drivers/serial/serial_stm32.c

   1 /*
   2  * (C) Copyright 2015
   3  * Kamil Lulko, <kamil.lulko@gmail.com>
   4  *
   5  * SPDX-License-Identifier:     GPL-2.0+
   6  */
   7
   8 #include <common.h>
   9 #include <dm.h>
  10 #include <asm/io.h>
  11 #include <serial.h>
  12 #include <asm/arch/stm32.h>
  13 #include <dm/platform_data/serial_stm32.h>
  14
  15 struct stm32_usart {
  16         u32 sr;
  17         u32 dr;
  18         u32 brr;
  19         u32 cr1;
  20         u32 cr2;
  21         u32 cr3;
  22         u32 gtpr;
  23 };
  24
  25 #define USART_CR1_RE                    (1 << 2)
  26 #define USART_CR1_TE                    (1 << 3)
  27 #define USART_CR1_UE                    (1 << 13)
  28
  29 #define USART_SR_FLAG_RXNE      (1 << 5)
  30 #define USART_SR_FLAG_TXE               (1 << 7)
  31
  32 #define USART_BRR_F_MASK                0xF
  33 #define USART_BRR_M_SHIFT       4
  34 #define USART_BRR_M_MASK        0xFFF0
  35
  36 DECLARE_GLOBAL_DATA_PTR;
  37
  38 static int stm32_serial_setbrg(struct udevice *dev, int baudrate)
  39 {
  40         struct stm32_serial_platdata *plat = dev->platdata;
  41         struct stm32_usart *const usart = plat->base;
  42         u32  clock, int_div, frac_div, tmp;
  43
  44         if (((u32)usart & STM32_BUS_MASK) == STM32_APB1PERIPH_BASE)
  45                 clock = clock_get(CLOCK_APB1);
  46         else if (((u32)usart & STM32_BUS_MASK) == STM32_APB2PERIPH_BASE)
  47                 clock = clock_get(CLOCK_APB2);
  48         else
  49                 return -EINVAL;
  50
  51         int_div = (25 * clock) / (4 * baudrate);
  52         tmp = ((int_div / 100) << USART_BRR_M_SHIFT) & USART_BRR_M_MASK;
  53         frac_div = int_div - (100 * (tmp >> USART_BRR_M_SHIFT));
  54         tmp |= (((frac_div * 16) + 50) / 100) & USART_BRR_F_MASK;
  55         writel(tmp, &usart->brr);
  56
  57         return 0;
  58 }
  59
  60 static int stm32_serial_getc(struct udevice *dev)
  61 {
  62         struct stm32_serial_platdata *plat = dev->platdata;
  63         struct stm32_usart *const usart = plat->base;
  64
  65         if ((readl(&usart->sr) & USART_SR_FLAG_RXNE) == 0)
  66                 return -EAGAIN;
  67
  68         return readl(&usart->dr);
  69 }
  70
  71 static int stm32_serial_putc(struct udevice *dev, const char c)
  72 {
  73         struct stm32_serial_platdata *plat = dev->platdata;
  74         struct stm32_usart *const usart = plat->base;
  75
  76         if ((readl(&usart->sr) & USART_SR_FLAG_TXE) == 0)
  77                 return -EAGAIN;
  78
  79         writel(c, &usart->dr);
  80
  81         return 0;
  82 }
  83
  84 static int stm32_serial_pending(struct udevice *dev, bool input)
  85 {
  86         struct stm32_serial_platdata *plat = dev->platdata;
  87         struct stm32_usart *const usart = plat->base;
  88
  89         if (input)
  90                 return readl(&usart->sr) & USART_SR_FLAG_RXNE ? 1 : 0;
  91         else
  92                 return readl(&usart->sr) & USART_SR_FLAG_TXE ? 0 : 1;
  93 }
  94
  95 static int stm32_serial_probe(struct udevice *dev)
  96 {
  97         struct stm32_serial_platdata *plat = dev->platdata;
  98         struct stm32_usart *const usart = plat->base;
  99         setbits_le32(&usart->cr1, USART_CR1_RE | USART_CR1_TE | USART_CR1_UE);
 100
 101         return 0;
 102 }
 103
 104 static const struct dm_serial_ops stm32_serial_ops = {
 105         .putc = stm32_serial_putc,
 106         .pending = stm32_serial_pending,
 107         .getc = stm32_serial_getc,
 108         .setbrg = stm32_serial_setbrg,
 109 };
 110
 111 U_BOOT_DRIVER(serial_stm32) = {
 112         .name = "serial_stm32",
 113         .id = UCLASS_SERIAL,
 114         .ops = &stm32_serial_ops,
 115         .probe = stm32_serial_probe,
 116         .flags = DM_FLAG_PRE_RELOC,
 117 };