serial_pic32.c
4.57 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
/*
* (c) 2015 Paul Thacker <paul.thacker@microchip.com>
*
* SPDX-License-Identifier: GPL-2.0+
*
*/
#include <common.h>
#include <clk.h>
#include <dm.h>
#include <serial.h>
#include <wait_bit.h>
#include <mach/pic32.h>
#include <dt-bindings/clock/microchip,clock.h>
DECLARE_GLOBAL_DATA_PTR;
/* UART Control Registers */
#define U_MOD 0x00
#define U_MODCLR (U_MOD + _CLR_OFFSET)
#define U_MODSET (U_MOD + _SET_OFFSET)
#define U_STA 0x10
#define U_STACLR (U_STA + _CLR_OFFSET)
#define U_STASET (U_STA + _SET_OFFSET)
#define U_TXR 0x20
#define U_RXR 0x30
#define U_BRG 0x40
/* U_MOD bits */
#define UART_ENABLE BIT(15)
/* U_STA bits */
#define UART_RX_ENABLE BIT(12)
#define UART_TX_BRK BIT(11)
#define UART_TX_ENABLE BIT(10)
#define UART_TX_FULL BIT(9)
#define UART_TX_EMPTY BIT(8)
#define UART_RX_OVER BIT(1)
#define UART_RX_DATA_AVAIL BIT(0)
struct pic32_uart_priv {
void __iomem *base;
ulong uartclk;
};
/*
* Initialize the serial port with the given baudrate.
* The settings are always 8 data bits, no parity, 1 stop bit, no start bits.
*/
static int pic32_serial_init(void __iomem *base, ulong clk, u32 baudrate)
{
u32 div = DIV_ROUND_CLOSEST(clk, baudrate * 16);
/* wait for TX FIFO to empty */
wait_for_bit_le32(base + U_STA, UART_TX_EMPTY,
true, CONFIG_SYS_HZ, false);
/* send break */
writel(UART_TX_BRK, base + U_STASET);
/* disable and clear mode */
writel(0, base + U_MOD);
writel(0, base + U_STA);
/* set baud rate generator */
writel(div - 1, base + U_BRG);
/* enable the UART for TX and RX */
writel(UART_TX_ENABLE | UART_RX_ENABLE, base + U_STASET);
/* enable the UART */
writel(UART_ENABLE, base + U_MODSET);
return 0;
}
/* Check whether any char pending in RX fifo */
static int pic32_uart_pending_input(void __iomem *base)
{
/* check if rx buffer overrun error has occurred */
if (readl(base + U_STA) & UART_RX_OVER) {
readl(base + U_RXR);
/* clear overrun error to keep receiving */
writel(UART_RX_OVER, base + U_STACLR);
}
/* In PIC32 there is no way to know number of outstanding
* chars in rx-fifo. Only it can be known whether there is any.
*/
return readl(base + U_STA) & UART_RX_DATA_AVAIL;
}
static int pic32_uart_pending(struct udevice *dev, bool input)
{
struct pic32_uart_priv *priv = dev_get_priv(dev);
if (input)
return pic32_uart_pending_input(priv->base);
return !(readl(priv->base + U_STA) & UART_TX_EMPTY);
}
static int pic32_uart_setbrg(struct udevice *dev, int baudrate)
{
struct pic32_uart_priv *priv = dev_get_priv(dev);
return pic32_serial_init(priv->base, priv->uartclk, baudrate);
}
static int pic32_uart_putc(struct udevice *dev, const char ch)
{
struct pic32_uart_priv *priv = dev_get_priv(dev);
/* Check if Tx FIFO is full */
if (readl(priv->base + U_STA) & UART_TX_FULL)
return -EAGAIN;
/* pump the char to tx buffer */
writel(ch, priv->base + U_TXR);
return 0;
}
static int pic32_uart_getc(struct udevice *dev)
{
struct pic32_uart_priv *priv = dev_get_priv(dev);
/* return error if RX fifo is empty */
if (!pic32_uart_pending_input(priv->base))
return -EAGAIN;
/* read the character from rx buffer */
return readl(priv->base + U_RXR) & 0xff;
}
static int pic32_uart_probe(struct udevice *dev)
{
struct pic32_uart_priv *priv = dev_get_priv(dev);
struct clk clk;
fdt_addr_t addr;
fdt_size_t size;
int ret;
/* get address */
addr = fdtdec_get_addr_size(gd->fdt_blob, dev_of_offset(dev), "reg",
&size);
if (addr == FDT_ADDR_T_NONE)
return -EINVAL;
priv->base = ioremap(addr, size);
/* get clock rate */
ret = clk_get_by_index(dev, 0, &clk);
if (ret < 0)
return ret;
priv->uartclk = clk_get_rate(&clk);
clk_free(&clk);
/* initialize serial */
return pic32_serial_init(priv->base, priv->uartclk, CONFIG_BAUDRATE);
}
static const struct dm_serial_ops pic32_uart_ops = {
.putc = pic32_uart_putc,
.pending = pic32_uart_pending,
.getc = pic32_uart_getc,
.setbrg = pic32_uart_setbrg,
};
static const struct udevice_id pic32_uart_ids[] = {
{ .compatible = "microchip,pic32mzda-uart" },
{}
};
U_BOOT_DRIVER(pic32_serial) = {
.name = "pic32-uart",
.id = UCLASS_SERIAL,
.of_match = pic32_uart_ids,
.probe = pic32_uart_probe,
.ops = &pic32_uart_ops,
.flags = DM_FLAG_PRE_RELOC,
.priv_auto_alloc_size = sizeof(struct pic32_uart_priv),
};
#ifdef CONFIG_DEBUG_UART_PIC32
#include <debug_uart.h>
static inline void _debug_uart_init(void)
{
void __iomem *base = (void __iomem *)CONFIG_DEBUG_UART_BASE;
pic32_serial_init(base, CONFIG_DEBUG_UART_CLOCK, CONFIG_BAUDRATE);
}
static inline void _debug_uart_putc(int ch)
{
writel(ch, CONFIG_DEBUG_UART_BASE + U_TXR);
}
DEBUG_UART_FUNCS
#endif