stm32f4: Add serial driver

Signed-off-by: Kamil Lulko <rev13@wp.pl>
Reviewed-by: Tom Rini <trini@konsulko.com>

drivers/serial/Makefile

@@ -44,6 +44,7 @@ obj-$(CONFIG_TEGRA_SERIAL) += serial_tegra.o
 obj-$(CONFIG_UNIPHIER_SERIAL) += serial_uniphier.o
 obj-$(CONFIG_OMAP_SERIAL) += serial_omap.o
 obj-$(CONFIG_X86_SERIAL) += serial_x86.o
+obj-$(CONFIG_STM32_SERIAL) += serial_stm32.o
 
 ifndef CONFIG_SPL_BUILD
 obj-$(CONFIG_USB_TTY) += usbtty.o

drivers/serial/serial.c

@@ -154,6 +154,7 @@ serial_initfunc(sa1100_serial_initialize);
 serial_initfunc(sandbox_serial_initialize);
 serial_initfunc(sconsole_serial_initialize);
 serial_initfunc(sh_serial_initialize);
+serial_initfunc(stm32_serial_initialize);
 serial_initfunc(uartlite_serial_initialize);
 serial_initfunc(zynq_serial_initialize);
 
@@ -246,6 +247,7 @@ void serial_initialize(void)
 	sandbox_serial_initialize();
 	sconsole_serial_initialize();
 	sh_serial_initialize();
+	stm32_serial_initialize();
 	uartlite_serial_initialize();
 	zynq_serial_initialize();
 

drivers/serial/serial_stm32.c

+/*
+ * (C) Copyright 2015
+ * Kamil Lulko, <rev13@wp.pl>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <asm/io.h>
+#include <serial.h>
+#include <asm/arch/stm32.h>
+
+#define STM32_USART1_BASE	(STM32_APB2PERIPH_BASE + 0x1000)
+#define RCC_APB2ENR_USART1EN	(1 << 4)
+
+#define USART_BASE		STM32_USART1_BASE
+#define RCC_USART_ENABLE	RCC_APB2ENR_USART1EN
+
+struct stm32_serial {
+	u32 sr;
+	u32 dr;
+	u32 brr;
+	u32 cr1;
+	u32 cr2;
+	u32 cr3;
+	u32 gtpr;
+};
+
+#define USART_CR1_RE		(1 << 2)
+#define USART_CR1_TE		(1 << 3)
+#define USART_CR1_UE		(1 << 13)
+
+#define USART_SR_FLAG_RXNE	(1 << 5)
+#define USART_SR_FLAG_TXE	(1 << 7)
+
+#define USART_BRR_F_MASK	0xF
+#define USART_BRR_M_SHIFT	4
+#define USART_BRR_M_MASK	0xFFF0
+
+DECLARE_GLOBAL_DATA_PTR;
+
+static void stm32_serial_setbrg(void)
+{
+	serial_init();
+}
+
+static int stm32_serial_init(void)
+{
+	struct stm32_serial *usart = (struct stm32_serial *)USART_BASE;
+	u32 clock, int_div, frac_div, tmp;
+
+	if ((USART_BASE & STM32_BUS_MASK) == STM32_APB1PERIPH_BASE) {
+		setbits_le32(&STM32_RCC->apb1enr, RCC_USART_ENABLE);
+		clock = clock_get(CLOCK_APB1);
+	} else if ((USART_BASE & STM32_BUS_MASK) == STM32_APB2PERIPH_BASE) {
+		setbits_le32(&STM32_RCC->apb2enr, RCC_USART_ENABLE);
+		clock = clock_get(CLOCK_APB2);
+	} else {
+		return -1;
+	}
+
+	int_div = (25 * clock) / (4 * gd->baudrate);
+	tmp = ((int_div / 100) << USART_BRR_M_SHIFT) & USART_BRR_M_MASK;
+	frac_div = int_div - (100 * (tmp >> USART_BRR_M_SHIFT));
+	tmp |= (((frac_div * 16) + 50) / 100) & USART_BRR_F_MASK;
+
+	writel(tmp, &usart->brr);
+	setbits_le32(&usart->cr1, USART_CR1_RE | USART_CR1_TE | USART_CR1_UE);
+
+	return 0;
+}
+
+static int stm32_serial_getc(void)
+{
+	struct stm32_serial *usart = (struct stm32_serial *)USART_BASE;
+	while ((readl(&usart->sr) & USART_SR_FLAG_RXNE) == 0)
+		;
+	return readl(&usart->dr);
+}
+
+static void stm32_serial_putc(const char c)
+{
+	struct stm32_serial *usart = (struct stm32_serial *)USART_BASE;
+	while ((readl(&usart->sr) & USART_SR_FLAG_TXE) == 0)
+		;
+	writel(c, &usart->dr);
+}
+
+static int stm32_serial_tstc(void)
+{
+	struct stm32_serial *usart = (struct stm32_serial *)USART_BASE;
+	u8 ret;
+
+	ret = readl(&usart->sr) & USART_SR_FLAG_RXNE;
+	return ret;
+}
+
+static struct serial_device stm32_serial_drv = {
+	.name	= "stm32_serial",
+	.start	= stm32_serial_init,
+	.stop	= NULL,
+	.setbrg	= stm32_serial_setbrg,
+	.putc	= stm32_serial_putc,
+	.puts	= default_serial_puts,
+	.getc	= stm32_serial_getc,
+	.tstc	= stm32_serial_tstc,
+};
+
+void stm32_serial_initialize(void)
+{
+	serial_register(&stm32_serial_drv);
+}
+
+__weak struct serial_device *default_serial_console(void)
+{
+	return &stm32_serial_drv;
+}