Enabling interrupt based mailbox

Modifying the mailbox driver to use FIFO queue while using interrupt.

Signed-off-by: Arun P. Mohanan <arun.p.m@linux.intel.com>

1 files changed, 69 insertions, 33 deletions

diff --git a/drivers/soc/aspeed/aspeed-lpc-mbox.c b/drivers/soc/aspeed/aspeed-lpc-mbox.c
index 5e45777c13ac..1ae26604a596 100644
--- a/drivers/soc/aspeed/aspeed-lpc-mbox.c
+++ b/drivers/soc/aspeed/aspeed-lpc-mbox.c
@@ -12,10 +12,11 @@
 #include <linux/poll.h>
 #include <linux/regmap.h>
 #include <linux/slab.h>
+#include <linux/kfifo.h>
 
 #define DEVICE_NAME	"aspeed-mbox"
 
-#define MBX_USE_INTERRUPT 0
+#define MBX_USE_INTERRUPT 1
 
 #define ASPEED_MBOX_NUM_REGS 16
 
@@ -29,6 +30,7 @@
 #define ASPEED_MBOX_HOST_CTRL 0x4c
 #define ASPEED_MBOX_INTERRUPT_0 0x50
 #define ASPEED_MBOX_INTERRUPT_1 0x54
+#define MBOX_FIFO_SIZE 64
 
 struct aspeed_mbox {
 	struct miscdevice	miscdev;
@@ -38,6 +40,8 @@ struct aspeed_mbox {
 	int			irq;
 	wait_queue_head_t	queue;
 	struct mutex		mutex;
+	struct kfifo		fifo;
+	spinlock_t			lock;
 };
 
 static atomic_t aspeed_mbox_open_count = ATOMIC_INIT(0);
@@ -74,20 +78,37 @@ static struct aspeed_mbox *file_mbox(struct file *file)
 	return container_of(file->private_data, struct aspeed_mbox, miscdev);
 }
 
+/* Save a byte to a FIFO and discard the oldest byte if FIFO is full */
+static void put_fifo_with_discard(struct aspeed_mbox *mbox, u8 val)
+{
+	if (!kfifo_initialized(&mbox->fifo))
+		return;
+	if (kfifo_is_full(&mbox->fifo))
+		kfifo_skip(&mbox->fifo);
+	kfifo_put(&mbox->fifo, val);
+}
+
 static int aspeed_mbox_open(struct inode *inode, struct file *file)
 {
 #if MBX_USE_INTERRUPT
 	struct aspeed_mbox *mbox = file_mbox(file);
+	int i;
 #endif
 
 	if (atomic_inc_return(&aspeed_mbox_open_count) == 1) {
 #if MBX_USE_INTERRUPT
 		/*
-		 * Clear the interrupt status bit if it was left on and unmask
-		 * interrupts.
-		 * ASPEED_MBOX_CTRL_RECV bit is W1C, this also unmasks in 1 step
+		 * Reset the FIFO while opening to clear the old cached data
+		 * and load the FIFO with latest mailbox register values.
 		 */
-		aspeed_mbox_outb(mbox, ASPEED_MBOX_CTRL_RECV, ASPEED_MBOX_BMC_CTRL);
+		kfifo_reset(&mbox->fifo);
+		spin_lock_irq(&mbox->lock);
+		for (i = 0; i < ASPEED_MBOX_NUM_REGS; i++) {
+			put_fifo_with_discard(mbox,
+					aspeed_mbox_inb(mbox, ASPEED_MBOX_DATA_0 + (i * 4)));
+		}
+		spin_unlock_irq(&mbox->lock);
+
 #endif
 		return 0;
 	}
@@ -102,6 +123,8 @@ static ssize_t aspeed_mbox_read(struct file *file, char __user *buf,
 	struct aspeed_mbox *mbox = file_mbox(file);
 	char __user *p = buf;
 	ssize_t ret;
+	unsigned int copied;
+	unsigned long flags;
 	int i;
 
 	if (!access_ok(buf, count))
@@ -111,17 +134,32 @@ static ssize_t aspeed_mbox_read(struct file *file, char __user *buf,
 		return -EINVAL;
 
 #if MBX_USE_INTERRUPT
-	if (file->f_flags & O_NONBLOCK) {
-		if (!(aspeed_mbox_inb(mbox, ASPEED_MBOX_BMC_CTRL) &
-				ASPEED_MBOX_CTRL_RECV))
+	/*
+	 * Restrict count as per the number of mailbox registers
+	 * to use kfifo.
+	 */
+	if (count != ASPEED_MBOX_NUM_REGS)
+		goto reg_read;
+
+	if (kfifo_is_empty(&mbox->fifo)) {
+		if (file->f_flags & O_NONBLOCK){
 			return -EAGAIN;
-	} else if (wait_event_interruptible(mbox->queue,
-				aspeed_mbox_inb(mbox, ASPEED_MBOX_BMC_CTRL) &
-				ASPEED_MBOX_CTRL_RECV)) {
-		return -ERESTARTSYS;
+			}
+		ret = wait_event_interruptible(mbox->queue,
+				!kfifo_is_empty(&mbox->fifo));
+		if (ret == -ERESTARTSYS){
+			return -EINTR;
+			}
 	}
+
+	spin_lock_irqsave(&mbox->lock, flags);
+	ret = kfifo_to_user(&mbox->fifo, buf, count, &copied);
+	spin_unlock_irqrestore(&mbox->lock, flags);
+	return ret ? ret : copied;
+
 #endif
 
