[PATCH v3 00/10] drivers: PL011: add ARM SBSA Generic UART support

[PATCH v3 00/10] drivers: PL011: add ARM SBSA Generic UART support

[Andre Przywara]

This is the third revision of the SBSA UART support series.
It is based on tty-next plus Dave's latest PL011 work[2], which fixes
all problems seen on the fast models and on some hardware.
Compared to v2 building as a module has been fixed.

----

The ARM Server Base System Architecture[1] document describes a
generic UART which is a subset of the PL011 UART.
It lacks DMA support, baud rate control and modem status line
control, among other things.
The idea is to move the UART initialization and setup into the
firmware (which does this job today already) and let the kernel just
use the UART for sending and receiving characters.

This patchset integrates support for this UART subset into the
existing PL011 driver - basically by refactoring some
functions and providing a new uart_ops structure for it. It also has
a separate probe function to be not dependent on AMBA/PrimeCell.
It provides a device tree binding, but can easily be adapted to other
device configuration systems.
Beside the obvious effect of code sharing reusing most of the PL011
code has the advantage of not introducing another serial device
prefix, so it can go with ttyAMA, which seems to be pretty common.
As changing the baudrate and other communication parameters is not
specified for the SBSA UART, any userland attempt will be denied by
the kernel. The device-tree provided fixed baud rate will be
reported, so stty for instance prints the right value.

This series relies on Dave's recent PL011 fix[2], which gets rid of
the loopback trick to get the UART going. There is a repo at [3]
(branch sbsa-uart/v3), which has all patches already integrated.

Patch 1/10 contains a bug fix which applies to the PL011 part also,
it should be considered regardless of the rest of the series.
According to Russell this is still racy, but still better than the
current solution.
Patch 2-7 refactor some PL011 functions by splitting them up into
smaller pieces, so that most of the code can be reused later by the
SBSA part.
Patch 8 and 9 introduce two new properties for the vendor structure,
this is for SBSA functionality which cannot be controlled by
separate uart_ops members only.
Patch 10 then finally drops in the SBSA specific code, by providing
a new uart_ops, vendor struct and probe function for it. Also the new
device tree binding is documented.

For testing you should be able to take any hardware which has a PL011
and change the DT to use a "arm,sbsa-uart" compatible string and the
baud rate with the "current-speed" property.
Of course testing with a real SBSA Generic UART is welcomed - as well
as regression testing with any PL011 implementation.

Changelog:
v2 .. v3:
- rebased on top of tty-next and Dave's latest PL011 rework[2]
- fixed module build
- removed redundant =NULL members in sbsa_uart_ops

v1 .. v2:
- rebased on top of 4.0-rc1 and Dave's newest PL011 fix [4]
- added mandatory current-speed property and report that to userland

Cheers,
Andre

[1] ARM-DEN-0029 Server Base System Architecture, available (click-
    thru...) from http://infocenter.arm.com
[2] http://lists.infradead.org/pipermail/linux-arm-kernel/2015-April/334975.html
[3] http://www.linux-arm.org/git?p=linux-ap.git
    git://linux-arm.org/linux-ap.git
[4] http://lists.infradead.org/pipermail/linux-arm-kernel/2015-March/327631.html

===========================================
Andre Przywara (10):
  drivers: PL011: avoid potential unregister_driver call
  drivers: PL011: refactor pl011_startup()
  drivers: PL011: refactor pl011_shutdown()
  drivers: PL011: refactor pl011_set_termios()
  drivers: PL011: refactor pl011_probe()
  drivers: PL011: replace UART_MIS reading with _RIS & _IMSC
  drivers: PL011: move cts_event workaround into separate function
  drivers: PL011: allow avoiding UART enabling/disabling
  drivers: PL011: allow to supply fixed option string
  drivers: PL011: add support for the ARM SBSA generic UART

 .../devicetree/bindings/serial/arm_sbsa_uart.txt   |   10 +
 drivers/tty/serial/amba-pl011.c                    |  529 ++++++++++++++------
 2 files changed, 398 insertions(+), 141 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/serial/arm_sbsa_uart.txt

-- 
1.7.9.5

[PATCH v3 00/10] drivers: PL011: add ARM SBSA Generic UART support

[Andre Przywara]

This is the third revision of the SBSA UART support series.
It is based on tty-next plus Dave's latest PL011 work[2], which fixes
all problems seen on the fast models and on some hardware.
Compared to v2 building as a module has been fixed.

----

The ARM Server Base System Architecture[1] document describes a
generic UART which is a subset of the PL011 UART.
It lacks DMA support, baud rate control and modem status line
control, among other things.
The idea is to move the UART initialization and setup into the
firmware (which does this job today already) and let the kernel just
use the UART for sending and receiving characters.

This patchset integrates support for this UART subset into the
existing PL011 driver - basically by refactoring some
functions and providing a new uart_ops structure for it. It also has
a separate probe function to be not dependent on AMBA/PrimeCell.
It provides a device tree binding, but can easily be adapted to other
device configuration systems.
Beside the obvious effect of code sharing reusing most of the PL011
code has the advantage of not introducing another serial device
prefix, so it can go with ttyAMA, which seems to be pretty common.
As changing the baudrate and other communication parameters is not
specified for the SBSA UART, any userland attempt will be denied by
the kernel. The device-tree provided fixed baud rate will be
reported, so stty for instance prints the right value.

This series relies on Dave's recent PL011 fix[2], which gets rid of
the loopback trick to get the UART going. There is a repo at [3]
(branch sbsa-uart/v3), which has all patches already integrated.

Patch 1/10 contains a bug fix which applies to the PL011 part also,
it should be considered regardless of the rest of the series.
According to Russell this is still racy, but still better than the
current solution.
Patch 2-7 refactor some PL011 functions by splitting them up into
smaller pieces, so that most of the code can be reused later by the
SBSA part.
Patch 8 and 9 introduce two new properties for the vendor structure,
this is for SBSA functionality which cannot be controlled by
separate uart_ops members only.
Patch 10 then finally drops in the SBSA specific code, by providing
a new uart_ops, vendor struct and probe function for it. Also the new
device tree binding is documented.

For testing you should be able to take any hardware which has a PL011
and change the DT to use a "arm,sbsa-uart" compatible string and the
baud rate with the "current-speed" property.
Of course testing with a real SBSA Generic UART is welcomed - as well
as regression testing with any PL011 implementation.

Changelog:
v2 .. v3:
- rebased on top of tty-next and Dave's latest PL011 rework[2]
- fixed module build
- removed redundant =NULL members in sbsa_uart_ops

v1 .. v2:
- rebased on top of 4.0-rc1 and Dave's newest PL011 fix [4]
- added mandatory current-speed property and report that to userland

Cheers,
Andre

[1] ARM-DEN-0029 Server Base System Architecture, available (click-
    thru...) from http://infocenter.arm.com
[2] http://lists.infradead.org/pipermail/linux-arm-kernel/2015-April/334975.html
[3] http://www.linux-arm.org/git?p=linux-ap.git
    git://linux-arm.org/linux-ap.git
[4] http://lists.infradead.org/pipermail/linux-arm-kernel/2015-March/327631.html

===========================================
Andre Przywara (10):
  drivers: PL011: avoid potential unregister_driver call
  drivers: PL011: refactor pl011_startup()
  drivers: PL011: refactor pl011_shutdown()
  drivers: PL011: refactor pl011_set_termios()
  drivers: PL011: refactor pl011_probe()
  drivers: PL011: replace UART_MIS reading with _RIS & _IMSC
  drivers: PL011: move cts_event workaround into separate function
  drivers: PL011: allow avoiding UART enabling/disabling
  drivers: PL011: allow to supply fixed option string
  drivers: PL011: add support for the ARM SBSA generic UART

 .../devicetree/bindings/serial/arm_sbsa_uart.txt   |   10 +
 drivers/tty/serial/amba-pl011.c                    |  529 ++++++++++++++------
 2 files changed, 398 insertions(+), 141 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/serial/arm_sbsa_uart.txt

-- 
1.7.9.5

[PATCH v3 01/10] drivers: PL011: avoid potential unregister_driver call

[Andre Przywara]

Although we care about not unregistering the driver if there are
still ports connected during the .remove callback, we do miss this
check in the pl011_probe function. So if the current port allocation
fails, but there are other ports already registered, we will kill
those.
So factor out the port removal into a separate function and use that
in the probe function, too.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 drivers/tty/serial/amba-pl011.c |   37 +++++++++++++++++++++----------------
 1 file changed, 21 insertions(+), 16 deletions(-)

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index f5bd842..d08951f 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -2135,6 +2135,24 @@ static int pl011_probe_dt_alias(int index, struct device *dev)
 	return ret;
 }
 
+/* unregisters the driver also if no more ports are left */
+static void pl011_unregister_port(struct uart_amba_port *uap)
+{
+	int i;
+	bool busy = false;
+
+	for (i = 0; i < ARRAY_SIZE(amba_ports); i++) {
+		if (amba_ports[i] == uap)
+			amba_ports[i] = NULL;
+		else if (amba_ports[i])
+			busy = true;
+	}
+	pl011_dma_remove(uap);
+	if (!busy)
+		uart_unregister_driver(&amba_reg);
+}
+
+
 static int pl011_probe(struct amba_device *dev, const struct amba_id *id)
 {
 	struct uart_amba_port *uap;
@@ -2200,10 +2218,8 @@ static int pl011_probe(struct amba_device *dev, const struct amba_id *id)
 	}
 
 	ret = uart_add_one_port(&amba_reg, &uap->port);
-	if (ret) {
-		amba_ports[i] = NULL;
-		uart_unregister_driver(&amba_reg);
-	}
+	if (ret)
+		pl011_unregister_port(uap);
 
 	return ret;
 }
@@ -2211,20 +2227,9 @@ static int pl011_probe(struct amba_device *dev, const struct amba_id *id)
 static int pl011_remove(struct amba_device *dev)
 {
 	struct uart_amba_port *uap = amba_get_drvdata(dev);
-	bool busy = false;
-	int i;
 
 	uart_remove_one_port(&amba_reg, &uap->port);
-
-	for (i = 0; i < ARRAY_SIZE(amba_ports); i++)
-		if (amba_ports[i] == uap)
-			amba_ports[i] = NULL;
-		else if (amba_ports[i])
-			busy = true;
-
-	pl011_dma_remove(uap);
-	if (!busy)
-		uart_unregister_driver(&amba_reg);
+	pl011_unregister_port(uap);
 	return 0;
 }
 
-- 
1.7.9.5

[PATCH v3 01/10] drivers: PL011: avoid potential unregister_driver call

[Andre Przywara]

Although we care about not unregistering the driver if there are
still ports connected during the .remove callback, we do miss this
check in the pl011_probe function. So if the current port allocation
fails, but there are other ports already registered, we will kill
those.
So factor out the port removal into a separate function and use that
in the probe function, too.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 drivers/tty/serial/amba-pl011.c |   37 +++++++++++++++++++++----------------
 1 file changed, 21 insertions(+), 16 deletions(-)

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index f5bd842..d08951f 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -2135,6 +2135,24 @@ static int pl011_probe_dt_alias(int index, struct device *dev)
 	return ret;
 }
 
