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 };
118