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Linux/drivers/input/serio/olpc_apsp.c

  1 /*
  2  * OLPC serio driver for multiplexed input from Marvell MMP security processor
  3  *
  4  * Copyright (C) 2011-2013 One Laptop Per Child
  5  *
  6  * This program is free software; you can redistribute it and/or modify
  7  * it under the terms of the GNU General Public License as published by
  8  * the Free Software Foundation; either version 2 of the License, or
  9  * (at your option) any later version.
 10  *
 11  * This program is distributed in the hope that it will be useful,
 12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 14  * GNU General Public License for more details.
 15  */
 16 
 17 #include <linux/module.h>
 18 #include <linux/interrupt.h>
 19 #include <linux/serio.h>
 20 #include <linux/err.h>
 21 #include <linux/platform_device.h>
 22 #include <linux/io.h>
 23 #include <linux/of.h>
 24 #include <linux/slab.h>
 25 #include <linux/delay.h>
 26 
 27 /*
 28  * The OLPC XO-1.75 and XO-4 laptops do not have a hardware PS/2 controller.
 29  * Instead, the OLPC firmware runs a bit-banging PS/2 implementation on an
 30  * otherwise-unused slow processor which is included in the Marvell MMP2/MMP3
 31  * SoC, known as the "Security Processor" (SP) or "Wireless Trusted Module"
 32  * (WTM). This firmware then reports its results via the WTM registers,
 33  * which we read from the Application Processor (AP, i.e. main CPU) in this
 34  * driver.
 35  *
 36  * On the hardware side we have a PS/2 mouse and an AT keyboard, the data
 37  * is multiplexed through this system. We create a serio port for each one,
 38  * and demultiplex the data accordingly.
 39  */
 40 
 41 /* WTM register offsets */
 42 #define SECURE_PROCESSOR_COMMAND        0x40
 43 #define COMMAND_RETURN_STATUS           0x80
 44 #define COMMAND_FIFO_STATUS             0xc4
 45 #define PJ_RST_INTERRUPT                0xc8
 46 #define PJ_INTERRUPT_MASK               0xcc
 47 
 48 /*
 49  * The upper byte of SECURE_PROCESSOR_COMMAND and COMMAND_RETURN_STATUS is
 50  * used to identify which port (device) is being talked to. The lower byte
 51  * is the data being sent/received.
 52  */
 53 #define PORT_MASK       0xff00
 54 #define DATA_MASK       0x00ff
 55 #define PORT_SHIFT      8
 56 #define KEYBOARD_PORT   0
 57 #define TOUCHPAD_PORT   1
 58 
 59 /* COMMAND_FIFO_STATUS */
 60 #define CMD_CNTR_MASK           0x7 /* Number of pending/unprocessed commands */
 61 #define MAX_PENDING_CMDS        4   /* from device specs */
 62 
 63 /* PJ_RST_INTERRUPT */
 64 #define SP_COMMAND_COMPLETE_RESET       0x1
 65 
 66 /* PJ_INTERRUPT_MASK */
 67 #define INT_0   (1 << 0)
 68 
 69 /* COMMAND_FIFO_STATUS */
 70 #define CMD_STS_MASK    0x100
 71 
 72 struct olpc_apsp {
 73         struct device *dev;
 74         struct serio *kbio;
 75         struct serio *padio;
 76         void __iomem *base;
 77         int open_count;
 78         int irq;
 79 };
 80 
 81 static int olpc_apsp_write(struct serio *port, unsigned char val)
 82 {
 83         struct olpc_apsp *priv = port->port_data;
 84         unsigned int i;
 85         u32 which = 0;
 86 
 87         if (port == priv->padio)
 88                 which = TOUCHPAD_PORT << PORT_SHIFT;
 89         else
 90                 which = KEYBOARD_PORT << PORT_SHIFT;
 91 
 92         dev_dbg(priv->dev, "olpc_apsp_write which=%x val=%x\n", which, val);
 93         for (i = 0; i < 50; i++) {
 94                 u32 sts = readl(priv->base + COMMAND_FIFO_STATUS);
 95                 if ((sts & CMD_CNTR_MASK) < MAX_PENDING_CMDS) {
 96                         writel(which | val,
 97                                priv->base + SECURE_PROCESSOR_COMMAND);
 98                         return 0;
 99                 }
100                 /* SP busy. This has not been seen in practice. */
101                 mdelay(1);
102         }
103 
104         dev_dbg(priv->dev, "olpc_apsp_write timeout, status=%x\n",
105                 readl(priv->base + COMMAND_FIFO_STATUS));
106 
107         return -ETIMEDOUT;
108 }
109 
110 static irqreturn_t olpc_apsp_rx(int irq, void *dev_id)
111 {
112         struct olpc_apsp *priv = dev_id;
113         unsigned int w, tmp;
114         struct serio *serio;
115 
116         /*
117          * Write 1 to PJ_RST_INTERRUPT to acknowledge and clear the interrupt
118          * Write 0xff00 to SECURE_PROCESSOR_COMMAND.