+/* unregisters the driver also if no more ports are left */
+static void pl011_unregister_port(struct uart_amba_port *uap)
+{
+	int i;
+	bool busy = false;
+
+	for (i = 0; i < ARRAY_SIZE(amba_ports); i++) {
+		if (amba_ports[i] == uap)
+			amba_ports[i] = NULL;
+		else if (amba_ports[i])
+			busy = true;
+	}
+	pl011_dma_remove(uap);
+	if (!busy)
+		uart_unregister_driver(&amba_reg);
+}
+
+
 static int pl011_probe(struct amba_device *dev, const struct amba_id *id)
 {
 	struct uart_amba_port *uap;
@@ -2200,10 +2218,8 @@ static int pl011_probe(struct amba_device *dev, const struct amba_id *id)
 	}
 
 	ret = uart_add_one_port(&amba_reg, &uap->port);
-	if (ret) {
-		amba_ports[i] = NULL;
-		uart_unregister_driver(&amba_reg);
-	}
+	if (ret)
+		pl011_unregister_port(uap);
 
 	return ret;
 }
@@ -2211,20 +2227,9 @@ static int pl011_probe(struct amba_device *dev, const struct amba_id *id)
 static int pl011_remove(struct amba_device *dev)
 {
 	struct uart_amba_port *uap = amba_get_drvdata(dev);
-	bool busy = false;
-	int i;
 
 	uart_remove_one_port(&amba_reg, &uap->port);
-
-	for (i = 0; i < ARRAY_SIZE(amba_ports); i++)
-		if (amba_ports[i] == uap)
-			amba_ports[i] = NULL;
-		else if (amba_ports[i])
-			busy = true;
-
-	pl011_dma_remove(uap);
-	if (!busy)
-		uart_unregister_driver(&amba_reg);
+	pl011_unregister_port(uap);
 	return 0;
 }
 
-- 
1.7.9.5

[PATCH v3 02/10] drivers: PL011: refactor pl011_startup()

[Andre Przywara]

Split the pl011_startup() function into smaller chunks to allow
easier reuse later when adding SBSA support.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 drivers/tty/serial/amba-pl011.c |   48 +++++++++++++++++++++++----------------
 1 file changed, 28 insertions(+), 20 deletions(-)

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index d08951f..d6a081e 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -1556,6 +1556,32 @@ static void pl011_write_lcr_h(struct uart_amba_port *uap, unsigned int lcr_h)
 	}
 }
 
+static int pl011_allocate_irq(struct uart_amba_port *uap)
+{
+	writew(uap->im, uap->port.membase + UART011_IMSC);
+
+	return request_irq(uap->port.irq, pl011_int, 0, "uart-pl011", uap);
+}
+
+/*
+ * Enable interrupts, only timeouts when using DMA
+ * if initial RX DMA job failed, start in interrupt mode
+ * as well.
+ */
+static void pl011_enable_interrupts(struct uart_amba_port *uap)
+{
+	spin_lock_irq(&uap->port.lock);
+
+	/* Clear out any spuriously appearing RX interrupts */
+	writew(UART011_RTIS | UART011_RXIS,
+		uap->port.membase + UART011_ICR);
+	uap->im = UART011_RTIM;
+	if (!pl011_dma_rx_running(uap))
+		uap->im |= UART011_RXIM;
+	writew(uap->im, uap->port.membase + UART011_IMSC);
+	spin_unlock_irq(&uap->port.lock);
+}
+
 static int pl011_startup(struct uart_port *port)
 {
 	struct uart_amba_port *uap =
@@ -1567,12 +1593,7 @@ static int pl011_startup(struct uart_port *port)
 	if (retval)
 		goto clk_dis;
 
-	writew(uap->im, uap->port.membase + UART011_IMSC);
-
-	/*
-	 * Allocate the IRQ
-	 */
-	retval = request_irq(uap->port.irq, pl011_int, 0, "uart-pl011", uap);
+	retval = pl011_allocate_irq(uap);
 	if (retval)
 		goto clk_dis;
 
@@ -1595,20 +1616,7 @@ static int pl011_startup(struct uart_port *port)
 	/* Startup DMA */
 	pl011_dma_startup(uap);
 
-	/*
-	 * Finally, enable interrupts, only timeouts when using DMA
-	 * if initial RX DMA job failed, start in interrupt mode
-	 * as well.
-	 */
-	spin_lock_irq(&uap->port.lock);
-	/* Clear out any spuriously appearing RX interrupts */
-	 writew(UART011_RTIS | UART011_RXIS,
-		uap->port.membase + UART011_ICR);
-	uap->im = UART011_RTIM;
-	if (!pl011_dma_rx_running(uap))
-		uap->im |= UART011_RXIM;
-	writew(uap->im, uap->port.membase + UART011_IMSC);
-	spin_unlock_irq(&uap->port.lock);
+	pl011_enable_interrupts(uap);
 
 	return 0;
 
-- 
1.7.9.5

[PATCH v3 02/10] drivers: PL011: refactor pl011_startup()

[Andre Przywara]

Split the pl011_startup() function into smaller chunks to allow
easier reuse later when adding SBSA support.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 drivers/tty/serial/amba-pl011.c |   48 +++++++++++++++++++++++----------------
 1 file changed, 28 insertions(+), 20 deletions(-)

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index d08951f..d6a081e 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -1556,6 +1556,32 @@ static void pl011_write_lcr_h(struct uart_amba_port *uap, unsigned int lcr_h)
 	}
 }
 
+static int pl011_allocate_irq(struct uart_amba_port *uap)
+{
+	writew(uap->im, uap->port.membase + UART011_IMSC);
+
+	return request_irq(uap->port.irq, pl011_int, 0, "uart-pl011", uap);
+}
+
+/*
+ * Enable interrupts, only timeouts when using DMA
+ * if initial RX DMA job failed, start in interrupt mode
+ * as well.
+ */
+static void pl011_enable_interrupts(struct uart_amba_port *uap)
+{
+	spin_lock_irq(&uap->port.lock);
+
+	/* Clear out any spuriously appearing RX interrupts */
+	writew(UART011_RTIS | UART011_RXIS,
+		uap->port.membase + UART011_ICR);
+	uap->im = UART011_RTIM;
+	if (!pl011_dma_rx_running(uap))
+		uap->im |= UART011_RXIM;
+	writew(uap->im, uap->port.membase + UART011_IMSC);
+	spin_unlock_irq(&uap->port.lock);
+}
+
 static int pl011_startup(struct uart_port *port)
 {
 	struct uart_amba_port *uap =
@@ -1567,12 +1593,7 @@ static int pl011_startup(struct uart_port *port)
 	if (retval)
 		goto clk_dis;
 
-	writew(uap->im, uap->port.membase + UART011_IMSC);
-
-	/*
-	 * Allocate the IRQ
-	 */
-	retval = request_irq(uap->port.irq, pl011_int, 0, "uart-pl011", uap);
+	retval = pl011_allocate_irq(uap);
 	if (retval)
 		goto clk_dis;
 
@@ -1595,20 +1616,7 @@ static int pl011_startup(struct uart_port *port)
 	/* Startup DMA */
 	pl011_dma_startup(uap);
 
-	/*
-	 * Finally, enable interrupts, only timeouts when using DMA
-	 * if initial RX DMA job failed, start in interrupt mode
-	 * as well.
-	 */
-	spin_lock_irq(&uap->port.lock);
-	/* Clear out any spuriously appearing RX interrupts */
-	 writew(UART011_RTIS | UART011_RXIS,
-		uap->port.membase + UART011_ICR);
-	uap->im = UART011_RTIM;
-	if (!pl011_dma_rx_running(uap))
-		uap->im |= UART011_RXIM;
-	writew(uap->im, uap->port.membase + UART011_IMSC);
-	spin_unlock_irq(&uap->port.lock);
+	pl011_enable_interrupts(uap);
 
 	return 0;
 
-- 
1.7.9.5

[PATCH v3 03/10] drivers: PL011: refactor pl011_shutdown()

[Andre Przywara]

Split the pl011_shutdown() function into smaller chunks to allow
easier reuse later when adding SBSA support.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 drivers/tty/serial/amba-pl011.c |   58 ++++++++++++++++++++++-----------------
 1 file changed, 33 insertions(+), 25 deletions(-)

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index d6a081e..9eb6d13 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -1635,34 +1635,15 @@ static void pl011_shutdown_channel(struct uart_amba_port *uap,
       writew(val, uap->port.membase + lcrh);
 }
 
-static void pl011_shutdown(struct uart_port *port)
+/*
+ * disable the port. It should not disable RTS and DTR.
+ * Also RTS and DTR state should be preserved to restore
+ * it during startup().
+ */
+static void pl011_disable_uart(struct uart_amba_port *uap)
 {
-	struct uart_amba_port *uap =
-	    container_of(port, struct uart_amba_port, port);
 	unsigned int cr;
 
-	/*
-	 * disable all interrupts
-	 */
-	spin_lock_irq(&uap->port.lock);
-	uap->im = 0;
-	writew(uap->im, uap->port.membase + UART011_IMSC);
-	writew(0xffff, uap->port.membase + UART011_ICR);
-	spin_unlock_irq(&uap->port.lock);
-
-	pl011_dma_shutdown(uap);
-
-	/*
-	 * Free the interrupt
-	 */
-	free_irq(uap->port.irq, uap);
-
-	/*
-	 * disable the port
-	 * disable the port. It should not disable RTS and DTR.
-	 * Also RTS and DTR state should be preserved to restore
-	 * it during startup().
-	 */
 	uap->autorts = false;
 	spin_lock_irq(&uap->port.lock);
 	cr = readw(uap->port.membase + UART011_CR);
@@ -1678,6 +1659,33 @@ static void pl011_shutdown(struct uart_port *port)
 	pl011_shutdown_channel(uap, uap->lcrh_rx);
 	if (uap->lcrh_rx != uap->lcrh_tx)
 		pl011_shutdown_channel(uap, uap->lcrh_tx);
+}
+
+static void pl011_disable_interrupts(struct uart_amba_port *uap)
+{
+	spin_lock_irq(&uap->port.lock);
+	/*
+	 * mask all interrupts and clear all pending ones
+	 */
+	uap->im = 0;
+	writew(uap->im, uap->port.membase + UART011_IMSC);
+	writew(0xffff & ~UART011_TXIS, uap->port.membase + UART011_ICR);
+
+	spin_unlock_irq(&uap->port.lock);
+}
+
+static void pl011_shutdown(struct uart_port *port)
+{
+	struct uart_amba_port *uap =
+		container_of(port, struct uart_amba_port, port);
+
+	pl011_disable_interrupts(uap);
+
+	pl011_dma_shutdown(uap);
+
+	free_irq(uap->port.irq, uap);
+
+	pl011_disable_uart(uap);
 
 	/*
 	 * Shut down the clock producer
-- 
1.7.9.5

[PATCH v3 03/10] drivers: PL011: refactor pl011_shutdown()

[Andre Przywara]

Split the pl011_shutdown() function into smaller chunks to allow
easier reuse later when adding SBSA support.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 drivers/tty/serial/amba-pl011.c |   58 ++++++++++++++++++++++-----------------
 1 file changed, 33 insertions(+), 25 deletions(-)

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index d6a081e..9eb6d13 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -1635,34 +1635,15 @@ static void pl011_shutdown_channel(struct uart_amba_port *uap,
       writew(val, uap->port.membase + lcrh);
 }
 
-static void pl011_shutdown(struct uart_port *port)
+/*
+ * disable the port. It should not disable RTS and DTR.
+ * Also RTS and DTR state should be preserved to restore
+ * it during startup().
+ */
+static void pl011_disable_uart(struct uart_amba_port *uap)
 {
-	struct uart_amba_port *uap =
-	    container_of(port, struct uart_amba_port, port);
 	unsigned int cr;
 
