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
63struct 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
72static 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
101static 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
135static 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
156static 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
168static 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
234err_irq:
235	serio_unregister_port(pad_serio);
236err_pad:
237	serio_unregister_port(kb_serio);
238	return error;
239}
240
241static void 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
251static const struct of_device_id olpc_apsp_dt_ids[] = {
252	{ .compatible = "olpc,ap-sp", },
253	{}
254};
255MODULE_DEVICE_TABLE(of, olpc_apsp_dt_ids);
256
257static struct platform_driver olpc_apsp_driver = {
258	.probe		= olpc_apsp_probe,
259	.remove_new	= olpc_apsp_remove,
260	.driver		= {
261		.name	= "olpc-apsp",
262		.of_match_table = olpc_apsp_dt_ids,
263	},
264};
265
266MODULE_DESCRIPTION("OLPC AP-SP serio driver");
267MODULE_LICENSE("GPL");
268module_platform_driver(olpc_apsp_driver);
269