[PATCH] bsp/raspberrypi: AUX uart driver

[G S Niteesh]

This patch adds the driver for aux driver present in Raspberry
Pi 3 and above, this uart is currently used as the primary uart.
The AUX uart is similar to ns16550, it uses the libchip/ns16550
driver.
---
 bsps/arm/raspberrypi/console/console-config.c | 113 ++++++++++++++++--
 bsps/arm/raspberrypi/include/bsp/usart.h      |   1 +
 2 files changed, 107 insertions(+), 7 deletions(-)

diff --git a/bsps/arm/raspberrypi/console/console-config.c b/bsps/arm/raspberrypi/console/console-config.c
index 48c4c6a3ec7..6ff018fb8ef 100644
--- a/bsps/arm/raspberrypi/console/console-config.c
+++ b/bsps/arm/raspberrypi/console/console-config.c
@@ -24,6 +24,7 @@
 
 #include <libchip/serial.h>
 #include <libfdt.h>
+#include <libchip/ns16550.h>
 
 #include <bspopts.h>
 #include <bsp/usart.h>
@@ -34,35 +35,103 @@
 #include <bsp/console-termios.h>
 #include <bsp/fdt.h>
 #include <bsp/fatal.h>
+#include <bsp/gpio.h>
+#include <bsp/rpi-gpio.h>
 
-
+/**
+ * UART0 - PL011
+ * UART1 - AUX UART
+ */
 #define UART0     "/dev/ttyS0"
+#define UART1     "/dev/ttyS1"
 #define FBCONS    "/dev/fbcons"
 
 arm_pl011_context pl011_context;
+ns16550_context aux_context;
 
 rpi_fb_context fb_context;
 
-static void output_char_serial(char c)
+static void output_char_pl011(char c)
 {
   arm_pl011_write_polled(&pl011_context.base, c);
 }
 
+static void output_char_aux(char c)
+{
+  ns16550_polled_putchar(&aux_context.base, c);
+}
+
 void output_char_fb(char c)
 {
   fbcons_write_polled(&fb_context.base, c);
 }
 
+static uint8_t raspberrypi_get_reg(uintptr_t port, uint8_t index)
+{
+  volatile uint32_t *val = (volatile uint32_t *)port + index;
+  return (uint8_t) *val;
+}
+
+static void raspberrypi_set_reg(uintptr_t port, uint8_t index, uint8_t val)
+{
+  volatile uint32_t *reg = (volatile uint32_t *)port + index;
+  *reg = val;
+}
+
 static void init_ctx_arm_pl011(
   const void *fdt,
   int node
 )
 {
   arm_pl011_context *ctx = &pl011_context;
-  rtems_termios_device_context_initialize(&ctx->base, "UART");
+  rtems_termios_device_context_initialize(&ctx->base, "UART 0");
   ctx->regs = raspberrypi_get_reg_of_node(fdt, node);
 }
 
