[RFC PATCH 8/9] soundwire: intel: remove platform devices and provide new interface

[Pierre-Louis Bossart]

Use sdw_master_device and driver instead of platform devices

To quote GregKH:

"Don't mess with a platform device unless you really have no other
possible choice. And even then, don't do it and try to do something
else. Platform devices are really abused, don't perpetuate it "

In addition, rather than a plain-vanilla init/exit, this patch
provides 3 steps in the initialization (ACPI scan, probe, startup)
which make it easier to verify support and allocate required resources
as early as possible, and conversely help make the startup
lighter-weight with only hardware register setup.

The data structures are also consolidated in a single file and
comments added to help follow what is used for what.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>
---
 drivers/soundwire/intel.c           |  90 +++++----
 drivers/soundwire/intel.h           |  22 +--
 drivers/soundwire/intel_init.c      | 293 +++++++++++++++++++---------
 include/linux/soundwire/sdw_intel.h |  86 +++++++-
 4 files changed, 344 insertions(+), 147 deletions(-)

diff --git a/drivers/soundwire/intel.c b/drivers/soundwire/intel.c
index 8a1f6c627788..267e0fad7494 100644
--- a/drivers/soundwire/intel.c
+++ b/drivers/soundwire/intel.c
@@ -92,8 +92,6 @@
 #define SDW_ALH_STRMZCFG_DMAT		GENMASK(7, 0)
 #define SDW_ALH_STRMZCFG_CHN		GENMASK(19, 16)
 
-#define SDW_INTEL_QUIRK_MASK_BUS_DISABLE	BIT(1)
-
 enum intel_pdi_type {
 	INTEL_PDI_IN = 0,
 	INTEL_PDI_OUT = 1,
@@ -909,24 +907,23 @@ static int intel_init(struct sdw_intel *sdw)
 /*
  * probe and init
  */
-static int intel_probe(struct platform_device *pdev)
+static int intel_master_probe(struct sdw_master_device *md, void *link_ctx)
 {
-	struct sdw_cdns_stream_config config;
 	struct sdw_intel *sdw;
 	int ret;
 
-	sdw = devm_kzalloc(&pdev->dev, sizeof(*sdw), GFP_KERNEL);
+	sdw = devm_kzalloc(&md->dev, sizeof(*sdw), GFP_KERNEL);
 	if (!sdw)
 		return -ENOMEM;
 
-	sdw->instance = pdev->id;
-	sdw->link_res = dev_get_platdata(&pdev->dev);
-	sdw->cdns.dev = &pdev->dev;
+	sdw->instance = md->link_id;
+	sdw->link_res = link_ctx;
+	sdw->cdns.dev = &md->dev;
 	sdw->cdns.registers = sdw->link_res->registers;
-	sdw->cdns.instance = sdw->instance;
+	sdw->cdns.instance = md->link_id;
 	sdw->cdns.msg_count = 0;
-	sdw->cdns.bus.dev = &pdev->dev;
-	sdw->cdns.bus.link_id = pdev->id;
+	sdw->cdns.bus.dev = &md->dev;
+	sdw->cdns.bus.link_id = md->link_id;
 
 	sdw_cdns_probe(&sdw->cdns);
 
@@ -934,16 +931,50 @@ static int intel_probe(struct platform_device *pdev)
 	sdw_intel_ops.read_prop = intel_prop_read;
 	sdw->cdns.bus.ops = &sdw_intel_ops;
 
