xref: /linux/arch/powerpc/platforms/powernv/opal-lpc.c (revision 58d416351e6df1a41d415958ccdd8eb9c2173fed)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * PowerNV LPC bus handling.
4  *
5  * Copyright 2013 IBM Corp.
6  */
7 
8 #include <linux/kernel.h>
9 #include <linux/of.h>
10 #include <linux/bug.h>
11 #include <linux/io.h>
12 #include <linux/slab.h>
13 #include <linux/debugfs.h>
14 
15 #include <asm/machdep.h>
16 #include <asm/firmware.h>
17 #include <asm/opal.h>
18 #include <asm/prom.h>
19 #include <linux/uaccess.h>
20 #include <asm/isa-bridge.h>
21 
22 static int opal_lpc_chip_id = -1;
23 
24 static u8 opal_lpc_inb(unsigned long port)
25 {
26 	int64_t rc;
27 	__be32 data;
28 
29 	if (opal_lpc_chip_id < 0 || port > 0xffff)
30 		return 0xff;
31 	rc = opal_lpc_read(opal_lpc_chip_id, OPAL_LPC_IO, port, &data, 1);
32 	return rc ? 0xff : be32_to_cpu(data);
33 }
34 
35 static __le16 __opal_lpc_inw(unsigned long port)
36 {
37 	int64_t rc;
38 	__be32 data;
39 
40 	if (opal_lpc_chip_id < 0 || port > 0xfffe)
41 		return 0xffff;
42 	if (port & 1)
43 		return (__le16)opal_lpc_inb(port) << 8 | opal_lpc_inb(port + 1);
44 	rc = opal_lpc_read(opal_lpc_chip_id, OPAL_LPC_IO, port, &data, 2);
45 	return rc ? 0xffff : be32_to_cpu(data);
46 }
47 static u16 opal_lpc_inw(unsigned long port)
48 {
49 	return le16_to_cpu(__opal_lpc_inw(port));
50 }
51 
52 static __le32 __opal_lpc_inl(unsigned long port)
53 {
54 	int64_t rc;
55 	__be32 data;
56 
57 	if (opal_lpc_chip_id < 0 || port > 0xfffc)
58 		return 0xffffffff;
59 	if (port & 3)
60 		return (__le32)opal_lpc_inb(port    ) << 24 |
61 		       (__le32)opal_lpc_inb(port + 1) << 16 |
62 		       (__le32)opal_lpc_inb(port + 2) <<  8 |
63 			       opal_lpc_inb(port + 3);
64 	rc = opal_lpc_read(opal_lpc_chip_id, OPAL_LPC_IO, port, &data, 4);
65 	return rc ? 0xffffffff : be32_to_cpu(data);
66 }
67 
68 static u32 opal_lpc_inl(unsigned long port)
69 {
70 	return le32_to_cpu(__opal_lpc_inl(port));
71 }
72 
73 static void opal_lpc_outb(u8 val, unsigned long port)
74 {
75 	if (opal_lpc_chip_id < 0 || port > 0xffff)
76 		return;
77 	opal_lpc_write(opal_lpc_chip_id, OPAL_LPC_IO, port, val, 1);
78 }
79 
80 static void __opal_lpc_outw(__le16 val, unsigned long port)
81 {
82 	if (opal_lpc_chip_id < 0 || port > 0xfffe)
83 		return;
84 	if (port & 1) {
85 		opal_lpc_outb(val >> 8, port);
86 		opal_lpc_outb(val     , port + 1);
87 		return;
88 	}
89 	opal_lpc_write(opal_lpc_chip_id, OPAL_LPC_IO, port, val, 2);
90 }
91 
92 static void opal_lpc_outw(u16 val, unsigned long port)
93 {
94 	__opal_lpc_outw(cpu_to_le16(val), port);
95 }
96 
97 static void __opal_lpc_outl(__le32 val, unsigned long port)
98 {
99 	if (opal_lpc_chip_id < 0 || port > 0xfffc)
100 		return;
101 	if (port & 3) {
102 		opal_lpc_outb(val >> 24, port);
103 		opal_lpc_outb(val >> 16, port + 1);
