1 /*
2  * PowerNV LPC bus handling.
3  *
4  * Copyright 2013 IBM Corp.
5  *
6  * This program is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU General Public License
8  * as published by the Free Software Foundation; either version
9  * 2 of the License, or (at your option) any later version.
10  */
11 
12 #include <linux/kernel.h>
13 #include <linux/of.h>
14 #include <linux/bug.h>
15 #include <linux/debugfs.h>
16 #include <linux/io.h>
17 #include <linux/slab.h>
18 
19 #include <asm/machdep.h>
20 #include <asm/firmware.h>
21 #include <asm/xics.h>
22 #include <asm/opal.h>
23 #include <asm/prom.h>
24 #include <asm/uaccess.h>
25 #include <asm/debug.h>
26 
27 static int opal_lpc_chip_id = -1;
28 
29 static u8 opal_lpc_inb(unsigned long port)
30 {
31 	int64_t rc;
32 	__be32 data;
33 
34 	if (opal_lpc_chip_id < 0 || port > 0xffff)
35 		return 0xff;
36 	rc = opal_lpc_read(opal_lpc_chip_id, OPAL_LPC_IO, port, &data, 1);
37 	return rc ? 0xff : be32_to_cpu(data);
38 }
39 
40 static __le16 __opal_lpc_inw(unsigned long port)
41 {
42 	int64_t rc;
43 	__be32 data;
44 
45 	if (opal_lpc_chip_id < 0 || port > 0xfffe)
46 		return 0xffff;
47 	if (port & 1)
48 		return (__le16)opal_lpc_inb(port) << 8 | opal_lpc_inb(port + 1);
49 	rc = opal_lpc_read(opal_lpc_chip_id, OPAL_LPC_IO, port, &data, 2);
50 	return rc ? 0xffff : be32_to_cpu(data);
51 }
52 static u16 opal_lpc_inw(unsigned long port)
53 {
54 	return le16_to_cpu(__opal_lpc_inw(port));
55 }
56 
57 static __le32 __opal_lpc_inl(unsigned long port)
58 {
59 	int64_t rc;
60 	__be32 data;
61 
62 	if (opal_lpc_chip_id < 0 || port > 0xfffc)
63 		return 0xffffffff;
64 	if (port & 3)
65 		return (__le32)opal_lpc_inb(port    ) << 24 |
66 		       (__le32)opal_lpc_inb(port + 1) << 16 |
67 		       (__le32)opal_lpc_inb(port + 2) <<  8 |
68 			       opal_lpc_inb(port + 3);
69 	rc = opal_lpc_read(opal_lpc_chip_id, OPAL_LPC_IO, port, &data, 4);
70 	return rc ? 0xffffffff : be32_to_cpu(data);
71 }
72 
73 static u32 opal_lpc_inl(unsigned long port)
74 {
75 	return le32_to_cpu(__opal_lpc_inl(port));
76 }
77 
78 static void opal_lpc_outb(u8 val, unsigned long port)
79 {
80 	if (opal_lpc_chip_id < 0 || port > 0xffff)
81 		return;
82 	opal_lpc_write(opal_lpc_chip_id, OPAL_LPC_IO, port, val, 1);
83 }
84 
85 static void __opal_lpc_outw(__le16 val, unsigned long port)
86 {
87 	if (opal_lpc_chip_id < 0 || port > 0xfffe)
88 		return;
89 	if (port & 1) {
90 		opal_lpc_outb(val >> 8, port);
91 		opal_lpc_outb(val     , port + 1);
92 		return;
93 	}
94 	opal_lpc_write(opal_lpc_chip_id, OPAL_LPC_IO, port, val, 2);
95 }
96 
97 static void opal_lpc_outw(u16 val, unsigned long port)
98 {
99 	__opal_lpc_outw(cpu_to_le16(val), port);
100 }
101 
102 static void __opal_lpc_outl(__le32 val, unsigned long port)
103 {
104 	if (opal_lpc_chip_id < 0 || port > 0xfffc)
105 		return;
106 	if (port & 3) {
107 		opal_lpc_outb(val >> 24, port);
108 		opal_lpc_outb(val >> 16, port + 1);
109 		opal_lpc_outb(val >>  8, port + 2);
110 		opal_lpc_outb(val      , port + 3);
111 		return;
112 	}
113 	opal_lpc_write(opal_lpc_chip_id, OPAL_LPC_IO, port, val, 4);
114 }
115 
116 static void opal_lpc_outl(u32 val, unsigned long port)
117 {
118 	__opal_lpc_outl(cpu_to_le32(val), port);
119 }
120 
121 static void opal_lpc_insb(unsigned long p, void *b, unsigned long c)
122 {
123 	u8 *ptr = b;
124 
125 	while(c--)
126 		*(ptr++) = opal_lpc_inb(p);
127 }
128 
129 static void opal_lpc_insw(unsigned long p, void *b, unsigned long c)
130 {
131 	__le16 *ptr = b;
132 
133 	while(c--)
134 		*(ptr++) = __opal_lpc_inw(p);