-	/*
-	 * disable all interrupts
-	 */
-	spin_lock_irq(&uap->port.lock);
-	uap->im = 0;
-	writew(uap->im, uap->port.membase + UART011_IMSC);
-	writew(0xffff, uap->port.membase + UART011_ICR);
-	spin_unlock_irq(&uap->port.lock);
-
-	pl011_dma_shutdown(uap);
-
-	/*
-	 * Free the interrupt
-	 */
-	free_irq(uap->port.irq, uap);
-
-	/*
-	 * disable the port
-	 * disable the port. It should not disable RTS and DTR.
-	 * Also RTS and DTR state should be preserved to restore
-	 * it during startup().
-	 */
 	uap->autorts = false;
 	spin_lock_irq(&uap->port.lock);
 	cr = readw(uap->port.membase + UART011_CR);
@@ -1678,6 +1659,33 @@ static void pl011_shutdown(struct uart_port *port)
 	pl011_shutdown_channel(uap, uap->lcrh_rx);
 	if (uap->lcrh_rx != uap->lcrh_tx)
 		pl011_shutdown_channel(uap, uap->lcrh_tx);
+}
+
+static void pl011_disable_interrupts(struct uart_amba_port *uap)
+{
+	spin_lock_irq(&uap->port.lock);
+	/*
+	 * mask all interrupts and clear all pending ones
+	 */
+	uap->im = 0;
+	writew(uap->im, uap->port.membase + UART011_IMSC);
+	writew(0xffff & ~UART011_TXIS, uap->port.membase + UART011_ICR);
+
+	spin_unlock_irq(&uap->port.lock);
+}
+
+static void pl011_shutdown(struct uart_port *port)
+{
+	struct uart_amba_port *uap =
+		container_of(port, struct uart_amba_port, port);
+
+	pl011_disable_interrupts(uap);
+
+	pl011_dma_shutdown(uap);
+
+	free_irq(uap->port.irq, uap);
+
+	pl011_disable_uart(uap);
 
 	/*
 	 * Shut down the clock producer
-- 
1.7.9.5

[PATCH v3 04/10] drivers: PL011: refactor pl011_set_termios()

[Andre Przywara]

Split the pl011_set_termios() function into smaller chunks to allow
easier reuse later when adding SBSA support.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 drivers/tty/serial/amba-pl011.c |   60 +++++++++++++++++++++------------------
 1 file changed, 33 insertions(+), 27 deletions(-)

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 9eb6d13..e1ac2cb 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -1707,6 +1707,38 @@ static void pl011_shutdown(struct uart_port *port)
 }
 
 static void
+pl011_setup_status_masks(struct uart_port *port, struct ktermios *termios)
+{
+	port->read_status_mask = UART011_DR_OE | 255;
+	if (termios->c_iflag & INPCK)
+		port->read_status_mask |= UART011_DR_FE | UART011_DR_PE;
+	if (termios->c_iflag & (IGNBRK | BRKINT | PARMRK))
+		port->read_status_mask |= UART011_DR_BE;
+
+	/*
+	 * Characters to ignore
+	 */
+	port->ignore_status_mask = 0;
+	if (termios->c_iflag & IGNPAR)
+		port->ignore_status_mask |= UART011_DR_FE | UART011_DR_PE;
+	if (termios->c_iflag & IGNBRK) {
+		port->ignore_status_mask |= UART011_DR_BE;
+		/*
+		 * If we're ignoring parity and break indicators,
+		 * ignore overruns too (for real raw support).
+		 */
+		if (termios->c_iflag & IGNPAR)
+			port->ignore_status_mask |= UART011_DR_OE;
+	}
+
+	/*
+	 * Ignore all characters if CREAD is not set.
+	 */
+	if ((termios->c_cflag & CREAD) == 0)
+		port->ignore_status_mask |= UART_DUMMY_DR_RX;
+}
+
+static void
 pl011_set_termios(struct uart_port *port, struct ktermios *termios,
 		     struct ktermios *old)
 {
@@ -1770,33 +1802,7 @@ pl011_set_termios(struct uart_port *port, struct ktermios *termios,
 	 */
 	uart_update_timeout(port, termios->c_cflag, baud);
 
-	port->read_status_mask = UART011_DR_OE | 255;
-	if (termios->c_iflag & INPCK)
-		port->read_status_mask |= UART011_DR_FE | UART011_DR_PE;
-	if (termios->c_iflag & (IGNBRK | BRKINT | PARMRK))
-		port->read_status_mask |= UART011_DR_BE;
-
-	/*
-	 * Characters to ignore
-	 */
-	port->ignore_status_mask = 0;
-	if (termios->c_iflag & IGNPAR)
-		port->ignore_status_mask |= UART011_DR_FE | UART011_DR_PE;
-	if (termios->c_iflag & IGNBRK) {
-		port->ignore_status_mask |= UART011_DR_BE;
-		/*
-		 * If we're ignoring parity and break indicators,
-		 * ignore overruns too (for real raw support).
-		 */
-		if (termios->c_iflag & IGNPAR)
-			port->ignore_status_mask |= UART011_DR_OE;
-	}
-
-	/*
-	 * Ignore all characters if CREAD is not set.
-	 */
-	if ((termios->c_cflag & CREAD) == 0)
-		port->ignore_status_mask |= UART_DUMMY_DR_RX;
+	pl011_setup_status_masks(port, termios);
 
 	if (UART_ENABLE_MS(port, termios->c_cflag))
 		pl011_enable_ms(port);
-- 
1.7.9.5

[PATCH v3 04/10] drivers: PL011: refactor pl011_set_termios()

[Andre Przywara]

Split the pl011_set_termios() function into smaller chunks to allow
easier reuse later when adding SBSA support.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 drivers/tty/serial/amba-pl011.c |   60 +++++++++++++++++++++------------------
 1 file changed, 33 insertions(+), 27 deletions(-)

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 9eb6d13..e1ac2cb 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -1707,6 +1707,38 @@ static void pl011_shutdown(struct uart_port *port)
 }
 
 static void
+pl011_setup_status_masks(struct uart_port *port, struct ktermios *termios)
+{
+	port->read_status_mask = UART011_DR_OE | 255;
+	if (termios->c_iflag & INPCK)
+		port->read_status_mask |= UART011_DR_FE | UART011_DR_PE;
+	if (termios->c_iflag & (IGNBRK | BRKINT | PARMRK))
+		port->read_status_mask |= UART011_DR_BE;
+
+	/*
+	 * Characters to ignore
+	 */
+	port->ignore_status_mask = 0;
+	if (termios->c_iflag & IGNPAR)
+		port->ignore_status_mask |= UART011_DR_FE | UART011_DR_PE;
+	if (termios->c_iflag & IGNBRK) {
+		port->ignore_status_mask |= UART011_DR_BE;
+		/*
+		 * If we're ignoring parity and break indicators,
+		 * ignore overruns too (for real raw support).
+		 */
+		if (termios->c_iflag & IGNPAR)
+			port->ignore_status_mask |= UART011_DR_OE;
+	}
+
+	/*
+	 * Ignore all characters if CREAD is not set.
+	 */
+	if ((termios->c_cflag & CREAD) == 0)
+		port->ignore_status_mask |= UART_DUMMY_DR_RX;
+}
+
+static void
 pl011_set_termios(struct uart_port *port, struct ktermios *termios,
 		     struct ktermios *old)
 {
@@ -1770,33 +1802,7 @@ pl011_set_termios(struct uart_port *port, struct ktermios *termios,
 	 */
 	uart_update_timeout(port, termios->c_cflag, baud);
 
-	port->read_status_mask = UART011_DR_OE | 255;
-	if (termios->c_iflag & INPCK)
-		port->read_status_mask |= UART011_DR_FE | UART011_DR_PE;
-	if (termios->c_iflag & (IGNBRK | BRKINT | PARMRK))
-		port->read_status_mask |= UART011_DR_BE;
-
-	/*
-	 * Characters to ignore
-	 */
-	port->ignore_status_mask = 0;
-	if (termios->c_iflag & IGNPAR)
-		port->ignore_status_mask |= UART011_DR_FE | UART011_DR_PE;
-	if (termios->c_iflag & IGNBRK) {
-		port->ignore_status_mask |= UART011_DR_BE;
-		/*
-		 * If we're ignoring parity and break indicators,
-		 * ignore overruns too (for real raw support).
-		 */
-		if (termios->c_iflag & IGNPAR)
-			port->ignore_status_mask |= UART011_DR_OE;
-	}
-
-	/*
-	 * Ignore all characters if CREAD is not set.
-	 */
-	if ((termios->c_cflag & CREAD) == 0)
-		port->ignore_status_mask |= UART_DUMMY_DR_RX;
+	pl011_setup_status_masks(port, termios);
 
 	if (UART_ENABLE_MS(port, termios->c_cflag))
 		pl011_enable_ms(port);
-- 
1.7.9.5

[PATCH v3 05/10] drivers: PL011: refactor pl011_probe()

[Andre Przywara]

Currently the pl011_probe() function is relying on some AMBA IDs
and a device tree node to initialize the driver and a port.
Both features are not necessarily required for the driver:
- we lack AMBA IDs in the ARM SBSA generic UART and
- we lack a DT node in ACPI systems.
So lets refactor the function to ease later reuse.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 drivers/tty/serial/amba-pl011.c |   89 ++++++++++++++++++++++++++-------------
 1 file changed, 60 insertions(+), 29 deletions(-)

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index e1ac2cb..65df5c7 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -2174,13 +2174,10 @@ static void pl011_unregister_port(struct uart_amba_port *uap)
 		uart_unregister_driver(&amba_reg);
 }
 
-
-static int pl011_probe(struct amba_device *dev, const struct amba_id *id)
+static int pl011_allocate_port(struct device *dev, struct uart_amba_port **_uap)
 {
 	struct uart_amba_port *uap;
-	struct vendor_data *vendor = id->data;
-	void __iomem *base;
-	int i, ret;
+	int i;
 
 	for (i = 0; i < ARRAY_SIZE(amba_ports); i++)
 		if (amba_ports[i] == NULL)
@@ -2189,51 +2186,53 @@ static int pl011_probe(struct amba_device *dev, const struct amba_id *id)
 	if (i == ARRAY_SIZE(amba_ports))
 		return -EBUSY;
 
-	uap = devm_kzalloc(&dev->dev, sizeof(struct uart_amba_port),
-			   GFP_KERNEL);
+	uap = devm_kzalloc(dev, sizeof(struct uart_amba_port), GFP_KERNEL);
 	if (uap == NULL)
 		return -ENOMEM;
 
-	i = pl011_probe_dt_alias(i, &dev->dev);
+	if (_uap)
+		*_uap = uap;
+
+	return i;
+}
 
-	base = devm_ioremap(&dev->dev, dev->res.start,
-			    resource_size(&dev->res));
+static int pl011_setup_port(struct device *dev, struct uart_amba_port *uap,
+			    struct resource *mmiobase, int index)
+{
+	void __iomem *base;
+
+	base = devm_ioremap_resource(dev, mmiobase);
 	if (!base)
 		return -ENOMEM;
 
-	uap->clk = devm_clk_get(&dev->dev, NULL);
-	if (IS_ERR(uap->clk))
-		return PTR_ERR(uap->clk);
+	index = pl011_probe_dt_alias(index, dev);
 
-	uap->vendor = vendor;
-	uap->lcrh_rx = vendor->lcrh_rx;
-	uap->lcrh_tx = vendor->lcrh_tx;
 	uap->old_cr = 0;
-	uap->fifosize = vendor->get_fifosize(dev);
-	uap->port.dev = &dev->dev;
-	uap->port.mapbase = dev->res.start;
+	uap->port.dev = dev;
+	uap->port.mapbase = mmiobase->start;
 	uap->port.membase = base;
 	uap->port.iotype = UPIO_MEM;
-	uap->port.irq = dev->irq[0];
 	uap->port.fifosize = uap->fifosize;
-	uap->port.ops = &amba_pl011_pops;
 	uap->port.flags = UPF_BOOT_AUTOCONF;
-	uap->port.line = i;
+	uap->port.line = index;
 
-	/* Ensure interrupts from this UART are masked and cleared */
-	writew(0, uap->port.membase + UART011_IMSC);
-	writew(0xffff, uap->port.membase + UART011_ICR);
+	amba_ports[index] = uap;
 
