summaryrefslogtreecommitdiff
path: root/drivers/tty/serial/8250/8250_uniphier.c
blob: 6399a38ecce2ada62168872b33b13ae7c7273b49 (plain)
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
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright (C) 2015 Masahiro Yamada <yamada.masahiro@socionext.com>
 */

#include <linux/clk.h>
#include <linux/console.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>

#include "8250.h"

/*
 * This hardware is similar to 8250, but its register map is a bit different:
 *   - MMIO32 (regshift = 2)
 *   - FCR is not at 2, but 3
 *   - LCR and MCR are not at 3 and 4, they share 4
 *   - No SCR (Instead, CHAR can be used as a scratch register)
 *   - Divisor latch at 9, no divisor latch access bit
 */

#define UNIPHIER_UART_REGSHIFT		2

/* bit[15:8] = CHAR, bit[7:0] = FCR */
#define UNIPHIER_UART_CHAR_FCR		(3 << (UNIPHIER_UART_REGSHIFT))
/* bit[15:8] = LCR, bit[7:0] = MCR */
#define UNIPHIER_UART_LCR_MCR		(4 << (UNIPHIER_UART_REGSHIFT))
/* Divisor Latch Register */
#define UNIPHIER_UART_DLR		(9 << (UNIPHIER_UART_REGSHIFT))

struct uniphier8250_priv {
	int line;
	struct clk *clk;
	spinlock_t atomic_write_lock;
};

#ifdef CONFIG_SERIAL_8250_CONSOLE
static int __init uniphier_early_console_setup(struct earlycon_device *device,
					       const char *options)
{
	if (!device->port.membase)
		return -ENODEV;

	/* This hardware always expects MMIO32 register interface. */
	device->port.iotype = UPIO_MEM32;
	device->port.regshift = UNIPHIER_UART_REGSHIFT;

	/*
	 * Do not touch the divisor register in early_serial8250_setup();
	 * we assume it has been initialized by a boot loader.
	 */
	device->baud = 0;

	return early_serial8250_setup(device, options);
}
OF_EARLYCON_DECLARE(uniphier, "socionext,uniphier-uart",
		    uniphier_early_console_setup);
#endif

/*
 * The register map is slightly different from that of 8250.
 * IO callbacks must be overridden for correct access to FCR, LCR, MCR and SCR.
 */
static unsigned int uniphier_serial_in(struct uart_port *p, int offset)
{
	unsigned int valshift = 0;

	switch (offset) {
	case UART_SCR:
		/* No SCR for this hardware.  Use CHAR as a scratch register */
		valshift = 8;
		offset = UNIPHIER_UART_CHAR_FCR;
		break;
	case UART_LCR:
		valshift = 8;
		fallthrough;
	case UART_MCR:
		offset = UNIPHIER_UART_LCR_MCR;
		break;
	default:
		offset <<= UNIPHIER_UART_REGSHIFT;
		break;
	}

	/*
	 * The return value must be masked with 0xff because some registers
	 * share the same offset that must be accessed by 32-bit write/read.
	 * 8 or 16 bit access to this hardware result in unexpected behavior.
	 */
	return (readl(p->membase + offset) >> valshift) & 0xff;
}

static void uniphier_serial_out(struct uart_port *p, int offset, int value)
{
	unsigned int valshift = 0;
	bool normal = false;

	switch (offset) {
	case UART_SCR:
		/* No SCR for this hardware.  Use CHAR as a scratch register */
		valshift = 8;
		fallthrough;
	case UART_FCR:
		offset = UNIPHIER_UART_CHAR_FCR;
		break;
	case UART_LCR:
		valshift = 8;
		/* Divisor latch access bit does not exist. */
		value &= ~UART_LCR_DLAB;
		fallthrough;
	case UART_MCR:
		offset = UNIPHIER_UART_LCR_MCR;
		break;
	default:
		offset <<= UNIPHIER_UART_REGSHIFT;
		normal = true;
		break;
	}

	if (normal) {
		writel(value, p->membase + offset);
	} else {
		/*
		 * Special case: two registers share the same address that
		 * must be 32-bit accessed.  As this is not longer atomic safe,
		 * take a lock just in case.
		 */
		struct uniphier8250_priv *priv = p->private_data;
		unsigned long flags;
		u32 tmp;

		spin_lock_irqsave(&priv->atomic_write_lock, flags);
		tmp = readl(p->membase + offset);
		tmp &= ~(0xff << valshift);
		tmp |= value << valshift;
		writel(tmp, p->membase + offset);
		spin_unlock_irqrestore(&priv->atomic_write_lock, flags);
	}
}

