ath10k: add register access debugfs interface

Debugfs files reg_addr and reg_val are used for reading and writing to the
firmware (target) registers. reg_addr contains the address to be accessed,
which also needs to be set first, and reg_value is when used for reading and
writing the actual value in ASCII.

To read a value from the firmware register 0x100000:

# echo 0x100000 > reg_addr
# cat reg_value
0x00100000:0x000002d3

To write value 0x2400 to address 0x100000:

# echo 0x100000 > reg_addr
# echo  0x2400 > reg_value
#

Signed-off-by: Yanbo Li <yanbol@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
diff --git a/drivers/net/wireless/ath/ath10k/hif.h b/drivers/net/wireless/ath/ath10k/hif.h
index 30301f5..bad0719 100644
--- a/drivers/net/wireless/ath/ath10k/hif.h
+++ b/drivers/net/wireless/ath/ath10k/hif.h
@@ -20,6 +20,7 @@
 
 #include <linux/kernel.h>
 #include "core.h"
+#include "debug.h"
 
 struct ath10k_hif_sg_item {
 	u16 transfer_id;
@@ -84,6 +85,10 @@
 
 	u16 (*get_free_queue_number)(struct ath10k *ar, u8 pipe_id);
 
+	u32 (*read32)(struct ath10k *ar, u32 address);
+
+	void (*write32)(struct ath10k *ar, u32 address, u32 value);
+
 	/* Power up the device and enter BMI transfer mode for FW download */
 	int (*power_up)(struct ath10k *ar);
 
@@ -187,4 +192,25 @@
 	return ar->hif.ops->resume(ar);
 }
 
+static inline u32 ath10k_hif_read32(struct ath10k *ar, u32 address)
+{
+	if (!ar->hif.ops->read32) {
+		ath10k_warn(ar, "hif read32 not supported\n");
+		return 0xdeaddead;
+	}
+
+	return ar->hif.ops->read32(ar, address);
+}
+
+static inline void ath10k_hif_write32(struct ath10k *ar,
+				      u32 address, u32 data)
+{
+	if (!ar->hif.ops->write32) {
+		ath10k_warn(ar, "hif write32 not supported\n");
+		return;
+	}
+
+	ar->hif.ops->write32(ar, address, data);
+}
+
 #endif /* _HIF_H_ */