xref: /openbmc/linux/drivers/input/serio/olpc_apsp.c (revision 492ec555)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * OLPC serio driver for multiplexed input from Marvell MMP security processor
4  *
5  * Copyright (C) 2011-2013 One Laptop Per Child
6  */
7 
8 #include <linux/module.h>
9 #include <linux/interrupt.h>
10 #include <linux/serio.h>
11 #include <linux/err.h>
12 #include <linux/platform_device.h>
13 #include <linux/io.h>
14 #include <linux/of.h>
15 #include <linux/slab.h>
16 #include <linux/delay.h>
17 
18 /*
19  * The OLPC XO-1.75 and XO-4 laptops do not have a hardware PS/2 controller.
20  * Instead, the OLPC firmware runs a bit-banging PS/2 implementation on an
21  * otherwise-unused slow processor which is included in the Marvell MMP2/MMP3
22  * SoC, known as the "Security Processor" (SP) or "Wireless Trusted Module"
23  * (WTM). This firmware then reports its results via the WTM registers,
24  * which we read from the Application Processor (AP, i.e. main CPU) in this
25  * driver.
26  *
27  * On the hardware side we have a PS/2 mouse and an AT keyboard, the data
28  * is multiplexed through this system. We create a serio port for each one,
29  * and demultiplex the data accordingly.
30  */
31 
32 /* WTM register offsets */
33 #define SECURE_PROCESSOR_COMMAND	0x40
34 #define COMMAND_RETURN_STATUS		0x80
35 #define COMMAND_FIFO_STATUS		0xc4
36 #define PJ_RST_INTERRUPT		0xc8
37 #define PJ_INTERRUPT_MASK		0xcc
38 
39 /*
40  * The upper byte of SECURE_PROCESSOR_COMMAND and COMMAND_RETURN_STATUS is
41  * used to identify which port (device) is being talked to. The lower byte
42  * is the data being sent/received.
43  */
44 #define PORT_MASK	0xff00
45 #define DATA_MASK	0x00ff
46 #define PORT_SHIFT	8
47 #define KEYBOARD_PORT	0
48 #define TOUCHPAD_PORT	1
49 
50 /* COMMAND_FIFO_STATUS */
51 #define CMD_CNTR_MASK		0x7 /* Number of pending/unprocessed commands */
52 #define MAX_PENDING_CMDS	4   /* from device specs */
53 
54 /* PJ_RST_INTERRUPT */
55 #define SP_COMMAND_COMPLETE_RESET	0x1
56 
57 /* PJ_INTERRUPT_MASK */
58 #define INT_0	(1 << 0)
59 
60 /* COMMAND_FIFO_STATUS */
61 #define CMD_STS_MASK	0x100
62 
63 struct olpc_apsp {
64 	struct device *dev;
65 	struct serio *kbio;
66 	struct serio *padio;
67 	void __iomem *base;
68 	int open_count;
69 	int irq;
70 };
71 
olpc_apsp_write(struct serio * port,unsigned char val)72 static int olpc_apsp_write(struct serio *port, unsigned char val)
73 {
74 	struct olpc_apsp *priv = port->port_data;
75 	unsigned int i;
76 	u32 which = 0;
77 
78 	if (port == priv->padio)
79 		which = TOUCHPAD_PORT << PORT_SHIFT;
80 	else
81 		which = KEYBOARD_PORT << PORT_SHIFT;
82 
83 	dev_dbg(priv->dev, "olpc_apsp_write which=%x val=%x\n", which, val);
84 	for (i = 0; i < 50; i++) {
85 		u32 sts = readl(priv->base + COMMAND_FIFO_STATUS);
86 		if ((sts & CMD_CNTR_MASK) < MAX_PENDING_CMDS) {
87 			writel(which | val,
88 			       priv->base + SECURE_PROCESSOR_COMMAND);
89 			return 0;
90 		}
91 		/* SP busy. This has not been seen in practice. */
92 		mdelay(1);
93 	}
94 
95 	dev_dbg(priv->dev, "olpc_apsp_write timeout, status=%x\n",
96 		readl(priv->base + COMMAND_FIFO_STATUS));
97 
98 	return -ETIMEDOUT;
99 }
100 
olpc_apsp_rx(int irq,void * dev_id)101 static irqreturn_t olpc_apsp_rx(int irq, void *dev_id)
102 {
103 	struct olpc_apsp *priv = dev_id;
104 	unsigned int w, tmp;
105 	struct serio *serio;
106 
107 	/*
108 	 * Write 1 to PJ_RST_INTERRUPT to acknowledge and clear the interrupt
109 	 * Write 0xff00 to SECURE_PROCESSOR_COMMAND.
