[PATCH 2/2] [v2] serial: 8250: remove obsolete and broken PORT_RSA support

[Arnd Bergmann <arnd@kernel.org>]

From: Arnd Bergmann <arnd@arndb.de>

For all I can tell, the RSA support in the 8250 driver is not functional
and has not been for a long time.

The RSA-DV II/S ISA card[1] was sold by IODATA in the 1990s as a faster
alternative to regular ISA serial ports, and it was discontinued in
2002. Linux support was added by Kiyokazu SUTO in 2000.

The driver defines an I/O port base address of -8 (negative eight),
which should always get refused by request_region on all architectures
for being outside of the valid resource range.

Further, it seems that a patch to setserial would be required in order
to set PORT_RSA when not using autoconfiguration.

This patch removes all code related to the RSA support, with the exception
of the user-visible PORT_RSA definition.

Link: http://translate.google.com/translate?hl=en&sl=ja&u=http://www.iodata.jp/products/network/rsadv2s.htm
Link: https://lore.kernel.org/all/1309211120-2803-6-git-send-email-arnd@arndb.de/
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
v2: rebased my own patch after 15 years
---
 drivers/tty/serial/8250/8250.h          |  17 --
 drivers/tty/serial/8250/8250_core.c     |   6 -
 drivers/tty/serial/8250/8250_platform.c |   4 -
 drivers/tty/serial/8250/8250_port.c     |   8 -
 drivers/tty/serial/8250/8250_rsa.c      | 209 ------------------------
 drivers/tty/serial/8250/Kconfig         |  11 --
 include/uapi/linux/serial_reg.h         |  51 ------
 7 files changed, 306 deletions(-)
 delete mode 100644 drivers/tty/serial/8250/8250_rsa.c

diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h
index 75afeb8c0cef..6225027ed7b4 100644
--- a/drivers/tty/serial/8250/8250.h
+++ b/drivers/tty/serial/8250/8250.h
@@ -126,9 +126,6 @@ void serial8250_isa_init_ports(void);
 
 extern struct platform_device *serial8250_isa_devs;
 
-extern const struct uart_ops *univ8250_port_base_ops;
-extern struct uart_ops univ8250_port_ops;
-
 static inline int serial_in(struct uart_8250_port *up, int offset)
 {
 	return up->port.serial_in(&up->port, offset);
@@ -323,20 +320,6 @@ static inline int serial8250_pnp_init(void) { return 0; }
 static inline void serial8250_pnp_exit(void) { }
 #endif
 
-#ifdef CONFIG_SERIAL_8250_RSA
-void univ8250_rsa_support(struct uart_ops *ops, const struct uart_ops *core_ops);
-void rsa_enable(struct uart_8250_port *up);
-void rsa_disable(struct uart_8250_port *up);
-void rsa_autoconfig(struct uart_8250_port *up);
-void rsa_reset(struct uart_8250_port *up);
-#else
-static inline void univ8250_rsa_support(struct uart_ops *ops, const struct uart_ops *core_ops) { }
-static inline void rsa_enable(struct uart_8250_port *up) {}
-static inline void rsa_disable(struct uart_8250_port *up) {}
-static inline void rsa_autoconfig(struct uart_8250_port *up) {}
-static inline void rsa_reset(struct uart_8250_port *up) {}
-#endif
-
 #ifdef CONFIG_SERIAL_8250_FINTEK
 int fintek_8250_probe(struct uart_8250_port *uart);
 #else
diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index 96c99f0ae683..b9ce22948389 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -307,9 +307,6 @@ static void univ8250_release_irq(struct uart_8250_port *up)
 		serial_unlink_irq_chain(up);
 }
 
-const struct uart_ops *univ8250_port_base_ops;
-struct uart_ops univ8250_port_ops;
-
 static const struct uart_8250_ops univ8250_driver_ops = {
 	.setup_irq	= univ8250_setup_irq,
 	.release_irq	= univ8250_release_irq,
@@ -352,9 +349,6 @@ struct uart_8250_port *serial8250_setup_port(int index)
 	up->port.port_id = index;
 
 	serial8250_init_port(up);
-	if (!univ8250_port_base_ops)
-		univ8250_port_base_ops = up->port.ops;
-	up->port.ops = &univ8250_port_ops;
 
 	timer_setup(&up->timer, serial8250_timeout, 0);
 
diff --git a/drivers/tty/serial/8250/8250_platform.c b/drivers/tty/serial/8250/8250_platform.c
index 8aa769085bfa..1a41a4ac25f8 100644
--- a/drivers/tty/serial/8250/8250_platform.c
+++ b/drivers/tty/serial/8250/8250_platform.c
@@ -73,10 +73,6 @@ static void __init __serial8250_isa_init_ports(void)
 	for (i = 0; i < nr_uarts; i++)
 		serial8250_setup_port(i);
 
