[PATCH v4 0/6] serial: Separate RT288x/Au1xxx code into own file

[PATCH v4 0/6] serial: Separate RT288x/Au1xxx code into own file

[Ilpo Järvinen]

A non-trivial amount of RT288x/Au1xxx code is encapsulated into
ifdeffery in 8250_port / 8250_early and some if/switch UPIO_AU blocks.
Create a separate file from them and do a few additional cleanups.

I kept the Kconfig entry as bool because the code has somewhat tricky
dependency chain (mips arch code and 8250_of driver).

v4:
- Type changes
	- bugs: unsigned short -> u16
	- use u32 for old_dl too

v3:
- Convert dl_read/write() to take u32 arg + name the args
- Separatate the non-driver datastructure changes & document them better
- Fix build when SERIAL_8250=m + SERIAL_8250_RT288X=y (+note reasoning
  in the commit message for future reference)
- Use u8 for arrays that no longer have < 0 values

v2:
- Define register map array lengths explicitly to avoid creating
  declaration trap.

Ilpo Järvinen (6):
  serial: 8250: Change dl_read/write to handle value as u32
  serial: 8250: Document uart_8250_port's ->dl_read/write()
  serial: 8250: Add dl_read/write, bugs and mapsize into
    plat_serial8250_port
  serial: 8250: RT288x/Au1xxx code away from core
  serial: 8250_rt288x: Name non-standard divisor latch reg
  serial: 8250_rt288x: Remove unnecessary UART_REG_UNMAPPED

 arch/mips/alchemy/common/platform.c     |  10 +-
 drivers/tty/serial/8250/8250.h          |   4 +-
 drivers/tty/serial/8250/8250_core.c     |   4 +
 drivers/tty/serial/8250/8250_early.c    |  21 ----
 drivers/tty/serial/8250/8250_em.c       |   4 +-
 drivers/tty/serial/8250/8250_of.c       |   4 +-
 drivers/tty/serial/8250/8250_port.c     |  84 +--------------
 drivers/tty/serial/8250/8250_pxa.c      |   2 +-
 drivers/tty/serial/8250/8250_rt288x.c   | 136 ++++++++++++++++++++++++
 drivers/tty/serial/8250/8250_uniphier.c |   4 +-
 drivers/tty/serial/8250/Makefile        |   1 +
 drivers/tty/serial/Makefile             |   2 +-
 include/linux/serial_8250.h             |  44 ++++++--
 13 files changed, 201 insertions(+), 119 deletions(-)
 create mode 100644 drivers/tty/serial/8250/8250_rt288x.c

-- 
2.30.2

[PATCH v4 1/6] serial: 8250: Change dl_read/write to handle value as u32

[Ilpo Järvinen]

Divisor latch read/write functions currently handle the value is int.
As the value is related to HW context, u32 makes much more sense than a
signed type.

While at it, name the parameters in the callback signature.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
---
 drivers/tty/serial/8250/8250.h          |  4 ++--
 drivers/tty/serial/8250/8250_em.c       |  4 ++--
 drivers/tty/serial/8250/8250_port.c     | 10 +++++-----
 drivers/tty/serial/8250/8250_pxa.c      |  2 +-
 drivers/tty/serial/8250/8250_uniphier.c |  4 ++--
 include/linux/serial_8250.h             |  4 ++--
 6 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h
index 1e8fe44a7099..5418708f4631 100644
--- a/drivers/tty/serial/8250/8250.h
+++ b/drivers/tty/serial/8250/8250.h
@@ -167,12 +167,12 @@ static unsigned int __maybe_unused serial_icr_read(struct uart_8250_port *up,
 
 void serial8250_clear_and_reinit_fifos(struct uart_8250_port *p);
 
-static inline int serial_dl_read(struct uart_8250_port *up)
+static inline u32 serial_dl_read(struct uart_8250_port *up)
 {
 	return up->dl_read(up);
 }
 
-static inline void serial_dl_write(struct uart_8250_port *up, int value)
+static inline void serial_dl_write(struct uart_8250_port *up, u32 value)
 {
 	up->dl_write(up, value);
 }
diff --git a/drivers/tty/serial/8250/8250_em.c b/drivers/tty/serial/8250/8250_em.c
index 25a9ecf26be6..ef5019e944ea 100644
--- a/drivers/tty/serial/8250/8250_em.c
+++ b/drivers/tty/serial/8250/8250_em.c
@@ -139,12 +139,12 @@ static void serial8250_em_serial_out(struct uart_port *p, int offset, int value)
 	}
 }
 
