1 // SPDX-License-Identifier: GPL-2.0-only
2 /* linux/drivers/char/pc8736x_gpio.c
3 
4    National Semiconductor PC8736x GPIO driver.  Allows a user space
5    process to play with the GPIO pins.
6 
7    Copyright (c) 2005,2006 Jim Cromie <jim.cromie@gmail.com>
8 
9    adapted from linux/drivers/char/scx200_gpio.c
10    Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com>,
11 */
12 
13 #include <linux/fs.h>
14 #include <linux/module.h>
15 #include <linux/errno.h>
16 #include <linux/kernel.h>
17 #include <linux/init.h>
18 #include <linux/cdev.h>
19 #include <linux/io.h>
20 #include <linux/ioport.h>
21 #include <linux/mutex.h>
22 #include <linux/nsc_gpio.h>
23 #include <linux/platform_device.h>
24 #include <linux/uaccess.h>
25 
26 #define DEVNAME "pc8736x_gpio"
27 
28 MODULE_AUTHOR("Jim Cromie <jim.cromie@gmail.com>");
29 MODULE_DESCRIPTION("NatSemi/Winbond PC-8736x GPIO Pin Driver");
30 MODULE_LICENSE("GPL");
31 
32 static int major;		/* default to dynamic major */
33 module_param(major, int, 0);
34 MODULE_PARM_DESC(major, "Major device number");
35 
36 static DEFINE_MUTEX(pc8736x_gpio_config_lock);
37 static unsigned pc8736x_gpio_base;
38 static u8 pc8736x_gpio_shadow[4];
39 
40 #define SIO_BASE1       0x2E	/* 1st command-reg to check */
41 #define SIO_BASE2       0x4E	/* alt command-reg to check */
42 
43 #define SIO_SID		0x20	/* SuperI/O ID Register */
44 #define SIO_SID_PC87365	0xe5	/* Expected value in ID Register for PC87365 */
45 #define SIO_SID_PC87366	0xe9	/* Expected value in ID Register for PC87366 */
46 
47 #define SIO_CF1		0x21	/* chip config, bit0 is chip enable */
48 
49 #define PC8736X_GPIO_RANGE	16 /* ioaddr range */
50 #define PC8736X_GPIO_CT		32 /* minors matching 4 8 bit ports */
51 
52 #define SIO_UNIT_SEL	0x7	/* unit select reg */
53 #define SIO_UNIT_ACT	0x30	/* unit enable */
54 #define SIO_GPIO_UNIT	0x7	/* unit number of GPIO */
55 #define SIO_VLM_UNIT	0x0D
56 #define SIO_TMS_UNIT	0x0E
57 
58 /* config-space addrs to read/write each unit's runtime addr */
59 #define SIO_BASE_HADDR		0x60
60 #define SIO_BASE_LADDR		0x61
61 
62 /* GPIO config-space pin-control addresses */
63 #define SIO_GPIO_PIN_SELECT	0xF0
64 #define SIO_GPIO_PIN_CONFIG     0xF1
65 #define SIO_GPIO_PIN_EVENT      0xF2
66 
67 static unsigned char superio_cmd = 0;
68 static unsigned char selected_device = 0xFF;	/* bogus start val */
69 
70 /* GPIO port runtime access, functionality */
71 static int port_offset[] = { 0, 4, 8, 10 };	/* non-uniform offsets ! */
72 /* static int event_capable[] = { 1, 1, 0, 0 };   ports 2,3 are hobbled */
73 
74 #define PORT_OUT	0
75 #define PORT_IN		1
76 #define PORT_EVT_EN	2
77 #define PORT_EVT_STST	3
78 
79 static struct platform_device *pdev;  /* use in dev_*() */
80 
superio_outb(int addr,int val)81 static inline void superio_outb(int addr, int val)
82 {
83 	outb_p(addr, superio_cmd);
84 	outb_p(val, superio_cmd + 1);
85 }
86 
superio_inb(int addr)87 static inline int superio_inb(int addr)
88 {
89 	outb_p(addr, superio_cmd);
90 	return inb_p(superio_cmd + 1);
91 }
92 
pc8736x_superio_present(void)93 static int pc8736x_superio_present(void)
94 {
95 	int id;
96 
97 	/* try the 2 possible values, read a hardware reg to verify */
98 	superio_cmd = SIO_BASE1;
99 	id = superio_inb(SIO_SID);
100 	if (id == SIO_SID_PC87365 || id == SIO_SID_PC87366)
101 		return superio_cmd;
102 
103 	superio_cmd = SIO_BASE2;
104 	id = superio_inb(SIO_SID);
105 	if (id == SIO_SID_PC87365 || id == SIO_SID_PC87366)
106 		return superio_cmd;
107 
108 	return 0;
109 }
110 
device_select(unsigned devldn)111 static void device_select(unsigned devldn)
112 {
