[PATCH v2 2/4] tegra, serial8250: add ->handle_break() uart_port op

[Dan Williams <dan.j.williams@intel.com>]

The "KT" serial port has another use case for a "received break" quirk,
so before adding another special case to the 8250 core take this
opportunity to push such quirks out of the core and into a uart_port op.

Stephen says:
"If the callback function is to no longer live in 8250.c itself,
 arch/arm/mach-tegra/devices.c isn't logically a good place to put it,
 and that file will be going away once we get rid of all the board files
 and move solely to device tree."

...so since 8250_pci.c houses all the quirks for pci serial devices this
quirk is similarly housed in of_serial.c.  Once the open firmware
conversion completes the infrastructure details (CONFIG_TEGRA_SERIAL,
include/linux/of_serial.h, and the export) can all be removed to make
this self contained to of_serial.c.

Cc: Nhan H Mai <nhan.h.mai@intel.com>
Cc: Colin Cross <ccross@android.com>
Cc: Olof Johansson <olof@lixom.net>
Cc: Stephen Warren <swarren@nvidia.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Sudhakar Mamillapalli <sudhakar@fb.com>
Reported-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 arch/arm/configs/tegra_defconfig      |    1 +
 arch/arm/mach-tegra/board-harmony.c   |    4 ++++
 arch/arm/mach-tegra/board-paz00.c     |    5 +++++
 arch/arm/mach-tegra/board-seaboard.c  |    4 ++++
 arch/arm/mach-tegra/board-trimslice.c |    4 ++++
 arch/arm/mach-tegra/devices.h         |    1 -
 drivers/tty/serial/8250/8250.c        |   34 +++------------------------------
 drivers/tty/serial/Kconfig            |    8 ++++++++
 drivers/tty/serial/of_serial.c        |   29 +++++++++++++++++++++++++++-
 include/linux/of_serial.h             |   17 +++++++++++++++++
 include/linux/serial_8250.h           |    1 +
 include/linux/serial_core.h           |    5 +++++
 12 files changed, 80 insertions(+), 33 deletions(-)
 create mode 100644 include/linux/of_serial.h

diff --git a/arch/arm/configs/tegra_defconfig b/arch/arm/configs/tegra_defconfig
index 351d670..de7288a 100644
--- a/arch/arm/configs/tegra_defconfig
+++ b/arch/arm/configs/tegra_defconfig
@@ -97,6 +97,7 @@ CONFIG_INPUT_EVDEV=y
 CONFIG_SERIAL_8250=y
 CONFIG_SERIAL_8250_CONSOLE=y
 CONFIG_SERIAL_OF_PLATFORM=y
+CONFIG_SERIAL_TEGRA=y
 # CONFIG_HW_RANDOM is not set
 CONFIG_I2C=y
 # CONFIG_I2C_COMPAT is not set
diff --git a/arch/arm/mach-tegra/board-harmony.c b/arch/arm/mach-tegra/board-harmony.c
index c00aadb..b8ceac3 100644
--- a/arch/arm/mach-tegra/board-harmony.c
+++ b/arch/arm/mach-tegra/board-harmony.c
@@ -19,6 +19,7 @@
 #include <linux/init.h>
 #include <linux/platform_device.h>
 #include <linux/serial_8250.h>
+#include <linux/of_serial.h>
 #include <linux/clk.h>
 #include <linux/dma-mapping.h>
 #include <linux/pda_power.h>
@@ -52,6 +53,7 @@ static struct plat_serial8250_port debug_uart_platform_data[] = {
 		.irq		= INT_UARTD,
 		.flags		= UPF_BOOT_AUTOCONF | UPF_FIXED_TYPE,
 		.type		= PORT_TEGRA,
+		.handle_break	= tegra_serial_handle_break,
 		.iotype		= UPIO_MEM,
 		.regshift	= 2,
 		.uartclk	= 216000000,
@@ -115,7 +117,9 @@ static void __init harmony_i2c_init(void)
 }
 
