[3/8] thunderbolt: debugfs: Implement Gen 4 margining eye selection

Commit Message

Mika Westerberg Oct. 23, 2024, 10:11 a.m. UTC

From: Aapo Vienamo <[e-mail]>

Add a debugfs knob for USB4 Gen 4 margining eye selection. Gen 4 uses
3-level pulse amplitude modulation (PAM3) which changes how margining
measurements are made because PAM3 has two eyes per lane from which
the margins can be measured.

Signed-off-by: Aapo Vienamo <[e-mail]>
Signed-off-by: Mika Westerberg <[e-mail]>
---
 drivers/thunderbolt/debugfs.c | 58 +++++++++++++++++++++++++++++++++++
 drivers/thunderbolt/sb_regs.h |  3 +-
 drivers/thunderbolt/tb.h      |  1 +
 drivers/thunderbolt/usb4.c    |  6 ++--
 4 files changed, 65 insertions(+), 3 deletions(-)

Patch

diff --git a/drivers/thunderbolt/debugfs.c b/drivers/thunderbolt/debugfs.c
index 83721ca069a5..699e1632e3f5 100644
--- a/drivers/thunderbolt/debugfs.c
+++ b/drivers/thunderbolt/debugfs.c
@@ -436,6 +436,8 @@  static ssize_t retimer_sb_regs_write(struct file *file,
  * @time: %true if time margining is used instead of voltage
  * @right_high: %false if left/low margin test is performed, %true if
  *		right/high
+ * @upper_eye: %false if the lower PAM3 eye is used, %true if the upper
+ *	       eye is used
  */
 struct tb_margining {
 	struct tb_port *port;
@@ -462,6 +464,7 @@  struct tb_margining {
 	bool software;
 	bool time;
 	bool right_high;
+	bool upper_eye;
 };
 
 static int margining_modify_error_counter(struct tb_margining *margining,
@@ -1162,6 +1165,7 @@  static int margining_run_write(void *data, u64 val)
 			.time = margining->time,
 			.voltage_time_offset = margining->voltage_time_offset,
 			.right_high = margining->right_high,
+			.upper_eye = margining->upper_eye,
 			.optional_voltage_offset_range = margining->optional_voltage_offset_range,
 		};
 
@@ -1177,6 +1181,7 @@  static int margining_run_write(void *data, u64 val)
 			.lanes = margining->lanes,
 			.time = margining->time,
 			.right_high = margining->right_high,
+			.upper_eye = margining->upper_eye,
 			.optional_voltage_offset_range = margining->optional_voltage_offset_range,
 		};
 
@@ -1464,6 +1469,55 @@  static int margining_margin_show(struct seq_file *s, void *not_used)
 }
 DEBUGFS_ATTR_RW(margining_margin);
 
+static ssize_t margining_eye_write(struct file *file,
+				   const char __user *user_buf,
+				   size_t count, loff_t *ppos)
+{
+	struct seq_file *s = file->private_data;
+	struct tb_port *port = s->private;
+	struct usb4_port *usb4 = port->usb4;
+	struct tb *tb = port->sw->tb;
+	int ret = 0;
+	char *buf;
+
+	buf = validate_and_copy_from_user(user_buf, &count);
+	if (IS_ERR(buf))
+		return PTR_ERR(buf);
+
+	buf[count - 1] = '\0';
+
+	scoped_cond_guard(mutex_intr, ret = -ERESTARTSYS, &tb->lock) {
+		if (!strcmp(buf, "lower"))
+			usb4->margining->upper_eye = false;
+		else if (!strcmp(buf, "upper"))
+			usb4->margining->upper_eye = true;
+		else
+			ret = -EINVAL;
+	}
+
+	free_page((unsigned long)buf);
+	return ret ? ret : count;
+}
+
+static int margining_eye_show(struct seq_file *s, void *not_used)
+{
+	struct tb_port *port = s->private;
+	struct usb4_port *usb4 = port->usb4;
+	struct tb *tb = port->sw->tb;
+
+	scoped_guard(mutex_intr, &tb->lock) {
+		if (usb4->margining->upper_eye)
+			seq_puts(s, "lower [upper]\n");
+		else
+			seq_puts(s, "[lower] upper\n");
+
+		return 0;
+	}
+
+	return -ERESTARTSYS;
+}
+DEBUGFS_ATTR_RW(margining_eye);
+
 static struct tb_margining *margining_alloc(struct tb_port *port,
 					    struct device *dev,
 					    enum usb4_sb_target target,
@@ -1573,6 +1627,10 @@  static struct tb_margining *margining_alloc(struct tb_port *port,
 		debugfs_create_file("dwell_time", DEBUGFS_MODE, dir, margining,
 				    &margining_dwell_time_fops);
 	}
+
+	if (margining->gen >= 4)
+		debugfs_create_file("eye", 0600, dir, port, &margining_eye_fops);
+
 	return margining;
 }
 