-static int serial8250_em_serial_dl_read(struct uart_8250_port *up)
+static u32 serial8250_em_serial_dl_read(struct uart_8250_port *up)
 {
 	return serial_in(up, UART_DLL_EM) | serial_in(up, UART_DLM_EM) << 8;
 }
 
-static void serial8250_em_serial_dl_write(struct uart_8250_port *up, int value)
+static void serial8250_em_serial_dl_write(struct uart_8250_port *up, u32 value)
 {
 	serial_out(up, UART_DLL_EM, value & 0xff);
 	serial_out(up, UART_DLM_EM, value >> 8 & 0xff);
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index fe8d79c4ae95..344bd447639b 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -325,7 +325,7 @@ static const struct serial8250_config uart_config[] = {
 };
 
 /* Uart divisor latch read */
-static int default_serial_dl_read(struct uart_8250_port *up)
+static u32 default_serial_dl_read(struct uart_8250_port *up)
 {
 	/* Assign these in pieces to truncate any bits above 7.  */
 	unsigned char dll = serial_in(up, UART_DLL);
@@ -335,7 +335,7 @@ static int default_serial_dl_read(struct uart_8250_port *up)
 }
 
 /* Uart divisor latch write */
-static void default_serial_dl_write(struct uart_8250_port *up, int value)
+static void default_serial_dl_write(struct uart_8250_port *up, u32 value)
 {
 	serial_out(up, UART_DLL, value & 0xff);
 	serial_out(up, UART_DLM, value >> 8 & 0xff);
@@ -389,12 +389,12 @@ void au_serial_out(struct uart_port *p, int offset, int value)
 }
 
 /* Au1x00 haven't got a standard divisor latch */
-static int au_serial_dl_read(struct uart_8250_port *up)
+static u32 au_serial_dl_read(struct uart_8250_port *up)
 {
 	return __raw_readl(up->port.membase + 0x28);
 }
 
-static void au_serial_dl_write(struct uart_8250_port *up, int value)
+static void au_serial_dl_write(struct uart_8250_port *up, u32 value)
 {
 	__raw_writel(value, up->port.membase + 0x28);
 }
@@ -847,7 +847,7 @@ static void disable_rsa(struct uart_8250_port *up)
 static int size_fifo(struct uart_8250_port *up)
 {
 	unsigned char old_fcr, old_mcr, old_lcr;
-	unsigned short old_dl;
+	u32 old_dl;
 	int count;
 
 	old_lcr = serial_in(up, UART_LCR);
diff --git a/drivers/tty/serial/8250/8250_pxa.c b/drivers/tty/serial/8250/8250_pxa.c
index 795e55142d4c..28b341f602c6 100644
--- a/drivers/tty/serial/8250/8250_pxa.c
+++ b/drivers/tty/serial/8250/8250_pxa.c
@@ -60,7 +60,7 @@ static const struct of_device_id serial_pxa_dt_ids[] = {
 MODULE_DEVICE_TABLE(of, serial_pxa_dt_ids);
 
 /* Uart divisor latch write */
-static void serial_pxa_dl_write(struct uart_8250_port *up, int value)
+static void serial_pxa_dl_write(struct uart_8250_port *up, u32 value)
 {
 	unsigned int dll;
 
diff --git a/drivers/tty/serial/8250/8250_uniphier.c b/drivers/tty/serial/8250/8250_uniphier.c
index a2978abab0db..a405155264b1 100644
--- a/drivers/tty/serial/8250/8250_uniphier.c
+++ b/drivers/tty/serial/8250/8250_uniphier.c
@@ -145,12 +145,12 @@ static void uniphier_serial_out(struct uart_port *p, int offset, int value)
  * The divisor latch register exists at different address.
  * Override dl_read/write callbacks.
  */
-static int uniphier_serial_dl_read(struct uart_8250_port *up)
+static u32 uniphier_serial_dl_read(struct uart_8250_port *up)
 {
 	return readl(up->port.membase + UNIPHIER_UART_DLR);
 }
 
-static void uniphier_serial_dl_write(struct uart_8250_port *up, int value)
+static void uniphier_serial_dl_write(struct uart_8250_port *up, u32 value)
 {
 	writel(value, up->port.membase + UNIPHIER_UART_DLR);
 }
diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h
index 6f78f302d272..7b5d558e4e0c 100644
--- a/include/linux/serial_8250.h
+++ b/include/linux/serial_8250.h
@@ -129,8 +129,8 @@ struct uart_8250_port {
 	const struct uart_8250_ops *ops;
 