113 	superio_outb(SIO_UNIT_SEL, devldn);
114 	selected_device = devldn;
115 }
116 
select_pin(unsigned iminor)117 static void select_pin(unsigned iminor)
118 {
119 	/* select GPIO port/pin from device minor number */
120 	device_select(SIO_GPIO_UNIT);
121 	superio_outb(SIO_GPIO_PIN_SELECT,
122 		     ((iminor << 1) & 0xF0) | (iminor & 0x7));
123 }
124 
pc8736x_gpio_configure_fn(unsigned index,u32 mask,u32 bits,u32 func_slct)125 static inline u32 pc8736x_gpio_configure_fn(unsigned index, u32 mask, u32 bits,
126 					    u32 func_slct)
127 {
128 	u32 config, new_config;
129 
130 	mutex_lock(&pc8736x_gpio_config_lock);
131 
132 	device_select(SIO_GPIO_UNIT);
133 	select_pin(index);
134 
135 	/* read current config value */
136 	config = superio_inb(func_slct);
137 
138 	/* set new config */
139 	new_config = (config & mask) | bits;
140 	superio_outb(func_slct, new_config);
141 
142 	mutex_unlock(&pc8736x_gpio_config_lock);
143 
144 	return config;
145 }
146 
pc8736x_gpio_configure(unsigned index,u32 mask,u32 bits)147 static u32 pc8736x_gpio_configure(unsigned index, u32 mask, u32 bits)
148 {
149 	return pc8736x_gpio_configure_fn(index, mask, bits,
150 					 SIO_GPIO_PIN_CONFIG);
151 }
152 
pc8736x_gpio_get(unsigned minor)153 static int pc8736x_gpio_get(unsigned minor)
154 {
155 	int port, bit, val;
156 
157 	port = minor >> 3;
158 	bit = minor & 7;
159 	val = inb_p(pc8736x_gpio_base + port_offset[port] + PORT_IN);
160 	val >>= bit;
161 	val &= 1;
162 
163 	dev_dbg(&pdev->dev, "_gpio_get(%d from %x bit %d) == val %d\n",
164 		minor, pc8736x_gpio_base + port_offset[port] + PORT_IN, bit,
165 		val);
166 
167 	return val;
168 }
169 
pc8736x_gpio_set(unsigned minor,int val)170 static void pc8736x_gpio_set(unsigned minor, int val)
171 {
172 	int port, bit, curval;
173 
174 	minor &= 0x1f;
175 	port = minor >> 3;
176 	bit = minor & 7;
177 	curval = inb_p(pc8736x_gpio_base + port_offset[port] + PORT_OUT);
178 
179 	dev_dbg(&pdev->dev, "addr:%x cur:%x bit-pos:%d cur-bit:%x + new:%d -> bit-new:%d\n",
180 		pc8736x_gpio_base + port_offset[port] + PORT_OUT,
181 		curval, bit, (curval & ~(1 << bit)), val, (val << bit));
182 
183 	val = (curval & ~(1 << bit)) | (val << bit);
184 
185 	dev_dbg(&pdev->dev, "gpio_set(minor:%d port:%d bit:%d)"
186 		" %2x -> %2x\n", minor, port, bit, curval, val);
187 
188 	outb_p(val, pc8736x_gpio_base + port_offset[port] + PORT_OUT);
189 
190 	curval = inb_p(pc8736x_gpio_base + port_offset[port] + PORT_OUT);
191 	val = inb_p(pc8736x_gpio_base + port_offset[port] + PORT_IN);
192 
193 	dev_dbg(&pdev->dev, "wrote %x, read: %x\n", curval, val);
194 	pc8736x_gpio_shadow[port] = val;
195 }
196 
pc8736x_gpio_current(unsigned minor)197 static int pc8736x_gpio_current(unsigned minor)
198 {
199 	int port, bit;
200 	minor &= 0x1f;
201 	port = minor >> 3;
202 	bit = minor & 7;
203 	return ((pc8736x_gpio_shadow[port] >> bit) & 0x01);
204 }
205 
pc8736x_gpio_change(unsigned index)206 static void pc8736x_gpio_change(unsigned index)
207 {
208 	pc8736x_gpio_set(index, !pc8736x_gpio_current(index));
209 }
210 
211 static struct nsc_gpio_ops pc8736x_gpio_ops = {
212 	.owner		= THIS_MODULE,
213 	.gpio_config	= pc8736x_gpio_configure,
214 	.gpio_dump	= nsc_gpio_dump,
215 	.gpio_get	= pc8736x_gpio_get,
216 	.gpio_set	= pc8736x_gpio_set,
217 	.gpio_change	= pc8736x_gpio_change,
218 	.gpio_current	= pc8736x_gpio_current
219 };
220 
pc8736x_gpio_open(struct inode * inode,struct file * file)221 static int pc8736x_gpio_open(struct inode *inode, struct file *file)
222 {
223 	unsigned m = iminor(inode);
224 	file->private_data = &pc8736x_gpio_ops;
225 
