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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(*priv), 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_obj(*kb_serio);
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_obj(*pad_serio);
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 = 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);