 static struct platform_device *harmony_devices[] __initdata = {
+#if IS_ENABLED(CONFIG_SERIAL_TEGRA)
 	&debug_uart,
+#endif
 	&tegra_sdhci_device1,
 	&tegra_sdhci_device2,
 	&tegra_sdhci_device4,
diff --git a/arch/arm/mach-tegra/board-paz00.c b/arch/arm/mach-tegra/board-paz00.c
index 330afdf..1113dab 100644
--- a/arch/arm/mach-tegra/board-paz00.c
+++ b/arch/arm/mach-tegra/board-paz00.c
@@ -21,6 +21,7 @@
 #include <linux/init.h>
 #include <linux/platform_device.h>
 #include <linux/serial_8250.h>
+#include <linux/of_serial.h>
 #include <linux/clk.h>
 #include <linux/dma-mapping.h>
 #include <linux/gpio_keys.h>
@@ -55,6 +56,7 @@ static struct plat_serial8250_port debug_uart_platform_data[] = {
 		.irq		= INT_UARTA,
 		.flags		= UPF_BOOT_AUTOCONF | UPF_FIXED_TYPE,
 		.type		= PORT_TEGRA,
+		.handle_break	= tegra_serial_handle_break,
 		.iotype		= UPIO_MEM,
 		.regshift	= 2,
 		.uartclk	= 216000000,
@@ -65,6 +67,7 @@ static struct plat_serial8250_port debug_uart_platform_data[] = {
 		.irq		= INT_UARTC,
 		.flags		= UPF_BOOT_AUTOCONF | UPF_FIXED_TYPE,
 		.type		= PORT_TEGRA,
+		.handle_break	= tegra_serial_handle_break,
 		.iotype		= UPIO_MEM,
 		.regshift	= 2,
 		.uartclk	= 216000000,
@@ -142,7 +145,9 @@ static struct platform_device gpio_keys_device = {
 };
 
 static struct platform_device *paz00_devices[] __initdata = {
+#if IS_ENABLED(CONFIG_SERIAL_TEGRA)
 	&debug_uart,
+#endif
 	&tegra_sdhci_device4,
 	&tegra_sdhci_device1,
 	&wifi_rfkill_device,
diff --git a/arch/arm/mach-tegra/board-seaboard.c b/arch/arm/mach-tegra/board-seaboard.c
index d669847..59a30ab 100644
--- a/arch/arm/mach-tegra/board-seaboard.c
+++ b/arch/arm/mach-tegra/board-seaboard.c
@@ -18,6 +18,7 @@
 #include <linux/init.h>
 #include <linux/platform_device.h>
 #include <linux/serial_8250.h>
+#include <linux/of_serial.h>
 #include <linux/i2c.h>
 #include <linux/delay.h>
 #include <linux/input.h>
@@ -47,6 +48,7 @@ static struct plat_serial8250_port debug_uart_platform_data[] = {
 		/* Memory and IRQ filled in before registration */
 		.flags		= UPF_BOOT_AUTOCONF | UPF_FIXED_TYPE,
 		.type		= PORT_TEGRA,
+		.handle_break	= tegra_serial_handle_break,
 		.iotype		= UPIO_MEM,
 		.regshift	= 2,
 		.uartclk	= 216000000,
@@ -145,7 +147,9 @@ static struct platform_device seaboard_audio_device = {
 };
 
 static struct platform_device *seaboard_devices[] __initdata = {
+#if IS_ENABLED(CONFIG_SERIAL_TEGRA)
 	&debug_uart,
+#endif
 	&tegra_pmu_device,
 	&tegra_sdhci_device4,
 	&tegra_sdhci_device3,
diff --git a/arch/arm/mach-tegra/board-trimslice.c b/arch/arm/mach-tegra/board-trimslice.c
index cd52820..b156f55 100644
--- a/arch/arm/mach-tegra/board-trimslice.c
+++ b/arch/arm/mach-tegra/board-trimslice.c
@@ -22,6 +22,7 @@
 #include <linux/init.h>
 #include <linux/platform_device.h>
 #include <linux/serial_8250.h>
+#include <linux/of_serial.h>
 #include <linux/io.h>
 #include <linux/i2c.h>
 #include <linux/gpio.h>
@@ -48,6 +49,7 @@ static struct plat_serial8250_port debug_uart_platform_data[] = {
 		.irq		= INT_UARTA,
 		.flags		= UPF_BOOT_AUTOCONF | UPF_FIXED_TYPE,
 		.type		= PORT_TEGRA,
+		.handle_break	= tegra_serial_handle_break,
 		.iotype		= UPIO_MEM,
 		.regshift	= 2,
 		.uartclk	= 216000000,
@@ -81,7 +83,9 @@ static struct platform_device trimslice_audio_device = {
 };
 
