[Patch v3 1/4] thunderbolt: Introduce usb4_port_reset() and tb_lc_reset_port()

Sanath S
2024-01-06T16:58:06Z

Introduce the usb4_port_reset() function that performs the DPR
of a given port. This function follows the CM guide specification 7.3

Introduce tb_lc_reset_port() function that performs the DPR through
link control registers. Supports non-USB4 routers like TBT2 and TBT3.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Sanath S <Sanath.S@amd.com>
---
drivers/thunderbolt/lc.c | 44 +++++++++++++++++++++++++++++++++++
drivers/thunderbolt/tb_regs.h | 4 ++++
drivers/thunderbolt/usb4.c | 39 +++++++++++++++++++++++++++++++
3 files changed, 87 insertions(+)

diff --git a/drivers/thunderbolt/lc.c b/drivers/thunderbolt/lc.c
index 633970fbe9b0..de7276909a42 100644
--- a/drivers/thunderbolt/lc.c
+++ b/drivers/thunderbolt/lc.c
@@ -5,6 +5,7 @@
* Copyright (C) 2019, Intel Corporation
* Author: Mika Westerberg <mika.westerberg@linux.intel.com>
*/
+#include <linux/delay.h>

#include "tb.h"

@@ -45,6 +46,49 @@ static int find_port_lc_cap(struct tb_port *port)
return sw->cap_lc + start + phys * size;
}

+/**
+ * tb_lc_reset_port() - Trigger downstream port reset through LC
+ * @port: Port that is reset
+ *
+ * Triggers downstream port reset through link controller registers.
+ * Returns %0 in case of success negative errno otherwise. Only supports
+ * non-USB4 routers with link controller (that's Thunderbolt 2 and
+ * Thunderbolt 3).
+ */
+int tb_lc_reset_port(struct tb_port *port)
+{
+ struct tb_switch *sw = port->sw;
+ int cap, ret;
+ u32 mode;
+
+ if (sw->generation < 2)
+ return -EINVAL;
+
+ cap = find_port_lc_cap(port);
+ if (cap < 0)
+ return cap;
+
+ ret = tb_sw_read(sw, &mode, TB_CFG_SWITCH, cap + TB_LC_PORT_MODE, 1);
+ if (ret)
+ return ret;
+
+ mode |= TB_LC_PORT_MODE_DPR;
+
+ ret = tb_sw_write(sw, &mode, TB_CFG_SWITCH, cap + TB_LC_PORT_MODE, 1);
+ if (ret)
+ return ret;
+
+ fsleep(10000);
+
+ ret = tb_sw_read(sw, &mode, TB_CFG_SWITCH, cap + TB_LC_PORT_MODE, 1);
+ if (ret)
+ return ret;
+
+ mode &= ~TB_LC_PORT_MODE_DPR;
+
+ return tb_sw_write(sw, &mode, TB_CFG_SWITCH, cap + TB_LC_PORT_MODE, 1);
+}
+
static int tb_lc_set_port_configured(struct tb_port *port, bool configured)
{
bool upstream = tb_is_upstream_port(port);
diff --git a/drivers/thunderbolt/tb_regs.h b/drivers/thunderbolt/tb_regs.h
index 87e4795275fe..efcae298b370 100644
--- a/drivers/thunderbolt/tb_regs.h
+++ b/drivers/thunderbolt/tb_regs.h
@@ -389,6 +389,7 @@ struct tb_regs_port_header {
#define PORT_CS_18_CSA BIT(22)
#define PORT_CS_18_TIP BIT(24)
#define PORT_CS_19 0x13
+#define PORT_CS_19_DPR BIT(0)
#define PORT_CS_19_PC BIT(3)
#define PORT_CS_19_PID BIT(4)
#define PORT_CS_19_WOC BIT(16)
@@ -584,6 +585,9 @@ struct tb_regs_hop {
#define TB_LC_POWER 0x740

/* Link controller registers */
+#define TB_LC_PORT_MODE 0x26
+#define TB_LC_PORT_MODE_DPR BIT(0)
+
#define TB_LC_CS_42 0x2a
#define TB_LC_CS_42_USB_PLUGGED BIT(31)

diff --git a/drivers/thunderbolt/usb4.c b/drivers/thunderbolt/usb4.c
index f8f0d24ff6e4..4b35898aa216 100644
--- a/drivers/thunderbolt/usb4.c
+++ b/drivers/thunderbolt/usb4.c
@@ -1113,6 +1113,45 @@ int usb4_port_hotplug_enable(struct tb_port *port)
return tb_port_write(port, &val, TB_CFG_PORT, ADP_CS_5, 1);
}

+/**
+ * usb4_port_reset() - Issue downstream port reset
+ * @port: USB4 port to reset
+ *
+ * Issues downstream port reset to @port.
+ */
+int usb4_port_reset(struct tb_port *port)
+{
+ int ret;
+ u32 val;
+
+ if (!port->cap_usb4)
+ return -EINVAL;
+
+ ret = tb_port_read(port, &val, TB_CFG_PORT,
+ port->cap_usb4 + PORT_CS_19, 1);
+ if (ret)
+ return ret;
+
+ val |= PORT_CS_19_DPR;
+
+ ret = tb_port_write(port, &val, TB_CFG_PORT,
+ port->cap_usb4 + PORT_CS_19, 1);
+ if (ret)
+ return ret;
+
+ fsleep(10000);
+
+ ret = tb_port_read(port, &val, TB_CFG_PORT,
+ port->cap_usb4 + PORT_CS_19, 1);
+ if (ret)
+ return ret;
+
+ val &= ~PORT_CS_19_DPR;
+
+ return tb_port_write(port, &val, TB_CFG_PORT,
+ port->cap_usb4 + PORT_CS_19, 1);
+}
+
static int usb4_port_set_configured(struct tb_port *port, bool configured)
{
int ret;
--
2.34.1