-	platform_set_drvdata(pdev, sdw);
+	md->pdata = sdw;
+
+	/* set driver data, accessed by snd_soc_dai_set_drvdata() */
+	dev_set_drvdata(&md->dev, &sdw->cdns);
 
 	ret = sdw_add_bus_master(&sdw->cdns.bus);
 	if (ret) {
-		dev_err(&pdev->dev, "sdw_add_bus_master fail: %d\n", ret);
+		dev_err(&md->dev, "sdw_add_bus_master fail: %d\n", ret);
 		return ret;
 	}
 
 	if (sdw->cdns.bus.prop.hw_disabled) {
-		dev_info(&pdev->dev, "SoundWire master %d is disabled, ignoring\n",
+		dev_info(&md->dev, "SoundWire master %d is disabled, ignoring\n",
+			 sdw->cdns.bus.link_id);
+		return 0;
+	}
+
+	/* Acquire IRQ */
+	ret = request_threaded_irq(sdw->link_res->irq,
+				   sdw_cdns_irq, sdw_cdns_thread,
+				   IRQF_SHARED, KBUILD_MODNAME, &sdw->cdns);
+	if (ret < 0) {
+		dev_err(sdw->cdns.dev, "unable to grab IRQ %d, disabling device\n",
+			sdw->link_res->irq);
+		goto err_init;
+	}
+
+	return 0;
+
+err_init:
+	sdw_delete_bus_master(&sdw->cdns.bus);
+	return ret;
+}
+
+static int intel_master_startup(struct sdw_master_device *md)
+{
+	struct sdw_cdns_stream_config config;
+	struct sdw_intel *sdw;
+	int ret;
+
+	sdw = md->pdata;
+
+	if (sdw->cdns.bus.prop.hw_disabled) {
+		dev_info(&md->dev, "SoundWire master %d is disabled, ignoring\n",
 			 sdw->cdns.bus.link_id);
 		return 0;
 	}
@@ -961,16 +992,6 @@ static int intel_probe(struct platform_device *pdev)
 
 	intel_pdi_ch_update(sdw);
 
-	/* Acquire IRQ */
-	ret = request_threaded_irq(sdw->link_res->irq,
-				   sdw_cdns_irq, sdw_cdns_thread,
-				   IRQF_SHARED, KBUILD_MODNAME, &sdw->cdns);
-	if (ret < 0) {
-		dev_err(sdw->cdns.dev, "unable to grab IRQ %d, disabling device\n",
-			sdw->link_res->irq);
-		goto err_init;
-	}
-
 	ret = sdw_cdns_enable_interrupt(&sdw->cdns, true);
 	if (ret < 0) {
 		dev_err(sdw->cdns.dev, "cannot enable interrupts\n");
@@ -997,18 +1018,17 @@ static int intel_probe(struct platform_device *pdev)
 
 err_interrupt:
 	sdw_cdns_enable_interrupt(&sdw->cdns, false);
-err_dai:
-	free_irq(sdw->link_res->irq, sdw);
 err_init:
+	free_irq(sdw->link_res->irq, sdw);
 	sdw_delete_bus_master(&sdw->cdns.bus);
 	return ret;
 }
 
-static int intel_remove(struct platform_device *pdev)
+static int intel_master_remove(struct sdw_master_device *md)
 {
 	struct sdw_intel *sdw;
 
-	sdw = platform_get_drvdata(pdev);
+	sdw = md->pdata;
 
 	if (!sdw->cdns.bus.prop.hw_disabled) {
 		intel_debugfs_exit(sdw);
@@ -1021,16 +1041,12 @@ static int intel_remove(struct platform_device *pdev)
 	return 0;
 }
 
-static struct platform_driver sdw_intel_drv = {
-	.probe = intel_probe,
-	.remove = intel_remove,
-	.driver = {
-		.name = "int-sdw",
-
-	},
+struct sdw_md_driver intel_sdw_driver = {
+	.probe = intel_master_probe,
+	.startup = intel_master_startup,
+	.remove = intel_master_remove,
 };
-
-module_platform_driver(sdw_intel_drv);
+EXPORT_SYMBOL(intel_sdw_driver);
 
