drivers: uart_pl011: Enable shared interrupts support

The PrimeCell UART (PL011) IP can use one single combined/shared
interrupt line instead than different IRQ lines for TX/RX/Err/... This
is the most common configuration supported in the Linux world but not
currently supported in Zephyr. QEMU emulates a PL011 UART with a single
interrupt line as well.

To support this configuration we have to hookup the PL011 driver with a
shared IRQ driver and add two new configuration options when the shared
IRQ line is used.

Signed-off-by: Carlo Caione <ccaione@baylibre.com>

drivers/serial/Kconfig.pl011

@@ -20,4 +20,25 @@ config UART_PL011_PORT1
 	help
 	  Build the driver to utilize UART controller Port 1.
 
+config UART_PL011_SHARED_IRQ
+	bool
+
+config UART_PL011_PORT0_SHARED_IRQ
+	bool "Shared IRQ for UART 0"
+	depends on SHARED_IRQ_0
+	depends on UART_PL011_PORT0
+	select UART_PL011_SHARED_IRQ
+	help
+	  When interrupts fire, the shared IRQ driver is notified. Then the shared IRQ
+	  driver dispatches the interrupt to the UART driver.
+
+config UART_PL011_PORT1_SHARED_IRQ
+	bool "Shared IRQ for UART 1"
+	depends on SHARED_IRQ_1
+	depends on UART_PL011_PORT1
+	select UART_PL011_SHARED_IRQ
+	help
+	  When interrupts fire, the shared IRQ driver is notified. Then the shared IRQ
+	  driver dispatches the interrupt to the UART driver.
+
 endif # UART_PL011

drivers/serial/uart_pl011.c

@@ -11,6 +11,9 @@
 #include <soc.h>
 #include <drivers/uart.h>
 
+#if defined(CONFIG_SHARED_IRQ)
+#include <shared_irq.h>
+#endif
 
 /*
  * UART PL011 register map structure
@@ -43,6 +46,9 @@ struct pl011_data {
 #ifdef CONFIG_UART_INTERRUPT_DRIVEN
 	uart_irq_callback_user_data_t irq_cb;
 	void *irq_cb_data;
+#if defined(CONFIG_UART_PL011_SHARED_IRQ)
+	char *shared_irq_dev_name;
+#endif
 #endif
 };
 
@@ -423,6 +429,9 @@ static struct uart_device_config pl011_cfg_port_0 = {
 
 static struct pl011_data pl011_data_port_0 = {
 	.baud_rate = DT_PL011_PORT0_BAUD_RATE,
+#if defined(CONFIG_UART_PL011_SHARED_IRQ)
+	.shared_irq_dev_name = DT_INST_0_SHARED_IRQ_LABEL,
+#endif
 };
 
 DEVICE_AND_API_INIT(pl011_port_0,
@@ -436,6 +445,14 @@ DEVICE_AND_API_INIT(pl011_port_0,
 #ifdef CONFIG_UART_INTERRUPT_DRIVEN
 static void pl011_irq_config_func_0(struct device *dev)
 {
+#if defined(CONFIG_UART_PL011_PORT0_SHARED_IRQ)
+	struct device *shared_irq_dev;
+
+	shared_irq_dev = device_get_binding(DEV_DATA(dev)->shared_irq_dev_name);
+	__ASSERT(shared_irq_dev != NULL, "Failed to get shared irq");
+	shared_irq_isr_register(shared_irq_dev, (isr_t)pl011_isr, dev);
+	shared_irq_enable(shared_irq_dev, dev);
+#else
 	IRQ_CONNECT(DT_PL011_PORT0_IRQ_TX,
 		    DT_PL011_PORT0_IRQ_PRI,
 		    pl011_isr,
@@ -456,6 +473,7 @@ static void pl011_irq_config_func_0(struct device *dev)
 		    DEVICE_GET(pl011_port_0),
 		    0);
 	irq_enable(DT_PL011_PORT0_IRQ_RXTIM);
+#endif
 }
 #endif
 
@@ -477,6 +495,9 @@ static struct uart_device_config pl011_cfg_port_1 = {
 
 static struct pl011_data pl011_data_port_1 = {
 	.baud_rate = DT_PL011_PORT1_BAUD_RATE,
+#if defined(CONFIG_UART_PL011_SHARED_IRQ)
+	.shared_irq_dev_name = DT_INST_1_SHARED_IRQ_LABEL,
+#endif
 };
 
 DEVICE_AND_API_INIT(pl011_port_1,
@@ -490,6 +511,14 @@ DEVICE_AND_API_INIT(pl011_port_1,
 #ifdef CONFIG_UART_INTERRUPT_DRIVEN
 static void pl011_irq_config_func_1(struct device *dev)
 {
+#if defined(CONFIG_UART_PL011_PORT1_SHARED_IRQ)
+	struct device *shared_irq_dev;
+
+	shared_irq_dev = device_get_binding(DEV_DATA(dev)->shared_irq_dev_name);
+	__ASSERT(shared_irq_dev != NULL, "Failed to get shared irq");
+	shared_irq_isr_register(shared_irq_dev, (isr_t)pl011_isr, dev);
+	shared_irq_enable(shared_irq_dev, dev);
+#else
 	IRQ_CONNECT(DT_PL011_PORT1_IRQ_TX,
 		    DT_PL011_PORT1_IRQ_PRI,
 		    pl011_isr,
@@ -510,6 +539,7 @@ static void pl011_irq_config_func_1(struct device *dev)
 		    DEVICE_GET(pl011_port_1),
 		    0);
 	irq_enable(DT_PL011_PORT1_IRQ_RXTIM);
+#endif
 }
 #endif