+reg_read:
 	mutex_lock(&mbox->mutex);
 
 	for (i = *ppos; count > 0 && i < ASPEED_MBOX_NUM_REGS; i++) {
@@ -134,11 +172,6 @@ static ssize_t aspeed_mbox_read(struct file *file, char __user *buf,
 		p++;
 		count--;
 	}
-
-#if MBX_USE_INTERRUPT
-	/* ASPEED_MBOX_CTRL_RECV bit is write to clear, this also unmasks in 1 step */
-	aspeed_mbox_outb(mbox, ASPEED_MBOX_CTRL_RECV, ASPEED_MBOX_BMC_CTRL);
-#endif
 	ret = p - buf;
 
 out_unlock:
@@ -186,16 +219,9 @@ out_unlock:
 static unsigned int aspeed_mbox_poll(struct file *file, poll_table *wait)
 {
 	struct aspeed_mbox *mbox = file_mbox(file);
-	unsigned int mask = 0;
 
 	poll_wait(file, &mbox->queue, wait);
-
-#if MBX_USE_INTERRUPT
-	if (aspeed_mbox_inb(mbox, ASPEED_MBOX_BMC_CTRL) & ASPEED_MBOX_CTRL_RECV)
-#endif
-		mask |= POLLIN;
-
-	return mask;
+	return !kfifo_is_empty(&mbox->fifo) ? POLLIN : 0;
 }
 
 static int aspeed_mbox_release(struct inode *inode, struct file *file)
@@ -220,19 +246,23 @@ static irqreturn_t aspeed_mbox_irq(int irq, void *arg)
 #if MBX_USE_INTERRUPT
 	int i;
 
-//	if (!(aspeed_mbox_inb(mbox, ASPEED_MBOX_BMC_CTRL) & ASPEED_MBOX_CTRL_RECV))
-//		return IRQ_NONE;
-
-	printk(KERN_ERR "BMC_CTRL: 0x%02x\n",
+	dev_dbg(mbox->miscdev.parent, "BMC_CTRL11: 0x%02x\n",
 	       aspeed_mbox_inb(mbox, ASPEED_MBOX_BMC_CTRL));
-	printk(KERN_ERR "STATUS_0: 0x%02x\n",
+	dev_dbg(mbox->miscdev.parent, "STATUS_0: 0x%02x\n",
 	       aspeed_mbox_inb(mbox, ASPEED_MBOX_STATUS_0));
-	printk(KERN_ERR "STATUS_1: 0x%02x\n",
+	dev_dbg(mbox->miscdev.parent, "STATUS_1: 0x%02x\n",
 	       aspeed_mbox_inb(mbox, ASPEED_MBOX_STATUS_1));
 	for (i = 0; i < ASPEED_MBOX_NUM_REGS; i++) {
-		printk(KERN_ERR "DATA_%d: 0x%02x\n", i,
+		dev_dbg(mbox->miscdev.parent, "DATA_%d: 0x%02x\n", i,
 		       aspeed_mbox_inb(mbox, ASPEED_MBOX_DATA_0 + (i * 4)));
 	}
+
+	spin_lock(&mbox->lock);
+	for (i = 0; i < ASPEED_MBOX_NUM_REGS; i++) {
+		put_fifo_with_discard(mbox,
+				aspeed_mbox_inb(mbox, ASPEED_MBOX_DATA_0 + (i * 4)));
+	}
+	spin_unlock(&mbox->lock);
 #endif
 
 	/* Clear interrupt status */
@@ -249,7 +279,6 @@ static int aspeed_mbox_config_irq(struct aspeed_mbox *mbox,
 {
 	struct device *dev = &pdev->dev;
 	int rc;
-
 	mbox->irq = platform_get_irq(pdev, 0);
 	if (!mbox->irq)
 		return -ENODEV;
@@ -300,6 +329,7 @@ static int aspeed_mbox_probe(struct platform_device *pdev)
 		return -ENODEV;
 	}
 
+	spin_lock_init(&mbox->lock);
 	mutex_init(&mbox->mutex);
 	init_waitqueue_head(&mbox->queue);
 
@@ -313,6 +343,11 @@ static int aspeed_mbox_probe(struct platform_device *pdev)
 		return rc;
 	}
 
+	/* Create FIFO data structure */
+	rc = kfifo_alloc(&mbox->fifo, MBOX_FIFO_SIZE, GFP_KERNEL);
+	if (rc)
+		return rc;
+
 	mbox->miscdev.minor = MISC_DYNAMIC_MINOR;
 	mbox->miscdev.name = DEVICE_NAME;
 	mbox->miscdev.fops = &aspeed_mbox_fops;
@@ -346,6 +381,7 @@ static int aspeed_mbox_remove(struct platform_device *pdev)
 
 	misc_deregister(&mbox->miscdev);
 	clk_disable_unprepare(mbox->clk);
+	kfifo_free(&mbox->fifo);
 
 	return 0;
 }