 	/* 8250 specific callbacks */
-	int			(*dl_read)(struct uart_8250_port *);
-	void			(*dl_write)(struct uart_8250_port *, int);
+	u32			(*dl_read)(struct uart_8250_port *up);
+	void			(*dl_write)(struct uart_8250_port *up, u32 value);
 
 	struct uart_8250_em485 *em485;
 	void			(*rs485_start_tx)(struct uart_8250_port *);
-- 
2.30.2

[PATCH v4 2/6] serial: 8250: Document uart_8250_port's ->dl_read/write()

[Ilpo Järvinen]

Add documentation for the struct uart_8250_port divisor latch function
pointers. Documentation is in kernel doc format but don't enable kernel
doc yet as many other fields remain undocumented.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
---
 include/linux/serial_8250.h | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h
index 7b5d558e4e0c..d64e7bbe1f2f 100644
--- a/include/linux/serial_8250.h
+++ b/include/linux/serial_8250.h
@@ -90,8 +90,17 @@ struct uart_8250_em485 {
  * their own 8250 ports without registering their own
  * platform device.  Using these will make your driver
  * dependent on the 8250 driver.
+ *
+ * @dl_read: ``u32 ()(struct uart_8250_port *port)``
+ *
+ *	UART divisor latch read.
+ *
+ * @dl_write: ``void ()(struct uart_8250_port *port, u32 value)``
+ *
+ *	Write @value into UART divisor latch.
+ *
+ *	Locking: Caller holds port's lock.
  */
-
 struct uart_8250_port {
 	struct uart_port	port;
 	struct timer_list	timer;		/* "no irq" timer */
-- 
2.30.2

[PATCH v4 3/6] serial: 8250: Add dl_read/write, bugs and mapsize into plat_serial8250_port

[Ilpo Järvinen]

Add mapsize, bugs, and divisor latch read/write functions
(->dl_read/write()) into plat_serial8250_port to carry the setup
necessary for RT288x/Au1xxx devices over to uart port.

Document the added members with kerneldoc style but do not enable
kerneldoc yet as there are many fields which remain undocumented.

While at it, convert .bugs in struct uart_8250_port to u16 to match it
with the type used in struct plat_serial8250_port.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
---
 drivers/tty/serial/8250/8250_core.c |  4 ++++
 include/linux/serial_8250.h         | 21 ++++++++++++++++++++-
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index 13bf535eedcd..21b15b130d12 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -822,12 +822,16 @@ static int serial8250_probe(struct platform_device *dev)
 		uart.port.iotype	= p->iotype;
 		uart.port.flags		= p->flags;
 		uart.port.mapbase	= p->mapbase;
+		uart.port.mapsize	= p->mapsize;
 		uart.port.hub6		= p->hub6;
 		uart.port.has_sysrq	= p->has_sysrq;
 		uart.port.private_data	= p->private_data;
 		uart.port.type		= p->type;
+		uart.bugs		= p->bugs;
 		uart.port.serial_in	= p->serial_in;
 		uart.port.serial_out	= p->serial_out;
+		uart.dl_read		= p->dl_read;
+		uart.dl_write		= p->dl_write;
 		uart.port.handle_irq	= p->handle_irq;
 		uart.port.handle_break	= p->handle_break;
 		uart.port.set_termios	= p->set_termios;
diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h
index d64e7bbe1f2f..42fc8f64f48e 100644
--- a/include/linux/serial_8250.h
+++ b/include/linux/serial_8250.h
@@ -11,13 +11,29 @@
 #include <linux/serial_reg.h>
 #include <linux/platform_device.h>
 
+struct uart_8250_port;
+
 /*
  * This is the platform device platform_data structure
+ *
+ * @mapsize:	Port size for ioremap()
+ * @bugs:	Port bugs
+ *
+ * @dl_read: ``u32 ()(struct uart_8250_port *up)``
+ *
+ *	UART divisor latch read.
+ *
+ * @dl_write: ``void ()(struct uart_8250_port *up, u32 value)``
+ *
+ *	Write @value into UART divisor latch.
+ *
+ *	Locking: Caller holds port's lock.
  */
 struct plat_serial8250_port {
 	unsigned long	iobase;		/* io base address */
 	void __iomem	*membase;	/* ioremap cookie or NULL */
 	resource_size_t	mapbase;	/* resource base */
+	resource_size_t	mapsize;
 	unsigned int	uartclk;	/* UART clock rate */
 	unsigned int	irq;		/* interrupt number */
 	unsigned long	irqflags;	/* request_irq flags */
@@ -28,8 +44,11 @@ struct plat_serial8250_port {
 	unsigned char	has_sysrq;	/* supports magic SysRq */
 	unsigned int	type;		/* If UPF_FIXED_TYPE */
 	upf_t		flags;		/* UPF_* flags */
+	u16		bugs;		/* port bugs */
 	unsigned int	(*serial_in)(struct uart_port *, int);
 	void		(*serial_out)(struct uart_port *, int, int);
+	u32		(*dl_read)(struct uart_8250_port *up);
+	void		(*dl_write)(struct uart_8250_port *up, u32 value);
 	void		(*set_termios)(struct uart_port *,
 			               struct ktermios *new,
 			               const struct ktermios *old);
@@ -106,7 +125,7 @@ struct uart_8250_port {
 	struct timer_list	timer;		/* "no irq" timer */
 	struct list_head	list;		/* ports on this IRQ */
 	u32			capabilities;	/* port capabilities */
-	unsigned short		bugs;		/* port bugs */
+	u16			bugs;		/* port bugs */
 	bool			fifo_bug;	/* min RX trigger if enabled */
 	unsigned int		tx_loadsz;	/* transmit fifo load size */
 	unsigned char		acr;
-- 
2.30.2

