byte() and nvram_write_byte() Finn Thain
2015-11-01 10:42 ` [PATCH v7 18/26] nvram: Drop nvram_* symbol exports and prototypes Finn Thain
2015-11-01 10:42 ` [PATCH v7 19/26] powerpc: Remove CONFIG_GENERIC_NVRAM and adopt CONFIG_HAVE_ARCH_NVRAM_OPS Finn Thain
2015-11-01 10:42 ` [PATCH v7 20/26] char/generic_nvram: Remove as unused Finn Thain
2015-11-01 10:42 ` [PATCH v7 21/26] powerpc: Adopt nvram module for PPC64 Finn Thain
2015-11-01 10:42 ` [PATCH v7 22/26] powerpc: Remove pmac_xpram_{read,write} functions Finn Thain
2015-11-01 10:42 ` [PATCH v7 23/26] m68k/mac: Adopt naming and calling conventions for PRAM routines Finn Thain
2015-11-01 10:42 ` [PATCH v7 24/26] m68k/mac: Use macros for RTC accesses not magic numbers Finn Thain
2015-11-01 10:42 ` [PATCH v7 25/26] m68k/mac: Fix PRAM accessors Finn Thain
2015-11-01 10:42 ` [PATCH v7 26/26] m68k: Dispatch nvram_ops calls to Atari or Mac functions Finn Thain
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