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authorRobert Lippert <rlippert@google.com>2018-07-06 21:25:32 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-07-16 14:30:47 +0300
commit3772e5da445420543b25825ac2b5971f3743f6e8 (patch)
tree8386abef3013272a1e5ac78ca4a5cd36102c830b /drivers/misc
parent7f3838fb8c03d8ef52792ac3654a0b5f79a673e5 (diff)
downloadlinux-3772e5da445420543b25825ac2b5971f3743f6e8.tar.xz
drivers/misc: Aspeed LPC snoop output using misc chardev
Provides the data bytes snooped over the LPC snoop bus to userspace as a (blocking) misc character device. Bytes output from the host using LPC I/O transactions to the snooped port can be watched or retrieved from the character device using a simple command like this: ~# od -w1 -A n -t x1 /dev/aspeed-lpc-snoop0 10 de ad c0 ff ee Signed-off-by: Robert Lippert <rlippert@google.com> Signed-off-by: Patrick Venture <venture@google.com> Signed-off-by: Benjamin Fair <benjaminfair@google.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/misc')
-rw-r--r--drivers/misc/aspeed-lpc-snoop.c84
1 files changed, 74 insertions, 10 deletions
diff --git a/drivers/misc/aspeed-lpc-snoop.c b/drivers/misc/aspeed-lpc-snoop.c
index cb78c98bc78d..2feb4347d67f 100644
--- a/drivers/misc/aspeed-lpc-snoop.c
+++ b/drivers/misc/aspeed-lpc-snoop.c
@@ -16,12 +16,15 @@
#include <linux/bitops.h>
#include <linux/interrupt.h>
+#include <linux/fs.h>
#include <linux/kfifo.h>
#include <linux/mfd/syscon.h>
+#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
+#include <linux/poll.h>
#include <linux/regmap.h>
#define DEVICE_NAME "aspeed-lpc-snoop"
@@ -59,20 +62,70 @@ struct aspeed_lpc_snoop_model_data {
unsigned int has_hicrb_ensnp;
};
+struct aspeed_lpc_snoop_channel {
+ struct kfifo fifo;
+ wait_queue_head_t wq;
+ struct miscdevice miscdev;
+};
+
struct aspeed_lpc_snoop {
struct regmap *regmap;
int irq;
- struct kfifo snoop_fifo[NUM_SNOOP_CHANNELS];
+ struct aspeed_lpc_snoop_channel chan[NUM_SNOOP_CHANNELS];
+};
+
+static struct aspeed_lpc_snoop_channel *snoop_file_to_chan(struct file *file)
+{
+ return container_of(file->private_data,
+ struct aspeed_lpc_snoop_channel,
+ miscdev);
+}
+
+static ssize_t snoop_file_read(struct file *file, char __user *buffer,
+ size_t count, loff_t *ppos)
+{
+ struct aspeed_lpc_snoop_channel *chan = snoop_file_to_chan(file);
+ unsigned int copied;
+ int ret = 0;
+
+ if (kfifo_is_empty(&chan->fifo)) {
+ if (file->f_flags & O_NONBLOCK)
+ return -EAGAIN;
+ ret = wait_event_interruptible(chan->wq,
+ !kfifo_is_empty(&chan->fifo));
+ if (ret == -ERESTARTSYS)
+ return -EINTR;
+ }
+ ret = kfifo_to_user(&chan->fifo, buffer, count, &copied);
+
+ return ret ? ret : copied;
+}
+
+static unsigned int snoop_file_poll(struct file *file,
+ struct poll_table_struct *pt)
+{
+ struct aspeed_lpc_snoop_channel *chan = snoop_file_to_chan(file);
+
+ poll_wait(file, &chan->wq, pt);
+ return !kfifo_is_empty(&chan->fifo) ? POLLIN : 0;
+}
+
+static const struct file_operations snoop_fops = {
+ .owner = THIS_MODULE,
+ .read = snoop_file_read,
+ .poll = snoop_file_poll,
+ .llseek = noop_llseek,
};
/* Save a byte to a FIFO and discard the oldest byte if FIFO is full */
-static void put_fifo_with_discard(struct kfifo *fifo, u8 val)
+static void put_fifo_with_discard(struct aspeed_lpc_snoop_channel *chan, u8 val)
{
- if (!kfifo_initialized(fifo))
+ if (!kfifo_initialized(&chan->fifo))
return;
- if (kfifo_is_full(fifo))
- kfifo_skip(fifo);
- kfifo_put(fifo, val);
+ if (kfifo_is_full(&chan->fifo))
+ kfifo_skip(&chan->fifo);
+ kfifo_put(&chan->fifo, val);
+ wake_up_interruptible(&chan->wq);
}
static irqreturn_t aspeed_lpc_snoop_irq(int irq, void *arg)
@@ -97,12 +150,12 @@ static irqreturn_t aspeed_lpc_snoop_irq(int irq, void *arg)
if (reg & HICR6_STR_SNP0W) {
u8 val = (data & SNPWDR_CH0_MASK) >> SNPWDR_CH0_SHIFT;
- put_fifo_with_discard(&lpc_snoop->snoop_fifo[0], val);
+ put_fifo_with_discard(&lpc_snoop->chan[0], val);
}
if (reg & HICR6_STR_SNP1W) {
u8 val = (data & SNPWDR_CH1_MASK) >> SNPWDR_CH1_SHIFT;
- put_fifo_with_discard(&lpc_snoop->snoop_fifo[1], val);
+ put_fifo_with_discard(&lpc_snoop->chan[1], val);
}
return IRQ_HANDLED;
@@ -139,12 +192,22 @@ static int aspeed_lpc_enable_snoop(struct aspeed_lpc_snoop *lpc_snoop,
const struct aspeed_lpc_snoop_model_data *model_data =
of_device_get_match_data(dev);
+ init_waitqueue_head(&lpc_snoop->chan[channel].wq);
/* Create FIFO datastructure */
- rc = kfifo_alloc(&lpc_snoop->snoop_fifo[channel],
+ rc = kfifo_alloc(&lpc_snoop->chan[channel].fifo,
SNOOP_FIFO_SIZE, GFP_KERNEL);
if (rc)
return rc;
+ lpc_snoop->chan[channel].miscdev.minor = MISC_DYNAMIC_MINOR;
+ lpc_snoop->chan[channel].miscdev.name =
+ devm_kasprintf(dev, GFP_KERNEL, "%s%d", DEVICE_NAME, channel);
+ lpc_snoop->chan[channel].miscdev.fops = &snoop_fops;
+ lpc_snoop->chan[channel].miscdev.parent = dev;
+ rc = misc_register(&lpc_snoop->chan[channel].miscdev);
+ if (rc)
+ return rc;
+
/* Enable LPC snoop channel at requested port */
switch (channel) {
case 0:
@@ -191,7 +254,8 @@ static void aspeed_lpc_disable_snoop(struct aspeed_lpc_snoop *lpc_snoop,
return;
}
- kfifo_free(&lpc_snoop->snoop_fifo[channel]);
+ kfifo_free(&lpc_snoop->chan[channel].fifo);
+ misc_deregister(&lpc_snoop->chan[channel].miscdev);
}
static int aspeed_lpc_snoop_probe(struct platform_device *pdev)