 static struct platform_device *trimslice_devices[] __initdata = {
+#if IS_ENABLED(CONFIG_SERIAL_TEGRA)
 	&debug_uart,
+#endif
 	&tegra_sdhci_device1,
 	&tegra_sdhci_device4,
 	&tegra_i2s_device1,
diff --git a/arch/arm/mach-tegra/devices.h b/arch/arm/mach-tegra/devices.h
index ec45567..6e5f852 100644
--- a/arch/arm/mach-tegra/devices.h
+++ b/arch/arm/mach-tegra/devices.h
@@ -53,5 +53,4 @@ extern struct platform_device tegra_i2s_device1;
 extern struct platform_device tegra_i2s_device2;
 extern struct platform_device tegra_das_device;
 extern struct platform_device tegra_pcm_device;
-
 #endif
diff --git a/drivers/tty/serial/8250/8250.c b/drivers/tty/serial/8250/8250.c
index 5c27f7e..cbd94c3 100644
--- a/drivers/tty/serial/8250/8250.c
+++ b/drivers/tty/serial/8250/8250.c
@@ -1332,27 +1332,6 @@ static void serial8250_enable_ms(struct uart_port *port)
 }
 
 /*
- * Clear the Tegra rx fifo after a break
- *
- * FIXME: This needs to become a port specific callback once we have a
- * framework for this
- */
-static void clear_rx_fifo(struct uart_8250_port *up)
-{
-	unsigned int status, tmout = 10000;
-	do {
-		status = serial_in(up, UART_LSR);
-		if (status & (UART_LSR_FIFOE | UART_LSR_BRK_ERROR_BITS))
-			status = serial_in(up, UART_RX);
-		else
-			break;
-		if (--tmout == 0)
-			break;
-		udelay(1);
-	} while (1);
-}
-
-/*
  * serial8250_rx_chars: processes according to the passed in LSR
  * value, and returns the remaining LSR bits not handled
  * by this Rx routine.
@@ -1386,20 +1365,10 @@ serial8250_rx_chars(struct uart_8250_port *up, unsigned char lsr)
 		up->lsr_saved_flags = 0;
 
 		if (unlikely(lsr & UART_LSR_BRK_ERROR_BITS)) {
-			/*
-			 * For statistics only
-			 */
 			if (lsr & UART_LSR_BI) {
 				lsr &= ~(UART_LSR_FE | UART_LSR_PE);
 				port->icount.brk++;
 				/*
-				 * If tegra port then clear the rx fifo to
-				 * accept another break/character.
-				 */
-				if (port->type == PORT_TEGRA)
-					clear_rx_fifo(up);
-
-				/*
 				 * We do the SysRQ and SAK checking
 				 * here because otherwise the break
 				 * may get masked by ignore_status_mask
@@ -3037,6 +3006,7 @@ static int __devinit serial8250_probe(struct platform_device *dev)
 		port.serial_in		= p->serial_in;
 		port.serial_out		= p->serial_out;
 		port.handle_irq		= p->handle_irq;
+		port.handle_break	= p->handle_break;
 		port.set_termios	= p->set_termios;
 		port.pm			= p->pm;
 		port.dev		= &dev->dev;
@@ -3209,6 +3179,8 @@ int serial8250_register_port(struct uart_port *port)
 			uart->port.set_termios = port->set_termios;
 		if (port->pm)
 			uart->port.pm = port->pm;
+		if (port->handle_break)
+			uart->port.handle_break = port->handle_break;
 
 		if (serial8250_isa_config != NULL)
 			serial8250_isa_config(0, &uart->port,
diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index 665beb6..33fa6ec 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -380,6 +380,14 @@ config SERIAL_PXA_CONSOLE
 	  your boot loader (lilo or loadlin) about how to pass options to the
 	  kernel at boot time.)
 