104 		opal_lpc_outb(val >>  8, port + 2);
105 		opal_lpc_outb(val      , port + 3);
106 		return;
107 	}
108 	opal_lpc_write(opal_lpc_chip_id, OPAL_LPC_IO, port, val, 4);
109 }
110 
111 static void opal_lpc_outl(u32 val, unsigned long port)
112 {
113 	__opal_lpc_outl(cpu_to_le32(val), port);
114 }
115 
116 static void opal_lpc_insb(unsigned long p, void *b, unsigned long c)
117 {
118 	u8 *ptr = b;
119 
120 	while(c--)
121 		*(ptr++) = opal_lpc_inb(p);
122 }
123 
124 static void opal_lpc_insw(unsigned long p, void *b, unsigned long c)
125 {
126 	__le16 *ptr = b;
127 
128 	while(c--)
129 		*(ptr++) = __opal_lpc_inw(p);
130 }
131 
132 static void opal_lpc_insl(unsigned long p, void *b, unsigned long c)
133 {
134 	__le32 *ptr = b;
135 
136 	while(c--)
137 		*(ptr++) = __opal_lpc_inl(p);
138 }
139 
140 static void opal_lpc_outsb(unsigned long p, const void *b, unsigned long c)
141 {
142 	const u8 *ptr = b;
143 
144 	while(c--)
145 		opal_lpc_outb(*(ptr++), p);
146 }
147 
148 static void opal_lpc_outsw(unsigned long p, const void *b, unsigned long c)
149 {
150 	const __le16 *ptr = b;
151 
152 	while(c--)
153 		__opal_lpc_outw(*(ptr++), p);
154 }
155 
156 static void opal_lpc_outsl(unsigned long p, const void *b, unsigned long c)
157 {
158 	const __le32 *ptr = b;
159 
160 	while(c--)
161 		__opal_lpc_outl(*(ptr++), p);
162 }
163 
164 static const struct ppc_pci_io opal_lpc_io = {
165 	.inb	= opal_lpc_inb,
166 	.inw	= opal_lpc_inw,
167 	.inl	= opal_lpc_inl,
168 	.outb	= opal_lpc_outb,
169 	.outw	= opal_lpc_outw,
170 	.outl	= opal_lpc_outl,
171 	.insb	= opal_lpc_insb,
172 	.insw	= opal_lpc_insw,
173 	.insl	= opal_lpc_insl,
174 	.outsb	= opal_lpc_outsb,
175 	.outsw	= opal_lpc_outsw,
176 	.outsl	= opal_lpc_outsl,
177 };
178 
179 #ifdef CONFIG_DEBUG_FS
180 struct lpc_debugfs_entry {
181 	enum OpalLPCAddressType lpc_type;
182 };
183 
184 static ssize_t lpc_debug_read(struct file *filp, char __user *ubuf,
185 			      size_t count, loff_t *ppos)
186 {
187 	struct lpc_debugfs_entry *lpc = filp->private_data;
188 	u32 data, pos, len, todo;
189 	int rc;
190 
191 	if (!access_ok(ubuf, count))
192 		return -EFAULT;
193 
194 	todo = count;
195 	while (todo) {
196 		pos = *ppos;
197 
198 		/*
199 		 * Select access size based on count and alignment and
200 		 * access type. IO and MEM only support byte acceses,
201 		 * FW supports all 3.
202 		 */
203 		len = 1;
204 		if (lpc->lpc_type == OPAL_LPC_FW) {
205 			if (todo > 3 && (pos & 3) == 0)
206 				len = 4;
207 			else if (todo > 1 && (pos & 1) == 0)
208 				len = 2;
209 		}
210 		rc = opal_lpc_read(opal_lpc_chip_id, lpc->lpc_type, pos,
211 				   &data, len);
212 		if (rc)
213 			return -ENXIO;
214 
215 		/*
216 		 * Now there is some trickery with the data returned by OPAL
217 		 * as it's the desired data right justified in a 32-bit BE
218 		 * word.