+static uint32_t calculate_baud_divisor(
+  ns16550_context *ctx,
+  uint32_t baud
+)
+{
+  uint32_t baudDivisor = (ctx->clock / (8 * baud)) - 1;
+  return baudDivisor;
+}
+
+static void init_ctx_aux(
+  const void *fdt,
+  int node
+)
+{
+  const char *status;
+  int len;
+  ns16550_context *ctx = &aux_context;
+  rtems_termios_device_context_initialize(&ctx->base, "UART 1");
+
+  status = fdt_getprop(fdt, node, "status", &len);
+  if (status == NULL){
+    return ;
+  }
+
+  if ( strcmp(status, "disabled") == 0 ) {
+    return ;
+  }
+
+  ctx->port = (uintptr_t) raspberrypi_get_reg_of_node(fdt, node);
+  ctx->initial_baud = AUX_DEFAULT_BAUD;
+  ctx->clock = BCM2835_CLOCK_FREQ;
+  ctx->calculate_baud_divisor = calculate_baud_divisor;
+  ctx->get_reg = raspberrypi_get_reg;
+  ctx->set_reg = raspberrypi_set_reg;
+
+  rtems_gpio_bsp_select_specific_io(0, 14, RPI_ALT_FUNC_5, NULL);
+  rtems_gpio_bsp_select_specific_io(0, 15, RPI_ALT_FUNC_5, NULL);
+  rtems_gpio_bsp_set_resistor_mode(0, 14, NO_PULL_RESISTOR);
+  rtems_gpio_bsp_set_resistor_mode(0, 15, NO_PULL_RESISTOR);
+
+  BCM2835_REG(AUX_ENABLES) |= 0x1;
+  ns16550_probe(&ctx->base);
+}
+
 static void register_fb( void )
 {
   if (fbcons_probe(&fb_context.base) == true) {
@@ -87,16 +156,27 @@ static void console_select( void )
         link(FBCONS, CONSOLE_DEVICE_NAME);
         return ;
       }
+    } else if ( strncmp( opt, UART1, sizeof(UART1) - 1 ) == 0) {
+      BSP_output_char = output_char_aux;
+      link(UART1, CONSOLE_DEVICE_NAME);
+    } else if ( strncmp( opt, UART0, sizeof(UART0) - 1 ) == 0) {
+      BSP_output_char = output_char_pl011;
+      link(UART0, CONSOLE_DEVICE_NAME);
     }
   }
-  BSP_output_char = output_char_serial;
-  link(UART0, CONSOLE_DEVICE_NAME);
+  /**
+   * If no command line option was given, default to AUX uart.
+   */
+  BSP_output_char = output_char_aux;
+  link(UART1, CONSOLE_DEVICE_NAME);
 }
 
 static void uart_probe(void)
 {
   static bool initialized = false;
   const void *fdt;
+  const char *console;
+  int len;
   int node;
 
   if ( initialized ) {
@@ -104,17 +184,29 @@ static void uart_probe(void)
   }
 
   fdt = bsp_fdt_get();
-  node = fdt_node_offset_by_compatible(fdt, -1, "brcm,bcm2835-pl011");
 
+  node = fdt_node_offset_by_compatible(fdt, -1, "brcm,bcm2835-pl011");
   init_ctx_arm_pl011(fdt, node);
 
+  node = fdt_node_offset_by_compatible(fdt, -1, "brcm,bcm2835-aux-uart");
+  init_ctx_aux(fdt, node);
+
+  node = fdt_path_offset(fdt, "/aliases");
+  console = fdt_getprop(fdt, node, "serial0", &len);
+
+  if (strcmp(console, "/soc/serial at 7e215040") == 0) {
+    BSP_output_char = output_char_aux;
+  }else {
+    BSP_output_char = output_char_pl011;
+  }
+
   initialized = true;
 }
 
 static void output_char(char c)
 {
   uart_probe();
-  output_char_serial(c);
+  (*BSP_output_char)(c);
 }
 
 rtems_status_code console_initialize(
@@ -133,6 +225,13 @@ rtems_status_code console_initialize(
     &pl011_context.base
   );
 
+  rtems_termios_device_install(
+    UART1,
+    &ns16550_handler_polled,
+    NULL,
+    &aux_context.base
+  );
+
   register_fb();
 
   console_select();
diff --git a/bsps/arm/raspberrypi/include/bsp/usart.h b/bsps/arm/raspberrypi/include/bsp/usart.h
index abbf53626c9..c73cebc86bd 100644
--- a/bsps/arm/raspberrypi/include/bsp/usart.h
+++ b/bsps/arm/raspberrypi/include/bsp/usart.h
@@ -33,6 +33,7 @@ extern "C" {
 #endif /* __cplusplus */
 
 #define PL011_DEFAULT_BAUD 115000
+#define AUX_DEFAULT_BAUD   115200
 #define BCM2835_PL011_BASE (RPI_PERIPHERAL_BASE + 0x201000)
 
 #ifdef __cplusplus
-- 
2.17.1