1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * Copyright (C) 2015 Masahiro Yamada <yamada.masahiro@socionext.com>
4 */
5
6 #include <linux/clk.h>
7 #include <linux/console.h>
8 #include <linux/io.h>
9 #include <linux/module.h>
10 #include <linux/of.h>
11 #include <linux/platform_device.h>
12
13 #include "8250.h"
14
15 /*
16 * This hardware is similar to 8250, but its register map is a bit different:
17 * - MMIO32 (regshift = 2)
18 * - FCR is not at 2, but 3
19 * - LCR and MCR are not at 3 and 4, they share 4
20 * - No SCR (Instead, CHAR can be used as a scratch register)
21 * - Divisor latch at 9, no divisor latch access bit
22 */
23
24 #define UNIPHIER_UART_REGSHIFT 2
25
26 /* bit[15:8] = CHAR, bit[7:0] = FCR */
27 #define UNIPHIER_UART_CHAR_FCR (3 << (UNIPHIER_UART_REGSHIFT))
28 /* bit[15:8] = LCR, bit[7:0] = MCR */
29 #define UNIPHIER_UART_LCR_MCR (4 << (UNIPHIER_UART_REGSHIFT))
30 /* Divisor Latch Register */
31 #define UNIPHIER_UART_DLR (9 << (UNIPHIER_UART_REGSHIFT))
32
33 struct uniphier8250_priv {
34 int line;
35 struct clk *clk;
36 spinlock_t atomic_write_lock;
37 };
38
39 #ifdef CONFIG_SERIAL_8250_CONSOLE
uniphier_early_console_setup(struct earlycon_device * device,const char * options)40 static int __init uniphier_early_console_setup(struct earlycon_device *device,
41 const char *options)
42 {
43 if (!device->port.membase)
44 return -ENODEV;
45
46 /* This hardware always expects MMIO32 register interface. */
47 device->port.iotype = UPIO_MEM32;
48 device->port.regshift = UNIPHIER_UART_REGSHIFT;
49
50 /*
51 * Do not touch the divisor register in early_serial8250_setup();
52 * we assume it has been initialized by a boot loader.
53 */
54 device->baud = 0;
55
56 return early_serial8250_setup(device, options);
57 }
58 OF_EARLYCON_DECLARE(uniphier, "socionext,uniphier-uart",
59 uniphier_early_console_setup);
60 #endif
61
62 /*
63 * The register map is slightly different from that of 8250.
64 * IO callbacks must be overridden for correct access to FCR, LCR, MCR and SCR.
65 */
uniphier_serial_in(struct uart_port * p,int offset)66 static unsigned int uniphier_serial_in(struct uart_port *p, int offset)
67 {
68 unsigned int valshift = 0;
69
70 switch (offset) {
71 case UART_SCR:
72 /* No SCR for this hardware. Use CHAR as a scratch register */
73 valshift = 8;
74 offset = UNIPHIER_UART_CHAR_FCR;
75 break;
76 case UART_LCR:
77 valshift = 8;
78 fallthrough;
79 case UART_MCR:
80 offset = UNIPHIER_UART_LCR_MCR;
81 break;
82 default:
83 offset <<= UNIPHIER_UART_REGSHIFT;
84 break;
85 }
86
87 /*
88 * The return value must be masked with 0xff because some registers
89 * share the same offset that must be accessed by 32-bit write/read.
90 * 8 or 16 bit access to this hardware result in unexpected behavior.
91 */
92 return (readl(p->membase + offset) >> valshift) & 0xff;
93 }
94
uniphier_serial_out(struct uart_port * p,int offset,int value)95 static void uniphier_serial_out(struct uart_port *p, int offset, int value)
96 {
97 unsigned int valshift = 0;
98 bool normal = false;
99
100 switch (offset) {
101 case UART_SCR:
102 /* No SCR for this hardware. Use CHAR as a scratch register */
103 valshift = 8;
104 fallthrough;
105 case UART_FCR:
106 offset = UNIPHIER_UART_CHAR_FCR;
107 break;
108 case UART_LCR:
109 valshift = 8;
110 /* Divisor latch access bit does not exist. */
111 value &= ~UART_LCR_DLAB;
112 fallthrough;
113 case UART_MCR:
114 offset = UNIPHIER_UART_LCR_MCR;
115 break;
116 default:
117 offset <<= UNIPHIER_UART_REGSHIFT;
118 normal = true;
119 break;
120 }
121
122 if (normal) {
123 writel(value, p->membase + offset);
124 } else {
125 /*
126 * Special case: two registers share the same address that
127 * must be 32-bit accessed. As this is not longer atomic safe,
128 * take a lock just in case.
129 */
130 struct uniphier8250_priv *priv = p->private_data;
131 unsigned long flags;
132 u32 tmp;
133
134 spin_lock_irqsave(&priv->atomic_write_lock, flags);
135 tmp = readl(p->membase + offset);
136 tmp &= ~(0xff << valshift);
137 tmp |= value << valshift;
138 writel(tmp, p->membase + offset);
139 spin_unlock_irqrestore(&priv->atomic_write_lock, flags);
140 }
141 }
142
143 /*
144 * This hardware does not have the divisor latch access bit.
145 * The divisor latch register exists at different address.
146 * Override dl_read/write callbacks.