-	/* chain base port ops to support Remote Supervisor Adapter */
-	univ8250_port_ops = *univ8250_port_base_ops;
-	univ8250_rsa_support(&univ8250_port_ops, univ8250_port_base_ops);
-
 	for (i = 0; i < ARRAY_SIZE(old_serial_port) && i < nr_uarts; i++) {
 		struct uart_8250_port *up = serial8250_get_port(i);
 		struct uart_port *port = &up->port;
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 3593e7209879..462441237a90 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -1186,8 +1186,6 @@ static void autoconfig(struct uart_8250_port *up)
 		break;
 	}
 
-	rsa_autoconfig(up);
-
 	serial_out(up, UART_LCR, save_lcr);
 
 	port->fifosize = uart_config[up->port.type].fifo_size;
@@ -1199,7 +1197,6 @@ static void autoconfig(struct uart_8250_port *up)
 		/*
 		 * Reset the UART.
 		 */
-		rsa_reset(up);
 		serial8250_out_MCR(up, save_mcr);
 		serial8250_clear_fifos(up);
 		serial_in(up, UART_RX);
@@ -2156,9 +2153,6 @@ static void serial8250_startup_special(struct uart_port *port)
 				UART_DA830_PWREMU_MGMT_URRST |
 				UART_DA830_PWREMU_MGMT_FREE);
 		break;
-	case PORT_RSA:
-		rsa_enable(up);
-		break;
 	}
 }
 
@@ -2450,8 +2444,6 @@ void serial8250_do_shutdown(struct uart_port *port)
 
 	serial8250_clear_fifos(up);
 
