soundwire: qcom: add debugfs entry for soundwire register dump

For debug purposes add an entry in debugfs to dump Qualcomm
SoundWire Controller registers.

Signed-off-by: Srinivas Kandagatla <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

drivers/soundwire/qcom.c

···
 #include <linux/io.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
+#include <linux/debugfs.h>
 #include <linux/of.h>
 #include <linux/of_irq.h>
 #include <linux/of_device.h>
···
 #define SWRM_DP_PORT_HCTRL_BANK(n, m)	(0x1134 + 0x100 * (n - 1) + 0x40 * m)
 #define SWRM_DP_BLOCK_CTRL3_BANK(n, m)	(0x1138 + 0x100 * (n - 1) + 0x40 * m)
 #define SWRM_DIN_DPn_PCM_PORT_CTRL(n)	(0x1054 + 0x100 * (n - 1))
+#define SWR_MSTR_MAX_REG_ADDR		(0x1740)
 
 #define SWRM_DP_PORT_CTRL_EN_CHAN_SHFT				0x18
 #define SWRM_DP_PORT_CTRL_OFFSET2_SHFT				0x10
···
 	struct device *dev;
 	struct regmap *regmap;
 	void __iomem *mmio;
+#ifdef CONFIG_DEBUG_FS
+	struct dentry *debugfs;
+#endif
 	struct completion broadcast;
 	struct completion enumeration;
 	struct work_struct slave_work;
···
 	return 0;
 }
 
+#ifdef CONFIG_DEBUG_FS
+static int swrm_reg_show(struct seq_file *s_file, void *data)
+{
+	struct qcom_swrm_ctrl *swrm = s_file->private;
+	int reg, reg_val;
+
+	for (reg = 0; reg <= SWR_MSTR_MAX_REG_ADDR; reg += 4) {
+		swrm->reg_read(swrm, reg, &reg_val);
+		seq_printf(s_file, "0x%.3x: 0x%.2x\n", reg, reg_val);
+	}
+
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(swrm_reg);
+#endif
+
 static int qcom_swrm_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
···
 	dev_info(dev, "Qualcomm Soundwire controller v%x.%x.%x Registered\n",
 		 (ctrl->version >> 24) & 0xff, (ctrl->version >> 16) & 0xff,
 		 ctrl->version & 0xffff);
+
+#ifdef CONFIG_DEBUG_FS
+	ctrl->debugfs = debugfs_create_dir("qualcomm-sdw", ctrl->bus.debugfs);
+	debugfs_create_file("qualcomm-registers", 0400, ctrl->debugfs, ctrl,
+			    &swrm_reg_fops);
+#endif
 
 	return 0;