linux-kernel - [PATCH 2/2] tty: serial: samsung: Fix serial rx on Apple A7-A9 SoCs

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Message-ID: <20240907111431.2970-3-towinchenmi@gmail.com>
Date: Sat,  7 Sep 2024 19:06:45 +0800
From: Nick Chan <towinchenmi@...il.com>
To: Krzysztof Kozlowski <krzk@...nel.org>,
	Alim Akhtar <alim.akhtar@...sung.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jirislaby@...nel.org>,
	linux-arm-kernel@...ts.infradead.org,
	linux-samsung-soc@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-serial@...r.kernel.org
Cc: asahi@...ts.linux.dev,
	Nick Chan <towinchenmi@...il.com>
Subject: [PATCH 2/2] tty: serial: samsung: Fix serial rx on Apple A7-A9 SoCs

Apple's older A7-A9 SoCs seems to use bit 3 in UTRSTAT as RXTO, which is
enabled by bit 11 in UCON.

Access these bits in addition to the original RXTO and RXTO enable bits,
to allow serial rx to function on A7-A9 SoCs. This change does not
appear to affect the A10 SoC and up.

Signed-off-by: Nick Chan <towinchenmi@...il.com>
---
 drivers/tty/serial/samsung_tty.c | 17 ++++++++++++-----
 include/linux/serial_s3c.h       | 18 +++++++++++-------
 2 files changed, 23 insertions(+), 12 deletions(-)

diff --git a/drivers/tty/serial/samsung_tty.c b/drivers/tty/serial/samsung_tty.c
index 27b8a50bd3e7..f57c5664c098 100644
--- a/drivers/tty/serial/samsung_tty.c
+++ b/drivers/tty/serial/samsung_tty.c
@@ -550,6 +550,7 @@ static void s3c24xx_serial_stop_rx(struct uart_port *port)
 		case TYPE_APPLE_S5L:
 			s3c24xx_clear_bit(port, APPLE_S5L_UCON_RXTHRESH_ENA, S3C2410_UCON);
 			s3c24xx_clear_bit(port, APPLE_S5L_UCON_RXTO_ENA, S3C2410_UCON);
+			s3c24xx_clear_bit(port, APPLE_S5L_UCON_RXTO_LEGACY_ENA, S3C2410_UCON);
 			break;
 		default:
 			disable_irq_nosync(ourport->rx_irq);
@@ -963,9 +964,11 @@ static irqreturn_t apple_serial_handle_irq(int irq, void *id)
 	u32 pend = rd_regl(port, S3C2410_UTRSTAT);
 	irqreturn_t ret = IRQ_NONE;
 
-	if (pend & (APPLE_S5L_UTRSTAT_RXTHRESH | APPLE_S5L_UTRSTAT_RXTO)) {
+	if (pend & (APPLE_S5L_UTRSTAT_RXTHRESH | APPLE_S5L_UTRSTAT_RXTO |
+		APPLE_S5L_UTRSTAT_RXTO_LEGACY)) {
 		wr_regl(port, S3C2410_UTRSTAT,
-			APPLE_S5L_UTRSTAT_RXTHRESH | APPLE_S5L_UTRSTAT_RXTO);
+			APPLE_S5L_UTRSTAT_RXTHRESH | APPLE_S5L_UTRSTAT_RXTO |
+			APPLE_S5L_UTRSTAT_RXTO_LEGACY);
 		ret = s3c24xx_serial_rx_irq(ourport);
 	}
 	if (pend & APPLE_S5L_UTRSTAT_TXTHRESH) {
@@ -1190,7 +1193,8 @@ static void apple_s5l_serial_shutdown(struct uart_port *port)
 	ucon = rd_regl(port, S3C2410_UCON);
 	ucon &= ~(APPLE_S5L_UCON_TXTHRESH_ENA_MSK |
 		  APPLE_S5L_UCON_RXTHRESH_ENA_MSK |
-		  APPLE_S5L_UCON_RXTO_ENA_MSK);
+		  APPLE_S5L_UCON_RXTO_ENA_MSK |
+		  APPLE_S5L_UCON_RXTO_LEGACY_ENA_MSK);
 	wr_regl(port, S3C2410_UCON, ucon);
 
 	wr_regl(port, S3C2410_UTRSTAT, APPLE_S5L_UTRSTAT_ALL_FLAGS);
@@ -1287,6 +1291,7 @@ static int apple_s5l_serial_startup(struct uart_port *port)
 	/* Enable Rx Interrupt */
 	s3c24xx_set_bit(port, APPLE_S5L_UCON_RXTHRESH_ENA, S3C2410_UCON);
 	s3c24xx_set_bit(port, APPLE_S5L_UCON_RXTO_ENA, S3C2410_UCON);
+	s3c24xx_set_bit(port, APPLE_S5L_UCON_RXTO_LEGACY_ENA, S3C2410_UCON);
 