 MODULE_LICENSE("Dual BSD/GPL");
 MODULE_ALIAS("platform:int-sdw");
diff --git a/drivers/soundwire/intel.h b/drivers/soundwire/intel.h
index d923b6262330..25cc51e15ef5 100644
--- a/drivers/soundwire/intel.h
+++ b/drivers/soundwire/intel.h
@@ -4,24 +4,8 @@
 #ifndef __SDW_INTEL_LOCAL_H
 #define __SDW_INTEL_LOCAL_H
 
-/**
- * struct sdw_intel_link_res - Soundwire link resources
- * @registers: Link IO registers base
- * @shim: Audio shim pointer
- * @alh: ALH (Audio Link Hub) pointer
- * @irq: Interrupt line
- * @ops: Shim callback ops
- * @arg: Shim callback ops argument
- *
- * This is set as pdata for each link instance.
- */
-struct sdw_intel_link_res {
-	void __iomem *registers;
-	void __iomem *shim;
-	void __iomem *alh;
-	int irq;
-	const struct sdw_intel_ops *ops;
-	void *arg;
-};
+#define SDW_INTEL_QUIRK_MASK_BUS_DISABLE      BIT(1)
+
+extern struct sdw_md_driver intel_sdw_driver;
 
 #endif /* __SDW_INTEL_LOCAL_H */
diff --git a/drivers/soundwire/intel_init.c b/drivers/soundwire/intel_init.c
index d488c44fcbae..47124fc13a4a 100644
--- a/drivers/soundwire/intel_init.c
+++ b/drivers/soundwire/intel_init.c
@@ -11,7 +11,7 @@
 #include <linux/export.h>
 #include <linux/iomap.h>
 #include <linux/module.h>
-#include <linux/platform_device.h>
+#include <linux/soundwire/sdw.h>
 #include <linux/soundwire/sdw_intel.h>
 #include "intel.h"
 
@@ -27,28 +27,45 @@ static int link_mask;
 module_param_named(sdw_link_mask, link_mask, int, 0444);
 MODULE_PARM_DESC(sdw_link_mask, "Intel link mask (one bit per link)");
 
-struct sdw_link_data {
-	struct sdw_intel_link_res res;
-	struct platform_device *pdev;
-};
+static bool is_link_enabled(struct fwnode_handle *fw_node, int i)
+{
+	struct fwnode_handle *link;
+	char name[32];
+	u32 quirk_mask = 0;
 
-struct sdw_intel_ctx {
-	int count;
-	struct sdw_link_data *links;
-};
+	/* Find master handle */
+	snprintf(name, sizeof(name),
+		 "mipi-sdw-link-%d-subproperties", i);
+
+	link = fwnode_get_named_child_node(fw_node, name);
+	if (!link)
+		return false;
 
-static int sdw_intel_cleanup_pdev(struct sdw_intel_ctx *ctx)
+	fwnode_property_read_u32(link,
+				 "intel-quirk-mask",
+				 &quirk_mask);
+
+	if (quirk_mask & SDW_INTEL_QUIRK_MASK_BUS_DISABLE)
+		return false;
+
+	return true;
+}
+
+static int sdw_intel_cleanup(struct sdw_intel_ctx *ctx)
 {
-	struct sdw_link_data *link = ctx->links;
+	struct sdw_intel_link_res *link = ctx->links;
+	struct sdw_master_device *md;
 	int i;
 
 	if (!link)
 		return 0;
 
-	for (i = 0; i < ctx->count; i++) {
-		if (link->pdev)
-			platform_device_unregister(link->pdev);
-		link++;
+	for (i = 0; i < ctx->count; i++, link++) {
+		md = link->md;
+		if (md) {
+			md->driver->remove(md);
+			put_device(&md->dev);
+		}
 	}
 
 	kfree(ctx->links);
@@ -57,115 +74,187 @@ static int sdw_intel_cleanup_pdev(struct sdw_intel_ctx *ctx)
 	return 0;
 }
 
