Re: [PATCH v4] soundwire: intel: move to auxiliary bus

On 5/11/21 12:21 AM, Bard Liao wrote:

From: Pierre-Louis Bossart pierre-louis.bossart@linux.intel.com

Now that the auxiliary_bus exists, there's no reason to use platform devices as children of a PCI device any longer.

This patch refactors the code by extending a basic auxiliary device with Intel link-specific structures that need to be passed between controller and link levels. This refactoring is much cleaner with no need for cross-pointers between device and link structures.

Note that the auxiliary bus API has separate init and add steps, which requires more attention in the error unwinding paths. The main loop needs to deal with kfree() and auxiliary_device_uninit() for the current iteration before jumping to the common label which releases everything allocated in prior iterations.

Signed-off-by: Pierre-Louis Bossart pierre-louis.bossart@linux.intel.com Reviewed-by: Guennadi Liakhovetski guennadi.liakhovetski@linux.intel.com Reviewed-by: Ranjani Sridharan ranjani.sridharan@linux.intel.com Signed-off-by: Bard Liao yung-chuan.liao@linux.intel.com

---

v2:

• add link_dev_register for all kzalloc, device_init, and device_add.

v3:

• Modify the function description of sdw_intel_probe() which was missing in previous version.

v4:

• Move intel_link_dev_unregister(ldev) before pm_runtime_put_noidle( ldev->link_res.dev) to fix use-after-free reported by KASAN.

Two years ago, GregKH stated in https://lore.kernel.org/lkml/20190509181812.GA10776@kroah.com/

"So soundwire is creating platform devices? Ick, no! Don't do that"

Fast forward two years, this patch provides a solution to remove the use of the platform devices with the auxiliary bus. This move does not add any new functionality, it's just a replacement of one type of device by another.

The reviews have been rather limited since the first version shared on March 22.

a) I updated the code to follow the model of the Mellanox driver in

https://elixir.bootlin.com/linux/latest/source/include/linux/mlx5/driver.h#L...

I hope this addresses GregKH's feedback on the need for a 'register' function to combined the two init and add steps. I didn't see a path to add a generic register function in the auxiliary bus code since between init and add there is a need to setup domain-specific structures. Other contributors to the auxiliary bus (CC:ed) also didn't have a burning desire to add this capability.

b) Vinod commented:

"What I would like to see the end result is that sdw driver for Intel controller here is a simple auxdev device and no additional custom setup layer required... which implies that this handling should be moved into auxdev or Intel code setting up auxdev..."

I was unable to figure out what this comment hinted at: the auxbus is already handled in the intel_init.c and intel.c files and the auxbus is used to model a set of links/managers below the PCI device, not the controller itself. There is also no such thing as a simple auxdev device used in the kernel today, the base layer is meant to be extended with domain-specific structures. There is really no point in creating a simple auxbus device without extensions.

My reply from March 24 which included technical details on how the auxiliary bus is designed was not followed by any replies/comments from Vinod, so I don't know if there is agreement or still a disconnect.

I understand everyone is busy, but I could use more feedback on this patch. Vinod and Greg can you please chime in on this v4?

Thank you.

---

drivers/soundwire/Kconfig | 1 + drivers/soundwire/intel.c | 56 ++++--- drivers/soundwire/intel.h | 14 +- drivers/soundwire/intel_init.c | 232 +++++++++++++++++++--------- include/linux/soundwire/sdw_intel.h | 6 +- 5 files changed, 202 insertions(+), 107 deletions(-)

diff --git a/drivers/soundwire/Kconfig b/drivers/soundwire/Kconfig index 016e74230bb7..2b7795233282 100644 --- a/drivers/soundwire/Kconfig +++ b/drivers/soundwire/Kconfig @@ -25,6 +25,7 @@ config SOUNDWIRE_INTEL tristate "Intel SoundWire Master driver" select SOUNDWIRE_CADENCE select SOUNDWIRE_GENERIC_ALLOCATION

• select AUXILIARY_BUS depends on ACPI && SND_SOC help SoundWire Intel Master driver.

