1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * Copyright (C) 2012 Michal Simek <monstr@monstr.eu>
4 * Copyright (C) 2011-2012 Xilinx, Inc. All rights reserved.
5 */
6
7 #include <clk.h>
8 #include <common.h>
9 #include <debug_uart.h>
10 #include <dm.h>
11 #include <errno.h>
12 #include <fdtdec.h>
13 #include <watchdog.h>
14 #include <asm/io.h>
15 #include <linux/compiler.h>
16 #include <serial.h>
17
18 DECLARE_GLOBAL_DATA_PTR;
19
20 #define ZYNQ_UART_SR_TXACTIVE BIT(11) /* TX active */
21 #define ZYNQ_UART_SR_TXFULL BIT(4) /* TX FIFO full */
22 #define ZYNQ_UART_SR_RXEMPTY BIT(1) /* RX FIFO empty */
23
24 #define ZYNQ_UART_CR_TX_EN BIT(4) /* TX enabled */
25 #define ZYNQ_UART_CR_RX_EN BIT(2) /* RX enabled */
26 #define ZYNQ_UART_CR_TXRST BIT(1) /* TX logic reset */
27 #define ZYNQ_UART_CR_RXRST BIT(0) /* RX logic reset */
28
29 #define ZYNQ_UART_MR_PARITY_NONE 0x00000020 /* No parity mode */
30
31 struct uart_zynq {
32 u32 control; /* 0x0 - Control Register [8:0] */
33 u32 mode; /* 0x4 - Mode Register [10:0] */
34 u32 reserved1[4];
35 u32 baud_rate_gen; /* 0x18 - Baud Rate Generator [15:0] */
36 u32 reserved2[4];
37 u32 channel_sts; /* 0x2c - Channel Status [11:0] */
38 u32 tx_rx_fifo; /* 0x30 - FIFO [15:0] or [7:0] */
39 u32 baud_rate_divider; /* 0x34 - Baud Rate Divider [7:0] */
40 };
41
42 struct zynq_uart_priv {
43 struct uart_zynq *regs;
44 };
45
46 /* Set up the baud rate in gd struct */
_uart_zynq_serial_setbrg(struct uart_zynq * regs,unsigned long clock,unsigned long baud)47 static void _uart_zynq_serial_setbrg(struct uart_zynq *regs,
48 unsigned long clock, unsigned long baud)
49 {
50 /* Calculation results. */
51 unsigned int calc_bauderror, bdiv, bgen;
52 unsigned long calc_baud = 0;
53
54 /* Covering case where input clock is so slow */
55 if (clock < 1000000 && baud > 4800)
56 baud = 4800;
57
58 /* master clock
59 * Baud rate = ------------------
60 * bgen * (bdiv + 1)
61 *
62 * Find acceptable values for baud generation.
63 */
64 for (bdiv = 4; bdiv < 255; bdiv++) {
65 bgen = clock / (baud * (bdiv + 1));
66 if (bgen < 2 || bgen > 65535)
67 continue;
68
69 calc_baud = clock / (bgen * (bdiv + 1));
70
71 /*
72 * Use first calculated baudrate with
73 * an acceptable (<3%) error
74 */
75 if (baud > calc_baud)
76 calc_bauderror = baud - calc_baud;
77 else
78 calc_bauderror = calc_baud - baud;
79 if (((calc_bauderror * 100) / baud) < 3)
80 break;
81 }
82
83 writel(bdiv, ®s->baud_rate_divider);
84 writel(bgen, ®s->baud_rate_gen);
85 }
86
87 /* Initialize the UART, with...some settings. */
_uart_zynq_serial_init(struct uart_zynq * regs)88 static void _uart_zynq_serial_init(struct uart_zynq *regs)
89 {
90 /* RX/TX enabled & reset */
91 writel(ZYNQ_UART_CR_TX_EN | ZYNQ_UART_CR_RX_EN | ZYNQ_UART_CR_TXRST | \
92 ZYNQ_UART_CR_RXRST, ®s->control);
93 writel(ZYNQ_UART_MR_PARITY_NONE, ®s->mode); /* 8 bit, no parity */
94 }
95
_uart_zynq_serial_putc(struct uart_zynq * regs,const char c)96 static int _uart_zynq_serial_putc(struct uart_zynq *regs, const char c)
97 {
98 if (readl(®s->channel_sts) & ZYNQ_UART_SR_TXFULL)
99 return -EAGAIN;
100
101 writel(c, ®s->tx_rx_fifo);
102
103 return 0;
104 }
105
zynq_serial_setbrg(struct udevice * dev,int baudrate)106 static int zynq_serial_setbrg(struct udevice *dev, int baudrate)
107 {
108 struct zynq_uart_priv *priv = dev_get_priv(dev);
109 unsigned long clock;
110
111 int ret;
112 struct clk clk;
113
114 ret = clk_get_by_index(dev, 0, &clk);
