[RFC PATCH 12/14] cxl: Add basic debugging

[Ben Widawsky <ben.widawsky@xxxxxxxxx>]

Provide a standard debug function for use throughout the driver.

Signed-off-by: Ben Widawsky <ben.widawsky@xxxxxxxxx>
---
 drivers/cxl/cxl.h |  3 +++
 drivers/cxl/mem.c | 26 +++++++++++++++++++++++++-
 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index 77c2dee6843c..e5afb89dab0b 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -9,6 +9,9 @@
 #include <linux/bitops.h>
 #include <linux/io.h>
 
+#define cxl_debug(fmt, ...)                                                    \
+	pr_debug("CXL DEBUG: %s: " fmt, __func__, ##__VA_ARGS__)
+
 #define CXL_SET_FIELD(value, field)                                            \
 	({                                                                     \
 		WARN_ON(!FIELD_FIT(field##_MASK, value));                      \
diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c
index a2cea7ac7cc6..6b2f8d3776b5 100644
--- a/drivers/cxl/mem.c
+++ b/drivers/cxl/mem.c
@@ -122,9 +122,12 @@ static int cxl_mem_wait_for_doorbell(struct cxl_mem *cxlm)
 {
 	const int timeout = msecs_to_jiffies(2000);
 	const unsigned long start = jiffies;
+	unsigned long end = start;
 
 	while (cxl_doorbell_busy(cxlm)) {
-		if (time_after(jiffies, start + timeout)) {
+		end = jiffies;
+
+		if (time_after(end, start + timeout)) {
 			/* Check again in case preempted before timeout test */
 			if (!cxl_doorbell_busy(cxlm))
 				break;
@@ -133,6 +136,8 @@ static int cxl_mem_wait_for_doorbell(struct cxl_mem *cxlm)
 		cpu_relax();
 	}
 
+	cxl_debug("Doorbell wait took %dms",
+		  jiffies_to_msecs(end) - jiffies_to_msecs(start));
 	return 0;
 }
 
@@ -180,6 +185,8 @@ static int cxl_mem_mbox_send_cmd(struct cxl_mem *cxlm,
 	}
 
 	/* #4 */
+	cxl_debug("Sending command to %s\n",
+		  dev_driver_string(&cxlm->pdev->dev));
 	cxl_write_mbox_reg32(cxlm, CXLDEV_MB_CTRL_OFFSET,
 			     CXLDEV_MB_CTRL_DOORBELL);
 
@@ -308,6 +315,8 @@ static int cxl_mem_open(struct inode *inode, struct file *file)
 	if (!cxlmd)
 		return -ENXIO;
 
+	cxl_debug("Opened %pD\n", file);
+
 	file->private_data = cxlmd;
 
 	return 0;
@@ -383,6 +392,10 @@ static int handle_mailbox_cmd_from_user(struct cxl_memdev *cxlmd,
 		.size_in = cmd->info.size_in,
 		.size_out = size_out,
 	};
+	cxl_debug("Submitting command for user\n"
+		  "\topcode: %x\n"
+		  "\tsize: %zub/%zub\n",
+		  mbox_cmd.opcode, mbox_cmd.size_in, mbox_cmd.size_out);
 	rc = cxl_mem_mbox_send_cmd(cxlmd->cxlm, &mbox_cmd);
 	cxl_mem_mbox_put(cxlmd->cxlm);
 	if (rc)
@@ -479,6 +492,8 @@ static long cxl_mem_ioctl(struct file *file, unsigned int cmd, unsigned long arg
 		u32 n_commands;
 		int i, j;
 
+		cxl_debug("Query IOCTL\n");
+
 		if (get_user(n_commands, (u32 __user *)arg))
 			return -EFAULT;
 
@@ -511,6 +526,8 @@ static long cxl_mem_ioctl(struct file *file, unsigned int cmd, unsigned long arg
 		struct cxl_mem_command c;
 		int rc;
 
+		cxl_debug("Send IOCTL\n");
+
 		rc = cxl_validate_cmd_from_user(u, &c);
 		if (rc)
 			return rc;
@@ -843,6 +860,13 @@ static int cxl_mem_identify(struct cxl_mem *cxlm)
 
 	id = (struct cxl_mbox_identify *)mbox_cmd.payload;
 
+	cxl_debug("Driver identify command\n"
+		  "\tFirmware Version: %s\n"
+		  "\tTotal Capacity: %llu (%llu persistent)\n"
+		  "\tLSA size: %u\n",
+		  id->fw_revision, id->total_capacity, id->persistent_capacity,
+		  id->lsa_size);
+
 	/*
 	 * TODO: enumerate DPA map, as 'ram' and 'pmem' do not alias.
 	 * For now, only the capacity is exported in sysfs
-- 
2.29.2