Extra omap code in linux-omap tree

[linux-2.6-omap-h63xx.git] / drivers / misc / sti / sti-fifo.c

diff --git a/drivers/misc/sti/sti-fifo.c b/drivers/misc/sti/sti-fifo.c
new file mode 100644 (file)
index 0000000..1ea5b18
--- /dev/null
+++ b/drivers/misc/sti/sti-fifo.c
@@ -0,0 +1,117 @@
+/*
+ * STI RX FIFO Support
+ *
+ * Copyright (C) 2005, 2006 Nokia Corporation
+ * Written by:  Paul Mundt <paul.mundt@nokia.com> and
+ *             Roman Tereshonkov <roman.tereshonkov@nokia.com>
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/err.h>
+#include <linux/module.h>
+#include <mach/sti.h>
+
+#define STI_READ_BUFFER_SIZE   1024
+#define sti_buf_pos(pos)       ((sti_crb->bufpos + (pos)) % \
+                                STI_READ_BUFFER_SIZE)
+
+static struct sti_cycle_buffer {
+       int bufpos;
+       int datalen;
+       unsigned char *buf;
+} *sti_crb;
+
+/**
+ * sti_read_packet - STI read packet (read an entire STI packet)
+ * @buf: Buffer to store the packet.
+ * @maxsize: Maximum size requested.
+ *
+ * This reads in a single completed STI packet from the RX FIFOs and
+ * places it in @buf for further processing.
+ *
+ * The return value is < 0 on error, and >= 0 for the number of bytes
+ * actually read. As per the STI specification, we require a 0xC1 to
+ * indicate the end of the packet, and we don't return the packet until
+ * we've read the entire thing in.
+ *
+ * Due to the size of the FIFOs, it's unrealistic to constantly drain
+ * this for 1 or 2 bytes at a time, so we assemble it here and return
+ * the whole thing.
+ */
+int sti_read_packet(unsigned char *buf, int maxsize)
+{
+       unsigned int pos;
+
+       if (unlikely(!buf))
+               return -EINVAL;
+       if (!sti_crb->datalen)
+               return 0;
+
+       pos = sti_buf_pos(sti_crb->datalen - 1);
+       /* End of packet */
+       if (sti_crb->buf[pos] == 0xC1) {
+               int i;
+
+               for (i = 0; i < sti_crb->datalen && i < maxsize; i++) {
+                       pos = sti_buf_pos(i);
+                       buf[i] = sti_crb->buf[pos];
+               }
+
+               sti_crb->bufpos = sti_buf_pos(i);
+               sti_crb->datalen -= i;
+
+               return i;
+       }
+
+       return 0;
+}
+EXPORT_SYMBOL(sti_read_packet);
+
+static void sti_fifo_irq(unsigned long arg)
+{
+       /* If there is data read it */
+       while (!(sti_readl(STI_RX_STATUS) & STI_RXFIFO_EMPTY)) {
+               unsigned int pos = sti_buf_pos(sti_crb->datalen);
+
+               sti_crb->buf[pos] = sti_readl(STI_RX_DR);
+               sti_crb->datalen++;
+       }
+
+       sti_ack_irq(STI_RX_INT);
+}
+
+static int __init sti_fifo_init(void)
+{
+       unsigned int size;
+       int ret;
+
+       size = sizeof(struct sti_cycle_buffer) + STI_READ_BUFFER_SIZE;
+       sti_crb = kmalloc(size, GFP_KERNEL);
+       if (!sti_crb)
+               return -ENOMEM;
+
+       sti_crb->bufpos = sti_crb->datalen = 0;
+       sti_crb->buf = (unsigned char *)(sti_crb + sizeof(*sti_crb));
+
+       ret = sti_request_irq(STI_RX_INT, sti_fifo_irq, 0);
+       if (ret != 0)
+               kfree(sti_crb);
+
+       return ret;
+}
+
+static void __exit sti_fifo_exit(void)
+{
+       sti_free_irq(STI_RX_INT);
+       kfree(sti_crb);
+}
+
+module_init(sti_fifo_init);
+module_exit(sti_fifo_exit);
+
+MODULE_AUTHOR("Paul Mundt, Roman Tereshonkov");
+MODULE_LICENSE("GPL");