diff --git a/drivers/soundwire/intel.c b/drivers/soundwire/intel.c index fd95f94630b1..c11e3d8cd308 100644 --- a/drivers/soundwire/intel.c +++ b/drivers/soundwire/intel.c @@ -11,7 +11,7 @@ #include <linux/module.h> #include <linux/interrupt.h> #include <linux/io.h> -#include <linux/platform_device.h> +#include <linux/auxiliary_bus.h> #include <sound/pcm_params.h> #include <linux/pm_runtime.h> #include <sound/soc.h> @@ -1327,11 +1327,14 @@ static int intel_init(struct sdw_intel *sdw) }

/*

• • probe and init

• • probe and init (aux_dev_id argument is required by function prototype but not used)
  */

-static int intel_master_probe(struct platform_device *pdev) +static int intel_link_probe(struct auxiliary_device *auxdev,

• 	    const struct auxiliary_device_id *aux_dev_id)
  

• {

• struct device *dev = &pdev->dev;

• struct device *dev = &auxdev->dev;
• struct sdw_intel_link_dev *ldev = auxiliary_dev_to_sdw_intel_link_dev(auxdev); struct sdw_intel *sdw; struct sdw_cdns *cdns; struct sdw_bus *bus;

@@ -1344,14 +1347,14 @@ static int intel_master_probe(struct platform_device *pdev) cdns = &sdw->cdns; bus = &cdns->bus;

• sdw->instance = pdev->id;
• sdw->link_res = dev_get_platdata(dev);

• sdw->instance = auxdev->id;
• sdw->link_res = &ldev->link_res; cdns->dev = dev; cdns->registers = sdw->link_res->registers; cdns->instance = sdw->instance; cdns->msg_count = 0;

• bus->link_id = pdev->id;

• bus->link_id = auxdev->id;

  sdw_cdns_probe(cdns);

@@ -1384,10 +1387,10 @@ static int intel_master_probe(struct platform_device *pdev) return 0; }

-int intel_master_startup(struct platform_device *pdev) +int intel_link_startup(struct auxiliary_device *auxdev) { struct sdw_cdns_stream_config config;

• struct device *dev = &pdev->dev;

• struct device *dev = &auxdev->dev; struct sdw_cdns *cdns = dev_get_drvdata(dev); struct sdw_intel *sdw = cdns_to_intel(cdns); struct sdw_bus *bus = &cdns->bus;

@@ -1524,9 +1527,9 @@ int intel_master_startup(struct platform_device *pdev) return ret; }

-static int intel_master_remove(struct platform_device *pdev) +static void intel_link_remove(struct auxiliary_device *auxdev) {

• struct device *dev = &pdev->dev;

• struct device *dev = &auxdev->dev; struct sdw_cdns *cdns = dev_get_drvdata(dev); struct sdw_intel *sdw = cdns_to_intel(cdns); struct sdw_bus *bus = &cdns->bus;

@@ -1542,19 +1545,17 @@ static int intel_master_remove(struct platform_device *pdev) snd_soc_unregister_component(dev); } sdw_bus_master_delete(bus);

• return 0; }

-int intel_master_process_wakeen_event(struct platform_device *pdev) +int intel_link_process_wakeen_event(struct auxiliary_device *auxdev) {

• struct device *dev = &pdev->dev;

• struct device *dev = &auxdev->dev; struct sdw_intel *sdw; struct sdw_bus *bus; void __iomem *shim; u16 wake_sts;

• sdw = platform_get_drvdata(pdev);

• sdw = dev_get_drvdata(dev); bus = &sdw->cdns.bus;

  if (bus->prop.hw_disabled) {

@@ -1976,17 +1977,22 @@ static const struct dev_pm_ops intel_pm = { SET_RUNTIME_PM_OPS(intel_suspend_runtime, intel_resume_runtime, NULL) };

-static struct platform_driver sdw_intel_drv = {

• .probe = intel_master_probe,
• .remove = intel_master_remove,

+static const struct auxiliary_device_id intel_link_id_table[] = {

• { .name = "soundwire_intel.link" },
• {},

+}; +MODULE_DEVICE_TABLE(auxiliary, intel_link_id_table);