-	rsa_disable(up);
-
 	/*
 	 * Read data port to reset things, and then unlink from
 	 * the IRQ chain.
diff --git a/drivers/tty/serial/8250/8250_rsa.c b/drivers/tty/serial/8250/8250_rsa.c
deleted file mode 100644
index da971437e89c..000000000000
--- a/drivers/tty/serial/8250/8250_rsa.c
+++ /dev/null
@@ -1,209 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0+
-
-#include <linux/errno.h>
-#include <linux/ioport.h>
-#include <linux/module.h>
-#include <linux/moduleparam.h>
-
-#include <linux/serial.h>
-#include <linux/serial_8250.h>
-
-#include "8250.h"
-
-#define PORT_RSA_MAX 4
-static unsigned long probe_rsa[PORT_RSA_MAX];
-static unsigned int probe_rsa_count;
-
-static const struct uart_ops *core_port_base_ops;
-
-static int rsa8250_request_resource(struct uart_8250_port *up)
-{
-	struct uart_port *port = &up->port;
-	unsigned long start;
-	unsigned int size;
-
-	if (!uart_iotype_io(port->iotype))
-		return -EINVAL;
-
-	start = UART_RSA_BASE << port->regshift;
-	start += port->iobase;
-	size = 8 << port->regshift;
-
-	if (!request_region(start, size, "serial-rsa"))
-		return -EBUSY;
-	return 0;
-}
-
-static void rsa8250_release_resource(struct uart_8250_port *up)
-{
-	struct uart_port *port = &up->port;
-	unsigned long offset;
-	unsigned int size;
-
-	if (!uart_iotype_io(port->iotype))
-		return;
-
-	offset = UART_RSA_BASE << port->regshift;
-	size = 8 << port->regshift;
-	release_region(port->iobase + offset, size);
-}
-
-static void univ8250_config_port(struct uart_port *port, int flags)
-{
-	struct uart_8250_port *up = up_to_u8250p(port);
-	unsigned int i;
-
-	up->probe &= ~UART_PROBE_RSA;
-	if (port->type == PORT_RSA) {
-		if (rsa8250_request_resource(up) == 0)
-			up->probe |= UART_PROBE_RSA;
-	} else if (flags & UART_CONFIG_TYPE) {
-		for (i = 0; i < probe_rsa_count; i++) {
-			if (probe_rsa[i] == up->port.iobase) {
-				if (rsa8250_request_resource(up) == 0)
-					up->probe |= UART_PROBE_RSA;
-				break;
-			}
-		}
-	}
-
-	core_port_base_ops->config_port(port, flags);
-
-	if (port->type != PORT_RSA && up->probe & UART_PROBE_RSA)
-		rsa8250_release_resource(up);
-}
-
-static int univ8250_request_port(struct uart_port *port)
-{
-	struct uart_8250_port *up = up_to_u8250p(port);
-	int ret;
-
-	ret = core_port_base_ops->request_port(port);
-	if (ret == 0 && port->type == PORT_RSA) {
-		ret = rsa8250_request_resource(up);
-		if (ret < 0)
-			core_port_base_ops->release_port(port);
-	}
-
-	return ret;
-}
-
-static void univ8250_release_port(struct uart_port *port)
-{
-	struct uart_8250_port *up = up_to_u8250p(port);
-
-	if (port->type == PORT_RSA)
-		rsa8250_release_resource(up);
-	core_port_base_ops->release_port(port);
-}
-
-/*
- * It is not allowed to directly reference any symbols from 8250.ko here as
- * that would result in a dependency loop between the 8250.ko and
- * 8250_base.ko modules. This function is called from 8250.ko and is used to
- * break the symbolic dependency cycle. Anything that is needed from 8250.ko
- * has to be passed as pointers to this function which then can adjust those
- * variables on 8250.ko side or store them locally as needed.
- */
-void univ8250_rsa_support(struct uart_ops *ops, const struct uart_ops *core_ops)
-{
-	core_port_base_ops = core_ops;
-	ops->config_port  = univ8250_config_port;
-	ops->request_port = univ8250_request_port;
-	ops->release_port = univ8250_release_port;
-}
-EXPORT_SYMBOL_FOR_MODULES(univ8250_rsa_support, "8250");
-
-module_param_hw_array(probe_rsa, ulong, ioport, &probe_rsa_count, 0444);
-MODULE_PARM_DESC(probe_rsa, "Probe I/O ports for RSA");
-
-/*
- * Attempts to turn on the RSA FIFO.  Returns zero on failure.
- * We set the port uart clock rate if we succeed.
- */
-static int __rsa_enable(struct uart_8250_port *up)
-{
-	unsigned char mode;
-	int result;
-
-	mode = serial_in(up, UART_RSA_MSR);
-	result = mode & UART_RSA_MSR_FIFO;
-
-	if (!result) {
-		serial_out(up, UART_RSA_MSR, mode | UART_RSA_MSR_FIFO);
-		mode = serial_in(up, UART_RSA_MSR);
-		result = mode & UART_RSA_MSR_FIFO;
-	}
-
-	if (result)
-		up->port.uartclk = SERIAL_RSA_BAUD_BASE * 16;
-
-	return result;
-}
-
-/*
- * If this is an RSA port, see if we can kick it up to the higher speed clock.
- */
-void rsa_enable(struct uart_8250_port *up)
-{
-	if (up->port.type != PORT_RSA)
-		return;
-
-	if (up->port.uartclk != SERIAL_RSA_BAUD_BASE * 16) {
-		guard(uart_port_lock_irq)(&up->port);
-		__rsa_enable(up);
-	}
-	if (up->port.uartclk == SERIAL_RSA_BAUD_BASE * 16)
-		serial_out(up, UART_RSA_FRR, 0);
-}
-
-/*
- * Attempts to turn off the RSA FIFO and resets the RSA board back to 115kbps compat mode. It is
- * unknown why interrupts were disabled in here. However, the caller is expected to preserve this
- * behaviour by grabbing the spinlock before calling this function.
- */
-void rsa_disable(struct uart_8250_port *up)
-{
-	unsigned char mode;
-	int result;
-
-	if (up->port.type != PORT_RSA)
-		return;
-
-	if (up->port.uartclk != SERIAL_RSA_BAUD_BASE * 16)
-		return;
-
-	guard(uart_port_lock_irq)(&up->port);
-
-	mode = serial_in(up, UART_RSA_MSR);
-	result = !(mode & UART_RSA_MSR_FIFO);
-
-	if (!result) {
-		serial_out(up, UART_RSA_MSR, mode & ~UART_RSA_MSR_FIFO);
-		mode = serial_in(up, UART_RSA_MSR);
-		result = !(mode & UART_RSA_MSR_FIFO);
-	}
-
-	if (result)
-		up->port.uartclk = SERIAL_RSA_BAUD_BASE_LO * 16;
-}
-
-void rsa_autoconfig(struct uart_8250_port *up)
-{
-	/* Only probe for RSA ports if we got the region. */
-	if (up->port.type != PORT_16550A)
-		return;
-	if (!(up->probe & UART_PROBE_RSA))
-		return;
-
-	if (__rsa_enable(up))
-		up->port.type = PORT_RSA;
-}
-
-void rsa_reset(struct uart_8250_port *up)
-{
-	if (up->port.type != PORT_RSA)
-		return;
-
-	serial_out(up, UART_RSA_FRR, 0);
-}
diff --git a/drivers/tty/serial/8250/Kconfig b/drivers/tty/serial/8250/Kconfig
index 9917b7e1bb26..908fc86852b6 100644
--- a/drivers/tty/serial/8250/Kconfig
+++ b/drivers/tty/serial/8250/Kconfig
@@ -236,17 +236,6 @@ config SERIAL_8250_DETECT_IRQ
 
 	  If unsure, say N.
 