-	snprintf(uap->type, sizeof(uap->type), "PL011 rev%u", amba_rev(dev));
+	return 0;
+}
 
-	amba_ports[i] = uap;
+static int pl011_register_port(struct uart_amba_port *uap)
+{
+	int ret;
 
-	amba_set_drvdata(dev, uap);
+	/* Ensure interrupts from this UART are masked and cleared */
+	writew(0, uap->port.membase + UART011_IMSC);
+	writew(0xffff, uap->port.membase + UART011_ICR);
 
 	if (!amba_reg.state) {
 		ret = uart_register_driver(&amba_reg);
 		if (ret < 0) {
-			dev_err(&dev->dev,
+			dev_err(uap->port.dev,
 				"Failed to register AMBA-PL011 driver\n");
 			return ret;
 		}
@@ -2246,6 +2245,38 @@ static int pl011_probe(struct amba_device *dev, const struct amba_id *id)
 	return ret;
 }
 
+static int pl011_probe(struct amba_device *dev, const struct amba_id *id)
+{
+	struct uart_amba_port *uap;
+	struct vendor_data *vendor = id->data;
+	int portnr, ret;
+
+	portnr = pl011_allocate_port(&dev->dev, &uap);
+	if (portnr < 0)
+		return portnr;
+
+	uap->clk = devm_clk_get(&dev->dev, NULL);
+	if (IS_ERR(uap->clk))
+		return PTR_ERR(uap->clk);
+
+	uap->vendor = vendor;
+	uap->lcrh_rx = vendor->lcrh_rx;
+	uap->lcrh_tx = vendor->lcrh_tx;
+	uap->fifosize = vendor->get_fifosize(dev);
+	uap->port.irq = dev->irq[0];
+	uap->port.ops = &amba_pl011_pops;
+
+	snprintf(uap->type, sizeof(uap->type), "PL011 rev%u", amba_rev(dev));
+
+	ret = pl011_setup_port(&dev->dev, uap, &dev->res, portnr);
+	if (ret)
+		return ret;
+
+	amba_set_drvdata(dev, uap);
+
+	return pl011_register_port(uap);
+}
+
 static int pl011_remove(struct amba_device *dev)
 {
 	struct uart_amba_port *uap = amba_get_drvdata(dev);
-- 
1.7.9.5

[PATCH v3 05/10] drivers: PL011: refactor pl011_probe()

[Andre Przywara]

Currently the pl011_probe() function is relying on some AMBA IDs
and a device tree node to initialize the driver and a port.
Both features are not necessarily required for the driver:
- we lack AMBA IDs in the ARM SBSA generic UART and
- we lack a DT node in ACPI systems.
So lets refactor the function to ease later reuse.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 drivers/tty/serial/amba-pl011.c |   89 ++++++++++++++++++++++++++-------------
 1 file changed, 60 insertions(+), 29 deletions(-)

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index e1ac2cb..65df5c7 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -2174,13 +2174,10 @@ static void pl011_unregister_port(struct uart_amba_port *uap)
 		uart_unregister_driver(&amba_reg);
 }
 
-
-static int pl011_probe(struct amba_device *dev, const struct amba_id *id)
+static int pl011_allocate_port(struct device *dev, struct uart_amba_port **_uap)
 {
 	struct uart_amba_port *uap;
-	struct vendor_data *vendor = id->data;
-	void __iomem *base;
-	int i, ret;
+	int i;
 
 	for (i = 0; i < ARRAY_SIZE(amba_ports); i++)
 		if (amba_ports[i] == NULL)
@@ -2189,51 +2186,53 @@ static int pl011_probe(struct amba_device *dev, const struct amba_id *id)
 	if (i == ARRAY_SIZE(amba_ports))
 		return -EBUSY;
 
-	uap = devm_kzalloc(&dev->dev, sizeof(struct uart_amba_port),
-			   GFP_KERNEL);
+	uap = devm_kzalloc(dev, sizeof(struct uart_amba_port), GFP_KERNEL);
 	if (uap == NULL)
 		return -ENOMEM;
 
-	i = pl011_probe_dt_alias(i, &dev->dev);
+	if (_uap)
+		*_uap = uap;
+
+	return i;
+}
 
-	base = devm_ioremap(&dev->dev, dev->res.start,
-			    resource_size(&dev->res));
+static int pl011_setup_port(struct device *dev, struct uart_amba_port *uap,
+			    struct resource *mmiobase, int index)
+{
+	void __iomem *base;
+
+	base = devm_ioremap_resource(dev, mmiobase);
 	if (!base)
 		return -ENOMEM;
 
-	uap->clk = devm_clk_get(&dev->dev, NULL);
-	if (IS_ERR(uap->clk))
-		return PTR_ERR(uap->clk);
+	index = pl011_probe_dt_alias(index, dev);
 
-	uap->vendor = vendor;
-	uap->lcrh_rx = vendor->lcrh_rx;
-	uap->lcrh_tx = vendor->lcrh_tx;
 	uap->old_cr = 0;
-	uap->fifosize = vendor->get_fifosize(dev);
-	uap->port.dev = &dev->dev;
-	uap->port.mapbase = dev->res.start;
+	uap->port.dev = dev;
+	uap->port.mapbase = mmiobase->start;
 	uap->port.membase = base;
 	uap->port.iotype = UPIO_MEM;
-	uap->port.irq = dev->irq[0];
 	uap->port.fifosize = uap->fifosize;
-	uap->port.ops = &amba_pl011_pops;
 	uap->port.flags = UPF_BOOT_AUTOCONF;
-	uap->port.line = i;
+	uap->port.line = index;
 
-	/* Ensure interrupts from this UART are masked and cleared */
-	writew(0, uap->port.membase + UART011_IMSC);
-	writew(0xffff, uap->port.membase + UART011_ICR);
+	amba_ports[index] = uap;
 
-	snprintf(uap->type, sizeof(uap->type), "PL011 rev%u", amba_rev(dev));
+	return 0;
+}
 
-	amba_ports[i] = uap;
+static int pl011_register_port(struct uart_amba_port *uap)
+{
+	int ret;
 
-	amba_set_drvdata(dev, uap);
+	/* Ensure interrupts from this UART are masked and cleared */
+	writew(0, uap->port.membase + UART011_IMSC);
+	writew(0xffff, uap->port.membase + UART011_ICR);
 
 	if (!amba_reg.state) {
 		ret = uart_register_driver(&amba_reg);
 		if (ret < 0) {
-			dev_err(&dev->dev,
+			dev_err(uap->port.dev,
 				"Failed to register AMBA-PL011 driver\n");
 			return ret;
 		}
@@ -2246,6 +2245,38 @@ static int pl011_probe(struct amba_device *dev, const struct amba_id *id)
 	return ret;
 }
 
+static int pl011_probe(struct amba_device *dev, const struct amba_id *id)
+{
+	struct uart_amba_port *uap;
+	struct vendor_data *vendor = id->data;
+	int portnr, ret;
+
+	portnr = pl011_allocate_port(&dev->dev, &uap);
+	if (portnr < 0)
+		return portnr;
+
+	uap->clk = devm_clk_get(&dev->dev, NULL);
+	if (IS_ERR(uap->clk))
+		return PTR_ERR(uap->clk);
+
+	uap->vendor = vendor;
+	uap->lcrh_rx = vendor->lcrh_rx;
+	uap->lcrh_tx = vendor->lcrh_tx;
+	uap->fifosize = vendor->get_fifosize(dev);
+	uap->port.irq = dev->irq[0];
+	uap->port.ops = &amba_pl011_pops;
+
+	snprintf(uap->type, sizeof(uap->type), "PL011 rev%u", amba_rev(dev));
+
+	ret = pl011_setup_port(&dev->dev, uap, &dev->res, portnr);
+	if (ret)
+		return ret;
+
+	amba_set_drvdata(dev, uap);
+
+	return pl011_register_port(uap);
+}
+
 static int pl011_remove(struct amba_device *dev)
 {
 	struct uart_amba_port *uap = amba_get_drvdata(dev);
-- 
1.7.9.5

[PATCH v3 06/10] drivers: PL011: replace UART_MIS reading with _RIS & _IMSC

[Andre Przywara]

The PL011 register UART_MIS is actually a bitwise AND of the
UART_RIS and the UART_MISC register.
Since the SBSA UART does not include the _MIS register, use the
two separate registers to get the same behaviour. Since we are
inside the spinlock and we read the _IMSC register only once, there
should be no race issue.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 drivers/tty/serial/amba-pl011.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 65df5c7..3829879 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -1322,11 +1322,13 @@ static irqreturn_t pl011_int(int irq, void *dev_id)
 	struct uart_amba_port *uap = dev_id;
 	unsigned long flags;
 	unsigned int status, pass_counter = AMBA_ISR_PASS_LIMIT;
+	u16 imsc;
 	int handled = 0;
 	unsigned int dummy_read;
 
 	spin_lock_irqsave(&uap->port.lock, flags);
-	status = readw(uap->port.membase + UART011_MIS);
+	imsc = readw(uap->port.membase + UART011_IMSC);
+	status = readw(uap->port.membase + UART011_RIS) & imsc;
 	if (status) {
 		do {
 			if (uap->vendor->cts_event_workaround) {
@@ -1361,7 +1363,7 @@ static irqreturn_t pl011_int(int irq, void *dev_id)
 			if (pass_counter-- == 0)
 				break;
 
-			status = readw(uap->port.membase + UART011_MIS);
+			status = readw(uap->port.membase + UART011_RIS) & imsc;
 		} while (status != 0);
 		handled = 1;
 	}
-- 
1.7.9.5

[PATCH v3 06/10] drivers: PL011: replace UART_MIS reading with _RIS & _IMSC

[Andre Przywara]

The PL011 register UART_MIS is actually a bitwise AND of the
UART_RIS and the UART_MISC register.
Since the SBSA UART does not include the _MIS register, use the
two separate registers to get the same behaviour. Since we are
inside the spinlock and we read the _IMSC register only once, there
should be no race issue.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 drivers/tty/serial/amba-pl011.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 65df5c7..3829879 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -1322,11 +1322,13 @@ static irqreturn_t pl011_int(int irq, void *dev_id)
 	struct uart_amba_port *uap = dev_id;
 	unsigned long flags;
 	unsigned int status, pass_counter = AMBA_ISR_PASS_LIMIT;
+	u16 imsc;
 	int handled = 0;
 	unsigned int dummy_read;
 
 	spin_lock_irqsave(&uap->port.lock, flags);
-	status = readw(uap->port.membase + UART011_MIS);
+	imsc = readw(uap->port.membase + UART011_IMSC);
+	status = readw(uap->port.membase + UART011_RIS) & imsc;
 	if (status) {
 		do {
 			if (uap->vendor->cts_event_workaround) {
@@ -1361,7 +1363,7 @@ static irqreturn_t pl011_int(int irq, void *dev_id)
 			if (pass_counter-- == 0)
 				break;
 
-			status = readw(uap->port.membase + UART011_MIS);
+			status = readw(uap->port.membase + UART011_RIS) & imsc;
 		} while (status != 0);
 		handled = 1;
 	}
-- 
1.7.9.5

[PATCH v3 07/10] drivers: PL011: move cts_event workaround into separate function

[Andre Przywara]

To avoid lines with more than 80 characters and to make the
pl011_int() function more readable, move the workaround out into a
separate function.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 drivers/tty/serial/amba-pl011.c |   33 ++++++++++++++++++++-------------
 1 file changed, 20 insertions(+), 13 deletions(-)

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 3829879..34dfccd 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -1317,6 +1317,25 @@ static void pl011_modem_status(struct uart_amba_port *uap)
 	wake_up_interruptible(&uap->port.state->port.delta_msr_wait);
 }
 
