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 #define MAX_SERIAL_PORTS		4
39 
40 /*
41  * RCC USART specific definitions
42  */
43 #define RCC_ENR_USART1EN		(1 << 4)
44 #define RCC_ENR_USART2EN		(1 << 17)
45 #define RCC_ENR_USART3EN		(1 << 18)
46 #define RCC_ENR_USART6EN		(1 <<  5)
47 
48 /* Array used to figure out which RCC bit needs to be set */
49 static const unsigned long usart_port_rcc_pairs[MAX_SERIAL_PORTS][2] = {
50 	{ STM32_USART1_BASE, RCC_ENR_USART1EN },
51 	{ STM32_USART2_BASE, RCC_ENR_USART2EN },
52 	{ STM32_USART3_BASE, RCC_ENR_USART3EN },
53 	{ STM32_USART6_BASE, RCC_ENR_USART6EN }
54 };
55 
56 static int stm32_serial_setbrg(struct udevice *dev, int baudrate)
57 {
58 	struct stm32_serial_platdata *plat = dev->platdata;
59 	struct stm32_usart *const usart = plat->base;
60 	u32  clock, int_div, frac_div, tmp;
61 
62 	if (((u32)usart & STM32_BUS_MASK) == STM32_APB1PERIPH_BASE)
63 		clock = clock_get(CLOCK_APB1);
64 	else if (((u32)usart & STM32_BUS_MASK) == STM32_APB2PERIPH_BASE)
65 		clock = clock_get(CLOCK_APB2);
66 	else
67 		return -EINVAL;
68 
69 	int_div = (25 * clock) / (4 * baudrate);
70 	tmp = ((int_div / 100) << USART_BRR_M_SHIFT) & USART_BRR_M_MASK;
71 	frac_div = int_div - (100 * (tmp >> USART_BRR_M_SHIFT));
72 	tmp |= (((frac_div * 16) + 50) / 100) & USART_BRR_F_MASK;
73 	writel(tmp, &usart->brr);
74 
75 	return 0;
76 }
77 
78 static int stm32_serial_getc(struct udevice *dev)
79 {
80 	struct stm32_serial_platdata *plat = dev->platdata;
81 	struct stm32_usart *const usart = plat->base;
82 
83 	if ((readl(&usart->sr) & USART_SR_FLAG_RXNE) == 0)
84 		return -EAGAIN;
85 
86 	return readl(&usart->dr);
87 }
88 
89 static int stm32_serial_putc(struct udevice *dev, const char c)
90 {
91 	struct stm32_serial_platdata *plat = dev->platdata;
92 	struct stm32_usart *const usart = plat->base;
93 
94 	if ((readl(&usart->sr) & USART_SR_FLAG_TXE) == 0)
95 		return -EAGAIN;
96 
97 	writel(c, &usart->dr);
98 
99 	return 0;
100 }
101 
102 static int stm32_serial_pending(struct udevice *dev, bool input)
103 {
104 	struct stm32_serial_platdata *plat = dev->platdata;
105 	struct stm32_usart *const usart = plat->base;
106 
107 	if (input)
108 		return readl(&usart->sr) & USART_SR_FLAG_RXNE ? 1 : 0;
109 	else
110 		return readl(&usart->sr) & USART_SR_FLAG_TXE ? 0 : 1;
111 }
112 
113 static int stm32_serial_probe(struct udevice *dev)
114 {
115 	struct stm32_serial_platdata *plat = dev->platdata;
116 	struct stm32_usart *const usart = plat->base;
117 	int usart_port = -1;
118 	int i;
119 
120 	for (i = 0; i < MAX_SERIAL_PORTS; i++) {
121 		if ((u32)usart == usart_port_rcc_pairs[i][0]) {
122 			usart_port = i;
123 			break;
124 		}
125 	}
126 
127 	if (usart_port == -1)
128 		return -EINVAL;
129 
130 	if (((u32)usart & STM32_BUS_MASK) == STM32_APB1PERIPH_BASE)
131 		setbits_le32(&STM32_RCC->apb1enr,
132 			     usart_port_rcc_pairs[usart_port][1]);
133 	else if (((u32)usart & STM32_BUS_MASK) == STM32_APB2PERIPH_BASE)
134 		setbits_le32(&STM32_RCC->apb2enr,
135 			     usart_port_rcc_pairs[usart_port][1]);
136 	else
137 		return -EINVAL;
138 
139 	setbits_le32(&usart->cr1, USART_CR1_RE | USART_CR1_TE | USART_CR1_UE);
140 
141 	return 0;
142 }
143 
144 static const struct dm_serial_ops stm32_serial_ops = {
145 	.putc = stm32_serial_putc,
146 	.pending = stm32_serial_pending,
147 	.getc = stm32_serial_getc,
148 	.setbrg = stm32_serial_setbrg,
149 };
150 
151 U_BOOT_DRIVER(serial_stm32) = {
152 	.name = "serial_stm32",
153 	.id = UCLASS_SERIAL,
154 	.ops = &stm32_serial_ops,
155 	.probe = stm32_serial_probe,
156 	.flags = DM_FLAG_PRE_RELOC,
157 };
158