147 */
uniphier_serial_dl_read(struct uart_8250_port * up)148 static u32 uniphier_serial_dl_read(struct uart_8250_port *up)
149 {
150 return readl(up->port.membase + UNIPHIER_UART_DLR);
151 }
152
uniphier_serial_dl_write(struct uart_8250_port * up,u32 value)153 static void uniphier_serial_dl_write(struct uart_8250_port *up, u32 value)
154 {
155 writel(value, up->port.membase + UNIPHIER_UART_DLR);
156 }
157
uniphier_uart_probe(struct platform_device * pdev)158 static int uniphier_uart_probe(struct platform_device *pdev)
159 {
160 struct device *dev = &pdev->dev;
161 struct uart_8250_port up;
162 struct uniphier8250_priv *priv;
163 struct resource *regs;
164 void __iomem *membase;
165 int ret;
166
167 regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
168 if (!regs) {
169 dev_err(dev, "failed to get memory resource\n");
170 return -EINVAL;
171 }
172
173 membase = devm_ioremap(dev, regs->start, resource_size(regs));
174 if (!membase)
175 return -ENOMEM;
176
177 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
178 if (!priv)
179 return -ENOMEM;
180
181 memset(&up, 0, sizeof(up));
182
183 priv->clk = devm_clk_get(dev, NULL);
184 if (IS_ERR(priv->clk)) {
185 dev_err(dev, "failed to get clock\n");
186 return PTR_ERR(priv->clk);
187 }
188
189 ret = clk_prepare_enable(priv->clk);
190 if (ret)
191 return ret;
192
193 up.port.uartclk = clk_get_rate(priv->clk);
194
195 spin_lock_init(&priv->atomic_write_lock);
196
197 up.port.dev = dev;
198 up.port.private_data = priv;
199 up.port.mapbase = regs->start;
200 up.port.mapsize = resource_size(regs);
201 up.port.membase = membase;
202
203 ret = uart_read_port_properties(&up.port);
204 if (ret)
205 return ret;
206
207 up.port.type = PORT_16550A;
208 up.port.iotype = UPIO_MEM32;
209 up.port.fifosize = 64;
210 up.port.regshift = UNIPHIER_UART_REGSHIFT;
211 up.port.flags = UPF_FIXED_PORT | UPF_FIXED_TYPE;
212 up.capabilities = UART_CAP_FIFO;
213
214 if (of_property_read_bool(dev->of_node, "auto-flow-control"))
215 up.capabilities |= UART_CAP_AFE;
216
217 up.port.serial_in = uniphier_serial_in;
218 up.port.serial_out = uniphier_serial_out;
219 up.dl_read = uniphier_serial_dl_read;
220 up.dl_write = uniphier_serial_dl_write;
221
222 ret = serial8250_register_8250_port(&up);
223 if (ret < 0) {
224 dev_err(dev, "failed to register 8250 port\n");
225 clk_disable_unprepare(priv->clk);
226 return ret;
227 }
228 priv->line = ret;
229
230 platform_set_drvdata(pdev, priv);
231
232 return 0;
233 }
234
uniphier_uart_remove(struct platform_device * pdev)235 static void uniphier_uart_remove(struct platform_device *pdev)
236 {
237 struct uniphier8250_priv *priv = platform_get_drvdata(pdev);
238
239 serial8250_unregister_port(priv->line);
240 clk_disable_unprepare(priv->clk);
241 }
242
uniphier_uart_suspend(struct device * dev)243 static int __maybe_unused uniphier_uart_suspend(struct device *dev)
244 {
245 struct uniphier8250_priv *priv = dev_get_drvdata(dev);
246 struct uart_8250_port *up = serial8250_get_port(priv->line);
247
248 serial8250_suspend_port(priv->line);
249
250 if (!uart_console(&up->port) || console_suspend_enabled)
251 clk_disable_unprepare(priv->clk);
252
253 return 0;
254 }
255
uniphier_uart_resume(struct device * dev)256 static int __maybe_unused uniphier_uart_resume(struct device *dev)
257 {
258 struct uniphier8250_priv *priv = dev_get_drvdata(dev);
259 struct uart_8250_port *up = serial8250_get_port(priv->line);
260 int ret;
261
262 if (!uart_console(&up->port) || console_suspend_enabled) {
263 ret = clk_prepare_enable(priv->clk);
264 if (ret)
265 return ret;
266 }
267
268 serial8250_resume_port(priv->line);
269
270 return 0;
271 }
272
273 static const struct dev_pm_ops uniphier_uart_pm_ops = {
274 SET_SYSTEM_SLEEP_PM_OPS(uniphier_uart_suspend, uniphier_uart_resume)
275 };
276
277 static const struct of_device_id uniphier_uart_match[] = {
278 { .compatible = "socionext,uniphier-uart" },
279 { /* sentinel */ }
280 };
281 MODULE_DEVICE_TABLE(of, uniphier_uart_match);
282
283 static struct platform_driver uniphier_uart_platform_driver = {
284 .probe = uniphier_uart_probe,
285 .remove = uniphier_uart_remove,
286 .driver = {
287 .name = "uniphier-uart",
288 .of_match_table = uniphier_uart_match,
289 .pm = &uniphier_uart_pm_ops,
290 },
291 };
292 module_platform_driver(uniphier_uart_platform_driver);
293
294 MODULE_AUTHOR("Masahiro Yamada <yamada.masahiro@socionext.com>");
295 MODULE_DESCRIPTION("UniPhier UART driver");
296 MODULE_LICENSE("GPL");
297