+static struct auxiliary_driver sdw_intel_drv = {

• .probe = intel_link_probe,
• .remove = intel_link_remove, .driver = {

• .name = "intel-sdw",
  

• /* auxiliary_driver_register() sets .name to be the modname */
  

  .pm = &intel_pm,

• }

• },
• .id_table = intel_link_id_table };

-module_platform_driver(sdw_intel_drv); +module_auxiliary_driver(sdw_intel_drv);

MODULE_LICENSE("Dual BSD/GPL"); -MODULE_ALIAS("platform:intel-sdw"); -MODULE_DESCRIPTION("Intel Soundwire Master Driver"); +MODULE_DESCRIPTION("Intel Soundwire Link Driver"); diff --git a/drivers/soundwire/intel.h b/drivers/soundwire/intel.h index 06bac8ba14e9..0b47b148da3f 100644 --- a/drivers/soundwire/intel.h +++ b/drivers/soundwire/intel.h @@ -7,7 +7,6 @@ /**

• struct sdw_intel_link_res - Soundwire Intel link resource structure,
• typically populated by the controller driver.

• • @pdev: platform_device
  • @mmio_base: mmio base of SoundWire registers
  • @registers: Link IO registers base
  • @shim: Audio shim pointer

@@ -23,7 +22,6 @@

• @list: used to walk-through all masters exposed by the same controller

*/ struct sdw_intel_link_res {

• struct platform_device *pdev; void __iomem *mmio_base; /* not strictly needed, useful for debug */ void __iomem *registers; void __iomem *shim;

@@ -48,7 +46,15 @@ struct sdw_intel { #endif };

-int intel_master_startup(struct platform_device *pdev); -int intel_master_process_wakeen_event(struct platform_device *pdev); +int intel_link_startup(struct auxiliary_device *auxdev); +int intel_link_process_wakeen_event(struct auxiliary_device *auxdev);

+struct sdw_intel_link_dev {

• struct auxiliary_device auxdev;
• struct sdw_intel_link_res link_res;

+};

+#define auxiliary_dev_to_sdw_intel_link_dev(auxiliary_dev) \

• container_of(auxiliary_dev, struct sdw_intel_link_dev, auxdev)

  #endif /* __SDW_INTEL_LOCAL_H */

diff --git a/drivers/soundwire/intel_init.c b/drivers/soundwire/intel_init.c index 30ce95ec2d70..9e283bef53d2 100644 --- a/drivers/soundwire/intel_init.c +++ b/drivers/soundwire/intel_init.c @@ -12,7 +12,7 @@ #include <linux/interrupt.h> #include <linux/io.h> #include <linux/module.h> -#include <linux/platform_device.h> +#include <linux/auxiliary_bus.h> #include <linux/pm_runtime.h> #include <linux/soundwire/sdw_intel.h> #include "cadence_master.h" @@ -24,28 +24,108 @@ #define SDW_LINK_BASE 0x30000 #define SDW_LINK_SIZE 0x10000

+static void intel_link_dev_release(struct device *dev) +{

• struct auxiliary_device *auxdev = to_auxiliary_dev(dev);
• struct sdw_intel_link_dev *ldev = auxiliary_dev_to_sdw_intel_link_dev(auxdev);
• kfree(ldev);

+}

+/* alloc, init and add link devices */ +static struct sdw_intel_link_dev *intel_link_dev_register(struct sdw_intel_res *res,

• 					  struct sdw_intel_ctx *ctx,
  

• 					  struct fwnode_handle *fwnode,
  

• 					  const char *name,
  

• 					  int link_id)
  

+{

• struct sdw_intel_link_dev *ldev;
• struct sdw_intel_link_res *link;
• struct auxiliary_device *auxdev;
• int ret;
• ldev = kzalloc(sizeof(*ldev), GFP_KERNEL);
• if (!ldev)

• return ERR_PTR(-ENOMEM);
  

• auxdev = &ldev->auxdev;
• auxdev->name = name;
• auxdev->dev.parent = res->parent;
• auxdev->dev.fwnode = fwnode;
• auxdev->dev.release = intel_link_dev_release;
• /* we don't use an IDA since we already have a link ID */
• auxdev->id = link_id;
• /*

• * keep a handle on the allocated memory, to be used in all other functions.
  

