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Message-Id: <1328623901-20628-1-git-send-email-ajax@redhat.com>
Date: Tue, 7 Feb 2012 09:11:40 -0500
From: Adam Jackson <ajax@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: arnd@...db.de, gregkh@...uxfoundation.org
Subject: [PATCH 1/2] char/mem: Add /dev/io
This is like /dev/port except not broken. /dev/port will translate all
read/write into inb/outb streams, which is wrong since hardware can and
does care about cycle size. /dev/io will only allow 1, 2, or 4 byte
access, and will translate that into the appropriate bus cycle size.
Signed-off-by: Adam Jackson <ajax@...hat.com>
---
drivers/char/mem.c | 92 ++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 92 insertions(+), 0 deletions(-)
diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index d6e9d08..276b0e5 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -611,6 +611,88 @@ static ssize_t write_port(struct file *file, const char __user *buf,
*ppos = i;
return tmp-buf;
}
+
+static ssize_t read_io(struct file *file, char __user *buf, size_t count,
+ loff_t *ppos)
+{
+ unsigned long port = *ppos;
+ const char __user * tmp = buf;
+
+ switch (count) {
+ case 1:
+ case 2:
+ case 4:
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ if (!access_ok(VERIFY_WRITE, buf, count))
+ return -EFAULT;
+
+ switch (count) {
+ case 1:
+ if (__put_user(inb(port), tmp) < 0)
+ return -EFAULT;
+ break;
+ case 2:
+ if (__put_user(inw(port), tmp) < 0)
+ return -EFAULT;
+ break;
+ case 4:
+ if (__put_user(inl(port), tmp) < 0)
+ return -EFAULT;
+ break;
+ }
+
+ *ppos += count;
+ return count;
+}
+
+static ssize_t write_io(struct file *file, const char __user *buf, size_t count,
+ loff_t *ppos)
+{
+ unsigned long port = *ppos;
+ const char __user * tmp = buf;
+ u8 byte;
+ u16 word;
+ u32 dword;
+
+ switch (count) {
+ case 1:
+ case 2:
+ case 4:
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ if (!access_ok(VERIFY_READ, buf, count))
+ return -EFAULT;
+
+ switch (count) {
+ case 1:
+ if (__get_user(byte, tmp))
+ return -EFAULT;
+ outb(byte, port);
+ break;
+ case 2:
+ if (__get_user(word, tmp))
+ return -EFAULT;
+ outw(word, port);
+ break;
+ case 4:
+ if (__get_user(dword, tmp))
+ return -EFAULT;
+ outl(dword, port);
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ *ppos += count;
+ return count;
+}
#endif
static ssize_t read_null(struct file *file, char __user *buf,
@@ -774,6 +856,13 @@ static const struct file_operations port_fops = {
.write = write_port,
.open = open_port,
};
+
+static const struct file_operations io_fops = {
+ .llseek = memory_lseek,
+ .read = read_io,
+ .write = write_io,
+ .open = open_port,
+};
#endif
static const struct file_operations zero_fops = {
@@ -867,6 +956,9 @@ static const struct memdev {
#ifdef CONFIG_CRASH_DUMP
[12] = { "oldmem", 0, &oldmem_fops, NULL },
#endif
+#ifdef CONFIG_DEVPORT
+ [13] = { "io", 0, &io_fops, NULL },
+#endif
};
static int memory_open(struct inode *inode, struct file *filp)
--
1.7.7.6
--
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