1 files changed, 223 insertions, 0 deletions

diff --git a/sound/firewire/fcp.c b/sound/firewire/fcp.c
new file mode 100644
index 000000000000..c20bd9c8f5ab
--- /dev/null
+++ b/sound/firewire/fcp.c
@@ -0,0 +1,223 @@
+/*
+ * Function Control Protocol (IEC 61883-1) helper functions
+ *
+ * Copyright (c) Clemens Ladisch <clemens@ladisch.de>
+ * Licensed under the terms of the GNU General Public License, version 2.
+ */
+
+#include <linux/device.h>
+#include <linux/firewire.h>
+#include <linux/firewire-constants.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/spinlock.h>
+#include <linux/wait.h>
+#include "fcp.h"
+#include "lib.h"
+
+#define CTS_AVC 0x00
+
+#define ERROR_RETRIES   3
+#define ERROR_DELAY_MS  5
+#define FCP_TIMEOUT_MS  125
+
+static DEFINE_SPINLOCK(transactions_lock);
+static LIST_HEAD(transactions);
+
+enum fcp_state {
+        STATE_PENDING,
+        STATE_BUS_RESET,
+        STATE_COMPLETE,
+};
+
+struct fcp_transaction {
+        struct list_head list;
+        struct fw_unit *unit;
+        void *response_buffer;
+        unsigned int response_size;
+        unsigned int response_match_bytes;
+        enum fcp_state state;
+        wait_queue_head_t wait;
+};
+
+/**
+ * fcp_avc_transaction - send an AV/C command and wait for its response
+ * @unit: a unit on the target device
+ * @command: a buffer containing the command frame; must be DMA-able
+ * @command_size: the size of @command
+ * @response: a buffer for the response frame
+ * @response_size: the maximum size of @response
+ * @response_match_bytes: a bitmap specifying the bytes used to detect the
+ *                        correct response frame
+ *
+ * This function sends a FCP command frame to the target and waits for the
+ * corresponding response frame to be returned.
+ *
+ * Because it is possible for multiple FCP transactions to be active at the
+ * same time, the correct response frame is detected by the value of certain
+ * bytes.  These bytes must be set in @response before calling this function,
+ * and the corresponding bits must be set in @response_match_bytes.
+ *
+ * @command and @response can point to the same buffer.
+ *
+ * Asynchronous operation (INTERIM, NOTIFY) is not supported at the moment.
+ *
+ * Returns the actual size of the response frame, or a negative error code.
+ */
+int fcp_avc_transaction(struct fw_unit *unit,
+                        const void *command, unsigned int command_size,
+                        void *response, unsigned int response_size,
+                        unsigned int response_match_bytes)
+{
+        struct fcp_transaction t;
+        int tcode, ret, tries = 0;
+
+        t.unit = unit;
+        t.response_buffer = response;
+        t.response_size = response_size;
+        t.response_match_bytes = response_match_bytes;
+        t.state = STATE_PENDING;
+        init_waitqueue_head(&t.wait);
+
+        spin_lock_irq(&transactions_lock);
+        list_add_tail(&t.list, &transactions);
+        spin_unlock_irq(&transactions_lock);
+
+        for (;;) {
+                tcode = command_size == 4 ? TCODE_WRITE_QUADLET_REQUEST
+                                          : TCODE_WRITE_BLOCK_REQUEST;
+                ret = snd_fw_transaction(t.unit, tcode,
+                                         CSR_REGISTER_BASE + CSR_FCP_COMMAND,
+                                         (void *)command, command_size);
+                if (ret < 0)
+                        break;
+
+                wait_event_timeout(t.wait, t.state != STATE_PENDING,
+                                   msecs_to_jiffies(FCP_TIMEOUT_MS));
+
+                if (t.state == STATE_COMPLETE) {
+                        ret = t.response_size;
+                        break;
+                } else if (t.state == STATE_BUS_RESET) {
+                        msleep(ERROR_DELAY_MS);
+                } else if (++tries >= ERROR_RETRIES) {
+                        dev_err(&t.unit->device, "FCP command timed out\n");
+                        ret = -EIO;
+                        break;
+                }
+        }
+
+        spin_lock_irq(&transactions_lock);
+        list_del(&t.list);
+        spin_unlock_irq(&transactions_lock);
+
+        return ret;
+}
+EXPORT_SYMBOL(fcp_avc_transaction);
+
+/**
+ * fcp_bus_reset - inform the target handler about a bus reset
+ * @unit: the unit that might be used by fcp_avc_transaction()
+ *
+ * This function must be called from the driver's .update handler to inform
+ * the FCP transaction handler that a bus reset has happened.  Any pending FCP
+ * transactions are retried.