• * Since the same pattern is used to skip links that are not enabled, there is
  

• * no need to check if ctx->ldev[i] is NULL later on.
  

• */
  

• ctx->ldev[link_id] = ldev;
• /* Add link information used in the driver probe */
• link = &ldev->link_res;
• link->mmio_base = res->mmio_base;
• link->registers = res->mmio_base + SDW_LINK_BASE

• + (SDW_LINK_SIZE * link_id);
  

• link->shim = res->mmio_base + SDW_SHIM_BASE;
• link->alh = res->mmio_base + SDW_ALH_BASE;
• link->ops = res->ops;
• link->dev = res->dev;
• link->clock_stop_quirks = res->clock_stop_quirks;
• link->shim_lock = &ctx->shim_lock;
• link->shim_mask = &ctx->shim_mask;
• link->link_mask = ctx->link_mask;
• /* now follow the two-step init/add sequence */
• ret = auxiliary_device_init(auxdev);
• if (ret < 0) {

• dev_err(res->parent, "failed to initialize link dev %s link_id %d\n",
  

• 	name, link_id);
  

• kfree(ldev);
  

• return ERR_PTR(ret);
  

• }
• ret = auxiliary_device_add(&ldev->auxdev);
• if (ret < 0) {

• dev_err(res->parent, "failed to add link dev %s link_id %d\n",
  

• 	ldev->auxdev.name, link_id);
  

• /* ldev will be freed with the put_device() and .release sequence */
  

• auxiliary_device_uninit(&ldev->auxdev);
  

• return ERR_PTR(ret);
  

• }
• return ldev;

+}

+static void intel_link_dev_unregister(struct sdw_intel_link_dev *ldev) +{

• auxiliary_device_delete(&ldev->auxdev);
• auxiliary_device_uninit(&ldev->auxdev);

+}

• static int sdw_intel_cleanup(struct sdw_intel_ctx *ctx) {

• struct sdw_intel_link_res *link = ctx->links;

• struct sdw_intel_link_dev *ldev; u32 link_mask; int i;

• if (!link)

• return 0;
  

• link_mask = ctx->link_mask;

• for (i = 0; i < ctx->count; i++, link++) {

• for (i = 0; i < ctx->count; i++) { if (!(link_mask & BIT(i))) continue;

• if (link->pdev) {
  

• 	pm_runtime_disable(&link->pdev->dev);
  

• 	platform_device_unregister(link->pdev);
  

• }
  

• ldev = ctx->ldev[i];
  
  

• if (!link->clock_stop_quirks)
  

• 	pm_runtime_put_noidle(link->dev);
  

• pm_runtime_disable(&ldev->auxdev.dev);
  

• if (!ldev->link_res.clock_stop_quirks)
  

• 	pm_runtime_put_noidle(ldev->link_res.dev);
  

• intel_link_dev_unregister(ldev);
  

  }

  return 0;

@@ -91,9 +171,8 @@ EXPORT_SYMBOL_NS(sdw_intel_thread, SOUNDWIRE_INTEL_INIT); static struct sdw_intel_ctx *sdw_intel_probe_controller(struct sdw_intel_res *res) {

• struct platform_device_info pdevinfo;
• struct platform_device *pdev; struct sdw_intel_link_res *link;

• struct sdw_intel_link_dev *ldev; struct sdw_intel_ctx *ctx; struct acpi_device *adev; struct sdw_slave *slave;

@@ -116,67 +195,60 @@ static struct sdw_intel_ctx count = res->count; dev_dbg(&adev->dev, "Creating %d SDW Link devices\n", count);

• ctx = devm_kzalloc(&adev->dev, sizeof(*ctx), GFP_KERNEL);

• /*

• * we need to alloc/free memory manually and can't use devm:
  

• * this routine may be called from a workqueue, and not from
  

• * the parent .probe.
  

• * If devm_ was used, the memory might never be freed on errors.
  

• */
  

• ctx = kzalloc(sizeof(*ctx), GFP_KERNEL); if (!ctx) return NULL;

  ctx->count = count;

• ctx->links = devm_kcalloc(&adev->dev, ctx->count,

• 		  sizeof(*ctx->links), GFP_KERNEL);
  

• if (!ctx->links)

• /*

• * allocate the array of pointers. The link-specific data is allocated
  

• * as part of the first loop below and released with the auxiliary_device_uninit().
  