[PATCH v4 4/6] serial: 8250: RT288x/Au1xxx code away from core

[Ilpo Järvinen]

A non-trivial amount of RT288x/Au1xxx code is encapsulated into
ifdeffery in 8250_port / 8250_early and some if UPIO_AU blocks.
Create a separate file from them.

Also handle errors properly in the cases where RT288x/Au1xxx code is
not configured.

It seems that 0x1000 mapsize is likely overkill but I've kept it the
same as previously (the value was shrunk to that value in commit
b2b13cdfd05e ("SERIAL 8250: Fixes for Alchemy UARTs.")). Seemingly, the
driver only needs to access register at 0x28 for the divisor latch.

The Kconfig side is a bit tricky. As SERIAL_8250_RT288X is bool it can
only be =y. It is possible to have SERIAL_8250=m + SERIAL_8250_RT288X=y
which required altering when 8250/ is included or the rt288x would not
be built.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
---
 arch/mips/alchemy/common/platform.c   |  10 +-
 drivers/tty/serial/8250/8250_early.c  |  21 ----
 drivers/tty/serial/8250/8250_of.c     |   4 +-
 drivers/tty/serial/8250/8250_port.c   |  78 --------------
 drivers/tty/serial/8250/8250_rt288x.c | 142 ++++++++++++++++++++++++++
 drivers/tty/serial/8250/Makefile      |   1 +
 drivers/tty/serial/Makefile           |   2 +-
 include/linux/serial_8250.h           |   8 +-
 8 files changed, 161 insertions(+), 105 deletions(-)
 create mode 100644 drivers/tty/serial/8250/8250_rt288x.c

diff --git a/arch/mips/alchemy/common/platform.c b/arch/mips/alchemy/common/platform.c
index b8f3397c59c9..d4ab34b3b404 100644
--- a/arch/mips/alchemy/common/platform.c
+++ b/arch/mips/alchemy/common/platform.c
@@ -51,9 +51,9 @@ static void alchemy_8250_pm(struct uart_port *port, unsigned int state,
 #define PORT(_base, _irq)					\
 	{							\
 		.mapbase	= _base,			\
+		.mapsize	= 0x1000,			\
 		.irq		= _irq,				\
 		.regshift	= 2,				\
-		.iotype		= UPIO_AU,			\
 		.flags		= UPF_SKIP_TEST | UPF_IOREMAP | \
 				  UPF_FIXED_TYPE,		\
 		.type		= PORT_16550A,			\
@@ -124,8 +124,14 @@ static void __init alchemy_setup_uarts(int ctype)
 	au1xx0_uart_device.dev.platform_data = ports;
 
 	/* Fill up uartclk. */
-	for (s = 0; s < c; s++)
+	for (s = 0; s < c; s++) {
 		ports[s].uartclk = uartclk;
+		if (au_platform_setup(&ports[s]) < 0) {
+			kfree(ports);
+			printk(KERN_INFO "Alchemy: missing support for UARTs\n");
+			return;
+		}
+	}
 	if (platform_device_register(&au1xx0_uart_device))
 		printk(KERN_INFO "Alchemy: failed to register UARTs\n");
 }
diff --git a/drivers/tty/serial/8250/8250_early.c b/drivers/tty/serial/8250/8250_early.c
index 0ebde0ab8167..4299a8bd83d9 100644
--- a/drivers/tty/serial/8250/8250_early.c
+++ b/drivers/tty/serial/8250/8250_early.c
@@ -36,7 +36,6 @@
 
 static unsigned int serial8250_early_in(struct uart_port *port, int offset)
 {
-	int reg_offset = offset;
 	offset <<= port->regshift;
 
