MXC: Add AUDMUXv2 register decode to debugfs

Since AUDMUX configuration appears to be one of the common stumbling
blocks for people setting up i.MX audio try to provide some diagnostic
information describing the current setup to assisist people in working
out what's going on.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

arch/arm/plat-mxc/audmux-v2.c

@@ -23,6 +23,7 @@
 #include <linux/err.h>
 #include <linux/io.h>
 #include <linux/clk.h>
+#include <linux/debugfs.h>
 #include <mach/audmux.h>
 #include <mach/hardware.h>
 
@@ -32,6 +33,140 @@ static void __iomem *audmux_base;
 #define MXC_AUDMUX_V2_PTCR(x)		((x) * 8)
 #define MXC_AUDMUX_V2_PDCR(x)		((x) * 8 + 4)
 
+#ifdef CONFIG_DEBUG_FS
+static struct dentry *audmux_debugfs_root;
+
+static int audmux_open_file(struct inode *inode, struct file *file)
+{
+	file->private_data = inode->i_private;
+	return 0;
+}
+
+/* There is an annoying discontinuity in the SSI numbering with regard
+ * to the Linux number of the devices */
+static const char *audmux_port_string(int port)
+{
+	switch (port) {
+	case MX31_AUDMUX_PORT1_SSI0:
+		return "imx-ssi.0";
+	case MX31_AUDMUX_PORT2_SSI1:
+		return "imx-ssi.1";
+	case MX31_AUDMUX_PORT3_SSI_PINS_3:
+		return "SSI3";
+	case MX31_AUDMUX_PORT4_SSI_PINS_4:
+		return "SSI4";
+	case MX31_AUDMUX_PORT5_SSI_PINS_5:
+		return "SSI5";
+	case MX31_AUDMUX_PORT6_SSI_PINS_6:
+		return "SSI6";
+	default:
+		return "UNKNOWN";
+	}
+}
+
+static ssize_t audmux_read_file(struct file *file, char __user *user_buf,
+				size_t count, loff_t *ppos)
+{
+	ssize_t ret;
+	char *buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
+	int port = (int)file->private_data;
+	u32 pdcr, ptcr;
+
+	if (!buf)
+		return -ENOMEM;
+
+	if (audmux_clk)
+		clk_enable(audmux_clk);
+
+	ptcr = readl(audmux_base + MXC_AUDMUX_V2_PTCR(port));
+	pdcr = readl(audmux_base + MXC_AUDMUX_V2_PDCR(port));
+
+	if (audmux_clk)
+		clk_disable(audmux_clk);
+
+	ret = snprintf(buf, PAGE_SIZE, "PDCR: %08x\nPTCR: %08x\n",
+		       pdcr, ptcr);
+
+	if (ptcr & MXC_AUDMUX_V2_PTCR_TFSDIR)
+		ret += snprintf(buf + ret, PAGE_SIZE - ret,
+				"TxFS output from %s, ",
+				audmux_port_string((ptcr >> 27) & 0x7));
+	else
+		ret += snprintf(buf + ret, PAGE_SIZE - ret,
+				"TxFS input, ");
+
+	if (ptcr & MXC_AUDMUX_V2_PTCR_TCLKDIR)
+		ret += snprintf(buf + ret, PAGE_SIZE - ret,
+				"TxClk output from %s",
+				audmux_port_string((ptcr >> 22) & 0x7));
+	else
+		ret += snprintf(buf + ret, PAGE_SIZE - ret,
+				"TxClk input");
+
+	ret += snprintf(buf + ret, PAGE_SIZE - ret, "\n");
+
+	if (ptcr & MXC_AUDMUX_V2_PTCR_SYN) {
+		ret += snprintf(buf + ret, PAGE_SIZE - ret,
+				"Port is symmetric");
+	} else {
+		if (ptcr & MXC_AUDMUX_V2_PTCR_RFSDIR)
+			ret += snprintf(buf + ret, PAGE_SIZE - ret,
+					"RxFS output from %s, ",
+					audmux_port_string((ptcr >> 17) & 0x7));
+		else
+			ret += snprintf(buf + ret, PAGE_SIZE - ret,
+					"RxFS input, ");
+
+		if (ptcr & MXC_AUDMUX_V2_PTCR_RCLKDIR)
+			ret += snprintf(buf + ret, PAGE_SIZE - ret,
+					"RxClk output from %s",
+					audmux_port_string((ptcr >> 12) & 0x7));
+		else
+			ret += snprintf(buf + ret, PAGE_SIZE - ret,
+					"RxClk input");
+	}
+
+	ret += snprintf(buf + ret, PAGE_SIZE - ret,
+			"\nData received from %s\n",
+			audmux_port_string((pdcr >> 13) & 0x7));
+
+	ret = simple_read_from_buffer(user_buf, count, ppos, buf, ret);
+
+	kfree(buf);
+
+	return ret;
+}
+
+static const struct file_operations audmux_debugfs_fops = {
+	.open = audmux_open_file,
+	.read = audmux_read_file,
+};
+
+static void audmux_debugfs_init(void)
+{
+	int i;
+	char buf[20];
+
+	audmux_debugfs_root = debugfs_create_dir("audmux", NULL);
+	if (!audmux_debugfs_root) {
+		pr_warning("Failed to create AUDMUX debugfs root\n");
+		return;
+	}
+
+	for (i = 1; i < 8; i++) {
+		snprintf(buf, sizeof(buf), "ssi%d", i);
+		if (!debugfs_create_file(buf, 0444, audmux_debugfs_root,
+					 (void *)i, &audmux_debugfs_fops))
+			pr_warning("Failed to create AUDMUX port %d debugfs file\n",
+				   i);
+	}
+}
+#else
+static inline void audmux_debugfs_init(void)
+{
+}
+#endif
+
 int mxc_audmux_v2_configure_port(unsigned int port, unsigned int ptcr,
 		unsigned int pdcr)
 {
@@ -68,6 +203,8 @@ static int mxc_audmux_v2_init(void)
 	if (cpu_is_mx31() || cpu_is_mx35())
 		audmux_base = IO_ADDRESS(AUDMUX_BASE_ADDR);
 
+	audmux_debugfs_init();
+
 	return 0;
 }