xref: /openbmc/u-boot/drivers/serial/serial_arc.c (revision 748ad078)
1 /*
2  * Copyright (C) 2013 Synopsys, Inc. (www.synopsys.com)
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License version 2 as
6  * published by the Free Software Foundation.
7  *
8  */
9 
10 #include <common.h>
11 #include <dm.h>
12 #include <serial.h>
13 
14 DECLARE_GLOBAL_DATA_PTR;
15 
16 struct arc_serial_regs {
17 	unsigned int id0;
18 	unsigned int id1;
19 	unsigned int id2;
20 	unsigned int id3;
21 	unsigned int data;
22 	unsigned int status;
23 	unsigned int baudl;
24 	unsigned int baudh;
25 };
26 
27 
28 struct arc_serial_platdata {
29 	struct arc_serial_regs *reg;
30 	unsigned int uartclk;
31 };
32 
33 /* Bit definitions of STATUS register */
34 #define UART_RXEMPTY		(1 << 5)
35 #define UART_OVERFLOW_ERR	(1 << 1)
36 #define UART_TXEMPTY		(1 << 7)
37 
arc_serial_setbrg(struct udevice * dev,int baudrate)38 static int arc_serial_setbrg(struct udevice *dev, int baudrate)
39 {
40 	struct arc_serial_platdata *plat = dev->platdata;
41 	struct arc_serial_regs *const regs = plat->reg;
42 	int arc_console_baud = gd->cpu_clk / (baudrate * 4) - 1;
43 
44 	writeb(arc_console_baud & 0xff, &regs->baudl);
45 	writeb((arc_console_baud & 0xff00) >> 8, &regs->baudh);
46 
47 	return 0;
48 }
49 
arc_serial_putc(struct udevice * dev,const char c)50 static int arc_serial_putc(struct udevice *dev, const char c)
51 {
52 	struct arc_serial_platdata *plat = dev->platdata;
53 	struct arc_serial_regs *const regs = plat->reg;
54 
55 	while (!(readb(&regs->status) & UART_TXEMPTY))
56 		;
57 
58 	writeb(c, &regs->data);
59 
60 	return 0;
61 }
62 
arc_serial_tstc(struct arc_serial_regs * const regs)63 static int arc_serial_tstc(struct arc_serial_regs *const regs)
64 {
65 	return !(readb(&regs->status) & UART_RXEMPTY);
66 }
67 
arc_serial_pending(struct udevice * dev,bool input)68 static int arc_serial_pending(struct udevice *dev, bool input)
69 {
70 	struct arc_serial_platdata *plat = dev->platdata;
71 	struct arc_serial_regs *const regs = plat->reg;
72 	uint32_t status = readb(&regs->status);
73 
74 	if (input)
75 		return status & UART_RXEMPTY ? 0 : 1;
76 	else
77 		return status & UART_TXEMPTY ? 0 : 1;
78 }
79 
arc_serial_getc(struct udevice * dev)80 static int arc_serial_getc(struct udevice *dev)
81 {
82 	struct arc_serial_platdata *plat = dev->platdata;
83 	struct arc_serial_regs *const regs = plat->reg;
84 
85 	while (!arc_serial_tstc(regs))
86 		;
87 
88 	/* Check for overflow errors */
89 	if (readb(&regs->status) & UART_OVERFLOW_ERR)
90 		return 0;
91 
92 	return readb(&regs->data) & 0xFF;
93 }
94 
arc_serial_probe(struct udevice * dev)95 static int arc_serial_probe(struct udevice *dev)
96 {
97 	return 0;
98 }
99 
100 static const struct dm_serial_ops arc_serial_ops = {
101 	.putc = arc_serial_putc,
102 	.pending = arc_serial_pending,
103 	.getc = arc_serial_getc,
104 	.setbrg = arc_serial_setbrg,
105 };
106 
107 static const struct udevice_id arc_serial_ids[] = {
108 	{ .compatible = "snps,arc-uart" },
109 	{ }
110 };
111 
arc_serial_ofdata_to_platdata(struct udevice * dev)112 static int arc_serial_ofdata_to_platdata(struct udevice *dev)
113 {
114 	struct arc_serial_platdata *plat = dev_get_platdata(dev);
115 	DECLARE_GLOBAL_DATA_PTR;
116 
117 	plat->reg = (struct arc_serial_regs *)devfdt_get_addr(dev);
118 	plat->uartclk = fdtdec_get_int(gd->fdt_blob, dev_of_offset(dev),
119 				       "clock-frequency", 0);
120 
121 	return 0;
122 }
123 
124 U_BOOT_DRIVER(serial_arc) = {
125 	.name	= "serial_arc",
126 	.id	= UCLASS_SERIAL,
127 	.of_match = arc_serial_ids,
128 	.ofdata_to_platdata = arc_serial_ofdata_to_platdata,
129 	.platdata_auto_alloc_size = sizeof(struct arc_serial_platdata),
130 	.probe = arc_serial_probe,
131 	.ops	= &arc_serial_ops,
132 };
133 
134 #ifdef CONFIG_DEBUG_ARC_SERIAL
135 #include <debug_uart.h>
136 
_debug_uart_init(void)137 static inline void _debug_uart_init(void)
138 {
139 	struct arc_serial_regs *regs = (struct arc_serial_regs *)CONFIG_DEBUG_UART_BASE;
140 	int arc_console_baud = CONFIG_DEBUG_UART_CLOCK / (CONFIG_BAUDRATE * 4) - 1;
141 
142 	writeb(arc_console_baud & 0xff, &regs->baudl);
143 	writeb((arc_console_baud & 0xff00) >> 8, &regs->baudh);
144 }
145 
_debug_uart_putc(int c)146 static inline void _debug_uart_putc(int c)
147 {
148 	struct arc_serial_regs *regs = (struct arc_serial_regs *)CONFIG_DEBUG_UART_BASE;
149 
150 	while (!(readb(&regs->status) & UART_TXEMPTY))
151 		;
152 
153 	writeb(c, &regs->data);
154 }
155 
156 DEBUG_UART_FUNCS
157 
158 #endif
159