[RFC PATCH 28/40] soundwire: intel: handle disabled links

Pierre-Louis Bossart
2019-07-25T23:42:48Z

On most hardware platforms, SoundWire interfaces are pin-muxed with
other interfaces (typically DMIC or I2S) and the status of each link
needs to be checked at boot time.

For Intel platforms, the BIOS provides a menu to enable/disable the
links separately, and the information is provided to the OS with an
Intel-specific _DSD property. The same capability will be added to
revisions of the MIPI DisCo specification.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
---
drivers/soundwire/intel.c | 26 ++++++++++++++++++++++----
include/linux/soundwire/sdw.h | 2 ++
2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/drivers/soundwire/intel.c b/drivers/soundwire/intel.c
index 796ac2bc8cea..5947fa8e840b 100644
--- a/drivers/soundwire/intel.c
+++ b/drivers/soundwire/intel.c
@@ -90,6 +90,8 @@
#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,
@@ -922,7 +924,7 @@ static int sdw_master_read_intel_prop(struct sdw_bus *bus)
struct sdw_master_prop *prop = &bus->prop;
struct fwnode_handle *link;
char name[32];
- int nval, i;
+ u32 quirk_mask;

/* Find master handle */
snprintf(name, sizeof(name),
@@ -937,6 +939,14 @@ static int sdw_master_read_intel_prop(struct sdw_bus *bus)
fwnode_property_read_u32(link,
"intel-sdw-ip-clock",
&prop->mclk_freq);
+
+ fwnode_property_read_u32(link,
+ "intel-quirk-mask",
+ &quirk_mask);
+
+ if (quirk_mask & SDW_INTEL_QUIRK_MASK_BUS_DISABLE)
+ prop->hw_disabled = true;
+
return 0;
}

@@ -997,6 +1007,12 @@ static int intel_probe(struct platform_device *pdev)
goto err_master_reg;
}

+ if (sdw->cdns.bus.prop.hw_disabled) {
+ dev_info(&pdev->dev, "SoundWire master %d is disabled, ignoring\n",
+ sdw->cdns.bus.link_id);
+ return 0;
+ }
+
/* Initialize shim and controller */
intel_link_power_up(sdw);
intel_shim_init(sdw);
@@ -1050,9 +1066,11 @@ static int intel_remove(struct platform_device *pdev)

sdw = platform_get_drvdata(pdev);

- intel_debugfs_exit(sdw);
- free_irq(sdw->res->irq, sdw);
- snd_soc_unregister_component(sdw->cdns.dev);
+ if (!sdw->cdns.bus.prop.hw_disabled) {
+ intel_debugfs_exit(sdw);
+ free_irq(sdw->res->irq, sdw);
+ snd_soc_unregister_component(sdw->cdns.dev);
+ }
sdw_delete_bus_master(&sdw->cdns.bus);

return 0;
diff --git a/include/linux/soundwire/sdw.h b/include/linux/soundwire/sdw.h
index c7dfc824be80..f78b076a8782 100644
--- a/include/linux/soundwire/sdw.h
+++ b/include/linux/soundwire/sdw.h
@@ -380,6 +380,7 @@ struct sdw_slave_prop {
* @err_threshold: Number of times that software may retry sending a single
* command
* @mclk_freq: clock reference passed to SoundWire Master, in Hz.
+ * @hw_disabled: if true, the Master is not functional, typically due to pin-mux
*/
struct sdw_master_prop {
u32 revision;
@@ -395,6 +396,7 @@ struct sdw_master_prop {
bool dynamic_frame;
u32 err_threshold;
u32 mclk_freq;
+ bool hw_disabled;
};

int sdw_master_read_prop(struct sdw_bus *bus);
--
2.20.1