Re: [PATCH] soundwire: debugfs: add root-level peripherals table

[Pierre-Louis Bossart <pierre-louis.bossart@linux.dev>]

On 9/2/26 10:18, Bard Liao wrote:
> The table will let user know what peripherals are listed and get the
> detected status by the dev_num.

This sounds useful indeed, but does this need to be in debugfs?

We already have a sysfs entry for every peripheral listed in ACPI. Each
peripheral will have a set of properties extracted from DisCo tables,
could we piggy-back on all this and just expose the dev_num?

> 
> Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
> ---
>  drivers/soundwire/debugfs.c | 72 +++++++++++++++++++++++++++++++++++++
>  1 file changed, 72 insertions(+)
> 
> diff --git a/drivers/soundwire/debugfs.c b/drivers/soundwire/debugfs.c
> index 2905ec19b838..3cc3428df6a4 100644
> --- a/drivers/soundwire/debugfs.c
> +++ b/drivers/soundwire/debugfs.c
> @@ -9,12 +9,82 @@
>  #include <linux/pm_runtime.h>
>  #include <linux/slab.h>
>  #include <linux/soundwire/sdw.h>
> +#include <linux/soundwire/sdw_type.h>
>  #include <linux/soundwire/sdw_registers.h>
>  #include <linux/string_choices.h>
>  #include "bus.h"
>  
>  static struct dentry *sdw_debugfs_root;
>  
> +#define SDW_PERIPH_HEADER_FMT "%-28s %-7s %-16s %-6s %-7s %-8s %-9s %-11s\n"
> +#define SDW_PERIPH_ENTRY_FMT  "%-28s %-7u %#016llx %-6.4x %-7.4x %-8.2x %-9.2x %-11.1x\n"
> +
> +static u64 sdw_slave_addr_from_id(struct sdw_bus *bus,
> +				 const struct sdw_slave_id *id)
> +{
> +	u64 addr = 0;
> +	u8 unique_id = id->unique_id;
> +
> +	if (unique_id == SDW_IGNORED_UNIQUE_ID)
> +		unique_id = 0;
> +
> +	addr |= FIELD_PREP(SDW_DISCO_LINK_ID_MASK, bus->link_id);
> +	addr |= FIELD_PREP(SDW_VERSION_MASK, id->sdw_version);
> +	addr |= FIELD_PREP(SDW_UNIQUE_ID_MASK, unique_id);
> +	addr |= FIELD_PREP(SDW_MFG_ID_MASK, id->mfg_id);
> +	addr |= FIELD_PREP(SDW_PART_ID_MASK, id->part_id);
> +	addr |= FIELD_PREP(SDW_CLASS_ID_MASK, id->class_id);
> +
> +	return addr;
> +}
> +
> +static void sdw_dump_bus_peripherals(struct seq_file *s_file, struct sdw_bus *bus)
> +{
> +	struct sdw_slave *slave;
> +	u64 addr;
> +
> +	seq_printf(s_file, "master-%d-%d\n",
> +		   bus->controller_id, bus->link_id);
> +	seq_printf(s_file, SDW_PERIPH_HEADER_FMT,
> +		   "name", "dev_num", "addr", "mfg_id", "part_id",
> +		   "class_id", "unique_id", "sdw_version");
> +
> +	mutex_lock(&bus->bus_lock);
> +	list_for_each_entry(slave, &bus->slaves, node) {
> +		addr = sdw_slave_addr_from_id(bus, &slave->id);
> +		seq_printf(s_file, SDW_PERIPH_ENTRY_FMT,
> +			   dev_name(&slave->dev), slave->dev_num,
> +			   addr,
> +			   slave->id.mfg_id, slave->id.part_id,
> +			   slave->id.class_id, slave->id.unique_id,
> +			   slave->id.sdw_version);
> +	}
> +	mutex_unlock(&bus->bus_lock);
> +
> +	seq_putc(s_file, '\n');
> +}
> +
> +static int sdw_root_peripherals_dump(struct device *dev, void *data)
> +{
> +	struct sdw_master_device *md;
> +	struct seq_file *s_file = data;
> +
> +	if (dev->type != &sdw_master_type)
> +		return 0;
> +
> +	md = dev_to_sdw_master_device(dev);
> +	sdw_dump_bus_peripherals(s_file, md->bus);
> +
> +	return 0;
> +}
> +
> +static int sdw_root_peripherals_show(struct seq_file *s_file, void *data)
> +{
> +	return bus_for_each_dev(&sdw_bus_type, NULL, s_file,
> +				sdw_root_peripherals_dump);
> +}
> +DEFINE_SHOW_ATTRIBUTE(sdw_root_peripherals);
> +
>  void sdw_bus_debugfs_init(struct sdw_bus *bus)
>  {
>  	char name[16];
> @@ -375,6 +445,8 @@ void sdw_debugfs_init(void)
>  		firmware_file = kstrdup("", GFP_KERNEL);
>  
>  	sdw_debugfs_root = debugfs_create_dir("soundwire", NULL);
> +	debugfs_create_file("peripherals", 0400, sdw_debugfs_root, NULL,
> +			    &sdw_root_peripherals_fops);
>  }
>  
>  void sdw_debugfs_exit(void)