• * If some links are disabled, the link pointer will remain NULL. Given that the
  

• * number of links is small, this is simpler than using a list to keep track of links.
  

• */
  

• ctx->ldev = kcalloc(ctx->count, sizeof(*ctx->ldev), GFP_KERNEL);
• if (!ctx->ldev) {

• kfree(ctx);
  

  return NULL;
• }

• ctx->count = count; ctx->mmio_base = res->mmio_base; ctx->link_mask = res->link_mask; ctx->handle = res->handle; mutex_init(&ctx->shim_lock);

• link = ctx->links; link_mask = ctx->link_mask;

  INIT_LIST_HEAD(&ctx->link_list);

• /* Create SDW Master devices */

• for (i = 0; i < count; i++, link++) {

• if (!(link_mask & BIT(i))) {
  

• 	dev_dbg(&adev->dev,
  

• 		"Link %d masked, will not be enabled\n", i);
  

• for (i = 0; i < count; i++) {

• if (!(link_mask & BIT(i)))
  continue;
  

• }
  
  

• 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->ops = res->ops;
  

• link->dev = res->dev;
  

• link->clock_stop_quirks = res->clock_stop_quirks;
  

• link->shim_lock = &ctx->shim_lock;
  

• link->shim_mask = &ctx->shim_mask;
  

• link->link_mask = link_mask;
  

• memset(&pdevinfo, 0, sizeof(pdevinfo));
  

• pdevinfo.parent = res->parent;
  

• pdevinfo.name = "intel-sdw";
  

• pdevinfo.id = i;
  

• pdevinfo.fwnode = acpi_fwnode_handle(adev);
  

• pdevinfo.data = link;
  

• pdevinfo.size_data = sizeof(*link);
  

• pdev = platform_device_register_full(&pdevinfo);
  

• if (IS_ERR(pdev)) {
  

• 	dev_err(&adev->dev,
  

• 		"platform device creation failed: %ld\n",
  

• 		PTR_ERR(pdev));
  

• /*
  

•  * init and add a device for each link
  

•  *
  

•  * The name of the device will be soundwire_intel.link.[i],
  

•  * with the "soundwire_intel" module prefix automatically added
  

•  * by the auxiliary bus core.
  

•  */
  

• ldev = intel_link_dev_register(res,
  

• 			       ctx,
  

• 			       acpi_fwnode_handle(adev),
  

• 			       "link",
  

• 			       i);
  

• if (IS_ERR(ldev))
  goto err;
  

• }
  

• link->pdev = pdev;
  

• link->cdns = platform_get_drvdata(pdev);
  

• link = &ldev->link_res;
  

• link->cdns = dev_get_drvdata(&ldev->auxdev.dev);
  
  

  if (!link->cdns) { dev_err(&adev->dev, "failed to get link->cdns\n");

@@ -194,8 +266,7 @@ static struct sdw_intel_ctx num_slaves++; }

• ctx->ids = devm_kcalloc(&adev->dev, num_slaves,

• 		sizeof(*ctx->ids), GFP_KERNEL);
  

• ctx->ids = kcalloc(num_slaves, sizeof(*ctx->ids), GFP_KERNEL); if (!ctx->ids) goto err;

@@ -213,8 +284,14 @@ static struct sdw_intel_ctx return ctx;

err:

• ctx->count = i;
• sdw_intel_cleanup(ctx);

• while (i--) {

• if (!(link_mask & BIT(i)))
  

• 	continue;
  

• ldev = ctx->ldev[i];
  

• intel_link_dev_unregister(ldev);
  

• }
• kfree(ctx->ldev);
• kfree(ctx); return NULL; }

@@ -222,7 +299,7 @@ static int sdw_intel_startup_controller(struct sdw_intel_ctx *ctx) { struct acpi_device *adev;

• struct sdw_intel_link_res *link;

• struct sdw_intel_link_dev *ldev; u32 caps; u32 link_mask; int i;

@@ -241,27 +318,28 @@ sdw_intel_startup_controller(struct sdw_intel_ctx *ctx) return -EINVAL; }

