3 * Kamil Lulko, <rev13@wp.pl>
5 * SPDX-License-Identifier: GPL-2.0+
11 #include <asm/arch/stm32.h>
13 #define STM32_USART1_BASE (STM32_APB2PERIPH_BASE + 0x1000)
14 #define RCC_APB2ENR_USART1EN (1 << 4)
16 #define USART_BASE STM32_USART1_BASE
17 #define RCC_USART_ENABLE RCC_APB2ENR_USART1EN
29 #define USART_CR1_RE (1 << 2)
30 #define USART_CR1_TE (1 << 3)
31 #define USART_CR1_UE (1 << 13)
33 #define USART_SR_FLAG_RXNE (1 << 5)
34 #define USART_SR_FLAG_TXE (1 << 7)
36 #define USART_BRR_F_MASK 0xF
37 #define USART_BRR_M_SHIFT 4
38 #define USART_BRR_M_MASK 0xFFF0
40 DECLARE_GLOBAL_DATA_PTR;
42 static void stm32_serial_setbrg(void)
47 static int stm32_serial_init(void)
49 struct stm32_serial *usart = (struct stm32_serial *)USART_BASE;
50 u32 clock, int_div, frac_div, tmp;
52 if ((USART_BASE & STM32_BUS_MASK) == STM32_APB1PERIPH_BASE) {
53 setbits_le32(&STM32_RCC->apb1enr, RCC_USART_ENABLE);
54 clock = clock_get(CLOCK_APB1);
55 } else if ((USART_BASE & STM32_BUS_MASK) == STM32_APB2PERIPH_BASE) {
56 setbits_le32(&STM32_RCC->apb2enr, RCC_USART_ENABLE);
57 clock = clock_get(CLOCK_APB2);
62 int_div = (25 * clock) / (4 * gd->baudrate);
63 tmp = ((int_div / 100) << USART_BRR_M_SHIFT) & USART_BRR_M_MASK;
64 frac_div = int_div - (100 * (tmp >> USART_BRR_M_SHIFT));
65 tmp |= (((frac_div * 16) + 50) / 100) & USART_BRR_F_MASK;
67 writel(tmp, &usart->brr);
68 setbits_le32(&usart->cr1, USART_CR1_RE | USART_CR1_TE | USART_CR1_UE);
73 static int stm32_serial_getc(void)
75 struct stm32_serial *usart = (struct stm32_serial *)USART_BASE;
76 while ((readl(&usart->sr) & USART_SR_FLAG_RXNE) == 0)
78 return readl(&usart->dr);
81 static void stm32_serial_putc(const char c)
83 struct stm32_serial *usart = (struct stm32_serial *)USART_BASE;
84 while ((readl(&usart->sr) & USART_SR_FLAG_TXE) == 0)
86 writel(c, &usart->dr);
89 static int stm32_serial_tstc(void)
91 struct stm32_serial *usart = (struct stm32_serial *)USART_BASE;
94 ret = readl(&usart->sr) & USART_SR_FLAG_RXNE;
98 static struct serial_device stm32_serial_drv = {
99 .name = "stm32_serial",
100 .start = stm32_serial_init,
102 .setbrg = stm32_serial_setbrg,
103 .putc = stm32_serial_putc,
104 .puts = default_serial_puts,
105 .getc = stm32_serial_getc,
106 .tstc = stm32_serial_tstc,
109 void stm32_serial_initialize(void)
111 serial_register(&stm32_serial_drv);
114 __weak struct serial_device *default_serial_console(void)
116 return &stm32_serial_drv;