soundwire: intel_init: add checks on link numbers

Add mask to correctly read the SoundWire SHIM LCAP register. Only bits
2..0 are meaningful, the rest is about link synchronization and stream
channel mapping. Without this mask, the hardware information would
always be larger than whatever the BIOS would report.

Also trap the case with zero links.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>

diff --git a/drivers/soundwire/intel_init.c b/drivers/soundwire/intel_init.c
index 771a53a..70637a0 100644 (file)
--- a/drivers/soundwire/intel_init.c
+++ b/drivers/soundwire/intel_init.c
@@ -81,6 +81,7 @@ static struct sdw_intel_ctx
 
        /* Check SNDWLCAP.LCOUNT */
        caps = ioread32(res->mmio_base + SDW_SHIM_BASE + SDW_SHIM_LCAP);
+       caps &= GENMASK(2, 0);
 
        /* Check HW supported vs property value and use min of two */
        count = min_t(u8, caps, count);
@@ -90,6 +91,9 @@ static struct sdw_intel_ctx
                dev_err(&adev->dev, "Link count %d exceeds max %d\n",
                        count, SDW_MAX_LINKS);
                return NULL;
+       } else if (!count) {
+               dev_warn(&adev->dev, "No SoundWire links detected\n");
+               return NULL;
        }
 
        dev_dbg(&adev->dev, "Creating %d SDW Link devices\n", count);