+static void check_apply_cts_event_workaround(struct uart_amba_port *uap)
+{
+	unsigned int dummy_read;
+
+	if (!uap->vendor->cts_event_workaround)
+		return;
+
+	/* workaround to make sure that all bits are unlocked.. */
+	writew(0x00, uap->port.membase + UART011_ICR);
+
+	/*
+	 * WA: introduce 26ns(1 uart clk) delay before W1C;
+	 * single apb access will incur 2 pclk(133.12Mhz) delay,
+	 * so add 2 dummy reads
+	 */
+	dummy_read = readw(uap->port.membase + UART011_ICR);
+	dummy_read = readw(uap->port.membase + UART011_ICR);
+}
+
 static irqreturn_t pl011_int(int irq, void *dev_id)
 {
 	struct uart_amba_port *uap = dev_id;
@@ -1324,25 +1343,13 @@ static irqreturn_t pl011_int(int irq, void *dev_id)
 	unsigned int status, pass_counter = AMBA_ISR_PASS_LIMIT;
 	u16 imsc;
 	int handled = 0;
-	unsigned int dummy_read;
 
 	spin_lock_irqsave(&uap->port.lock, flags);
 	imsc = readw(uap->port.membase + UART011_IMSC);
 	status = readw(uap->port.membase + UART011_RIS) & imsc;
 	if (status) {
 		do {
-			if (uap->vendor->cts_event_workaround) {
-				/* workaround to make sure that all bits are unlocked.. */
-				writew(0x00, uap->port.membase + UART011_ICR);
-
-				/*
-				 * WA: introduce 26ns(1 uart clk) delay before W1C;
-				 * single apb access will incur 2 pclk(133.12Mhz) delay,
-				 * so add 2 dummy reads
-				 */
-				dummy_read = readw(uap->port.membase + UART011_ICR);
-				dummy_read = readw(uap->port.membase + UART011_ICR);
-			}
+			check_apply_cts_event_workaround(uap);
 
 			writew(status & ~(UART011_TXIS|UART011_RTIS|
 					  UART011_RXIS),
-- 
1.7.9.5

[PATCH v3 07/10] drivers: PL011: move cts_event workaround into separate function

[Andre Przywara]

To avoid lines with more than 80 characters and to make the
pl011_int() function more readable, move the workaround out into a
separate function.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 drivers/tty/serial/amba-pl011.c |   33 ++++++++++++++++++++-------------
 1 file changed, 20 insertions(+), 13 deletions(-)

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 3829879..34dfccd 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -1317,6 +1317,25 @@ static void pl011_modem_status(struct uart_amba_port *uap)
 	wake_up_interruptible(&uap->port.state->port.delta_msr_wait);
 }
 
+static void check_apply_cts_event_workaround(struct uart_amba_port *uap)
+{
+	unsigned int dummy_read;
+
+	if (!uap->vendor->cts_event_workaround)
+		return;
+
+	/* workaround to make sure that all bits are unlocked.. */
+	writew(0x00, uap->port.membase + UART011_ICR);
+
+	/*
+	 * WA: introduce 26ns(1 uart clk) delay before W1C;
+	 * single apb access will incur 2 pclk(133.12Mhz) delay,
+	 * so add 2 dummy reads
+	 */
+	dummy_read = readw(uap->port.membase + UART011_ICR);
+	dummy_read = readw(uap->port.membase + UART011_ICR);
+}
+
 static irqreturn_t pl011_int(int irq, void *dev_id)
 {
 	struct uart_amba_port *uap = dev_id;
@@ -1324,25 +1343,13 @@ static irqreturn_t pl011_int(int irq, void *dev_id)
 	unsigned int status, pass_counter = AMBA_ISR_PASS_LIMIT;
 	u16 imsc;
 	int handled = 0;
-	unsigned int dummy_read;
 
 	spin_lock_irqsave(&uap->port.lock, flags);
 	imsc = readw(uap->port.membase + UART011_IMSC);
 	status = readw(uap->port.membase + UART011_RIS) & imsc;
 	if (status) {
 		do {
-			if (uap->vendor->cts_event_workaround) {
-				/* workaround to make sure that all bits are unlocked.. */
-				writew(0x00, uap->port.membase + UART011_ICR);
-
-				/*
-				 * WA: introduce 26ns(1 uart clk) delay before W1C;
-				 * single apb access will incur 2 pclk(133.12Mhz) delay,
-				 * so add 2 dummy reads
-				 */
-				dummy_read = readw(uap->port.membase + UART011_ICR);
-				dummy_read = readw(uap->port.membase + UART011_ICR);
-			}
+			check_apply_cts_event_workaround(uap);
 
 			writew(status & ~(UART011_TXIS|UART011_RTIS|
 					  UART011_RXIS),
-- 
1.7.9.5

[PATCH v3 08/10] drivers: PL011: allow avoiding UART enabling/disabling

[Andre Przywara]

The SBSA UART should not be enabled or disabled (it is always on),
and consequently the spec lacks the UART_CR register.
Add a vendor specific property to skip disabling or enabling of the
UART. This will be used later by the SBSA UART support.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 drivers/tty/serial/amba-pl011.c |   18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 34dfccd..98cb889 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -78,6 +78,7 @@ struct vendor_data {
 	bool			oversampling;
 	bool			dma_threshold;
 	bool			cts_event_workaround;
+	bool			always_enabled;
 
 	unsigned int (*get_fifosize)(struct amba_device *dev);
 };
@@ -94,6 +95,7 @@ static struct vendor_data vendor_arm = {
 	.oversampling		= false,
 	.dma_threshold		= false,
 	.cts_event_workaround	= false,
+	.always_enabled		= false,
 	.get_fifosize		= get_fifosize_arm,
 };
 
@@ -109,6 +111,7 @@ static struct vendor_data vendor_st = {
 	.oversampling		= true,
 	.dma_threshold		= true,
 	.cts_event_workaround	= true,
+	.always_enabled		= false,
 	.get_fifosize		= get_fifosize_st,
 };
 
@@ -1959,7 +1962,7 @@ static void
 pl011_console_write(struct console *co, const char *s, unsigned int count)
 {
 	struct uart_amba_port *uap = amba_ports[co->index];
-	unsigned int status, old_cr, new_cr;
+	unsigned int status, old_cr = 0, new_cr;
 	unsigned long flags;
 	int locked = 1;
 
@@ -1976,10 +1979,12 @@ pl011_console_write(struct console *co, const char *s, unsigned int count)
 	/*
 	 *	First save the CR then disable the interrupts
 	 */
-	old_cr = readw(uap->port.membase + UART011_CR);
-	new_cr = old_cr & ~UART011_CR_CTSEN;
-	new_cr |= UART01x_CR_UARTEN | UART011_CR_TXE;
-	writew(new_cr, uap->port.membase + UART011_CR);
+	if (!uap->vendor->always_enabled) {
+		old_cr = readw(uap->port.membase + UART011_CR);
+		new_cr = old_cr & ~UART011_CR_CTSEN;
+		new_cr |= UART01x_CR_UARTEN | UART011_CR_TXE;
+		writew(new_cr, uap->port.membase + UART011_CR);
+	}
 
 	uart_console_write(&uap->port, s, count, pl011_console_putchar);
 
@@ -1990,7 +1995,8 @@ pl011_console_write(struct console *co, const char *s, unsigned int count)
 	do {
 		status = readw(uap->port.membase + UART01x_FR);
 	} while (status & UART01x_FR_BUSY);
-	writew(old_cr, uap->port.membase + UART011_CR);
+	if (!uap->vendor->always_enabled)
+		writew(old_cr, uap->port.membase + UART011_CR);
 
 	if (locked)
 		spin_unlock(&uap->port.lock);
-- 
1.7.9.5

[PATCH v3 08/10] drivers: PL011: allow avoiding UART enabling/disabling

[Andre Przywara]

The SBSA UART should not be enabled or disabled (it is always on),
and consequently the spec lacks the UART_CR register.
Add a vendor specific property to skip disabling or enabling of the
UART. This will be used later by the SBSA UART support.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 drivers/tty/serial/amba-pl011.c |   18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 34dfccd..98cb889 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -78,6 +78,7 @@ struct vendor_data {
 	bool			oversampling;
 	bool			dma_threshold;
 	bool			cts_event_workaround;
+	bool			always_enabled;
 
 	unsigned int (*get_fifosize)(struct amba_device *dev);
 };
@@ -94,6 +95,7 @@ static struct vendor_data vendor_arm = {
 	.oversampling		= false,
 	.dma_threshold		= false,
 	.cts_event_workaround	= false,
+	.always_enabled		= false,
 	.get_fifosize		= get_fifosize_arm,
 };
 
@@ -109,6 +111,7 @@ static struct vendor_data vendor_st = {
 	.oversampling		= true,
 	.dma_threshold		= true,
 	.cts_event_workaround	= true,
+	.always_enabled		= false,
 	.get_fifosize		= get_fifosize_st,
 };
 
@@ -1959,7 +1962,7 @@ static void
 pl011_console_write(struct console *co, const char *s, unsigned int count)
 {
 	struct uart_amba_port *uap = amba_ports[co->index];
-	unsigned int status, old_cr, new_cr;
+	unsigned int status, old_cr = 0, new_cr;
 	unsigned long flags;
 	int locked = 1;
 
@@ -1976,10 +1979,12 @@ pl011_console_write(struct console *co, const char *s, unsigned int count)
 	/*
 	 *	First save the CR then disable the interrupts
 	 */
-	old_cr = readw(uap->port.membase + UART011_CR);
-	new_cr = old_cr & ~UART011_CR_CTSEN;
-	new_cr |= UART01x_CR_UARTEN | UART011_CR_TXE;
-	writew(new_cr, uap->port.membase + UART011_CR);
+	if (!uap->vendor->always_enabled) {
+		old_cr = readw(uap->port.membase + UART011_CR);
+		new_cr = old_cr & ~UART011_CR_CTSEN;
+		new_cr |= UART01x_CR_UARTEN | UART011_CR_TXE;
+		writew(new_cr, uap->port.membase + UART011_CR);
+	}
 
 	uart_console_write(&uap->port, s, count, pl011_console_putchar);
 
@@ -1990,7 +1995,8 @@ pl011_console_write(struct console *co, const char *s, unsigned int count)
 	do {
 		status = readw(uap->port.membase + UART01x_FR);
 	} while (status & UART01x_FR_BUSY);
-	writew(old_cr, uap->port.membase + UART011_CR);
+	if (!uap->vendor->always_enabled)
+		writew(old_cr, uap->port.membase + UART011_CR);
 
 	if (locked)
 		spin_unlock(&uap->port.lock);
-- 
1.7.9.5

[PATCH v3 09/10] drivers: PL011: allow to supply fixed option string

[Andre Przywara]

The SBSA UART has a fixed baud rate and flow control setting, which
cannot be changed or queried by software.
Add a vendor specific property to always return fixed values when
trying to read the console options.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 drivers/tty/serial/amba-pl011.c |   17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 98cb889..fcb95bd 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -79,6 +79,7 @@ struct vendor_data {
 	bool			dma_threshold;
 	bool			cts_event_workaround;
 	bool			always_enabled;
+	bool			fixed_options;
 
 	unsigned int (*get_fifosize)(struct amba_device *dev);
 };
@@ -96,6 +97,7 @@ static struct vendor_data vendor_arm = {
 	.dma_threshold		= false,
 	.cts_event_workaround	= false,
 	.always_enabled		= false,
+	.fixed_options		= false,
 	.get_fifosize		= get_fifosize_arm,
 };
 
@@ -112,6 +114,7 @@ static struct vendor_data vendor_st = {
 	.dma_threshold		= true,
 	.cts_event_workaround	= true,
 	.always_enabled		= false,
+	.fixed_options		= false,
 	.get_fifosize		= get_fifosize_st,
 };
 
