xref: /openbmc/u-boot/drivers/serial/serial_owl.c (revision 224f7452)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * Actions Semi OWL SoCs UART driver
4  *
5  * Copyright (C) 2015 Actions Semi Co., Ltd.
6  * Copyright (C) 2018 Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
7  */
8 
9 #include <common.h>
10 #include <clk.h>
11 #include <dm.h>
12 #include <errno.h>
13 #include <fdtdec.h>
14 #include <serial.h>
15 #include <asm/io.h>
16 #include <asm/types.h>
17 
18 /* UART Registers */
19 #define	OWL_UART_CTL			(0x0000)
20 #define	OWL_UART_RXDAT			(0x0004)
21 #define	OWL_UART_TXDAT			(0x0008)
22 #define	OWL_UART_STAT			(0x000C)
23 
24 /* UART_CTL Register Definitions */
25 #define	OWL_UART_CTL_PRS_NONE		GENMASK(6, 4)
26 #define	OWL_UART_CTL_STPS		BIT(2)
27 #define	OWL_UART_CTL_DWLS		3
28 
29 /* UART_STAT Register Definitions */
30 #define	OWL_UART_STAT_TFES		BIT(10)	/* TX FIFO Empty Status	*/
31 #define	OWL_UART_STAT_RFFS		BIT(9)	/* RX FIFO full	Status */
32 #define	OWL_UART_STAT_TFFU		BIT(6)	/* TX FIFO full	Status */
33 #define	OWL_UART_STAT_RFEM		BIT(5)	/* RX FIFO Empty Status	*/
34 
35 struct owl_serial_priv {
36 	phys_addr_t base;
37 };
38 
39 int owl_serial_setbrg(struct udevice *dev, int baudrate)
40 {
41 	/* Driver supports only fixed baudrate */
42 	return 0;
43 }
44 
45 static int owl_serial_getc(struct udevice *dev)
46 {
47 	struct owl_serial_priv *priv = dev_get_priv(dev);
48 
49 	if (readl(priv->base + OWL_UART_STAT) & OWL_UART_STAT_RFEM)
50 		return -EAGAIN;
51 
52 	return (int)(readl(priv->base +	OWL_UART_RXDAT));
53 }
54 
55 static int owl_serial_putc(struct udevice *dev,	const char ch)
56 {
57 	struct owl_serial_priv *priv = dev_get_priv(dev);
58 
59 	if (readl(priv->base + OWL_UART_STAT) & OWL_UART_STAT_TFFU)
60 		return -EAGAIN;
61 
62 	writel(ch, priv->base +	OWL_UART_TXDAT);
63 
64 	return 0;
65 }
66 
67 static int owl_serial_pending(struct udevice *dev, bool	input)
68 {
69 	struct owl_serial_priv *priv = dev_get_priv(dev);
70 	unsigned int stat = readl(priv->base + OWL_UART_STAT);
71 
72 	if (input)
73 		return !(stat &	OWL_UART_STAT_RFEM);
74 	else
75 		return !(stat &	OWL_UART_STAT_TFES);
76 }
77 
78 static int owl_serial_probe(struct udevice *dev)
79 {
80 	struct owl_serial_priv *priv = dev_get_priv(dev);
81 	struct clk clk;
82 	u32 uart_ctl;
83 	int ret;
84 
85 	/* Set data, parity and stop bits */
86 	uart_ctl = readl(priv->base + OWL_UART_CTL);
87 	uart_ctl &= ~(OWL_UART_CTL_PRS_NONE);
88 	uart_ctl &= ~(OWL_UART_CTL_STPS);
89 	uart_ctl |= OWL_UART_CTL_DWLS;
90 	writel(uart_ctl, priv->base + OWL_UART_CTL);
91 
92 	/* Enable UART clock */
93 	ret = clk_get_by_index(dev, 0, &clk);
94 	if (ret < 0)
95 		return ret;
96 
97 	ret = clk_enable(&clk);
98 	if (ret < 0)
99 		return ret;
100 
101 	return 0;
102 }
103 
104 static int owl_serial_ofdata_to_platdata(struct	udevice	*dev)
105 {
106 	struct owl_serial_priv *priv = dev_get_priv(dev);
107 
108 	priv->base = dev_read_addr(dev);
109 	if (priv->base == FDT_ADDR_T_NONE)
110 		return -EINVAL;
111 
112 	return 0;
113 }
114 
115 static const struct dm_serial_ops owl_serial_ops = {
116 	.putc =	owl_serial_putc,
117 	.pending = owl_serial_pending,
118 	.getc =	owl_serial_getc,
119 	.setbrg	= owl_serial_setbrg,
120 };
121 
122 static const struct udevice_id owl_serial_ids[] = {
123 	{ .compatible =	"actions,s900-serial" },
124 	{ }
125 };
126 
127 U_BOOT_DRIVER(serial_owl) = {
128 	.name = "serial_owl",
129 	.id = UCLASS_SERIAL,
130 	.of_match = owl_serial_ids,
131 	.ofdata_to_platdata = owl_serial_ofdata_to_platdata,
132 	.priv_auto_alloc_size =	sizeof(struct owl_serial_priv),
133 	.probe = owl_serial_probe,
134 	.ops = &owl_serial_ops,
135 };
136