1 /*
2  * Copyright 2013 Freescale Semiconductor, Inc.
3  *
4  * SPDX-License-Identifier:	GPL-2.0+
5  */
6 
7 #include <common.h>
8 #include <watchdog.h>
9 #include <asm/io.h>
10 #include <serial.h>
11 #include <linux/compiler.h>
12 #include <asm/arch/imx-regs.h>
13 #include <asm/arch/clock.h>
14 
15 #define US1_TDRE        (1 << 7)
16 #define US1_RDRF        (1 << 5)
17 #define UC2_TE          (1 << 3)
18 #define UC2_RE          (1 << 2)
19 
20 DECLARE_GLOBAL_DATA_PTR;
21 
22 struct lpuart_fsl *base = (struct lpuart_fsl *)LPUART_BASE;
23 
24 static void lpuart_serial_setbrg(void)
25 {
26 	u32 clk = mxc_get_clock(MXC_UART_CLK);
27 	u16 sbr;
28 
29 	if (!gd->baudrate)
30 		gd->baudrate = CONFIG_BAUDRATE;
31 
32 	sbr = (u16)(clk / (16 * gd->baudrate));
33 	/* place adjustment later - n/32 BRFA */
34 
35 	__raw_writeb(sbr >> 8, &base->ubdh);
36 	__raw_writeb(sbr & 0xff, &base->ubdl);
37 }
38 
39 static int lpuart_serial_getc(void)
40 {
41 	u8 status;
42 
43 	while (!(__raw_readb(&base->us1) & US1_RDRF))
44 		WATCHDOG_RESET();
45 
46 	status = __raw_readb(&base->us1);
47 	status |= US1_RDRF;
48 	__raw_writeb(status, &base->us1);
49 
50 	return __raw_readb(&base->ud);
51 }
52 
53 static void lpuart_serial_putc(const char c)
54 {
55 	if (c == '\n')
56 		serial_putc('\r');
57 
58 	while (!(__raw_readb(&base->us1) & US1_TDRE))
59 		WATCHDOG_RESET();
60 
61 	__raw_writeb(c, &base->ud);
62 }
63 
64 /*
65  * Test whether a character is in the RX buffer
66  */
67 static int lpuart_serial_tstc(void)
68 {
69 	if (__raw_readb(&base->urcfifo) == 0)
70 		return 0;
71 
72 	return 1;
73 }
74 
75 /*
76  * Initialise the serial port with the given baudrate. The settings
77  * are always 8 data bits, no parity, 1 stop bit, no start bits.
78  */
79 static int lpuart_serial_init(void)
80 {
81 	u8 ctrl;
82 
83 	ctrl = __raw_readb(&base->uc2);
84 	ctrl &= ~UC2_RE;
85 	ctrl &= ~UC2_TE;
86 	__raw_writeb(ctrl, &base->uc2);
87 
88 	__raw_writeb(0, &base->umodem);
89 	__raw_writeb(0, &base->uc1);
90 
91 	/* provide data bits, parity, stop bit, etc */
92 
93 	serial_setbrg();
94 
95 	__raw_writeb(UC2_RE | UC2_TE, &base->uc2);
96 
97 	return 0;
98 }
99 
100 static struct serial_device lpuart_serial_drv = {
101 	.name = "lpuart_serial",
102 	.start = lpuart_serial_init,
103 	.stop = NULL,
104 	.setbrg = lpuart_serial_setbrg,
105 	.putc = lpuart_serial_putc,
106 	.puts = default_serial_puts,
107 	.getc = lpuart_serial_getc,
108 	.tstc = lpuart_serial_tstc,
109 };
110 
111 void lpuart_serial_initialize(void)
112 {
113 	serial_register(&lpuart_serial_drv);
114 }
115 
116 __weak struct serial_device *default_serial_console(void)
117 {
118 	return &lpuart_serial_drv;
119 }
120