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);