From: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>
The SoundWire 1.2 specification adds new registers to allow for
seamless clock changes while audio transfers are on-going. Program
them following the specification.
Note that dynamic clock changes are not supported for now, this only
adds the register initialization.
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>
Reviewed-by: Kai Vehmanen <kai.vehmanen@xxxxxxxxxxxxxxx>
Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@xxxxxxxxxxxxxxx>
Signed-off-by: Bard Liao <yung-chuan.liao@xxxxxxxxxxxxxxx>
---
drivers/soundwire/bus.c | 107 ++++++++++++++++++++++++
include/linux/soundwire/sdw_registers.h | 10 +++
2 files changed, 117 insertions(+)
diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
index 24ba77226376..83f9d7e0de80 100644
--- a/drivers/soundwire/bus.c
+++ b/drivers/soundwire/bus.c
@@ -1059,12 +1059,119 @@ int sdw_configure_dpn_intr(struct sdw_slave *slave,
return ret;
}
+static int sdw_slave_set_frequency(struct sdw_slave *slave)
+{
+ u32 mclk_freq = slave->bus->prop.mclk_freq;
+ u32 curr_freq = slave->bus->params.curr_dr_freq >> 1;
+ unsigned int scale;
+ u8 scale_index;
+ u8 base;
+ int ret;
+
+ /*
+ * frequency base and scale registers are required for SDCA
+ * devices. They may also be used for 1.2+/non-SDCA devices,
+ * but we will need a DisCo property to cover this case
+ */
+ if (!slave->id.class_id)
+ return 0;
+
+ if (!mclk_freq) {
+ dev_err(&slave->dev,
+ "no bus MCLK, cannot set SDW_SCP_BUS_CLOCK_BASE\n");
+ return -EINVAL;
+ }
+
+ /*
+ * map base frequency using Table 89 of SoundWire 1.2 spec.
+ * The order of the tests just follows the specification, this
+ * is not a selection between possible values or a search for
+ * the best value but just a mapping. Only one case per platform
+ * is relevant.
+ * Some BIOS have inconsistent values for mclk_freq but a
+ * correct root so we force the mclk_freq to avoid variations.
+ */
+ if (!(19200000 % mclk_freq)) {
+ mclk_freq = 19200000;
+ base = SDW_SCP_BASE_CLOCK_19200000_HZ;
+ } else if (!(24000000 % mclk_freq)) {
+ mclk_freq = 24000000;
+ base = SDW_SCP_BASE_CLOCK_24000000_HZ;
+ } else if (!(24576000 % mclk_freq)) {
+ mclk_freq = 24576000;
+ base = SDW_SCP_BASE_CLOCK_24576000_HZ;
+ } else if (!(22579200 % mclk_freq)) {
+ mclk_freq = 22579200;
+ base = SDW_SCP_BASE_CLOCK_22579200_HZ;
+ } else if (!(32000000 % mclk_freq)) {
+ mclk_freq = 32000000;
+ base = SDW_SCP_BASE_CLOCK_32000000_HZ;
+ } else {
+ dev_err(&slave->dev,
+ "Unsupported clock base, mclk %d\n",
+ mclk_freq);
+ return -EINVAL;
+ }
+
+ if (mclk_freq % curr_freq) {
+ dev_err(&slave->dev,
+ "mclk %d is not multiple of bus curr_freq %d\n",
+ mclk_freq, curr_freq);
+ return -EINVAL;
+ }
+
+ scale = mclk_freq / curr_freq;
+
+ /*
+ * map scale to Table 90 of SoundWire 1.2 spec - and check
+ * that the scale is a power of two and maximum 64
+ */
+ scale_index = ilog2(scale);
+
+ if (BIT(scale_index) != scale || scale_index > 6) {
+ dev_err(&slave->dev,
+ "No match found for scale %d, bus mclk %d curr_freq %d\n",
+ scale, mclk_freq, curr_freq);
+ return -EINVAL;
+ }
+ scale_index++;
+
+ ret = sdw_write(slave, SDW_SCP_BUS_CLOCK_BASE, base);
+ if (ret < 0) {
+ dev_err(&slave->dev,
+ "SDW_SCP_BUS_CLOCK_BASE write failed:%d\n", ret);
+ return ret;
+ }
+
+ /* initialize scale for both banks */
+ ret = sdw_write(slave, SDW_SCP_BUSCLOCK_SCALE_B0, scale_index);
+ if (ret < 0) {
+ dev_err(&slave->dev,
+ "SDW_SCP_BUSCLOCK_SCALE_B0 write failed:%d\n", ret);
+ return ret;
+ }
+ ret = sdw_write(slave, SDW_SCP_BUSCLOCK_SCALE_B1, scale_index);
+ if (ret < 0)
+ dev_err(&slave->dev,
+ "SDW_SCP_BUSCLOCK_SCALE_B1 write failed:%d\n", ret);
+
+ dev_dbg(&slave->dev,
+ "Configured bus base %d, scale %d, mclk %d, curr_freq %d\n",
+ base, scale_index, mclk_freq, curr_freq);
+
+ return ret;
+}
+
static int sdw_initialize_slave(struct sdw_slave *slave)
{
struct sdw_slave_prop *prop = &slave->prop;
int ret;
u8 val;
+ ret = sdw_slave_set_frequency(slave);
+ if (ret < 0)
+ return ret;
+
/*
* Set bus clash, parity and SCP implementation
* defined interrupt mask
diff --git a/include/linux/soundwire/sdw_registers.h b/include/linux/soundwire/sdw_registers.h
index 12f9ffc3eb3b..5d3c271af7d1 100644
--- a/include/linux/soundwire/sdw_registers.h
+++ b/include/linux/soundwire/sdw_registers.h
@@ -109,8 +109,18 @@
#define SDW_SCP_KEEPEREN 0x4A
#define SDW_SCP_BANKDELAY 0x4B
#define SDW_SCP_COMMIT 0x4C
+
#define SDW_SCP_BUS_CLOCK_BASE 0x4D
#define SDW_SCP_BASE_CLOCK_FREQ GENMASK(2, 0)
+#define SDW_SCP_BASE_CLOCK_UNKNOWN 0x0
+#define SDW_SCP_BASE_CLOCK_19200000_HZ 0x1
+#define SDW_SCP_BASE_CLOCK_24000000_HZ 0x2
+#define SDW_SCP_BASE_CLOCK_24576000_HZ 0x3
+#define SDW_SCP_BASE_CLOCK_22579200_HZ 0x4
+#define SDW_SCP_BASE_CLOCK_32000000_HZ 0x5
+#define SDW_SCP_BASE_CLOCK_RESERVED 0x6
+#define SDW_SCP_BASE_CLOCK_IMP_DEF 0x7
+
/* 0x4E is not allocated in SoundWire specification 1.2 */
#define SDW_SCP_TESTMODE 0x4F
#define SDW_SCP_DEVID_0 0x50
--
2.17.1
