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  */
22 static bool bcm283x_is_serial_muxed(void)
23 {
24 	int serial_gpio = 15;
25 	struct udevice *dev;
26 
27 	if (uclass_first_device(UCLASS_PINCTRL, &dev) || !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 
36 static int bcm283x_pl011_serial_ofdata_to_platdata(struct udevice *dev)
37 {
38 	struct pl01x_serial_platdata *plat = dev_get_platdata(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 	ret = pl01x_serial_ofdata_to_platdata(dev);
46 	if (ret)
47 		return ret;
48 
49 	/*
50 	 * TODO: Reinitialization doesn't always work for now, just skip
51 	 *       init always - we know we're already initialized
52 	 */
53 	plat->skip_init = true;
54 
55 	return 0;
56 }
57 
58 static int bcm283x_pl011_serial_setbrg(struct udevice *dev, int baudrate)
59 {
60 	int r;
61 
62 	r = pl01x_serial_setbrg(dev, baudrate);
63 
64 	/*
65 	 * We may have been muxed to a bogus line before. Drain the RX
66 	 * queue so we start at a clean slate.
67 	 */
68 	while (pl01x_serial_getc(dev) != -EAGAIN) ;
69 
70 	return r;
71 }
72 
73 static const struct dm_serial_ops bcm283x_pl011_serial_ops = {
74 	.putc = pl01x_serial_putc,
75 	.pending = pl01x_serial_pending,
76 	.getc = pl01x_serial_getc,
77 	.setbrg = bcm283x_pl011_serial_setbrg,
78 };
79 
80 static const struct udevice_id bcm283x_pl011_serial_id[] = {
81 	{.compatible = "brcm,bcm2835-pl011", .data = TYPE_PL011},
82 	{}
83 };
84 
85 U_BOOT_DRIVER(bcm283x_pl011_uart) = {
86 	.name	= "bcm283x_pl011",
87 	.id	= UCLASS_SERIAL,
88 	.of_match = of_match_ptr(bcm283x_pl011_serial_id),
89 	.ofdata_to_platdata = of_match_ptr(bcm283x_pl011_serial_ofdata_to_platdata),
90 	.platdata_auto_alloc_size = sizeof(struct pl01x_serial_platdata),
91 	.probe	= pl01x_serial_probe,
92 	.ops	= &bcm283x_pl011_serial_ops,
93 	.flags	= DM_FLAG_PRE_RELOC,
94 	.priv_auto_alloc_size = sizeof(struct pl01x_priv),
95 };
96