 	switch (port->iotype) {
@@ -50,8 +49,6 @@ static unsigned int serial8250_early_in(struct uart_port *port, int offset)
 		return ioread32be(port->membase + offset);
 	case UPIO_PORT:
 		return inb(port->iobase + offset);
-	case UPIO_AU:
-		return port->serial_in(port, reg_offset);
 	default:
 		return 0;
 	}
@@ -59,7 +56,6 @@ static unsigned int serial8250_early_in(struct uart_port *port, int offset)
 
 static void serial8250_early_out(struct uart_port *port, int offset, int value)
 {
-	int reg_offset = offset;
 	offset <<= port->regshift;
 
 	switch (port->iotype) {
@@ -78,9 +74,6 @@ static void serial8250_early_out(struct uart_port *port, int offset, int value)
 	case UPIO_PORT:
 		outb(value, port->iobase + offset);
 		break;
-	case UPIO_AU:
-		port->serial_out(port, reg_offset, value);
-		break;
 	}
 }
 
@@ -199,17 +192,3 @@ OF_EARLYCON_DECLARE(omap8250, "ti,omap3-uart", early_omap8250_setup);
 OF_EARLYCON_DECLARE(omap8250, "ti,omap4-uart", early_omap8250_setup);
 
 #endif
-
-#ifdef CONFIG_SERIAL_8250_RT288X
-
-static int __init early_au_setup(struct earlycon_device *dev, const char *opt)
-{
-	dev->port.serial_in = au_serial_in;
-	dev->port.serial_out = au_serial_out;
-	dev->port.iotype = UPIO_AU;
-	dev->con->write = early_serial8250_write;
-	return 0;
-}
-OF_EARLYCON_DECLARE(palmchip, "ralink,rt2880-uart", early_au_setup);
-
-#endif
diff --git a/drivers/tty/serial/8250/8250_of.c b/drivers/tty/serial/8250/8250_of.c
index 1b461fba15a3..c9f6bd7a7038 100644
--- a/drivers/tty/serial/8250/8250_of.c
+++ b/drivers/tty/serial/8250/8250_of.c
@@ -171,7 +171,9 @@ static int of_platform_serial_setup(struct platform_device *ofdev,
 
 	switch (type) {
 	case PORT_RT2880:
-		port->iotype = UPIO_AU;
+		ret = rt288x_setup(port);
+		if (ret)
+			goto err_unprepare;
 		break;
 	}
 
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 344bd447639b..0cef9bfd0471 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -341,66 +341,6 @@ static void default_serial_dl_write(struct uart_8250_port *up, u32 value)
 	serial_out(up, UART_DLM, value >> 8 & 0xff);
 }
 
-#ifdef CONFIG_SERIAL_8250_RT288X
-
-#define UART_REG_UNMAPPED	-1
-
-/* Au1x00/RT288x UART hardware has a weird register layout */
-static const s8 au_io_in_map[8] = {
-	[UART_RX]	= 0,
-	[UART_IER]	= 2,
-	[UART_IIR]	= 3,
-	[UART_LCR]	= 5,
-	[UART_MCR]	= 6,
-	[UART_LSR]	= 7,
-	[UART_MSR]	= 8,
-	[UART_SCR]	= UART_REG_UNMAPPED,
-};
-
-static const s8 au_io_out_map[8] = {
-	[UART_TX]	= 1,
-	[UART_IER]	= 2,
-	[UART_FCR]	= 4,
-	[UART_LCR]	= 5,
-	[UART_MCR]	= 6,
-	[UART_LSR]	= UART_REG_UNMAPPED,
-	[UART_MSR]	= UART_REG_UNMAPPED,
-	[UART_SCR]	= UART_REG_UNMAPPED,
-};
-
-unsigned int au_serial_in(struct uart_port *p, int offset)
-{
-	if (offset >= ARRAY_SIZE(au_io_in_map))
-		return UINT_MAX;
-	offset = au_io_in_map[offset];
-	if (offset == UART_REG_UNMAPPED)
-		return UINT_MAX;
-	return __raw_readl(p->membase + (offset << p->regshift));
-}
-
-void au_serial_out(struct uart_port *p, int offset, int value)
-{
-	if (offset >= ARRAY_SIZE(au_io_out_map))
-		return;
-	offset = au_io_out_map[offset];
-	if (offset == UART_REG_UNMAPPED)
-		return;
-	__raw_writel(value, p->membase + (offset << p->regshift));
-}
-
-/* Au1x00 haven't got a standard divisor latch */
-static u32 au_serial_dl_read(struct uart_8250_port *up)
-{
-	return __raw_readl(up->port.membase + 0x28);
-}
-
-static void au_serial_dl_write(struct uart_8250_port *up, u32 value)
-{
-	__raw_writel(value, up->port.membase + 0x28);
-}
-
-#endif
-
 static unsigned int hub6_serial_in(struct uart_port *p, int offset)
 {
 	offset = offset << p->regshift;
@@ -510,15 +450,6 @@ static void set_io_from_upio(struct uart_port *p)
 		p->serial_out = mem32be_serial_out;
 		break;
 