• if (!ctx->links)

• if (!ctx->ldev) return -EINVAL;

• link = ctx->links; link_mask = ctx->link_mask;

  /* Startup SDW Master devices */

• for (i = 0; i < ctx->count; i++, link++) {

• for (i = 0; i < ctx->count; i++) { if (!(link_mask & BIT(i))) continue;

• intel_master_startup(link->pdev);
  

• ldev = ctx->ldev[i];
  
  

• if (!link->clock_stop_quirks) {
  

• intel_link_startup(&ldev->auxdev);
  

• if (!ldev->link_res.clock_stop_quirks) {
  /*
   * we need to prevent the parent PCI device
   * from entering pm_runtime suspend, so that
   * power rails to the SoundWire IP are not
   * turned off.
   */
  

• 	pm_runtime_get_noresume(link->dev);
  

• 	pm_runtime_get_noresume(ldev->link_res.dev);
  

  } }

@@ -272,8 +350,8 @@ sdw_intel_startup_controller(struct sdw_intel_ctx *ctx)

• sdw_intel_probe() - SoundWire Intel probe routine
• @res: resource data

• • This registers a platform device for each Master handled by the controller,
• • and SoundWire Master and Slave devices will be created by the platform

• • This registers an auxiliary device for each Master handled by the controller,
• • and SoundWire Master and Slave devices will be created by the auxiliary
  • device probe. All the information necessary is stored in the context, and
  • the res argument pointer can be freed after this step.
  • This function will be called after sdw_intel_acpi_scan() by SOF probe.

@@ -306,27 +384,31 @@ EXPORT_SYMBOL_NS(sdw_intel_startup, SOUNDWIRE_INTEL_INIT); void sdw_intel_exit(struct sdw_intel_ctx *ctx) { sdw_intel_cleanup(ctx);

• kfree(ctx->ids);

• kfree(ctx->ldev);

• kfree(ctx); } EXPORT_SYMBOL_NS(sdw_intel_exit, SOUNDWIRE_INTEL_INIT);

  void sdw_intel_process_wakeen_event(struct sdw_intel_ctx *ctx) {

• struct sdw_intel_link_res *link;

• struct sdw_intel_link_dev *ldev; u32 link_mask; int i;

• if (!ctx->links)

• if (!ctx->ldev) return;

• link = ctx->links; link_mask = ctx->link_mask;

  /* Startup SDW Master devices */

• for (i = 0; i < ctx->count; i++, link++) {

• for (i = 0; i < ctx->count; i++) { if (!(link_mask & BIT(i))) continue;

• intel_master_process_wakeen_event(link->pdev);
  

• ldev = ctx->ldev[i];
  

• intel_link_process_wakeen_event(&ldev->auxdev);
  

  } } EXPORT_SYMBOL_NS(sdw_intel_process_wakeen_event, SOUNDWIRE_INTEL_INIT);

diff --git a/include/linux/soundwire/sdw_intel.h b/include/linux/soundwire/sdw_intel.h index 3a5446ac014a..1ebea7764011 100644 --- a/include/linux/soundwire/sdw_intel.h +++ b/include/linux/soundwire/sdw_intel.h @@ -58,7 +58,7 @@ struct sdw_intel_acpi_info { u32 link_mask; };

-struct sdw_intel_link_res; +struct sdw_intel_link_dev;

/* Intel clock-stop/pm_runtime quirk definitions */

@@ -109,7 +109,7 @@ struct sdw_intel_slave_id {

• Controller
• @num_slaves: total number of devices exposed across all enabled links
• @handle: ACPI parent handle

• • @links: information for each link (controller-specific and kept

• • @ldev: information for each link (controller-specific and kept
  • opaque here)
  • @ids: array of slave_id, representing Slaves exposed across all enabled
  • links

@@ -123,7 +123,7 @@ struct sdw_intel_ctx { u32 link_mask; int num_slaves; acpi_handle handle;

• struct sdw_intel_link_res *links;

• struct sdw_intel_link_dev **ldev; struct sdw_intel_slave_id *ids; struct list_head link_list; struct mutex shim_lock; /* lock for access to shared SHIM registers */