219 		 *
220 		 * This is a very bad interface and I'm to blame for it :-(
221 		 *
222 		 * So we can't just apply a 32-bit swap to what comes from OPAL,
223 		 * because user space expects the *bytes* to be in their proper
224 		 * respective positions (ie, LPC position).
225 		 *
226 		 * So what we really want to do here is to shift data right
227 		 * appropriately on a LE kernel.
228 		 *
229 		 * IE. If the LPC transaction has bytes B0, B1, B2 and B3 in that
230 		 * order, we have in memory written to by OPAL at the "data"
231 		 * pointer:
232 		 *
233 		 *               Bytes:      OPAL "data"   LE "data"
234 		 *   32-bit:   B0 B1 B2 B3   B0B1B2B3      B3B2B1B0
235 		 *   16-bit:   B0 B1         0000B0B1      B1B00000
236 		 *    8-bit:   B0            000000B0      B0000000
237 		 *
238 		 * So a BE kernel will have the leftmost of the above in the MSB
239 		 * and rightmost in the LSB and can just then "cast" the u32 "data"
240 		 * down to the appropriate quantity and write it.
241 		 *
242 		 * However, an LE kernel can't. It doesn't need to swap because a
243 		 * load from data followed by a store to user are going to preserve
244 		 * the byte ordering which is the wire byte order which is what the
245 		 * user wants, but in order to "crop" to the right size, we need to
246 		 * shift right first.
247 		 */
248 		switch(len) {
249 		case 4:
250 			rc = __put_user((u32)data, (u32 __user *)ubuf);
251 			break;
252 		case 2:
253 #ifdef __LITTLE_ENDIAN__
254 			data >>= 16;
255 #endif
256 			rc = __put_user((u16)data, (u16 __user *)ubuf);
257 			break;
258 		default:
259 #ifdef __LITTLE_ENDIAN__
260 			data >>= 24;
261 #endif
262 			rc = __put_user((u8)data, (u8 __user *)ubuf);
263 			break;
264 		}
265 		if (rc)
266 			return -EFAULT;
267 		*ppos += len;
268 		ubuf += len;
269 		todo -= len;
270 	}
271 
272 	return count;
273 }
274 
275 static ssize_t lpc_debug_write(struct file *filp, const char __user *ubuf,
276 			       size_t count, loff_t *ppos)
277 {
278 	struct lpc_debugfs_entry *lpc = filp->private_data;
279 	u32 data, pos, len, todo;
280 	int rc;
281 
282 	if (!access_ok(ubuf, count))
283 		return -EFAULT;
284 
285 	todo = count;
286 	while (todo) {
287 		pos = *ppos;
288 
289 		/*
290 		 * Select access size based on count and alignment and
291 		 * access type. IO and MEM only support byte acceses,
292 		 * FW supports all 3.
293 		 */
294 		len = 1;
295 		if (lpc->lpc_type == OPAL_LPC_FW) {
296 			if (todo > 3 && (pos & 3) == 0)
297 				len = 4;
298 			else if (todo > 1 && (pos & 1) == 0)
299 				len = 2;
300 		}
301 
302 		/*
303 		 * Similarly to the read case, we have some trickery here but
304 		 * it's different to handle. We need to pass the value to OPAL in
305 		 * a register whose layout depends on the access size. We want
306 		 * to reproduce the memory layout of the user, however we aren't
307 		 * doing a load from user and a store to another memory location
308 		 * which would achieve that. Here we pass the value to OPAL via
309 		 * a register which is expected to contain the "BE" interpretation
310 		 * of the byte sequence. IE: for a 32-bit access, byte 0 should be
311 		 * in the MSB. So here we *do* need to byteswap on LE.
