Re: [PATCH v2 03/14] soundwire: Add Master registration

[Vinod Koul]

On Thu, Nov 16, 2017 at 04:05:22PM +0000, Srinivas Kandagatla wrote:
> 
> 
> On 10/11/17 11:49, Vinod Koul wrote:
> >A Master registers with SoundWire bus and scans the firmware provided
> >for device description. In this patch we scan the ACPI namespaces and
> >create the SoundWire Slave devices based on the ACPI description
> >
> >Signed-off-by: Sanyog Kale <sanyog.r.kale@xxxxxxxxx>
> >Signed-off-by: Vinod Koul <vinod.koul@xxxxxxxxx>
> >---
> >  drivers/soundwire/Makefile    |   2 +-
> >  drivers/soundwire/bus.c       | 163 +++++++++++++++++++++++++++++++++++++++
> >  drivers/soundwire/bus.h       |  20 +++++
> >  drivers/soundwire/slave.c     | 172 ++++++++++++++++++++++++++++++++++++++++++
> >  include/linux/soundwire/sdw.h |  11 +++
> >  5 files changed, 367 insertions(+), 1 deletion(-)
> >  create mode 100644 drivers/soundwire/bus.c
> >  create mode 100644 drivers/soundwire/slave.c
> >
> >diff --git a/drivers/soundwire/Makefile b/drivers/soundwire/Makefile
> >index d1281def7662..c875e434f8b3 100644
> >--- a/drivers/soundwire/Makefile
> >+++ b/drivers/soundwire/Makefile
> >@@ -3,5 +3,5 @@
> >  #
> >  #Bus Objs
> >-soundwire-bus-objs := bus_type.o
> >+soundwire-bus-objs := bus_type.o bus.o slave.o
> 
> >+
> >+#include <linux/delay.h>
> >+#include <linux/device.h>
> >+#include <linux/pm_runtime.h>
> Does this belong to this patch.

Not really, tahnks for spotting

> 
> >+#include <linux/soundwire/sdw.h>
> >+#include "bus.h"
> >+
> >+/**
> >+ * sdw_add_bus_master: add a bus Master instance
> >+ *
> >+ * @bus: bus instance
> >+ *
> >+ * Initializes the bus instance, read properties and create child
> >+ * devices.
> >+ */
> >+int sdw_add_bus_master(struct sdw_bus *bus)
> >+{
> >+	int ret;
> >+
> >+	if (!bus->dev) {
> >+		pr_err("SoundWire bus has no device");
> >+		return -ENODEV;
> >+	}
> >+
> >+	mutex_init(&bus->bus_lock);
> >+	INIT_LIST_HEAD(&bus->slaves);
> >+
> >+	/*
> >+	 * Enumeration device number and broadcast device number are
> >+	 * not used for assignment so mask these and other higher bits
> >+	 */
> >+
> >+	/* Set higher order bits */
> >+	*bus->assigned = ~GENMASK(SDW_BROADCAST_DEV_NUM, SDW_ENUM_DEV_NUM);
> Can't we use ida for this.
> This would also cut down code added for allocating dev_num.

Device numbers in SoundWire are 0 thru 15 with 0 and 15 having special
meaning so can'r be allocated. Bitmaps give me a nice way to ensure we dont
use those by masking these and above 15... IDR uses bitmap with stuff on top
which maynot be helpful here as I need a number 1 to 14. For a generic, give
me a number IDRs are very useful.

> 
> >+
> >+	/* Set device number and broadcast device number */
> >+	set_bit(SDW_ENUM_DEV_NUM, bus->assigned);
> >+	set_bit(SDW_BROADCAST_DEV_NUM, bus->assigned);
> 
> >+	return 0;
> >+}
> >+EXPORT_SYMBOL(sdw_add_bus_master);
> >+
> >+static int sdw_delete_slave(struct device *dev, void *data)
> >+{
> >+	struct sdw_slave *slave = dev_to_sdw_dev(dev);
> >+	struct sdw_bus *bus = slave->bus;
> >+
> >+	mutex_lock(&bus->bus_lock);
> >+
> >+	if (slave->dev_num) /* clear dev_num if assigned */
> >+		clear_bit(slave->dev_num, bus->assigned);
> >+
> >+	list_del_init(&slave->node);
> >+	mutex_unlock(&bus->bus_lock);
> >+
> >+	device_unregister(dev);
> >+	return 0;
> >+}
> >+
> >+void sdw_delete_bus_master(struct sdw_bus *bus)
> >+{
> >+	device_for_each_child(bus->dev, NULL, sdw_delete_slave);
> >+}
> >+EXPORT_SYMBOL(sdw_delete_bus_master);
> No kerneldoc..??

will add.

> 
> >+
> diff --git a/drivers/soundwire/slave.c b/drivers/soundwire/slave.c
> >new file mode 100644
> >index 000000000000..4bf2a6cf732c
> >--- /dev/null
> >+++ b/drivers/soundwire/slave.c
> 
> >+
> >+#include <linux/acpi.h>
> >+#include <linux/init.h>
> >+#include <linux/soundwire/sdw.h>
> >+#include "bus.h"
> >+
> >+}
> >+
> >+static int sdw_slave_add(struct sdw_bus *bus,
> >+		struct sdw_slave_id *id, struct fwnode_handle *fwnode)
> >+{
> >+	struct sdw_slave *slave;
> >+	int ret;
> >+
> >+	slave = kzalloc(sizeof(*slave), GFP_KERNEL);
> >+	if (!slave)
> >+		return -ENOMEM;
> >+
> >+	/* Initialize data structure */
> >+	memcpy(&slave->id, id, sizeof(*id));
> >+	slave->dev.parent = bus->dev;
> >+	slave->dev.fwnode = fwnode;
> >+
> >+	/* name shall be sdw:link:mfg:part:class:unique */
> >+	dev_set_name(&slave->dev, "sdw:%x:%x:%x:%x:%x",
> >+			bus->link_id, id->mfg_id, id->part_id,
> >+			id->class_id, id->unique_id);
> >+
> >+	slave->dev.release = sdw_slave_release;
> >+	slave->dev.bus = &sdw_bus_type;
> >+	slave->bus = bus;
> >+	slave->status = SDW_SLAVE_UNATTACHED;
> >+	slave->dev_num = 0;
> >+
> >+	mutex_lock(&bus->bus_lock);
> >+	list_add_tail(&slave->node, &bus->slaves);
> >+	mutex_unlock(&bus->bus_lock);
> >+
> >+	ret = device_register(&slave->dev);
> >+	if (ret) {
> >+		dev_err(bus->dev, "Failed to add slave: ret %d\n", ret);
> >+
> >+		/*
> >+		 * On err, don't free but drop ref as this will be freed
> >+		 * when release method is invoked.
> >+		 */
> >+		mutex_lock(&bus->bus_lock);
> >+		list_del(&slave->node);
> >+		mutex_unlock(&bus->bus_lock);
> >+		put_device(&slave->dev);
> >+		return ret;
> 
> remove this line and ..
> >+	}
> >+
> >+	return 0;
> 
> 	return ret;

better :)

> >+#if IS_ENABLED(CONFIG_OF)
> >+int sdw_of_find_slaves(struct sdw_bus *bus)
> >+{
> >+	/* placeholder now, fill on OF support */
> >+	return -ENOTSUPP;
> >+}
> >+#endif
> 
> We should probably remove this dummy function, and add this functionality
> later.

this was kept for people to know how they may add DT support, but yes its
better to remove.

-- 
~Vinod