1 /*
2  * (C) Copyright 2016 Stephen Warren <swarren@wwwdotorg.org>
3  *
4  * Derived from pl01x code:
5  *
6  * (C) Copyright 2000
7  * Rob Taylor, Flying Pig Systems. robt@flyingpig.com.
8  *
9  * (C) Copyright 2004
10  * ARM Ltd.
11  * Philippe Robin, <philippe.robin@arm.com>
12  *
13  * SPDX-License-Identifier:	GPL-2.0+
14  */
15 
16 /* Simple U-Boot driver for the BCM283x mini UART */
17 
18 #include <common.h>
19 #include <dm.h>
20 #include <errno.h>
21 #include <watchdog.h>
22 #include <asm/io.h>
23 #include <serial.h>
24 #include <dm/platform_data/serial_bcm283x_mu.h>
25 #include <linux/compiler.h>
26 #include <fdtdec.h>
27 
28 struct bcm283x_mu_regs {
29 	u32 io;
30 	u32 iir;
31 	u32 ier;
32 	u32 lcr;
33 	u32 mcr;
34 	u32 lsr;
35 	u32 msr;
36 	u32 scratch;
37 	u32 cntl;
38 	u32 stat;
39 	u32 baud;
40 };
41 
42 #define BCM283X_MU_LCR_DATA_SIZE_8	3
43 
44 #define BCM283X_MU_LSR_TX_IDLE		BIT(6)
45 /* This actually means not full, but is named not empty in the docs */
46 #define BCM283X_MU_LSR_TX_EMPTY		BIT(5)
47 #define BCM283X_MU_LSR_RX_READY		BIT(0)
48 
49 struct bcm283x_mu_priv {
50 	struct bcm283x_mu_regs *regs;
51 };
52 
53 static int bcm283x_mu_serial_setbrg(struct udevice *dev, int baudrate)
54 {
55 	struct bcm283x_mu_serial_platdata *plat = dev_get_platdata(dev);
56 	struct bcm283x_mu_priv *priv = dev_get_priv(dev);
57 	struct bcm283x_mu_regs *regs = priv->regs;
58 	u32 divider;
59 
60 	if (plat->skip_init)
61 		return 0;
62 
63 	divider = plat->clock / (baudrate * 8);
64 
65 	writel(BCM283X_MU_LCR_DATA_SIZE_8, &regs->lcr);
66 	writel(divider - 1, &regs->baud);
67 
68 	return 0;
69 }
70 
71 static int bcm283x_mu_serial_probe(struct udevice *dev)
72 {
73 	struct bcm283x_mu_serial_platdata *plat = dev_get_platdata(dev);
74 	struct bcm283x_mu_priv *priv = dev_get_priv(dev);
75 
76 	if (plat->disabled)
77 		return -ENODEV;
78 
79 	priv->regs = (struct bcm283x_mu_regs *)plat->base;
80 
81 	return 0;
82 }
83 
84 static int bcm283x_mu_serial_getc(struct udevice *dev)
85 {
86 	struct bcm283x_mu_priv *priv = dev_get_priv(dev);
87 	struct bcm283x_mu_regs *regs = priv->regs;
88 	u32 data;
89 
90 	/* Wait until there is data in the FIFO */
91 	if (!(readl(&regs->lsr) & BCM283X_MU_LSR_RX_READY))
92 		return -EAGAIN;
93 
94 	data = readl(&regs->io);
95 
96 	return (int)data;
97 }
98 
99 static int bcm283x_mu_serial_putc(struct udevice *dev, const char data)
100 {
101 	struct bcm283x_mu_priv *priv = dev_get_priv(dev);
102 	struct bcm283x_mu_regs *regs = priv->regs;
103 
104 	/* Wait until there is space in the FIFO */
105 	if (!(readl(&regs->lsr) & BCM283X_MU_LSR_TX_EMPTY))
106 		return -EAGAIN;
107 
108 	/* Send the character */
109 	writel(data, &regs->io);
110 
111 	return 0;
112 }
113 
114 static int bcm283x_mu_serial_pending(struct udevice *dev, bool input)
115 {
116 	struct bcm283x_mu_priv *priv = dev_get_priv(dev);
117 	struct bcm283x_mu_regs *regs = priv->regs;
118 	unsigned int lsr = readl(&regs->lsr);
119 
120 	if (input) {
121 		WATCHDOG_RESET();
122 		return (lsr & BCM283X_MU_LSR_RX_READY) ? 1 : 0;
123 	} else {
124 		return (lsr & BCM283X_MU_LSR_TX_IDLE) ? 0 : 1;
125 	}
126 }
127 
128 static const struct dm_serial_ops bcm283x_mu_serial_ops = {
129 	.putc = bcm283x_mu_serial_putc,
130 	.pending = bcm283x_mu_serial_pending,
131 	.getc = bcm283x_mu_serial_getc,
132 	.setbrg = bcm283x_mu_serial_setbrg,
133 };
134 
135 U_BOOT_DRIVER(serial_bcm283x_mu) = {
136 	.name = "serial_bcm283x_mu",
137 	.id = UCLASS_SERIAL,
138 	.platdata_auto_alloc_size = sizeof(struct bcm283x_mu_serial_platdata),
139 	.probe = bcm283x_mu_serial_probe,
140 	.ops = &bcm283x_mu_serial_ops,
141 	.flags = DM_FLAG_PRE_RELOC,
142 	.priv_auto_alloc_size = sizeof(struct bcm283x_mu_priv),
143 };
144