119          */
120         tmp = readl(priv->base + PJ_RST_INTERRUPT);
121         if (!(tmp & SP_COMMAND_COMPLETE_RESET)) {
122                 dev_warn(priv->dev, "spurious interrupt?\n");
123                 return IRQ_NONE;
124         }
125 
126         w = readl(priv->base + COMMAND_RETURN_STATUS);
127         dev_dbg(priv->dev, "olpc_apsp_rx %x\n", w);
128 
129         if (w >> PORT_SHIFT == KEYBOARD_PORT)
130                 serio = priv->kbio;
131         else
132                 serio = priv->padio;
133 
134         serio_interrupt(serio, w & DATA_MASK, 0);
135 
136         /* Ack and clear interrupt */
137         writel(tmp | SP_COMMAND_COMPLETE_RESET, priv->base + PJ_RST_INTERRUPT);
138         writel(PORT_MASK, priv->base + SECURE_PROCESSOR_COMMAND);
139 
140         pm_wakeup_event(priv->dev, 1000);
141         return IRQ_HANDLED;
142 }
143 
144 static int olpc_apsp_open(struct serio *port)
145 {
146         struct olpc_apsp *priv = port->port_data;
147         unsigned int tmp;
148 
149         if (priv->open_count++ == 0) {
150                 /* Enable interrupt 0 by clearing its bit */
151                 tmp = readl(priv->base + PJ_INTERRUPT_MASK);
152                 writel(tmp & ~INT_0, priv->base + PJ_INTERRUPT_MASK);
153         }
154 
155         return 0;
156 }
157 
158 static void olpc_apsp_close(struct serio *port)
159 {
160         struct olpc_apsp *priv = port->port_data;
161         unsigned int tmp;
162 
163         if (--priv->open_count == 0) {
164                 /* Disable interrupt 0 */
165                 tmp = readl(priv->base + PJ_INTERRUPT_MASK);
166                 writel(tmp | INT_0, priv->base + PJ_INTERRUPT_MASK);
167         }
168 }
169 
170 static int olpc_apsp_probe(struct platform_device *pdev)
171 {
172         struct serio *kb_serio, *pad_serio;
173         struct olpc_apsp *priv;
174         struct resource *res;
175         struct device_node *np;
176         unsigned long l;
177         int error;
178 
179         priv = devm_kzalloc(&pdev->dev, sizeof(struct olpc_apsp), GFP_KERNEL);
180         if (!priv)
181                 return -ENOMEM;
182 
183         np = pdev->dev.of_node;
184         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
185         priv->base = devm_ioremap_resource(&pdev->dev, res);
186         if (IS_ERR(priv->base)) {
187                 dev_err(&pdev->dev, "Failed to map WTM registers\n");
188                 return PTR_ERR(priv->base);
189         }
190 
191         priv->irq = platform_get_irq(pdev, 0);
192         if (priv->irq < 0)
193                 return priv->irq;
194 
195         l = readl(priv->base + COMMAND_FIFO_STATUS);
196         if (!(l & CMD_STS_MASK)) {
197                 dev_err(&pdev->dev, "SP cannot accept commands.\n");
198                 return -EIO;
199         }
200 
201         /* KEYBOARD */
202         kb_serio = kzalloc(sizeof(struct serio), GFP_KERNEL);
203         if (!kb_serio)
204                 return -ENOMEM;