-config SERIAL_8250_RSA
-	bool "Support RSA serial ports"
-	depends on SERIAL_8250_EXTENDED
-	help
-	  Say Y here if you have a IODATA RSA-DV II/S ISA card and
-	  would like to use its >115kbps speeds.
-	  You will need to provide module parameter "probe_rsa", or boot-time
-	  parameter 8250.probe_rsa with I/O addresses of this card then.
-
-	  If you don't have such card, or if unsure, say N.
-
 config SERIAL_8250_MANY_PORTS
 	bool "Support more than 4 legacy serial ports"
 	depends on SERIAL_8250_EXTENDED
diff --git a/include/uapi/linux/serial_reg.h b/include/uapi/linux/serial_reg.h
index 9c987b04e2d0..e4f288b557ca 100644
--- a/include/uapi/linux/serial_reg.h
+++ b/include/uapi/linux/serial_reg.h
@@ -285,57 +285,6 @@
 #define UART_ACR_ICRRD	0x40	/* ICR Read enable */
 #define UART_ACR_ASREN	0x80	/* Additional status enable */
 
-
-
-/*
- * These definitions are for the RSA-DV II/S card, from
- *
- * Kiyokazu SUTO <suto@ks-and-ks.ne.jp>
- */
-
-#define UART_RSA_BASE (-8)
-
-#define UART_RSA_MSR ((UART_RSA_BASE) + 0) /* I/O: Mode Select Register */
-
-#define UART_RSA_MSR_SWAP (1 << 0) /* Swap low/high 8 bytes in I/O port addr */
-#define UART_RSA_MSR_FIFO (1 << 2) /* Enable the external FIFO */
-#define UART_RSA_MSR_FLOW (1 << 3) /* Enable the auto RTS/CTS flow control */
-#define UART_RSA_MSR_ITYP (1 << 4) /* Level (1) / Edge triger (0) */
-
-#define UART_RSA_IER ((UART_RSA_BASE) + 1) /* I/O: Interrupt Enable Register */
-
-#define UART_RSA_IER_Rx_FIFO_H (1 << 0) /* Enable Rx FIFO half full int. */
-#define UART_RSA_IER_Tx_FIFO_H (1 << 1) /* Enable Tx FIFO half full int. */
-#define UART_RSA_IER_Tx_FIFO_E (1 << 2) /* Enable Tx FIFO empty int. */
-#define UART_RSA_IER_Rx_TOUT (1 << 3) /* Enable char receive timeout int */
-#define UART_RSA_IER_TIMER (1 << 4) /* Enable timer interrupt */
-
-#define UART_RSA_SRR ((UART_RSA_BASE) + 2) /* IN: Status Read Register */
-
-#define UART_RSA_SRR_Tx_FIFO_NEMP (1 << 0) /* Tx FIFO is not empty (1) */
-#define UART_RSA_SRR_Tx_FIFO_NHFL (1 << 1) /* Tx FIFO is not half full (1) */
-#define UART_RSA_SRR_Tx_FIFO_NFUL (1 << 2) /* Tx FIFO is not full (1) */
-#define UART_RSA_SRR_Rx_FIFO_NEMP (1 << 3) /* Rx FIFO is not empty (1) */
-#define UART_RSA_SRR_Rx_FIFO_NHFL (1 << 4) /* Rx FIFO is not half full (1) */
-#define UART_RSA_SRR_Rx_FIFO_NFUL (1 << 5) /* Rx FIFO is not full (1) */
-#define UART_RSA_SRR_Rx_TOUT (1 << 6) /* Character reception timeout occurred (1) */
-#define UART_RSA_SRR_TIMER (1 << 7) /* Timer interrupt occurred */
-
-#define UART_RSA_FRR ((UART_RSA_BASE) + 2) /* OUT: FIFO Reset Register */
-
-#define UART_RSA_TIVSR ((UART_RSA_BASE) + 3) /* I/O: Timer Interval Value Set Register */
-
-#define UART_RSA_TCR ((UART_RSA_BASE) + 4) /* OUT: Timer Control Register */
-
-#define UART_RSA_TCR_SWITCH (1 << 0) /* Timer on */
-
-/*
- * The RSA DSV/II board has two fixed clock frequencies.  One is the
- * standard rate, and the other is 8 times faster.
- */
-#define SERIAL_RSA_BAUD_BASE (921600)
-#define SERIAL_RSA_BAUD_BASE_LO (SERIAL_RSA_BAUD_BASE / 8)
-
 /* Extra registers for TI DA8xx/66AK2x */
 #define UART_DA830_PWREMU_MGMT	12
 
-- 
2.53.0