linux-kernel - [PATCH v2 10/17] soundwire: cadence: make SSP interval programmable

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Date:   Tue, 17 Mar 2020 11:33:22 -0500
From:   Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
To:     alsa-devel@...a-project.org
Cc:     linux-kernel@...r.kernel.org, tiwai@...e.de, broonie@...nel.org,
        vkoul@...nel.org, gregkh@...uxfoundation.org, jank@...ence.com,
        srinivas.kandagatla@...aro.org, slawomir.blauciak@...el.com,
        Bard liao <yung-chuan.liao@...ux.intel.com>,
        Rander Wang <rander.wang@...ux.intel.com>,
        Ranjani Sridharan <ranjani.sridharan@...ux.intel.com>,
        Hui Wang <hui.wang@...onical.com>,
        Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        Sanyog Kale <sanyog.r.kale@...el.com>
Subject: [PATCH v2 10/17] soundwire: cadence: make SSP interval programmable

In multi-master mode, the IP will only accept SSP intervals with
integer relationships between the frame rate and the gsync frequency.

E.g for a 48kHz frame rate and 4 kHz gsync signal, the SSP interval
can only be 1, 2, 3, 4, 6, 12.

To simplify we only allow one SSP per gsync interval.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
---
 drivers/soundwire/cadence_master.c | 7 ++++---
 drivers/soundwire/cadence_master.h | 3 +++
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/soundwire/cadence_master.c b/drivers/soundwire/cadence_master.c
index fb697ff665f5..773341568d7e 100644
--- a/drivers/soundwire/cadence_master.c
+++ b/drivers/soundwire/cadence_master.c
@@ -183,7 +183,6 @@ MODULE_PARM_DESC(cdns_mcp_int_mask, "Cadence MCP IntMask");
 #define CDNS_PDI_CONFIG_PORT			GENMASK(4, 0)
 
 /* Driver defaults */
-#define CDNS_DEFAULT_SSP_INTERVAL		0x18
 #define CDNS_TX_TIMEOUT				2000
 
 #define CDNS_SCP_RX_FIFOLEVEL			0x2
@@ -1048,6 +1047,7 @@ static void cdns_init_clock_ctrl(struct sdw_cdns *cdns)
 	struct sdw_bus *bus = &cdns->bus;
 	struct sdw_master_prop *prop = &bus->prop;
 	u32 val;
+	u32 ssp_interval;
 	int divider;
 
 	/* Set clock divider */
@@ -1067,8 +1067,9 @@ static void cdns_init_clock_ctrl(struct sdw_cdns *cdns)
 	cdns_writel(cdns, CDNS_MCP_FRAME_SHAPE_INIT, val);
 
 	/* Set SSP interval to default value */
-	cdns_writel(cdns, CDNS_MCP_SSP_CTRL0, CDNS_DEFAULT_SSP_INTERVAL);
-	cdns_writel(cdns, CDNS_MCP_SSP_CTRL1, CDNS_DEFAULT_SSP_INTERVAL);
+	ssp_interval = prop->default_frame_rate / SDW_CADENCE_GSYNC_HZ;
+	cdns_writel(cdns, CDNS_MCP_SSP_CTRL0, ssp_interval);
+	cdns_writel(cdns, CDNS_MCP_SSP_CTRL1, ssp_interval);
 }
 
 /**
diff --git a/drivers/soundwire/cadence_master.h b/drivers/soundwire/cadence_master.h
index e8fa5c7e09f4..b410656f8194 100644
--- a/drivers/soundwire/cadence_master.h
+++ b/drivers/soundwire/cadence_master.h
@@ -5,6 +5,9 @@
 #ifndef __SDW_CADENCE_H
 #define __SDW_CADENCE_H
 
+#define SDW_CADENCE_GSYNC_KHZ		4 /* 4 kHz */
+#define SDW_CADENCE_GSYNC_HZ		(SDW_CADENCE_GSYNC_KHZ * 1000)
+
 /**
  * struct sdw_cdns_pdi: PDI (Physical Data Interface) instance
  *
-- 
2.20.1