205         kb_serio->id.type       = SERIO_8042_XL;
206         kb_serio->write         = olpc_apsp_write;
207         kb_serio->open          = olpc_apsp_open;
208         kb_serio->close         = olpc_apsp_close;
209         kb_serio->port_data     = priv;
210         kb_serio->dev.parent    = &pdev->dev;
211         strlcpy(kb_serio->name, "sp keyboard", sizeof(kb_serio->name));
212         strlcpy(kb_serio->phys, "sp/serio0", sizeof(kb_serio->phys));
213         priv->kbio              = kb_serio;
214         serio_register_port(kb_serio);
215 
216         /* TOUCHPAD */
217         pad_serio = kzalloc(sizeof(struct serio), GFP_KERNEL);
218         if (!pad_serio) {
219                 error = -ENOMEM;
220                 goto err_pad;
221         }
222         pad_serio->id.type      = SERIO_8042;
223         pad_serio->write        = olpc_apsp_write;
224         pad_serio->open         = olpc_apsp_open;
225         pad_serio->close        = olpc_apsp_close;
226         pad_serio->port_data    = priv;
227         pad_serio->dev.parent   = &pdev->dev;
228         strlcpy(pad_serio->name, "sp touchpad", sizeof(pad_serio->name));
229         strlcpy(pad_serio->phys, "sp/serio1", sizeof(pad_serio->phys));
230         priv->padio             = pad_serio;
231         serio_register_port(pad_serio);
232 
233         error = request_irq(priv->irq, olpc_apsp_rx, 0, "olpc-apsp", priv);
234         if (error) {
235                 dev_err(&pdev->dev, "Failed to request IRQ\n");
236                 goto err_irq;
237         }
238 
239         priv->dev = &pdev->dev;
240         device_init_wakeup(priv->dev, 1);
241         platform_set_drvdata(pdev, priv);
242 
243         dev_dbg(&pdev->dev, "probed successfully.\n");
244         return 0;
245 
246 err_irq:
247         serio_unregister_port(pad_serio);
248 err_pad:
249         serio_unregister_port(kb_serio);
250         return error;
251 }
252 
253 static int olpc_apsp_remove(struct platform_device *pdev)
254 {
255         struct olpc_apsp *priv = platform_get_drvdata(pdev);
256 
257         free_irq(priv->irq, priv);
258 
259         serio_unregister_port(priv->kbio);
260         serio_unregister_port(priv->padio);
261 
262         return 0;
263 }
264 
265 static const struct of_device_id olpc_apsp_dt_ids[] = {
266         { .compatible = "olpc,ap-sp", },
267         {}
268 };
269 MODULE_DEVICE_TABLE(of, olpc_apsp_dt_ids);
270 
271 static struct platform_driver olpc_apsp_driver = {
272         .probe          = olpc_apsp_probe,
273         .remove         = olpc_apsp_remove,
274         .driver         = {
275                 .name   = "olpc-apsp",
276                 .owner  = THIS_MODULE,
277                 .of_match_table = olpc_apsp_dt_ids,
278         },
279 };
280 
281 MODULE_DESCRIPTION("OLPC AP-SP serio driver");
282 MODULE_LICENSE("GPL");
283 module_platform_driver(olpc_apsp_driver);
284 

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