115 if (ret < 0) {
116 dev_err(dev, "failed to get clock\n");
117 return ret;
118 }
119
120 clock = clk_get_rate(&clk);
121 if (IS_ERR_VALUE(clock)) {
122 dev_err(dev, "failed to get rate\n");
123 return clock;
124 }
125 debug("%s: CLK %ld\n", __func__, clock);
126
127 ret = clk_enable(&clk);
128 if (ret && ret != -ENOSYS) {
129 dev_err(dev, "failed to enable clock\n");
130 return ret;
131 }
132
133 _uart_zynq_serial_setbrg(priv->regs, clock, baudrate);
134
135 return 0;
136 }
137
zynq_serial_probe(struct udevice * dev)138 static int zynq_serial_probe(struct udevice *dev)
139 {
140 struct zynq_uart_priv *priv = dev_get_priv(dev);
141
142 /* No need to reinitialize the UART after relocation */
143 if (gd->flags & GD_FLG_RELOC)
144 return 0;
145
146 _uart_zynq_serial_init(priv->regs);
147
148 return 0;
149 }
150
zynq_serial_getc(struct udevice * dev)151 static int zynq_serial_getc(struct udevice *dev)
152 {
153 struct zynq_uart_priv *priv = dev_get_priv(dev);
154 struct uart_zynq *regs = priv->regs;
155
156 if (readl(®s->channel_sts) & ZYNQ_UART_SR_RXEMPTY)
157 return -EAGAIN;
158
159 return readl(®s->tx_rx_fifo);
160 }
161
zynq_serial_putc(struct udevice * dev,const char ch)162 static int zynq_serial_putc(struct udevice *dev, const char ch)
163 {
164 struct zynq_uart_priv *priv = dev_get_priv(dev);
165
166 return _uart_zynq_serial_putc(priv->regs, ch);
167 }
168
zynq_serial_pending(struct udevice * dev,bool input)169 static int zynq_serial_pending(struct udevice *dev, bool input)
170 {
171 struct zynq_uart_priv *priv = dev_get_priv(dev);
172 struct uart_zynq *regs = priv->regs;
173
174 if (input)
175 return !(readl(®s->channel_sts) & ZYNQ_UART_SR_RXEMPTY);
176 else
177 return !!(readl(®s->channel_sts) & ZYNQ_UART_SR_TXACTIVE);
178 }
179
zynq_serial_ofdata_to_platdata(struct udevice * dev)180 static int zynq_serial_ofdata_to_platdata(struct udevice *dev)
181 {
182 struct zynq_uart_priv *priv = dev_get_priv(dev);
183
184 priv->regs = (struct uart_zynq *)dev_read_addr(dev);
185 if (IS_ERR(priv->regs))
186 return PTR_ERR(priv->regs);
187
188 return 0;
189 }
190
191 static const struct dm_serial_ops zynq_serial_ops = {
192 .putc = zynq_serial_putc,
193 .pending = zynq_serial_pending,
194 .getc = zynq_serial_getc,
195 .setbrg = zynq_serial_setbrg,
196 };
197
198 static const struct udevice_id zynq_serial_ids[] = {
199 { .compatible = "xlnx,xuartps" },
200 { .compatible = "cdns,uart-r1p8" },
201 { .compatible = "cdns,uart-r1p12" },
202 { }
203 };
204
205 U_BOOT_DRIVER(serial_zynq) = {
206 .name = "serial_zynq",
207 .id = UCLASS_SERIAL,
208 .of_match = zynq_serial_ids,
209 .ofdata_to_platdata = zynq_serial_ofdata_to_platdata,
210 .priv_auto_alloc_size = sizeof(struct zynq_uart_priv),
211 .probe = zynq_serial_probe,
212 .ops = &zynq_serial_ops,
213 .flags = DM_FLAG_PRE_RELOC,
214 };
215
216 #ifdef CONFIG_DEBUG_UART_ZYNQ
_debug_uart_init(void)217 static inline void _debug_uart_init(void)
218 {
219 struct uart_zynq *regs = (struct uart_zynq *)CONFIG_DEBUG_UART_BASE;
220
221 _uart_zynq_serial_init(regs);
222 _uart_zynq_serial_setbrg(regs, CONFIG_DEBUG_UART_CLOCK,
223 CONFIG_BAUDRATE);
224 }
225
_debug_uart_putc(int ch)226 static inline void _debug_uart_putc(int ch)
227 {
228 struct uart_zynq *regs = (struct uart_zynq *)CONFIG_DEBUG_UART_BASE;
229
230 while (_uart_zynq_serial_putc(regs, ch) == -EAGAIN)
231 WATCHDOG_RESET();
232 }
233
234 DEBUG_UART_FUNCS
235
236 #endif
237