-static struct sdw_intel_ctx
-*sdw_intel_add_controller(struct sdw_intel_res *res)
+static int
+sdw_intel_scan_controller(struct sdw_intel_acpi_info *info)
 {
-	struct platform_device_info pdevinfo;
-	struct platform_device *pdev;
-	struct sdw_link_data *link;
-	struct sdw_intel_ctx *ctx;
 	struct acpi_device *adev;
 	int ret, i;
 	u8 count;
-	u32 caps;
 
-	if (acpi_bus_get_device(res->handle, &adev))
-		return NULL;
+	if (acpi_bus_get_device(info->handle, &adev))
+		return -EINVAL;
 
 	/* Found controller, find links supported */
 	count = 0;
 	ret = fwnode_property_read_u8_array(acpi_fwnode_handle(adev),
 					    "mipi-sdw-master-count", &count, 1);
 
-	/* Don't fail on error, continue and use hw value */
+	/*
+	 * In theory we could check the number of links supported in
+	 * hardware, but in that step we cannot assume SoundWire IP is
+	 * powered.
+	 *
+	 * In addition, if the BIOS doesn't even provide this
+	 * 'master-count' property then all the inits based on link
+	 * masks will fail as well.
+	 *
+	 * We will check the hardware capabilities in the startup() step
+	 */
+
 	if (ret) {
 		dev_err(&adev->dev,
 			"Failed to read mipi-sdw-master-count: %d\n", ret);
-		count = SDW_MAX_LINKS;
+		return -EINVAL;
 	}
 
-	/* Check SNDWLCAP.LCOUNT */
-	caps = ioread32(res->mmio_base + SDW_SHIM_BASE + SDW_SHIM_LCAP);
-	caps &= GENMASK(2, 0);
-
-	/* Check HW supported vs property value and use min of two */
-	count = min_t(u8, caps, count);
-
 	/* Check count is within bounds */
 	if (count > SDW_MAX_LINKS) {
 		dev_err(&adev->dev, "Link count %d exceeds max %d\n",
 			count, SDW_MAX_LINKS);
-		return NULL;
+		return -EINVAL;
 	} else if (!count) {
 		dev_warn(&adev->dev, "No SoundWire links detected\n");
-		return NULL;
+		return -EINVAL;
 	}
+	dev_dbg(&adev->dev, "Detected %d SDW Link devices\n", count);
 
+	info->count = count;
+
+	for (i = 0; i < count; i++) {
+		if (link_mask && !(link_mask & BIT(i))) {
+			dev_dbg(&adev->dev,
+				"Link %d masked, will not be enabled\n", i);
+			continue;
+		}
+
+		if (!is_link_enabled(acpi_fwnode_handle(adev), i))
+			continue;
+
+		info->link_mask |= BIT(i);
+	}
+
+	return 0;
+}
+
+static struct sdw_intel_ctx
+*sdw_intel_probe_controller(struct sdw_intel_res *res)
+{
+	struct sdw_intel_link_res *link;
+	struct sdw_intel_ctx *ctx;
+	struct acpi_device *adev;
+	struct sdw_master_device *md;
+	u32 link_mask;
+	int count;
+	int i;
+
+	if (acpi_bus_get_device(res->handle, &adev))
+		return NULL;
+
+	if (!res || !res->count)
+		return NULL;
+
+	count = res->count;
 	dev_dbg(&adev->dev, "Creating %d SDW Link devices\n", count);
 
 	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
 	if (!ctx)
 		return NULL;
 
-	ctx->count = count;
-	ctx->links = kcalloc(ctx->count, sizeof(*ctx->links), GFP_KERNEL);
+	ctx->links = kcalloc(count, sizeof(*ctx->links), GFP_KERNEL);
 	if (!ctx->links)
 		goto link_err;
 
+	ctx->count = count;
+	ctx->mmio_base = res->mmio_base;
+	ctx->link_mask = res->link_mask;
+	ctx->handle = res->handle;
+
 	link = ctx->links;
+	link_mask = ctx->link_mask;
 
