ASoC: SDCA: Add completion for FDL start and stop

Add some completions and a helper function to allow other parts of the
system to wait for FDL to complete. The sdca_fdl_sync() function will
wait until it completes a full time out without a new FDL request
happening, this ensures that even parts requiring multiple rounds of FDL
should be fully downloaded before the driver boot continues.

Reviewed-by: Bard Liao <[e-mail]>
Signed-off-by: Charles Keepax <[e-mail]>
Reviewed-by: Pierre-Louis Bossart <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

include/sound/sdca_fdl.h

···
 #ifndef __SDCA_FDL_H__
 #define __SDCA_FDL_H__
 
+#include <linux/completion.h>
+
 struct device;
 struct regmap;
 struct sdca_fdl_set;
 struct sdca_function_data;
 struct sdca_interrupt;
+struct sdca_interrupt_info;
 
 /**
  * struct fdl_state - FDL state structure to keep data between interrupts
+ * @begin: Completion indicating the start of an FDL download cycle.
+ * @done: Completion indicating the end of an FDL download cycle.
  * @set: Pointer to the FDL set currently being downloaded.
  * @file_index: Index of the current file being processed.
  */
 struct fdl_state {
+	struct completion begin;
+	struct completion done;
+
 	struct sdca_fdl_set *set;
 	int file_index;
 };
···
 
 int sdca_fdl_alloc_state(struct sdca_interrupt *interrupt);
 int sdca_fdl_process(struct sdca_interrupt *interrupt);
+int sdca_fdl_sync(struct device *dev, struct sdca_function_data *function,
+		  struct sdca_interrupt_info *info);
 
 int sdca_reset_function(struct device *dev, struct sdca_function_data *function,
 			struct regmap *regmap);

sound/soc/sdca/sdca_fdl.c

···
 #include <linux/firmware.h>
 #include <linux/module.h>
 #include <linux/pci.h>
+#include <linux/pm_runtime.h>
 #include <linux/regmap.h>
 #include <linux/sprintf.h>
 #include <linux/soundwire/sdw.h>
···
 	return 0;
 }
 EXPORT_SYMBOL_NS(sdca_reset_function, "SND_SOC_SDCA");
+
+/**
+ * sdca_fdl_sync - wait for a function to finish FDL
+ * @dev: Device pointer for error messages.
+ * @function: Pointer to the SDCA Function.
+ * @info: Pointer to the SDCA interrupt info for this device.
+ *
+ * Return: Zero on success or a negative error code.
+ */
+int sdca_fdl_sync(struct device *dev, struct sdca_function_data *function,
+		  struct sdca_interrupt_info *info)
+{
+	static const int fdl_retries = 6;
+	unsigned long begin_timeout = msecs_to_jiffies(100);
+	unsigned long done_timeout = msecs_to_jiffies(4000);
+	int nfdl;
+	int i, j;
+
+	for (i = 0; i < fdl_retries; i++) {
+		nfdl = 0;
+
+		for (j = 0; j < SDCA_MAX_INTERRUPTS; j++) {
+			struct sdca_interrupt *interrupt = &info->irqs[j];
+			struct fdl_state *fdl_state;
+			unsigned long time;
+
+			if (interrupt->function != function ||
+			    !interrupt->entity || !interrupt->control ||
+			    interrupt->entity->type != SDCA_ENTITY_TYPE_XU ||
+			    interrupt->control->sel != SDCA_CTL_XU_FDL_CURRENTOWNER)
+				continue;
+
+			fdl_state = interrupt->priv;
+			nfdl++;
+
+			/*
+			 * Looking for timeout without any new FDL requests
+			 * to imply the device has completed initial
+			 * firmware setup. Alas the specification doesn't
+			 * have any mechanism to detect this.
+			 */
+			time = wait_for_completion_timeout(&fdl_state->begin,
+							   begin_timeout);
+			if (!time) {
+				dev_dbg(dev, "no new FDL starts\n");
+				nfdl--;
+				continue;
+			}
+
+			time = wait_for_completion_timeout(&fdl_state->done,
+							   done_timeout);
+			if (!time) {
+				dev_err(dev, "timed out waiting for FDL to complete\n");
+				return -ETIMEDOUT;
+			}
+		}
+
+		if (!nfdl)
+			return 0;
+	}
+
+	dev_err(dev, "too many FDL requests\n");
+	return -ETIMEDOUT;
+}
+EXPORT_SYMBOL_NS_GPL(sdca_fdl_sync, "SND_SOC_SDCA");
 
 static char *fdl_get_sku_filename(struct device *dev,
 				  struct sdca_fdl_file *fdl_file)
···
 
 	fdl_state->set = NULL;
 
+	pm_runtime_put(interrupt->dev);
+	complete(&fdl_state->done);
+
 	dev_dbg(interrupt->dev, "completed FDL process\n");
 }
 
···
 	switch (status) {
 	case SDCA_CTL_XU_FDLD_NEEDS_SET:
 		dev_dbg(interrupt->dev, "starting FDL process...\n");
+
+		pm_runtime_get(interrupt->dev);
+		complete(&fdl_state->begin);
 
 		fdl_state->file_index = 0;
 		fdl_state->set = fdl_get_set(interrupt);
···
 	fdl_state = devm_kzalloc(dev, sizeof(struct fdl_state), GFP_KERNEL);
 	if (!fdl_state)
 		return -ENOMEM;
+
+	init_completion(&fdl_state->begin);
+	init_completion(&fdl_state->done);
 
 	interrupt->priv = fdl_state;