@@ -160,6 +163,7 @@ struct uart_amba_port {
 	unsigned int		lcrh_rx;	/* vendor-specific */
 	unsigned int		old_cr;		/* state during shutdown */
 	bool			autorts;
+	unsigned int		fixed_baud;	/* vendor-set fixed baud rate */
 	char			type[12];
 #ifdef CONFIG_DMA_ENGINE
 	/* DMA stuff */
@@ -2077,10 +2081,15 @@ static int __init pl011_console_setup(struct console *co, char *options)
 
 	uap->port.uartclk = clk_get_rate(uap->clk);
 
-	if (options)
-		uart_parse_options(options, &baud, &parity, &bits, &flow);
-	else
-		pl011_console_get_options(uap, &baud, &parity, &bits);
+	if (uap->vendor->fixed_options) {
+		baud = uap->fixed_baud;
+	} else {
+		if (options)
+			uart_parse_options(options,
+					   &baud, &parity, &bits, &flow);
+		else
+			pl011_console_get_options(uap, &baud, &parity, &bits);
+	}
 
 	return uart_set_options(&uap->port, co, baud, parity, bits, flow);
 }
-- 
1.7.9.5

[PATCH v3 09/10] drivers: PL011: allow to supply fixed option string

[Andre Przywara]

The SBSA UART has a fixed baud rate and flow control setting, which
cannot be changed or queried by software.
Add a vendor specific property to always return fixed values when
trying to read the console options.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 drivers/tty/serial/amba-pl011.c |   17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 98cb889..fcb95bd 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -79,6 +79,7 @@ struct vendor_data {
 	bool			dma_threshold;
 	bool			cts_event_workaround;
 	bool			always_enabled;
+	bool			fixed_options;
 
 	unsigned int (*get_fifosize)(struct amba_device *dev);
 };
@@ -96,6 +97,7 @@ static struct vendor_data vendor_arm = {
 	.dma_threshold		= false,
 	.cts_event_workaround	= false,
 	.always_enabled		= false,
+	.fixed_options		= false,
 	.get_fifosize		= get_fifosize_arm,
 };
 
@@ -112,6 +114,7 @@ static struct vendor_data vendor_st = {
 	.dma_threshold		= true,
 	.cts_event_workaround	= true,
 	.always_enabled		= false,
+	.fixed_options		= false,
 	.get_fifosize		= get_fifosize_st,
 };
 
@@ -160,6 +163,7 @@ struct uart_amba_port {
 	unsigned int		lcrh_rx;	/* vendor-specific */
 	unsigned int		old_cr;		/* state during shutdown */
 	bool			autorts;
+	unsigned int		fixed_baud;	/* vendor-set fixed baud rate */
 	char			type[12];
 #ifdef CONFIG_DMA_ENGINE
 	/* DMA stuff */
@@ -2077,10 +2081,15 @@ static int __init pl011_console_setup(struct console *co, char *options)
 
 	uap->port.uartclk = clk_get_rate(uap->clk);
 
-	if (options)
-		uart_parse_options(options, &baud, &parity, &bits, &flow);
-	else
-		pl011_console_get_options(uap, &baud, &parity, &bits);
+	if (uap->vendor->fixed_options) {
+		baud = uap->fixed_baud;
+	} else {
+		if (options)
+			uart_parse_options(options,
+					   &baud, &parity, &bits, &flow);
+		else
+			pl011_console_get_options(uap, &baud, &parity, &bits);
+	}
 
 	return uart_set_options(&uap->port, co, baud, parity, bits, flow);
 }
-- 
1.7.9.5

[PATCH v3 10/10] drivers: PL011: add support for the ARM SBSA generic UART

[Andre Przywara]

The ARM Server Base System Architecture[1] document describes a
generic UART which is a subset of the PL011 UART.
It lacks DMA support, baud rate control and modem status line
control, among other things.
The idea is to move the UART initialization and setup into the
firmware (which does this job today already) and let the kernel just
use the UART for sending and receiving characters.

We use the recent refactoring to build a new struct uart_ops
variable which points to some new functions avoiding access to the
missing registers. We reuse as much existing PL011 code as possible.

In contrast to the PL011 the SBSA UART does not define any AMBA or
PrimeCell relations, so we go with a pretty generic probe function
which only uses platform device functions.
A DT binding is provided, but other systems can easily attach to it,
too (hint, hint!).

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 .../devicetree/bindings/serial/arm_sbsa_uart.txt   |   10 ++
 drivers/tty/serial/amba-pl011.c                    |  165 ++++++++++++++++++++
 2 files changed, 175 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/serial/arm_sbsa_uart.txt

diff --git a/Documentation/devicetree/bindings/serial/arm_sbsa_uart.txt b/Documentation/devicetree/bindings/serial/arm_sbsa_uart.txt
new file mode 100644
index 0000000..4163e7e
--- /dev/null
+++ b/Documentation/devicetree/bindings/serial/arm_sbsa_uart.txt
@@ -0,0 +1,10 @@
+* ARM SBSA defined generic UART
+This UART uses a subset of the PL011 registers and consequently lives
+in the PL011 driver. It's baudrate and other communication parameters
+cannot be adjusted at runtime, so it lacks a clock specifier here.
+
+Required properties:
+- compatible: must be "arm,sbsa-uart"
+- reg: exactly one register range
+- interrupts: exactly one interrupt specifier
+- current-speed: the (fixed) baud rate set by the firmware
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index fcb95bd..27e2051 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -101,6 +101,14 @@ static struct vendor_data vendor_arm = {
 	.get_fifosize		= get_fifosize_arm,
 };
 
+static struct vendor_data vendor_sbsa = {
+	.oversampling		= false,
+	.dma_threshold		= false,
+	.cts_event_workaround	= false,
+	.always_enabled		= true,
+	.fixed_options		= true,
+};
+
 static unsigned int get_fifosize_st(struct amba_device *dev)
 {
 	return 64;
@@ -1641,6 +1649,30 @@ static int pl011_startup(struct uart_port *port)
 	return retval;
 }
 
+static int sbsa_uart_startup(struct uart_port *port)
+{
+	struct uart_amba_port *uap =
+		container_of(port, struct uart_amba_port, port);
+	int retval;
+
+	retval = pl011_hwinit(port);
+	if (retval)
+		return retval;
+
+	retval = pl011_allocate_irq(uap);
+	if (retval)
+		return retval;
+
+	/*
+	 * The SBSA UART does not support any modem status lines.
+	 */
+	uap->old_status = 0;
+
+	pl011_enable_interrupts(uap);
+
+	return 0;
+}
+
 static void pl011_shutdown_channel(struct uart_amba_port *uap,
 					unsigned int lcrh)
 {
@@ -1722,6 +1754,19 @@ static void pl011_shutdown(struct uart_port *port)
 		uap->port.ops->flush_buffer(port);
 }
 
+static void sbsa_uart_shutdown(struct uart_port *port)
+{
+	struct uart_amba_port *uap =
+		container_of(port, struct uart_amba_port, port);
+
+	pl011_disable_interrupts(uap);
+
+	free_irq(uap->port.irq, uap);
+
+	if (uap->port.ops->flush_buffer)
+		uap->port.ops->flush_buffer(port);
+}
+
 static void
 pl011_setup_status_masks(struct uart_port *port, struct ktermios *termios)
 {
@@ -1873,6 +1918,24 @@ pl011_set_termios(struct uart_port *port, struct ktermios *termios,
 	spin_unlock_irqrestore(&port->lock, flags);
 }
 
+static void
+sbsa_uart_set_termios(struct uart_port *port, struct ktermios *termios,
+		      struct ktermios *old)
+{
+	struct uart_amba_port *uap =
+	    container_of(port, struct uart_amba_port, port);
+	unsigned long flags;
+
+	if (old)
+		tty_termios_copy_hw(termios, old);
+	tty_termios_encode_baud_rate(termios, uap->fixed_baud, uap->fixed_baud);
+
+	spin_lock_irqsave(&port->lock, flags);
+	uart_update_timeout(port, CS8, uap->fixed_baud);
+	pl011_setup_status_masks(port, termios);
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
 static const char *pl011_type(struct uart_port *port)
 {
 	struct uart_amba_port *uap =
@@ -1948,6 +2011,37 @@ static struct uart_ops amba_pl011_pops = {
 #endif
 };
 
+static void sbsa_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+}
+
+static unsigned int sbsa_uart_get_mctrl(struct uart_port *port)
+{
+	return 0;
+}
+
+static struct uart_ops sbsa_uart_pops = {
+	.tx_empty	= pl011_tx_empty,
+	.set_mctrl	= sbsa_uart_set_mctrl,
+	.get_mctrl	= sbsa_uart_get_mctrl,
+	.stop_tx	= pl011_stop_tx,
+	.start_tx	= pl011_start_tx,
+	.stop_rx	= pl011_stop_rx,
+	.startup	= sbsa_uart_startup,
+	.shutdown	= sbsa_uart_shutdown,
+	.set_termios	= sbsa_uart_set_termios,
+	.type		= pl011_type,
+	.release_port	= pl011_release_port,
+	.request_port	= pl011_request_port,
+	.config_port	= pl011_config_port,
+	.verify_port	= pl011_verify_port,
+#ifdef CONFIG_CONSOLE_POLL
+	.poll_init     = pl011_hwinit,
+	.poll_get_char = pl011_get_poll_char,
+	.poll_put_char = pl011_put_poll_char,
+#endif
+};
+
 static struct uart_amba_port *amba_ports[UART_NR];
 
 #ifdef CONFIG_SERIAL_AMBA_PL011_CONSOLE
@@ -2334,6 +2428,74 @@ static int pl011_resume(struct device *dev)
 
 static SIMPLE_DEV_PM_OPS(pl011_dev_pm_ops, pl011_suspend, pl011_resume);
 
+static int sbsa_uart_probe(struct platform_device *pdev)
+{
+	struct uart_amba_port *uap;
+	struct resource *r;
+	int portnr, ret;
+	int baudrate;
+
+	/*
+	 * Check the mandatory baud rate parameter in the DT node early
+	 * so that we can easily exit with the error.
+	 */
+	if (pdev->dev.of_node) {
+		struct device_node *np = pdev->dev.of_node;
+
+		ret = of_property_read_u32(np, "current-speed", &baudrate);
+		if (ret)
+			return ret;
+	} else {
+		baudrate = 115200;
+	}
+
+	portnr = pl011_allocate_port(&pdev->dev, &uap);
+	if (portnr < 0)
+		return portnr;
+
+	uap->vendor	= &vendor_sbsa;
+	uap->fifosize	= 32;
+	uap->port.irq	= platform_get_irq(pdev, 0);
+	uap->port.ops	= &sbsa_uart_pops;
+	uap->fixed_baud = baudrate;
+
+	snprintf(uap->type, sizeof(uap->type), "SBSA");
+
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+
+	ret = pl011_setup_port(&pdev->dev, uap, r, portnr);
+	if (ret)
+		return ret;
+
+	platform_set_drvdata(pdev, uap);
+
+	return pl011_register_port(uap);
+}
+
+static int sbsa_uart_remove(struct platform_device *pdev)
+{
+	struct uart_amba_port *uap = platform_get_drvdata(pdev);
+
+	uart_remove_one_port(&amba_reg, &uap->port);
+	pl011_unregister_port(uap);
+	return 0;
+}
+
+static const struct of_device_id sbsa_uart_match[] = {
+	{ .compatible = "arm,sbsa-uart", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, sbsa_uart_match);
+
+static struct platform_driver arm_sbsa_uart_platform_driver = {
+	.probe		= sbsa_uart_probe,
+	.remove		= sbsa_uart_remove,
+	.driver	= {
+		.name	= "sbsa-uart",
+		.of_match_table = of_match_ptr(sbsa_uart_match),
+	},
+};
+
 static struct amba_id pl011_ids[] = {
 	{
 		.id	= 0x00041011,
@@ -2364,11 +2526,14 @@ static int __init pl011_init(void)
 {
 	printk(KERN_INFO "Serial: AMBA PL011 UART driver\n");
 
+	if (platform_driver_register(&arm_sbsa_uart_platform_driver))
+		pr_warn("could not register SBSA UART platform driver\n");
 	return amba_driver_register(&pl011_driver);
 }
 
 static void __exit pl011_exit(void)
 {
+	platform_driver_unregister(&arm_sbsa_uart_platform_driver);
 	amba_driver_unregister(&pl011_driver);
 }
 
-- 
1.7.9.5

[PATCH v3 10/10] drivers: PL011: add support for the ARM SBSA generic UART

[Andre Przywara]

The ARM Server Base System Architecture[1] document describes a
generic UART which is a subset of the PL011 UART.
It lacks DMA support, baud rate control and modem status line
control, among other things.
The idea is to move the UART initialization and setup into the
firmware (which does this job today already) and let the kernel just
use the UART for sending and receiving characters.