226 	dev_dbg(&pdev->dev, "open %d\n", m);
227 
228 	if (m >= PC8736X_GPIO_CT)
229 		return -EINVAL;
230 	return nonseekable_open(inode, file);
231 }
232 
233 static const struct file_operations pc8736x_gpio_fileops = {
234 	.owner	= THIS_MODULE,
235 	.open	= pc8736x_gpio_open,
236 	.write	= nsc_gpio_write,
237 	.read	= nsc_gpio_read,
238 	.llseek = no_llseek,
239 };
240 
pc8736x_init_shadow(void)241 static void __init pc8736x_init_shadow(void)
242 {
243 	int port;
244 
245 	/* read the current values driven on the GPIO signals */
246 	for (port = 0; port < 4; ++port)
247 		pc8736x_gpio_shadow[port]
248 		    = inb_p(pc8736x_gpio_base + port_offset[port]
249 			    + PORT_OUT);
250 
251 }
252 
253 static struct cdev pc8736x_gpio_cdev;
254 
pc8736x_gpio_init(void)255 static int __init pc8736x_gpio_init(void)
256 {
257 	int rc;
258 	dev_t devid;
259 
260 	pdev = platform_device_alloc(DEVNAME, 0);
261 	if (!pdev)
262 		return -ENOMEM;
263 
264 	rc = platform_device_add(pdev);
265 	if (rc) {
266 		rc = -ENODEV;
267 		goto undo_platform_dev_alloc;
268 	}
269 	dev_info(&pdev->dev, "NatSemi pc8736x GPIO Driver Initializing\n");
270 
271 	if (!pc8736x_superio_present()) {
272 		rc = -ENODEV;
273 		dev_err(&pdev->dev, "no device found\n");
274 		goto undo_platform_dev_add;
275 	}
276 	pc8736x_gpio_ops.dev = &pdev->dev;
277 
278 	/* Verify that chip and it's GPIO unit are both enabled.
279 	   My BIOS does this, so I take minimum action here
280 	 */
281 	rc = superio_inb(SIO_CF1);
282 	if (!(rc & 0x01)) {
283 		rc = -ENODEV;
284 		dev_err(&pdev->dev, "device not enabled\n");
285 		goto undo_platform_dev_add;
286 	}
287 	device_select(SIO_GPIO_UNIT);
288 	if (!superio_inb(SIO_UNIT_ACT)) {
289 		rc = -ENODEV;
290 		dev_err(&pdev->dev, "GPIO unit not enabled\n");
291 		goto undo_platform_dev_add;
292 	}
293 
294 	/* read the GPIO unit base addr that chip responds to */
295 	pc8736x_gpio_base = (superio_inb(SIO_BASE_HADDR) << 8
296 			     | superio_inb(SIO_BASE_LADDR));
297 
298 	if (!request_region(pc8736x_gpio_base, PC8736X_GPIO_RANGE, DEVNAME)) {
299 		rc = -ENODEV;
300 		dev_err(&pdev->dev, "GPIO ioport %x busy\n",
301 			pc8736x_gpio_base);
302 		goto undo_platform_dev_add;
303 	}
304 	dev_info(&pdev->dev, "GPIO ioport %x reserved\n", pc8736x_gpio_base);
305 
306 	if (major) {
307 		devid = MKDEV(major, 0);
308 		rc = register_chrdev_region(devid, PC8736X_GPIO_CT, DEVNAME);
309 	} else {
310 		rc = alloc_chrdev_region(&devid, 0, PC8736X_GPIO_CT, DEVNAME);
311 		major = MAJOR(devid);
312 	}
313 
314 	if (rc < 0) {
315 		dev_err(&pdev->dev, "register-chrdev failed: %d\n", rc);
316 		goto undo_request_region;
317 	}
318 	if (!major) {
319 		major = rc;
320 		dev_dbg(&pdev->dev, "got dynamic major %d\n", major);
321 	}
322 
323 	pc8736x_init_shadow();
324 
325 	/* ignore minor errs, and succeed */
326 	cdev_init(&pc8736x_gpio_cdev, &pc8736x_gpio_fileops);
327 	cdev_add(&pc8736x_gpio_cdev, devid, PC8736X_GPIO_CT);
328 
329 	return 0;
330 
331 undo_request_region:
332 	release_region(pc8736x_gpio_base, PC8736X_GPIO_RANGE);
333 undo_platform_dev_add:
334 	platform_device_del(pdev);
335 undo_platform_dev_alloc:
336 	platform_device_put(pdev);
337 
338 	return rc;
339 }
340 
pc8736x_gpio_cleanup(void)341 static void __exit pc8736x_gpio_cleanup(void)
342 {
343 	dev_dbg(&pdev->dev, "cleanup\n");
344 
345 	cdev_del(&pc8736x_gpio_cdev);
346 	unregister_chrdev_region(MKDEV(major,0), PC8736X_GPIO_CT);
347 	release_region(pc8736x_gpio_base, PC8736X_GPIO_RANGE);
348 
349 	platform_device_unregister(pdev);
350 }
351 
352 module_init(pc8736x_gpio_init);
353 module_exit(pc8736x_gpio_cleanup);
354