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83d290c5 | 1 | // SPDX-License-Identifier: GPL-2.0+ |
3917c269 SW |
2 | /* |
3 | * (C) Copyright 2016 Stephen Warren <swarren@wwwdotorg.org> | |
4 | * | |
5 | * Derived from pl01x code: | |
6 | * | |
7 | * (C) Copyright 2000 | |
8 | * Rob Taylor, Flying Pig Systems. robt@flyingpig.com. | |
9 | * | |
10 | * (C) Copyright 2004 | |
11 | * ARM Ltd. | |
12 | * Philippe Robin, <philippe.robin@arm.com> | |
3917c269 SW |
13 | */ |
14 | ||
15 | /* Simple U-Boot driver for the BCM283x mini UART */ | |
16 | ||
17 | #include <common.h> | |
18 | #include <dm.h> | |
19 | #include <errno.h> | |
20 | #include <watchdog.h> | |
9dfeffe2 | 21 | #include <asm/gpio.h> |
3917c269 SW |
22 | #include <asm/io.h> |
23 | #include <serial.h> | |
24 | #include <dm/platform_data/serial_bcm283x_mu.h> | |
9dfeffe2 | 25 | #include <dm/pinctrl.h> |
cd93d625 | 26 | #include <linux/bitops.h> |
3917c269 | 27 | #include <linux/compiler.h> |
9f755f5d | 28 | |
3917c269 SW |
29 | struct bcm283x_mu_regs { |
30 | u32 io; | |
31 | u32 iir; | |
32 | u32 ier; | |
33 | u32 lcr; | |
34 | u32 mcr; | |
35 | u32 lsr; | |
36 | u32 msr; | |
37 | u32 scratch; | |
38 | u32 cntl; | |
39 | u32 stat; | |
40 | u32 baud; | |
41 | }; | |
42 | ||
43 | #define BCM283X_MU_LCR_DATA_SIZE_8 3 | |
44 | ||
45 | #define BCM283X_MU_LSR_TX_IDLE BIT(6) | |
46 | /* This actually means not full, but is named not empty in the docs */ | |
47 | #define BCM283X_MU_LSR_TX_EMPTY BIT(5) | |
48 | #define BCM283X_MU_LSR_RX_READY BIT(0) | |
49 | ||
50 | struct bcm283x_mu_priv { | |
51 | struct bcm283x_mu_regs *regs; | |
52 | }; | |
53 | ||
293b9814 AG |
54 | static int bcm283x_mu_serial_getc(struct udevice *dev); |
55 | ||
3917c269 SW |
56 | static int bcm283x_mu_serial_setbrg(struct udevice *dev, int baudrate) |
57 | { | |
58 | struct bcm283x_mu_serial_platdata *plat = dev_get_platdata(dev); | |
59 | struct bcm283x_mu_priv *priv = dev_get_priv(dev); | |
60 | struct bcm283x_mu_regs *regs = priv->regs; | |
61 | u32 divider; | |
62 | ||
fc8523a1 | 63 | if (plat->skip_init) |
293b9814 | 64 | goto out; |
3917c269 SW |
65 | |
66 | divider = plat->clock / (baudrate * 8); | |
67 | ||
68 | writel(BCM283X_MU_LCR_DATA_SIZE_8, ®s->lcr); | |
69 | writel(divider - 1, ®s->baud); | |
70 | ||
293b9814 AG |
71 | out: |
72 | /* Flush the RX queue - all data in there is bogus */ | |
73 | while (bcm283x_mu_serial_getc(dev) != -EAGAIN) ; | |
74 | ||
3917c269 SW |
75 | return 0; |
76 | } | |
77 | ||
3917c269 SW |
78 | static int bcm283x_mu_serial_getc(struct udevice *dev) |
79 | { | |
80 | struct bcm283x_mu_priv *priv = dev_get_priv(dev); | |
81 | struct bcm283x_mu_regs *regs = priv->regs; | |
82 | u32 data; | |
83 | ||
84 | /* Wait until there is data in the FIFO */ | |
85 | if (!(readl(®s->lsr) & BCM283X_MU_LSR_RX_READY)) | |
86 | return -EAGAIN; | |
87 | ||
88 | data = readl(®s->io); | |
89 | ||
90 | return (int)data; | |
91 | } | |
92 | ||
93 | static int bcm283x_mu_serial_putc(struct udevice *dev, const char data) | |
94 | { | |
95 | struct bcm283x_mu_priv *priv = dev_get_priv(dev); | |
96 | struct bcm283x_mu_regs *regs = priv->regs; | |
97 | ||
98 | /* Wait until there is space in the FIFO */ | |
99 | if (!(readl(®s->lsr) & BCM283X_MU_LSR_TX_EMPTY)) | |
100 | return -EAGAIN; | |
101 | ||
102 | /* Send the character */ | |
103 | writel(data, ®s->io); | |
104 | ||
105 | return 0; | |
106 | } | |
107 | ||
108 | static int bcm283x_mu_serial_pending(struct udevice *dev, bool input) | |
109 | { | |
110 | struct bcm283x_mu_priv *priv = dev_get_priv(dev); | |
