bb retimer: Use mutex to lock the access to shared NVM

If the BB retimer has a shared NVM we need 40ms delay after releasing
the RESET line to synchronize, load and initialize both the retimers.
On a non-shared NVM we need 20ms delay to load and initialize. In order
to synchronize, instead of 40ms delay this CL uses a MUTEX to lock
the access of another retimer by not releasing the RESET line until the
first retimer completes initialization.

BUG=b:165895649
BRANCH=none
TEST=Tested on volteer(non shared NVM), tglrvpu_ite (shared NVM)
     Retimer is able to initialize (DP, USB, TBT, USB4 are detected)

Change-Id: I709377c2e6401faa26871289143d71665ee516d1
Signed-off-by: Vijay Hiremath <vijay.p.hiremath@intel.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2368223
Reviewed-by: Keith Short <keithshort@chromium.org>

6 files changed, 14 insertions, 21 deletions

diff --git a/board/delbin/board.c b/board/delbin/board.c
index 5d52800439..e72d4487e4 100644
--- a/board/delbin/board.c
+++ b/board/delbin/board.c
@@ -255,7 +255,6 @@ static const struct usb_mux mux_config_p1_usb3 = {
 };
 
 static const struct bb_usb_control bb_p0_control = {
-	.shared_nvm = false,
 	.usb_ls_en_gpio = GPIO_USB_C0_LS_EN,
 	.retimer_rst_gpio = GPIO_USB_C0_RT_RST_ODL,
 };
diff --git a/board/terrador/board.c b/board/terrador/board.c
index 8f9e973e06..3781dfc356 100644
--- a/board/terrador/board.c
+++ b/board/terrador/board.c
@@ -180,7 +180,6 @@ __override void board_cbi_init(void)
 	 */
 	setup_mux();
 	/* Reassign USB_C0_RT_RST_ODL */
-	bb_controls[USBC_PORT_C0].shared_nvm = false;
 	bb_controls[USBC_PORT_C0].usb_ls_en_gpio = GPIO_USB_C0_LS_EN;
 	bb_controls[USBC_PORT_C0].retimer_rst_gpio = GPIO_USB_C0_RT_RST_ODL;
 
diff --git a/board/tglrvpu_ite/board.c b/board/tglrvpu_ite/board.c
index aa4ff77e96..5698761c6a 100644
--- a/board/tglrvpu_ite/board.c
+++ b/board/tglrvpu_ite/board.c
@@ -26,6 +26,9 @@
 #define CPRINTS(format, args...) cprints(CC_COMMAND, format, ## args)
 #define CPRINTF(format, args...) cprintf(CC_COMMAND, format, ## args)
 
+/* Mutex for shared NVM access */
+static struct mutex bb_nvm_mutex;
+
 /* TCPC gpios */
 const struct tcpc_gpio_config_t tcpc_gpios[] = {
 	[TYPE_C_PORT_0] = {
@@ -170,6 +173,13 @@ __override void bb_retimer_power_handle(const struct usb_mux *me, int on_off)
 
 	/* handle retimer's power domain */
 	if (on_off) {
+		/*
+		 * BB retimer NVM can be shared between multiple ports, hence
+		 * lock enabling the retimer until the current retimer request
+		 * is complete.
+		 */
+		mutex_lock(&bb_nvm_mutex);
+
 		gpio_set_level(control->usb_ls_en_gpio, 1);
 		/*
 		 * Tpw, minimum time from VCC to RESET_N de-assertion is 100us.
@@ -182,15 +192,10 @@ __override void bb_retimer_power_handle(const struct usb_mux *me, int on_off)
 		msleep(10);
 		gpio_set_level(force_power_gpio, 1);
 
-		/*
-		 * If BB retimer NVM is shared between multiple ports, allow
-		 * 40ms time for all the retimers to be initialized.
-		 * Else allow 20ms to initialize.
-		 */
-		if (control->shared_nvm)
-			msleep(40);
-		else
-			msleep(20);
+		/* Allow 20ms time for the retimer to be initialized. */
+		msleep(20);
+
+		mutex_unlock(&bb_nvm_mutex);
 	} else {
 		gpio_set_level(force_power_gpio, 0);
 		msleep(1);
diff --git a/board/tglrvpu_ite/board.h b/board/tglrvpu_ite/board.h
index d6d238fdb9..9559d5526d 100644
--- a/board/tglrvpu_ite/board.h
+++ b/board/tglrvpu_ite/board.h
@@ -79,18 +79,10 @@
 #ifdef BOARD_TGLRVPU_ITE
 	#define I2C_PORT0_BB_RETIMER_ADDR	0x42
 	#define I2C_PORT1_BB_RETIMER_ADDR	0x43
-
-	/* BB retimer nvm is shared between port 0 & 1 */
-	#define BB_RETIMER_SHARED_NVM true
 #else /* BOARD_TGLRVPY_ITE */
 	#define I2C_PORT0_BB_RETIMER_ADDR	0x42
 	#define I2C_PORT1_BB_RETIMER_ADDR	0x41
-
-	/* BB retimers have respective nvm for port 0 & 1 */
-	#define BB_RETIMER_SHARED_NVM false
 #endif /* BOARD_TGLRVPU_ITE */
-#define USB_PORT0_BB_RETIMER_SHARED_NVM	BB_RETIMER_SHARED_NVM
-#define USB_PORT1_BB_RETIMER_SHARED_NVM	BB_RETIMER_SHARED_NVM
 
 /* Enabling SOP* communication */
 #define CONFIG_USB_PD_DECODE_SOP
diff --git a/board/todor/board.c b/board/todor/board.c
index ce036ffab2..215725129e 100644
--- a/board/todor/board.c
+++ b/board/todor/board.c
@@ -206,7 +206,6 @@ __override void board_cbi_init(void)
 	 */
 	setup_mux();
 	/* Reassign USB_C0_RT_RST_ODL */
-	bb_controls[USBC_PORT_C0].shared_nvm = false;
 	bb_controls[USBC_PORT_C0].usb_ls_en_gpio = GPIO_USB_C0_LS_EN;
 	bb_controls[USBC_PORT_C0].retimer_rst_gpio = GPIO_USB_C0_RT_RST_ODL;
 
diff --git a/board/voxel/board.c b/board/voxel/board.c
index 66015c522d..a46bf3ee83 100644
--- a/board/voxel/board.c
+++ b/board/voxel/board.c
@@ -236,7 +236,6 @@ __override void board_cbi_init(void)
 	setup_mux();
 
 	/* Reassign USB_C0_RT_RST_ODL */
-	bb_controls[USBC_PORT_C0].shared_nvm = false;
 	bb_controls[USBC_PORT_C0].usb_ls_en_gpio = GPIO_USB_C0_LS_EN;
 	bb_controls[USBC_PORT_C0].retimer_rst_gpio = GPIO_USB_C0_RT_RST_ODL;
 }