+ */
+void fcp_bus_reset(struct fw_unit *unit)
+{
+        struct fcp_transaction *t;
+
+        spin_lock_irq(&transactions_lock);
+        list_for_each_entry(t, &transactions, list) {
+                if (t->unit == unit &&
+                    t->state == STATE_PENDING) {
+                        t->state = STATE_BUS_RESET;
+                        wake_up(&t->wait);
+                }
+        }
+        spin_unlock_irq(&transactions_lock);
+}
+EXPORT_SYMBOL(fcp_bus_reset);
+
+/* checks whether the response matches the masked bytes in response_buffer */
+static bool is_matching_response(struct fcp_transaction *transaction,
+                                 const void *response, size_t length)
+{
+        const u8 *p1, *p2;
+        unsigned int mask, i;
+
+        p1 = response;
+        p2 = transaction->response_buffer;
+        mask = transaction->response_match_bytes;
+
+        for (i = 0; ; ++i) {
+                if ((mask & 1) && p1[i] != p2[i])
+                        return false;
+                mask >>= 1;
+                if (!mask)
+                        return true;
+                if (--length == 0)
+                        return false;
+        }
+}
+
+static void fcp_response(struct fw_card *card, struct fw_request *request,
+                         int tcode, int destination, int source,
+                         int generation, unsigned long long offset,
+                         void *data, size_t length, void *callback_data)
+{
+        struct fcp_transaction *t;
+        unsigned long flags;
+
+        if (length < 1 || (*(const u8 *)data & 0xf0) != CTS_AVC)
+                return;
+
+        spin_lock_irqsave(&transactions_lock, flags);
+        list_for_each_entry(t, &transactions, list) {
+                struct fw_device *device = fw_parent_device(t->unit);
+                if (device->card != card ||
+                    device->generation != generation)
+                        continue;
+                smp_rmb(); /* node_id vs. generation */
+                if (device->node_id != source)
+                        continue;
+
+                if (t->state == STATE_PENDING &&
+                    is_matching_response(t, data, length)) {
+                        t->state = STATE_COMPLETE;
+                        t->response_size = min((unsigned int)length,
+                                               t->response_size);
+                        memcpy(t->response_buffer, data, t->response_size);
+                        wake_up(&t->wait);
+                }
+        }
+        spin_unlock_irqrestore(&transactions_lock, flags);
+}
+
+static struct fw_address_handler response_register_handler = {
+        .length = 0x200,
+        .address_callback = fcp_response,
+};
+
+static int __init fcp_module_init(void)
+{
+        static const struct fw_address_region response_register_region = {
+                .start = CSR_REGISTER_BASE + CSR_FCP_RESPONSE,
+                .end = CSR_REGISTER_BASE + CSR_FCP_END,
+        };
+
+        fw_core_add_address_handler(&response_register_handler,
+                                    &response_register_region);
+
+        return 0;
+}
+
+static void __exit fcp_module_exit(void)
+{
+        WARN_ON(!list_empty(&transactions));
+        fw_core_remove_address_handler(&response_register_handler);
+}
+
+module_init(fcp_module_init);
+module_exit(fcp_module_exit);