135 }
136 
137 static void opal_lpc_insl(unsigned long p, void *b, unsigned long c)
138 {
139 	__le32 *ptr = b;
140 
141 	while(c--)
142 		*(ptr++) = __opal_lpc_inl(p);
143 }
144 
145 static void opal_lpc_outsb(unsigned long p, const void *b, unsigned long c)
146 {
147 	const u8 *ptr = b;
148 
149 	while(c--)
150 		opal_lpc_outb(*(ptr++), p);
151 }
152 
153 static void opal_lpc_outsw(unsigned long p, const void *b, unsigned long c)
154 {
155 	const __le16 *ptr = b;
156 
157 	while(c--)
158 		__opal_lpc_outw(*(ptr++), p);
159 }
160 
161 static void opal_lpc_outsl(unsigned long p, const void *b, unsigned long c)
162 {
163 	const __le32 *ptr = b;
164 
165 	while(c--)
166 		__opal_lpc_outl(*(ptr++), p);
167 }
168 
169 static const struct ppc_pci_io opal_lpc_io = {
170 	.inb	= opal_lpc_inb,
171 	.inw	= opal_lpc_inw,
172 	.inl	= opal_lpc_inl,
173 	.outb	= opal_lpc_outb,
174 	.outw	= opal_lpc_outw,
175 	.outl	= opal_lpc_outl,
176 	.insb	= opal_lpc_insb,
177 	.insw	= opal_lpc_insw,
178 	.insl	= opal_lpc_insl,
179 	.outsb	= opal_lpc_outsb,
180 	.outsw	= opal_lpc_outsw,
181 	.outsl	= opal_lpc_outsl,
182 };
183 
184 #ifdef CONFIG_DEBUG_FS
185 struct lpc_debugfs_entry {
186 	enum OpalLPCAddressType lpc_type;
187 };
188 
189 static ssize_t lpc_debug_read(struct file *filp, char __user *ubuf,
190 			      size_t count, loff_t *ppos)
191 {
192 	struct lpc_debugfs_entry *lpc = filp->private_data;
193 	u32 data, pos, len, todo;
194 	int rc;
195 
196 	if (!access_ok(VERIFY_WRITE, ubuf, count))
197 		return -EFAULT;
198 
199 	todo = count;
200 	while (todo) {
201 		pos = *ppos;
202 
203 		/*
204 		 * Select access size based on count and alignment and
205 		 * access type. IO and MEM only support byte acceses,
206 		 * FW supports all 3.
207 		 */
208 		len = 1;
209 		if (lpc->lpc_type == OPAL_LPC_FW) {
210 			if (todo > 3 && (pos & 3) == 0)
211 				len = 4;
212 			else if (todo > 1 && (pos & 1) == 0)
213 				len = 2;
214 		}
215 		rc = opal_lpc_read(opal_lpc_chip_id, lpc->lpc_type, pos,
216 				   &data, len);
217 		if (rc)
218 			return -ENXIO;
219 
220 		/*
221 		 * Now there is some trickery with the data returned by OPAL
222 		 * as it's the desired data right justified in a 32-bit BE
223 		 * word.
224 		 *
225 		 * This is a very bad interface and I'm to blame for it :-(
226 		 *
227 		 * So we can't just apply a 32-bit swap to what comes from OPAL,
228 		 * because user space expects the *bytes* to be in their proper
229 		 * respective positions (ie, LPC position).
230 		 *
231 		 * So what we really want to do here is to shift data right
232 		 * appropriately on a LE kernel.
233 		 *
234 		 * IE. If the LPC transaction has bytes B0, B1, B2 and B3 in that
235 		 * order, we have in memory written to by OPAL at the "data"
236 		 * pointer:
237 		 *
238 		 *               Bytes:      OPAL "data"   LE "data"
239 		 *   32-bit:   B0 B1 B2 B3   B0B1B2B3      B3B2B1B0
240 		 *   16-bit:   B0 B1         0000B0B1      B1B00000
241 		 *    8-bit:   B0            000000B0      B0000000
242 		 *
243 		 * So a BE kernel will have the leftmost of the above in the MSB
244 		 * and rightmost in the LSB and can just then "cast" the u32 "data"
245 		 * down to the appropriate quantity and write it.
246 		 *
247 		 * However, an LE kernel can't. It doesn't need to swap because a
248 		 * load from data followed by a store to user are going to preserve
249 		 * the byte ordering which is the wire byte order which is what the
250 		 * user wants, but in order to "crop" to the right size, we need to
251 		 * shift right first.
