soundwire: add debugfs support

Add base debugfs mechanism for SoundWire bus by creating soundwire
root and master-N and slave-x hierarchy.

Also add SDW Slave SCP, DP0 and DP-N register debug file.

Registers not implemented will print as "XX"

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>
Link: https://lore.kernel.org/r/20190821185821.12690-2-pierre-louis.bossart@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

1 files changed, 151 insertions, 0 deletions

diff --git a/drivers/soundwire/debugfs.c b/drivers/soundwire/debugfs.c
new file mode 100644
index 000000000000..fb1140e82b86
--- /dev/null
+++ b/drivers/soundwire/debugfs.c
@@ -0,0 +1,151 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright(c) 2017-2019 Intel Corporation.
+
+#include <linux/device.h>
+#include <linux/debugfs.h>
+#include <linux/mod_devicetable.h>
+#include <linux/slab.h>
+#include <linux/soundwire/sdw.h>
+#include <linux/soundwire/sdw_registers.h>
+#include "bus.h"
+
+static struct dentry *sdw_debugfs_root;
+
+void sdw_bus_debugfs_init(struct sdw_bus *bus)
+{
+	char name[16];
+
+	if (!sdw_debugfs_root)
+		return;
+
+	/* create the debugfs master-N */
+	snprintf(name, sizeof(name), "master-%d", bus->link_id);
+	bus->debugfs = debugfs_create_dir(name, sdw_debugfs_root);
+}
+
+void sdw_bus_debugfs_exit(struct sdw_bus *bus)
+{
+	debugfs_remove_recursive(bus->debugfs);
+}
+
+#define RD_BUF (3 * PAGE_SIZE)
+
+static ssize_t sdw_sprintf(struct sdw_slave *slave,
+			   char *buf, size_t pos, unsigned int reg)
+{
+	int value;
+
+	value = sdw_read(slave, reg);
+
+	if (value < 0)
+		return scnprintf(buf + pos, RD_BUF - pos, "%3x\tXX\n", reg);
+	else
+		return scnprintf(buf + pos, RD_BUF - pos,
+				"%3x\t%2x\n", reg, value);
+}
+
+static int sdw_slave_reg_show(struct seq_file *s_file, void *data)
+{
+	struct sdw_slave *slave = s_file->private;
+	char *buf;
+	ssize_t ret;
+	int i, j;
+
+	buf = kzalloc(RD_BUF, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	ret = scnprintf(buf, RD_BUF, "Register  Value\n");
+
+	/* DP0 non-banked registers */
+	ret += scnprintf(buf + ret, RD_BUF - ret, "\nDP0\n");
+	for (i = SDW_DP0_INT; i <= SDW_DP0_PREPARECTRL; i++)
+		ret += sdw_sprintf(slave, buf, ret, i);
+
+	/* DP0 Bank 0 registers */
+	ret += scnprintf(buf + ret, RD_BUF - ret, "Bank0\n");
+	ret += sdw_sprintf(slave, buf, ret, SDW_DP0_CHANNELEN);
+	for (i = SDW_DP0_SAMPLECTRL1; i <= SDW_DP0_LANECTRL; i++)
+		ret += sdw_sprintf(slave, buf, ret, i);
+
+	/* DP0 Bank 1 registers */
+	ret += scnprintf(buf + ret, RD_BUF - ret, "Bank1\n");
+	ret += sdw_sprintf(slave, buf, ret,
+			SDW_DP0_CHANNELEN + SDW_BANK1_OFFSET);
+	for (i = SDW_DP0_SAMPLECTRL1 + SDW_BANK1_OFFSET;
+			i <= SDW_DP0_LANECTRL + SDW_BANK1_OFFSET; i++)
+		ret += sdw_sprintf(slave, buf, ret, i);
+
+	/* SCP registers */
+	ret += scnprintf(buf + ret, RD_BUF - ret, "\nSCP\n");
+	for (i = SDW_SCP_INT1; i <= SDW_SCP_BANKDELAY; i++)
+		ret += sdw_sprintf(slave, buf, ret, i);
+	for (i = SDW_SCP_DEVID_0; i <= SDW_SCP_DEVID_5; i++)
+		ret += sdw_sprintf(slave, buf, ret, i);
+
+	/*
+	 * SCP Bank 0/1 registers are read-only and cannot be
+	 * retrieved from the Slave. The Master typically keeps track
+	 * of the current frame size so the information can be found
+	 * in other places
+	 */
+
+	/* DP1..14 registers */
+	for (i = 1; SDW_VALID_PORT_RANGE(i); i++) {
+
+		/* DPi registers */
+		ret += scnprintf(buf + ret, RD_BUF - ret, "\nDP%d\n", i);
+		for (j = SDW_DPN_INT(i); j <= SDW_DPN_PREPARECTRL(i); j++)
+			ret += sdw_sprintf(slave, buf, ret, j);
+
+		/* DPi Bank0 registers */
+		ret += scnprintf(buf + ret, RD_BUF - ret, "Bank0\n");
+		for (j = SDW_DPN_CHANNELEN_B0(i);
+		     j <= SDW_DPN_LANECTRL_B0(i); j++)
+			ret += sdw_sprintf(slave, buf, ret, j);
+
+		/* DPi Bank1 registers */
+		ret += scnprintf(buf + ret, RD_BUF - ret, "Bank1\n");
+		for (j = SDW_DPN_CHANNELEN_B1(i);
+		     j <= SDW_DPN_LANECTRL_B1(i); j++)
+			ret += sdw_sprintf(slave, buf, ret, j);
+	}
+
+	seq_printf(s_file, "%s", buf);
+	kfree(buf);
+
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(sdw_slave_reg);
+
+void sdw_slave_debugfs_init(struct sdw_slave *slave)
+{
+	struct dentry *master;
+	struct dentry *d;
+	char name[32];
+
+	master = slave->bus->debugfs;
+
+	/* create the debugfs slave-name */
+	snprintf(name, sizeof(name), "%s", dev_name(&slave->dev));
+	d = debugfs_create_dir(name, master);
+
+	debugfs_create_file("registers", 0400, d, slave, &sdw_slave_reg_fops);
+
+	slave->debugfs = d;
+}
+
+void sdw_slave_debugfs_exit(struct sdw_slave *slave)
+{
+	debugfs_remove_recursive(slave->debugfs);
+}
+
+void sdw_debugfs_init(void)
+{
+	sdw_debugfs_root = debugfs_create_dir("soundwire", NULL);
+}
+
+void sdw_debugfs_exit(void)
+{
+	debugfs_remove_recursive(sdw_debugfs_root);
+}