-#ifdef CONFIG_SERIAL_8250_RT288X
-	case UPIO_AU:
-		p->serial_in = au_serial_in;
-		p->serial_out = au_serial_out;
-		up->dl_read = au_serial_dl_read;
-		up->dl_write = au_serial_dl_write;
-		break;
-#endif
-
 	default:
 		p->serial_in = io_serial_in;
 		p->serial_out = io_serial_out;
@@ -2968,11 +2899,6 @@ static unsigned int serial8250_port_size(struct uart_8250_port *pt)
 {
 	if (pt->port.mapsize)
 		return pt->port.mapsize;
-	if (pt->port.iotype == UPIO_AU) {
-		if (pt->port.type == PORT_RT2880)
-			return 0x100;
-		return 0x1000;
-	}
 	if (is_omap1_8250(pt))
 		return 0x16 << pt->port.regshift;
 
@@ -3222,10 +3148,6 @@ static void serial8250_config_port(struct uart_port *port, int flags)
 	if (flags & UART_CONFIG_TYPE)
 		autoconfig(up);
 
-	/* if access method is AU, it is a 16550 with a quirk */
-	if (port->type == PORT_16550A && port->iotype == UPIO_AU)
-		up->bugs |= UART_BUG_NOMSR;
-
 	/* HW bugs may trigger IRQ while IIR == NO_INT */
 	if (port->type == PORT_TEGRA)
 		up->bugs |= UART_BUG_NOMSR;
diff --git a/drivers/tty/serial/8250/8250_rt288x.c b/drivers/tty/serial/8250/8250_rt288x.c
new file mode 100644
index 000000000000..51b1cf5476dd
--- /dev/null
+++ b/drivers/tty/serial/8250/8250_rt288x.c
@@ -0,0 +1,142 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * RT288x/Au1xxx driver
+ */
+
+#include <linux/module.h>
+#include <linux/io.h>
+#include <linux/init.h>
+#include <linux/console.h>
+#include <linux/serial.h>
+#include <linux/serial_8250.h>
+
+#include "8250.h"
+
+#define UART_REG_UNMAPPED	-1
+
+/* Au1x00/RT288x UART hardware has a weird register layout */
+static const s8 au_io_in_map[8] = {
+	[UART_RX]	= 0,
+	[UART_IER]	= 2,
+	[UART_IIR]	= 3,
+	[UART_LCR]	= 5,
+	[UART_MCR]	= 6,
+	[UART_LSR]	= 7,
+	[UART_MSR]	= 8,
+	[UART_SCR]	= UART_REG_UNMAPPED,
+};
+
+static const s8 au_io_out_map[8] = {
+	[UART_TX]	= 1,
+	[UART_IER]	= 2,
+	[UART_FCR]	= 4,
+	[UART_LCR]	= 5,
+	[UART_MCR]	= 6,
+	[UART_LSR]	= UART_REG_UNMAPPED,
+	[UART_MSR]	= UART_REG_UNMAPPED,
+	[UART_SCR]	= UART_REG_UNMAPPED,
+};
+
+static unsigned int au_serial_in(struct uart_port *p, int offset)
+{
+	if (offset >= ARRAY_SIZE(au_io_in_map))
+		return UINT_MAX;
+	offset = au_io_in_map[offset];
+	if (offset == UART_REG_UNMAPPED)
+		return UINT_MAX;
+	return __raw_readl(p->membase + (offset << p->regshift));
+}
+
+static void au_serial_out(struct uart_port *p, int offset, int value)
+{
+	if (offset >= ARRAY_SIZE(au_io_out_map))
+		return;
+	offset = au_io_out_map[offset];
+	if (offset == UART_REG_UNMAPPED)
+		return;
+	__raw_writel(value, p->membase + (offset << p->regshift));
+}
+
+/* Au1x00 haven't got a standard divisor latch */
+static u32 au_serial_dl_read(struct uart_8250_port *up)
+{
+	return __raw_readl(up->port.membase + 0x28);
+}
+
+static void au_serial_dl_write(struct uart_8250_port *up, u32 value)
+{
+	__raw_writel(value, up->port.membase + 0x28);
+}
+
+int au_platform_setup(struct plat_serial8250_port *p)
+{
+	p->iotype = UPIO_AU;
+
+	p->serial_in = au_serial_in;
+	p->serial_out = au_serial_out;