 	/* Create SDW Master devices */
-	for (i = 0; i < count; i++) {
-		if (link_mask && !(link_mask & BIT(i))) {
-			dev_dbg(&adev->dev,
-				"Link %d masked, will not be enabled\n", i);
-			link++;
+	for (i = 0; i < count; i++, link++) {
+		if (link_mask && !(link_mask & BIT(i)))
 			continue;
-		}
 
-		link->res.irq = res->irq;
-		link->res.registers = res->mmio_base + SDW_LINK_BASE
-					+ (SDW_LINK_SIZE * i);
-		link->res.shim = res->mmio_base + SDW_SHIM_BASE;
-		link->res.alh = res->mmio_base + SDW_ALH_BASE;
-
-		link->res.ops = res->ops;
-		link->res.arg = res->arg;
-
-		memset(&pdevinfo, 0, sizeof(pdevinfo));
-
-		pdevinfo.parent = res->parent;
-		pdevinfo.name = "int-sdw";
-		pdevinfo.id = i;
-		pdevinfo.fwnode = acpi_fwnode_handle(adev);
-		pdevinfo.data = &link->res;
-		pdevinfo.size_data = sizeof(link->res);
-
-		pdev = platform_device_register_full(&pdevinfo);
-		if (IS_ERR(pdev)) {
-			dev_err(&adev->dev,
-				"platform device creation failed: %ld\n",
-				PTR_ERR(pdev));
-			goto pdev_err;
-		}
+		md = sdw_md_add(&intel_sdw_driver,
+				&adev->dev,
+				acpi_fwnode_handle(adev),
+				i);
 
-		link->pdev = pdev;
-		link++;
+		if (IS_ERR(md)) {
+			dev_err(&adev->dev, "Could not create link %d\n", i);
+			goto err;
+		}
+		link->md = md;
+		link->mmio_base = res->mmio_base;
+		link->registers = res->mmio_base + SDW_LINK_BASE
+			+ (SDW_LINK_SIZE * i);
+		link->shim = res->mmio_base + SDW_SHIM_BASE;
+		link->alh = res->mmio_base + SDW_ALH_BASE;
+		link->irq = res->irq;
+		link->ops = res->ops;
+		link->arg = res->arg;
+
+		/* let the SoundWire master driver to its probe */
+		md->driver->probe(md, link);
 	}
 
 	return ctx;
 
-pdev_err:
-	sdw_intel_cleanup_pdev(ctx);
+err:
+	sdw_intel_cleanup(ctx);
 link_err:
 	kfree(ctx);
 	return NULL;
 }
 
+static int
+sdw_intel_startup_controller(struct sdw_intel_ctx *ctx)
+{
+	struct acpi_device *adev;
+	struct sdw_intel_link_res *link;
+	struct sdw_master_device *md;
+	u32 caps;
+	int i;
+
+	if (acpi_bus_get_device(ctx->handle, &adev))
+		return -EINVAL;
+
+	/* Check SNDWLCAP.LCOUNT */
+	caps = ioread32(ctx->mmio_base + SDW_SHIM_BASE + SDW_SHIM_LCAP);
+	caps &= GENMASK(2, 0);
+
+	/* Check HW supported vs property value */
+	if (caps < ctx->count) {
+		dev_err(&adev->dev,
+			"BIOS master count is larger than hardware capabilities\n");
+		return -EINVAL;
+	}
+
+	if (!ctx->links)
+		return -EINVAL;
+
+	link = ctx->links;
+	link_mask = ctx->link_mask;
+
+	/* Create SDW Master devices */
+	for (i = 0; i < ctx->count; i++, link++) {
+		if (link_mask && !(link_mask & BIT(i)))
+			continue;
+
+		md = link->md;
+
+		md->driver->startup(md);
+	}
+
+	return 0;
+}
+
 static acpi_status sdw_intel_acpi_cb(acpi_handle handle, u32 level,
 				     void *cdata, void **return_value)
 {
-	struct sdw_intel_res *res = cdata;
+	struct sdw_intel_acpi_info *info = cdata;
 	struct acpi_device *adev;
 	acpi_status status;
 	u64 adr;
@@ -179,7 +268,7 @@ static acpi_status sdw_intel_acpi_cb(acpi_handle handle, u32 level,
 		return AE_NOT_FOUND;
 	}
 