We use the recent refactoring to build a new struct uart_ops
variable which points to some new functions avoiding access to the
missing registers. We reuse as much existing PL011 code as possible.

In contrast to the PL011 the SBSA UART does not define any AMBA or
PrimeCell relations, so we go with a pretty generic probe function
which only uses platform device functions.
A DT binding is provided, but other systems can easily attach to it,
too (hint, hint!).

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 .../devicetree/bindings/serial/arm_sbsa_uart.txt   |   10 ++
 drivers/tty/serial/amba-pl011.c                    |  165 ++++++++++++++++++++
 2 files changed, 175 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/serial/arm_sbsa_uart.txt

diff --git a/Documentation/devicetree/bindings/serial/arm_sbsa_uart.txt b/Documentation/devicetree/bindings/serial/arm_sbsa_uart.txt
new file mode 100644
index 0000000..4163e7e
--- /dev/null
+++ b/Documentation/devicetree/bindings/serial/arm_sbsa_uart.txt
@@ -0,0 +1,10 @@
+* ARM SBSA defined generic UART
+This UART uses a subset of the PL011 registers and consequently lives
+in the PL011 driver. It's baudrate and other communication parameters
+cannot be adjusted at runtime, so it lacks a clock specifier here.
+
+Required properties:
+- compatible: must be "arm,sbsa-uart"
+- reg: exactly one register range
+- interrupts: exactly one interrupt specifier
+- current-speed: the (fixed) baud rate set by the firmware
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index fcb95bd..27e2051 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -101,6 +101,14 @@ static struct vendor_data vendor_arm = {
 	.get_fifosize		= get_fifosize_arm,
 };
 
+static struct vendor_data vendor_sbsa = {
+	.oversampling		= false,
+	.dma_threshold		= false,
+	.cts_event_workaround	= false,
+	.always_enabled		= true,
+	.fixed_options		= true,
+};
+
 static unsigned int get_fifosize_st(struct amba_device *dev)
 {
 	return 64;
@@ -1641,6 +1649,30 @@ static int pl011_startup(struct uart_port *port)
 	return retval;
 }
 
+static int sbsa_uart_startup(struct uart_port *port)
+{
+	struct uart_amba_port *uap =
+		container_of(port, struct uart_amba_port, port);
+	int retval;
+
+	retval = pl011_hwinit(port);
+	if (retval)
+		return retval;
+
+	retval = pl011_allocate_irq(uap);
+	if (retval)
+		return retval;
+
+	/*
+	 * The SBSA UART does not support any modem status lines.
+	 */
+	uap->old_status = 0;
+
+	pl011_enable_interrupts(uap);
+
+	return 0;
+}
+
 static void pl011_shutdown_channel(struct uart_amba_port *uap,
 					unsigned int lcrh)
 {
@@ -1722,6 +1754,19 @@ static void pl011_shutdown(struct uart_port *port)
 		uap->port.ops->flush_buffer(port);
 }
 
+static void sbsa_uart_shutdown(struct uart_port *port)
+{
+	struct uart_amba_port *uap =
+		container_of(port, struct uart_amba_port, port);
+
+	pl011_disable_interrupts(uap);
+
+	free_irq(uap->port.irq, uap);
+
+	if (uap->port.ops->flush_buffer)
+		uap->port.ops->flush_buffer(port);
+}
+
 static void
 pl011_setup_status_masks(struct uart_port *port, struct ktermios *termios)
 {
@@ -1873,6 +1918,24 @@ pl011_set_termios(struct uart_port *port, struct ktermios *termios,
 	spin_unlock_irqrestore(&port->lock, flags);
 }
 
+static void
+sbsa_uart_set_termios(struct uart_port *port, struct ktermios *termios,
+		      struct ktermios *old)
+{
+	struct uart_amba_port *uap =
+	    container_of(port, struct uart_amba_port, port);
+	unsigned long flags;
+
+	if (old)
+		tty_termios_copy_hw(termios, old);
+	tty_termios_encode_baud_rate(termios, uap->fixed_baud, uap->fixed_baud);
+
+	spin_lock_irqsave(&port->lock, flags);
+	uart_update_timeout(port, CS8, uap->fixed_baud);
+	pl011_setup_status_masks(port, termios);
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
 static const char *pl011_type(struct uart_port *port)
 {
 	struct uart_amba_port *uap =
@@ -1948,6 +2011,37 @@ static struct uart_ops amba_pl011_pops = {
 #endif
 };
 
+static void sbsa_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+}
+
+static unsigned int sbsa_uart_get_mctrl(struct uart_port *port)
+{
+	return 0;
+}
+
+static struct uart_ops sbsa_uart_pops = {
+	.tx_empty	= pl011_tx_empty,
+	.set_mctrl	= sbsa_uart_set_mctrl,
+	.get_mctrl	= sbsa_uart_get_mctrl,
+	.stop_tx	= pl011_stop_tx,
+	.start_tx	= pl011_start_tx,
+	.stop_rx	= pl011_stop_rx,
+	.startup	= sbsa_uart_startup,
+	.shutdown	= sbsa_uart_shutdown,
+	.set_termios	= sbsa_uart_set_termios,
+	.type		= pl011_type,
+	.release_port	= pl011_release_port,
+	.request_port	= pl011_request_port,
+	.config_port	= pl011_config_port,
+	.verify_port	= pl011_verify_port,
+#ifdef CONFIG_CONSOLE_POLL
+	.poll_init     = pl011_hwinit,
+	.poll_get_char = pl011_get_poll_char,
+	.poll_put_char = pl011_put_poll_char,
+#endif
+};
+
 static struct uart_amba_port *amba_ports[UART_NR];
 
 #ifdef CONFIG_SERIAL_AMBA_PL011_CONSOLE
@@ -2334,6 +2428,74 @@ static int pl011_resume(struct device *dev)
 
 static SIMPLE_DEV_PM_OPS(pl011_dev_pm_ops, pl011_suspend, pl011_resume);
 
+static int sbsa_uart_probe(struct platform_device *pdev)
+{
+	struct uart_amba_port *uap;
+	struct resource *r;
+	int portnr, ret;
+	int baudrate;
+
+	/*
+	 * Check the mandatory baud rate parameter in the DT node early
+	 * so that we can easily exit with the error.
+	 */
+	if (pdev->dev.of_node) {
+		struct device_node *np = pdev->dev.of_node;
+
+		ret = of_property_read_u32(np, "current-speed", &baudrate);
+		if (ret)
+			return ret;
+	} else {
+		baudrate = 115200;
+	}
+
+	portnr = pl011_allocate_port(&pdev->dev, &uap);
+	if (portnr < 0)
+		return portnr;
+
+	uap->vendor	= &vendor_sbsa;
+	uap->fifosize	= 32;
+	uap->port.irq	= platform_get_irq(pdev, 0);
+	uap->port.ops	= &sbsa_uart_pops;
+	uap->fixed_baud = baudrate;
+
+	snprintf(uap->type, sizeof(uap->type), "SBSA");
+
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+
+	ret = pl011_setup_port(&pdev->dev, uap, r, portnr);
+	if (ret)
+		return ret;
+
+	platform_set_drvdata(pdev, uap);
+
+	return pl011_register_port(uap);
+}
+
+static int sbsa_uart_remove(struct platform_device *pdev)
+{
+	struct uart_amba_port *uap = platform_get_drvdata(pdev);
+
+	uart_remove_one_port(&amba_reg, &uap->port);
+	pl011_unregister_port(uap);
+	return 0;
+}
+
+static const struct of_device_id sbsa_uart_match[] = {
+	{ .compatible = "arm,sbsa-uart", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, sbsa_uart_match);
+
+static struct platform_driver arm_sbsa_uart_platform_driver = {
+	.probe		= sbsa_uart_probe,
+	.remove		= sbsa_uart_remove,
+	.driver	= {
+		.name	= "sbsa-uart",
+		.of_match_table = of_match_ptr(sbsa_uart_match),
+	},
+};
+
 static struct amba_id pl011_ids[] = {
 	{
 		.id	= 0x00041011,
@@ -2364,11 +2526,14 @@ static int __init pl011_init(void)
 {
 	printk(KERN_INFO "Serial: AMBA PL011 UART driver\n");
 
+	if (platform_driver_register(&arm_sbsa_uart_platform_driver))
+		pr_warn("could not register SBSA UART platform driver\n");
 	return amba_driver_register(&pl011_driver);
 }
 
 static void __exit pl011_exit(void)
 {
+	platform_driver_unregister(&arm_sbsa_uart_platform_driver);
 	amba_driver_unregister(&pl011_driver);
 }
 
-- 
1.7.9.5

Re: [PATCH v3 01/10] drivers: PL011: avoid potential unregister_driver call

[Jakub Kiciński]

On Thu,  9 Apr 2015 12:29:12 +0100, Andre Przywara wrote:
> Although we care about not unregistering the driver if there are
> still ports connected during the .remove callback, we do miss this
> check in the pl011_probe function. So if the current port allocation
> fails, but there are other ports already registered, we will kill
> those.
> So factor out the port removal into a separate function and use that
> in the probe function, too.
> 
> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> ---
>  drivers/tty/serial/amba-pl011.c |   37 +++++++++++++++++++++----------------
>  1 file changed, 21 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
> index f5bd842..d08951f 100644
> --- a/drivers/tty/serial/amba-pl011.c
> +++ b/drivers/tty/serial/amba-pl011.c
> @@ -2135,6 +2135,24 @@ static int pl011_probe_dt_alias(int index, struct device *dev)
>  	return ret;
>  }
>  
> +/* unregisters the driver also if no more ports are left */
> +static void pl011_unregister_port(struct uart_amba_port *uap)
> +{
> +	int i;
> +	bool busy = false;
> +
> +	for (i = 0; i < ARRAY_SIZE(amba_ports); i++) {
> +		if (amba_ports[i] == uap)
> +			amba_ports[i] = NULL;
> +		else if (amba_ports[i])
> +			busy = true;
> +	}
> +	pl011_dma_remove(uap);
> +	if (!busy)
> +		uart_unregister_driver(&amba_reg);
> +}
> +
> +

Double new line.