252 		 */
253 		switch(len) {
254 		case 4:
255 			rc = __put_user((u32)data, (u32 __user *)ubuf);
256 			break;
257 		case 2:
258 #ifdef __LITTLE_ENDIAN__
259 			data >>= 16;
260 #endif
261 			rc = __put_user((u16)data, (u16 __user *)ubuf);
262 			break;
263 		default:
264 #ifdef __LITTLE_ENDIAN__
265 			data >>= 24;
266 #endif
267 			rc = __put_user((u8)data, (u8 __user *)ubuf);
268 			break;
269 		}
270 		if (rc)
271 			return -EFAULT;
272 		*ppos += len;
273 		ubuf += len;
274 		todo -= len;
275 	}
276 
277 	return count;
278 }
279 
280 static ssize_t lpc_debug_write(struct file *filp, const char __user *ubuf,
281 			       size_t count, loff_t *ppos)
282 {
283 	struct lpc_debugfs_entry *lpc = filp->private_data;
284 	u32 data, pos, len, todo;
285 	int rc;
286 
287 	if (!access_ok(VERIFY_READ, ubuf, count))
288 		return -EFAULT;
289 
290 	todo = count;
291 	while (todo) {
292 		pos = *ppos;
293 
294 		/*
295 		 * Select access size based on count and alignment and
296 		 * access type. IO and MEM only support byte acceses,
297 		 * FW supports all 3.
298 		 */
299 		len = 1;
300 		if (lpc->lpc_type == OPAL_LPC_FW) {
301 			if (todo > 3 && (pos & 3) == 0)
302 				len = 4;
303 			else if (todo > 1 && (pos & 1) == 0)
304 				len = 2;
305 		}
306 
307 		/*
308 		 * Similarly to the read case, we have some trickery here but
309 		 * it's different to handle. We need to pass the value to OPAL in
310 		 * a register whose layout depends on the access size. We want
311 		 * to reproduce the memory layout of the user, however we aren't
312 		 * doing a load from user and a store to another memory location
313 		 * which would achieve that. Here we pass the value to OPAL via
314 		 * a register which is expected to contain the "BE" interpretation
315 		 * of the byte sequence. IE: for a 32-bit access, byte 0 should be
316 		 * in the MSB. So here we *do* need to byteswap on LE.
317 		 *
318 		 *           User bytes:    LE "data"  OPAL "data"
319 		 *  32-bit:  B0 B1 B2 B3    B3B2B1B0   B0B1B2B3
320 		 *  16-bit:  B0 B1          0000B1B0   0000B0B1
321 		 *   8-bit:  B0             000000B0   000000B0
322 		 */
323 		switch(len) {
324 		case 4:
325 			rc = __get_user(data, (u32 __user *)ubuf);
326 			data = cpu_to_be32(data);
327 			break;
328 		case 2:
329 			rc = __get_user(data, (u16 __user *)ubuf);
330 			data = cpu_to_be16(data);
331 			break;
332 		default:
333 			rc = __get_user(data, (u8 __user *)ubuf);
334 			break;
335 		}
336 		if (rc)
337 			return -EFAULT;
338 
339 		rc = opal_lpc_write(opal_lpc_chip_id, lpc->lpc_type, pos,
340 				    data, len);
341 		if (rc)
342 			return -ENXIO;
343 		*ppos += len;
344 		ubuf += len;
345 		todo -= len;
346 	}
347 
348 	return count;
349 }
350 
351 static const struct file_operations lpc_fops = {
352 	.read =		lpc_debug_read,
353 	.write =	lpc_debug_write,
354 	.open =		simple_open,
355 	.llseek =	default_llseek,
356 };
357 
358 static int opal_lpc_debugfs_create_type(struct dentry *folder,
359 					const char *fname,
360 					enum OpalLPCAddressType type)
361 {
362 	struct lpc_debugfs_entry *entry;
363 	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
364 	if (!entry)
365 		return -ENOMEM;
366 	entry->lpc_type = type;
367 	debugfs_create_file(fname, 0600, folder, entry, &lpc_fops);
368 	return 0;
369 }
370 
371 static int opal_lpc_init_debugfs(void)
372 {
373 	struct dentry *root;
374 	int rc = 0;
375 
376 	if (opal_lpc_chip_id < 0)
377 		return -ENODEV;
378 
379 	root = debugfs_create_dir("lpc", powerpc_debugfs_root);
380 
381 	rc |= opal_lpc_debugfs_create_type(root, "io", OPAL_LPC_IO);
382 	rc |= opal_lpc_debugfs_create_type(root, "mem", OPAL_LPC_MEM);
383 	rc |= opal_lpc_debugfs_create_type(root, "fw", OPAL_LPC_FW);
384 	return rc;
385 }
386 machine_device_initcall(powernv, opal_lpc_init_debugfs);
387 #endif  /* CONFIG_DEBUG_FS */
388 
389 void opal_lpc_init(void)
390 {
391 	struct device_node *np;
392 
393 	/*
394 	 * Look for a Power8 LPC bus tagged as "primary",
395 	 * we currently support only one though the OPAL APIs
396 	 * support any number.
397 	 */
398 	for_each_compatible_node(np, NULL, "ibm,power8-lpc") {
399 		if (!of_device_is_available(np))
400 			continue;
401 		if (!of_get_property(np, "primary", NULL))
402 			continue;
403 		opal_lpc_chip_id = of_get_ibm_chip_id(np);
404 		break;
405 	}
406 	if (opal_lpc_chip_id < 0)
407 		return;
408 
409 	/* Setup special IO ops */
410 	ppc_pci_io = opal_lpc_io;
411 	isa_io_special = true;
412 
413 	pr_info("OPAL: Power8 LPC bus found, chip ID %d\n", opal_lpc_chip_id);
414 }
415