1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * Copyright (c) 2018 Alexander Graf <agraf@suse.de>
4 */
5
6#include <common.h>
7#include <dm.h>
8#include <asm/gpio.h>
9#include <dm/pinctrl.h>
10#include <dm/platform_data/serial_pl01x.h>
11#include <serial.h>
12#include "serial_pl01x_internal.h"
13
14/*
15 * Check if this serial device is muxed
16 *
17 * The serial device will only work properly if it has been muxed to the serial
18 * pins by firmware. Check whether that happened here.
19 *
20 * Return: true if serial device is muxed, false if not
21 */
22static bool bcm283x_is_serial_muxed(void)
23{
24	int serial_gpio = 15;
25	struct udevice *dev;
26
27	if (uclass_first_device_err(UCLASS_PINCTRL, &dev))
28		return false;
29
30	if (pinctrl_get_gpio_mux(dev, 0, serial_gpio) != BCM2835_GPIO_ALT0)
31		return false;
32
33	return true;
34}
35
36static int bcm283x_pl011_serial_probe(struct udevice *dev)
37{
38	struct pl01x_serial_plat *plat = dev_get_plat(dev);
39	int ret;
40
41	/* Don't spawn the device if it's not muxed */
42	if (!bcm283x_is_serial_muxed())
43		return -ENODEV;
44
45	/*
46	 * Read the ofdata here rather than in an of_to_plat() method
47	 * since we need the soc simple-bus to be probed so that the 'ranges'
48	 * property is used.
49	 */
50	ret = pl01x_serial_of_to_plat(dev);
51	if (ret)
52		return ret;
53
54	/*
55	 * TODO: Reinitialization doesn't always work for now, just skip
56	 *       init always - we know we're already initialized
57	 */
58	plat->skip_init = true;
59
60	return pl01x_serial_probe(dev);
61}
62
63static int bcm283x_pl011_serial_setbrg(struct udevice *dev, int baudrate)
64{
65	int r;
66
67	r = pl01x_serial_setbrg(dev, baudrate);
68
69	/*
70	 * We may have been muxed to a bogus line before. Drain the RX
71	 * queue so we start at a clean slate.
72	 */
73	while (pl01x_serial_getc(dev) != -EAGAIN) ;
74
75	return r;
76}
77
78static const struct dm_serial_ops bcm283x_pl011_serial_ops = {
79	.putc = pl01x_serial_putc,
80	.pending = pl01x_serial_pending,
81	.getc = pl01x_serial_getc,
82	.setbrg = bcm283x_pl011_serial_setbrg,
83};
84
85static const struct udevice_id bcm283x_pl011_serial_id[] = {
86	{.compatible = "brcm,bcm2835-pl011", .data = TYPE_PL011},
87	{}
88};
89
90U_BOOT_DRIVER(bcm283x_pl011_uart) = {
91	.name	= "bcm283x_pl011",
92	.id	= UCLASS_SERIAL,
93	.of_match = of_match_ptr(bcm283x_pl011_serial_id),
94	.probe	= bcm283x_pl011_serial_probe,
95	.plat_auto	= sizeof(struct pl01x_serial_plat),
96	.ops	= &bcm283x_pl011_serial_ops,
97#if !CONFIG_IS_ENABLED(OF_CONTROL) || IS_ENABLED(CONFIG_OF_BOARD)
98	.flags	= DM_FLAG_PRE_RELOC,
99#endif
100	.priv_auto	= sizeof(struct pl01x_priv),
101};
102