+	p->dl_read = au_serial_dl_read;
+	p->dl_write = au_serial_dl_write;
+
+	p->mapsize = 0x1000;
+
+	p->bugs |= UART_BUG_NOMSR;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(au_platform_setup);
+
+int rt288x_setup(struct uart_port *p)
+{
+	struct uart_8250_port *up = up_to_u8250p(p);
+
+	p->iotype = UPIO_AU;
+
+	p->serial_in = au_serial_in;
+	p->serial_out = au_serial_out;
+	up->dl_read = au_serial_dl_read;
+	up->dl_write = au_serial_dl_write;
+
+	p->mapsize = 0x100;
+
+	up->bugs |= UART_BUG_NOMSR;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(rt288x_setup);
+
+#ifdef CONFIG_SERIAL_8250_CONSOLE
+static void au_putc(struct uart_port *port, unsigned char c)
+{
+	unsigned int status;
+
+	au_serial_out(port, UART_TX, c);
+
+	for (;;) {
+		status = au_serial_in(port, UART_LSR);
+		if (uart_lsr_tx_empty(status))
+			break;
+		cpu_relax();
+	}
+}
+
+static void au_early_serial8250_write(struct console *console,
+				      const char *s, unsigned int count)
+{
+	struct earlycon_device *device = console->data;
+	struct uart_port *port = &device->port;
+
+	uart_console_write(port, s, count, au_putc);
+}
+
+static int __init early_au_setup(struct earlycon_device *dev, const char *opt)
+{
+	rt288x_setup(&dev->port);
+	dev->con->write = au_early_serial8250_write;
+
+	return 0;
+}
+OF_EARLYCON_DECLARE(palmchip, "ralink,rt2880-uart", early_au_setup);
+#endif
+
+MODULE_DESCRIPTION("RT288x/Au1xxx UART driver");
+MODULE_LICENSE("GPL");
diff --git a/drivers/tty/serial/8250/Makefile b/drivers/tty/serial/8250/Makefile
index 4fc2fc1f41b6..628b75be312e 100644
--- a/drivers/tty/serial/8250/Makefile
+++ b/drivers/tty/serial/8250/Makefile
@@ -35,6 +35,7 @@ obj-$(CONFIG_SERIAL_8250_DW)		+= 8250_dw.o
 obj-$(CONFIG_SERIAL_8250_EM)		+= 8250_em.o
 obj-$(CONFIG_SERIAL_8250_IOC3)		+= 8250_ioc3.o
 obj-$(CONFIG_SERIAL_8250_OMAP)		+= 8250_omap.o
+obj-$(CONFIG_SERIAL_8250_RT288X)	+= 8250_rt288x.o
 obj-$(CONFIG_SERIAL_8250_LPC18XX)	+= 8250_lpc18xx.o
 obj-$(CONFIG_SERIAL_8250_MT6577)	+= 8250_mtk.o
 obj-$(CONFIG_SERIAL_8250_UNIPHIER)	+= 8250_uniphier.o
diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
index cd9afd9e3018..531ec3a19dae 100644
--- a/drivers/tty/serial/Makefile
+++ b/drivers/tty/serial/Makefile
@@ -21,7 +21,7 @@ obj-$(CONFIG_SERIAL_SUNSAB) += sunsab.o
 obj-$(CONFIG_SERIAL_21285) += 21285.o
 
 # Now bring in any enabled 8250/16450/16550 type drivers.
-obj-$(CONFIG_SERIAL_8250) += 8250/
+obj-y += 8250/
 
 obj-$(CONFIG_SERIAL_AMBA_PL010) += amba-pl010.o
 obj-$(CONFIG_SERIAL_AMBA_PL011) += amba-pl011.o
diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h
index 42fc8f64f48e..eb44420b39ec 100644
--- a/include/linux/serial_8250.h
+++ b/include/linux/serial_8250.h
@@ -7,6 +7,7 @@
 #ifndef _LINUX_SERIAL_8250_H
 #define _LINUX_SERIAL_8250_H
 
+#include <linux/errno.h>
 #include <linux/serial_core.h>
 #include <linux/serial_reg.h>
 #include <linux/platform_device.h>
@@ -211,8 +212,11 @@ void serial8250_set_isa_configurator(void (*v)(int port, struct uart_port *up,
 					       u32 *capabilities));
 