diff --git a/drivers/thunderbolt/sb_regs.h b/drivers/thunderbolt/sb_regs.h
index f60b8d90a71a..b7e91b99fefe 100644
--- a/drivers/thunderbolt/sb_regs.h
+++ b/drivers/thunderbolt/sb_regs.h
@@ -83,7 +83,7 @@  enum usb4_sb_opcode {
 
 /* USB4_SB_OPCODE_RUN_HW_LANE_MARGINING */
 #define USB4_MARGIN_HW_TIME			BIT(3)
-#define USB4_MARGIN_HW_RH			BIT(4)
+#define USB4_MARGIN_HW_RHU			BIT(4)
 #define USB4_MARGIN_HW_BER_MASK			GENMASK(9, 5)
 #define USB4_MARGIN_HW_BER_SHIFT		5
 #define USB4_MARGIN_HW_OPT_VOLTAGE		BIT(10)
@@ -106,6 +106,7 @@  enum usb4_sb_opcode {
 #define USB4_MARGIN_SW_OPT_VOLTAGE		BIT(5)
 #define USB4_MARGIN_SW_VT_MASK			GENMASK(12, 6)
 #define USB4_MARGIN_SW_COUNTER_MASK		GENMASK(14, 13)
+#define USB4_MARGIN_SW_UPPER_EYE		BIT(15)
 
 #define USB4_MARGIN_SW_ERR_COUNTER_LANE_0_MASK	GENMASK(3, 0)
 #define USB4_MARGIN_SW_ERR_COUNTER_LANE_1_MASK	GENMASK(7, 4)
diff --git a/drivers/thunderbolt/tb.h b/drivers/thunderbolt/tb.h
index fa7fc9bba70f..ced9be271620 100644
--- a/drivers/thunderbolt/tb.h
+++ b/drivers/thunderbolt/tb.h
@@ -1384,6 +1384,7 @@  struct usb4_port_margining_params {
 	u32 voltage_time_offset;
 	bool optional_voltage_offset_range;
 	bool right_high;
+	bool upper_eye;
 	bool time;
 };
 
diff --git a/drivers/thunderbolt/usb4.c b/drivers/thunderbolt/usb4.c
index 1fb72ff1268e..985f24b044b3 100644
--- a/drivers/thunderbolt/usb4.c
+++ b/drivers/thunderbolt/usb4.c
@@ -1673,8 +1673,8 @@  int usb4_port_hw_margin(struct tb_port *port, enum usb4_sb_target target,
 	val = params->lanes;
 	if (params->time)
 		val |= USB4_MARGIN_HW_TIME;
-	if (params->right_high)
-		val |= USB4_MARGIN_HW_RH;
+	if (params->right_high || params->upper_eye)
+		val |= USB4_MARGIN_HW_RHU;
 	if (params->ber_level)
 		val |= FIELD_PREP(USB4_MARGIN_HW_BER_MASK, params->ber_level);
 	if (params->optional_voltage_offset_range)
@@ -1723,6 +1723,8 @@  int usb4_port_sw_margin(struct tb_port *port, enum usb4_sb_target target,
 		val |= USB4_MARGIN_SW_OPT_VOLTAGE;
 	if (params->right_high)
 		val |= USB4_MARGIN_SW_RH;
+	if (params->upper_eye)
+		val |= USB4_MARGIN_SW_UPPER_EYE;
 	val |= FIELD_PREP(USB4_MARGIN_SW_COUNTER_MASK, params->error_counter);
 	val |= FIELD_PREP(USB4_MARGIN_SW_VT_MASK, params->voltage_time_offset);