110 	 */
111 	tmp = readl(priv->base + PJ_RST_INTERRUPT);
112 	if (!(tmp & SP_COMMAND_COMPLETE_RESET)) {
113 		dev_warn(priv->dev, "spurious interrupt?\n");
114 		return IRQ_NONE;
115 	}
116 
117 	w = readl(priv->base + COMMAND_RETURN_STATUS);
118 	dev_dbg(priv->dev, "olpc_apsp_rx %x\n", w);
119 
120 	if (w >> PORT_SHIFT == KEYBOARD_PORT)
121 		serio = priv->kbio;
122 	else
123 		serio = priv->padio;
124 
125 	serio_interrupt(serio, w & DATA_MASK, 0);
126 
127 	/* Ack and clear interrupt */
128 	writel(tmp | SP_COMMAND_COMPLETE_RESET, priv->base + PJ_RST_INTERRUPT);
129 	writel(PORT_MASK, priv->base + SECURE_PROCESSOR_COMMAND);
130 
131 	pm_wakeup_event(priv->dev, 1000);
132 	return IRQ_HANDLED;
133 }
134 
olpc_apsp_open(struct serio * port)135 static int olpc_apsp_open(struct serio *port)
136 {
137 	struct olpc_apsp *priv = port->port_data;
138 	unsigned int tmp;
139 	unsigned long l;
140 
141 	if (priv->open_count++ == 0) {
142 		l = readl(priv->base + COMMAND_FIFO_STATUS);
143 		if (!(l & CMD_STS_MASK)) {
144 			dev_err(priv->dev, "SP cannot accept commands.\n");
145 			return -EIO;
146 		}
147 
148 		/* Enable interrupt 0 by clearing its bit */
149 		tmp = readl(priv->base + PJ_INTERRUPT_MASK);
150 		writel(tmp & ~INT_0, priv->base + PJ_INTERRUPT_MASK);
151 	}
152 
153 	return 0;
154 }
155 
olpc_apsp_close(struct serio * port)156 static void olpc_apsp_close(struct serio *port)
157 {
158 	struct olpc_apsp *priv = port->port_data;
159 	unsigned int tmp;
160 
161 	if (--priv->open_count == 0) {
162 		/* Disable interrupt 0 */
163 		tmp = readl(priv->base + PJ_INTERRUPT_MASK);
164 		writel(tmp | INT_0, priv->base + PJ_INTERRUPT_MASK);
165 	}
166 }
167 
olpc_apsp_probe(struct platform_device * pdev)168 static int olpc_apsp_probe(struct platform_device *pdev)
169 {
170 	struct serio *kb_serio, *pad_serio;
171 	struct olpc_apsp *priv;
172 	int error;
173 
174 	priv = devm_kzalloc(&pdev->dev, sizeof(struct olpc_apsp), GFP_KERNEL);
175 	if (!priv)
176 		return -ENOMEM;
177 
178 	priv->dev = &pdev->dev;
179 
180 	priv->base = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
181 	if (IS_ERR(priv->base)) {
182 		dev_err(&pdev->dev, "Failed to map WTM registers\n");
183 		return PTR_ERR(priv->base);
184 	}
185 
186 	priv->irq = platform_get_irq(pdev, 0);
187 	if (priv->irq < 0)
188 		return priv->irq;
189 
190 	/* KEYBOARD */
191 	kb_serio = kzalloc(sizeof(struct serio), GFP_KERNEL);
192 	if (!kb_serio)
193 		return -ENOMEM;
194 	kb_serio->id.type	= SERIO_8042_XL;
195 	kb_serio->write		= olpc_apsp_write;
196 	kb_serio->open		= olpc_apsp_open;
197 	kb_serio->close		= olpc_apsp_close;
198 	kb_serio->port_data	= priv;
199 	kb_serio->dev.parent	= &pdev->dev;
200 	strscpy(kb_serio->name, "sp keyboard", sizeof(kb_serio->name));
201 	strscpy(kb_serio->phys, "sp/serio0", sizeof(kb_serio->phys));
202 	priv->kbio		= kb_serio;
203 	serio_register_port(kb_serio);
204 
205 	/* TOUCHPAD */
206 	pad_serio = kzalloc(sizeof(struct serio), GFP_KERNEL);
207 	if (!pad_serio) {
208 		error = -ENOMEM;
209 		goto err_pad;
210 	}
211 	pad_serio->id.type	= SERIO_8042;
212 	pad_serio->write	= olpc_apsp_write;
213 	pad_serio->open		= olpc_apsp_open;
214 	pad_serio->close	= olpc_apsp_close;
215 	pad_serio->port_data	= priv;
216 	pad_serio->dev.parent	= &pdev->dev;
217 	strscpy(pad_serio->name, "sp touchpad", sizeof(pad_serio->name));
218 	strscpy(pad_serio->phys, "sp/serio1", sizeof(pad_serio->phys));
219 	priv->padio		= pad_serio;
220 	serio_register_port(pad_serio);
221 
222 	error = request_irq(priv->irq, olpc_apsp_rx, 0, "olpc-apsp", priv);
223 	if (error) {
224 		dev_err(&pdev->dev, "Failed to request IRQ\n");
225 		goto err_irq;
226 	}
227 
228 	device_init_wakeup(priv->dev, 1);
229 	platform_set_drvdata(pdev, priv);
230 
231 	dev_dbg(&pdev->dev, "probed successfully.\n");
232 	return 0;
233 
234 err_irq:
235 	serio_unregister_port(pad_serio);
236 err_pad:
237 	serio_unregister_port(kb_serio);
238 	return error;
239 }
240 
olpc_apsp_remove(struct platform_device * pdev)241 static int olpc_apsp_remove(struct platform_device *pdev)
242 {
243 	struct olpc_apsp *priv = platform_get_drvdata(pdev);
244 
245 	free_irq(priv->irq, priv);
246 
247 	serio_unregister_port(priv->kbio);
248 	serio_unregister_port(priv->padio);
249 
250 	return 0;
251 }
252 
253 static const struct of_device_id olpc_apsp_dt_ids[] = {
254 	{ .compatible = "olpc,ap-sp", },
255 	{}
256 };
257 MODULE_DEVICE_TABLE(of, olpc_apsp_dt_ids);
258 
259 static struct platform_driver olpc_apsp_driver = {
260 	.probe		= olpc_apsp_probe,
261 	.remove		= olpc_apsp_remove,
262 	.driver		= {
263 		.name	= "olpc-apsp",
264 		.of_match_table = olpc_apsp_dt_ids,
265 	},
266 };
267 
268 MODULE_DESCRIPTION("OLPC AP-SP serio driver");
269 MODULE_LICENSE("GPL");
270 module_platform_driver(olpc_apsp_driver);
271