[PATCH v3 2/4] soundwire: cadence_master: add debugfs register dump

[Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>]

Add debugfs file to dump the Cadence master registers.

Credits: this patch is based on an earlier internal contribution by
Vinod Koul, Sanyog Kale, Shreyas Nc and Hardik Shah.

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Sanyog Kale <sanyog.r.kale@intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
---
 drivers/soundwire/cadence_master.c | 107 +++++++++++++++++++++++++++++
 drivers/soundwire/cadence_master.h |   4 ++
 2 files changed, 111 insertions(+)

diff --git a/drivers/soundwire/cadence_master.c b/drivers/soundwire/cadence_master.c
index 3338269397dd..dcb698e43c48 100644
--- a/drivers/soundwire/cadence_master.c
+++ b/drivers/soundwire/cadence_master.c
@@ -8,6 +8,7 @@
 
 #include <linux/delay.h>
 #include <linux/device.h>
+#include <linux/debugfs.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/module.h>
@@ -230,6 +231,112 @@ static int cdns_clear_bit(struct sdw_cdns *cdns, int offset, u32 value)
 	return -EAGAIN;
 }
 
+/*
+ * debugfs
+ */
+#ifdef CONFIG_DEBUG_FS
+
+#define RD_BUF (2 * PAGE_SIZE)
+
+static ssize_t cdns_sprintf(struct sdw_cdns *cdns,
+			    char *buf, size_t pos, unsigned int reg)
+{
+	return scnprintf(buf + pos, RD_BUF - pos,
+			 "%4x\t%8x\n", reg, cdns_readl(cdns, reg));
+}
+
+static int cdns_reg_show(struct seq_file *s, void *data)
+{
+	struct sdw_cdns *cdns = s->private;
+	char *buf;
+	ssize_t ret;
+	int num_ports;
+	int i, j;
+
+	buf = kzalloc(RD_BUF, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	ret = scnprintf(buf, RD_BUF, "Register  Value\n");
+	ret += scnprintf(buf + ret, RD_BUF - ret, "\nMCP Registers\n");
+	/* 8 MCP registers */
+	for (i = CDNS_MCP_CONFIG; i <= CDNS_MCP_PHYCTRL; i += sizeof(u32))
+		ret += cdns_sprintf(cdns, buf, ret, i);
+
+	ret += scnprintf(buf + ret, RD_BUF - ret,
+			 "\nStatus & Intr Registers\n");
+	/* 13 Status & Intr registers (offsets 0x70 and 0x74 not defined) */
+	for (i = CDNS_MCP_STAT; i <=  CDNS_MCP_FIFOSTAT; i += sizeof(u32))
+		ret += cdns_sprintf(cdns, buf, ret, i);
+
+	ret += scnprintf(buf + ret, RD_BUF - ret,
+			 "\nSSP & Clk ctrl Registers\n");
+	ret += cdns_sprintf(cdns, buf, ret, CDNS_MCP_SSP_CTRL0);
+	ret += cdns_sprintf(cdns, buf, ret, CDNS_MCP_SSP_CTRL1);
+	ret += cdns_sprintf(cdns, buf, ret, CDNS_MCP_CLK_CTRL0);
+	ret += cdns_sprintf(cdns, buf, ret, CDNS_MCP_CLK_CTRL1);
+
+	ret += scnprintf(buf + ret, RD_BUF - ret,
+			 "\nDPn B0 Registers\n");
+
+	/*
+	 * in sdw_cdns_pdi_init() we filter out the Bulk PDIs,
+	 * so the indices need to be corrected again
+	 */
+	num_ports = cdns->num_ports + CDNS_PCM_PDI_OFFSET;
+
+	for (i = 0; i < num_ports; i++) {
+		ret += scnprintf(buf + ret, RD_BUF - ret,
+				 "\nDP-%d\n", i);
+		for (j = CDNS_DPN_B0_CONFIG(i);
+		     j < CDNS_DPN_B0_ASYNC_CTRL(i); j += sizeof(u32))
+			ret += cdns_sprintf(cdns, buf, ret, j);
+	}
+
+	ret += scnprintf(buf + ret, RD_BUF - ret,
+			 "\nDPn B1 Registers\n");
+	for (i = 0; i < num_ports; i++) {
+		ret += scnprintf(buf + ret, RD_BUF - ret,
+				 "\nDP-%d\n", i);
+
+		for (j = CDNS_DPN_B1_CONFIG(i);
+		     j < CDNS_DPN_B1_ASYNC_CTRL(i); j += sizeof(u32))
+			ret += cdns_sprintf(cdns, buf, ret, j);
+	}
+
+	ret += scnprintf(buf + ret, RD_BUF - ret,
+			 "\nDPn Control Registers\n");
+	for (i = 0; i < num_ports; i++)
+		ret += cdns_sprintf(cdns, buf, ret,
+				CDNS_PORTCTRL + i * CDNS_PORT_OFFSET);
+
+	ret += scnprintf(buf + ret, RD_BUF - ret,
+			 "\nPDIn Config Registers\n");
+
+	/* number of PDI and ports is interchangeable */
+	for (i = 0; i < num_ports; i++)
+		ret += cdns_sprintf(cdns, buf, ret, CDNS_PDI_CONFIG(i));
+
+	seq_printf(s, "%s", buf);
+	kfree(buf);
+
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(cdns_reg);
+
+/**
+ * sdw_cdns_debugfs_init() - Cadence debugfs init
+ * @cdns: Cadence instance
+ * @root: debugfs root
+ */
+void sdw_cdns_debugfs_init(struct sdw_cdns *cdns, struct dentry *root)
+{
+	debugfs_create_file("cdns-registers", 0400, root, cdns, &cdns_reg_fops);
+}
+EXPORT_SYMBOL_GPL(sdw_cdns_debugfs_init);
+
+#endif /* CONFIG_DEBUG_FS */
+
 /*
  * IO Calls
  */
diff --git a/drivers/soundwire/cadence_master.h b/drivers/soundwire/cadence_master.h
index 8254a9e8deb4..0b72b7094735 100644
--- a/drivers/soundwire/cadence_master.h
+++ b/drivers/soundwire/cadence_master.h
@@ -163,6 +163,10 @@ int sdw_cdns_pdi_init(struct sdw_cdns *cdns,
 		      struct sdw_cdns_stream_config config);
 int sdw_cdns_enable_interrupt(struct sdw_cdns *cdns);
 
+#ifdef CONFIG_DEBUG_FS
+void sdw_cdns_debugfs_init(struct sdw_cdns *cdns, struct dentry *root);
+#endif
+
 int sdw_cdns_get_stream(struct sdw_cdns *cdns,
 			struct sdw_cdns_streams *stream,
 			u32 ch, u32 dir);
-- 
2.20.1