[PATCH v3 01/10] drivers: PL011: avoid potential unregister_driver call

[Jakub Kiciński]

On Thu,  9 Apr 2015 12:29:12 +0100, Andre Przywara wrote:
> Although we care about not unregistering the driver if there are
> still ports connected during the .remove callback, we do miss this
> check in the pl011_probe function. So if the current port allocation
> fails, but there are other ports already registered, we will kill
> those.
> So factor out the port removal into a separate function and use that
> in the probe function, too.
> 
> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> ---
>  drivers/tty/serial/amba-pl011.c |   37 +++++++++++++++++++++----------------
>  1 file changed, 21 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
> index f5bd842..d08951f 100644
> --- a/drivers/tty/serial/amba-pl011.c
> +++ b/drivers/tty/serial/amba-pl011.c
> @@ -2135,6 +2135,24 @@ static int pl011_probe_dt_alias(int index, struct device *dev)
>  	return ret;
>  }
>  
> +/* unregisters the driver also if no more ports are left */
> +static void pl011_unregister_port(struct uart_amba_port *uap)
> +{
> +	int i;
> +	bool busy = false;
> +
> +	for (i = 0; i < ARRAY_SIZE(amba_ports); i++) {
> +		if (amba_ports[i] == uap)
> +			amba_ports[i] = NULL;
> +		else if (amba_ports[i])
> +			busy = true;
> +	}
> +	pl011_dma_remove(uap);
> +	if (!busy)
> +		uart_unregister_driver(&amba_reg);
> +}
> +
> +

Double new line.

Re: [PATCH v3 03/10] drivers: PL011: refactor pl011_shutdown()

[Jakub Kiciński]

On Thu,  9 Apr 2015 12:29:14 +0100, Andre Przywara wrote:
> Split the pl011_shutdown() function into smaller chunks to allow
> easier reuse later when adding SBSA support.
> 
> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> ---
>  drivers/tty/serial/amba-pl011.c |   58 ++++++++++++++++++++++-----------------
>  1 file changed, 33 insertions(+), 25 deletions(-)
> 
> diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
> index d6a081e..9eb6d13 100644
> --- a/drivers/tty/serial/amba-pl011.c
> +++ b/drivers/tty/serial/amba-pl011.c
> @@ -1635,34 +1635,15 @@ static void pl011_shutdown_channel(struct uart_amba_port *uap,
>        writew(val, uap->port.membase + lcrh);
>  }
>  
> -static void pl011_shutdown(struct uart_port *port)
> +/*
> + * disable the port. It should not disable RTS and DTR.
> + * Also RTS and DTR state should be preserved to restore
> + * it during startup().
> + */
> +static void pl011_disable_uart(struct uart_amba_port *uap)
>  {
> -	struct uart_amba_port *uap =
> -	    container_of(port, struct uart_amba_port, port);
>  	unsigned int cr;
>  
> -	/*
> -	 * disable all interrupts
> -	 */
> -	spin_lock_irq(&uap->port.lock);
> -	uap->im = 0;
> -	writew(uap->im, uap->port.membase + UART011_IMSC);
> -	writew(0xffff, uap->port.membase + UART011_ICR);
> -	spin_unlock_irq(&uap->port.lock);
> -
> -	pl011_dma_shutdown(uap);
> -
> -	/*
> -	 * Free the interrupt
> -	 */
> -	free_irq(uap->port.irq, uap);
> -
> -	/*
> -	 * disable the port
> -	 * disable the port. It should not disable RTS and DTR.
> -	 * Also RTS and DTR state should be preserved to restore
> -	 * it during startup().
> -	 */
>  	uap->autorts = false;
>  	spin_lock_irq(&uap->port.lock);
>  	cr = readw(uap->port.membase + UART011_CR);
> @@ -1678,6 +1659,33 @@ static void pl011_shutdown(struct uart_port *port)
>  	pl011_shutdown_channel(uap, uap->lcrh_rx);
>  	if (uap->lcrh_rx != uap->lcrh_tx)
>  		pl011_shutdown_channel(uap, uap->lcrh_tx);
> +}
> +
> +static void pl011_disable_interrupts(struct uart_amba_port *uap)
> +{
> +	spin_lock_irq(&uap->port.lock);
> +	/*
> +	 * mask all interrupts and clear all pending ones
> +	 */

No need for a multi-line comment here.

> +	uap->im = 0;
> +	writew(uap->im, uap->port.membase + UART011_IMSC);
> +	writew(0xffff & ~UART011_TXIS, uap->port.membase + UART011_ICR);

The line you removed was:
	writew(0xffff, uap->port.membase + UART011_ICR);

Please rebase more carefully.

[PATCH v3 03/10] drivers: PL011: refactor pl011_shutdown()

[Jakub Kiciński]

On Thu,  9 Apr 2015 12:29:14 +0100, Andre Przywara wrote:
> Split the pl011_shutdown() function into smaller chunks to allow
> easier reuse later when adding SBSA support.
> 
> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> ---
>  drivers/tty/serial/amba-pl011.c |   58 ++++++++++++++++++++++-----------------
>  1 file changed, 33 insertions(+), 25 deletions(-)
> 
> diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
> index d6a081e..9eb6d13 100644
> --- a/drivers/tty/serial/amba-pl011.c
> +++ b/drivers/tty/serial/amba-pl011.c
> @@ -1635,34 +1635,15 @@ static void pl011_shutdown_channel(struct uart_amba_port *uap,
>        writew(val, uap->port.membase + lcrh);
>  }
>  
> -static void pl011_shutdown(struct uart_port *port)
> +/*
> + * disable the port. It should not disable RTS and DTR.
> + * Also RTS and DTR state should be preserved to restore
> + * it during startup().
> + */
> +static void pl011_disable_uart(struct uart_amba_port *uap)
>  {
> -	struct uart_amba_port *uap =
> -	    container_of(port, struct uart_amba_port, port);
>  	unsigned int cr;
>  
> -	/*
> -	 * disable all interrupts
> -	 */
> -	spin_lock_irq(&uap->port.lock);
> -	uap->im = 0;
> -	writew(uap->im, uap->port.membase + UART011_IMSC);
> -	writew(0xffff, uap->port.membase + UART011_ICR);
> -	spin_unlock_irq(&uap->port.lock);
> -
> -	pl011_dma_shutdown(uap);
> -
> -	/*
> -	 * Free the interrupt
> -	 */
> -	free_irq(uap->port.irq, uap);
> -
> -	/*
> -	 * disable the port
> -	 * disable the port. It should not disable RTS and DTR.
> -	 * Also RTS and DTR state should be preserved to restore
> -	 * it during startup().
> -	 */
>  	uap->autorts = false;
>  	spin_lock_irq(&uap->port.lock);
>  	cr = readw(uap->port.membase + UART011_CR);
> @@ -1678,6 +1659,33 @@ static void pl011_shutdown(struct uart_port *port)
>  	pl011_shutdown_channel(uap, uap->lcrh_rx);
>  	if (uap->lcrh_rx != uap->lcrh_tx)
>  		pl011_shutdown_channel(uap, uap->lcrh_tx);
> +}
> +
> +static void pl011_disable_interrupts(struct uart_amba_port *uap)
> +{
> +	spin_lock_irq(&uap->port.lock);
> +	/*
> +	 * mask all interrupts and clear all pending ones
> +	 */

No need for a multi-line comment here.

> +	uap->im = 0;
> +	writew(uap->im, uap->port.membase + UART011_IMSC);
> +	writew(0xffff & ~UART011_TXIS, uap->port.membase + UART011_ICR);

The line you removed was:
	writew(0xffff, uap->port.membase + UART011_ICR);

Please rebase more carefully.

Re: [PATCH v3 05/10] drivers: PL011: refactor pl011_probe()

[Jakub Kiciński]

On Thu,  9 Apr 2015 12:29:16 +0100, Andre Przywara wrote:
> Currently the pl011_probe() function is relying on some AMBA IDs
> and a device tree node to initialize the driver and a port.
> Both features are not necessarily required for the driver:
> - we lack AMBA IDs in the ARM SBSA generic UART and
> - we lack a DT node in ACPI systems.
> So lets refactor the function to ease later reuse.
> 
> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> ---
>  drivers/tty/serial/amba-pl011.c |   89 ++++++++++++++++++++++++++-------------
>  1 file changed, 60 insertions(+), 29 deletions(-)
> 
> diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
> index e1ac2cb..65df5c7 100644
> --- a/drivers/tty/serial/amba-pl011.c
> +++ b/drivers/tty/serial/amba-pl011.c
> @@ -2174,13 +2174,10 @@ static void pl011_unregister_port(struct uart_amba_port *uap)
>  		uart_unregister_driver(&amba_reg);
>  }
>  
> -
> -static int pl011_probe(struct amba_device *dev, const struct amba_id *id)
> +static int pl011_allocate_port(struct device *dev, struct uart_amba_port **_uap)
>  {
>  	struct uart_amba_port *uap;
> -	struct vendor_data *vendor = id->data;
> -	void __iomem *base;
> -	int i, ret;
> +	int i;
>  
>  	for (i = 0; i < ARRAY_SIZE(amba_ports); i++)
>  		if (amba_ports[i] == NULL)
> @@ -2189,51 +2186,53 @@ static int pl011_probe(struct amba_device *dev, const struct amba_id *id)
>  	if (i == ARRAY_SIZE(amba_ports))
>  		return -EBUSY;
>  
> -	uap = devm_kzalloc(&dev->dev, sizeof(struct uart_amba_port),
> -			   GFP_KERNEL);
> +	uap = devm_kzalloc(dev, sizeof(struct uart_amba_port), GFP_KERNEL);
>  	if (uap == NULL)
>  		return -ENOMEM;
>  
> -	i = pl011_probe_dt_alias(i, &dev->dev);
> +	if (_uap)
> +		*_uap = uap;
> +
> +	return i;
> +}

Could we please move the allocation out of this function and spare
ourselves the "out argument".  It's just a matter of personal
preference so the final decision is up to you.

Also you never pass _uap as NULL so the check is unnecessary.

[PATCH v3 05/10] drivers: PL011: refactor pl011_probe()

[Jakub Kiciński]

On Thu,  9 Apr 2015 12:29:16 +0100, Andre Przywara wrote:
> Currently the pl011_probe() function is relying on some AMBA IDs
> and a device tree node to initialize the driver and a port.
> Both features are not necessarily required for the driver:
> - we lack AMBA IDs in the ARM SBSA generic UART and
> - we lack a DT node in ACPI systems.
> So lets refactor the function to ease later reuse.
> 
> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> ---
>  drivers/tty/serial/amba-pl011.c |   89 ++++++++++++++++++++++++++-------------
>  1 file changed, 60 insertions(+), 29 deletions(-)
> 
> diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
> index e1ac2cb..65df5c7 100644
> --- a/drivers/tty/serial/amba-pl011.c
> +++ b/drivers/tty/serial/amba-pl011.c
> @@ -2174,13 +2174,10 @@ static void pl011_unregister_port(struct uart_amba_port *uap)
>  		uart_unregister_driver(&amba_reg);
>  }
>  
> -
> -static int pl011_probe(struct amba_device *dev, const struct amba_id *id)
> +static int pl011_allocate_port(struct device *dev, struct uart_amba_port **_uap)
>  {
>  	struct uart_amba_port *uap;
> -	struct vendor_data *vendor = id->data;
> -	void __iomem *base;
> -	int i, ret;
> +	int i;
>  
>  	for (i = 0; i < ARRAY_SIZE(amba_ports); i++)
>  		if (amba_ports[i] == NULL)
> @@ -2189,51 +2186,53 @@ static int pl011_probe(struct amba_device *dev, const struct amba_id *id)
>  	if (i == ARRAY_SIZE(amba_ports))
>  		return -EBUSY;
>  
> -	uap = devm_kzalloc(&dev->dev, sizeof(struct uart_amba_port),
> -			   GFP_KERNEL);
> +	uap = devm_kzalloc(dev, sizeof(struct uart_amba_port), GFP_KERNEL);
>  	if (uap == NULL)
>  		return -ENOMEM;
>  
> -	i = pl011_probe_dt_alias(i, &dev->dev);
> +	if (_uap)
> +		*_uap = uap;
> +
> +	return i;
> +}

Could we please move the allocation out of this function and spare
ourselves the "out argument".  It's just a matter of personal
preference so the final decision is up to you.

Also you never pass _uap as NULL so the check is unnecessary.