 	return ret;
 }
@@ -2143,13 +2148,15 @@ static int s3c24xx_serial_resume_noirq(struct device *dev)
 
 			ucon &= ~(APPLE_S5L_UCON_TXTHRESH_ENA_MSK |
 				  APPLE_S5L_UCON_RXTHRESH_ENA_MSK |
-				  APPLE_S5L_UCON_RXTO_ENA_MSK);
+				  APPLE_S5L_UCON_RXTO_ENA_MSK |
+				  APPLE_S5L_UCON_RXTO_LEGACY_ENA_MSK);
 
 			if (ourport->tx_enabled)
 				ucon |= APPLE_S5L_UCON_TXTHRESH_ENA_MSK;
 			if (ourport->rx_enabled)
 				ucon |= APPLE_S5L_UCON_RXTHRESH_ENA_MSK |
-					APPLE_S5L_UCON_RXTO_ENA_MSK;
+					APPLE_S5L_UCON_RXTO_ENA_MSK |
+					APPLE_S5L_UCON_RXTO_LEGACY_ENA_MSK;
 
 			wr_regl(port, S3C2410_UCON, ucon);
 
diff --git a/include/linux/serial_s3c.h b/include/linux/serial_s3c.h
index 1672cf0810ef..849d502d348d 100644
--- a/include/linux/serial_s3c.h
+++ b/include/linux/serial_s3c.h
@@ -246,24 +246,28 @@
 				 S5PV210_UFCON_TXTRIG4 |	\
 				 S5PV210_UFCON_RXTRIG4)
 
-#define APPLE_S5L_UCON_RXTO_ENA		9
-#define APPLE_S5L_UCON_RXTHRESH_ENA	12
-#define APPLE_S5L_UCON_TXTHRESH_ENA	13
-#define APPLE_S5L_UCON_RXTO_ENA_MSK	(1 << APPLE_S5L_UCON_RXTO_ENA)
-#define APPLE_S5L_UCON_RXTHRESH_ENA_MSK	(1 << APPLE_S5L_UCON_RXTHRESH_ENA)
-#define APPLE_S5L_UCON_TXTHRESH_ENA_MSK	(1 << APPLE_S5L_UCON_TXTHRESH_ENA)
+#define APPLE_S5L_UCON_RXTO_ENA			9
+#define APPLE_S5L_UCON_RXTO_LEGACY_ENA		11
+#define APPLE_S5L_UCON_RXTHRESH_ENA		12
+#define APPLE_S5L_UCON_TXTHRESH_ENA		13
+#define APPLE_S5L_UCON_RXTO_ENA_MSK		(1 << APPLE_S5L_UCON_RXTO_ENA)
+#define APPLE_S5L_UCON_RXTO_LEGACY_ENA_MSK	(1 << APPLE_S5L_UCON_RXTO_LEGACY_ENA)
+#define APPLE_S5L_UCON_RXTHRESH_ENA_MSK		(1 << APPLE_S5L_UCON_RXTHRESH_ENA)
+#define APPLE_S5L_UCON_TXTHRESH_ENA_MSK		(1 << APPLE_S5L_UCON_TXTHRESH_ENA)
 
 #define APPLE_S5L_UCON_DEFAULT		(S3C2410_UCON_TXIRQMODE | \
 					 S3C2410_UCON_RXIRQMODE | \
 					 S3C2410_UCON_RXFIFO_TOI)
 #define APPLE_S5L_UCON_MASK		(APPLE_S5L_UCON_RXTO_ENA_MSK | \
+					 APPLE_S5L_UCON_RXTO_LEGACY_ENA_MSK | \
 					 APPLE_S5L_UCON_RXTHRESH_ENA_MSK | \
 					 APPLE_S5L_UCON_TXTHRESH_ENA_MSK)
 
+#define APPLE_S5L_UTRSTAT_RXTO_LEGACY	(1<<3)
 #define APPLE_S5L_UTRSTAT_RXTHRESH	(1<<4)
 #define APPLE_S5L_UTRSTAT_TXTHRESH	(1<<5)
 #define APPLE_S5L_UTRSTAT_RXTO		(1<<9)
-#define APPLE_S5L_UTRSTAT_ALL_FLAGS	(0x3f0)
+#define APPLE_S5L_UTRSTAT_ALL_FLAGS	(0x3f8)
 
 #ifndef __ASSEMBLY__
 
-- 
2.46.0