 #ifdef CONFIG_SERIAL_8250_RT288X
-unsigned int au_serial_in(struct uart_port *p, int offset);
-void au_serial_out(struct uart_port *p, int offset, int value);
+int rt288x_setup(struct uart_port *p);
+int au_platform_setup(struct plat_serial8250_port *p);
+#else
+static inline int rt288x_setup(struct uart_port *p) { return -ENODEV; }
+static inline int au_platform_setup(struct plat_serial8250_port *p) { return -ENODEV; }
 #endif
 
 #endif
-- 
2.30.2

[PATCH v4 5/6] serial: 8250_rt288x: Name non-standard divisor latch reg

[Ilpo Järvinen]

Instead of a literal, add proper name for the non-standard divisor
latch register.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
---
 drivers/tty/serial/8250/8250_rt288x.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_rt288x.c b/drivers/tty/serial/8250/8250_rt288x.c
index 51b1cf5476dd..b091a1269bfa 100644
--- a/drivers/tty/serial/8250/8250_rt288x.c
+++ b/drivers/tty/serial/8250/8250_rt288x.c
@@ -12,6 +12,8 @@
 
 #include "8250.h"
 
+#define RT288X_DL	0x28
+
 #define UART_REG_UNMAPPED	-1
 
 /* Au1x00/RT288x UART hardware has a weird register layout */
@@ -60,12 +62,12 @@ static void au_serial_out(struct uart_port *p, int offset, int value)
 /* Au1x00 haven't got a standard divisor latch */
 static u32 au_serial_dl_read(struct uart_8250_port *up)
 {
-	return __raw_readl(up->port.membase + 0x28);
+	return __raw_readl(up->port.membase + RT288X_DL);
 }
 
 static void au_serial_dl_write(struct uart_8250_port *up, u32 value)
 {
-	__raw_writel(value, up->port.membase + 0x28);
+	__raw_writel(value, up->port.membase + RT288X_DL);
 }
 
 int au_platform_setup(struct plat_serial8250_port *p)
-- 
2.30.2

[PATCH v4 6/6] serial: 8250_rt288x: Remove unnecessary UART_REG_UNMAPPED

[Ilpo Järvinen]

As unmapped registers are at the tail of the array, the ARRAY_SIZE()
condition will catch them just fine. No need to define special
value for them.

Convert the arrays to u8 as all entiries are now positive.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
---
 drivers/tty/serial/8250/8250_rt288x.c | 16 ++++------------
 1 file changed, 4 insertions(+), 12 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_rt288x.c b/drivers/tty/serial/8250/8250_rt288x.c
index b091a1269bfa..6415ca8d3adf 100644
--- a/drivers/tty/serial/8250/8250_rt288x.c
+++ b/drivers/tty/serial/8250/8250_rt288x.c
@@ -14,10 +14,8 @@
 
 #define RT288X_DL	0x28
 
-#define UART_REG_UNMAPPED	-1
-
 /* Au1x00/RT288x UART hardware has a weird register layout */
-static const s8 au_io_in_map[8] = {
+static const u8 au_io_in_map[7] = {
 	[UART_RX]	= 0,
 	[UART_IER]	= 2,
 	[UART_IIR]	= 3,
@@ -25,18 +23,14 @@ static const s8 au_io_in_map[8] = {
 	[UART_MCR]	= 6,
 	[UART_LSR]	= 7,
 	[UART_MSR]	= 8,
-	[UART_SCR]	= UART_REG_UNMAPPED,
 };
 
-static const s8 au_io_out_map[8] = {
+static const u8 au_io_out_map[5] = {
 	[UART_TX]	= 1,
 	[UART_IER]	= 2,
 	[UART_FCR]	= 4,
 	[UART_LCR]	= 5,
 	[UART_MCR]	= 6,
-	[UART_LSR]	= UART_REG_UNMAPPED,
-	[UART_MSR]	= UART_REG_UNMAPPED,
-	[UART_SCR]	= UART_REG_UNMAPPED,
 };
 
 static unsigned int au_serial_in(struct uart_port *p, int offset)
@@ -44,8 +38,7 @@ static unsigned int au_serial_in(struct uart_port *p, int offset)
 	if (offset >= ARRAY_SIZE(au_io_in_map))
 		return UINT_MAX;
 	offset = au_io_in_map[offset];
-	if (offset == UART_REG_UNMAPPED)
-		return UINT_MAX;
+
 	return __raw_readl(p->membase + (offset << p->regshift));
 }
 
@@ -54,8 +47,7 @@ static void au_serial_out(struct uart_port *p, int offset, int value)
 	if (offset >= ARRAY_SIZE(au_io_out_map))
 		return;
 	offset = au_io_out_map[offset];
-	if (offset == UART_REG_UNMAPPED)
-		return;
+
 	__raw_writel(value, p->membase + (offset << p->regshift));
 }
 
-- 
2.30.2