ALSA: hda: intel-nhlt: add intel_nhlt_ssp_mclk_mask()

SOF topologies hard-code the MCLK used for SSP connections. That was a
bad idea in hindsight, this information should really come from BIOS
and/or machine driver.

This patch introduces a helper to scan all SSP endpoints connected to
a codec, and all formats to see what MCLK is used. When BIT(0) of the
mdivc offset if set in the SSP blob, MCLK0 is used, and likewise when
BIT(1) is set MCLK1 is used.

The case where both MCLKs are used is possible but has never been seen
in practice so should be treated as an error by the caller.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Reviewed-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/20220919115350.43104-4-pierre-louis.bossart@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>

include/sound/intel-nhlt.h

@@ -136,6 +136,8 @@ bool intel_nhlt_has_endpoint_type(struct nhlt_acpi_table *nhlt, u8 link_type);
 
 int intel_nhlt_ssp_endpoint_mask(struct nhlt_acpi_table *nhlt, u8 device_type);
 
+int intel_nhlt_ssp_mclk_mask(struct nhlt_acpi_table *nhlt, int ssp_num);
+
 struct nhlt_specific_cfg *
 intel_nhlt_get_endpoint_blob(struct device *dev, struct nhlt_acpi_table *nhlt,
 			     u32 bus_id, u8 link_type, u8 vbps, u8 bps,
@@ -169,6 +171,11 @@ static inline int intel_nhlt_ssp_endpoint_mask(struct nhlt_acpi_table *nhlt, u8
 	return 0;
 }
 
+static inline int intel_nhlt_ssp_mclk_mask(struct nhlt_acpi_table *nhlt, int ssp_num)
+{
+	return 0;
+}
+
 static inline struct nhlt_specific_cfg *
 intel_nhlt_get_endpoint_blob(struct device *dev, struct nhlt_acpi_table *nhlt,
 			     u32 bus_id, u8 link_type, u8 vbps, u8 bps,

sound/hda/intel-nhlt.c

@@ -157,6 +157,85 @@ int intel_nhlt_ssp_endpoint_mask(struct nhlt_acpi_table *nhlt, u8 device_type)
 }
 EXPORT_SYMBOL(intel_nhlt_ssp_endpoint_mask);
 
+#define SSP_BLOB_V1_0_SIZE		84
+#define SSP_BLOB_V1_0_MDIVC_OFFSET	19 /* offset in u32 */
+
+#define SSP_BLOB_V1_5_SIZE		96
+#define SSP_BLOB_V1_5_MDIVC_OFFSET	21 /* offset in u32 */
+#define SSP_BLOB_VER_1_5		0xEE000105
+
+#define SSP_BLOB_V2_0_SIZE		88
+#define SSP_BLOB_V2_0_MDIVC_OFFSET	20 /* offset in u32 */
+#define SSP_BLOB_VER_2_0		0xEE000200
+
+int intel_nhlt_ssp_mclk_mask(struct nhlt_acpi_table *nhlt, int ssp_num)
+{
+	struct nhlt_endpoint *epnt;
+	struct nhlt_fmt *fmt;
+	struct nhlt_fmt_cfg *cfg;
+	int mclk_mask = 0;
+	int i, j;
+
+	if (!nhlt)
+		return 0;
+
+	epnt = (struct nhlt_endpoint *)nhlt->desc;
+	for (i = 0; i < nhlt->endpoint_count; i++) {
+
+		/* we only care about endpoints connected to an audio codec over SSP */
+		if (epnt->linktype == NHLT_LINK_SSP &&
+		    epnt->device_type == NHLT_DEVICE_I2S &&
+		    epnt->virtual_bus_id == ssp_num) {
+
+			fmt = (struct nhlt_fmt *)(epnt->config.caps + epnt->config.size);
+			cfg = fmt->fmt_config;
+
+			/*
+			 * In theory all formats should use the same MCLK but it doesn't hurt to
+			 * double-check that the configuration is consistent
+			 */
+			for (j = 0; j < fmt->fmt_count; j++) {
+				u32 *blob;
+				int mdivc_offset;
+				int size;
+
+				/* first check we have enough data to read the blob type */
+				if (cfg->config.size < 8)
+					return -EINVAL;
+
+				blob = (u32 *)cfg->config.caps;
+
+				if (blob[1] == SSP_BLOB_VER_2_0) {
+					mdivc_offset = SSP_BLOB_V2_0_MDIVC_OFFSET;
+					size = SSP_BLOB_V2_0_SIZE;
+				} else if (blob[1] == SSP_BLOB_VER_1_5) {
+					mdivc_offset = SSP_BLOB_V1_5_MDIVC_OFFSET;
+					size = SSP_BLOB_V1_5_SIZE;
+				} else {
+					mdivc_offset = SSP_BLOB_V1_0_MDIVC_OFFSET;
+					size = SSP_BLOB_V1_0_SIZE;
+				}
+
+				/* make sure we have enough data for the fixed part of the blob */
+				if (cfg->config.size < size)
+					return -EINVAL;
+
+				mclk_mask |=  blob[mdivc_offset] & GENMASK(1, 0);
+
+				cfg = (struct nhlt_fmt_cfg *)(cfg->config.caps + cfg->config.size);
+			}
+		}
+		epnt = (struct nhlt_endpoint *)((u8 *)epnt + epnt->length);
+	}
+
+	/* make sure only one MCLK is used */
+	if (hweight_long(mclk_mask) != 1)
+		return -EINVAL;
+
+	return mclk_mask;
+}
+EXPORT_SYMBOL(intel_nhlt_ssp_mclk_mask);
+
 static struct nhlt_specific_cfg *
 nhlt_get_specific_cfg(struct device *dev, struct nhlt_fmt *fmt, u8 num_ch,
 		      u32 rate, u8 vbps, u8 bps)