312 		 *
313 		 *           User bytes:    LE "data"  OPAL "data"
314 		 *  32-bit:  B0 B1 B2 B3    B3B2B1B0   B0B1B2B3
315 		 *  16-bit:  B0 B1          0000B1B0   0000B0B1
316 		 *   8-bit:  B0             000000B0   000000B0
317 		 */
318 		switch(len) {
319 		case 4:
320 			rc = __get_user(data, (u32 __user *)ubuf);
321 			data = cpu_to_be32(data);
322 			break;
323 		case 2:
324 			rc = __get_user(data, (u16 __user *)ubuf);
325 			data = cpu_to_be16(data);
326 			break;
327 		default:
328 			rc = __get_user(data, (u8 __user *)ubuf);
329 			break;
330 		}
331 		if (rc)
332 			return -EFAULT;
333 
334 		rc = opal_lpc_write(opal_lpc_chip_id, lpc->lpc_type, pos,
335 				    data, len);
336 		if (rc)
337 			return -ENXIO;
338 		*ppos += len;
339 		ubuf += len;
340 		todo -= len;
341 	}
342 
343 	return count;
344 }
345 
346 static const struct file_operations lpc_fops = {
347 	.read =		lpc_debug_read,
348 	.write =	lpc_debug_write,
349 	.open =		simple_open,
350 	.llseek =	default_llseek,
351 };
352 
353 static int opal_lpc_debugfs_create_type(struct dentry *folder,
354 					const char *fname,
355 					enum OpalLPCAddressType type)
356 {
357 	struct lpc_debugfs_entry *entry;
358 	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
359 	if (!entry)
360 		return -ENOMEM;
361 	entry->lpc_type = type;
362 	debugfs_create_file(fname, 0600, folder, entry, &lpc_fops);
363 	return 0;
364 }
365 
366 static int opal_lpc_init_debugfs(void)
367 {
368 	struct dentry *root;
369 	int rc = 0;
370 
371 	if (opal_lpc_chip_id < 0)
372 		return -ENODEV;
373 
374 	root = debugfs_create_dir("lpc", arch_debugfs_dir);
375 
376 	rc |= opal_lpc_debugfs_create_type(root, "io", OPAL_LPC_IO);
377 	rc |= opal_lpc_debugfs_create_type(root, "mem", OPAL_LPC_MEM);
378 	rc |= opal_lpc_debugfs_create_type(root, "fw", OPAL_LPC_FW);
379 	return rc;
380 }
381 machine_device_initcall(powernv, opal_lpc_init_debugfs);
382 #endif  /* CONFIG_DEBUG_FS */
383 
384 void __init opal_lpc_init(void)
385 {
386 	struct device_node *np;
387 
388 	/*
389 	 * Look for a Power8 LPC bus tagged as "primary",
390 	 * we currently support only one though the OPAL APIs
391 	 * support any number.
392 	 */
393 	for_each_compatible_node(np, NULL, "ibm,power8-lpc") {
394 		if (!of_device_is_available(np))
395 			continue;
396 		if (!of_get_property(np, "primary", NULL))
397 			continue;
398 		opal_lpc_chip_id = of_get_ibm_chip_id(np);
399 		of_node_put(np);
400 		break;
401 	}
402 	if (opal_lpc_chip_id < 0)
403 		return;
404 
405 	/* Does it support direct mapping ? */
406 	if (of_get_property(np, "ranges", NULL)) {
407 		pr_info("OPAL: Found memory mapped LPC bus on chip %d\n",
408 			opal_lpc_chip_id);
409 		isa_bridge_init_non_pci(np);
410 	} else {
411 		pr_info("OPAL: Found non-mapped LPC bus on chip %d\n",
412 			opal_lpc_chip_id);
413 
414 		/* Setup special IO ops */
415 		ppc_pci_io = opal_lpc_io;
416 		isa_io_special = true;
417 	}
418 }
419