-	res->handle = handle;
+	info->handle = handle;
 
 	/*
 	 * On some Intel platforms, multiple children of the HDAS
@@ -196,40 +285,68 @@ static acpi_status sdw_intel_acpi_cb(acpi_handle handle, u32 level,
 }
 
 /**
- * sdw_intel_init() - SoundWire Intel init routine
+ * sdw_intel_acpi_scan() - SoundWire Intel init routine
  * @parent_handle: ACPI parent handle
- * @res: resource data
+ * @info: description of what firmware/DSDT tables expose
  *
- * This scans the namespace and creates SoundWire link controller devices
- * based on the info queried.
+ * This scans the namespace and queries firmware to figure out which
+ * links to enable. A follow-up use of sdw_intel_probe() and
+ * sdw_intel_startup() is required for creation of devices and bus
+ * startup
  */
-void *sdw_intel_init(acpi_handle *parent_handle, struct sdw_intel_res *res)
+int sdw_intel_acpi_scan(acpi_handle *parent_handle,
+			struct sdw_intel_acpi_info *info)
 {
 	acpi_status status;
 
 	status = acpi_walk_namespace(ACPI_TYPE_DEVICE,
 				     parent_handle, 1,
 				     sdw_intel_acpi_cb,
-				     NULL, res, NULL);
+				     NULL, info, NULL);
 	if (ACPI_FAILURE(status))
-		return NULL;
+		return -ENODEV;
 
-	return sdw_intel_add_controller(res);
+	return sdw_intel_scan_controller(info);
 }
-EXPORT_SYMBOL(sdw_intel_init);
+EXPORT_SYMBOL(sdw_intel_acpi_scan);
 
+/**
+ * sdw_intel_probe() - SoundWire Intel probe routine
+ * @parent_handle: ACPI parent handle
+ * @res: resource data
+ *
+ * This creates SoundWire Master and Slave devices below the controller.
+ * All the information necessary is stored in the context, and the res
+ * argument pointer can be freed after this step.
+ */
+struct sdw_intel_ctx
+*sdw_intel_probe(struct sdw_intel_res *res)
+{
+	return sdw_intel_probe_controller(res);
+}
+EXPORT_SYMBOL(sdw_intel_probe);
+
+/**
+ * sdw_intel_startup() - SoundWire Intel startup
+ * @ctx: SoundWire context allocated in the probe
+ *
+ */
+int sdw_intel_startup(struct sdw_intel_ctx *ctx)
+{
+	return sdw_intel_startup_controller(ctx);
+}
+EXPORT_SYMBOL(sdw_intel_startup);
 /**
  * sdw_intel_exit() - SoundWire Intel exit
- * @arg: callback context
+ * @ctx: SoundWire context allocated in the probe
  *
  * Delete the controller instances created and cleanup
  */
-void sdw_intel_exit(void *arg)
+void sdw_intel_exit(struct sdw_intel_ctx *ctx)
 {
-	struct sdw_intel_ctx *ctx = arg;
-
-	sdw_intel_cleanup_pdev(ctx);
+	sdw_intel_cleanup(ctx);
 	kfree(ctx);
+	ctx = NULL;
 }
 EXPORT_SYMBOL(sdw_intel_exit);
 
diff --git a/include/linux/soundwire/sdw_intel.h b/include/linux/soundwire/sdw_intel.h
index c9427cb6020b..0ce3e4023074 100644
--- a/include/linux/soundwire/sdw_intel.h
+++ b/include/linux/soundwire/sdw_intel.h
@@ -16,24 +16,104 @@ struct sdw_intel_ops {
 };
 