+# FIXME remove this option when Tegra completes conversion to open firmware
+config SERIAL_TEGRA
+	bool "Tegra serial port support"
+	depends on SERIAL_OF_PLATFORM=y
+	help
+	  If you have a machine based on NVIDIA Tegra you can enable its
+	  onboard serial ports by enabling this option.
+
 config SERIAL_SA1100
 	bool "SA1100 serial port support"
 	depends on ARM && ARCH_SA1100
diff --git a/drivers/tty/serial/of_serial.c b/drivers/tty/serial/of_serial.c
index 4621cf9..5a3b3f6 100644
--- a/drivers/tty/serial/of_serial.c
+++ b/drivers/tty/serial/of_serial.c
@@ -12,8 +12,10 @@
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/slab.h>
+#include <linux/delay.h>
 #include <linux/serial_core.h>
 #include <linux/serial_8250.h>
+#include <linux/serial_reg.h>
 #include <linux/of_address.h>
 #include <linux/of_irq.h>
 #include <linux/of_platform.h>
@@ -168,6 +170,31 @@ static int of_platform_serial_remove(struct platform_device *ofdev)
 	return 0;
 }
 
+#if IS_ENABLED(CONFIG_SERIAL_TEGRA)
+void tegra_serial_handle_break(struct uart_port *p)
+{
+	unsigned int status, tmout = 10000;
+
+	do {
+		status = p->serial_in(p, UART_LSR);
+		if (status & (UART_LSR_FIFOE | UART_LSR_BRK_ERROR_BITS))
+			status = p->serial_in(p, UART_RX);
+		else
+			break;
+		if (--tmout == 0)
+			break;
+		udelay(1);
+	} while (1);
+}
+/* FIXME remove this export when tegra finishes conversion to open firmware */
+EXPORT_SYMBOL_GPL(tegra_serial_handle_break);
+#endif
+
+static void tegra_setup_quirk(struct uart_port *port)
+{
+	port->handle_break = tegra_serial_handle_break;
+}
+
 /*
  * contiguous OF_ number space for serial port types so the
  * __sinfo array does not have holes, and to allow cases of:
@@ -192,7 +219,7 @@ static struct of_serial_info __refdata __sinfo[] = {
 	[OF_PORT_16550] = { .type = PORT_16550, },
 	[OF_PORT_16750] = { .type = PORT_16750, },
 	[OF_PORT_16850] = { .type = PORT_16850, },
-	[OF_PORT_TEGRA] = { .type = PORT_TEGRA, },
+	[OF_PORT_TEGRA] = { .type = PORT_TEGRA, .setup = tegra_setup_quirk, },
 	[OF_PORT_NWPSERIAL] = { .type = PORT_NWPSERIAL, },
 	[OF_PORT_UNKNOWN] = { .type = PORT_UNKNOWN,  },
 };
diff --git a/include/linux/of_serial.h b/include/linux/of_serial.h
new file mode 100644
index 0000000..2035d96
--- /dev/null
+++ b/include/linux/of_serial.h
@@ -0,0 +1,17 @@
+#ifndef __LINUX_OF_SERIAL_H
+#define __LINUX_OF_SERIAL_H
+
+/*
+ * FIXME remove this file when tegra finishes conversion to open firmware,
+ * expectation is that all quirks will then be self-contained in
+ * drivers/tty/serial/of_serial.c.
+ */
+#if IS_ENABLED(CONFIG_SERIAL_TEGRA)
+extern void tegra_serial_handle_break(struct uart_port *port);
+#else
+static inline void tegra_serial_handle_break(struct uart_port *port)
+{
+}
+#endif
+
+#endif /* __LINUX_OF_SERIAL */
diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h
index 8f012f8..a522fd9 100644
--- a/include/linux/serial_8250.h
+++ b/include/linux/serial_8250.h
@@ -38,6 +38,7 @@ struct plat_serial8250_port {
 	int		(*handle_irq)(struct uart_port *);
 	void		(*pm)(struct uart_port *, unsigned int state,
 			      unsigned old);
+	void		(*handle_break)(struct uart_port *);
 };
 
 /*
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 2db407a..65db992 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -310,6 +310,7 @@ struct uart_port {
 	int			(*handle_irq)(struct uart_port *);
 	void			(*pm)(struct uart_port *, unsigned int state,
 				      unsigned int old);
+	void			(*handle_break)(struct uart_port *);
 	unsigned int		irq;			/* irq number */
 	unsigned long		irqflags;		/* irq flags  */
 	unsigned int		uartclk;		/* base uart clock */
@@ -533,6 +534,10 @@ uart_handle_sysrq_char(struct uart_port *port, unsigned int ch)
 static inline int uart_handle_break(struct uart_port *port)
 {
 	struct uart_state *state = port->state;
+
+	if (port->handle_break)
+		port->handle_break(port);
+
 #ifdef SUPPORT_SYSRQ
 	if (port->cons && port->cons->index == port->line) {
 		if (!port->sysrq) {