soundwire: intel: enable test modes

This patch adds debugfs support to override the Master and Slave data
modes. The settings only take effect prior to a new stream being
prepared/enabled, or on resume.

The test mode can be set to verify data integrity and detect bus
clashes, but can only be used to test capture paths. In this case the
input generated by a Slave source port is replaced by a fixed or
cyclical patterns.
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Reviewed-by: Rander Wang <rander.wang@linux.intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Link: https://lore.kernel.org/r/20200920193207.31241-3-yung-chuan.liao@linux.intel.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/soundwire/intel.c

@@ -262,6 +262,42 @@ static int intel_reg_show(struct seq_file *s_file, void *data)
 }
 DEFINE_SHOW_ATTRIBUTE(intel_reg);
 
+static int intel_set_m_datamode(void *data, u64 value)
+{
+	struct sdw_intel *sdw = data;
+	struct sdw_bus *bus = &sdw->cdns.bus;
+
+	if (value > SDW_PORT_DATA_MODE_STATIC_1)
+		return -EINVAL;
+
+	/* Userspace changed the hardware state behind the kernel's back */
+	add_taint(TAINT_USER, LOCKDEP_STILL_OK);
+
+	bus->params.m_data_mode = value;
+
+	return 0;
+}
+DEFINE_DEBUGFS_ATTRIBUTE(intel_set_m_datamode_fops, NULL,
+			 intel_set_m_datamode, "%llu\n");
+
+static int intel_set_s_datamode(void *data, u64 value)
+{
+	struct sdw_intel *sdw = data;
+	struct sdw_bus *bus = &sdw->cdns.bus;
+
+	if (value > SDW_PORT_DATA_MODE_STATIC_1)
+		return -EINVAL;
+
+	/* Userspace changed the hardware state behind the kernel's back */
+	add_taint(TAINT_USER, LOCKDEP_STILL_OK);
+
+	bus->params.s_data_mode = value;
+
+	return 0;
+}
+DEFINE_DEBUGFS_ATTRIBUTE(intel_set_s_datamode_fops, NULL,
+			 intel_set_s_datamode, "%llu\n");
+
 static void intel_debugfs_init(struct sdw_intel *sdw)
 {
 	struct dentry *root = sdw->cdns.bus.debugfs;
@@ -274,6 +310,12 @@ static void intel_debugfs_init(struct sdw_intel *sdw)
 	debugfs_create_file("intel-registers", 0400, sdw->debugfs, sdw,
 			    &intel_reg_fops);
 
+	debugfs_create_file("intel-m-datamode", 0200, sdw->debugfs, sdw,
+			    &intel_set_m_datamode_fops);
+
+	debugfs_create_file("intel-s-datamode", 0200, sdw->debugfs, sdw,
+			    &intel_set_s_datamode_fops);
+
 	sdw_cdns_debugfs_init(&sdw->cdns, sdw->debugfs);
 }