111 | struct bcm283x_mu_regs *regs = priv->regs; | |
cb97ad47 FV |
112 | unsigned int lsr; |
113 | ||
cb97ad47 | 114 | lsr = readl(®s->lsr); |
3917c269 SW |
115 | |
116 | if (input) { | |
117 | WATCHDOG_RESET(); | |
e3a46e3e | 118 | return (lsr & BCM283X_MU_LSR_RX_READY) ? 1 : 0; |
3917c269 | 119 | } else { |
e3a46e3e | 120 | return (lsr & BCM283X_MU_LSR_TX_IDLE) ? 0 : 1; |
3917c269 SW |
121 | } |
122 | } | |
123 | ||
124 | static const struct dm_serial_ops bcm283x_mu_serial_ops = { | |
125 | .putc = bcm283x_mu_serial_putc, | |
126 | .pending = bcm283x_mu_serial_pending, | |
127 | .getc = bcm283x_mu_serial_getc, | |
128 | .setbrg = bcm283x_mu_serial_setbrg, | |
129 | }; | |
130 | ||
9f755f5d FV |
131 | #if CONFIG_IS_ENABLED(OF_CONTROL) |
132 | static const struct udevice_id bcm283x_mu_serial_id[] = { | |
133 | {.compatible = "brcm,bcm2835-aux-uart"}, | |
134 | {} | |
135 | }; | |
136 | ||
9dfeffe2 AG |
137 | /* |
138 | * Check if this serial device is muxed | |
139 | * | |
140 | * The serial device will only work properly if it has been muxed to the serial | |
141 | * pins by firmware. Check whether that happened here. | |
142 | * | |
143 | * @return true if serial device is muxed, false if not | |
144 | */ | |
145 | static bool bcm283x_is_serial_muxed(void) | |
146 | { | |
147 | int serial_gpio = 15; | |
148 | struct udevice *dev; | |
149 | ||
150 | if (uclass_first_device(UCLASS_PINCTRL, &dev) || !dev) | |
151 | return false; | |
152 | ||
153 | if (pinctrl_get_gpio_mux(dev, 0, serial_gpio) != BCM2835_GPIO_ALT5) | |
154 | return false; | |
155 | ||
156 | return true; | |
157 | } | |
158 | ||
0ed0db98 | 159 | static int bcm283x_mu_serial_probe(struct udevice *dev) |
9f755f5d FV |
160 | { |
161 | struct bcm283x_mu_serial_platdata *plat = dev_get_platdata(dev); | |
0ed0db98 | 162 | struct bcm283x_mu_priv *priv = dev_get_priv(dev); |
9f755f5d FV |
163 | fdt_addr_t addr; |
164 | ||
9dfeffe2 AG |
165 | /* Don't spawn the device if it's not muxed */ |
166 | if (!bcm283x_is_serial_muxed()) | |
167 | return -ENODEV; | |
168 | ||
0ed0db98 SG |
169 | /* |
170 | * Read the ofdata here rather than in an ofdata_to_platdata() method | |
171 | * since we need the soc simple-bus to be probed so that the 'ranges' | |
172 | * property is used. | |
173 | */ | |
2548493a | 174 | addr = dev_read_addr(dev); |
9f755f5d FV |
175 | if (addr == FDT_ADDR_T_NONE) |
176 | return -EINVAL; | |
177 | ||
178 | plat->base = addr; | |
80d5001c | 179 | plat->clock = dev_read_u32_default(dev, "clock", 1); |
bceab8d5 AG |
180 | |
181 | /* | |
182 | * TODO: Reinitialization doesn't always work for now, just skip | |
183 | * init always - we know we're already initialized | |
184 | */ | |
185 | plat->skip_init = true; | |
80d5001c | 186 | |
0ed0db98 SG |
187 | priv->regs = (struct bcm283x_mu_regs *)plat->base; |
188 | ||
9f755f5d FV |
189 | return 0; |
190 | } | |
191 | #endif | |
192 | ||
3917c269 SW |
193 | U_BOOT_DRIVER(serial_bcm283x_mu) = { |
194 | .name = "serial_bcm283x_mu", | |
195 | .id = UCLASS_SERIAL, | |
9f755f5d | 196 | .of_match = of_match_ptr(bcm283x_mu_serial_id), |
3917c269 SW |
197 | .platdata_auto_alloc_size = sizeof(struct bcm283x_mu_serial_platdata), |
198 | .probe = bcm283x_mu_serial_probe, | |
199 | .ops = &bcm283x_mu_serial_ops, | |
3f8b8e30 | 200 | #if !CONFIG_IS_ENABLED(OF_CONTROL) || CONFIG_IS_ENABLED(OF_BOARD) |
3917c269 | 201 | .flags = DM_FLAG_PRE_RELOC, |
46879196 | 202 | #endif |
3917c269 SW |
203 | .priv_auto_alloc_size = sizeof(struct bcm283x_mu_priv), |
204 | }; |