 /**
- * struct sdw_intel_res - Soundwire Intel resource structure
+ * struct sdw_intel_acpi_info - Soundwire Intel information found in ACPI tables
+ * @handle: ACPI controller handle
+ * @count: link count found with "sdw-master-count" property
+ * @link_mask: bit-wise mask listing links enabled by BIOS menu
+ *
+ * this structure could be expanded to e.g. provide all the _ADR
+ * information in case the link_mask is not sufficient to identify
+ * platform capabilities.
+ */
+struct sdw_intel_acpi_info {
+	acpi_handle handle;
+	int count;
+	u32 link_mask;
+};
+
+/**
+ * struct sdw_intel_res - Soundwire Intel global resource structure,
+ * typically populated by the DSP driver
+ *
+ * @count: link count (may be filtered by DSP driver)
  * @mmio_base: mmio base of SoundWire registers
  * @irq: interrupt number
  * @handle: ACPI parent handle
  * @parent: parent device
  * @ops: callback ops
  * @arg: callback arg
+ * @link_mask: bit-wise mask listing links selected by the DSP driver
  */
 struct sdw_intel_res {
+	int count;
 	void __iomem *mmio_base;
 	int irq;
 	acpi_handle handle;
 	struct device *parent;
 	const struct sdw_intel_ops *ops;
 	void *arg;
+	u32 link_mask;
 };
 
-void *sdw_intel_init(acpi_handle *parent_handle, struct sdw_intel_res *res);
-void sdw_intel_exit(void *arg);
+/**
+ * struct sdw_intel_link_res - Soundwire Intel link resource structure,
+ * typically populated by the controller driver.
+ * @md: Master device
+ * @mmio_base: mmio base of SoundWire registers
+ * @registers: Link IO registers base
+ * @shim: Audio shim pointer
+ * @alh: ALH (Audio Link Hub) pointer
+ * @irq: Interrupt line
+ * @ops: Shim callback ops
+ * @arg: Shim callback ops argument
+ */
+struct sdw_intel_link_res {
+	struct sdw_master_device *md;
+	void __iomem *mmio_base; /* not strictly needed, useful for debug */
+	void __iomem *registers;
+	void __iomem *shim;
+	void __iomem *alh;
+	int irq;
+	const struct sdw_intel_ops *ops;
+	void *arg;
+};
+
+/**
+ * struct sdw_intel_ctx - context allocated by the controller
+ * driver probe
+ * @count: link count
+ * @mmio_base: mmio base of SoundWire registers, only used to check
+ * hardware capabilities after all power dependencies are settled.
+ * @arg: Shim callback ops argument
+ */
+struct sdw_intel_ctx {
+	int count;
+	void __iomem *mmio_base;
+	u32 link_mask;
+	acpi_handle handle;
+	struct sdw_intel_link_res *links;
+};
+
+/*
+ * On Intel platforms, the SoundWire IP has dependencies on power
+ * rails shared with the DSP, and the initialization steps are split
+ * in three. First an ACPI scan to check what the firmware describes
+ * in DSDT tables, then an allocation step (with no hardware
+ * configuration but with all the relevant devices created) and last
+ * the actual hardware configuration. The final stage is a global
+ * interrupt enable which is controlled by the DSP driver. Splitting
+ * these phases helps simplify the boot flow and make early decisions
+ * on e.g. which machine driver to select (I2S mode, HDaudio or
+ * SoundWire).
+ */
+int sdw_intel_acpi_scan(acpi_handle *parent_handle,
+			struct sdw_intel_acpi_info *info);
+
+struct sdw_intel_ctx *
+sdw_intel_probe(struct sdw_intel_res *res);
+
+int sdw_intel_startup(struct sdw_intel_ctx *ctx);
+
+void sdw_intel_exit(struct sdw_intel_ctx *ctx);
 
 #endif
-- 
2.20.1