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soundwire: bus: allow device number to be unique at system level 

The SoundWire specification allows the device number to be allocated
at will. When a system includes multiple SoundWire links, the device
number scope is limited to the link to which the device is attached.

However, for integration/debug it can be convenient to have a unique
device number across the system. This patch adds a 'dev_num_ida_min'
field at the bus level, which when set will be used to allocate an
IDA.

The allocation happens when a hardware device reports as ATTACHED. If
any error happens during the enumeration, the allocated IDA is not
freed - the device number will be reused if/when the device re-joins
the bus. The IDA is only freed when the Linux device is unregistered.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Rander Wang <rander.wang@intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Link: https://lore.kernel.org/r/20220823045004.2670658-3-yung-chuan.liao@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
This commit is contained in:
Pierre-Louis Bossart 2022-08-23 12:50:03 +08:00 committed by Vinod Koul
parent 88de0a8f48
commit c605610142
2 changed files with 21 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
drivers/soundwire/bus.c
View File

@ -12,6 +12,7 @@
#include "sysfs_local.h"
static DEFINE_IDA(sdw_bus_ida);
static DEFINE_IDA(sdw_peripheral_ida);
static int sdw_get_id(struct sdw_bus *bus)
{
@ -156,9 +157,11 @@ static int sdw_delete_slave(struct device *dev, void *data)
mutex_lock(&bus->bus_lock);
if (slave->dev_num) /* clear dev_num if assigned */
if (slave->dev_num) { /* clear dev_num if assigned */
clear_bit(slave->dev_num, bus->assigned);
if (bus->dev_num_ida_min)
ida_free(&sdw_peripheral_ida, slave->dev_num);
}
list_del_init(&slave->node);
mutex_unlock(&bus->bus_lock);
@ -638,10 +641,18 @@ static int sdw_get_device_num(struct sdw_slave *slave)
{
int bit;
bit = find_first_zero_bit(slave->bus->assigned, SDW_MAX_DEVICES);
if (bit == SDW_MAX_DEVICES) {
bit = -ENODEV;
goto err;
if (slave->bus->dev_num_ida_min) {
bit = ida_alloc_range(&sdw_peripheral_ida,
slave->bus->dev_num_ida_min, SDW_MAX_DEVICES,
GFP_KERNEL);
if (bit < 0)
goto err;
} else {
bit = find_first_zero_bit(slave->bus->assigned, SDW_MAX_DEVICES);
if (bit == SDW_MAX_DEVICES) {
bit = -ENODEV;
goto err;
}
}
/*

4
include/linux/soundwire/sdw.h
View File

@ -889,6 +889,9 @@ struct sdw_master_ops {
* meaningful if multi_link is set. If set to 1, hardware-based
* synchronization will be used even if a stream only uses a single
* SoundWire segment.
* @dev_num_ida_min: if set, defines the minimum values for the IDA
* used to allocate system-unique device numbers. This value needs to be
* identical across all SoundWire bus in the system.
*/
struct sdw_bus {
struct device *dev;
@ -913,6 +916,7 @@ struct sdw_bus {
u32 bank_switch_timeout;
bool multi_link;
int hw_sync_min_links;
int dev_num_ida_min;
};
int sdw_bus_master_add(struct sdw_bus *bus, struct device *parent,