linux-kernel - [PATCH v3 04/12] tty: serial: samsung: prepare for different IO types

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Date: Tue,  9 Jan 2024 12:58:06 +0000
From: Tudor Ambarus <tudor.ambarus@...aro.org>
To: peter.griffin@...aro.org,
	krzysztof.kozlowski+dt@...aro.org,
	gregkh@...uxfoundation.org
Cc: mturquette@...libre.com,
	sboyd@...nel.org,
	robh+dt@...nel.org,
	conor+dt@...nel.org,
	andi.shyti@...nel.org,
	alim.akhtar@...sung.com,
	jirislaby@...nel.org,
	s.nawrocki@...sung.com,
	tomasz.figa@...il.com,
	cw00.choi@...sung.com,
	linux-arm-kernel@...ts.infradead.org,
	linux-samsung-soc@...r.kernel.org,
	linux-clk@...r.kernel.org,
	devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-i2c@...r.kernel.org,
	linux-serial@...r.kernel.org,
	andre.draszik@...aro.org,
	kernel-team@...roid.com,
	willmcvicker@...gle.com,
	Tudor Ambarus <tudor.ambarus@...aro.org>
Subject: [PATCH v3 04/12] tty: serial: samsung: prepare for different IO types

GS101's Connectivity Peripheral blocks (peric0/1 blocks) which
include the I3C and USI (I2C, SPI, UART) only allow 32-bit
register accesses. If using 8-bit register accesses, a SError
Interrupt is raised causing the system unusable.

Instead of specifying the reg-io-width = 4 everywhere, for each node,
the requirement should be deduced from the compatible.

Prepare the samsung tty driver to allow IO types different than
UPIO_MEM. ``struct uart_port::iotype`` is an unsigned char where all
its 8 bits are exposed to uapi. We can't make NULL checks on it to
verify if it's set, thus always set it from the driver's data.
Use u8 for the ``iotype`` member of ``struct s3c24xx_uart_info`` to
emphasize that the iotype is an 8 bit mask.

Signed-off-by: Tudor Ambarus <tudor.ambarus@...aro.org>
---
v3:
- reposition the ``iotype`` member of ``struct s3c24xx_uart_info`` so
  that we reduce the struct's memory footprint.
- change ``iotype`` to u8 to emphasize that it's a 8 bit mask and update
  the commit message explaining why.
v2: new patch

 drivers/tty/serial/samsung_tty.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/samsung_tty.c b/drivers/tty/serial/samsung_tty.c
index 66bd6c090ace..ff646cddd3f8 100644
--- a/drivers/tty/serial/samsung_tty.c
+++ b/drivers/tty/serial/samsung_tty.c
@@ -84,6 +84,7 @@ struct s3c24xx_uart_info {
 	unsigned long		clksel_mask;
 	unsigned long		clksel_shift;
 	unsigned long		ucon_mask;
+	u8			iotype;
 
 	/* uart port features */
 
@@ -1742,7 +1743,6 @@ static void s3c24xx_serial_init_port_default(int index) {
 
 	spin_lock_init(&port->lock);
 
-	port->iotype = UPIO_MEM;
 	port->uartclk = 0;
 	port->fifosize = 16;
 	port->flags = UPF_BOOT_AUTOCONF;
@@ -1989,6 +1989,8 @@ static int s3c24xx_serial_probe(struct platform_device *pdev)
 		break;
 	}
 
+	ourport->port.iotype = ourport->info->iotype;
+
 	if (np) {
 		of_property_read_u32(np,
 			"samsung,uart-fifosize", &ourport->port.fifosize);
@@ -2401,6 +2403,7 @@ static const struct s3c24xx_serial_drv_data s3c6400_serial_drv_data = {
 		.name		= "Samsung S3C6400 UART",
 		.type		= TYPE_S3C6400,
 		.port_type	= PORT_S3C6400,
+		.iotype		= UPIO_MEM,
 		.fifosize	= 64,
 		.has_divslot	= 1,
 		.rx_fifomask	= S3C2440_UFSTAT_RXMASK,
@@ -2430,6 +2433,7 @@ static const struct s3c24xx_serial_drv_data s5pv210_serial_drv_data = {
 		.name		= "Samsung S5PV210 UART",
 		.type		= TYPE_S3C6400,
 		.port_type	= PORT_S3C6400,
+		.iotype		= UPIO_MEM,
 		.has_divslot	= 1,
 		.rx_fifomask	= S5PV210_UFSTAT_RXMASK,
 		.rx_fifoshift	= S5PV210_UFSTAT_RXSHIFT,
@@ -2459,6 +2463,7 @@ static const struct s3c24xx_serial_drv_data s5pv210_serial_drv_data = {
 		.name		= "Samsung Exynos UART",	\
 		.type		= TYPE_S3C6400,			\
 		.port_type	= PORT_S3C6400,			\
+		.iotype		= UPIO_MEM,			\
 		.has_divslot	= 1,				\
 		.rx_fifomask	= S5PV210_UFSTAT_RXMASK,	\
 		.rx_fifoshift	= S5PV210_UFSTAT_RXSHIFT,	\
@@ -2519,6 +2524,7 @@ static const struct s3c24xx_serial_drv_data s5l_serial_drv_data = {
 		.name		= "Apple S5L UART",
 		.type		= TYPE_APPLE_S5L,
 		.port_type	= PORT_8250,
+		.iotype		= UPIO_MEM,
 		.fifosize	= 16,
 		.rx_fifomask	= S3C2410_UFSTAT_RXMASK,
 		.rx_fifoshift	= S3C2410_UFSTAT_RXSHIFT,
@@ -2548,6 +2554,7 @@ static const struct s3c24xx_serial_drv_data artpec8_serial_drv_data = {
 		.name		= "Axis ARTPEC-8 UART",
 		.type		= TYPE_S3C6400,
 		.port_type	= PORT_S3C6400,
+		.iotype		= UPIO_MEM,
 		.fifosize	= 64,
 		.has_divslot	= 1,
 		.rx_fifomask	= S5PV210_UFSTAT_RXMASK,
-- 
2.43.0.472.g3155946c3a-goog