From 31ad67abd71bd044ab80a66534f3995fd10f3edc Mon Sep 17 00:00:00 2001
From: Michael LeMay <lemaymd@gmail.com>
Date: Wed, 3 Aug 2016 07:58:51 -0700
Subject: [PATCH] x86: Support configurable UART baud rate

This patch extends the Intel Quark X1000 SoC UART initialization API to
accept a numeric baud rate specification.
---
 cpu/x86/drivers/quarkX1000/uart.c | 13 ++++++++-----
 cpu/x86/drivers/quarkX1000/uart.h |  2 +-
 platform/galileo/contiki-main.c   |  6 ++++--
 3 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/cpu/x86/drivers/quarkX1000/uart.c b/cpu/x86/drivers/quarkX1000/uart.c
index 341e31cf7..c78a04ca1 100644
--- a/cpu/x86/drivers/quarkX1000/uart.c
+++ b/cpu/x86/drivers/quarkX1000/uart.c
@@ -35,10 +35,10 @@
 PROT_DOMAINS_ALLOC(uart_16x50_driver_t, quarkX1000_uart0);
 PROT_DOMAINS_ALLOC(uart_16x50_driver_t, quarkX1000_uart1);
 
-/* Divisor setting for 115200 baud from section 18.2.2 of Intel Quark SoC
- * X1000 Datasheet.
+/* UART base frequency from section 18.2.2 of Intel Quark SoC X1000
+ * Datasheet.
  */
-#define QUARK_X1000_UART_DL_115200 24
+#define QUARK_X1000_UART_FBASE 44236800
 
 /*---------------------------------------------------------------------------*/
 /**
@@ -46,8 +46,9 @@ PROT_DOMAINS_ALLOC(uart_16x50_driver_t, quarkX1000_uart1);
  * \param dev Device to initialize.
  */
 void
-quarkX1000_uart_init(quarkX1000_uart_dev_t dev)
+quarkX1000_uart_init(quarkX1000_uart_dev_t dev, unsigned baud)
 {
+  uint16_t dl;
   pci_config_addr_t pci_addr;
   uart_16x50_driver_t ATTR_KERN_ADDR_SPACE *drv;
 
@@ -67,7 +68,9 @@ quarkX1000_uart_init(quarkX1000_uart_dev_t dev)
     drv = &quarkX1000_uart1;
     PROT_DOMAINS_INIT_ID(quarkX1000_uart1);
   }
-  uart_16x50_init(drv, pci_addr, QUARK_X1000_UART_DL_115200);
+  /* Divisor setting from section 18.2.2 of Intel Quark SoC X1000 Datasheet. */
+  dl = QUARK_X1000_UART_FBASE / (16 * baud);
+  uart_16x50_init(drv, pci_addr, dl);
 }
 /*---------------------------------------------------------------------------*/
 /**
diff --git a/cpu/x86/drivers/quarkX1000/uart.h b/cpu/x86/drivers/quarkX1000/uart.h
index 8b545d8cd..2eec5c103 100644
--- a/cpu/x86/drivers/quarkX1000/uart.h
+++ b/cpu/x86/drivers/quarkX1000/uart.h
@@ -38,7 +38,7 @@ typedef enum {
   QUARK_X1000_UART_1
 } quarkX1000_uart_dev_t;
 
-void quarkX1000_uart_init(quarkX1000_uart_dev_t dev);
+void quarkX1000_uart_init(quarkX1000_uart_dev_t dev, unsigned baud);
 void quarkX1000_uart_tx(quarkX1000_uart_dev_t dev, uint8_t c);
 
 #endif /* CPU_X86_DRIVERS_QUARKX1000_UART_H_ */
diff --git a/platform/galileo/contiki-main.c b/platform/galileo/contiki-main.c
index ccc1f519f..3ac787af7 100644
--- a/platform/galileo/contiki-main.c
+++ b/platform/galileo/contiki-main.c
@@ -86,8 +86,10 @@ main(void)
   quarkX1000_imr_conf();
 #endif
   irq_init();
-  /* Initialize UART connected to Galileo Gen2 FTDI header */
-  quarkX1000_uart_init(QUARK_X1000_UART_1);
+  /* Initialize UART connected to Galileo Gen1 3.5mm audio-style jack or
+   * Galileo Gen2 FTDI header
+   */
+  quarkX1000_uart_init(QUARK_X1000_UART_1, 115200);
   clock_init();
   rtimer_init();