/*
 * This hardware does not have the divisor latch access bit.
 * The divisor latch register exists at different address.
 * Override dl_read/write callbacks.
 */
static u32 uniphier_serial_dl_read(struct uart_8250_port *up)
{
	return readl(up->port.membase + UNIPHIER_UART_DLR);
}

static void uniphier_serial_dl_write(struct uart_8250_port *up, u32 value)
{
	writel(value, up->port.membase + UNIPHIER_UART_DLR);
}

static int uniphier_uart_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct uart_8250_port up;
	struct uniphier8250_priv *priv;
	struct resource *regs;
	void __iomem *membase;
	int irq;
	int ret;

	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!regs) {
		dev_err(dev, "failed to get memory resource\n");
		return -EINVAL;
	}

	membase = devm_ioremap(dev, regs->start, resource_size(regs));
	if (!membase)
		return -ENOMEM;

	irq = platform_get_irq(pdev, 0);
	if (irq < 0)
		return irq;

	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
	if (!priv)
		return -ENOMEM;

	memset(&up, 0, sizeof(up));

	ret = of_alias_get_id(dev->of_node, "serial");
	if (ret < 0) {
		dev_err(dev, "failed to get alias id\n");
		return ret;
	}
	up.port.line = ret;

	priv->clk = devm_clk_get(dev, NULL);
	if (IS_ERR(priv->clk)) {
		dev_err(dev, "failed to get clock\n");
		return PTR_ERR(priv->clk);
	}

	ret = clk_prepare_enable(priv->clk);
	if (ret)
		return ret;

	up.port.uartclk = clk_get_rate(priv->clk);

	spin_lock_init(&priv->atomic_write_lock);

	up.port.dev = dev;
	up.port.private_data = priv;
	up.port.mapbase = regs->start;
	up.port.mapsize = resource_size(regs);
	up.port.membase = membase;
	up.port.irq = irq;

	up.port.type = PORT_16550A;
	up.port.iotype = UPIO_MEM32;
	up.port.fifosize = 64;
	up.port.regshift = UNIPHIER_UART_REGSHIFT;
	up.port.flags = UPF_FIXED_PORT | UPF_FIXED_TYPE;
	up.capabilities = UART_CAP_FIFO;

	if (of_property_read_bool(dev->of_node, "auto-flow-control"))
		up.capabilities |= UART_CAP_AFE;

	up.port.serial_in = uniphier_serial_in;
	up.port.serial_out = uniphier_serial_out;
	up.dl_read = uniphier_serial_dl_read;
	up.dl_write = uniphier_serial_dl_write;

	ret = serial8250_register_8250_port(&up);
	if (ret < 0) {
		dev_err(dev, "failed to register 8250 port\n");
		clk_disable_unprepare(priv->clk);
		return ret;
	}
	priv->line = ret;

	platform_set_drvdata(pdev, priv);

	return 0;
}

static void uniphier_uart_remove(struct platform_device *pdev)
{
	struct uniphier8250_priv *priv = platform_get_drvdata(pdev);

	serial8250_unregister_port(priv->line);
	clk_disable_unprepare(priv->clk);
}

static int __maybe_unused uniphier_uart_suspend(struct device *dev)
{
	struct uniphier8250_priv *priv = dev_get_drvdata(dev);
	struct uart_8250_port *up = serial8250_get_port(priv->line);

	serial8250_suspend_port(priv->line);

	if (!uart_console(&up->port) || console_suspend_enabled)
		clk_disable_unprepare(priv->clk);

	return 0;
}

static int __maybe_unused uniphier_uart_resume(struct device *dev)
{
	struct uniphier8250_priv *priv = dev_get_drvdata(dev);
	struct uart_8250_port *up = serial8250_get_port(priv->line);
	int ret;

	if (!uart_console(&up->port) || console_suspend_enabled) {
		ret = clk_prepare_enable(priv->clk);
		if (ret)
			return ret;
	}

	serial8250_resume_port(priv->line);

	return 0;
}

static const struct dev_pm_ops uniphier_uart_pm_ops = {
	SET_SYSTEM_SLEEP_PM_OPS(uniphier_uart_suspend, uniphier_uart_resume)
};

static const struct of_device_id uniphier_uart_match[] = {
	{ .compatible = "socionext,uniphier-uart" },
	{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, uniphier_uart_match);

static struct platform_driver uniphier_uart_platform_driver = {
	.probe		= uniphier_uart_probe,
	.remove_new	= uniphier_uart_remove,
	.driver = {
		.name	= "uniphier-uart",
		.of_match_table = uniphier_uart_match,
		.pm = &uniphier_uart_pm_ops,
	},
};
module_platform_driver(uniphier_uart_platform_driver);

MODULE_AUTHOR("Masahiro Yamada <yamada.masahiro@socionext.com>");
MODULE_DESCRIPTION("UniPhier UART driver");
MODULE_LICENSE("GPL");